World Cement September Issue 2021 by PalladianPublications

September 2021

HOW

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CONTENTS 03 Comment 05 News

GEARS, DRIVES & MOTORS 48 The Benefits Of A Better Brush

REGIONAL REPORT: CENTRAL ASIA 10 Cement In Central Asia

Mathis Menzel, Menzel Elektromotoren, explains why cement producers should forgo brush-lifting devices for slip ring motors in favour of sourcing high-quality, application-specific brushes.

Prashant Singh, CW Group, reviews the state of the cement and construction sectors in Central Asia.

CRUSHING & GRINDING 15 Focusing On The Factors For Success Dr. Caroline Woywadt, Gebr. Pfeiffer, discusses the various factors that can impact the performance of VRMs and explains how operators can achieve optimum efficiency from their equipment.

21 California Crushing Sathish Krishnamoorthy, FLSmidth, outlines how a new heavy-duty roller breaker helped to eliminate clinker crusher blockages at CalPortland’s Oro Grande plant.

KILNS & BURNERS 28 Taking Advantage Of AI Liran Akavia, Seebo, explains how AI can help cement manufacturers to reduce emissions, whilst maintaining or even improving their production process efficiency and key business KPIs.

GREEN CEMENT 55 Greener Times Call For Greener Measures Hans Conrads, PROMECON, suggests how measurement technologies can be optimised in order to achieve more ‘green’ cement production.

59 India: Striving For Sustainability Dr. S. B. Hegde describes the major strides the Indian cement industry has recently taken towards achieving sustainability and a circular economy.

63 Strong And Sustainable Riccardo Stoppa, GCP Applied Technologies, outlines the sustainable cement additive solutions that could help to protect the strength and performance of cement whilst curbing CO2 emissions.

67 Opting For Optimisation

33 The Natural Choice

Marco Rovetta, CTP Team, considers how cement producers could work towards achieving carbon neutrality, starting with the optimisation of existing plant equipment.

Unitherm outlines the benefits for cement producers converting to complete or partial natural gas firing.

71 Wise About Waste

REFRACTORIES 37 Getting The Most Out Of Maintenance

Jori Kaaresmaa, BMH Technology Oy, outlines the implementation of a waste-to-RDF production plant in Umm Al Quwain, United Arab Emirates.

Lars Lindgren, Brokk Inc., and Heather Harding, Bricking Solutions, discuss how working with specialised equipment from innovative manufacturers can greatly increase productivity, safety and the overall quality of refractory maintenance.

FANS & BLOWERS 75 Modern Maintenance And Monitoring

43 Ready For Rapid Recovery & Repair

The New York Blower Company details an innovative strategy for equipment management and maintenance that leverages robust fan design in combination with advanced remote monitoring systems and IIoT technologies.

Herbert Hoenl, REFKO, explains how successful and long-lasting emergency rotary kiln repairs can be achieved, resulting in safer operation of the kiln until a planned shutdown can take place.

ON THE COVER Industrial drones have incredible range and flexibility. With thyssenkrupp’s drone inspection solution, cement plant operators can inspect large areas in a very short period of time and even reach high and obstructed places without expensive scaffolding or risky industrial climbing – from thermal inspection for coke ovens, visual inspection for chimneys and silos, as well as volume measurement and mass calculation for stockpiles. The flight history is documented and can subsequently be evaluated by thyssenkrupp’s industry experts.

September 2021

HOW

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SUBSCRIPTIONS Annual subscription (published monthly): £160 UK including postage/£175 (e245) overseas (postage airmail)/US$280 USA/Canada (postage airmail). Two year subscription (published monthly): £256 UK including postage/£280 (e392) overseas (postage airmail)/US$448 USA/Canada (postage airmail). Claims for non receipt of issues must be made within 4 months of publication of the issue or they will not be honoured without charge. Applicable only to USA and Canada: WORLD CEMENT (ISSN No: 0263-6050, USPS No: 020-996) is published monthly by Palladian Publications, GBR and is distributed in the USA by Asendia USA, 17B S Middlesex Ave, Monroe NJ 08831. Periodicals postage paid New Brunswick, NJ and additional mailing offices. POSTMASTER: send address changes to World Cement, 701C Ashland Ave, Folcroft PA 19032 Copyright © Palladian Publications Ltd 2021. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owner. All views expressed in this journal are those of the respective contributors and are not necessarily the opinions of the publisher, neither do the publishers endorse any of the claims made in the articles or the advertisements. Uncaptioned images courtesy of Adobe Stock. Printed in the UK. Palladian Publications Ltd 15 South Street, Farnham, Surrey GU9 7QU, UK Tel +44 (0)1252 718999 Fax +44 (0)1252 718992 Email: mail@worldcement.com Website: www.worldcement.com

September 2021 World Cement

he Mineral Products Association (MPA), the UK trade association for the cement and concrete industry, has produced a roadmap for these sectors to become, not just carbon neutral, but carbon negative by 2050. Cement and concrete producers in the UK already have an impressive decarbonisation record, leading many other sectors by having already cut emissions 53% since 1990, but there’s still more to be done. In 2018, CO2 emissions for UK cement and concrete production amounted to 7.3 million t – the MPA’s roadmap seeks to remove this remaining carbon footprint without falling into the trap of ‘carbon leakage’, i.e. offshoring emissions to countries with more lax environmental policies. The roadmap outlines the key technology levers that will allow cement and concrete production to become carbon negative. In brief, they are as follows: f Indirect emissions from decarbonised electricity – CO2 reduction: 27.05 kgCO2/t or 4% – Decarbonising the electricity grid will encourage electrification and promote the use of technologies such as plasma energy & CCUS, and other advanced manufacturing techniques. f Transport – CO2 reduction: 44.45 kgCO2/t or 7% – New transport fleets, moving away from fossil fuels, and increased use of rail freight. f Low carbon cements and concretes – CO2 reduction: 76.28 kgCO2/t or 12% – Continued development and adoption of low-carbon cements and revised building standards. f Fuel switching – CO2 reduction: 99.45 kgCO2/t or 16% – Availability of biomass is sufficient to provide 70% of the heat required for cement production. Investment in hydrogen production and delivery networks will support further CO2 savings. f CCUS – CO2 reduction: 390.97 kgCO2/t or 61% – The MPA states: “This transformative technology represents the most significant and technically disruptive investment in the roadmap.” f Carbonation – CO2 reduction: 12% – By 2050, techniques to optimise carbonation will be used to significantly increase its impact. f Thermal mass – CO2 reduction: 44% – The cumulative deployment of concrete’s thermal mass equates to an estimated 14% saving of 2050 UK electricity consumption from avoided heating and cooling. This equates to 44% of 2018 concrete and cement emissions levels. Collaboration between government and industry will be key in reaching net zero and beyond. In the MPA’s own words, there needs to be “a shared understanding and pathway to net zero, one where policy, financial and infrastructure enablers are coordinated to support the sector’s decarbonisation and to manage a just transition.” There’s a lot of work to be done, but progress is already being made on many of these levers. As always, World Cement will be here to provide you with the latest developments as they happen.

Note For more information on the MPA’s ‘Roadmap to Beyond Net Zero’, visit: https://bit.ly/3DwNe4f 3

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NEWS CalPortland joins the Wildlife Habitat Council CalPortland has joined the Wildlife Habitat Council (WHC) as a corporate member, formalising the company’s commitment to integrating biodiversity and conservation action into its sustainability efforts. Through WHC membership, CalPortland seeks to involve employees and community stakeholders in sustainability activities and earn recognition via WHC Conservation Certification®, the only global, third-party verified biodiversity standard. “CalPortland has already made great strides in sustainability through its commitment to sustainable cement and concrete production practices and energy efficiency,” said Margaret O’Gorman, President, Wildlife Habitat Council. “We commend the company’s commitment to biodiversity action and look forward to working with CalPortland as the company mobilises corporate lands for strategic conservation efforts.” Among CalPortland’s goals is to focus on science-based conservation activities designed to enhance land management tactics, provide life cycle needs for native wildlife, and improve the environment and communities in which they operate. “Our membership with the Wildlife Habitat Council reflects CalPortland’s ongoing commitment to the environment. It provides a unique opportunity to take corporate sustainability goals and objectives and translate them into tangible, on-the-ground actions, which ensures a sustainable environment for the next generation,” said Allen Hamblen, CalPortland President/CEO. WHC has been working at the intersection of business and conservation for over 30 years, advising global companies to provide biodiversity uplift on company lands. WHC members represent a wide range of industries and locations and include companies such as Bayer, IBM, Niagara Water, and Toyota Motor North America.

TERI & GCCA India to work on sustainability in cement sector The Energy and Resources Institute (TERI) and the Global Cement and Concrete Association September 2021 World Cement

(GCCA) India has announced the signing of a Memorandum of Understanding (MoU) under which the two aim to facilitate and accelerate sustainable development of the cement and concrete sectors, including their value chain partners across India. GCCA India focuses on advancing sustainable construction while demonstrating industrial sustainable leadership in Indian cement and concrete manufacturing. The organisation leads the industry’s drive to carbon neutrality by 2050 in line with global climate targets, as well as the Low Carbon Technology Roadmap. Under the MoU, TERI will provide its domain expertise and knowledge to support GCCA India’s work to achieve sustainability in the Indian cement and concrete sector. The collaboration will see TERI’s involvement in GCCA India work programmes while GCCA India and its members will support TERI’s projects on technology innovation, energy efficiency enhancement, and resource efficiency implementation. “The demand for cement and concrete will only increase in the decades to come due to population growth and urbanisation. Therefore, reducing CO2 emissions in the cement and concrete industry is critically important,” said Mr. Mahendra Singhi, Chair, GCCA India. “Working with stakeholders across sectors and with civil society will be essential to achieving our sustainability goals – our MoU with TERI will bring world-class expertise, resources, and research that will be invaluable to our industry’s drive to carbon neutrality,” he added. “The Indian cement and concrete industry has made significant reductions to its carbon emissions in recent years. We are excited to work with GCCA India and its membership to accelerate the decarbonisation of the sector and improving sustainable development,” said Dr. Vibha Dhawan, Director General, TERI.

CEMEX recognised for waste to energy co-processing of residual waste CEMEX Philippines’ solid cement plant in San Jose, Antipolo, was recently recognised by the Department of Environment and Natural Resources’ (DENR’s) Environmental 5

NEWS DIARY CEMENTTECH 2021 10 – 12 October, 2021 Jiangxi, China Joannalong@ccpitbm.org www.cementtech.org

BULKEX21 12 – 13 October, 2021 Chesford Grange, Warwickshire, UK secretary@mhea.co.uk www.mhea.co.uk

CEMBUREAU: Cementing Europe’s Future 12 October, 2021 Brussels, Belgium & Online j.meaden@cembureau.eu www.cembureau.eu/events/

09 – 10 November, 2021 worldcement.com/wct2021

SOLIDS & RECYCLINGTECHNIK Dortmund 16 – 17 February, 2022 Dortmund, Germany www.solids-dortmund.de

Management Bureau (EMB) for its small scale waste to energy co-processing of residual wastes. This is in keeping with the cement company’s commitment towards tackling climate change, with proper environmental management being one of the concrete steps taken. The recognition serves as another validation that CEMEX has, for many years, been true to its commitment towards sustainability and environmental management. This further fulfils CEMEX’s ‘Future in Action’ global strategy to address Climate Change which centres around reducing its CO2 emissions by 35% by 2025 and around 40% by 2030. At the core of CEMEX’s environmental management initiative is co-processing, which is a sustainable way of processing wastes, specifically single-use plastics, using a cement kiln. This industrial method helps in effectively reducing wastes being dumped on landfills and water bodies. It also helps in recycling the materials as additional energy sources (alternative fuel) during cement production. Solid Cement Plant Director, Santiago Ortiz, received the plaque of recognition from DENR-EMB CALABARZON Regional Director Noemi Paranada through a recent virtual awarding ceremony. “This recognition is a testament to our commitment that we must continuously push for the reduction of our CO2 emissions and protect our environment,” Ortiz said. CEMEX’s steadfast campaigns towards climate change earned them different awards from DENR. This includes DENR-EMB’s recognition of the Solid Cement plant in 2017 for its commitment to the government’s Adopt-a-River programme. The company also received Best Environmental Technology and Best Available Practice for exemplifying best practices in implementing the Ecological Solid Waste Management Act of 2000 under Republic Act (RA) 9003. In 2019, the DENR-EMB conferred an award for its innovative waste management solutions such as co-processing and for TSeK (Tamang Segregasyon Para Sa Kalikasan) programme services.

Ambuja Cements Limited starts trial run at Marwar plant Ambuja Cements Limited has started the trial run at its state-of-the-art greenfield integrated plant (Marwar Cement Works) in the Nagaur district of Rajasthan. The Honourable Chief Minister of Rajasthan Shri Ashok Gehlot virtually inaugurated the trial runs at the new plant. Built over an investment of Rs. 23.5 billion, this Greenfield integrated plant enhances Ambuja’s clinker capacity by 3 MTPA and helps in improving cement sales by 5 MTPA, thereby contributing to a long term strategy of capacity expansion. The plant has a waste heat recovery system (WHRS) that converts waste heat derived during the production process into energy. Speaking on the occasion, Shri Ashok Gehlot, the Honourable Chief Minister of Rajasthan, said, “I am delighted to inaugurate World Cement September 2021

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NEWS the trial run at Marwar Cement Plant of Ambuja as we dedicate it to meet the infrastructure requirements of the nation. Cement is one of the most important materials for infrastructure, and the nation’s growth. I am happy that Ambuja Cement and Holcim Group have chosen Rajasthan for their expansion plan through this plant. I am happy to note that the state is ready to provide all assistance necessary for the progress of the industry. It will be our common endeavour that we can become a strong partner for Rajasthan and the country.” “It’s a proud moment for us at Ambuja Cements. Our endeavour shall always be to become a strong partner and ‘Builders of Progress’ for India. I take this opportunity to thank the Honourable Chief Minister, all the state officials and our various stakeholders who have helped us in setting up Marwar Project,” said Mr. Neeraj Akhoury, MD and CEO, Ambuja Cements Ltd. Marwar Cement Works is the third plant of Holcim Group in the Rajasthan, after Rabariwas and Lakheri. It is also the second integrated plant of Ambuja in Rajasthan, and sixth in the country.

Holcim’s Beckum cement plant awarded platinum CSC sustainability certificate The Beckum cement plant has received the CSC sustainability certificate in platinum. The award provides information about how ecologically, socially and economically responsible a plant is. Almost 50 locations of the Holcim Deutschland Group in Germany and the Netherlands can already display CSC certificates. Every company that uses the cement of a CSC-certified location also improves its own rating – because the gold level for concrete manufacturers can only be achieved with the use of certified cement. Project Manager, Eberhard Liebig, said, “With the platinum award, we have reached the highest possible level and are thus providing our cement customers with the best possible support in their own sustainability certification.” With the CSC certification of its cement plants, Holcim lays the foundation for the construction of sustainable buildings and gives downstream users, planners and clients the necessary security in their actions. Certification takes place in 8

categories such as management, environment, social, economic and product chain. The CSC certification system is recognised by the DGNB (German Sustainable Building Council), BREEAM (Building Research Establishment Environmental Assessment Method) and LEED (Leadership in Energy and Environmental Design) Leadership. Sustainability has many components. In addition to avoiding CO2, the conservation of natural resources is increasingly becoming the focus of corporate responsibility. As a founding member of the Concrete Sustainability Council (CSC), Holcim has been striving for years to promote sustainable business practices.

IAC to install roller press system at Lehigh Port Canaveral Industrial Accessories Company (IAC) has been named the EPC contractor responsible for the design, supply, and installation of a new roller press system at the Lehigh Cement grinding facility in Port Canaveral, Florida. The project has a targeted completion date of Q4 2022. To meet customer requirements, IAC will supply a Hydraulic Roller Press (HRP) manufactured by FLSmidth, which will enable the plant to further optimise its grinding operations and increase efficiency. In addition to the HRP equipment, IAC will provide engineering services, project management, electrical and instrumentation equipment, hoppers, bins, belt conveyors, bucket elevators, dust collectors, piping, foundations, structural steel supply and erection, and mechanical and electrical construction. Construction and foundations will be self-performed by Adelphi Construction LLC, a wholly owned subsidiary of IAC. “Industrial customers understand that proper design and on-time construction of the system is just as important as the equipment itself,” said Glenn Smith, IAC Founder and Chief Executive Officer. “We are delighted to be chosen by Lehigh Cement as the EPC contractor of this important project. We’re also pleased to collaborate with FLSmidth to ensure the customer has the right equipment solution that is engineered and commissioned according to their project timeline.” World Cement September 2021

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CENTRAL ASIA Prashant Singh, CW Group, reviews the state of the cement and construction sectors in Central Asia.

hen 2021 rolled around, there was renewed optimism across the world on the back of expectations for a rebound year after a largely disastrous 2020 both in terms of the global economic impact and the loss of life from the pandemic.

