SHAPA Supplement July 2015

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Solids Handling & Processing Supplement

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July 2015

A STEADY COURSE IN A SEA OF CHANGE

By Gus Bishop – Solids Handling & Processing Association It goes without saying that this year - as yet only half spent - has seen many changes.

Politically we can hope for a few years of stability on the home front, but a large question mark hovers over continuing EU membership.The uncertainty surrounding the General Election may have faded into the past, but issues raised, demands tabled and difficult promises have all had their effect on trading conditions. The strength of the pound both in the Eurozone and across the Atlantic provides challenges for exporters that will not go away. The flipside of this is cheaper imports which add a further twist to the business plans of UK based manufacturers and suppliers. In order to eliminate the UK trade deficit and start to reduce national debt, we cannot rely solely upon the City and financial markets. All product manufacturing and indeed farming and other food and drink production must raise the bar of efficiency and productivity. It may be somewhat trite to say that we should manufacture goods and provide services that people actually want to buy.. However, achieving this noble aim requires innovation, research and development to be practised remorselessly month by month, with a close ear to changing and evolving needs across markets at home and worldwide.

AWARDING ENTERPRISE AND ACHIEVEMENT

So, what of the year so far? SHAPA and its member companies have been very much in tune with the industrial (and political) zeitgeist. In particular the need to encourage and promote innovation, enthusiasm and excellence has been at the heart of the Association’s planning and activities. The recently introduced SHAPA Industry Awards have been very well received and will, we hope, become part of the annual body of events. Why not trumpet success when it has been hard won by teams of dedicated people playing upon frequently decidedly wobbly playing fields?

The Innovation Award , won this year by Process Link for their intriguing FIBC discharger, was closely contested, with AJAX and VEGA in hot pursuit. It demonstrated that what is often regarded as a steadily evolving industry is nevertheless peppered with innovative, game changing, new products. This sort of consistent effort is vital to British industry in general and for the future efficiency of the solids handling and processing industries.

We need a successful exporting base. Right now this is easier said than done but is especially required to counterbalance the efforts of those promoting imported goods - a balance flow would be ideal.

Export earnings demonstrate a level of persistence, foresight and achievement in a hugely competitive arena and SHAPA realises the importance of winning export orders with the presentation of the Export Award. Many member companies put a great deal of effort into this endeavour and the quality of the entries reflected this. Russell Finex were finally judged the winners in this category.

With 75% of their sales now overseas, utilising local language tools and local representatives and also having increased their strength by 60 employees in the last three years, they demonstrated the spirit that impressed the selection panel.

The final award was aimed at consistent progress on all fronts, building upon accumulated success to AL wi with ith optional BTD BT TD Ball Type Diverter deliver continuously to a high standard - the Victor ventbox ntbox box and dropoutbox dropoutb Ludorum of awards. SHAPA Company of the Year was awarded to Spiroflow - again a very close decision because of the commitment of so many of the Association’s member companies. Spiroflow When handling abrasive materials, the use of abrasion resistant rotary and impressed with their new technology centre, solid diverter valves for replacement or re-adjustment regular increases in sales volume, their commitment to training and steady structural expansion.The of worn parts, the and thus the . quality of entries in all three categories deserve high Also the valves have a more , praise and the whole SHAPA team congratulate all who participated. making preventative maintenance schedules easier to establish.

reduces the downtime refurbishment costs cost of ownership predictable and reliable performance

PEOPLE

Not only have companies been recognised. At the recent General Meeting, outgoing chairman Peter Guttridge presented Mike Slack of H+H Services with a Lifetime Achievement Award. Mike has worked tirelessly for SHAPA, steering the Marketing Committee for many years. All this work has been voluntary, fitted in between a very busy business life and we thank Mike heartily for his efforts.

Peter Guttridge himself has served the Association as a particularly dynamic Chairman of the General Council for the past two years, plus several years of service to the council previously. He was presented with a Silver Salver by new chairman Mike Bradley.

Professor Mike Bradley of the Wolfson Centre in Greenwich has now taken the reins. Continued...

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Wolfson are well known for their academic excellence and work particularly on the flow properties of solids in bulk, assisting many process engineers with handling and storage issues. It is well known that solids in bulk are far less predictable than pure solids, liquids or even gases, with properties that change according to how they are being handled or processed. One of SHAPA’s long standing aims has been to turn what was once regarded as a “black art” into a well researched science, with reliable, accessible data for all. Huge cost savings are available to those who

really know their materials - manufacturers, vendors, processors and end users can all benefit. So, as ever, SHAPA remains in good hands as we look ahead.

SHAPA lives and indeed thrives on the valuable voluntary input of its members.

Only the General Secretary is on the staff and in this role Ian Birkinshaw is doing sterling work in coordinating the wide ranging activities of the Association.

His long management, engineering and contracting experience in the past with York based member company Portasilo is being put to profitable use with SHAPA. Long may he continue this work!

The General Council, the steering group for the Association, has some new members, in addition to Mike Bradley as new Chairman; Steve Brown of Thameside Sensors as vice Chairman, together with new council members Declan Barry of ATEX Explosion Hazards and John Harrison of Procon. We are delighted to welcome all of them and look forward to further expanded insight and progress for the benefit of all members.

EVENTS

Digital marketing, a rapidly evolving and nowadays vital sales tool was once again promoted to members with the 7th annual Digital Workshop held earlier in the year. Providing comprehensive bang-up-to-date data and guidance, this is an event not to be missed - a firm favourite now on the SHAPA calendar.

Equally important is taking care of succession, enthusing emerging engineering managers working up through the ranks. With this in mind there will be another Engineering the Future event on October 15th at the National Heritage Centre - further details to be available shortly.

Many other focused events and ideas are at the discussion and planning stages to provide information, insights and initiatives to drive productivity throughout our sector. If you are not already a member, or are not making use of members’ facilities via the website Product Finder, we are sure that the contents of the following pages will provide compelling reasons to consider the Association and its members. Don’t forget to visit our website at www.shapa.co.uk.

ENJOY THE FOLLOWING PAGES.

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NARROW SUCCESS FOR SOLIDS RADAR LEVEL SENSOR UNIQUE SOLUTION PROVIDED WITH CONTACTLESS RADAR LEVEL SENSOR A non contact bulk solids radar sensor with 120m range? You think this would be featuring an application with measurement over many tens of metres.

However, one of the first successful applications for the new VEGAPULS 69 - the latest generation of bulk solids level sensors - demonstrates its great versatility. At a UK Waste processing facility a device is now installed and working in a difficult application over a very short range of just over 2 metres down a very tall nozzle, through a valve and into a confined vessel.

Figure 1: VEGAPULS 69 Radar on waste collector, installed high above the valve and barrel cabinet The application is in a high temperature ash outlet from a gasification process where, via a screw conveyor, the hot waste, at around 400°C and under a vacuum, is deposited into a metal barrel container inside sealed cabinet. The barrel level needs to be monitored for changeover - when this is required, the process vacuum is protected by a valve, which closes while the cabinet is door is open. This valve is also the portal that the level measurement must be made through and, of course the sensor has to be contactless to measure through it. Weighing was not an option, as the ash density varies too much, and the very high temperatures would cause issues for most other technologies considered. Other measurement challenges include; very high levels of dust and fumes, vacuum, changing particle size and density, no ‘air purging or cooling’ allowed due to the combustion method, as well as the falling waste stream as it drops through the same valve into the barrel.

