MechChem Africa December 2018

Mech Chem DECEMBER 2018 AFRICA

The perfect blend of experience and drive

This month: GE announces industrial scale AM system

Collective accountability to clean up SA

Mega train manufacturing ramps up in Dunnottar

Using pumps to generate electricity

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14

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Pump systems, pipes, valves and seals 8 Using pumps to generate electricity

P U B L I C A T I O N S CR O WN

A forward-thinking municipal technical team serving the requirements of the Drakenstein Municipality (Wellington) in the Western Cape has designed one of the country’s largest pump and turbine stations, which will be used for pumping water to the nearby town of Paarl during dry periods and to generate electricity for the city during the remainder of the year. 11 New levels of hydraulic efficiency in slurry applications 12 Mill circuit pumps reduce operating costs Local manufacturing and food processing 14 Mega train manufacturing ramps up in Dunnottar On Thursday, 25 October 2018, South African President Cyril Ramaphosa officially opened Gibela’s train manufacturing plant in Dunnottar, east of Gauteng. MechChem Africa talks to systems integrator, David Blackwood of DESign about the modern systems installed to ensure high integrity fabrication. 16 Steel processor extends stretcher leveller capacity 17 MAP, poultry and the cold food chain Power generation, sustainable energy and energy management 18 Integrated solutions key to growing Africa’s power generation As African countries work to develop their power generation capacity in the most cost effective ways, the key will be to find integrated solutions that attract investment throughout the value chain, argues Alastair Gerrard, Integrated Solutions executive at Zest WEG Group. 20 Key to a sustainable future: advanced water electrolysis Extensive tests performed at the National Engineering Laboratory’s (NEL) flow test facility in Glasgow, UK, have confirmed that thermowells with a ScrutonWell ® design have no tendency to vibrate. Kai Grabenauer, product manager for WIKA’s electrical temperature measurement business in Europe, presents the findings and the principles underpinning the ScrutonWell design. 25 The uprising – a natural gas movement Environmental management and cleaning technologies 26 Collective accountability to clean up SA Kate Stubbs, director of business development and marketing at Interwaste, summarises the current status quo with respect to waste management and urges all stakeholders – Government, corporate South Africa and individual citizens – to play a more proactive role in reducing waste-to-landfill and to put more effort into recycling. Innovative engineering 30 GE announces industrial scale additive manufacturing system GE Additive has announced that its first Concept Laser M-Line Factory systems for industrial scale additive manufacturing will be delivered to customers during the second quarter of 2019. REGULARS 21 Renewable energy projects on home ground Chemical, petrochemical, oil and gas 22 Endurance test for vortex breakers

Published monthly by Crown Publications cc Cnr Theunis and Sovereign Streets Bedford Gardens 2007 PO Box 140, Bedfordview, 2008 Tel: +27 11 622 4770 e-mail: mechchemafrica@crown.co.za www.mechchemafricamagazine.co.za Editor: Peter Middleton e-mail: peterm@crown.co.za Advertising: Brenda Karathanasis e-mail: brendak@crown.co.za Design: Darryl James Publisher: Karen Grant Deputy publisher: Wilhelm du Plessis Circulation: Brenda Grossmann The views expressed in this journal are not necessarily those of the publisher or the editors. P U B L I C A T I O N S CR O WN P U B L I C A T I O N S CR O WN 2015/02/10 01:17:09PM

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Front cover: Mixtec South Africa info@mixtec.com www.mixtec.com

2 Comment: An inhospitable earth or urgent green spending? 4 Cover story: Mixtec: SA’s agitation and suspension expert. MechChem Africa talks Rudi Swanepoel about the company’s innovative EDICT agitation systems. 6 SAIChE iCHEMe: Member Group News 28 Product and industry news 32 Back page: Robot welder unveiled at SAIW

December 2018 • MechChem Africa ¦ 1

An inhospitable earth or urgent green spending?

I ts COP time again. The United Nations Frame- work Convention on Climate Change (UNFCCC) will hold its 24 th annual Conference of the Par- ties (COP24) from December 2 to 14. At the ‘breakthrough’ Paris Agreement of 2015, 175 Parties, including the US, China and the EU, agreed to specific greenhouse gas-emissions mitigation, adaptation and finance measures for implementation from 2020 onwards. COP24 in Katowice, Poland is mooted to be ‘Paris2.0’whererulesandguidelineswillbeestablished to ensure countries deliver on these commitments. After 24 conferences the mitigation specifics are yet to be established! On Black Friday, the US’s frenetic shopping holi- day and one of the best days of the year to ’bury’ bad news, the US Congress chose to release its Fourth Annual ClimateChangeAssessment. Aquote fromthe Summary Findings on the impacts on the US economy reads “Without substantial and sustained global mitiga- tion and regional adaptation efforts, climate change is expected to cause growing losses to American infrastruc- ture and property and impede the rate of economic growth over this century.” By2100, according to the report, givenwarmingon the current trajectory, the cost to the US economy in crop damage, lost labour and extreme weather dam- ages could exceed US$500-billion per year; almost double the economic blow of the economic crisis in the late 2000s. DonaldTrumpand theWhiteHousehavedismissed these predictions, suggesting that they are based only on “most-extreme scenarios” and ignore the potential effects of technology. In fact, the assessment above is the ‘do-little’ scenario, which is exactly what Trump‘s Whitehouse is advocating. A report released in May 2018 by Stanford Uni­ versity scientists calculated that climate change, based on the world’s nations adhering to the Paris Climate Accord but still failing to limit the temperature rise to between 1.5 and 2.0 °C, would reduce global GDP by up to 15%. Based on the 2018 global GDP-projection of $87.51-trillion, this puts the annual loss, assuming zero growth for nearly 80 years, at US$13.1-trillion. Alarming indeed: and adhering to the Paris agree- ment is looking like a best-case scenario based on the WhiteHouse’scurrentstanceandpoliticalindifference elsewhere in the world. The UN’s ‘Emissions Gap Report. 2018’ , points out that CO 2 emissions are rising again, for first time in four years and that ‘global efforts to tackle climate change are way off track’ . The report points to economic growth as respon-