Central Asian Overview Central Asia has been experiencing stable growth since 2019, including last year despite the pandemic. According to CW’s Global Volume Forecast Report May 2021, Eastern Europe and the CIS region’s cement demand is expected to grow at a rate of 4.2% in 2021. Growth expectations for Central Asia are moderately higher at an estimated 5 – 6%. The spread of the pandemic has made its presence felt in the region, adversely impacting economic growth and societal well-being. Still, Uzbekistan was only one of the three European and Central Asian economies that was able to maintain positive economic growth in 2020. The region’s cement demand is expected to remain robust especially in the major markets of Kazakhstan and Uzbekistan.

Uzbekistan Uzbekistan’s economy is export-driven with a strong reliance on gold, petroleum gas, and natural cotton yarn. In Uzbekistan, cement production in 2021 is expected to be around 16.4 million t according to the Uzstroymaterialy Association’s forecast. Effectively this would translate into an increase of almost 30% or 3.9 million t more than 2020. Demand, however, is expected to be between 17 to 18 million t driven by strong construction demand, primarily housing construction. At the beginning of 2021, a total of 33 cement plants were operational, with the main concentration of production sites in Tashkent, Navoi, and Fergana. More than three-quarters of all cement produced in Uzbekistan comes from only six enterprises: JSC Kyzylkumcement, Akhangarantsement, Kuvasaycement, Bekabadcement, Jizzakh, and Sherabad cement plants (part of Almalyk Mining and Metallurgical Plant JSC).

With sustained cement demand growth expected to remain a permanent fixture for at least the next two decades given the requirement for 145 000 new housing units annually to keep up with population trends as well as the replacement of old housing stock, additional capacity is expected to come online. In 2021 alone, 10 new enterprises with a cumulative capacity of 5 million t are expected to be launched. Over the 2021 – 2023 timeline, an additional investment of US$500 million and a capacity of 3 million t is expected to be implemented in the autonomous Republic of Karakalpakstan located within Uzbekistan. The region has seen growing Chinese influence over recent years, especially in the construction sector, with an increasing number of companies making a play, as China focuses on expanding the Belt and Road Initiative (BRI), an important strategic project linking China through Russia to Europe, as discussed in depth in CW Group’s World Cement Report. It is expected that the coming years will see yet more Chinese players making investments in the Uzbek cement sector. Numerous infrastructure projects will help to sustain demand diversification and reduce dependence on housing construction. The Uzbekistan-Kyrgyzstan-China railway is an extremely important strategic project that is expected to be completed in the next few years, and will aid in improving the transport links between the three countries. This is especially important given that both Uzbekistan and Kyrgyzstan are land-locked. This route gains even more significance given a previously agreed plan (02 February 2021) to build a 573 km route from Mazar-e-Sharif to Peshawar, via Kabul, thus linking Pakistan, Uzbekistan, and Afghanistan. This was even hailed in Uzbekistan as ‘the event of the century’ because of its possible transformative impact on Uzbekistan’s economy. This project has an estimated cost of US$5 billion, will open Pakistani seaports on the Arabian Gulf to Uzbekistan, and is expected to aid in Afghanistan’s gradual integration into the Central Asian economic system. However, given the deteriorating security situation in Afghanistan, in addition to differences in railway gauges utilised in the three countries and the inhospitable terrain of the Hindu Kush mountains, where a significant portion of the construction will take place, it is expected that the railway link through China remains the most likely, if not the most economical project. This will ensure that Uzbekistan’s reliance on China only grows. There are numerous other railway projects including additional lines for the Tashkent and upgrading over various railway lines across the country. Additionally, some 29 road infrastructure projects are currently expected to be implemented and completed between 2020 – 2025. These projects were announced last

year and are currently being finalised, with work having commenced on some of them.

Kazakhstan Kazakhstan is the region’s largest economy by some way, with a strong reliance on exports of natural resources, namely crude oil and petroleum gas among others. In 2020, the country’s GDP was negatively impacted as the global economy experienced its worst year since the great depression with oil consumption drastically declining. With proactive measures from the government and the national banking regulator, various measures were adopted that helped mitigate and defray the impact of the economic challenges brought about by the pandemic. In April 2020, the Nurly Zhol State Infrastructure Development Programme for 2020 – 2025 was adopted by the government and aims to implement 112 infrastructure projects with a total value of 5.5 trillion tenge (approximately US$12.8 billion) between 2020 to 2025. In April 2021, the number of construction projects from 2021 to 2025 increased to 158, in addition to 23 specific transportation and 58 mining projects. The construction sector in Kazakhstan is, much like its neighbour Uzbekistan, driven by housing construction. In 2021, a total of 11 cement plants are operational (with a total production capacity of 16.5 million tpy), as opposed to 12 plants the previous year. Given the strong prospects for the Kazakh economy, as crude oil and natural gas prices rebound on the back of global economic recovery, there remain prospects for further developments in production capacity. As with most other countries in the region, China is expected to be a major player in the market as the country continues to increase its presence across the BRI region, especially as production capacity and rigorous environmental measures in China restrict domestic avenues for growth. In 2020, there were 15.3 million m2 of housing construction completed for 1.9 trillion tenge. The Ministry of Industry and Infrastructure Development stated that in 2021 the state expects 17 million m2 to be constructed. In total, during the period of 2021 – 25, an estimated 103 million m2 of new housing will be constructed. The period from January to April 2021 saw a 16% increase in the price of building materials. Kazakhstan’s construction sector has been negatively impacted by its reliance on imports, with 50% of all steel structures and over 99% of sheet glass being imported. While the country is, for the time being, self-reliant in terms of cement and concrete, pressure on these sectors is expected as demand continues to be robust. A growing cause of concern is the bottlenecks put in place by the state itself. Currently, only the

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Kazakhstan Housing Company provides a ‘warranty’ in cases where the construction company is unable to complete a project. Under the current regulations set by the National Bank, there is a limit to the guarantee that can be provided to a construction project. For example, if a major developer invests in a project, only one-fifth is covered by guarantees. With the increase in building material prices, and government mandates requiring specific volumes of public housing construction at previously agreed prices, there is rising fear amongst construction companies that a wave of defaults is next to certain unless the government issues a decree revising the prices of existing contracts that were in place from January 2019 to 2021.

Kyrgyzstan and Tajikistan Tajikistan has 19 cement plants with a total estimated production capacity of about 5.6 million tpy, with the commissioning of a 0.6 million tpy grinding plant in the Jaloliddini Balkhi district of Khatlon province by Mohir Cement. Chinese-Tajik joint ventures dominate the cement industry landscape in the country and will likely continue to determine the sector’s growth going forwards. Kyrgyzstan’s total cement capacity is 3 million tpy. Domestic consumption remains below 2 million tpy, while the remaining production is destined for

SEEING IS

BELIEVING

exports, predominantly to Uzbekistan. This scenario is likely to continue for the next few years while domestic demand catches up to existing production capacity. Further investment in the country’s cement sector is not expected in the short-to-medium term.

Summary CW’s outlook for the Central Asian region in terms of cement demand in 2021 is positive, but comes with some important caveats. It assumes that the recovery trajectory continues in the same vein into the second half of 2021 and that there is sufficient vaccine supply to provide the necessary confidence boost to consumption and consequentially, to employment, thus leading to a sustained global economic recovery and more importantly, a recovery in the demand for oil.

About the author Prashant Singh is the Associate Director at CW Group. Prashant is responsible for providing business insights for CW Research and aiding in advisory project implementations. He also holds Bachelor’s Degrees in International Business and Economics from Saint Peter’s University and a Master of Science degree in International Business from Seton Hall University, USA.

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FOCUSING ON THE FACTORS FOR

SUCCESS

Dr. Caroline Woywadt, Gebr. Pfeiffer, discusses the various factors that can impact the performance of VRMs and explains how operators can achieve optimum efficiency from their equipment. or decades, vertical roller mills have been in use in the cement industry for the grinding of cement raw material and coal. Since the 1980s, this mill type has also been used for combined or separate grinding of cement clinker and additives. During the last three decades, the number of installations for grinding cement and blast furnace slag has increased significantly. The MPS mill has been used for decades for the grinding of materials such as cement raw material, cement clinker, solid fuels, gypsum,

and limestone, etc. Due to the trend towards increasing capacities of individual grinding plants, the MVR mill was developed in the early 2000s and has been in industrial operation since 2006. This mill has since become well established for large units with an installed drive power of nearly 12 MW as well as compact systems known as ready2grind plants. More than 100 such mills are currently in operation or in order execution. Figure 1 shows the geographic distribution of plants with MVR mills.

Design feature comparison

Performance of the VRM

The design features of the MVR mill differ from the well-known MPS mill mainly in the areas of grinding element geometry, roller suspension and the number of rollers. The MVR roller mill is characterised by four or six grinding rollers and the use of flat grinding table liners. A roller module consists of the roller with cylindrical roller tyre, roller axle, roller arm, support pedestal and the hydraulic power input. In conjunction with the flat grinding table liner geometry, this type of roller suspension system achieves a parallel grinding gap between roller and table liner at any time. This has a positive effect on the vibration level of the mill and the energy input into the grinding bed. All machine parts that are relevant in terms of fluid dynamics, such as the hot gas channel, nozzle ring, SLS high-efficiency classifier and material feed, are of the same design as the parts that have been proven to be successful in the well-established MPS mills. The combination of three process steps in one system – drying, grinding, separating – makes the mill very versatile with regard to handling dry and moist feed materials, grinding to a very high fineness, and creating the product properties required by the different market areas.

The performance of a vertical roller mill is defined by a required throughput at a required fineness, paired with a low specific thermal and electric energy consumption. For cement grinding, the required product quality is the most important target, together with the aforementioned points. Some areas in general need special attention: Feed uniformity, metal detection and extraction, and preventive maintenance to name just a few. The levers to pull for a well performing vertical roller mill are operational parameters such as table speed, gas flow, working pressure and mechanical adjustments such as dam ring height and covering the nozzle ring. A smooth and stable mill operation with reduced or zero water spray is possible with a VRM, hence the ability to grind without external heat depends on the feed moisture of the material. When it comes to composite cements, the versatility of vertical roller mills is impressive. These mills are very flexible when it comes to the grinding of different materials, such as: Clinker, limestone, GBFS, pozzolana, fly ash, bottom ash, etc., with a wide range of properties. When moist materials are included in the feed mix, a heated rotary lock will be installed. When dry and already quite fine materials are used, an additional feeding point is provided at the classifier housing. When producing composite cements, the decision between the use of inter- or separate-grinding is often a point of discussion. The MVR mill is able to switch from inter-grinding to separate grinding depending on the client’s needs without any changes to the mill internals. Properties of, for example, GBFS and fly ash vary Figure 1. World map with MVR mills. widely. In line with the required product properties, it has to be taken into consideration that inter-grinding can result in finer fractions containing either very little or no GBFS or fly ash. Depending on the reactivity of GBFS, the mode of production can be achieved with inter-grinding as well with separate grinding of the single components. Operational experiences show that plants tend to grind clinker and GBFS together if GBFS is available with a good reactivity. One advantage of inter-grinding is the formation of a stable grinding bed due to clinker and GBFS granulometries which interact positively. If the GBFS needs to be Figure 2. Use of grinding aids (GA) at different product ground to a high fineness due to lower finenesses. 16

World Cement September 2021

HOW reactivity improves quality control.

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reactivity, separate grinding might be a better way to achieve the overall required properties of slag cements. MVR mills can be operated in both ways. For example, an MVR 6700 C-6 installed in Algeria produces limestone-composite cement by inter- and separate-grinding of limestone and CEM I. The limestone is pre-ground in the raw material mill MVR 6000 R-6. Feed material to the MVR 6700 C-6 is clinker and gypsum. The pre-ground limestone is injected into the classifier outlet and is homogenised with the CEM I in the filter and during transport to the product silos. Table 1 shows the performance results of inter- and separate-grinding.

success of the vertical roller mill. Originally, the goal was to achieve the same or similar particle size distribution (PSD). Today, however, it is clear that the PSD is not the only factor to impact the properties of the finished product. Product quality is impacted by feed material properties and the physical properties of the ground cement. The clinker and its chemistry, especially the C3A-content and its sourcing, suggesting potential moisture, mean that prehydration is a main factor for the product quality. The sulfate agent needs a balanced proportion of di-hydrate, hemi-hydrate and anhydrite. As a VRM has a significantly higher energy efficiency than a ball mill, much less Cement grinding heat is put into the grinding process. As a Over the past decades, the vertical roller mill result, the dehydration degree of the sulfate has replaced many ball mill grinding systems. agent is lower. The lower hemi-hydrate or The first MPS mill for cement was ordered in plaster content can be compensated for by 1979 and remains in operation today. With the the addition of more gypsum (within the limit development of the MVR mill, the duty series according to relevant standards), by the addition of a more reactive form of gypsum, has been changed for cement raw material and or by the addition of more heat to the system. cement grinding from type MPS to MVR mill. By installing the G4C ® system with a separate Nearly 70 MVR mills for cement grinding are currently in operation or under order execution. hammer mill and hot gas generator to partially Achieving the same quality of cement calcine the gypsum, the hemi-hydrate content produced in ball mills was essential for the can be controlled exactly for each clinker that is used. This is made possible by setting the outlet temperature of the hammer mill to adjust the proportion of hemi-hydrate. An additional factor impacting cement properties is the choice of supplementary cementitious materials (SCMs) or clinker replacement materials (CRMs). These materials influence grindability and operational behaviour, and reactivity.1 In many countries, limestone is the most easily available supplemental material. Limestone dilutes the clinker content of the cement and impacts strength development. If natural pozzolana is available, the hydraulic properties are advantageous for cement products.2 Figure 3. Fineness of different cement types ground in The performance of a vertical roller mill an MVR mill. can also be impacted by grinding aids (GA). Table 1. CEM II/A-L and CEM I produced in MVR 6700 C-6. Today, grinding aids are very common – not only Limestone cement OPC 2 OPC 1 for increasing production, Limestone injection (feeding but also for enhancing 18 % 0% 0% point at duct to filter) cement properties, Feed to mill (only Clinker and such as early strength 280 tph 240 tph 345 tph Gypsum) increase, workability, etc. MVR mills can be Total output 330 tph 240 tph 345 tph operated without grinding 4700 Blaine 4800 Blaine 3875 Blaine aids, but adding grinding Fineness aids can support their 4.0% R45 µm 3.0 % R32 µm 2.5% R45 µm performance. The general 17.6 kWh/t 24.5 kWh/t 18.7 kWh/t SPC mill coupling application of grinding 18

World Cement September 2021

aids depends strongly on the operating company and the region in which the plant is located. Other factors include the cement type and the fineness of the product. Figure 2 shows the use of grinding aids for different types of cement produced in MVR mills. In this evaluation, all operating MVR mills for cement and all different products ground are included (this is also true for the data in Figure 3). Cements with a fineness of less than 3500 cm2/g are generally ground without grinding aids, for fineness ranging between 3500 and 4500 cm2/g, one-third is ground with grinding aids, and for high fineness cement, more than two-thirds are ground with the application of grinding aids. Figure 3 shows the fineness for cementitious products ground in MVR mills. The types are divided into OPC, GBFS (blast furnace slag), PLC (limestone-cement), PSC (slag-cement), PPC (flyash-cement), and PPC-P (composite-cement with pozzolan). Cements with more than one SCM are classified according to the SCM with the highest proportion. Only OPC and PPC are ground to a fineness of less than 3500 cm 2/g; the major proportion of cements are ground in the range between 3500 and 4500 cm 2/g. More than one-third of the products of high fineness (> 4500 Blaine) are ground to 5000 cm2/g and higher. This reflects both the necessity of higher fineness for SCMs in order to achieve sufficient reactivity in the later application, and also the fact that OPC can be easily ground to a fineness of more than 5000 cm2/g in MVR mills. An important factor in the characterisation of cement properties is strength development in combination with setting times. National standards define the procedure for testing. Due to differences in those standards, the results of compressive strength development are not comparable to each other. Gebr. Pfeiffer has its own mortar laboratory and collects samples from operating MPS and MVR mills to characterise cement product properties. To ensure the reliability of results, the laboratory participates in annual round robin tests (ATIHL 3 and BE CERT4). The procedure for sample preparation, proportions for cement, sand and water are in accordance to EN 196-1. The properties of several cements produced in MPS and MVR mills are listed in Table 2. Nearly all OPC/CEM I products have developed a 28-day strength of 60 MPa or higher. High 28-day strength figures are

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achieved as well, with a product fineness of less than 4000 cm2/g. Early strength after two days is clearly impacted by clinker quality and, for composite cements, the type of composite is an additional factor. The composite cements achieve high 28-day strengths. Products need to be ground finely enough due to composites in order to achieve the required strength level. The given normal consistency figures have been determined in accordance with EN 196-3 and demonstrate that the workability of products from MVR mills meets the demands of industry. Custom specific adjustments have been made in many cases during the commissioning of MVR mills, for example: PSD adaptation, sulfate agent selection, or the use of the G4C® system to get precise plaster-content. These results show that cements ground in vertical roller mills are clearly on the same level compared to cements ground in ball mills.