The original radar level sensors used have worked well with no signal loss, but ash build up and sublimation of vapours, in the narrow confines of the mounting tube and around the valve aperture, have caused periodic problems for the operators over the long term. This was because the radar sensors, although carefully installed and set up with ‘false signal suppression’, did not have a narrow enough beam angle to avoid the build up, which was causing intermittent high/full barrel levels. Cleaning the internal structures cured these issues, but it was not an easy task, was time consuming and it interrupted the process.

A new VEGAPULS 69 radar is now installed in its place. It has much narrower focussing (3.5°), the device therefore has no interfering echoes from the nozzle or the 6”/150mm diameter slide valve, which is approximately 0.8m away from the sensor. The set up was quick and simple, virtually no ‘false signal suppression’ required and it is able to measure directly right down into the barrel, with no loss of signal from the prevailing process conditions.

This increased reliability means that the process is now more productive and change-overs only called for when needed. Because the measurements are more accurate and the high levels can be more confidently anticipated, the operators can coordinate more efficient change over sequences, saving time and increasing safety. While this new radar has shown excellent near range performance – remember it has a range of up to 120m, enough for the largest of silos, and it also has a fast responsive output, which means it can be used on conveyors and object monitoring applications too.

Figure 2: Waste Ash in the barrel This new radar technology takes yet another big step closer to a universal solution for solids level measurement. ATEX dust and Gas certified with Profibus and FF outputs are among the available options.

Contact VEGA for a demonstration with a battery powered device or to arrange a trial in your application VEGA Controls Ltd Burgess Hill, West Sussex.

Tel: +44 1444 870055 Fax: +44 1444 870080 E-mail: info.uk@vega.com Web: www.vega.com/uk

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

TRANSPAC: THE CARBON DOSING SOLUTION

The TransPAC is a fully containerised carbon dosing system, utilising a Transvac Ejector.

With no need for building or ground works, TransPAC provides a safe and secure home for your dosing solution.

TransPAC provides once-through inline dosing, meaning no batch mixing tanks to contend with. The fully programmable control panel provides accurate and efficient dosing.

TransPAC has no ‘wet mixing’ moving parts, providing unrivalled reliability and it even flushes the lines clean on shut-down. A bulk bag or silo feed option is available to meet your site needs.

TransPAC offers outstanding value as it can be taken from site to site as required which is ideal for treating seasonal issues such as algae bloom, taste & odour or pesticide contamination, including successful removal of Metaldehyde. Metaldehyde is notoriously difficult to remove; TransPAC has proven to be successful in removing the pesticide from potable water.

For more information contact Transvac Systems Ltd, Alfreton, Derbys.

Tel: 01773 831100 E-mail: sales@transvac.co.uk Web: www.transvac.co.uk or Web: www.carbondosing.com

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PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

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J. R. BOONE’S MIXER MAKES SHORT WORK OF STABILISING WAC FAILING MATERIALS FOR AUGEAN PLC

J. R. Boone Mixers have supplied a large continuous mixer to Augean PLC to process industrial waste prior to land filling at their Kings Cliffe site near Peterborough, The Horizontal paddle mixer is capable of processing up to 720 Cubic metres of material per eight hour shift, mixing and consolidating the waste to form a stable material, allowing WAC non-complaint materials to become safe for landfill.

J. R. Boone already have a successful track record with Augean, having previously supplied a 6-tonne batch paddle mixer to the company for a similar application. Although Augean did compare J.R. Boone mixers with others, this successful history along with a competitive quote, led to J.R. Boone Ltd being awarded the contract.

The use is a heavy duty application and the materials being processed are, of course highly abrasive, so the contra-flow mixer paddles mounted within the U shaped mixing chamber are made from wear resistant ‘Abro Steel’ Based on their experiences in the previous installation, Augean requested a couple of key additions, particularly by including ‘bomb doors’ to facilitate full discharge of the mixer for cleaning, adding an extra degree of user friendly application to the process.

Commenting on the project, Simon Moyes the site manager at King Cliffe, said “J.R. Boone already understood the principles of our process so we were able to make the project run very smoothly.

Installation was seamless and we are delighted with the way the J.R. Boone mixer has operated”.

JR BOONE BACKGROUND INFORMATION John R Boone Mixers and Mixing Systems are used worldwide in the production of powders, granules, pastes and liquids. Reliable, versatile and economical in operation, Boone mixers and blenders feature in applications as diverse as welding flux, soap powders and heart tablets.

Its projects team draws on decades of mixing data and experience to create the ideal solution for any application. The proven range of mixing, de-agglomeration and conveying equipment includes innovations such as its high-shear Horizontal Delta Blade Mixer, Horizontal Helical Blade (Ribbon) Mixers, Horizontal Paddle Blade Mixers and low-shear Rotary Drum Blenders. The company also provides long-term support through its team of skilled maintenance engineers and its spare parts service.

For more information contact Chris Boone, John R. Boone Ltd, Congleton, Cheshire.

Tel: 01260 272 894 Fax: 01260 281 128 E-Mail: sales@jrboone.com / Web: www.jrboone.com

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PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

FAST, HIGH CAPACITY PRECISION MIXING The new Bella XN double shafted Fluidized Zone Mixer by Dynamic Air includes access doors which not only increase accessibility but also make it much easier to clean when necessary. The Bella mixer achieves fast, high capacity, low shear, precision mixing of either dry bulk solids or liquids with solids. Regardless of particle size, shape or density, materials are mixed with a fast, efficient, and gentle action - typical mixing times are 60 seconds or less. A weightless zone created by low-speed counter rotating shafts generates very low friction without shear. This makes it ideal for fragile products that cannot tolerate rough handling. Even flakes or spray-dried bodies remain intact. The Bella XN mixer includes twin bomb-bay door openings for fast, efficient discharging and to minimize segregation during discharge. The Bella mixer is available in stainless steel for sanitary applications. Custom sizes, finishes and materials of construction are available upon request.

For more information contact Dynamic Air Ltd. Milton Keynes Tel: +44-1908-568155 E-mail: sales@dynamicair.co.uk Web: www.dynamicair.com

FROM STAND-ALONE BULK HANDLING EQUIPMENT TO INTEGRATED SYSTEMS

Individual bulk handling equipment from Flexicon includes: Flexible Screw Conveyors, Tubular Cable Conveyors, Pneumatic Conveying Systems, Bulk Bag Dischargers, Bulk Bag Conditioners, Bulk Bag Fillers, Bag Dump Stations, Drum/ Box/Container Tippers, and Weigh Batching/Blending Systems. Each of these product groups encompasses a broad range of models that can be custom engineered for specialized applications, and integrated with new or existing upstream and downstream processes and storage vessels.

For large-scale bulk handling projects, Flexicon’s separate Project Engineering Division provides dedicated Project Managers and engineering teams on four continents to handle your project from concept to completion. Working with your engineering firm or directly with your team, Flexicon adheres strictly to your unique standards, documentation requirements and timelines through a single point-of-contact, eliminating the risk of coordinating multiple suppliers.