Peter Middleton

sible for a rise in 2017, but perhaps the converse, economic constraint, has been flattering emissions mitigation in the past few years. The Emissions Gap report’s analysis predicts that global emissions arenot likely to peak until 2030, ten years later than the Paris Accord’s 2020 goal. “There is still a tremendous gapbetweenwords and deeds, between the targets agreed by governments worldwide to stabilise our climate and the measures to achieve these goals,” said Gunnar Luderer from the Potsdam Institute for Climate Impact Research and one of the authors of the study. Emission mitigation must be increased five-fold to meet the 1.5 °C goal and, right now, the world is heading for a temperature rise of 3.2 °C by the end of this century. The study fingers countries such as Argentina, Australia, Canada, the EU, South Korea, Saudi Arabia, South Africa and the US as falling short of achieving their nationally determined contributions for 2030, whileon thepositive side, theUNisplacinggreat hopes on ‘non-state actors’: local, city and regional govern- ments, businesses and higher education institutions. More than 7 000 cities from 133 countries and 6 000 companies with at least $36-trillion in revenue have pledged to take climate action. The authors, however, believe this is just scratching the surface of the 500 000 publicly traded companies worldwide. It is clear that we are not doing nearly enough to reduce emissions tomitigate against the very real con- sequences of climate change. Governments theworld over are preoccupied with their political survival and that of their fragile economic recoveries and, as Trump proves, even when nations finally commit to action, progress is too easily overturned on regime change. A friend of mine has recently installed a R130 000 PV system at his home. He is rightly proud. My green commitment is limited to shuffling paper, glass and tin into differently coloured bags. We have to take urgent action if we want to avoid the decline of our planet into an increasingly inhospi- table place. That means we should all be prioritising loweringour carbonemissions, viaour lifestyle choices and our investments in cleaner technologies. We can no longer wait for government officials to make the right choices. Private industry, businesses, hospitals,factories,farms,schools,universities,church- es and homeowners all need to re-align their practices and technology choices towards lower emissions. Green spending now could still influence history, while doing nothing is likely to bring shame on our entire generation. q

MechChem Africa is endorsed by:

2 ¦ MechChem Africa • December 2018

MechChem Africa visits Mixtec SA at its Meadowdale premises and talks to the company’s sales and projects manager, Rudi Swanepoel, about the global success of the company’s innovative EDICT agitation systems. Mixtec: SA’s agitation and suspension expert

M ixtec founders, Timothy Clamp andWilliamBaguley, havebeen in the agitator business for several decades, initially with UK-based Kestner Industries, the original home ofMixertech-UK, which is nowawholly owned subsidiary of the SouthAfrican entity. “Mixtec SAbecame a standaloneOEMfor mixersandagitatorsbackin1984andwehave since grown into a global organisation with six fabrication facilities around the world: in South Africa, the UK, the US, Australia, Malaysia and Chile. In addition, we have four specialised agents: in France, New Zealand, Mauritius and Kazakhstan,” Swanepoel tells MechChem Africa . “Every Mixtec office has its own research and development department as well as design, engineering and commissioning per- sonnel who are trained to apply modern uid mixing technologies such as computational fluid dynamics (CFD) to any application and installation. We can also quickly tap into a wealth of design experience and expertise,

expanding our overall knowledge base and en- abling us to con dently satisfy our customer’s needs, no matter where they are located,” he continues. Predominantly servicing minerals’ processing applications, Mixtec is increasingly involved in the water and wastewater treatment, food processing, oil and gas, pulp and paper and other industrial fields. “We have now done several AMD projects, for example, developing themixers for agitating the coagulants and reactants in mine affected water to maxi- mise contact and optimise neutralisation and binding efficiencies,” Swanepoel explains. At the heart of the com-

Mixtec’s new four- bladed impeller, the

HA724, dramatically reduces shaft bending moments

pany’s success are its innovative impeller andblade technologies, all ofwhich are designed in-house,

and out-of-balance forces.

resettling and less efficient mixing in the top section of the tank. In minerals processing applications, the key requirement is to keep solids in even suspension across the whole tankvolumetomaximisecontactbetweenthe liquid and solid phases,” he explains. “Our latest EDICT system consists of a high-efficiency down pumping impeller together with an upper impeller that pumps up. This adds velocity to the solids initially suspended by the lower impeller by drawing them into the low-pressure area between the impellers and boosting their upward motion into to the upper portion of the tank. The solids then travel across the slurry surface to the overflow or back down toward the flow generatedby the lower impeller to repeat the cycle,” he tells MechChem Africa . Because of the better distribution of suspended solids, the EDICT systemrequires less power to produce the necessary flow rates, even when the impeller is required to be in very close proximity to the tank bottom. “Less power means smaller motors and gearboxes can be installed, which not only cost less, but they are also more energy efficient. In addition, the shaft, bearings, couplings and mechanical components are under less stress, so these systems tend to be more reliableand robust,” Swanepoel informs MechChem Africa . Further supporting Mixtec’s agitation optimisation efforts are its latest generation

in their R&D departments. “Our designs are subjected to CFD analysis and laboratory testing to ensure that specific requirements have beenmet. But nothingwe manufacture is standard,” Swanepoel notes. “Each solution is highly optimised to best suit

the agitation or suspension requirement.Wehavedevel- oped some unique designs, that offer much better en- ergy and mixing efficiencies than standard options on the market,” he says. Describing Mixtec’s EDICT innovation, he says that most top entry mixers in the mining industry use a dual down pumping system, which has two impellers on the same shaft that both pump down into the bottom of the tank. “These mixers pump material towards the tank floor, which forces the flow outwards towards the sides of the tank and then up the side walls. “From extensive CFD analysis, however, we have found that the dual down system results in flow ve- locity loss above the upper impeller, which causes faster