Conclusion and outlook Many factors affect the performance of a vertical roller mill. The feed material is the basis for the product quality and has a fundamental impact on operational behaviour. With customised PSD adjustment and sulfate

agent matching, the required cement properties for all types of cement can be produced in MVR mills. With digitalisation and continuous technological improvement in MVR mills, continued progress towards client demands for sustainability and efficiency can be made.

References 1. WOYWADT, C., & HENRICH, B., ‘Indian cements produced in MVR- and MPS-mills – impact of composite material properties’, CI , Issue 4/2018, pp. 42 – 47. 2. WOYWADT, C., ‘Grinding with MVR’, World Cement, Nov., 2018. 3. ATILH (Association Technique de l’Industrie des Liants Hydrauliques) – https://www.infociments.fr/ 4. BE-CERT – https://www.be-cert.be/en/accueil/

About the author Dr Caroline Woywadt has been Director – Process Technology at Gebr. Pfeiffer since 2011. After graduating from RWTH Aachen, Germany, with a degree in Mineral Processing and a PhD in the field of grinding, she worked as a Process and Quality Control Manager at cement grinding plants in Germany and Poland, as well as a Product Manager for grinding products.

Table 2. Properties of exemplary cements produced in MVR and MPS mills. Cement type acc. EN 197-1 Blaine in cm²/g

NC in %

2d in MPa

7d in MPa

28d in MPa

CEM I

3680

27.7

46.3

60.2

CEM I

5050

36.9

52.6

63.3

CEM I

4780

26.5

35.2

47.9

60.1

CEM I (3% Limestone)

5070

29.6

33.8

48.9

59.5

CEM I (3% Limestone)

5150

30.5

37.6

50.4

60.8

CEM I

5000

35.1

51.2

61.8

CEM I (5% Limestone)

3800

25.4

27.7

48.2

61.8

CEM I (0.5% Limestone)

3500

26.0

24.3

37.2

48.2

CEM I (5% Limestone)

4900

25.5

33.0

63.0

CEM II/A-L (17.5% Limestone)

4400

27.2

46.2

60.4

CEM II/B-P (28% Pozzolana)

4180

28.0

22.0

33.6

47.7

4140

20.0

40.9

57.2

CEM II/A-M (6% Limestone, 6% Pozzolana)

5130

29.4

43.9

56.3

CEM II/B-S (23% GBFS, 4% Limestone)

4610

28.0

30.2

45.6

57.3

CEM III/A (45% GBFS)

4450

29.5

17.0

52.0

CEM III/B (70% GBFS)

5500

30.6

27.7

51.7

Strength in acc. to EN 196-1 Normal consistency NC in acc. to EN 196-3

CEM II/B-M (12% Limestone, 12% Pozzolana, 2% Flyash)

World Cement September 2021

Sathish Krishnamoorthy, FLSmidth, outlines how a new heavy-duty roller breaker helped to eliminate clinker crusher blockages at CalPortland’s Oro Grande plant.

Californi crushin

alPortland was experiencing problems with the clinker crusher at its Oro Grande plant in California. A couple of times a year, a big boulder would come through the cooler and block the hammer crusher, forcing the plant to shut down both the cooler and kiln in order to clear it. As a plant producing 6600 tpd of clinker, the lost production time was costly – sometimes amounting to millions of dollars over a calendar year, not to mention the safety risks involved with

entering the cooler. On top of that, the hammer crusher needed regular maintenance to replace wear parts and it was using a lot of power. The plant needed an alternative solution. However, CalPortland’s clinker crusher problems were solved by a new Heavy-duty Roller Breaker (HRB), supplied and installed by FLSmidth. The company’s one-stop-shop service was able to save the customer time and money, ensuring the successful completion of the project within the scheduled shutdown.

How it works: Heavy-duty Roller Breaker (HRB). Sub-25 mm clinker falls through the gaps between the transport rollers, while the bigger lumps are conveyed forwards onto the crusher rollers. The first of these is the ‘dropped roller’, which sits slightly below the horizontal plane of the other rollers. This one rotates clockwise, while the final crusher roller rotates counter-clockwise, pulling the oversized clinker into the nip where it is crushed between the teeth of the cast wear segments.

No boulder too big The plant had been in talks with a couple of suppliers about their problem for a while but eventually decided on a Heavy-duty Roller Breaker (HRB) from FLSmidth. “Our sister plant is already using the HRB from FLSmidth with great success, so we were confident in the technology. In particular, the differentiator compared to competitor models is what we call the ‘dropped roller’ for the first crushing roll, which gives that extra grip and efficiency when crushing the largest clinker lumps,” explained Kyle Smith, Chief Project Engineer/Project Manager, CalPortland. The HRB can handle clinker boulders up to 1.5 m. It features a series of transport and crushing rollers that allow the right sized materials to pass through and crush larger materials down to a pre-set size. For Oro Grande, the HRB 414 was chosen to fit within the cooler width. This model consists of two transport rollers and two crushing rollers that are electrically driven.

A low maintenance solution

The HRB can handle clinker boulders up to 1.5 m in size.

A significant improvement for health and safety. 22

HRBs deliver an effective, low-wear crushing process due to their lower speeds of operation at 6 – 8 rpm – a slow, persistent grind. In contrast, hammer crushers use a striking motion that sends bits of clinker flying around the crusher, causing wear. In a HRB, if the load gets too high, the crusher rollers reverse, stop, then resume their usual motion, repeating the process until the blockage is cleared. Instead of very high annual maintenance costs of up to US$100 000 to maintain the hammer crusher (including labour and parts), the cast wear segments have an expected life of at least five years with very minimal maintenance – a significant saving. Additionally, workers do not have to go into the cooler to clear it – a vast improvement for health and safety. Power consumption is also much lower, at around 100 HP compared to 150 HP installed with a hammer crusher. Not only is this a cost-saver, but it is also in keeping with CalPortland’s ENERGY STAR partner status. Saving energy is a priority for CalPortland, and the company is always looking for ways to make its plants more energy efficient, and more sustainable. The power savings were a motivator for the company with this project, as was the anticipation of fewer kiln stops, which have a significant environmental impact on top of the monetary cost. World Cement September 2021

Installation Installation of the HRB was scheduled for the plant’s annual maintenance stop in January 2021. “These types of projects are commonly contracted out to local teams. However, we decided to have FLSmidth Sioux City – our in-house service and installation team – take on everything except the electrical installation,” explained Sathish Krishnamoorthy, Head of Service Sales – NAMER Cement. “We know the equipment best, so it makes sense for us to take ownership of the installation process, providing a one-stop solution for our customer. Also, we wanted to be on-hand in case of any questions or problems during installation.” This was despite all the restrictions related to the pandemic. “We were very impressed by the way they handled everything,” said Kyle. “They were diligent, safety-conscious, and mindful of our need to get the plant back online as soon as possible. It was really good to have such a strong FLSmidth presence onsite for the installation.” During preparations for this project, CalPortland had also been in talks with FLSmidth about purchasing a KilnLoq® inlet probe with hot/wet measuring capability. “As well as being more robust, the KilnLoq gives the plant a much better oxygen, CO reading that can then be used to optimise the kiln, by balancing the air flow split between kiln/calciner, which will also help to reduce fuel consumption,” explained Sathish. “It’s a relatively small project that can have a very big impact.” Since the FLSmidth crew was already onsite, the company offered to install the KilnLoq at the same time as the HRB, saving money on bringing in additional crews. CalPortland was impressed with the results of both projects. Crucially, these projects were completed on time and within the company’s limited shutdown window, thanks to FLSmidth’s commitment to the deadline and the collaboration between FLSmidth and the CalPortland team. The HRB started up at the end of January and in March, CalPortland saw a boulder come through that would certainly have blocked the old hammer crusher, forcing them to shut down the cooler and the kiln. The company has experienced record numbers in its uptime and believes that the two projects have been instrumental in this.

How it works: KilnLoq laser gas analysis system. The system measures gases such as CO, NO, SO2, CO2, HCl and O2 at the kiln inlet, enabling kiln operators to optimise fuel consumption and clinker quality. The KilnLoq also features the unique One Pipe design for easy cleaning and very low maintenance, ensuring maximum uptime.

In-house service and installation team.

The KilnLoq HW Laser Gas Analysis system.

About the author Sathish Krishnamoorthy is the Head of Sales Support and Services at FLSmidth, North America. September 2021 World Cement

Installation of the HRB 414 was completed within the shutdown window. 23

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lobal bearings innovator, Bowman International, has launched to market a split roller bearing with substantially higher radial and axial load capacities. Ideal for applications such as screw conveyors, the new Bowman Advanced Split Roller Bearing offers up to 75% higher radial load capacity and up to a 1000% increase in axial load capacity in both directions.

Ian Breeze, Technical Director for Bowman, comments on the significance of this innovation: “For the first time, plant builders and maintenance engineers working in the cement industry can specify a split roller bearing that does not rely on race lips alone to accommodate axial force in high-load applications. The new Bowman Advanced Split Roller Bearing comprises two independent 3D-printed axial bearings designed to accommodate greater loads, improving system performance with less maintenance and reduced unplanned machine failure. “In fact, compared to other market-leading split bearings, the Bowman Advanced Split Roller Bearing increases bearing L10 life by up to 500%.” Further enhancing the performance of this revolutionary split roller bearing is a patented triple labyrinth extended seal which not only offers a tighter seal than other split bearings, but also reduces the need for costly removal, machining or replacement of worn shafts. Instead, engineers can simply fit an extended seal onto an undamaged part of the shaft, without compromising performance and without the need for extended downtime. Thanks to its high thrust capacity and increased radial load capacity, this bearing can be specified to replace solid spherical roller bearings in rotating machinery, delivering up to ten times faster bearing change times than previously possible for these applications. “When space is limited, engineers often need to disconnect the coupling and move other equipment, such as motors, gearboxes or pumps, out of the way before they can slide solid bearings off the shaft for replacement or maintenance,” explains Ian. “Split roller bearings can be assembled radially around the shaft, eliminating these additional logistical challenges and making maintenance and replacement a lot faster and more cost-effective. To further enhance time and cost savings, the Bowman Advanced Split Roller Bearing uses the rollers to lock the two cage halves together, eradicating the use of small and easy to lose clips and other locking components.” Alongside the significant increase in radial and axial load capacity, this new bearing design offers a range of additional installation and performance benefits, such as larger diameter screw sizes to accommodate increased capabilities for the clamp rings, cartridges and pedestals and roller pockets with cavities to hold the grease against the rollers. As part of the Advanced Split Roller Bearing portfolio, Bowman offers a range of dimensionally interchangeable retrofit products that fit directly into the existing bearing housings, even from competing bearing brands, to quickly and cost-effectively improve radial and axial load capacities. There is a choice of additional IoT-specific functionalities available and bespoke adaptations can be accommodated within fast lead times. Ian concludes: “Bowman is a proud innovator of bearing solutions that solve real industry issues. We are the first manufacturer to create a split roller bearing capable of increasing the lifespan and performance of high-axial systems and thanks to the production benefits of 3D printing, we have been able to deliver this product to market at a price point up to 20% lower than other leading split bearings.” For more information on Bowman’s new Advanced Split Roller Bearings, search ‘Bowman split bearings’ online. Advertisement Feature

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TAKING ADVANTAGE Liran Akavia, Seebo, explains how AI can help cement manufacturers to reduce emissions, whilst maintaining or even improving their production process efficiency and key business KPIs.

ecarbonisation has gained increasing importance over the past decade, and continues to occupy the minds of cement manufacturing executives. From improving energy efficiency to alternative fuels and clinker alternatives, cement manufacturers have a number of options at their disposal. Of course, many of these options are only as viable as local and national governments make them, but still, the race to net-zero is progressing at a global level. However, there is a problem. Cement manufacturers need to produce as much high-quality cement as possible, to meet demand and beat out the competition, or in fewer words – to be profitable. But if they use less energy, or switch to less ideal fuel or clinker alternatives, will they be forced to compromise key KPIs like clinker quality and kiln throughput? This tension between profitability and environmental protection lies at the heart of the issue of decarbonisation. Cement manufacturers cannot be expected to cut emissions at the expense

of their business. While this might rankle many die-hard environmentalists, it is simply a reality – for better or for worse. But is there a way to do both? The answer is yes. Cement manufacturers can both reduce emissions, and still maintain or even improve their production process efficiency and key business KPIs. At a recent panel discussion, a senior cement manufacturer discussed how some of their factories boast alternative fuel rates of 90% and still continue to push the limits in terms of process efficiency. That might sound like a fairytale, but the ‘secret’ is actually quite straightforward. The production losses that harm cement manufacturers’ bottom line – like unstable kiln throughput, clinker quality and energy inefficiency – usually stem from the same process inefficiencies that cause higher emissions levels as well. So, if these process inefficiencies are eliminated, it is possible to reduce quality, throughput and energy losses, and bring down carbon emissions at the same time.

Consistent kiln stabilisation is key – but can it be done? Stabilising the kiln at optimal levels is almost always the key. In fact, kiln instability is one of the greatest, if not the greatest challenge when it comes to reducing process-driven losses in areas like quality and throughput, and it is also a major cause of inefficient energy usage and high emissions. High fuel and energy consumption, product quality and throughput issues, clinker quality issues, high maintenance costs, kiln feed variances and high NOx and CO2 emissions are all problems usually related to instability or inefficiency at the kiln. But kiln stabilisation and optimisation is a never-ending battle. There is no ‘lightbulb moment’, when the process expert suddenly realises what is going wrong, fixes the problem, and waltzes off into retirement. Instead, the struggle begins anew each day, complicated by things like raw material variances and competing KPIs (like quality and throughput on the one hand, and energy costs and emissions on the other). In reality, it seems impossible to ever find the root cause of process inefficiencies.

The problem: Cement factories are reliant on human decision-making The underlying issue is the complexity of the process itself. There are simply too many factors and variables for human beings to process. Even the most experienced and intelligent process expert cannot possibly analyse all the data, all the time, while keeping track of all the complex interrelationships between different data tags and points within the production line. Process experts and production teams make dozens of critical, process-related decisions every day. These decisions can certainly be enhanced, informed and executed via analytics platforms, measuring tools, expert systems and so on. But ultimately, the decisions are made and carried out by human beings. This is an inherent limitation, as every person approaches a problem with their own biases and preconceptions. It is natural that when approaching something as complex as a cement manufacturing production line, human beings cannot possibly consider all the options at all times. Engineers and experts have no choice but to conduct ad-hoc analyses based on their own past experience, knowledge and, in some cases, intuition. Often, this works, but other times it does not, at least not continuously, as lines are constantly changing. So even a correct decision or analysis today might not be correct tomorrow – or even in a few hours’ time!

Limitations of expert systems Of course, in practice, cement manufacturing is not done entirely manually. In particular, expert systems have become an important automation tool for cement manufacturers around the world. Although expert systems do provide great value, they have a number of significant limitations. Dependence on human bias Expert systems are programmed by process experts and engineers. They are a closed-loop system and will do exactly what they are instructed to do. But what if the calculation itself was incorrect? What if a particular factor further upstream or downstream should have influenced that calculation, but was not taken into account? Siloed (asset-focused not process-focused) Expert systems are meant to regulate a particular asset or point within the production line, and they can do that very well. However, they do not take into account the entirety of the production process itself. The problem is that the optimal settings for a particular asset or point in the line may appear to fall into a certain range when considered by itself – but when considered together with other data tags, the situation might look quite different. For example, the ‘ideal’ speed of the kiln might change depending on the raw material variances that day. Expert systems cannot adapt to changes Expert systems use closed loop models, which do not update continuously. Process experts build the model once and it remains constant. On the one hand, an expert system cannot react to all the dynamic changes on the line – whether further upstream, downstream or within that asset itself (say a change in temperature or moisture). On the other hand, process experts cannot reprogramme the expert system each time those factors change. This is due to two factors: firstly, because programming the expert system is a lengthy, resource-heavy and expensive process, and secondly, because process experts are not always aware of a specific change on the line or its implications in the first place.

The solution: AI-driven decision-support tools Artificial Intelligence can effectively free cement manufacturing processes from the limits of human capabilities, by conducting real-time, multivariate analysis of all the data, and providing clear recommendations and alerts on a user-friendly interface. Seebo uses

World Cement September 2021

process based artificial intelligence for cement manufacturers. This is not closed-loop automation; Seebo is a decision-support tool that is constantly providing cement manufacturers with the information they need to make the right decisions – whether directly on the line, or indirectly via expert systems.

