S MECHANICAL A ENGINEER June 2016
Publication of the SA Institution of Mechanical Engineering, incorporating News of Associate Organisations
LOCATION OF WIND FARMS DROPPING FEE SCALES
Chris Reay
Chairman of the Working Committee: Communications (SA Institution of Mechanical Engineering)
Despite the difficulty in making the decision, more people are making significant career changes and in addition are moving jobs more frequently. However, it is possible to make a career change and remain in the wrong career
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S MECHANICAL A ENGINEER
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Vaughan Rimbault
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Moses Sekatane, CEO of Ithuba Valves
The refurbishing of valves is an important and valuable service because many industries have to operate within extremely tight budgets
Manufacturing top quality valves is a passion
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Able to easily meet a wide range of needs from the design and manufacture of very specific valve types, with very high tolerances
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Philani Mngadi, Managing Member
find out if you qualify to #joinourtable at pps.co.za PPS is an authorized Financial Services Provider.
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Philip Janssens
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Designing with BIM boosts construction phase performance
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Figure 1. Two cutaway sections of the Corflex pinch valve sleeves. The one on the right is for relative high pressure applications, it is reinforced with 2 or 4 ply of steel wire depending on pressure required. The one on the left has 4 ply of much larger size wire, which is used for very much higher pressure applications.
Figure 2. Closed pinch valve sleeves
Figure 3.
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Figure 4. Experimental rig to determine closing pressures
Size 250mm 300mm 350mm 450mm
10 Bar 13 tons 17 tons 23 tons 35 tons
16 Bar 18 tons 24 tons 34 tons 51 tons
25 Bar 27 tons 38 tons 49 tons 77 tons
500mm
41 tons
61 tons
88 tons
40 Bar 39 tons 51 tons 73 tons 115 tons
Table 1. Force required to close and seal pinch valves with no added safety factor.
Figure 5. The valve is closed from both sides with the hydraulic cylinders firmly attached to the valve body using 4 x large diameter hi-tensile bolts
Two high pressure 500mm valves were supplied to MWS in Stilfontein for a working pressure of 25 bar. The valves have four trunnion mounted 200mm diameter non-rising hydraulic cylinders, two on each side of the valve producing a combined force of 120 tons.
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Angie Sรกnchez
Description of the study area
Environmental
Restricted: no-go areas
The site identification group
Technical component
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Criteria
Baban & Parry (2000)
PGWC (2011)
DEA (2011)
Proposed for this study
Criteria
Baban & Parry (2000)
Planning Distance to single dwelling and rural areas Distance to towns Distance to cities
500 m
2000 m
500 m
1 000 m
2000 m
Proposed for this study
Slope and elevation
< 10%
Distance from ridge lines
1:4 slope
< 8°
500 m
<10°
500 m
Enviromental
Distance to national roads
3000 m
3000 m
Distance to local roads
500 m
500 m
Distance to provincial tourist route
DEA (2011)
Technical
400 m
800 m
PGWC (2011)
500 m
National parks and natural reserves
1000 m
Protected natural environment, area of ecological value/special scientist interest
2000 m
10 000 m
2000 m
2000 m
1000 m
2000 m
4000 m
4000 m
Distance to local tourist route
2500 m
2500 m
Private nature reserves
Railway line
250 m
250 m
Ecologically sensitive area
1000 m
Distance to major power lines
250 m
250 m
Wildlife conservation area
500 m
Communication Towers
500 m
500 m
Mountain catchments
500 m
>8 degrees
500 m
250 m
250 m
Distance to coastlines of undisturbed scenic value
4000 m
1000 m
4000 m
500 m
500 m
200 m
200 m
2000 m
500 m
Distance to local wetlands
500 m
2000 m
Distance to bird habitats or avian flight paths where known
1000 m
500 m
Radio and navigation beacons
Omitted
Airport with primary radar
25 000 m
5000 m
Local Airfield
2500 m
3000 m
Distance to streams, lakes and rivers
Military zone, national security sites
15 000 m