Rudi Swanepoel, sales and projects manager; Jonathan Clamp, director; and Timothy Clamp, founder.

4 ¦ MechChem Africa • December 2018

⎪ Cover story ⎪

An HA736 shaft manufactured in Mixtec’s Meadowdale facilities in Gauteng. high-efficiencyhydrofoils. “These impellers reduceop- erating costs and result in smaller more cost effective drives for solids in suspension applications.

Swanepoel suggests that retrofitting existing mixers with modern custom designs can often be im- mediately cost effective for mine operators, because the net recovery rates improve instantly. “We are alsoexperiencing success on tailings

“We have also introduced a four-bladed impel- ler, the HA724, which dramatically reduces shaft bending moments and out-of-balance forces. When usedwith the EDICT system, this impeller reduces the pumping capacity needed to achieve the same duty – typically to 85% of that previously required – resulting in further power savings. “Mostimportantly,though,becauseoftheopposing flows, there is greater interaction between solids and reagent gases, which improvesmineral recovery rates, directly increasing profits,” he adds. The original Mixtec EDICT system was developed back in 2005 in Mixtec’s R&D facility in South Africa. “To date, it has been successfully installed in hundreds of mining applications worldwide and it remains a superior choice for agitation within the minerals pro- cessing field,” Swanepoel says. Typical applications include general solids suspen- sion processeswhere homogeneity of solids, reagents andwater is critical, such as neutralisation, filter feed and anoxic/anaerobic leaching processes. Mixtec’s EDICT solutions have been applied in copper, gold, platinium, and phosphate concentrators and leach plants, with the carbon in leach (CIL) process head- ing the list. “For processing gold using carbon in leach (CIL) processes, for example, if the impeller tip speed is too fast, the carbon breaks down, which lowers the adsorption efficiency of the gold onto the activated carbon. This directly affects recovery efficiency,” Swanepoel explains. “We strive to understand our customers’ applica- tions indetail inorder toprovide thebest optimisedso- lution possible. We know about the limitation and are able to customise our designs, not only to overcome problematic issues, but also to implement solutions that optimise recovery rates,” he notes.

circuits in overcoming reliability problems. We were recently asked to look at a system where the mixer couplings were

shearing off. Using our impeller designs, wewere able to reduce the stresses and improve reliability, which resulted in a very quick payback period. “Our heavy duty 4000 Series agitators can often have impeller diameters of 8.0 m with shafts over 21 m long – and with two in-tank couplings, we can achieve a run out tolerance of only 3.0 mm, well be- low the industry-accepted average of 1.0 mm/m. We welcome the challengeofmanufacturing systems such as these,” he says. Swanepoel cites a phosphate project in Morocco: “We supplied this plant with pipeline slurry tank agitators that were manufactured in South Africa and exported to Morocco. These were 250 kW units that weighed 38 428 kg, were 20.5m longwith a shaft diameter of 508mmand impeller diameters of 6.8, 7.5 and 4.0 m, respectively,” he reveals. Also included in Mixtec’s range are 250 Series direct drive systems for open or closed tanks; 1000 Series gearbox-driven top entry open tank units; the 2000 Series closed tank units; the large indus- trial gearbox-driven 4000 Series; the 5000/5050 and

The slurry tank agitators in Morocco are

250 kW units that weigh 38 428 kg and are 20.5 m long with a shaft diameter of 508 mm and impeller diameters of 6.8, 7.5 and 4.0 m, respectively.

5500/5600 side entry and V-belt side entry units; and static inline mixing units. “We have spent over 35 years continually improving the agitation systems required by industry so that it cancontinually improve itsprocess efficiency, profitability and competi- tiveness – and the results are well proven.” Swanepoel concludes. q

December 2018 • MechChem Africa ¦ 5

Field-tested techniques for distillation processes and equipment A course by Henry Kister

From 29-31 July 2019, the KwaZulu-Natal SAIChE IChemE branch will be hosting a course on practical distillation technology by world-renowned distillation expert Henry Kister, which aims to give comprehensive coverage of distillation technology, with particular emphasis on the problems that can occur and how to solve them.