Reducing emissions 12% while preventing quality, throughput and energy losses To illustrate this approach, the following is an example of a cement manufacturer that was struggling with kiln amps inefficiencies. This was causing a variety of production losses, like kiln feed variances, lower throughput, energy inefficiencies and quality issues. Intriguingly however, some 40% of the time, this manufacturer still achieved higher-than-average efficiency rates. Many of the cement production lines Seebo works with are clearly capable of achieving the desired efficiency range, which is why they actually are more efficient some of the time. They do not need to invest in new assets or equipment, or overhaul their process. The potential is already there – it is just being held back by unseen inefficiencies.

Revealing the hidden causes of process inefficiencies Using automated root-cause analysis, process experts were able to identify the hidden causes of the manufacturer’s production losses, and gain clear recommendations as to how to prevent those process inefficiencies. Those recommendations were translated into real-time alerts, so the production teams knew as soon as inefficiencies were detected. Firstly, Seebo unified all of the disparate data sources from the production line into a single schema, where it was enriched and cleansed. This included all relevant data related to the process, from raw material data, to process and quality data, to data on weather conditions and alternative fuels characteristics. Next, the algorithms were taught to understand the entire production process, using Process-Based Artificial Intelligence™, which embeds the algorithms with the context of the unique plant topology, and expertise in the relevant cement manufacturing process. This enabled the algorithms to navigate through the unique complexities of each production process and truly understand the data in-context, providing a continuous, multivariate analysis that delivered clear information, eliminated data blindspots, and revealed important new insights into the

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production process that were previously hidden amongst the data. These ‘process-based’ algorithms can now conduct automated root cause analysis, continuously analysing all the data tags, including the complex interrelationships between them. The team can now identify process inefficiencies that were previously invisible to the human eye. For example, the team discovered that when the cyclone material temperature was above 800˚, and at the same time the kiln oxygen level was between 1.5% and 2%, the likelihood of a problem with the kiln amp increased significantly. This is a hugely important insight that the process experts could never have figured out on their own, since both of those tags remained within their permitted ranges. It was only the unique combination of those two specific ranges of tag values that was causing the losses.

Continuous process mastership with AI Armed with this new understanding, Seebo created a set of Predictive Recommendations, which identify the optimal process settings. For example, the team has now recommended optimal values for the cyclone material temperature and kiln oxygen level, to minimise instances of kiln

amps inefficiencies as much as possible without negatively impacting other production parameters. These recommendations are then turned into Proactive Alerts, which are delivered to the production team via a simple, intuitive screen as soon as the related process inefficiencies occur. The alerts include a clear description of the root-causes (e.g. cyclone material temperature above 800˚ and kiln oxygen level between 1.5% and 2%), as well as a set of Standard Operating Procedures, so production teams can know exactly what to do to fix those issues before losses occur, and when to act. Using these new insights, the manufacturing teams were able to significantly stabilise the kiln, resulting in an 11.9% reduction in emissions. And of course this also translated into the company’s business KPIs, for example they reduced energy costs by 5.6%, equivalent to €521 000. Clinker quality also increased by 4.2% and kiln feed capacity increased by 3.3%, resulting in €780 000 extra profit on a single line.

Conclusion

There should not be any contradiction between running a profitable, efficient cement production line, and reducing its carbon footprint. High emissions and high production losses usually stem from the same process inefficiencies; remove or reduce those inefficiencies, and both areas will improve drastically. Of course, this is no ‘simple’ task. It requires hard work, commitment, focus and one more crucial ingredient: AI. But those ingredients are all readily available, and cement manufacturers who take advantage of them in the right way are the future of the industry: Greener, more efficient and already moving ahead of the Every aspect of cement production ultimately relies on human competition. decision-making.

About the author

Seebo automated root-cause analysis. 32

Liran Akavia is the COO and co-founder of Seebo. He is a serial entrepreneur and sales leader who specialises in the fields of AI and manufacturing – particularly in reducing waste and quality losses. Before founding Seebo, Liran co-founded and led Playfect, which manufactured millions of gaming accessories that were sold across more than 35 countries, before being acquired in 2013. Liran has lived and worked in Israel, Australia, China, and France. World Cement September 2021

choice

Reinhard Ringdorfer, Unitherm Cemcon GmbH, outlines the benefits for cement producers converting to complete or partial natural gas firing.

he production of cement is one of the most emissions-intensive industrial processes, with 600 to 700 kg of CO2 produced for every one ton of cement. Globally, cement production accounts for approximately 5% of man-made CO2 emissions. Most of the CO2 generated comes from the decarbonisation of limestone, which is the main raw material in cement production. Only a small percentage of the total CO2 is produced as a result of the fuels used. While secondary fuels are considered

to be climate neutral, the CO2 from the primary or fossil fuels is subject to carbon tax. Therefore, it is in the best interest of cement producers to reduce the CO2 emissions resulting from the fuels used. The amount of CO2 produced during cement production is directly related to the carbon content of the fuel, while the heat content is determined by both the oxygen and carbon content of the fuel. When fuel is burned, heat is released as carbon and hydrogen are combined with oxygen.

The main component of natural gas is methane (CH4), which has a higher energy content than other fuels and therefore a relatively lower CO2 to energy content. In an efficient burner process, natural gas emits 50 to 60% less carbon dioxide compared to other fossil fuels. Additional benefits of natural gas combustion include excellent control behaviour in terms of measurement and turn-down ratio, and the fact that there is no chemical impact on the process using these fuels, due to them containing few or no impurities. Due to the properties of natural gas, special care must be taken, and several standards have to be adhered to when designing the burner and auxiliary equipment such as valve trains, control systems etc.

Burner design For the design of the rotary kiln burner, cement producers must distinguish between different applications: f Natural gas firing in a single fuel burner. f Natural gas firing in a combined burner. f Natural gas firing for start-up or support operation in a low percentage.

Figure 1. The M.A.S./SG burner is equipped with a ‘thermo-carbolysator’.

Figure 2. If natural gas is the dominant fuel used during cement production, the multi fuel burner will be designed with two gas channels, one for axial gas, and the other for radial gas. 34

M.A.S. Swirl Gas technology The Unitherm M.A.S./SG burner is a deviation of the Mono Airduct System, designed especially for 100% natural gas firing in a rotary kiln. The gas is split into the main gas (95 – 98%), which is fed through the flexible hoses instead of primary air, and the central gas. The flame shape is adjusted directly with the fuel and not with the primary air, which is a unique feature. Low-pressure air is used for cooling purposes only. This design allows for maximum flame control with a minimum consumption of air. The M.A.S./SG burner is also equipped with a ‘thermo-carbolysator’ (Figure 1), which is built into the burner’s central gas channel and is fuelled by approximately 2 – 5% of the total gas flow. A separate air supply is used to maintain the stoichiometric gas-to-air ratio. The thermo-carbolysator accelerates the process of the gaseous fuel heating until the gas is mixed with the secondary air. It provides continuous combustion without flame detachment during the heating up phase. Due to staged combustion, the burner improves the burning of bright materials such as white cement and lime. In the first combustion stage, the thermo-carbolysator mixes natural gas with low-pressure air inside the burner, ignites it, and forms a flame with the root located inside the burner. It provides an exceptionally stable satellite flame, due to the internal ignition of the gas. In the second combustion stage, the main gas flow is heated by the satellite flame to over 1000˚C under the shortage of oxygen near the burner nozzles. In such conditions, the main flame starts to glow, thus the thermal radiation affecting the clinker intensifies. Combined rotary kiln burner Natural gas can be fired through one or two gas channels in a rotary kiln burner. The design will be determined by the main fuel used during burner operation. Natural gas is usually injected into the burner at critical pressure, resulting in a velocity of more than 400 m/s. The momentum of the gas is usually two to three time higher than that of the primary air, which makes it complicated to adjust the flame with air. Due to this fact, it is very important that the gas flame can be adjusted by the fuel itself. If natural gas is the dominant fuel used during cement production, the burner will be designed with two gas channels, one for axial gas, and the other for radial gas (Figure 2). When using two gas channels, the flame will be adjusted in the same way as with the primary air. More axial gas creates a longer, slimmer flame; if the radial component is higher, the flame becomes shorter and wider. If natural gas is used only as back up fuel, the burner will be designed with one gas channel. The gas nozzle is designed with an opening at a certain angle to create a swirl. Additionally, the gas channel is World Cement September 2021

executed with an expansion joint at the cold end of the burner which allows for axial adjustment of the channel, including the nozzle. When pushed forward, a circular gap opens around the gas nozzle, introducing axial gas into the kiln and making the flame slimmer and wider. Operation with gas lance If natural gas is used only for heating up the kiln or as support fuel, a separate channel is often not necessary. The gas lance, or lances, can be either designed as separate units to be installed in a guiding tube (Figure 3) or as part of the central channel. Usually, the lance, or lances, are designed for up to 50% of the total capacity. The nozzle is designed with a special geometry consisting of bores in different sizes and angles to ensure optimum combustion and a stable flame formation.

Gas valve train The valve train must take care of all safety and control aspects, such as the safe start and stop of the gas operation, flow control, protection of downstream equipment from impurities and dirt, and supply of natural gas to the ignition burner. The valve trains are designed as compact units to allow easy identification of the parts and function on site. With the P&I diagram, the equipment list, the valve train drawing and the equipment numbering each part can be found easily. The valve train entrance Lock dirt and impurities out – different options are available depending on the application. A simple strainer is enough to protect the downstream equipment from a low volume of impurities in the natural gas. Other options include strainers or gas filters, or a combination of strainers and gas filters. Pressure control If necessary, the valve train can be equipped with a pressure regulator to keep the pressure constant and within the permitted limits for the downstream equipment. The maximum pressure is secured by a slam-shot valve triggered by high outlet pressure of the pressure regulator and is additionally secured by a safety-relief valve. Start/stop Safety shut off valves with intermediate ventilation guarantee the maximum safety and conformity with relevant standards. The valves are well tested and certified from manufacturers well chosen from Unitherm’s long-term experience in combination with the feedback the company receives from its valued customers and service partners.

Flow control The gas flow meter is a key component for continuous operation and fuel monitoring. A low to no maintenance requirement is combined with high accuracy and an excellent turn down ratio. The better the turn down ratio, the better the ignition of the burner at the starting condition. As an additional benefit, the burner may also be used for kiln drying operations with very low firing power. Monitoring Instrumentation is the key to constant and safe operation. Failsafe pressure monitoring needs to be applied to guarantee safety for operators and plant equipment.

Figure 3. The gas lance, or lances, can either be designed as separate units to be installed in a guiding tube or as part of the central channel.

Figure 4. Gas valve train.

Automation The BMS (Burner Management System) is located mostly directly on the valve train and is equipped with an HMI display to allow operation and troubleshooting directly from the valve train location. Different communication protocols (Profinet, Modbus over Ethernet, Profibus, etc.) or hardwired communication are available for communication with the plant PLC. As the system handles the fuels for the burner, (most likely gases like natural gas or biogas, or fuels oils like light or heavy oil) it is very important that there are clear regulations for how the system must be designed to make sure the hazard is kept to a minimum. For industrial thermal processes, these minimum requirements can be found in the EN746-2. According to the regulations (e.g., EN746-2) some relevant parts of the system (which also include the hardware/software of the BMS) have to meet a minimum SIL/PL and if a PLC is used, the PLC has to meet some extra regulations (EN ISO 13849 or EN 62061). For a plant operator who is not so familiar with these regulations, and does not have the requirements on site (e.g., a safety PLC) it is easier to buy a ‘package’ – a valve train with a tailormade BMS. Many plants have very old valve trains (sometimes self-built) with the functions of the Burner Management System programmed in a non-safety (most of the time the DCS) controller. Plant managers should be aware of this safety risk. Unitherm Cemcon’s Burner Management Systems are continuously developed further to meet the changing requirements of burners and of customers. The biggest benefit of the BMS is that it can be easily integrated via any fieldbus in the plant, as only the ‘START/STOP’ and fuel setpoint is needed to control the burner. All necessary other interlocks are already handled in the BMS and ensure a safe operation of the burner. For further diagnostics, all states, alarms, sensor readings, etc. are sent to the DCS to be visualised on the operator screen. The BMS continuously monitors all necessary pressures and sensors, as well as the flame signal. In the event of an unsafe state, the safety shut off valves are immediately closed.

Conclusion

Figure 5. Unitherm BMS visualisation. 36

If natural gas is available close to the plant, the conversion to complete or partial natural gas firing can be arranged rather quickly. Due to the easy handling of the fuel, a gas valve train with control system and a new or modified burner are sufficient for the fuel to be changed. Unitherm has installed numerous gas burners with supply systems around the world and works to improve the burner design with every new burner installed. World Cement September 2021

GETTING THE MOST OUT OF

M A IN N ANNCE CE I N TE T ENA

efractory maintenance, though vital, can often be a logistical and financial burden. This is especially true for cement and other large facilities that rely on kilns, coolers, preheater towers and risers for day-to-day operation. These facilities stand to lose upwards of US$50 000 a day in production if their refractory cannot stand up to the heat. To avoid unnecessary production loss, most facilities take on large-scale refractory removal and re-installation during annual maintenance shutdowns. However, managers know how quickly these precious weeks fly by with crews struggling to complete as many maintenance tasks as possible.

Establishing an efficient refractory removal and installation process is important for maximising productivity during these cycles, which is why many facilities employ innovative, specialised equipment that increases safety and minimises downtime during refractory maintenance. From robotic removal to fast, ergonomic installation, this article outlines how facilities around the world are increasing refractory maintenance efficiency.

Demolition robots

To gain earlier access to kilns as well as increase safety and productivity, some cement facilities employ heavy-duty, remote-controlled demolition robots for descaling and debricking applications.

The descaler demolition robot eliminates the need to have crews removing overhead refractory and can save facilities well over 100 hours in preheater tower applications.

With their position at the heart of the cement process, rotary kilns present a significant challenge to maintenance timelines when it comes to removing and re-installing refractory. Getting kilns up and running quickly is crucial to restarting production, but long cooldown times mean crews cannot even start descaling until well into shutdown. Additionally, descaling and debricking processes have traditionally relied on large crews with hand tools, such as jackhammers. This removal method comes with a number of drawbacks, including low productivity and increased risk of injury from equipment or falling debris. To gain earlier access to kilns as well as increase safety and productivity, some cement facilities employ heavy-duty, remote-controlled demolition robots for descaling and debricking applications. These ruggedly designed machines can withstand extreme temperatures, allowing facilities to begin descaling operations earlier than with any other method. The operator remains outside the kiln, away from the heat and the risk of falling debris. Demolition robots also offer an unbeatable power-to-weight ratio with the most innovative models performing on par with machines three times their size. Those in the 3500 – 8000 lb (1587 – 3628 kg) range can safely drive across the cooler using the facility’s kiln access ramp and are not heavy enough to cause damage to the kiln shell. Despite their compact size, industry-leading models can deliver up to 855 joules of hitting power at 550 to 1250 blows per minute. Top-tier demolition robots feature an innovative three-part arm, which requires less height to extend compared to a mini-excavator with monoboom. Height requirements for a demolition robot are only 72 – 84 in. (182.9 – 213.4 cm) in most cases. This is ideal for work in kilns and other confined spaces. With a vertical reach between 15.8 ft and 21 ft (4.8 and 6.4 m) and a horizontal reach between 14.4 to 20 ft (4.4 to 6.1 m), cement facilities are able to fit the demolition robot to their specific kiln. For one independent refractory contractor, adding a demolition robot to its crew significantly reduced overhead while increasing

World Cement September 2021

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tear-out productivity. Relying on the robot’s remote operation, the company virtually eliminated falling debris injuries, which resulted in a reduced experience modification rate (EMR) and lower insurance premiums. The contractor also reduced crew size for descaling and debricking by 75% while achieving removal rates up to 33 ft per hour (10 m per hour). Reallocated crew members were then able to increase productivity on other tasks, leading to a boost in overall efficiency. But kilns are not the only place robotic demolition is increasing productivity and safety for refractory removal. This method has also been applied to coolers and feed shelves. Additionally, industry-leading equipment manufacturers recently developed an innovative robotic solution for descaling in preheater towers.