15 000 m
Distance to flood line
500 m
500 m
Distance to major wetlands (ramsar sites)
Historic sits, heritage and cultural sites, national trust property
1000 m
Economical Wind resource
> 5 ms-1
Distance to national roads
< 10 000 m
Distance to national grid
<10 000 m
>8 ms-1
>5 ms-1 <10 000 m
Eskom tier approach
Eskom tier approach
Distance to important vegetation/ remnant vegetation, forest and wood lands
1000 m
500 m
1000 m
400 m (water bodies)
500 m (woodlands)
1000 m
Table 1: Summary comparison of different suggested criteria for wind farms location
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Criteria
Slope
0°-5°
0-8%
Ranking 5
Description Preferred
5°-7°
8-12%
4
Adequate
7°-8°
12-14%
3
Potential Sensitive
8°-10°
14-18%
2
Highly Sensitive
>10°
>18%
1
Unsuitable
Table 2: Suitability ranking criteria proposed for the technical component
Estimated energy generation
Figure 1: Site performance index. Scenario 2
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Figure 2: TAPM modelled annual average wind speed
Figure 3: Modelled vs. measured wind speed at Vrede Station. Sep 11
Figure 4: Time series of hourly electricity output, estimated vs. measured, at Klipheuwel wind farm (3 generators). Feb-Mar 2011
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Verification
Demand analysis
Figure 5: Hourly energy demand vs. energy production from wind
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Figure 6: Display of the MSE calculated for a typical winter month, assuming 10% penetration
Figure 7: Combined modelled results showing top 30 (black) and bottom 30 sites (red) for wind farm location
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Combined model results
Conclusion
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E-mail: sales@valve.co.za Exports: africaexports@valve.co.za
Paul Marcroft
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POWER GENERATION NEWS
High Performance Polyurethane Seals The global wind energy industry must maintain high levels of reliability and availability. As the number of turbines in use worldwide increases, operation and maintenance is becoming an ever more significant business. It is a challenge that is compounded by the fact that turbines are often installed in remote places, from mountaintops to offshore locations. In modern wind turbines, the main shaft seals provide the first line of defence between the external environment and the critical main bearings and gearbox components. These seals play a dual role: protecting turbine components from contamination and stopping lubricants from escaping into the environment. Engineers at SKF have
developed a new generation of seals, the HRS range, specifically to meet the challenges of the wind energy industry. The seals are manufactured from G-Ecopur polyurethane, which is an ozone, UV and water-resistant material that offers excellent wear resistance compared with the rubber materials commonly used elsewhere. G-Ecopur also allows the HRS seals to be machined with an exceptionally smooth surface. This means that the seals have less of a tendency to make grooves in the surface of the shaft, helping to maintain system performance over the life of the turbine. The seals’ smooth outer surface prevents the leakage of lubricant between the seal and housing, a condition that commonly affects rougher phenol-impregnated fabric seals.
The whole HRS range is available in solid or split designs. Solid seals are designed for installation during manufacture where operators can access the
end of the shaft. Split seals are ideal for in-service replacement, or manufacturing applications where there is no access to the end of the shaft. HRS seals are manufactured in a full range of standard sizes to suit modern wind turbine applications and can also be made to meet specific customer requirements. SKF, www.skf.com
New Solar Plant Enel, through its subsidiary Enel Green Power RSA (“EGP RSA”), has completed the Tom Burke photovoltaic power plant in Limpopo, and connected it to the grid. With an installed capacity of 66 MW, the Tom Burke photovoltaic power plant is capable of generating up to 122 GWh per year. This output is equivalent to the annual consumption needs of around 38 thousand South African households, while avoiding the emission of over 111 thousand tonnes of CO2 into the atmosphere each year.
