The South African-based Zest WEG Group is drawing on its wide range of in-house technology and products to design and supply a complete turnkey diesel power generation facility for Syrah Resources’ Balama graphite project in northern Mozambique.
The substantial Balama plant – measuring 185 m long and 54 m wide – is the largest single footprint power plant tackled by subsidiary Zest Energy, and is expected to begin a gradual ramp-up of power production from the first quarter of 2017.
Given its remote location some 260 km west of the port town of Pemba, the Balama project will use the uninterrupted power produced by the continuous generation facility to cater for the full plant demand, according to Alastair Gerrard, MD of Zest Energy.
“While the mine will have access to power from the national grid, it was essential that the equipment selected for the power plant would provide high levels of power supply reliability and availability, while also requiring as little manual operation and maintenance as possible,” says Gerrard
The Zest WEG Group, a subsidiary of WEG Brazil, is well known for its large range of WEG electric motors, switchgear and variable speed drives. The group also supplies motor control centres, generator sets and integrated energy solutions, and has three fully fledged manufacturing facilities in South Africa.
“The design took into account the high availability requirements by incorporating an ‘N+1’ format into the plant,” Gerrard says. “In terms of the current scope of supply, the plant will begin approximate production of 12.5 MW with seven 2 200 kW diesel generators – six of which will run continuously while one will be on standby to allow for maintenance and repairs.”
“To monitor and control the plant, Zest WEG Group company, Shaw Controls, designed and manufactured an E-House, with a medium voltage switchboard incorporating a control system to synchronise and monitor the engines,” Gerrard says. “The E-House also includes a control room, complete with an overall power plant control system with built in supervisory control and data acquisition (SCADA) functionality – giving the plant operator full control from a central point.”
To feed the generators, the client will provide a bulk fuel storage system to which Zest WEG Group will link its own 30 000 litre intermediate fuel tank – with a fuel duplex fi ltration and circulation system as well as all interconnecting piping, valves, pumps and fittings within the power plant area.
David Claassen, executive Integrated Solution Centre at Zest WEG Group, says all main aspects of the project – from the generator sets to the E-House and the plant auxiliary electrical equipment – are sourced and produced in-house.
“The benefit for our client is that they have a single point of contact with us; and we have the necessary control over the design and manufacture to ensure the quality and suitability to client requirements,” says Claassen. “Providing these kinds of solutions limiting the need for third party contractors also makes us cost competitive, as there are various shared resources within the group through which we leverage value.”
Dealing with conductive dust
In addition to the remoteness of the site, Balama posed a particular challenge on the electrical front – highly conductive graphite dust.
“Not only is the dust generatedby graphite mining able to conduct electricity between terminals on electrical equipment, but the shape of the dust flake allows it to pack densely around any point or surface on which it settles,” Gerrard says. “This means that all electrical equipment must be designed to minimise the potential ingress of graphite dust, and we could not permit any open-to-air electrical connections.”
Consequently, an entire custom designed air filtration system was developed to control the quality of the air passing through the generators. This had to accommodate the substantial air flows needed to keep the 20 cylinder diesel engines aspirated, as well as for cooling the generator sets. The system was also designed to be self cleaning, which aids in the reduction of maintenance interventions.
“To ensure complete insulation, terminations on all equipment – including alternators as well as medium voltage and low voltage items – were all insulated before they left the respective Zest WEG Group factories,” Gerrard says.
Further to this, the filtration and cooling systems themselves required a large number of electric motors to drive their onboard fans, and Zest WEG Group was able to supply these to exacting specifications.
“In addition to Balama’s power facility, we are very pleased that our Group company EnI Electrical was recently awarded the contract for the complete electrical installation of the mining infrastructure and the process plant – as well as handling the instrumentation and control requirements,” says Claassen. “EnI has already begun some early works on site relating to the earthing design and earthing mat.”
With a target date for completion set for second quarter 2017, Zest WEG Group companies will see a steady build-up of personnel on site in the coming months. “Our experience in planning and executing contracts in African countries is substantial, as we have worked in probably 90% of them over the years,” Claassen says.
“This requires complying with local labour and other regulations, so our familiarity with these compliance issues allows us to hit the ground running, ensuring that our activities are streamlined and productive.”
Zest WEG Group’s recent work in Mozambique includes the complete electrical construction of the Beira port, and a host of electrical projects in industrial developments.
“Our experience in southern, west and east Africa is especially advantageous to clients who are based on other continents, and who value the presence of a partner who appreciates the conditions and remains close to the project after commissioning,” he says.
Claassen highlights the importance of language issues in facilitating safe and compliant operations; Zest WEG Group’s dedicated Africa team includes specialists who are fluent in both Portuguese and French so that clients receive technical documentation, site signage, operating manuals, datasheets and any other material in the locally required languages.
“These and other added-value elements, such as our project management and procurement services across the group and across the globe, are among the ways we mitigate risk for the client and ensure cost efficient implementation,” he says.