Like kilns, traditional refractory removal in these vessels often involves handheld tools. However, preheater towers have an additional challenge – their vertical orientation. This requires crews to perform handheld breaking from scaffolding, resulting in long setup times, low productivity and difficult working conditions. Erecting the scaffolding system means a slow start to maintenance – once temperatures cool enough for crews to enter at all. More importantly, though, vessel design results in workers removing hundreds of tons of overhead refractory, making the process not only physically draining but extremely dangerous. A specially adapted demolition robot removes these hurdles, requiring zero physical contact and saving crews well over 100 hours in certain situations. The unit features the innovative, highly manoeuvrable three-part arm featured on some demolition robots. This is attached to the end of a platform-mounted telescopic boom. The boom is extendable by up to two sections, allowing for descaling in vessels up to 31.2 ft (9.5 m) in diameter. Personnel never need to enter the tower thanks to remote-controlled operation, eliminating the risk of falling debris, silica dust and other confined space hazards. Not to mention, the robot takes pneumatic equipment out of employees’ hands, reducing worker injuries and fatigue for lower operating costs. The descaler demolition robot can be set up in less than three hours, depending on preheater tower specifications, saving facilities considerable time and resources compared Hydrodemolition allows facilities to keep crews to scaffolding. Because it is based on a out of the most dangerous situations through heavy-duty demolition design, the descaler robot remote-controlled operation. Compact, highly versatile can also stand up to much hotter temperatures. Hydrodemolition robots can access confined spaces This allows facilities to begin tear-out operations with some units able to operate just 14 in. (35.6 cm) when the ambient temperature reaches 176˚F from the surface to be demolished. (80˚C), advancing their maintenance timeline significantly. The descaler demolition robot allows cement facilities to tackle refractory removal in other areas as well, including cyclones, calciners, pyrotops, kiln inlets, ‘goose necks’ and gas risers.

Hydrodemolition robots

Bricking machines with a dual arch offer increased productivity by permitting installation of a second ring of bricks while the first is being keyed. This design features a cut-away section at the front of the arch that provides an unobstructed area to place key bricks. 40

Hydrodemolition robots provide another efficiency-enhancing solution for refractory removal in tight spaces such as risers and transfer lines. This method uses high-pressure water jets to break up refractory materials without damaging embedded V-anchors, hex mesh or the steel mounting surface, resulting in faster, more cost-efficient maintenance. As with demolition robots, employing hydrodemolition allows facilities to keep crews out of the most dangerous situations through remote-controlled operation. Compact, highly versatile hydrodemolition robots can World Cement September 2021

access confined spaces with some units able to operate just 14 in. (35.6 cm) from the surface to be demolished. Additionally, this water-based removal method eliminates silica dust while leaving a cleaner surface that does not require additional sandblasting or power washing. This not only increases safety, it also contributes towards accelerating maintenance timelines. Hydrodemolition robots also provide a significant productivity boost compared to hand removal methods. At 18 000 psi, Hydrodemolition equipment can provide 100 times the productivity of handheld equipment, removing 9.5 ft3 of refractory per hour compared to just 0.1 ft3 with a 15 lb pneumatic hammer. This productivity, paired with the robot’s ability to work on vertical, horizontal, overhead and curved surfaces without tiring, means facilities can make significant gains during refractory removal for a faster return to operation. To maximise Hydrodemolition productivity and overall versatility, many facilities and independent contractors partner with equipment manufacturers to provide solutions tailored to their unique needs. There are several hydrodemolition options available for refractory removal, but not all provide the same level of control and productivity. One important variable that can lead to gaps in efficiency is the distance between the nozzle and the refractory surface.

Simple automated setups, such as those used in risers that feature a rotating nozzle and stabilising ring, might have several inches between the nozzle and the refractory surface. This distance results in a significant loss in power by the time the water reaches its mark, causing operators to compensate with a higher flow rate. A high-tech robotic system operating within 0.5 in. (1.3 cm) of the refractory surface, on the other hand, does not suffer this loss of power, creating better removal rates per pump hour, as well as better fuel and water efficiency. Additionally, this type of system allows the operator to set parameters, including the lance speed and angles, as well as indexing, to optimise efficiency. Multi-purpose hydrodemolition robots can also be used in other areas of the facility for surface preparation and concrete repairs, providing better equipment versatility than single-use options. One such system is employed by a cement plant in Oklahoma for repairs on its concrete structures, including silos and foundations. The impact-free hydrodemolition process eliminates microfractures and vibrations for a more durable repair in sensitive environments.

Refractory installation Increasing efficiency for removal is only half of the equation, though. To get

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production up and running again quickly, facilities also need to maximise productivity during refractory installation. Unlike removal, there is no high-tech replacement for a master mason, meaning installation can only move as fast as bricking crews. Most masons employ a bricking machine in rotary kiln applications, which offers increased productivity and better ergonomics for fast, high-quality refractory installation. Efficiency starts with the bricking machine setup. Those constructed of strong yet lightweight modular aluminium components are easy to maneuver into the kiln and can be assembled in just 60 – 90 min. by an experienced crew. Steel models might take 6 – 8 hrs and require additional support equipment. Modern bricking machines feature a pneumatic arch that raises bricks into place against the kiln shell and holds them there, eliminating the more physical aspects of traditional refractory installation. Additionally, the pneumatic arch system provides superior quality results that can extend the longevity of refractory by as much as 25%. Bricking machines with a dual arch further increase productivity by permitting a second ring of bricks to be installed while the first is being keyed. This design features a cut-away section at the front of the arch that provides an unobstructed area to place key bricks. Machines without this feature force installers to try to find other ways to reach around the arch, reducing installation speed and, in some cases, quality. For one cement plant in the United States, incorporating a dual arch bricking machine with a cut-away section decreased maintenance downtime by 44%. Bricking machines from leading manufacturers allow masons to tailor equipment to fit the kiln and their particular process for a more comfortable experience. Machines are available in a variety of sizes. Recently, a stair-stepped deck design was released that allows

support equipment, such as skid steers, to drive under the machine for more efficient brick management. Specialised equipment can also make maintenance more efficient in vertical vessels. Custom-designed suspended platforms are being used by cement and other facilities as an innovative solution for brick and spray refractory installation in lime kilns, precalciners, cyclones, ISAMELT furnaces and preheater towers. These lightweight, heavy-duty metal platforms are erected inside the vessel and raised or lowered using manual or electric hoists for hassle-free maintenance and relining applications. Suspended platforms eliminate the need for complex scaffolding systems. Those featuring a modular design and pin-together construction can be set up in as little as two hours. For one cement facility, using a suspended platform to install a drip tube in a cyclone eliminated five days of double shifts, saving an estimated US$15 000/hr in downtime. Additionally, suspended platforms provide ample surface area – and capacity – for personnel, tools and materials such as refractory brick, gunning equipment and other necessities. Refractory installation can progress faster since there is no need to hoist supplies up and down; everything is close at hand and there is plenty of room to move. This also reduces the physical strain on workers and the risk of falls, resulting in a safer work environment and decreased overhead.

From start to finish When it comes to refractory maintenance, what comes down must also go back up before the job can be considered complete. Increasing efficiency throughout the process means facilities can start up production that much quicker. Working with specialised equipment from innovative manufacturers can greatly increase productivity, safety and overall quality of refractory maintenance. Whether it is a robotic solution for removal, a custom-designed platform or bricking machine for installation or a combination of both, cement and other facilities can revolutionise refractory maintenance by investing in the right tools.

About the authors Lars Lindgren is the President of Brokk Inc., the North American branch of Brokk, a leading manufacturer of remote-controlled demolition machines and attachments for 45 years. He also oversees North American operations for Aquajet, an industry leader in Hydrodemolition machines and solutions. Lindgren has more than 24 years of industry and leadership experience. Custom-designed suspended platforms are being used by cement plants and other facilities as an innovative solution for brick and spray refractory installation in lime kilns, precalciners, cyclones, ISAMELT furnaces and preheater towers. 42

Heather Harding is the Managing Director for Bricking Solutions, a world leader in kiln refractory installation solutions. She has served in leadership positions in the industry for more than 12 years. World Cement September 2021

READY FOR

RAPID RECOVERY

& REPAIR Herbert Hoenl, REFKO, explains how successful and long-lasting emergency rotary kiln repairs can be achieved, resulting in safer operation of the kiln until a planned shutdown can take place.

orldwide, the demand for cement remains at a high level. Modern, more environmentally friendly production methods for cement are increasingly conquering the market. This is leading to a reduction in ‘classic’ cement plants and a concentration on plants that are converted according to the most modern environmental aspects or, in some cases, directly to new kilns. In such plants, higher quantities of cement have to be produced by fewer cement kilns, and a high degree of operational safety is required. Downtimes must be shortened and kept to a minimum, and unscheduled downtimes must be completely avoided.

In particular, emergency situations, such as sudden hot spots that arise on the rotary tube, have in the past often led to longer unscheduled downtimes in order to replace the worn areas with new bricks. It often happens that in such emergency situations, not enough bricks are available for repair and are not easily procured on such short notice. Plants may also find that there are no skilled or trained installation personnel or required installation machines (e.g. DAT devices) available at the time. In this case, emergency solutions may be required, such as cooling or other measures in the running process. Not infrequently, however, the

continued operation of a kiln with brick damage in the rotary tube then leads to serious subsequent damage, for example deformation of the steel shell, problems in the kiln drive areas, etc. Therefore, the process reliability of the kiln system is at stake. This is where the REFKO Recovery System comes into play. This material and system development allows a hot spot situation (caused by brick damage) on the rotary kiln to be quickly rectified and enables safer operation of the kiln until a planned, usually annual, shutdown. The following example will show how a repair was carried out at a hotspot area using a modern designed gunning refractory concrete, based on magnesite/spinel. This led to a short shutdown that allowed the cement plant to operate safely again and without any problems until the next regular and planned annual repair shutdown. The special binding system and selected material composition of the REFKO Recovery System provides a good bond with the existing worn out lining. The installation can be completed with classic dry gunning machines, which are available worldwide.

Case study Lining sketch.

Premature wear of MgO/Spinel bricks.

In the area of the burning zone, in a kiln with a length of approximately 60 m and a diameter of approximately 4 m, a premature wear of the MgO/spinel bricks occurred. The affected areas were cleaned well with compressed air. All loose adhesions and dust deposits were also removed as much as possible by this process. Further pretreatment of the worn brick lining may also be necessary in cases such as these, depending on the damage pattern. The repair areas prepared in this way are usually divided into installation fields. Depending on the desired layer thickness, the use of anchors can also be considered. This must be decided individually ‘on site’. REFKO does not recommend gun layers below 5 cm thickness.

Sketch of a rotary kiln. 44

World Cement September 2021

REFRACTORIES AND MORE FIRST IN QUALITY !

Unshaped monolithic materials

Fast heat up

Ceramic shock blower

Bull nose preshaped block system

Anchor concept: Seal achor

Preshaped block System

NEU / NEW REFKO MIX Guide APP

Hilfestellung zur richtigen Verarbeitung unserer Produkte l Support for the correct handling of our products REFKO Feuerfest GmbH l Concordiastraße l D-56235 Ransbach-Baumbach Tel: +49 (0) 26 23 - 2075 l Fax: +49 (0) 26 23 - 1738 l E-Mail: info@refko.de l www.refko.de

Cleaned surface and marking of the installation fields.

Example of a commercially available dry gunning machine. 46

The installation fields are separated from each other by working joints and the joints should follow the stone joints. This is necessary to give flexibility to the mechanical loads in the heating up and operational phase, as well as the thermal expansion of the monolithic layer. To achieve optimal mechanical stability, complete rings should always be gunned. The selective repair of damaged areas is not advisable. The gunning of the REFKO Recovery MG concrete was carried out in this case with a commercially available dry- or respectively rotor-gunning machine. These machines are in use worldwide and can be easily organised for emergency repair work. The REFKO Recovery products do not require any special machines that can only be operated by specialists. The only special feature is the use of a high-pressure membrane spray nozzle, or the ‘REFKO nozzle.’ In combination with a high-pressure water pump, a practically dust-free gunning installation can be achieved and this special refractory concrete can be gunned with good results. The REFKO nozzle and high-pressure water pump are now standard in many cement plants and installation companies. If, however, no REFKO nozzle and/or high-pressure pump are available, equipment will be provided by REFKO. Also, during the first installation of one of REFKO’s technical service co-workers will always be on site. After setting, the concrete developed a stable connection with the subsoil, so that the furnace could be turned to the next mounting position without any problem. REFKO had to deal with very low outside temperatures, but even under these conditions, the concrete could be safely installed. 24 hours after completing the gunning, the kiln was ignited again. The binding system of the REFKO Recovery MG System also allows for a quick restart of the furnaces. Furnaces can be heated according to the respective plant-specific specifications for re-starting. The heat-up to operating temperature and the first material feed in the repaired area went ahead without any problem. No material spalling was detected in the kiln during the start phase. After reaching the operating temperature, the repaired zone was monitored with thermal cameras throughout the whole World Cement September 2021

kiln journey. At no time were new hotspots About the author detected in the repaired area. Herbert Hoenl is Managing Director at REFKO After almost four months it was time for the Feuerfest Gmbh. Herbert studied Materials annual, planned shutdown of the cement kiln. Engineering at the Koblenz University of Applied The repair area was still completely preserved. Sciences, and graduated as Dipl.Ing (FH). A sintering connection with the subsoil could be Herbert has worked at REFKO Feuerfest GmbH detected in the post-mortem samples. No larger for 30 years. He started in the R&D and QM or more problematic formations of build-ups were department and has since remained personally detected. If a planned shutdown had not taken involved in the development of new refractory place, the repaired area could have lasted much materials, product concepts, and technical longer. solutions. The cement plant operator He is also boardmember of the DGFS was satisfied with the repair (Deutsche Gesellschaft Feuerfest- und using REFKO Recovery. The REFKO Recovery Schornsteinbau e.V. /German Association of product and system range is made up of Refractory & Chimney Contractors). products for quick repairs in all hot areas of a cement kiln. Like for the rotary tube repair described above, REFKO Recovery products can be applied to the worn-out areas. The insulating kiln layers can be completely preserved. As a result, less material is required for the restoration of the desired wall thickness than with a completely new installation. There is also likely to be less outbreak material. REFKO nozzle and high-pressure water pump. The type of repair and installation described in this article uses a resource friendly method. This method also significantly lowers expenditure on demolition- and installation-times. REFKO Recovery ZSI solutions can also be heated quickly, at up to 75˚C/h without holding times. This means that the kiln can be quickly put back into operation after a repair.

Results With the REFKO Recovery MG products based on Mgo/Spinel, successful and long-lasting repairs can be carried out in the rotary kiln area. Together with the REFKO Recovery products for the static areas of a cement kiln, a product and system portfolio is available which optimally meets the modern requirements for safe and fast repairs. These modern product developments show that by repairing existing lining, breakout is avoided and less ‘fresh’ material is needed. In addition, savings can be made due to lower assembly costs. New developments in the field of monolithic refractory materials can save resources and can represent a small step in the reduction of the cement industry’s CO2 footprint. September 2021 World Cement

Almost dust-free gunning of REFKO Recovery MG (left) and repair zone after installation (right).

Sketch of lining, with insulation and anchors. 47

THE BENEFITS

BRUSH

Mathis Menzel, Menzel Elektromotoren, explains why cement producers should forgo brush-lifting devices for slip ring motors in favour of sourcing high-quality, application-specific brushes.

lip ring motors are great for powering cement mills and crushers. In contrast to squirrel-cage induction motors, they provide the full starting torque from standstill and need no power electronics to get high-inertia applications started. This enables a rugged, long-lasting motor design suited for the most dust-ridden environments

at a competitive price. Slip ring motors feature carbon brushes as wear-and-tear parts that typically need to be replaced after a period of several months up to several years, depending on the application. These brushes, composed mostly of graphite and copper, allow the variation of the rotor resistance to achieve high starting torques. After motor startup, the external resistors are switched off. Conventionally, the brushes are in permanent contact with the slip rings. However, by installing short-circuiting and brush-lifting devices, they can be removed after motor startup in order to decrease wear and achieve much longer brush lifetimes. After the motor has reached the nominal speed, the rotor windings must be short-circuited, then the brushes can be lifted. This is intended to reduce maintenance requirements and save costs on brushes.

Original target applications To understand why the question of brush lifting arises at all, it is worthwhile to look at its historical background. In the past, applications for slip ring motors were much wider than today, as they have largely been replaced with squirrel-cage motors. For instance, slip ring motors were also used in applications that did not require high starting torques (like cement mills do) because of their low inrush current. Typical examples for such applications included water pumping stations in remote areas with a weak grid. These motors powered large pumps in practically uninterrupted continuous operation, with just a handful of restarts per year. In those days, brush quality was significantly lower than today, and the brushes wore down quickly. Brush lifting in those circumstances had the advantage that it greatly reduced maintenance requirements – the pump motor could be started up and left running for months on end. It was ideal for remote waterworks that operated mostly unsupervised.

are typically started up daily in contrast to once every few months. The motors are exposed to vibrations and dust, which exerts a lot of stress on any brush-lifting device. Also, staff are always on hand to check and, if necessary, swap brushes. It appears that the demand for brush-lifting devices in the cement industry is kept alive primarily through active promotion of this solution by a few specific motor manufacturers, who see it as a way to distinguish themselves from the competition. Menzel Elektromotoren does not recommend brush lifting for the cement industry because the benefit of reduced brush wear is too small to justify the additional cost for installing and maintaining the mechanisms.