H enry Kister is a recognised spe- cialist with a vast background in all phases of distillation, includ- ing operation, troubleshooting, design, start-up and research. At Fluor he designs, revamps and advises on distillation processes, equipment and controls for the chemical, petrochemical and oil industries. He is also extensively involved in field con- sulting, start-up and troubleshooting assign- ments and in developing Fluor’s in-house distillation technology. He is the author of three textbooks, Distillation Operation ; and Distillation Design ; (McGraw-Hill Inc, 1990 & 1992) and Distillation Troubleshooting (Wiley

Interscience, 2006). He has published over 100 technical papers and presented this course over 500 times. Kister’s down-to-earth course, gives com- prehensive coverage of distillation technol- ogy, withparticular emphasis on theproblems that can occur and how to solve them. It providesanexcellentopportunitytodevelopa workingknowledgeofkeytechniquesthatcan promote trouble-free operation and reduce distillation costs. Ideally suited to engineering and supervi- sory personnel who are involved inoperating, troubleshooting, de-bottlenecking, designing and starting up distillation processes, the course content includes:

• Troubleshooting a distillation column and determine what may cause poor performance. • Evaluating existing column performance and developing new designs. • Avoiding common causes of capacity bottlenecks, tray damage, downcomer sealing problems, packed tower distribu- tor malfunctions and many other operat- ing difficulties. • De-bottlenecking a column to improve capacity and/or separation efficiency. • How to control and operate a distillation column. • Validating tower simulation models. Theprogrammeoutline, whichmaybe subject to change, includes: 1 Avoiding fractionation pitfalls? The key concepts of vapour-liquid equilibrium (VLE) and simulation traps are covered. Should we believe the simulation? Issues with close-boilers and non-idealities: why do some heavy components go up while the simulation thinks they should go down? CanVLE data be trusted or not? Multi-componentdistillation,composition profiles, side-draws, accumulation and cycling problems will be dealt with and what operators need to watch out for will be highlighted. 2 Troubleshooting distillation simulations: Does your simulation reflect the real world? This part of the course deals with how poor simulation can lead to incor- rect problem diagnosis. What validation checks areneeded?Howfar shouldwe go? Delegateswill be presentedwith sensitiv- ity analyses, graphics and directly useful tips for simulation troubleshooting. 3 Tray hydraulics and limits: Content for this session includes: Visualisation of vapour-liquid dispersions on trays, flood- ing, entrainment, weeping and dumping; along with flood mechanisms such as jet (entrainment), system limits, downcomer

6 ¦ MechChem Africa • December 2018

⎪ SAIChE IChemE news ⎪

backup, downcomer choking: Which one of these is limiting your tower capacity? The pros and cons of common tray types including sieve, moving valve, fixed valve and sheds: Which works well in fouling applications? Small holes and valves, the benefits and the traps. Flooding, what causes it, what affects it, how to predict it and are the predictions reliable? Are tray efficiency simulations andpredictions reli- able? Can the process be enhancedby tray modification? 4 Troubleshooting tray towers: Flooding and foaming symptoms: high differential pressures (dPs), reduced bottoms and others. Which can be trusted? Liquid and vapour sensitivity field tests: identifying the correct flooding mechanism. Tricks that will get you more information out of dPmeasurements. Gamma scans: applica- tions for diagnosing flooding, missing and damaged trays, foaming, and downcomer flooding. How to combine gamma scans with process checks to get the most out of the scans: the four keys to success. Do gamma scans ever lie? How to keep them truthful. 5 Troubleshooting packed towers: Rules of thumb for flooding pressure drop and packing efficiency. Simulation of hydraulic calculations: to trust or not to trust? Grid gamma scanning for detecting maldis- tribution, damage, distributor malfunc- tion, distributor and collector overflow. Distributor overflow: Death for packed beds! Somedosanddon’tsfordistributors. Can poor distributor feeding bottleneck towers? Circumferential surface tem- perature surveys: how to conduct them, what to avoid and the hidden secrets they reveal. 6 De-Bottlenecking: State-of-the-art trays and packings, strengths and weaknesses. Factors that favour trays and factors that favour packings. The pressure drop bonanza: why packings win in non-fouling vacuum services and in compressor suc- tion.Pitfallsuniquetostructuredpackings:

high pressure applications, oxidation, and shutdown fires. High-capacity trays such as Superfrac, VG Plus and MD: principles, tricks, and traps. Do they really give 30% more capacity than conventional equivalents? 7 Distillation control: Assembling control loops into an overall scheme; what works, which is better, what causes instability, and what impairs efficiency. The three most common causes of control assembly failure; no material balance control, fight- ing between temperature controllers, and level control on a small stream. Tips for avoiding problems: can controls affect revampsuccess?Besttemperaturecontrol locations: is there a reliable method for finding them? How can a temperature controller be fooled? Reboiler, condenser, and pressure controls: which loops work andwhichmisbehave.Howdeadpocketsin vapour overhead lines interfere with con- trols. Understandinghot vapour bypasses: why someworkwhileothersdon’t. Control systems that did not work. 8 Avoiding tower malfunctions: The 20 most common causes of distillation malfunctions: what trouble should we look for and prevent. Points of transition (feeds, draws, tower base): why these are some of the worst tower bottlenecks: how to diagnose these and remedy them. High tower base levels: how they induce premature flooding, even tray/packing damage and how you can prevent it. Instrument issues at the tower base: what to watch out for. Tray/packing damage: pressure surges due to water entering a tower full of hot oil or insoluble organics, other sources of tray damage and ways to avoid these. Some commissioning and startup issues: pre-startup inspection, blinding and unblinding, reverse flow, steam-water operation, washing, rapid pressuring/depressuring, drawing vac- uum, introducing liquid. Chimney trays: dos, don’ts and how they bottleneck tow- ers. Liquid outlets: choking in sidedraw