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The PV power plant is supported by a 20-year power supply agreement with Eskom, as part of the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP) tender promoted by the government which awarded the project to the Enel Group. In addition to Tom Burke, Enel’s South African renewable subsidiary EGP RSA currently owns and operates the recently-completed Paleisheuwel photovoltaic power plant (82.5 MW) situated in the province of the Western Cape and the 10 MW Upington
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photovoltaic power plant situated in the Northern Cape Province. EGP RSA has a further 364 MW of projects currently under construction: the Adams (82.5 MW) and Pulida (82.5 MW) photovoltaic plants and the Nojoli (88 MW) and Gibson Bay (111 MW) wind farms. Moreover, in 2015 the Enel Group was awarded a further five wind projects for a total capacity of 705 MW following the fourth phase of REIPPPP tender. Enel www.enelgreenpower.com
Simon Berry, director, Fresh Projects
Cloud-based business management solution screenshot
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An accessible and clear guide on how to grow your business through export
E
ngineers receive a broad education in the nuts and bolts of machinery, equipment and systems but not much attention is paid to the commercial aspects of running an engineering concern.
“Engineering World”, a new annual publication being produced by Promech Publishing, in co-operation with the SACEEC (SA Capital Equipment Export Council), will serve to make financial and commercial decisions easier for engineers to make. The publication will focus on the export market but also on local content as a reliable tier of suppliers and supplier industries is vital to local manufacture. SACEEC will share its experience and expertise on a variety of elements that must be taken into account to become a successful exporter, such as:
Freight forwarding Tax matters Forward cover Deciding on what to sell to whom The culture and customs of the export destination country Building a robust supply chain The financial implications of exporting Marketing internationally Building a presence in the destination country Getting the correct legal advice. The SACEEC has assisted many companies in navigating the pitfalls of going over our borders. They remain committed to growing South African exports and have generously agreed to share their knowledge with the readers, in the interests of the country and our economy.
Eric Bruggeman, MD of SACEEC: “What you didn’t think to
ask? We trust that this first-of-its-kind publication will prompt capital equipment companies, who are contemplating the export route, to ask the right questions before setting off on what can only be described as an exciting and potentially lucrative journey.”
Contact the SACEEC on admin@saceec.com For advertising, contact Louise Cresswell on Tel (011) 781-1401 or 071 886 1263 For editorial: contact Patricia Holburn (B Comm BA Eng.Comm) on pathl@mweb.co.za
Associate Professor Natasha Sacks
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MARKET FORUM
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MARKET FORUM
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Collaboration and Integrity “Two key factors for the success of infrastructure projects in Africa is the collaboration between the private and public sector, while using a third party for early engagement and de-risk; and integrity in the design process,” says Poya Rasekhi, Chief Executive Officer of Arup SA.
Poya Rasekhi
“Integrity in design cannot be compromised in any way. We see substandard designs working their way into developments more regularly due to the pressure of price and lack of upfront planning and design work. In a recent Arup survey on the real cost of poor design, we discovered that in developed countries between 4%-5% is spent on design, while in developing countries it is between 2%-3%, often resulting in an over run of 30% to 40% of capital cost.
These costs can be easily reduced in Africa through embracing effective planning and good design.” Commenting on big African infrastructure to watch, Poya adds, “The Renewable Energy Independent Power Producer Procurement Programme (REIPP) is globally recognised as a success. “An indication of the importance that Arup SA places on renewable energy resources is evidenced by the fact that five years ago we had no renewable energy team to speak of. Our SA team is now regarded as the global leader of excellence for renewables within Arup,’’ he concludes. Arup Tel: (011) 218-7882 www.arup.com
Soil turning ceremony - From the left are Riaz Haffejee (CEO: SRSA), Michael Mabuyakhulu (MEC for Economic Development, Tourism and Environmental Affairs), Rob Davies (Minister: Department of Trade and Industry) and Yutaka Kuroda (Executive Director, Sumitomo Rubber Industries Ltd).
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