All equipment is available to food, dairy, pharmaceutical and industrial standards and conforms to ATEX, UL, CSA, CE and other electrical standards.

For more information contact Flexicon Europe Ltd Tel:+44 (0)1227 374710 E-mail: sales@flexicon.co.uk Web; www.flexicon.co.uk

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PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

THE DESIGN, INSTALLATION, CALIBRATION & ONGOING MAINTENANCE OF PROCESS WEIGHING SYSTEMS Process weighing plays a vital role across a broad spectrum of industries and, with continued pressure on manufacturing performance and profitability, there is an increased focus on reliability, performance and accuracy. Weightron Bilanciai’s Sales Director Emlyn Roberts reviews key issues relating to the design, installation, calibration and ongoing maintenance of process weighing systems. An overview of legislative requirements is also discussed.

Process weighing can be broadly subdivided into the following categories, each with their own specific requirements:

- Basic level control - Stock/inventory control - Batching and blending - Recipe formulation - Loss in weight - Bulk discharge weighing - Filling and decanting

Design parameters have to take into account a wide range of operational, environmental and legislative issues, all of which can have an impact on overall cost and performance. Installations can be divided into new and retrofit.

Although the same fundamental design rules apply to both, retrofit weighing systems may present different challenges, especially relating to structural integrity.

MEASURING CHAIN

Process weighing systems typically consist of primary measuring sensors (usually strain gauge load cells), appropriate mounting hardware and instrumentation.

INSTRUMENTATION, SOFTWARE & DATA MANAGEMENT

Although many of the fundamental mechanical principles of process weighing have not seen quantum changes over the past three decades, advances in electronics, software and, of course, the web have had a major impact on the versatility of process weighing systems. Weighing systems used to operate in ‘splendid isolation’. The collection and transfer of critical weight data from the factory floor was carried out manually and integration with management software systems was virtually non-existent. Effective weight data management now plays a growing role in many applications, both locally and remotely. To achieve this there is now a wide range of dedicated instrumentation, software systems and interfaces.

These bring real time bi-directional communication between the factory floor and essential management systems (ERP, Sage, Navision etc). Versatile colour touch screen weighing terminals that can be readily userdefined have brought significant advantages and removed the need for local PCs in many applications.

WEIGHING SYSTEM PERFORMANCE

Accuracy is an important factor in process weighing systems. Unfortunately the term is often misunderstood, mixed up or confused with other measurement parameters, especially repeatability and resolution. Although theoretical accuracy levels can be calculated for weighing systems, these are modified by a number of external factors and it is therefore more important to understand what can be realistically achieved in practice within the everyday working environment. In parallel, accuracy levels are often mixed up with error (or more correctly ‘uncertainty of measurement’). In common parlance it is not uncommon

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

for levels of accuracy to be quoted, for example, as 1 part in 1000 or 0.1%.

What is really meant is that the system has an ‘uncertainty of measurement’ or error of 0.1% and in fact the accuracy is 99.9%.

ACCURACY VERSUS REPEATABILITY AND RESOLUTION

The definitions (courtesy of Institute of Measurement and Control document WGC0496) are as follows: Accuracy: the closeness of agreement between the result of a load measurement and the true value of the load.

Repeatability: the measure of agreement between the results of successive measurements of a weighing system output for repeated applications of a given load.

Resolution: the smallest change in weighing system output that can be meaningfully distinguished.

The time frame over which the weighing process takes place has a major impact on overall weighing performance. Three key factors need to be taken into account:

- The overall long term zero stability of the weighing system - The linearity of the weighing system between zero and full load - Differences between increasing and decreasing load outputs (hysteresis) Different weighing applications can have different accuracy requirements and priorities. The importance and relevance of these are best illustrated by the following examples:

SILO WEIGHING SYSTEM

Such systems are typically used to manage stock control for essential raw materials to ensure processes do not run out of product and to calculate inventory values for fiscal purposes. Required accuracy levels may be relatively low, with errors of ±0.5 -1% usually being acceptable. However achieving these levels long term is not as straightforward as it may first appear and it is important that key weighing elements such as load cells provide good long term stability.

Unlike many weighing installations, once the silo weighing system has been installed and calibrated the zero stability of system may not be checked for

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months or years, especially if the vessel does not become completely empty at any stage. Over time if the zero point of the weighing system changes, then the displayed weight will not represent a true contents value even though any differential weight readings may appear to be consistent.

BATCHING AND RECIPE FORMULATION

By contrast, batching and recipe formulation systems have different fundamental requirements. High quality load cells must be used but the weighing process usually takes place over a defined, relatively short period. This means that the system can be reset to zero before each batch thereby improving short term accuracy capabilities, typically by up to a factor of 10. This allows small amounts of minor ingredients to be added with acceptable precision. The short weighing period also minimises the effects of any temperature changes. Here good repeatability can be more important than overall accuracy.

ENVIRONMENTAL CONSIDERATIONS

The ability for key weighing system elements to provide long term reliability is essential, especially in harsh environmental conditions. Material of construction, surface finish and sealing levels for critical equipment such as load cells play a key role. In the absence of clearly defined sealing nomenclature for load cells, manufacturers adopt the IP rating system (NEMA in the US). Unfortunately the IP system only refers to water ingress and does not give useful information with regard to chemical compatibility. This emphasises the importance of regular preventative maintenance discussed below.

TEMPERATURE EFFECTS

Temperature changes can have important adverse effects on weighing system performance especially for outdoor systems. Key issues are the rate of temperature change and differential heating/cooling. Rapid or excessive temperature changes affect load cell compensation performance and also impacts on load introduction (cosine error) through expansions and contractions.

ATEX WEIGHING SYSTEMS*

Certain weighing applications take place in designated hazardous areas (ATEX), where the presence of dust and gases together with oxygen (air), presents the finite chance of an explosion occurring through sparks or heat sources above critical temperatures. It is of paramount importance that any ATEX weighing system must be designed and installed by fully qualified, competent engineers.

‘normal’ and ‘fault’ conditions. (Note: load cells are classified as non-energy storing devices) This is normally achieved through the use of zener barriers between the instrumentation in the safe area and the load cells in the hazardous area. Alternatively specialist instrumentation is available that can be installed directly in certain hazardous areas, removing the need for separate barriers.

Weightron’s D440IS hazardous area indicator can operate in Zones 1, 2, 21 and 22 without the need for additional zener barrier protection. This minimises installation time and cost.

SYSTEM AND STRUCTURAL INTEGRITY

For new installations it is essential that structural design factors are consider during the design phase. If process weighing systems are retro-fitted to existing tanks, hoppers or vessels, the installation will almost certainly involve mechanical changes to the support structure. It is therefore important that this does not adversely affect the structural integrity of the system.

Such considerations are particularly important for large vessels, especially those installed out doors. Key factors can include wind forces and seismic activity. (The UK, for instance, has a surprising number of earthquakes which can test the integrity of weighing systems even though they register relatively low readings on the Richter Scale). Any restraints, such as check rods, used to maintain integrity can have adverse effects and must be carefully designed and installed. It is therefore essential that expert structural advice is taken both during the design phase and installation.