SAIChE IChemE SAIChE Board members: President: C Sheridan Imm. Past President D van Vuuren Honorary Treasurer L van Dyk + Vice President: Honorary Secretary: EMObwaka Vice President: D Lokhat Council member: JJ Scholtz Council member: AB Hlatshwayo Council member: K Harding Council Member: M Low Council Member: HMazema Council Member: MChetty Council Member: A de Bondt Council Member: MMabaso Council Member NN Coni Member (co-opted): MD Heydenrych Member (co-opted): MHughes Member (co-opted): CMausse Chair Gauteng: C Sandrock Chair KZN: D Lokhat Chair Western Cape: HMazema Contact details SAIChE PO Box 2125, North Riding, 2162 South Africa rundown lines and how it restricts tower capacity. Why must self-venting flow be assured in the presence of entrained vapour? Case Studies will be scattered throughout to illustrate the key principles and to distinguish good from bad practices. Delegates are also invited to bring along details of their applied distillation problems to share with others or one-on-one with Henry Kister. Course registration for the full three days includes Henry Kister’s textbooks and all course notes, teas, coffees, snacks and lunch. Please note that delegates are responsible for arranging their own accommodation. No provision for accommodation cost is made in the conference fee. All SAIChE IChemE members are eligible for a 10% discount, while companies sending more than 10 delegates will receive a 5% discount. courses@saiche.org.za

SAIChE IChemE member group news SAIChE IChemEWesternCape invited itsmembers to attend a talk byAnton Eberhard on ‘TheGlobal EnergyRevolution’, whichwas aSouthAfricanAcademyof EngineeringLecture. It was verywell attended by about 200 people. This very interesting and enlightening talk highlighted the importance of renewables and a distributed network. SAIChE IChemE KwaZulu-Natal members group held their AGMon the 30 November 2018. Theywould like toextend their thanks tomembers for their support andattendance. SAIChE IChemE is also very excited to announce that its SAIChE IChemE Congress 2020 will be held from July 1 to 3, 2020 at the University of the Witwatersrand in Johannesburg. To find out more about the event or the various structures of sponsoring the event, please contact the SAIChE IChemE office. saiche@mweb.co.za

Tel: +27 11 704 5915 Fax: +27 86 672 9430 email: saiche@mweb.co.za saiche@icheme.org website: www.saiche.co.za

December 2018 • MechChem Africa ¦ 7

Using pumps to generate electricity

A forward-thinking municipal technical team serving the requirements of the Drakenstein Municipality (Wellington) in the Western Cape has designed one of the country’s largest pump and turbine stations, which will be used for pumping water to the nearby town of Paarl during dry periods; and to generate electricity for the city during the remainder of the year.

D rakenstein Municipality’s city’s engineer for water operations, Hein Henning, says the city was faced with the dilemma of having topumpwatertoitsneighbouringtown,Paarl, for just one month a year. For the rest of the year the pump station would be dormant, while still needing hundreds of thousands of rands in maintenance to prevent corrosion, perishing,andlubricationandbearingdamage to the idle infrastructure. Instead, the progressive municipality chose an innovative solution that would meet the need, generate an income and simultaneously reduce the requirement for maintenance: By allowing the pumps to run backwards against thepressureofwater from its elevated Leliefontein reservoir, electricity for the region’s electrical grid could be gener- ated during times when the damwas full. Generating power The commissioning of the pump and turbine (PaT) station effectively brings online one of the largest such projects of its kind in South Africa.With all mechanical and electrical effi- ciencies taken into account, the station is able

to generate 57 kW from its three turbines, which, over the year, produces enoughenergy to power the entire region’swater infrastruc- tureof treatment plants, pumphouses, offices and related systems. “The water comes from the City of Cape Town’s Wemmershoek Dam and is gravity- fed to our city regions via our main reservoir. For one month of the year, during the dri- est month, the pumps are switched on to pump 400 ℓ /s upstream to Paarl to keep the Leliefontein reservoir full. As this is only nec- essary for that one month, the pumps would usually be switched off for the remaining eleven,” explains Henning. “However, the higher elevation of the reservoir allows us to rotate the pumps backwards to act as small turbines for the rest of the year, which generates electricity at more than an 80% efficiency. Unlike turbines however, the pumps are standard stock items fromthe supplier, KSBPumps andValves, and donot require specialised support and servic- ing. What’s more, they are durable enough to allow us to design the infrastructure with a 40-year lifespan. “With this long lifespan in mind, we de-

Electrical systems integrator, Brian Cooper at the main control HMI. Pump speeds are controlled via VSDs to prevent overspeed and to convert the electricity produced for compatibility with the city’s power grid. cided to make use of KSB pumps. We already have a number of these installed throughout our municipality and are aware of their reli- ability, as well as their long track record of support toourmunicipality, andothermunici- palities and water utilities throughout South Africa,” Henning adds. Upgraded pump station Before commissioning the project, the mu- nicipality had spelled out its requirement to replace its existing 96  ℓ /s pump station with a new one and had discussed the ability to generateelectricity in theoff seasonwithcon-

The Drakenstein Municipality’s Leliefontein pump and turbine station (PaT), which pumps water to Paarl for one dry month every year, while generating 57 kW of electricity by running the pumps as turbines, for the remaining 11 months.