Cost–benefit assessment

Within recent decades, brush quality has improved. Today, high-quality brushes with standing times of one-to-two years per set are available. The price of a customary brush-lifting mechanism will buy brushes for 15 to 20 years. The maintenance effort for regularly checking How does this apply to the cement and exchanging the brushes and cleaning the industry? slip rings is negligible. Plant staff manage this In the cement industry, the use cases and ambient in little time, and servicing can be scheduled to conditions are completely different. Main mills fit the production plan. In contrast, brush lifting requires complex measures and creates significant additional risks of motor failures. Short circuiting the rotor windings must be very well synchronised between the three phases and with the lifting mechanism. If not, an arc will form between the slip ring body and lifting mechanism upon lifting the brushes, and in many cases, the entire mechanism will be destroyed. Menzel’s experience with repair calls for motors with brush lifting is that in 90% of the cases, the lifting mechanism is the reason for failure. Brush-lifting devices introduce a number of additional moving parts into the slip ring chamber that can wear or jam. Different designs present various weak points. Figure 1. Sturdy slip ring motors without power Figures 2 and 3 show a device actuated by a electronics are used to drive raw mills. chain drive. This auxiliary drive, which is positioned on top of the slip ring motor itself needs proper maintenance. The hole through which the chain is guided into the slip ring chamber also allows dust and dirt inside. This can lead to scratching of the slip rings and overheating if dirt accumulates. A more modern design as seen in Figure 4 features a levered mechanism. In this case, Figures 2 & 3. Brush lifting requires various moving parts that create two auxiliary drives are additional risks of failure (left). In this design, the mechanism is installed inside the slip operated via a chain (right). 50

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Figure 4. Levered brush-lifting mechanisms and the necessary extra drives take up a lot of space and impair accessibility for maintenance.

ring compartment, along with several metres of cables as well as various switch boxes. Accessibility for maintenance is made difficult. If brush-lifting devices fail, this results in a complete destruction of the slip ring body and often of the rotor winding, too. Repairs for such a big failure take many weeks and cost almost as much as a new motor. Figures 5 and 6 show a dismounted short-circuiting and brush-lifting device of a smaller motor, again with a levered mechanism and with an auxiliary drive mounted outside the housing. This device had already caused trouble more than once. Eventually, after 20 years in service, it had blown up, effectively taking the motor out of service until it could be replaced. The device had to short-circuit a current of more than 1000 A. At the same time, the mechanics were subject to dust and vibrations. Eventually, the strain was too much, and there was a high fault current. Repairing or replacing the brush-lifting device would have been prohibitively expensive as well as being too time-consuming. Menzel quoted a motor without brush lifting, which the manufacturer could quickly configure for the application. Commissioning was only three weeks after the original motor failure. The customer was happy to be able to limit the machine downtime.

Getting the most out of brushes

Figures 5 & 6. This short-circuiting and brush-lifting device caused total motor damage through a high fault current. 52

Carbon brushes are pressed against the slip rings by springs. They must slide well in the brush holders and have even contact with the slip ring surface. Rocking and tilting brushes can cause sparking and brush fire with potentially devastating consequences. Brushes should be replaced when they are worn down to half their length because, beyond this point, the pressure will no longer be sufficient for good current conduction. Customers should always exchange all brushes of one motor at the same time, using only brushes from the same batch to avoid uneven wear. They should generally take care to buy brushes only from reliable sources, such as the original motor supplier, and not fall for poor-quality replacements at supposed bargain prices, which unfailingly have shorter lifespans and often cause costly damage. Motor manufacturers provide information on recommended brush exchange intervals. If in practice brushes wear down much faster than the recommended interval, dedicated analysis of the application by motor experts might show up possible corrective measures that will save money over time and increase the motor’s reliability. Brushes provide the World Cement September 2021

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best performance if the material composition is optimised for the application. Factors to consider include duty types as well as climatic conditions and even the height above sea level. Menzel has built up an significant wealth of knowledge in

Figure 7. These slip rings show severe damages in multiple places due to a brush-lifting device failure, arcing and flashover.

this field and will happily advise companies on brush selection. The German motor manufacturer regularly also provides customised brushes and has thus improved performance in various cement industry applications. Menzel manufactures large industrial motors – the company has a large stock of motors for all common applications and can also supply motors with brush-lifting devices, but weighs this decision very carefully against the kind of application to avoid unnecessary trouble in the long term. In its own slip ring motor series, Menzel has optimised various design details. The slip ring chamber is positioned between the motor bearings instead of externally. Therefore, the motor bearings can be exchanged without removing the slip ring body, which is often the cause for damaged windings or slip rings. This design does not require hollow motor shafts to connect the rotor windings with the slip ring body. In addition, it enables an overall shorter length of the motors. Since the bearings are situated further apart, the motors are also more vibration-proof. Two large service windows enable comfortable access to the slip ring compartment from both sides.

Conclusion

Figure 8. Different, application-specific material compositions ensure long brush lifespans in different climatic conditions.

Brush lifting avoids brush use, but at a high price. There are high additional costs for correctly installing and maintaining short-circuiting and brush-lifting devices. Especially in cement industry applications, there is no reason to employ brush lifting since the cost-saving potential is small and far outweighed by the risk of causing motor failures. Customers can avoid this risk and ensure higher availability of their motors by sourcing high-quality brushes and regularly servicing them – at comparatively little costs and effort. Optimal application-specific brush selection ensures longtime safe operation and minimal lifetime costs.

About the author

Figure 9. The slip ring compartment in a Menzel-designed motor without brush lifting provides easy maintenance access through two large service windows. 54

Mathis Menzel is the CEO of Menzel Elektromotoren and the grandson of the company’s founder. He has a degree in electrical engineering from the Technical University of Berlin. His university career included studies abroad, including at the University of California, Berkeley. After gathering professional experience in England, France, and Spain, he joined the family-owned company in 2005 as Chief International Sales Manager. In 2007, he joined his parents in the top management. In 2010, he became the company’s sole owner. World Cement September 2021

GREENER TIMES CALL FOR

GREENER MEASURES

Hans Conrads, PROMECON, considers how measurement technologies can be optimised in order to achieve more ‘green’ cement production.

he cement industry is one of the most fundamental to the world economy. Without cement, new construction projects for developing countries would be unthinkable and further growth and modernisation, even of the top industry nations,

is likely to fail. Wherever a country starts from grass roots to develop its economy, the erection of cement plants is one of the first things to be carried out. Cement production has grown into a global industry. However, the global cement industry has become a victim of its own success.

Cement production is not only essential, but it is also highly energy intensive, has hazardous pollutant emissions potential, and releases all of the bound CO2 in limestone, as well as in fired fuels. The good news is, however, that there is also potential for cement plants to reduce their

ecological footprints. Besides the technological changes that may be brought about in the coming decades, there is plenty of low hanging fruit that can be reached by fairly basic and simple optimisation steps in existing plants.

Measurement technology PROMECON has recently been focusing on a few very basic and some difficult measurement applications: f The measurement of hot and dusty gas flows. f The measurement of enthalpy flows. f The measurement of solid material transport in pneumatic conveying lines.

Raw mill application.

These measurements are key to many process problems in cement plants which can be optimised. This article will highlight the most important ones and how they can assist in the optimisation of the plant’s ecological impact.

Fan power reduction

Downcomer application.

McON Air Compact – PROMECON’s digital flow measurement systems. 56

Fan power is often the biggest drain of electrical energy and represents a large portion of the overall energy consumption in the cement plant. It is a common problem that fans in cement plants are not operated at their optimum set point. The result is an overdraught in many fans. The electricity consumption of a frequency controlled fan rises with its flow by the third power. Therefore, an overdraft of 10% will result in 27% higher power consumption. The excess power consumption has two major impacts: Firstly, it is costly, and secondly, it has a large carbon footprint, as most electric power comes from coal fired generation. A reduction in electric fan power thus has a direct ecological impact. PROMECON has helped to optimise fan power in main rotary kiln draught fans, raw mill fans, finished product mill fans, as well as waste heat recovery fans. These fans traditionally run without a drift free and stable flow measurement because of the dust impact. In many plants, the installed dP measurements are idle and not in use due to the large World Cement September 2021

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maintenance problems associated with them and operator reliance on other, more crude, values to best estimate a safe operation for the fans. The PROMECON measurement helps to provide an accurate value for the flow, allowing the reduction of fan power whilst keeping a safe operating margin.

Raw mill One big consumer of fan power is the raw mill. Raw mill operation relies on the fact that the bed depth of the raw material on the milling table is controlled. One big concern is the overloading of the grinding table, which will cause the mill to drown and then trip. The way to safely avoid this is to ensure a minimum gas flow through the mill. However, with uncertain traditional gas flow measurements, operators tend to overdraught the mill in order to be on the safe side. This can result in 10% – 15% higher flows as a consequence. An accurate and digital flow measurement will allow a much lower tolerance on the low flow limit and hence safer fan power. Installations of a raw mill at LafargeHolcim have revealed savings of 1 kWh/t of raw meal. This was equal to 150 kW for a 150 tph mill.

Downcomer The flow of gas through the rotary kiln is controlled by a large ID fan. Usually the control of ID fans results in a lot of process noise as the main control value, the O2 on the inlet, or the downcomer, has a long lag time, and hence causes larger long-term fluctuations of the ID fan power. The goal here is a steadier kiln operation. This goal has been achieved in many plants by the use of a PROMECON digital process gas flow meter. The exact and drift free gas flow value can be used in a cascaded controller to stabilise the ID fan flow in the short term, while the O2 measurement is still used in order for the O2 to remain at its target. The result of this control enhancement is a far more flat lined gas flow rate through the kiln, resulting in direct fuel savings of several percent, which can be over €2000 per day. As the fuel is a direct emitter of CO2 as well as other hazardous pollutants and dust, the impact will be significant. Also, the more flat lined operation of the fan has a significant impact on the electric power consumption, because of the non-linearity of the power curve of a fan. The fact that electricity consumption increases with flow to the third power means that any swinging of operation will result in excessive power consumption as compared to a stable operation. 58

Pre-calciner Modern plants have pre-calciners that are upstream close to the kiln inlet. They calcine the raw meal before it enters the kiln. Beside the hot gas from the kiln, they need an additional heat source in order to drive out the CO2 from the raw meal. For this, a fuel is burnt in the pre-calciner. This fuel can be either coal or secondary fuel. In order to burn the fuel in the pre-calciner, oxygen is needed. However, this oxygen is not available from the kiln, so the necessary combustion air comes from the tertiary air duct. The problem here is that pre-calciners can form large amounts of thermal NOx. In fact, a lot of the NOx that can be avoided at the main burner can later on be formed in the pre-calciner again. Authorities around the world have been very tolerant about NOx from cement plants thus far, but this tolerance is coming to an end, and plants are being forced to reduce their NOx significantly. One way to achieve this could be secondary measures such as SNCR or even SCR systems, which demand high investment as well as high operation costs due to their NH3 consumption. Another very cost-efficient way is to measure the fuel flow to the calciner as well as the tertiary air flow in order to adjust the oxygen flow to the pre-calciner. A better combustion control of the pre-calciner will result in a much lower thermal NOx formation as well as a lower NH3 consumption. The downtime of the pre-calciner can also be significantly reduced. There are further points for optimisation such as: f Optimisation of bypass gas flow. f Any and all recirculation ducts. f Direct measurement of cyclone gas outlet flow. f The waste heat recovery side. f Finished product mills. PROMECON will continue to explore the cement making process and find new solutions for clients worldwide to make the production of cement more ecologically compliant as well as cost-efficient.

About the author Hans Conrads holds an Electrical Engineering and Signal Processing degree from the RWTH University of Aachen, Germany. Hans has over 25 years of experience in the power industry as an entrepreneur and inventor of novel measurement systems to optimise the combustion of large steam generators. He also has multiple international patents and innovation awards and is the owner and CEO of PROMECON GmbH in Germany. World Cement September 2021

INDIA :

STRIVING FOR SUSTAINABILITY Dr. S. B. Hegde describes the major strides the Indian cement industry has recently taken towards achieving sustainability and a circular economy.

ndia’s vision is to become a superpower and to have a robust economy which is primarily dependent on the growth of its industrial sector, with cement being the most produced commodity. In India, the major cement consuming sectors include housing and real estate (65%), infrastructure (25%), and commercial and industrial development (10%). From 2018 – 2019, India had an annual cement consumption of 337 million t and this is expected to increase up to 550 million t by 2025. This increase is attributed to various developmental

schemes launched by the Government of India, including the Smart City Mission, Housing for All, Bharatmala Pariyojana, Pradhan Mantri Gram Sadak Yojana, Urban Transport Metro Rail Projects, etc. Aided by suitable government foreign policies, several foreign players such as Holcim, HeidelbergCement, and Vicat have invested in the country in the recent past. The per capita consumption of cement in India is 240 kg, which is well below the global consumption of 530 kg (DIPP, 2020). This signifies that there is a huge economic opportunity to cater to the unmet demand in future.

Significant improvements in plant operational parameters

The Indian cement industry and potential for a circular economy

Average ‘specific heat consumption’ and average ‘specific energy consumption’ in the Indian cement industry is 3.1 GJ/t of clinker and 80 kWh/t of cement, respectively, which is less than the global average of 3.5 GJ/t of clinker and 91 kWh/t of cement, respectively. Regarding the energy efficiency (EE) lever, many energy-efficient technologies have already been implemented in the cement industry, leaving little potential for decarbonisation. Additionally, to realise the leftover potential in EE, various technologies like waste heat recovery (WHR), installation of highly energy efficient coolers, grinding systems, and the use of variable frequency drives (VFD) in process fans etc., are being implemented in integrated plants.

The cement industry’s contribution to a circular economy mainly falls under two categories i.e. circular supply chain, and recovery and recycling. Circular supply chain The Indian cement industry is playing a key role in contributing towards a circular economy by enhancing the applications of renewable energy for electrical power generation. The renewable energy installed capacity (wind and solar) in cement plants has increased by more than 40% to 276 MW from 2010 to 2017. Of this, 42 MW is solar power, while off-site wind installations account for 234 MW. One cement company has undertaken the target of switching over to renewable energy for 100% of all electrical energy needs by 2030.

Progress in sustainability The Indian cement industry is considered one of the best performing industries across various industrial sectors in terms of energy consumption, quality control and assurance, and environmental sustainability, and is adaptive in terms of venturing into new technological options. Some of the recent major strides of the Indian cement industry include the reduction of the CO2 emission factor from 1.12 t of CO2/t of cement in 1996 to 0.670 t of CO2/t of cement in 2017, and enhanced blended cement production from 68% in 2010 to 73% of total cement production in 2017. Thermal Substitution Rate (TSR) refers to a partial replacement of conventional fuel by alternative fuels in terms of thermal energy requirement, and is calculated as a percentage of heat supplied by alternative fuel from the total heat requirement for pyro-processing in a cement plant. TSR has recently improved to 4% compared to a dismal 1% only 3 – 4 years back. From the TSR level of 4% in 2016 (0.6% in 2010), the Indian cement industry hopes to achieve 25% TSR by 2025 and 30% by 2030. Cement plants have adopted technologies to meet the new emission norms for particulate matter (PM) and NOx emissions. Plants have installed highly efficient bag filters, electrostatic precipitators (ESPs), and hybrid filters to control dust emissions. For NOx reduction, plants have installed secondary control measures like Selective Non-Catalytic Reduction (SNCR). Plants have also installed continuous emissions monitoring systems as per the guidelines of the Central Pollution Control Board. The Indian cement sector is considered an energy efficient sector, mainly due to the modern technology being implemented in the plants as well as efficient monitoring of the plants’ performances on a daily basis, focusing on energy savings and CO2 emissions reduction. India’s cement industry growth in next decade looks promising. 60

Recovery and recycling It has been established that different types of wastes/byproducts of other industries available worldwide can be utilised as alternative fuels and raw materials for cement production. Moreover, production of blended cements, composite cements and utilising performance improvers in cement also support a circular economy. Use of fly ash and granulated blast furnace slag (GBFS) in the production of blended cements i.e., Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC) is also beneficial for conservation of natural resources, lowering the clinker factor in cement and reducing CO2 emissions along with environmental sustainability. In the coming years, a circular economy will gain further momentum in the Indian cement industry by utilising gypsum generated from FGD in TPP, consumption of non-recyclable plastic waste, production of high-volume fly ash cement, utilising steel slag, the reduction of the clinker factor by alternative raw materials, and increasing TSR by the use of AFs. Usage of alternate fuels The opportunities for cement manufacturers to start burning alternative fuels are many, but it is a gradual process. Process knowledge is critical when starting up the use of alternative fuels because even the slightest change to one part of the process could create havoc. Many technological aides are available for plants from technology suppliers like Pfister, with an Alternative Fuels Starter Kit that comes with a complete package of equipment for materials handling, and dosing and burning, and is designed for using a wide range of alternative fuels like biomass and refuse-derived fuel (RDF). The enhancement of the thermal substitution rate will require adequate pre-processing infrastructure for RDF, both in terms of quality and quantity that will make it suitable for use in cement plants. One of the alternatives to improving the quality of locally generated RDF would be to World Cement September 2021

blend RDF (which typically achieves an energy value of 1500 kcal/kg) with a better form of RDF known as Solid Recovered Fuel (SRF), which is made from commercial and industrial waste. Current research towards CO2 emissions reduction Of late, significant research has been undertaken to develop low carbon cement alternatives like LC3, geopolymer binders, belite rich cements, and other novel cement formulations. Out of these options, LC3 and geopolymer concrete have significant potential for emissions reduction and are in the final stages of development in India. With the use of circular economy principles (like use of SCMs, and utilisation of construction and demolition waste through technologies like the ‘Smart Crusher’) and design optimisation techniques (like bubble deck/voided concrete slab systems, confined masonry, and use of timber) the demand for cement can be optimised in upcoming construction activities.