PIPE WORK AND OTHER FORCE SHUNTS

Very few process weighing systems stand in isolation without external attachments such as pipe work, gantries, ladders and other force shunts.

Anything connected to the weighing systems can, to a greater or lesser degree, have an adverse effect on performance. Particular care should be taken with silo weighing systems where several vessels may share a common support structure. So called ‘vessel crosstalk’ can occur whereby weight changes in one vessel are erroneously detected and measured in adjacent ones. However careful design can minimise the problems and ensure any force shunt effects are repeatable.

SELECTING THE CORRECT TYPE & CAPACITY OF LOAD CELL

Load cells form the basis of over 99% of process weighing systems. Selecting the correct type and capacity is a critical issue that needs careful consideration from the outset. The key factors in the decision process must take into account:

- The overall capacity of the weighing system - The ‘dead’ or ‘empty’ weight of the weighing system sitting on the load cells - The working range of the weighing system - Any overload requirements (e.g. wind forces, shock loading, vibration, seismic forces) - Environmental factors (e.g. wash-down, chemicals, temperature changes) - Accuracy requirements - Legislative requirements (e.g. Legal for Trade, ATEX) It should be remembered that in many applications, the actual live working range of the load cell (and hence the available electrical output) will be reduced depending on the dead weight of the vessel and any overload requirements.

This can have an important affect on performance and further endorses the need to ensure load cells are of the highest quality.

Operationally, weighing systems essentially fall into two main categories compression and tension, depending on whether the vessel or similar ‘sits on’ The weighing system must also be made up of fully ATEX certified components.

Hazardous areas are divided into different Zone Classifications – Zones 0, 1 and 2 for gases, 20, 21 and 22 for dusts. The classification of each zone and the methods of ensuring electrical equipment cannot cause explosions are defined through European Directives under the auspices of CENELEC. Directive 94/9/EC covers equipment, whilst a complementary Directive, 1999/92/ EC, is specifically concerned with worker safety and places requirements on employers whose staff may work in an explosive atmosphere. *ATEX legislation is mandatory in Europe and is also accepted in many areas of the world. However the US system is controlled by Factory Mutual (FM). (There is close cooperation between FM and CENELEC) For individual applications, the plant is divided up into so-called hazardous and safe areas. There are a number of ways to provide protection for weighing equipment, depending on the zone classification and working environment.

The most common way is based on intrinsic safety which essentially limitsthe maximum energy that can be applied to the load cell under clearly defined

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PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

or is ‘suspended from’ the load cells. The main types of load cells used in process weighing are:

- Single point cantilever - Single ended bending beam - Shear beam (single and double ended) - ‘S’ tension beams (bending and shear) - Compression canister - Ring torsion Material of construction includes aluminium, plated tool steel, painted tool steel and stainless steel.

The methods of sealing critical load cell components (strain gauges, cabling etc) range from simple potting up to full weld sealed with glass-to-metal cable entry. The latter can provide sealing levels of IP69K, making them suitable for hot washdown areas. Any final decision in the selection process will almost certainly involve a level of compromise to optimise performance versus system integrity and environmental compatibility.

MOUNTING HARDWARE

In the majority of applications, installing load cells without the use of proprietary mounting hardware can be difficult and very unsatisfactory. Well designed hardware not only plays an important role in terms of load introduction, vessel restraint, lift-off protection and overload protection, but also facilitates load cell fitting and removal.

CALIBRATION PROCEDURES

Calibration is a critical process in ensuring initial verification and ongoing weighing system performance. Essentially, calibration involves the checking of weighing system performance by applying known loads (these may be physical or electrical) over as wide a part of the weighing range as practical. There are a number of recognised methods of applying load, each with there own merits and precision. Clearly the type of weighing system plays a major part in deciding on the method of calibration. For instance, it is quite simple to add relatively small amounts of calibrated weights to a platform scale or small hopper, yet this becomes very difficult with large vessels. The main calibration methods are;

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

- Use of dead loads (calibrated weights added to system) - Substitution (previously weighed load (via weighbridge or similar) added to vessel) - Flow meter (vessel filled with known amount of water measured via flow meter) - Force calibration (known loads applied via calibrated load cells and hydraulic jacks) - Load cell output calculations Where practical, the design of weighing systems should take into consideration how the calibration will be achieved. This may require the inclusion of additional structural components.

MAINTENANCE

It is prudent to utilise the expertise of an external service provider to ensure ongoing reliability, safety and performance for process weighing systems.

Regular checks on calibration and system integrity will prevent expensive and time consuming breakdowns, whilst protecting revenue. In parallel it is also advisable that the user carries out simple regular checks on weighing systems as part of a structured in-house preventative maintenance regime. This can highlight problems including product build up, leakages that can cause component failure, unwarranted structural changes and mechanical damage.

Note: it is essential that electric welding is not carried out on weighing systems without seeking professional advice.

CONCLUSION

For optimum performance and reliability, modern process weighing systems should be based on a blend of sound mechanical design principles and versatile instrumentation. Flexible user-friendly software with inbuilt future proof capabilities will ensure comprehensive weight data management.

Key issues in the design and installation process mandate the use of qualified engineering expertise, especially for hazardous area applications and where structural integrity is an issue. Overall performance will always be affected by a range of environmental and operational factors. Cutting corners through the use of lower quality weighing components and instrumentation is false economy and will result in costly and time consuming ongoing poor performance and questionable reliability.

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HOSOKAWA MICRON USE AIRFLOW DYNAMICS SIMULATION TO OPTIMISE DOWNFLOW BOOTH AND WORKSTATION DESIGN Leaders in containment technology, Hosokawa Micron Ltd, are now offering customers the opportunity, to accurately check, at design stage, how the placement of objects, equipment and operatives in their downflow booth may affect airflow patterns and containment all important to the achievement of critical OELs. This leading edge airflow dynamics modelling package complements Hosokawa Micron’s existing ergonomic modelling to combine to deliver the most appropriate downflow booth solution to meet the customer’s needs and working practices.

Explains Carl Emsley, Hosokawa Micron Ltd, ‘Customers can see for themselves how airflow in the booth can be effected by protective screens, local extract ventilation, ancillary equipment, as well as the presence of an operative. The simulations represent conditions under normal established operations – starting with an empty booth demonstrating the down flow with primary ventilation system running. Further simulations can then be created to demonstrate how airflow would change when equipment or operatives are brought into the booth – this means Hosokawa Micron engineers can optimise positioning of equipment and operations within the booth; right at early design stage.

Using the airflow simulation package allows Hosokawa engineers to produce a proven downflow booth design for both standard and nonstandard units and is invaluable when designing for complex, multiuse operations.

Advanced computer modelling provides a visual demonstration of local extract as part of a downflow system.

With this software not only can we see the clear airflow patterns but workers can also see for themselves how they will be protected when handling potentially hazardous materials, giving them confidence in the task they are required to undertake. We can also say that in installations where downflow booths are placed within cleanrooms, where sometimes the ventilation systems can conflict, this new software is proving invaluable.’