8 ¦ MechChem Africa • December 2018

⎪ Pump systems, pipes, valves and seals ⎪

sulting engineers, Aurecon. Having designed andplanned a solution, themain contractwas awarded toHidro-Tech systems for mechani- cal and electrical work. Kiewiet Viljoen, projects director for Hidro-Tech systems, says the primary role of the project was to develop an efficient and reliable booster pump station to ensure uninterrupted water supply to nearby Paarl. Only once that need had been fullymet could the project managers consider its secondary role togeneratepower in theoff-peak season. “We knew, therefore, that we needed a technologically savvyand reliable servicepro- vider soapproachedKSBPumps andValves to procurethreeKSBETA200-40pumpstomeet and exceed the requirements of the tender. These not only perform brilliantly as pumps, but in turbine mode have a better than 80% efficiency, even after considering hydraulic and electrical losses. This speaks volumes for the overall efficiency and design of the pumps,” says Viljoen. Technology integration Electrical systems integrator, BrianCooper, of Hidro-Tech systems says despite the relative simplicity of the mechanical design, it does require complex integration of controls to deal with the hydraulic force and convert the electricity generated into a useable form. This required pump speeds to be controlled via a variable speed drive (VSD) to prevent overspeed and to convert thewave produced to a pure 50 Hz sine wave for compatibility with the city’s power grid. “The system is designed with full PLC control, which can be managed on site via a HumanMachine Interface (HMI) or accessed remotely via computer or a mobile device to giveoperators infinite control andmonitoring of the site wherever and whenever required. The industrial network also provides auto- mated control of the entire system including controls of the three pumps, valves, level indi- cators, flowmeters andother parameters that are critical to the system’s efficient operation, in either pump mode or water or electricity generation mode. “In addition to providing seamless control of the system, the control system ensures redundancy in all operating conditions and provides emergency measures in the event of failures in any part of the system, includ- ing valve controls, bypassing of the system or parameter changes as required to rectify any problems incurred,” he says. Solution provider KSB Pumps and Valves specialist, Stefano Testi, applauded theproject, saying its success paves the way for numerous similar projects throughout the Southern African region, wherever there is a reliable supply of water

Kiewiet Viljoen, projects director for Hidro-Tech systems and Drakenstein Municipality engineer for water operations, Hein Henning, at the KSB pump and turbine station (PaT).

KSB Pumps and Valves’ branches and dealers manager for South Africa, Francois Naude, with regional sales manager for sub-Sahara Africa, David Jones.

Project success Following the commissioning of the pump station and turbines, the system has begun operating at full capacity and theDrakenstein Municipality has started reaping the rewards of its forward-looking water management systems. “We are pleased with the outcome and commend everybody involved in the project for their innovation and dedication to build- ing a system that can be used as a blueprint by other municipalities around the country and across the globe. It has been a brilliant project with lots of challenges and innova- tion, with the end result being the delivery of a successful venture. We will definitely do similar projects with this team in future,” concludes Henning. q

at a high enough elevation to drive the PaT. “It is particularlyuseful inareas thatwould otherwise require the installation of pres- sure reducing valves to deal with water from high elevations. A PaT can fulfil the require- ment while generating electricity for nearby infrastructure or communities, especially rural ones. “Internationally, KSB is a leader in the supply of PaT solutions and we have a wide range of pumps that are suitable for this pur- pose.With growing pressure on the country’s powergeneratinginfrastructure,itpaysforlo- cal authorities, farmers and landowners with access towater to investigate the installation of PaT systems as cost effective and reliable sources of electricity that are not reliant on wind or sun to drive them,” Testi adds.

December 2018 • MechChem Africa ¦ 9

⎪ Pump systems, pipes, valves and seals ⎪

New levels of hydraulic efficiency in slurry applications

The Krebs slurryMAX™ range of slurry pumps from global minerals process specialist FLSmidth has brought new levels of hydraulic efficiency to Africa’s slurry operations.

Above: The Krebs slurryMAX-HD thickener underflow pump has extremely thick elastomer liners and a heavy-duty impeller, giving this pump extended wear life. Right: The Krebs slurryMAX XHP extra high-pressure pump has been added to the range to allow customers to design pumping systems with more stages and a higher final discharge pressure.

O ffered with a host of material options for liners and impellers, the Krebs slurryMAX range of pumps handles most plant applications across various industries. Its design is based on the success of FLSmidth’s millMax™ range of pumps, whose wear ring technology has created an efficient and long lasting slurry pump. The slurryMAX features an improved, more efficient, impeller and anoptional water drain plug for easier maintenance, allowing water that might have settled at the bottom of the pump to be quickly drained. In the slurryMAX 8×6 pump and larger units, a simple removable suction liner assem- bly allows for easy inspections of the internal components, aswell as the replacement of the impellerwithout removing thedischargepipe. In addition, the volute liner has an integrated back liner that bolts securely to the outer drive side casing. This makes for hands-free assembly, improving the safety aspects of the pump. Maintenance crews will also appreci- ate the easy-to-use lifting jig, for faster and safer rebuilds. Other models in the slurryMAX range include the XD version for aggressive appli- cations, which boasts thick elastomer liners and a heavy-duty impeller for extendedwear life. The slurryMAX HP is the high-pressure version of this model, and is designed for multistage high pressure pumping systems. Featuring a high-pressure outer casing, the slurryMAX HP uses all the same wear-

resistant parts as the XD, giving consistent performance and long life. Also in the range is the slurryMAX XHP, which enables customers to design pumping systems with more stages and a higher final discharge pressure. The XHP uses the same wear parts as its HD and XD counterparts, but with an even more robust outer casing

than the HP version. Predictable and even wear life across all wet-end parts is among the benefits of the slurryMAX pump, as are its heavy-duty shaft and taper roller bearings that cannot be over greased, enabling the long-lasting bearings to be rated for a minimum of 100 000 hours. q

Cast off with Victoria butterfly valves Valve manufacturer GEMÜ has obtained anotherapprovalforitsGEMÜ480Victoria butterfly valves. In addition to being ap- proved for drinking water and gas, this se- ries will, from now on, also have a shipping approval inaccordancewithDNV-GL.With this certification, it is possible to use the GEMÜ valves for the isolation and control of non-flammable gases, seawater, water, air andoil in ships that require classification andbuilding regulations inaccordancewith DNV-GL, guaranteeing compliance with applicable regulatory codes and standards for maritime applications and adhering to the highest quality guidelines. valves in the GEMÜ 480 Victoria se- ries into reliable components for demanding appli- cations. Thanks to the epoxy coating of at least 250μm– inaccordance with the corrosiveness category C5-M as per DIN EN ISO 12944 – they are resistant to seawater and can withstand highly cor- rosive loads caused by condensation and contamination.