The way forward Reducing clinker content and alternate raw materials It is inevitable that the cement industry will make certain amendments in its current standards in order

to accommodate a higher amount of secondary cementitious materials (SCMs) and also opt for new standards in order to accommodate newer cement formulations. These changes in standards would help reduce the clinker component of cement, allowing not only for CO2 abatement but also for mineral conservation. Further reduction of the clinker factor and the use of alternative raw materials are key in reducing the environmental footprint of the cement industry. To put it into perspective, if it was possible to reduce the CO2 emissions from cement production by just one percentage point, it would be the equivalent of removing the fossil fuel used to provide 258 million households with electricity annually or replacing the use of fossil fuel with 19 000 wind turbines! Carbon capture and sequestration Carbon capture systems must target process emissions and combustion emissions. These systems have two categories: Post-combustion technologies aim to separate CO2 from exhaust gases and typically rely on chemical CO2 absorption (for example, by amines). Oxyfuel technologies react fuel with pure oxygen instead of air, generating a purer stream of CO2, and also can capture process CO2.

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STRONG AND

Riccardo Stoppa, GCP Applied Technologies, outlines the sustainable cement additive solutions that could help to protect the strength and performance of cement whilst curbing CO2 emissions.

he news is filled with promising reports of cement producers pursuing carbon neutral solutions, yet there is often little discussion of the myriad of challenges producers face in achieving this goal. Although there are exciting solutions available today to curb CO2 emissions, implementing these also requires multiple considerations to ensure they are maximising value for the producer.

Investors driving climate action Producers are under considerable pressure to produce cement in a more sustainable way. Members of the Institutional Investors Group on Climate Change and Climate Action 100+, a coalition of money managers with more than

US$33 trillion under management, is urging European construction-materials companies – including cement makers – to commit to reducing net CO2 emissions to zero by 2050. Investment group member and CEO of Ethos Foundation, Vincent Kaufmann, has noted that increasing numbers of investors are seeking to exclude highly carbon-intensive sectors from their portfolios to meet their decarbonisation plans. In an annual letter to CEOs, asset management company Blackrock Inc. announced that climate change has become a defining factor in companies’ long-term prospects, noting that over time, companies and countries that do not respond to stakeholders and address sustainability risks will encounter growing skepticism from the markets, and in turn, a higher cost of capital.

The world’s largest asset manager with approximately US$8.6 trillion in assets, Blackrock, has introduced numerous initiatives to place sustainability at the centre of its investment approach, including making sustainability integral to portfolio construction and risk management, exiting investments that present a high sustainability-related risk (such as thermal coal production), launching new investment products that screen fossil fuels, and strengthening its commitment to sustainability and transparency in its investment stewardship activities.

Typical clinker.

Sustainability and strength Despite these mounting pressures, it is not easy for the cement industry to make immediate adjustments. Being responsible for building materials that can last generations, producers are understandably wary of making changes unless there are assurances that they will preserve the integrity of their product. In other words, sustainable products must protect the strength and other desirable performance properties of cement. There are a number of solutions – both chemical and technical – that enable producers to do just that. There is no one-size-fits-all solution, however. Identifying the right choice for each plant involves a holistic approach that may encompass: f Conducting lab tests to identify custom chemistries for specific cement and concrete systems. f Enhancing the efficiency of the ball mill or vertical mill. f Ensuring best-in-class execution during field trials and regular operations. A cement plant customer in eastern Europe recently sought a grinding additive to facilitate a further 4% clinker replacement for their cement above the 3% reduction they were achieving with a traditional GCP Applied Technologies quality improver. GCP designed the new product, tested it on site, and produced cement of the same fineness. As a result, strength was increased in the order of 10% at all ages, in addition to achieving an increase in cement mill output of more than 4%. This enabled the plant to: f Reduce clinker by the desired 4% by increasing the limestone content. f Reduce operational costs by over 2%. f Lower CO2 emissions by a further 6% on top of the previous additive.

Capitalising on new market opportunities GCP’s manufacturing plant in Passirana, Italy.

Manufacturing line of GCP’s plant in Sorocaba, Brazil. 64

Accounting for 7% of global man-made CO2 emissions, cement is under the microscope when it comes to improving sustainability. Although there are goals such as the International Energy Agency’s Sustainable Development Scenario to drive incremental change, it is likely that market opportunities are what will spur the industry forward. The green cement market is estimated to grow to US$43.59 billion by 2027, providing a wealth of opportunities for producers who capitalise on these shifts. Fortunately, there are effective ways to help reduce embodied carbon in cement today through chemical cement additives. For instance, cement additive technologies first developed and introduced by GCP are currently enabling the cement industry to reduce approximately 65 million tpy of CO2. This represents roughly 3% of global cement CO2 emissions.1 World Cement September 2021

Accelerating the selection of sustainable additives Using multiple chemicals together can often offer sustainability advantages that represent more than the sum of their parts. However, with so many cement chemistries and variables to choose from, not to mention the individual constraints of each type of cement, it can be difficult for cement plants to readily predict the performance of multiple chemistries working together. Accurately predicting the anticipated strength and sustainability benefits involves a careful assessment of the existing business and technical needs and constraints. Having these discussions with an additive supplier can help to reliably increase the use of supplementary cementitious materials to reduce your carbon footprint and identify formulations that offer an improved net value.

Conclusion Reducing CO2 is a critical endeavour for cement plants. Choosing the right solutions involves a keen understanding of individual market conditions, the availability or lack thereof of locally-sourced raw materials, cement performance goals and metrics, and predictors of chemical additives. Working in partnership with cement plants to understand their

specific objectives and operational processes can help drive decisions that result in the trifecta of sustainability, strength, and savings.

References 1. One-year carbon emissions reduction, on the basis of 2019 volumes.

About the author Riccardo Stoppa is the Global Marketing Manager of the Cement Additives division at GCP Applied Technologies. He holds a Master’s degree in Industrial Chemistry from the University of Milan and an MBA from the SDA Bocconi School of Management. Riccardo has contributed to the development and launch of new technologies and products such as the CO2ST® reducer, Tavero® VM and innovative services such as the GCP DASH® real-time product selection application. GCP chemical additives enable cement and concrete customers to improve the strength and quality of their products. The company takes a holistic approach to tackling CO2 reduction, bringing together chemical research, experienced technical support, lab and field testing, advanced chemistry, and technology to ensure that the new chemistries they develop bring strength, savings, and sustainability to customers.

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INNOVATION IN CEMENT PRODUCTION

9 & 10 November An interactive, online conference focusing on the latest innovations in cement production. Including presentations from:

OPTING FOR Marco Rovetta, CTP Team, considers how cement producers could work towards achieving carbon neutrality, starting with the optimisation of existing plant equipment.

educing the cement industry’s carbon footprint involves two challenges – optimising the efficiency of equipment and recycling wasted energy which, in the cement industry, is concentrated in the excess heat from the manufacturing process. The primary actions to reduce industrial emissions and protect the environment began around 50 years ago, and technologies were developed that, seen with today’s eyes, have had a considerable impact on the balance of the environmental sustainability of the cement plant.

In addition to the reduction of the energy used in filters and gas cleaning through the optimisation of the equipment, a further step towards the optimisation of the environmental footprint of the cement industry is the reuse of the residual heat from the process in suitable WHR systems.

Environmental sensibility Starting in 1970, the constant improvement of environmental sensibility has brought about a wide range of pollution control systems. The importance of these systems is nowadays very relevant in cement production. Such importance is underlined by the fact that pollution control devices have reserved a considerable space in the BREF documentation, the official document used as a reference for preventing and/or minimising emissions and impacts on the environment in the EU. In the frame of the sustainability of industrial processes, today a new challenge for cement

producers lies in taking action to combat climate change, which is predominantly caused by greenhouse gas emissions (GHG) such as CO 2. Together with the adoption of new technologies applied to the production process, cement producers must also consider optimising energy usage in existing equipment. Unfortunately, most emissions control equipment is energy consuming to some degree and in some cases, could have a considerable impact on GHG emissions and production costs as well. Where possible, the installation of a Waste Heat Recovery system is a useful tool to recover residual heat from the process, and play an active role in the balance of the environmental footprint of the cement plant in terms of GHG generation.

Energy demand in a bag filter

In a bag filter, energy is used to face the pressure drop created by the flow of gas passing through equipment. The only means of controlling a filter’s pressure drop is the cleaning of the bags, adjusted according to a certain frequency. It is possible to distinguish a number of times that bags must be cleaned in order to maintain a certain filter’s pressure drop, of which Figure 1. The optimised operating condition is placed at the minimum value cleaning frequency of the total filter consumption curve. is inversely proportional. The cleaning system works using compressed air and it is possible to define the amount of energy used for cleaning in order to maintain a certain pressure drop. As mentioned, the pressure drop is the result of the gas passing through the filter and through this, some energy is Figure 2. Each component of the total amount of the energy used in a bag proportionally used filter is influenced by factors that need to be managed with a proper filter in the fan as well. design. 68

World Cement September 2021

Overall, the energy used for filtration is the sum of the amount spent in cleaning and fan energy. It is possible to find the optimised operating conditions placed at minimum value of the total filter consumption curves. Considering 100% of the filter consumption: 15% of filter energy consumption can be assigned to the production of the compressed air for cleaning, while the remaining 85% is used to let the gas pass through the filter. This portion includes resistance due to the filter housing (18%) and the residual pressure drop of the bag (8%). The biggest portion is caused by the dust cake at 59%. Each component of the total amount of energy used is influenced by factors that need to be managed with a proper filter design. The pressure drop of the filter cake depends on the amount of dust on the bag’s surface and its distribution and density affect the cake’s porosity. The residual pressure drop is related to the resistance of the bag felt without dust, provided that the cleaning system is capable of completely eliminating the dust cake. The residual pressure drop is related to the characteristics of the material used for the bag. The pressure drop due to the filter’s housing is dependent on the layout adopted. The amount of compressed air is a consequence of the sum of all the above factors and can control the cake pressure drop only. In order to help cement producers in the modernisation and decarbonisation of the plants, CTP Team focus on providing assistance for the optimisation of existing equipment and high skilled maintenance service.

The approach of the ‘OTP’ division OTP stands for ‘Optimisation Technology Performances’. The OTP division is specialised in the optimisation of bag filters and waste heat recovery systems, valuing reliability, quality and savings. The OTP technical approach is based upon deep process analysis and equipment validation, identification of critical points, and development of solutions to improve the existing equipment and solve plant problems to meet client expectations. CTP Team is also focused on the design of pollution control equipment, and the company is ready to do its part in tackling climate change challenges, optimising energy use in dust or pollutant abatement, without forgetting its main task.

Fast. Fair. Flexible.

Think bigger – with InterCem. From individual components to upgrades to complete plants, InterCem provides customized solutions for operators and investors of cement plants all over the world. InterCem is therefore also the right partner for you when it comes to planning, detailed engineering, project management of greenﬁeld projects and conversion/modernization of production plants. Contact us: The InterCem professionals will also ﬁnd the right solution for your requirements.

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The installation of a Waste Heat Recovery system can provide an effective contribution towards balancing the environmental footprint of the cement factory, as well as a concrete support in the energy transition from high to low carbon energy. The first action for cement plants to take is the optimisation of existing systems in terms of energy efficiency. Then, the installation of a WHR system allows for the production of clean energy without additional greenhouse gases.

installed in the Outão Cement factory, Portugal. The project will consist of several new developments to provide a highly customised solution to feed a double-loop system (thermal oil and organic), to recover waste heat and produce electricity from three different sources – the kiln preheater and clinker cooler of the existing 4000 tpd cement unit N°9 and a new solar field, that SECIL will install near to the production line.

Two renewables combined One step towards carbon neutrality An emission controls system combined with Waste Heat Recovery technology has the potential to keep emissions levels under control at the stack, increasing plant energy efficiency. The internal energy production by WHR can significantly reduce electrical costs. CTP recently partnered with CTN for the installation of two Waste Heat Recovery systems in Sonmez and Cimko Narli in Turkey. The Waste Heat Recovery boiler designed by CTP captures waste heat from the clinker cooler in Cimko Narli and from both clinker cooler and kiln preheater at Sonmez cement. The WHR based on the Organic Rankine Cycle produces clean energy – the internal power generation system operates without the use of water, a precious natural resource, and saves thousands of tons of equivalent CO2 emissions each year. Recently, CTP has been awarded a contract for new Waste Heat Recovery systems to be

For the Portuguese project, waste heat and solar energy will be combined to produce the electricity needed to partially cover the internal consumption of the Outão Cement factory. Reducing the environmental footprint of the cement industry is a challenging goal. The challenge is twofold – achieving carbon neutrality without burdening the overall process. A beneficial approach is to focus more on the total exploitation of all the resources potentially available from the process itself.

About the author Marco Rovetwta is a Mechanical Engineer with over 30 years of experience in the cement industry, especially in emissions control systems. He is a product innovation manager at the CTP Team, leading the continuous improvement of new products and looking for new technologies with the highest performance and best available techniques.

Figure 3. The Secil plant is located in Outao, Portugal; this WHR system is presently in the engineering phase: The AQC Boiler and PH Boiler are combined with a solar field. The WHR systems developed by CTP can easily integrate different heat sources and produce electricity. 70

World Cement September 2021

Jori Kaaresmaa, BMH Technology Oy, outlines the implementation of a waste-to-RDF production plant in Umm Al Quwain, United Arab Emirates.

WISE ABOUT WASTE he GCC countries1 hold huge potential for a circular economy. Their waste generation per capita is among the world’s highest and waste collection is organised professionally, yet currently the piles are mainly dumped in landfills. The calorific value of the region’s Municipal Solid Waste (MSW) is comparatively high, which makes it a perfect source for energy recovery. On top of these factors, the GCC countries have a significant cement industry sector that offers an almost bottomless yet ‘green’ way to not only recover the energy in waste but to also circulate the materials in it by means of co-processing.

Rising volumes of waste in the area are a direct result of rapid urbanisation, population growth and changes in consumption behaviour. The UAE have set a strategic objective for cutting down landfilling by at least 75%. The emirates of Umm Al Quwain (UAQ) and Ajman stand out as pioneers in implementing waste-to-fuel technology, as just an hour away from the vibrant city of Dubai, the country’s brand-new and first-of-a-kind RDF facility is in operation. It diverts the household waste of half a million residents away from landfills, sorts out valuable recyclables and refines the combustible substances into sustainable fuel, which is then used to power the nearby cement industry.

Background Before any project can take off, all the puzzle pieces must be identified and brought together. This applies particularly well to politically driven and environmentally significant projects such as a venture for diverting MSW away from landfills. In addition to well-managed waste collection and logistics, it requires investors to provide funds, a technology supplier with a proven solution, off-takers to agree to use the end-product, and finally someone to put it all together. Even with a complete set of puzzle pieces, nothing will happen without political will that is manifested by tangible actions. In the northern Emirates of UAE, the last piece was put into place in 2019 when the country’s federal government launched a new Ministerial decree for cement companies nearby to use MSW-based RDF (Refuse Derived Fuel) as substitute fuel in their cement production processes. This was the deciding moment for the implementation of the MSW-to-RDF plant that is now operational. The project was supported by the Ministry of Climate Change and Environment (MOCCAE) and the newly built facility in UAQ is owned and operated by Emirates RDF.

The received unsorted municipal solid waste (MSW) can contain virtually anything from food and furniture to bricks and batteries.