For more information contact Hosokawa Micron Ltd, Runcorn, Cheshire Tel: +44 (0) 1928 755100 Email: info@hmluk.hosokawa.com Web: www.hosokawa.co.uk

TOP THREE REASONS WHY YOU SHOULD USE DUST-TIGHT VALVES

By Jason Marcotte, Vice President of Business Development, Vortex When it comes to selecting the right valve for your dry process application, there are many slide gates and diverter valves to choose from. Process valves are used to control the material flow in powder/bulk material handling systems (bins, hoppers, silos, downspouts, etc) in a variety of industries such as food, grain, milling, plastics, mining, and pharmaceutical. They can be used in gravity flow or low-pressure systems, as well as negative pressure systems, each system calling out for different equipment requirements.

A dust-tight valve can help you mitigate these potential side effects simply by the way it is designed. This can be a challenge when using soft polymers and packing as seals.

Many dust-tight valves designed today feature hard polymers (e.g. nylon, PET) as a sealing surface, because they tend to offer better wear characteristics for mostapplications. Constant force is applied against the valve, compressing the hard polymer into a positive dust-tight seal. It is important to pick a valve specifically designed for dry/bulk processes to control safety hazards, maintenance costs, and profitability in your plant.

SAFETY HAZARDS AND ENVIRONMENTAL REQUIREMENTS

Dust control has been given a higher priority in many powder/bulk processes over the past few decades. That’s because fugitive emissions from a valve into the atmosphere can both be detrimental to the environment and a potential safety hazard. Processing plants have an obligation to abide environmental regulations and prevent environmental contamination and pollution. Employee and plant safety play a large role in dust control, especially when it comes to processing hazardous dust explosive substances.

Dust-tight valves can be required in processing facilities as they can drastically reduce the percentage of fugitive dust. However, when replacing a regular valve with a dust-tight valve, it is important to verify that the connections between the valve and what sitsabove and below are tight.

For example, transition flanges need to be true and flat, with no bow, and gaskets need to be inspected and replaced if necessary. Keeping a good seal on every connection, minimizing the escape of dust from your process equipment, and inspecting and cleaning dust residues at regular intervals are all part of a robust dust control safety plan.

MAINTENANCE COSTS

The seal’s polymer material will eventually wear down and the valve will need to be resealed. Some manufacturers design valves with small slots in the body that let material slowly leak as an indicator that the valve needs maintenance. Choose a valve design that allows routine inspection without

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

removing it from the production line. Side access doors allow you to replace the old seals with new ones and start production back in minutes.

In comparison, valves featuring Teflon® rope require more downtime as the cartridge needs to be pulled out of the valve to remove the old rope and install a new one.

Eventually the valve will have to be taken out of service for seal replacement.

That is why it is important to select the right valve and seal materials for your specific application. The correct choice of materials will extend the valve’s service life by compensating for wear and tear, and provide an excellent material seal across the materials. Cast iron, carbon steel and aluminum are common valve materials for many powder/bulk applications, but more corrosive or abrasive materials require more durable alloy coatings such as hard polymer, stainless steel,or carbide for the material contact points to guarantee a long service life.

PLANT PROFITABILITY

Dust-tight valves are initially more expensive than other valves but tend to make up for the original cost difference in the long run in several ways. By keeping a tight seal, they limit the risk of material cross-contamination and increase final product quality. Their dust-tight design reduces material leakage in the plant and the atmosphere and directly affects a plant’s bottom line as it reduces concerns about product waste and pollution. Finally, dust-tight valves are easier to maintain and service. Many of them don’t require a production line shutdown longer than a few minutes at a time.

Overall, choosing dust-tight valves for your dry bulk applications will limit maintenance costs, reduce safety and environmental hazards, and reduce downtime. With so many valve options available, it is best to go with a company that has years of application experience and can help you pick the right valve for your specific powder/bulk process.

Many parameters have to be taken into consideration when purchasing a valve, including the type of material being processed, if the material is abrasive or corrosive, the particle size and temperature, and if the material is being conveyed by gravity, vacuum or pressure. Many dust-tight valves can be custom designed to meet your exact application needs and will often provide the best results.

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TOP TIPS FOR THE SUCCESSFUL HANDLING OF BULK MATERIALS

By Kevin Storey, Head of Sales, Portasilo (part of Shepherd Group Engineering) After hundreds of years of manufacturing using solid materials ranging from kitchen cupboard essentials like sugar to complex chemical compounds, mankind has achieved a degree of expertise. But our materials storage and handling skills are still evolving, and in fact, in too many cases there is little appreciation of the importance of understanding bulk material flow properties and handling behaviour.

Every material, including different grades of the same material or even those from different suppliers, have unique handling properties and understanding these is fundamental to the successful selection of processing equipment; its importance should never be underestimated as sourcing the right handling equipment and processes can ensure a plant makes considerable savings in terms of energy use whilst maximising productivity.

While there are numerous examples of plants handling similar materials, and experts describing the correct way to handle specific bulk particles, it always pays to do some homework that’s relevant to your application.

If possible undertake product handling trials at suppliers’ test facilities, visit sites that already handle the product and talk with not just the managers but the operators as they know the equipment and the peculiarities better than anybody. Advice can also be sought from official industry bodies such as the Solids Handling and Processing Association (SHAPA) http://www.shapa.co.uk/ or the universities who study the movement of bulk materials. However don’t follow existing arrangements blindly, processing equipment is continually being updated and there may now be a much simpler solution than those used previously.

COMMON MATERIALS

The handling of dry materials in loose bulk form is an engineering process which spans many industries from food to chemical to construction. The vast array of material grades and suppliers means it is now more important than ever before to test each material to be handled before an effective and efficient solution can be found.

The global marketplace and commercial pressures for more costefficient, sustainable and “green” manufacturing processes and endproducts are directly impacting the bulk material handling industry; engineers are designing ever more complex equipment and processes for handling a diverse and expanding range of materials.

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FOOD

WATER

CHEMICAL

NUCLEAR

ENERGY

Salt

Hydrated Lime

TiO2 (titanium oxide)

Iron Oxide

Wood Pellets

Sugar

Powder Activated Carbon

Gypsum

Magnetite

Dried Sewage SRF Wood Chip Draff

Chocolate Crumb

Quick Lime

China Clay

Ordinary Portland Cement (OPC)

Flour

Polymers

Limestone Filler

Pulverised Fly Ash

COMMON PITFALLS AND HOW TO AVOID THEM • Understand the material

You need to first understand the material to be handled; this is fundamental. If possible, it is always best to get a sample, preferably in a clear air tight sample jar, to test whether the product can be tilted to see HOW and IF the product flows at different inclines. This can have a bearing on vessel hopper angles, outlet sizes and type of discharge equipment. Also, gently shake the jar to see if the product retains air, and for how long! If it takes some time for the product to settle then when designing batch and volumetric systems different bulk densities will have to be considered ie aerated and settled can be dramatically different for the same product.

A common mistake, and one that is easily avoided, is considering whether the sample is truly representative of the full range of conditions.

In real life, system design has to account for a range of variables for the material. Will the product have consistent bulk density, particle size distribution, moisture content, temperature? Any change of these parameters could have a dramatic effect on how the product is stored

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

considered. Manual and now automatic ‘pigging’ systems can be builtin to aid this process and reduce downtime.