Systemsthatareusedinshippingarenot only subjected to extreme climatic condi- tions and a harsh environment, but they must alsowork faultlessly under extremely highmechanical loads. High corrosion pro- tection and the triple seal contour of the shaft seal have already made the butterfly

Depending on the product type, DNV-GL- approved GEMÜ 480 Victoria butterfly valves are available withmanual, pneumatic or motorised actuators. q

December 2018 • MechChem Africa ¦ 11

Engineered for use at the most aggressive duties,Warman ® Mill Circuit pumps easily manage large particles in highly abrasive slurries.The pumps are designed for severe slurry applications such as ball and SAG mill discharge, cyclone feed as well as water-flush crushing in minerals processing plants. Mill circuit pumps reduce operating costs

Marnus Koorts.

W eirMineralsAfrica showcased its flagship mill circuit pump, the Warman ® MCR ® 450 at Electra Mining Africa 2018. Marnus Koorts, product manager for slurrypumps atWeirMineralsAfrica, pointed out on display the massive 1.5 m diameter 450, saying: “Like all pumps in the Warman MCR range, this 13 ton slurry handling ma- chine is designed to increase productivity and decrease downtime, compared to older gen- erationWeir andother pumps in the industry.” Koorts says Warman Mill Circuit pumps are based on80 years of fundamental and ap- plied research, backed by wear performance field trials. “Mill circuit applications are among the toughest in a minerals processing plant, and Warman MCR pumps incorporate the latest in hypereutectic alloy and elastomer technol- ogy,” he says, adding that this significantly extends the wear life of the pump in highly abrasive and corrosive slurries, reducing operational costs.

Warman MCR with elastomer liners installed at several gold and copper mines.

Pontoon solution at Madagascar mine Regular engagement with Rio Tinto’s QIT Madagascar Minerals (QMM) operation and a good understanding of local conditions has allowedWeir Minerals Africa to provide the optimal solution to a customer’s recurring challenge on a process pond. A ccording toWeirMineralsAfrica’s dewatering product specialist, Neil Matthews, a mine in Mada- gascar was experiencing con- graphic and site conditions, as well as local fauna and flora.”

To provide the most suitable Weir Minerals products and solutions, the team specifiedaWarmanAH10/8pumpmounted on a Multiflo ® pontoon with the pump coupled to a variable frequency drive (VFD) to enable greater flexibility in dealing with varying site conditions. A second pontoon was fittedwith aWarmanAH6/4pumpwith a motor and fixed-speed drive, because its operating conditionswould remain constant throughout the life of mine. Both pontoons are connected to a float- ing docking station, which, in turn, is con- nected to a 20 m walkway fixed to the bank-side landing.

tinual collapse of the 20 m suction hose to theWarman ® AH ® 12/10 pumpmounted on a skidat thebackof thepond. This resulted in the need to keep priming the pump, causing regular downtime. “Unpacking the issues facing the custom- er was the first part of upgrading the mine’s process water utilisation,” says Matthews. “We discussed several options with the customer, after which our dewatering and engineering teams collaborated closely to design a solution. It was vital to consider the problem carefully in the context of geo-

Having the Warman slurry pump mounted on the skid at 30° to submerge the suction eye of the impeller solved the customer’s continually collapsing suction hose problem.

12 ¦ MechChem Africa • December 2018

⎪ Pump systems, pipes, valves and seals ⎪

“It is standard practice in most of our pontoon designs to mount the pump sets at 30° to submerge the suction eye of the im- peller, thereby ensuring consistent priming,” Matthews says. Oneof themost important factors affect- ing the solution was Madagascar’s weather conditions, which include regular tropical storms andhighwind speeds. Thesehave the effect of creatingwave actionandwind load- ing on the pond, which the pontoon solution has to accommodate. To address the wave action and mini- mise possible structural damage, the fixed walkway was designed to incorporate a pivot systemon the bank landing structure. This allows the entire assembly, including the docking station, to rotate 90° and still be tied down to the shore during these storms. “Madagascar is also known for its var- ied wildlife, including crocodiles,” says Matthews. These creatures tend to climb onto the deck to bask in the sun, making it almost impossible for staff to conduct rou- The high resilience rubber wear liner enables the handling of coarse particles and ball scats with ease, while its lightweight design relative to other pumps in its category facilitates safer handling. These liners also come in at a lower cost than traditional heavy metal liners. Importantly, different material combina- tions are available to ensure that customers get a fit-for-application pump capable of pro- viding reliable performance cost effectively, tailored to their site conditions. The Warman MCR pump has a large di- ameter, low speed, high efficiency impeller. Koorts explains that this canbemanufactured from a range of abrasion resistant alloys, al- lowing the most appropriate material to be selectedforthecustomerapplication.Thiswill increase wear life and reduce operating costs whencomparedtootherpumpsinitscategory. Reduced recirculation is achieved by the deep expelling vanes on the front of the high-chrome impellers. Expelling vane tip tur- bulence is minimised by the patented shroud feature that traps tip vortices and prevents localised scouring on the throatbush face. This, again, extends wear life and reduces maintenance. The split outer casing on the Warman MCR pump provides structural integrity and high operating pressure capability, ease of maintenance and safety. This feature also allows internal liners to be fully worn before replacement. Warman throatbushes feature pre-swirl vanes, which offer optimum reliability and