The entire system was delivered turn-key by BMH Technology Oy, a Finnish company specialising in demanding waste-to-fuel applications and solid fuel handling systems. 72

In order to make co-processing an attractive option for any cement company, the alternative fuel (AF) must fulfil certain criteria in terms of calorific value, moisture and chlorine content as well as quality consistency and secured fuel availability. On the other hand, to make it attractive for a municipality or an Emirate, the total concept will contribute to the strategic objective of landfill diversion rate, be technically proven, and naturally economically feasible. All these requirements are materialised in the newly established concept in UAQ.

Process overview At the core of the concept is the TYRANNOSAURUS® waste refining process that recovers valuable materials for recycling, removes non-combustibles and refines the remaining MSW into high-quality RDF. The system was delivered by BMH Technology, a Finnish company that is a specialised and experienced technology supplier for different solid waste processing systems. BMH Technology was selected to develop and supply the fuel production process due to the company’s track record and reputation as a reliable partner, and its deep understanding of the requirements of the cement process. To reach the targets mentioned above, MOCCAE together with Ajman and Umm Al Quwain Municipalities set high requirements for the performance of the plant. The system is designed to process 1000 t of unsorted MSW per day (or over 350 000 tpy), converting more than 80% of it into RDF that fulfils the requirements of the cement industry. In practice, this means a daily production of 800 t of fuel which can replace some 500 t of coal used by the cement plants. The particle size of this fuel must be constant but also small enough to allow rapid and complete combustion in the calciner, and to allow as many cement plants as possible to use this AF without major modifications. The process to produce the specified alternative fuel contains two identical lines. Both lines consist of four main parts: 1) MSW receiving, 2) shredding, 3) sorting, and 4) storing – all installed in one roofed building with half walls. The building has dedicated and properly ventilated and/or air-conditioned rooms for electrical cabinets, hydraulic power packs and spare parts. Operators monitor and manage the plant from the control room, but it is also possible to do the same at the local control desks beside the machines. Due to the highly automated system, only one operator is needed to control the line. The rest of the staff have their dedicated roles in loading the MSW into the process, managing the side streams and RDF, as well as carrying out the maintenance tasks according to a preventive maintenance programme. The MSW reaches the plant by trucks. Before delivery to the receiving hall, each batch is measured at the weigh scale. In the receiving hall, material is first tipped on the floor for visual checks World Cement September 2021

and then moved either directly to the process or to the raw waste buffer storage. At this point, the operator has the chance to remove some items, such as gas bottles, car batteries, etc. that are sometimes found in the waste and that may disturb the process or contaminate the RDF. Loading MSW into the process is carried out with a front loader that empties its bucket onto the TYRANNOSAURUS feeder which then doses the waste into the process.

Process description

from damage by unshreddable items accumulates and the yearly availability stays high, resulting in higher annual capacity. After exiting the shredder, the material is transported through a two-stage metal separation station. The first stage removes magnetic metals from the waste stream with a strong electrical magnet. After that, the non-ferrous metals are separated efficiently with an eddy current separator. The separation efficiency and purity of the ferrous and non-ferrous metals is very high due to the small particle size of the material stream. The recovered metals are sold to be recycled and refined. To reduce the content of sand, soil, dust, glass splinter and other small inert materials in RDF, a fines screen is applied. The separation rate of this unit can be adjusted from the control room based on the fines content in MSW, and the ash limit of the RDF specification. Rejected fine materials are mainly free of organic content and they are often used as inert filling material.

The actual processing of unsorted MSW starts by shredding everything to a predefined particle size in one single shredding stage. This is done by TYRANNOSAURUS 9905 shredders, each unit reaching the peak throughput capacity of 50 tph when producing an average material size of approx. 40 – 50 mm. The produced particle size is optimised primarily to meet the requirements of cement companies. However, a constant and even flow of small particles also contributes to high-accuracy sorting in the next steps of the process. The feeder integrated into the shredder provides a fully automated system, maximising the annual capacity of the production plant by maintaining high availability even with most challenging waste materials. The shredder is constantly communicating with the feeder and the plant control system to ensure an optimum feeding of material into the shredder. Feeding is an important factor for the capacity, as too little feeding only allows the machine to utilise a portion of the full capacity. On the other hand, too much feeding can result in blockages. The material bed height in the shredder is measured and this information is used to optimise the feed rate. The intelligent pusher inside the shredder controls The ready RDF, a light fluff that is free from the capacity between the feeder cycles, maintaining metals, sand, stones and glass, is stored a constant load on the rotor and maximising capacity. in bunkers and sold to the nearby cement The ZeroGap® feature ensures that the capacity industry. of the shredder remains high even with worn knives. The distance of the rotor knives and the counter knives is semi-automatically adjusted during daily inspection. Due to this feature, the thinnest materials, such as plastic foils, are shredded. The sharp cutting profile achieved by the ZeroGap also minimises the power consumption at this otherwise very power intensive phase of the process. The Massive Impact Protection System (MIPS®) protects the shredder from damage caused by unshreddable items. Once an impact is detected, the shredder automatically moves the unwanted particles into a separate reject container and resumes normal operation without any user The TYRANNOSAURUS plant is designed to process 1000 t of input. This feature ensures that no unsorted MSW per day, which amounts to more than 350 000 t unexpected maintenance downtime annually. September 2021 World Cement

Next the material enters the air classifier. It divides the material into heavy fraction, middle fraction and light fraction. The separation is based on the aerodynamic properties of the particles when they enter a strong airstream. The lighter particles are carried further away compared to the heavier particles. The air classifier can be adjusted according to customer needs by damping the fan, or reducing its speed of rotation, or by adjusting the position of a dividing roller and the collecting conveyor inside the air classifier. In other words, the customer can adjust the quality of the fuel as needed. The heavy fraction rejects from the air classifier are high-density particles, such as stones, soil, glass, pieces of brick, and residual metals. After the sorting process, the RDF that is now free from metals, sand, stones and glass, is discharged

into the storage part of the building. This section contains six large bunkers that the operator can fill by selecting the desired bunker from the control system. This flexible storage system also allows storage of different types of RDF, if required. For example, there may be different RDF specifications by different cement plants. These can be produced by changing the settings of the production line, and then the produced RDF can be stored in the dedicated bunker. Or, sometimes there may be a need to process batches of some special wastes; the flexible RDF production system makes this possible, and again the produced RDF can be stored separately by the storage system. Finally, front loaders move the desired material from the selected bunker to the truck which takes it to be delivered to a nearby cement plant.

The results and discussion

The TYRANNOSAURUS 9905 shredder can reach a peak throughput capacity of 50 tph when producing an average material size of approximately 40 – 50 mm.

The positive impact that this project has had on the area is undeniable. Using RDF as an alternative energy source in the cement industry has an overall benefit on fuel and raw material costs, not to mention the environmental benefits. Instead of dumping 1000 t of waste to landfill daily, 850 t are now recovered as recyclable metals and environmentally friendly sustainable fuel. The amount of coal that can now be replaced with the produced amount of RDF would have generated 1600 t of fossil CO2 emissions daily. On top of this, the RDF is locally produced, which further reduces emissions and enhances local business by creating employment. The future of the region’s sustainable waste management and energy production is starting to take shape. The Arabian Gulf has the potential to multiply the benefits of this single project by adopting the presented concept on a wider scale.

About the author Jori Kaaresmaa is a Senior Process Specialist at BMH Technology Oy, representing the company’s Business Development and Strategic Sales department. He has more than 20 years of work experience in both TYRANNOSAURUS plants and in the cement industry and is mostly involved in the pre-sales phase researching possible technical solutions for each customer case. The RDF facility is strategically located in a logistic intersection of the Northern Emirates, close to both the waste producers and RDF users. 74

Reference 1. Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates. World Cement September 2021

MODERN MAINTENANCE AND MONITORING The New York Blower Company details an innovative strategy for equipment management and maintenance that leverages robust fan design in combination with advanced remote monitoring systems and IIoT technologies.

ndustrial fans sustain many critical functions and sensitive processes throughout a cement plant. There are induced draft (ID) fans that supply air for fuel combustion, exhaust fans that remove gas and dust particulates, and coal mill fans that provide airflow to burn coal and eliminate gases, to name a few. These heavy-duty industrial fans are exposed to some of the most challenging operating conditions, including high temperatures, vibration, rapidly changing process conditions, heavy dust and debris accumulation, and more. Furthermore, over the life of the equipment, fan efficiency typically degrades from its original operating conditions.

This requires equipment motors to work harder, increasing energy consumption and power costs, and posing safety hazards if motors are running outside of the safe range. Keeping fans within a cement plant running smoothly, safely, and efficiently is critical to avoiding costly unplanned downtime and lost production time. However, continued exposure to hot and dirty operating conditions will inevitably lead to fan wear over time, with continual maintenance costs if not provided properly.

Common types of fans and key challenges for cement plants Motor vibration sensors attached to the fan measure vibration velocity, as well as monitor temperature and vibration levels.

The following are several common fan applications within cement plants, as well as the key challenges for these fans. Raw material conveying Raw mill fans move raw meal through production. For these fans, the primary challenge is to avoid excessive debris build-up due to sticky dust. When these dust particles accumulate, especially in uneven patterns on the fan impeller, the fan can become imbalanced, and the system may be at risk of total failure.

The shaft collar pressure and air temperature monitors transmit real time data with the ability to enable automatic calibration.

An Accutron flow sensor in the fan duct helps monitor, control, and diagnose potential problems with air flow. 76

Preheater and kiln fans At the beginning of the cement production process, the raw material is dried using hot air from a kiln exhaust fan. The fans draw the air – which can reach 450˚C (842˚F) – from the kiln and into the raw mill area to preheat the material. After preheating, the material moves into the kiln, where process temperatures can be as high as 1093˚C (2000˚F). Induced draft (ID) fans supply air for fuel combustion and exhaust fans expel gas and dust particles. The primary challenges for preheater and kiln fans are the high temperatures, heavy dust loads, and the mixture of gases to which fan elements are exposed throughout the process. Clinker cooler fans After heating in the kiln, the raw meal becomes clinker, a solid and highly abrasive intermediary product of the cement production process that presents as particles of varied in size and shape. Fans involved in the clinker cooling process must be able to withstand the resulting abrasion World Cement September 2021

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and wear from exposure to these particles. Cooling fans must also be designed with power requirements in mind, as improperly designed cooler fans can lead to high power consumption and excessive energy costs.

remote monitoring and IIoT technologies that can be used to optimise fan performance, identify the signs of wear early so that they can be resolved quickly, and ultimately save significant costs over the life of the fan.

Coal mill fans Coal mill fans create airflow for coal burning and gas elimination. Similar to other fans in the cement production process, coal mill fans are frequently exposed to high temperatures and dust-loaded air.

What is remote monitoring? Remote monitoring gives users insights into fan performance and equipment health in real time. It works by installing sensors at key points on the equipment to identify critical changes in performance. For example, mechanical sensors mounted to the motor shaft can measure vibrations, comparing real time vibration frequency to an established baseline. As fan bearings wear, vibration frequency increases, which is an early indicator of a mechanical problem. Particle sensors can also be used to monitor the volume of dirt and dust in the airstream. Simultaneously, current and voltage sensors continuously monitor power inputs in order to optimise energy consumption and quickly identify when fan behaviour indicates an inefficiency. Remote monitoring sensors can quickly identify acute conditions that require immediate actions and monitor subtle performance changes that predict future failures so they can be prevented with proactive maintenance. This is also called predictive maintenance. Ultimately, this means that by continuously monitoring air blowing equipment, cement plants can respond to critical conditions in real time and effectively plan maintenance schedules to resolve problems before they escalate to catastrophic failure and downtime – all while optimising overall fan performance and efficiency.

Remote monitoring advantages There are many design approaches that can help mitigate wear, increase the overall life of the fan, and extend the time between repairs. One solution is to choose wear-resistant materials designed to withstand the rigours of the specific application, and to apply liners or overlays that protect the base material from corrosion and other forms of wear. In addition, fan manufacturers should design fans with the appropriate geometry to reduce uneven particulate build-up on the fan’s impellers. While these tactics remain critical to high performance and high efficiency fan design, they are ultimately preventative measures that merely slow down wear. Ruggedness alone is insufficient. Remote monitoring takes prevention a step further and can actually help predict and prevent the ultimate consequence of equipment failure – unplanned downtime. To keep cement plants running as smoothly and efficiently as possible, effective fan design should be leveraged in combination with

ABB Smart Sensors monitoring system collects data on the collar temperature and pressure on fans. 78

Why remote monitoring? Over the past decade, remote condition monitoring has quickly become a popular solution to effectively manage and maintain industrial equipment. The benefits of the technology have become rapidly apparent across industries. The reasoning is because remote condition monitoring and predictive maintenance give users accurate data and visibility into the performance of their equipment at their fingertips: A powerful capability that helps users World Cement September 2021

make real time data-driven decisions that save costs and drive efficiency throughout the entire plant. While remote monitoring might sound like an expensive upgrade to existing installations or as an addition to an initial fan deployment, it is actually only a minimal additional upfront cost that ultimately pays for itself by reducing the total cost of ownership (TCO) over the life of the equipment. The following are a few practical examples of how remote condition monitoring is being used in cement plant equipment and the value it can provide for operations.

Reduce costly unplanned downtime Downtime is expensive – especially when it is unexpected. The costs of sudden, unplanned equipment breakdown can soar to millions of dollars in lost productivity if work is stalled while staff scramble to identify and fix the problem. Remote vibration and temperature monitoring can help prevent this worst-case scenario by indicating problems early on, and by helping to quickly pinpoint and diagnose critical conditions when they do happen. How does this work? Essentially, all industrial fans operate at a tolerable baseline level of vibration and temperature fluctuation. Some variation is normal, and isolated spikes often are not a cause for alarm. However, sustained changes to the baseline over time can be the first indication of a problem. For example, uneven dust loads on the fan impeller will gradually increase vibration, eventually resulting in premature fan wear or unexpected failure. With remote monitoring, users are alerted to the upward trend in vibration and/or temperature so that it can be investigated and resolved before it results in major damage. To do this, vibration and temperature sensors are installed at the fan shaft and bearings to observe and interpret changes that could affect performance. If an alarm threshold is met (i.e., vibration has exceeded acceptable limits for a period of time), a text message can be sent to an operator’s phone to let them know the equipment needs to be evaluated soon. Personnel can then quickly diagnose and resolve the issue before it escalates into a bigger problem. Data can also be fed into dashboards at a command centre to map trends over time, visualise performance insights, and more.

Leverage the power of predictive maintenance Traditional preventative maintenance plans rely on regular, scheduled maintenance to ensure September 2021 World Cement

smooth equipment operation. In comparison, predictive maintenance uses real time data from the equipment to reliably predict and prevent major problems that can lead to costly unplanned downtime. Predictive maintenance is also significantly more accurate in capturing data compared to manual data collection methods. This is important because more accurate data enables better decisions. Remote monitoring also allows users to track trends over time to continuously improve the efficiency of their operations. Data can be used to measure and improve overall equipment effectiveness (OEE), which is a percentage value that represents the equipment’s total availability, performance, and production quality. Overall, these capabilities empower users to be proactive rather than reactive in how they manage and take care of their equipment. Ultimately, by combining these technologies with robust fan design, users can achieve better efficiency, with shutdowns only for planned maintenance.

Optimising power consumption One last but important consideration for installing remote monitoring systems is how they can help save significant power consumption costs, one of the largest expenses associated with the operation of air blowing equipment. Remote airflow and pressure monitoring technologies provide visibility into the fan’s efficiency metrics in real time, allowing users to quickly identify when a fan is running inefficiently and using more power than normal or necessary. Personnel can then be alerted to further investigate why the fan is running inefficiently so they can resolve the problem. Because power is such a big expense, optimising fan power consumption can result in considerable long-term savings and significantly improve margins.

Conclusion For industrial fans installed in cement plants, ‘built-to-last’ is no longer enough to support critical functions throughout the plant. To be competitive in today’s cement industry, plants must approach fan equipment with a modern strategy that combines robust design with the latest remote monitoring and predictive maintenance technologies. This not only improves the reliability and efficiency of equipment, but also helps plants maximise production and reduce the total cost of ownership (TCO) by optimising ongoing maintenance and power costs. A knowledgeable and experienced air blowing equipment manufacturer can help customise the most reliable, cost-effective solution possible for any application. 79

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World Cement September Issue 2021

Articles inside

Opting For Optimisation

Wise About Waste

Modern Maintenance And Monitoring

India: Striving For Sustainability

Cement In Central Asia

Greener Times Call For Greener Measures

The Benefi ts Of A Better Brush

News

California Crushing

Ready For Rapid Recovery & Repair

The Natural Choice

Getting The Most Out Of Maintenance