• Energy use

Energy saving, certainly for larger companies, is also a major consideration under the mandatory energy assessment scheme for larger organisations, the Energy Savings Opportunity Scheme (ESOS) https:// www.gov.uk/energy-savings-opportunity-scheme-esos. The amount of energy used now has to be considered as important as the purchase price of handling and processing solutions as financial penalties could be imposed by the regulator if an organisation does not comply.

and handled in a factory production environment.

Be aware that products, ambient and process conditions do change and that handling equipment and systems need to be able to operate throughout.

• Dust management

Providing a safe working environment should be a top priority for plant engineers. Some raw materials have the capacity to become explosive in sufficient quantities so it’s imperative to establish if its dust is combustible. Maybe the material in its original form is not dusty but when handled dust is generated. Bulk handling system design needs to protect against ignition of dust clouds that can cause initial explosions and then, if further dust is present in the workplace, a secondary catastrophic explosion!

• Maintenance and cleaning of equipment

Cleaning of the system and equipment might also be a major consideration either at the end of a batch or when changing recipe.

Can all internal areas of the plant be easily cleaned by hand or using an integral clean in place system (CIP)? Remember to check if this procedure cleans the product transfer pipework, which is normally not

TOP 10 MOST EXPLOSIVE MATERIALS: • Starch • Biomass • Flour • Malt Grist • Powdered Activated Carbon PAC • Coal • Dried Sewage • Polyelectrolyte • Whole Grain Rice Dust • Maize Grits PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

VIRGIN WOOD

ENERGY CROPS

AGRICULTURAL RESIDUES

FOOD WASTE

INDUSTRIAL WASTE & COPRODUCTS

Bark

Short Rotation Energy Crops

Straw

Wet Food Waste

Untreated Wood

Brash & arboricultural risings

Grasses & NonWoody Energy Crops

Corn Stover

Waste Oils

Treated Wood Wastes & Residues

Logs

Agricultural Energy Crops

Poultry Litter

Agricultural Residues

Wood Composites & Laminates

Sawdust

Aquatics (Hydroponics)

Animal Slurry & Farmyard Manure

Paper Pulp & Wastes

Grass Silage

Textiles

Wood Chips Wood pellets & Briquettes

Sewage Sludge

In depth look: Biomass

With many companies converting to using renewable energy resources such as biomass, there is growing demand for bulk materials handling solutions for this new and emerging market.

Biomass raw materials are generally explosive by nature so need to be handled carefully. There are a plethora of different materials and different grades, ranging from wood pellets from sustainable sources to the waste materials used by energy from waste plants.

The Solids Handling & Processing Association (SHAPA) has produced a technical guide “Best practice guide for handling of Biomass” which is a useful resource for design engineers and procurement managers responsible for specifiying or managing equipment for the handling of biomass http://www.shapa.co.uk/technical.php.

The classifications of biomass include: virgin wood; energy crops; agricultural residues; food waste; and industrial waste and co-products.

In all cases, a detailed assessment of the flow and handling properties of the raw material must be made before storage, handling and processing solutions are procured.

Government incentives and tough conditions for UK farmers have driven the huge uptake in biomass boilers at smallholdings across the nation.

While the financial returns and improved heating efficiency cannot be ignored, there’s no doubt that safe storage and handling of a diversity of biomass fuels must be considered by anyone considering switching to this type of energy generation.

Energy from waste processes can use materials from municipal, industrial and even household sources and so any storage and handling solutions must be designed taking all variables into consideration. The potential for blockages and risk of explosions is greatly increased if the flow properties of the materials to be handled are not accurately calculated before the equipment is sourced.

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ECONOMICAL DUST SUPPRESSION FOR LARGE SPACES Any process that handles solid materials is likely to produce dust. Once airborne, fine dust becomes a significant health hazard, especially when it contains silica. The exposure limits for respirable silica are currently 0.1mg/ m3reduced still further. To achieve these levels it is essential to make use of all available dust reduction techniques. Often, in large buildings, vehicle movements alone will cause the limits to be breached.

Generally, the cost of dust collection and / or building pressurisation around common areas can be prohibitive both in capital and energy costs.

A far more cost effective approach is to use

fog to suppress airborne dust.

Respirable dust particles are so small and light that they are supported by air molecules. To eliminate airborne dust, this resistance to gravity has to be overcome. Fog works by using very small droplets of water, typically in the size range 5 to 20 microns. These water droplets are small enough to allow a particle of dust to stick to the droplet. The result is that the dust now becomes heavy enough to fall through the air column and is no longer a nuisance. If the droplet sizes are too large e.g. > 20 micron, then the dust particle just bounces off the water tension and remains airborne. By using a matrix of nozzles, fog is sprayed into the area and settles the dust.

A remarkable feature of fog is that when installed correctly, it does not wet the area.

Renby MicronFog™ is the cost effective solution for airborne dust in large areas.

Power and water consumption are both low. For further reduction in energy consumption, all pump variants are operated on an inverter as standard.

There are many uses for MicronFog™; this ranges from Dust Suppression in solids handling to food process Disinfection and from Humidification to process Cooling.

To find out more about Renby MicronFogTM and other dust containment techniques: Contact Renby Ltd on Tel: 01829 740913 now or Email: info@renby.co.uk Web: www.renby.co.uk

DCS DUST EXTRACTION FOR HUMDINGER FOODS At its manufacturing plant in Sleaford, Lincolnshire, leading snack foods manufacturer Humdinger Foods Ltd has recently invested in new dust extraction equipment from Dust Control Systems Ltd (DCS). Serving Humdinger’s new peanut coating line, the dust extraction system is designed to effectively contain and capture airborne starch dust from within the coating process.

DCS has designed and installed a complete dust extraction system, incorporating custombuilt extraction hoods, and ductwork which runs at high level in the coating room to an externally-sited filter plant. All the ducting and extraction hoods are constructed in stainless steel and the system is configured to ensure optimum extraction conveying velocities. A clean air input system is included, and the main ductwork also incorporates an APEX approved CARZ back-pressure flap valve to prevent the effects of a dust explosion from travelling back along ductwork into the coating room. The high performance pulse-jet filter unit has an airflow capacity of 4,400m3/hr and is fitted with special Dura-Life water-resistant filter media. Waste is discharged into a quick-release collection bin.

Nik Durrant, Humdinger Engineering and Health & Safety Manager, says: “Having a clean and dust-free food processing facility is vital to worker safety and the DCS plant contributes greatly to this end. We were also very impressed with the standard of work and the way DCS handled every aspect of what was a very time-contingent contract.”

For more information: Tel: 0800 040 7116 Web: www.DCSlimited.co.uk

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PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

DISCHARGE PROBLEMS WITH POWDER? – VENT YOUR FRUSTRATION

By Richard Farnish - Principal Research Fellow Department of Mechanical, Manufacturing & Design Engineering of University of Greenwich.

Reliable handling of powders through processes can give enough of a challenge for many plants, especially if the equipment used is not suitable for the specific need of a bulk particulate. Aside from the more obvious causes of powder discharge instability such as incorrect vessel geometry, poor feeder interfacing and wrong choice of feeding device, the issue of pressure profiles across a packed bed material is an additional problem that often goes undiagnosed when trouble-shooting plant.