The split outer casing on the Warman MCR pump provides structural integrity and high operating pressure capability, ease of maintenance and safety.

tinemaintenance.Restrictingthisaccesswas achieved by closing all the gaps between the handrails and the separate structures. “Our design took all the site conditions into account, making for better and more predictable operational reliability,” he adds. “Both the pontoons and the pumps can now be easilymoved for servicing or for securing during bad weather.” wear life. There is a patent pending on this innovative throatbush design, which was developed to improve impeller eye wear life and reduce the wear caused by recirculation at the impeller/throatbush interface. This has been accomplished by a series of guide vanes in the pump inlet, which induce a rotational velocity in the slurry. An adjustable stuffing box allows for the centering of the stuffing box and lantern restrictor to the shaft sleeve. This increases packing life and decreases gland seal water

Weir Minerals Africa’s experience with mounting pump sets onto pontoons and its extensiveprocess-relatedknowledgeplayed a significant role in developing the product offering for the customer. “Itwas also important for thedesignengi- neers to be present during the commission- ing process to ensure support,” Matthews concludes. q “Our Warman Mill Circuit pumps are engineered to offer the most cost effective solution across a range of applications, and with installations on many leading mine sites across the globe it is proven to be themill cir- cuit pump of choice for the hard rock mining industry,” Koorts concludes. q consumption. Another new design feature is the single-point gland adjustment, which facilitates safe packing adjustment outside of the stuffing box guard while the pump is operating.

One of the two Multiflo ® pontoons installed at a mine in Madagascar, which consist of Warman AH pumps coupled to variable frequency drives (VFDs).

December 2018 • MechChem Africa ¦ 13

On Thursday, 25 October 2018, South African President Cyril Ramaphosa officially opened Gibela’s train manufacturing plant in Dunnottar, east of Gauteng. MechChem Africa talks to systems integrator, David Blackwood of DESign about the modern systems installed to ensure high integrity fabrication. Mega train manufacturing ramps up in Dunnottar

G ibela’s flagship Dunnottar train manufacturingplantinEkurhuleni, Gauteng, was officially opened by Cyril Ramaphosa last month. The first of its kind on the continent, over the next 10 years, this facility will construct 580 Alstom X’Trapolis Mega commuter trains. The X’trapolis Mega is designed to be compatible with South Africa’s Cape gauge and, by virtue of its light-weight stainless steel construction and the use of modern inverter-based drives with regenerative braking, is 31% more energy efficient than its predecessors. Gibela’s 53 000 m 2 green field plant is spreadover a 78ha site andwas built at a cost of R1-billion. Its manufacturing workshops, covering33000m 2 , aredesigned inamodular format to facilitate lean manufacturing and, at peak production by the end of 2020, two cars a day, one and a half trains a week and 62 trains a year will be produced.

Attheofficialopening,GibelaCEO,Thierry Darthout, said that theworld-class plant fea- tures advanced manufacturing innovations involving 250 linked industrial activities and the assembly of at least 10000parts. Notable innovations include: • Adrawbench for shaping 5.0mmstainless steel that can pull 22 m long side sill pro- files and fabricate roof corrugations and various stiffeners for the train. • Seven-axis Yaskawa MOTOMAN robotic welding systems installed to work in oth- erwise hard-to-reach welding places. • Mechanical andelectrical rotatingfixtures for improved ergonomics and increased speed. • A scissor lift table to replace overhead cranes, eliminating safety risks during installation while increasing efficiency and accuracy. “We are immensely proud of what we have achieved and we commit to delivering trains

to PRASA that will both improve the lives of South Africans and provide a valuable plat- form for South Africa’s industrial rebirth,” said Darthout in the presence of President Ramaphosa. The car body shell assembly area David Blackwood of DESign, the systems in- tegrator forGibela’s car body shell workshop, says that the constructionof a trainbody shell is not dissimilar to that of amotorcar. “A train body structure ismade up of an under-frame, body-sides or sidewalls, a roof, end-frames and closures such as windows and doors. “Whatwe do is to design andmanufacture the tooling jigs and the infrastructure to allow OEMs to produce the sub-assemblies and build these into completed rail or car bodies. The under-frame, for example, ismade up of a front, centre and rear floor, which are manu- factured in smaller jigs and welded together before being loaded into the under-body complete jig. Once welded, the floor gets moved into the main framing line, where the complete sidewalls and roof –whichwill have also been welded as sub-assemblies in their own purpose built jigs – are loaded, clamped and accurately positioned to give the final geometry. “Inbroad terms, we are responsible for the infrastructure that puts the sheet metal shell of the passenger trains together for Gibela and we provide the tooling, technology and the infrastructure todo that,” Blackwood tells MechChem Africa . Describing a typical sub-assembly area, he says that components welded in the body shell workshop area of the plant are typically loaded into jigs and manually spot- or MIG- welded by station operators. “Gibela chose resistance spot welding guns from Nash in India for the plant, based on their successful use in Alstom’s Sri City plant in India as well as the Lapa plant in Brazil,” says Blackwood. “In Gibela’s body shell main sub-assembly area, there is an under-frame, sidewall, end- frame, roof and letter-board welding assem- bly area, which, from a welding perspective, relies on manual and robot spot welding for the assembly. “The main framing lines, called cathedrals

The Cathedral or main framing line at the flagship Gibela Dunnottar train-manufacturing plant, where the under-body, end-frames, roof and sidewalls are loaded together and framed to complete the shell.

14 ¦ MechChem Africa • December 2018