The key issues associated with discharge instability where pressure gradient effects are present are; the particle size (and distribution) and the resulting gas permeability characteristic for the powder. Generally, the finer / broader the particle size distribution the less gas permeable the bulk will become – and conversely, th coarser / more narrow the particle size distribution the more readily gas will permeate through the bulk.

The mechanism of the problem lies in the accumulation of gas (that cannot bleed away rapidly enough through the powder) in the region of the outlet.

Such a ‘bubble’ of gas can either make the powder flow irregular (through a ‘raining’ of particles from the roof of a supported dome) or cause a complete cessation of flow through the outlet. If the process is interrupted in order to investigate the stoppage, it is often the case that apparent reason is found – evidenced by a feeder that is full of powder.

Of course what has occurred is that the time taken to halt the process and investigate the issue has allowed sufficient time for the gas ‘bubble’ to dissipate through the static bed of material – allowing the powder to reinitiate flow through the outlet. This type of problem can quite perplexing when trying attain steady state plant operations! Most often this problem occurs in situations where rotary valves feeding into positive pressure conveying lines have been interfaced directly onto the outlets of hoppers. If either the venting provision for the rotary valve is inadequate or absent, then the volume of conveying air leakage past the tips of the rotary valves has the potential of exceed the rate of dissipation through the mass of powder – giving rise to inconsistent valve pocket filling or complete flow stoppages. For some rotary valve installations vent arrangements may be present in a range of configurations ranging from ‘well thought out’ to ‘improvised’. A well designed vent arrangement is unlikely to give many problems, but the greatest risk lies in the use of vent arrangements that have been installed with little or no reference to the duty asked of them.

The most usual error in this respect is to use incorrectly size vent lines, the risk being that unless an understanding of the existing and service limit air leakage rates for the rotary valve are known the vent bore will be either too small or too large. In the event that the bore is restrictive a back pressure could develop to the extent that air egress from the valve pockets is restricted such that some air continues to enter the hopper.

If the bore is too large the risk exists that gas velocity within the vent line will be insufficient to transport the dust (invariably a feature of vented air) and saltation may occur in the line.

In instances where saltation develops, there is ultimately a risk of blocking which will mean that air can, eventually, only exit the valve through the hopper.

Fig 1 shows the effect of excessive air leakage on rotary valve pocket filling efficiency.

The issue of poor rotary valve venting is usually fairly straight forward to rectify through the use of information relating Fig 1 An example of air leakage to the rotary valve and plant operating reducing conditions. Flow problems related to pressure gradients across the hopper can be more difficult to diagnose in instances where poor ventilation of a feed hopper occurs. In such situations the absence of air ingress into the head space of a vessel can reduce discharge rates significantly. An example of this occurrence could be due to the progressive blinding of a vent sock, which is a particular risk where vehicle cartridge type filters are used which will hold dust on the inside – but may appear ‘clean’ on the outside. The common absence

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

Fig 2 Graph showing changes in discharge rates as a function of ventilation of a method for cleaning while in service tends to make ‘blinding’ a regular feature of the use of this vent method – particularly if installed in a relatively inaccessible position. This most definitely should not be considered a ‘fit and forget’ item!.

Fig 2 shows the effects of an absence of ventilation for a small vessel used to store and discharge a blend of alumina and magnesium powders (30/70% wt) through a range of three outlet sizes (diameter 15mm, 30mm & 50mm). This particular vessel operated in core flow (as does the vast majority of industrial equipment), see Fig 3. The blend used for the purpose of this demonstration was very free flowing, had the blend exhibited a degree of cohesion, it is quite likely that the flow of material would be erratic at the larger apertures sizes and halt altogether for the small outlet.

Fig 3 Illustration of core flow discharge – note the presence of a central flow channel.

Depending upon the bulk characteristics of the powder and the specifics of the process that it is being handled through, flow rates from the vessel can be limited to the amount of material that ‘rains’ or detaches from the ‘roof’ of a semi-stable non-flowing arch above the outlet.

Fig 4 Illustration of discharge rate dominated by rate of powder ‘rain’ from a semi-stable arch above the outlet In summary it is hoped that the importance of understanding and incorporating appropriate vent arrangements on feeders and vessels can be understood from the contents of this very brief overview. The basic principles of controlling air ingress to bulk powders can be readily grasped, but the effectiveness resulting from the implementation of such strategies will be largely defined by a consideration of the bulk particulate that is being handled. An investment of time in characterising such bulk behaviour in the context of the handling equipment design and operation at the planning stage of a project will invariably pay dividends later!

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Guest Feature

PUMPING SOLIDS

By Malcolm Walker, Marketing Manager, AxFlow Limited

When it comes to pumping solids in industries such as sewage treatment, mining or food there are numerous pump choices available to the process engineer because solids are relatively common in these sectors.

However, when it comes to the chemical processing sector the options are more limited due to a range of additional factors, including the need for chemical resistance, ATEX, higher temperatures and the financial pressures.

The question that the chemical processing engineer faces is: what is the best pump type and technology for the application? Getting the correct answer can, and will involve a degree of research and detailed discussions with manufacturers and distributors. Pumps designed to handle solids are often not the cheapest option, but when the costs of maintenance, production down time or even cleaning up an escape of corrosive liquids are considered then for many applications they almost always represent the most cost effective option.

The range of pumps that can be considered for handling solids laden liquids, slurries and pastes can be narrowed down to rotary lobe, rotary piston, reciprocating positive displacement, progressing cavity, hose, centrifugal and air-operated double diaphragm (AODD) designs.

Making a decision as to which type to select is dependent on several factors including the corrosiveness of the liquid, the nature of the solid content, the flow and differential head required by the process.

AODD PUMPS

Many engineers resort to AODD (Fig.1) pumps because they can be constructed from chemically resistant materials, while at the same time being extremely good at handling solids; these can be up to 76mm

Fig. 1 Wilden ProFlo

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in size while the inherent action of these pumps make them resistant to abrasives, components can be easily replaced and they are selfpriming. The absence of close fitting parts allows solids to pass through the pump without harm, whilst abrasive and viscous products can be pumped without any damage to the fluid characteristics. In addition, this pump can accommodate dead-heading during filling applications, a task that motor driven pumps are not able to handle effectively.

Unfortunately, AODD pumps have some intrinsic disadvantages.

Compressed air is required, this being a factor that can contribute to their notoriously high running costs, flows are limited to 50 m3/ hr and the flows do pulse even when the pumps are fitted with dampeners. Furthermore, AODD pumps cannot withstand particularly high inlet pressures and there are issues relating to the lack of product containment, should the diaphragms rupture. This particular aspect is being addressed through the development of new robust designs that are manufactured from solid blocks of chemically resistant plastic, and with robust bolting arrangements to improve containment and pressure resistance.

HOSE PUMPS

Hose pumps (Fig.2) are an extremely popular option for pumping slurries with a solids content of up to 80%, and can deliver flows up to 90 m3/hr. The extensiverange of chemically resistant hoses now available has resulted in the pumps being suitable for handling many of the most demanding chemicals.

The hose pump is a positive displacement pump where the fluid is contained within a hose or tube inside the casing.

The fluid is moved into and out of the tube/hose by the action of rotating rollers or shoes which alternatively compress and relax the accurately and without any variation in the volume, making it an ideal proposition dosing requirements.

Fig. 2 realAx RP40 What’s more, where chemicals of a high value are involved, the pump is economic because at the end of the processing cycle or operation, the pumping motion can be reversed and any fluid remaining in the hose/tube can be returned to its source for future use.

Indeed, when faced with a corrosive slurry hose pumps are often the only option capable of handling the combination of corrosion, solids and abrasion. But, like AODD pumps should a problem of leakage does exist as the rupture of the hose can be disastrous. Other factors that come into play when the pumps is being considered relate to the flow, which is far from smooth, the limitations of the inlet pressure and

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

Guest Feature restriction on the maximum temperature.

PROGRESSING CAVITY PUMPS

Another common choice for transporting solids and slurries in chemical industry applications is the progressing cavity pump. They represent a simple and robust design that can deliver flows in excess of 200 m3/ hr added to which they have been around for many years, so giving them an air of credibility.

The key elements of this pump are the rotor and stator, the rotor being a helical worm that moves in an eccentric manner within the nonrotating stator. In this way the fluid is transported through the pump in a continuous low pulse motion. Where the accurate dosing of high and low viscosity fluids containing solids is the goal, then it is a popular choice.

Drawbacks that can be encountered include the rather limited range of materials used for construction and component wear which can be quite fast, resulting in the need for regular replacement. Their susceptibility to many types of failure places an onus on the operator to maintain regular inspection and planned programmes of maintenance.

ROTARY PISTON PUMPS

The rotary piston pump (Fig.3) is a proven alternative to the rotary lobe pump within the chemical processing industry sector. Although classed as a rotary lobe pump, it employs an operating principle known as the external circumferential piston (ECP) where the arc-shaped rotary pistons, or rotor wings, travel in annular-shaped cylinders machined in the pump body. The resulting long sealing path reduces slippage and produces a smooth product flow without destructive pulses or pressure peaks, and without the need for valves or complex parts. However, unlike progressing cavity and rotary lobe pumps, they are not adversely

It is a simple design that allows solids to pass through the pump without choking the impeller, so considerably reducing pump wear and the potential for blockages.

The fully recessed cup-shaped impeller and free passageways within the pump casing offer almost total freedom from blockages where solids and fibrous materials can be encountered in process waste water treatment plants. Suitable for ATEX certification, 316 stainless steel stainless steel impellers coupled with mechanical seals incorporating Viton or FEP are the recommended option for the chemicals industry.

It is important not overlook the small number of manufacturers which manufacture ATEX certified lined ISO 2858 pumps that are designed to pass solids. Taking Wernert (Fig.5) as an example, their pumps can be supplied with open impellers, larger internal tolerances, flushed seals and a hard wearing polyethylene lining if required. Significantly, they can handle liquids with up to 15% solids that can be as great as 7mm in diameter.

Fig. 4 The Wemco.

Fig.5 Wernert pumps Fig. 3 Waukesha U2 affected by slurries which have a propensity to settle in the pump.

Where solids are involved, the large fluid cavities of the rotors, together with the large easy-entry anti-cavitation ports enable efficient pumping.

Maximum service life even under severe operating conditions where fluids are non-lubricating or abrasive can be achieved, because there is no contact between the bearings and the pumped fluid.

The rotary lobe pump provides an alternative to the rotary piston pump, employing timing gears which eliminate contact between the rotors and enables them to handle non-lubricating fluids. There are various designs of rotor, including bi-wing and multi-lobe options. Providing low shear and gentle handling of the liquid, thereby minimising product degradation, rotary lobe pumps are also easy to clean in place (CIP) or strip clean between operations for batching applications.

CENTRIFUGAL PUMPS

The final category to be considered is the centrifugal pump, which is often ignored within the chemical industry when it comes to selecting pumps for handling solids. There is a misconception that there aren’t any chemically-resistant centrifugal pumps capable of handling solids.

It is a situation that does need correcting.

Centrifugal pumps that feature a vortex impeller (Fig.4) in stainless steel provide an excellent and well-proven solution. In operation, a whirlpool effect is formed in the volute by the rotating recessed cupshaped impeller extending into the suction line, drawing the liquid/ solids into the pump and then quickly through the discharge. This motion minimises the fluid/solids contact with the impeller and volute.

PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement

AN ALTERNATIVE APPROACH

As a result of AxFlow’s experience within the food and beverage sectors, and its large portfolio of pumps, the company takes a more holistic approach to pumping solids and abrasives. This approach attempts to mitigate the problem at source by reducing abrasion, by reducing the liquid’s velocity or smoothing out its flow, and for large solids by using a pump with a more gentle pumping action, or a pump that transfers the solids without taking them too deeply into its chamber.

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NEW AND IMPROVED ‘SLIMLINE’ CHECK SIEVE UNITS FROM FARLEYGREENE Carrying on from their recent updates to the linear conveying sieve and rotary centrifugal sifter units, Farleygreene have updated their already successful ‘Slimline’ straight through check sieve to include new features that have been part of ongoing development by the company.

This range of sieves is primarily designed to pass material straight through a mesh screen to remove any contamination from bags, silos, drums etc… and can incorporate an under screen rare earth magnetic separator to remove any ferrous metal. The unit can fit into existing lines due to its low height profile or into a debagging station which can dispense into containers or can connect to any type of convey line, mechanical, vacuum or pneumatic.

The new ‘SLIMLINE’ unit incorporates all of the features below: - All stainless steel vibrating body as standard - 316 stainless steel mirror polished contact parts as standard - 550, 950, 1250, 1550mm diameter units - Energy efficient electric vibratory motors - ATEX zone 21 II 2 D as standard - FDA approved materials - Metal detectable seals & gaskets - Fits into narrow spaces as low as 350mm - Optional mobile frames & sacktipping station with dusthood - Inline vacuum / pneumatic transfer model All Farleygreene’s machines come with a 24 month warranty, full support for spares and a rapid response remeshing service. Units can be trialled in their new test facilities in Hampshire or the test can be carried out on site.

For more information contact Farleygreene Ltd, Mapledurwell, Hampshire.

Tel: 01256 474547 E-mail: info@farleygreene.com / Web: www.farleygreene.com

A BREAKTHROUGH IN POWDER FORMULATION

The Virtual Powder Blending Laboratory is a breakthrough in powder formulation, allowing formulators in any industry sector to select from powders in a database, experiment with blending them in a virtual laboratory, and predict the properties of the finished blend.

It can also predict the effect of adding liquid to the surfaces of the powders (both oil and water) and the effect of “free-flow” additives such as silicon dioxide and others.

As the development has been funded by the UK Department of Environment, Food and Rural Affairs and a number of food industry collaborators, the work so far has focused on food applications (for example snack flavourings) but work has also been undertaken with mineral and pharmaceutical powders. It is expected to progress and evolve over time, for use in other groups of powders and industries.

For more details contact Rob Berry on Tel: 020 8331 8646 or E-mail: wolfson-enquiries@gre.ac.uk / Web: www.bulksolids.com

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PROCESS INDUSTRY INFORMER July 2015 - SHAPA Supplement