Wärtsilä, ABB and Foster Wheeler
The Sasol gas engine power plant (GEPP) is the largest natural gas-fired power plant in Africa and the first gas based power plant in South Africa.
The 140MW plant is located at Sasolburg, South Africa. It was commissioned in December 2012 and has been fully operational from July 2013.
The power plant is expected to provide power for the under construction Sasol Wax expansion project and the ethylene purification unit five.
Sasol New Energy, a subsidiary of Sasol, owns the $181m plant. It is the largest single investment in gas technology in Africa. Wärtsilä was the turnkey contractor for the project.
The Sasol GEPP aims to reduce greenhouse gas emissions of approximately one million tonnes per annum, by employing a cleaner fossil fuel-based technology than coal-based technology. It also aims at reducing the NO2, sulphur oxide and particulate emissions.
The project created 500 jobs during construction stage and 44 full-time jobs in operational stage.
Sasol gas engine power plant make-up
The power house of Sasol GEPP is divided into three sections. Each section contains six engines, interconnected to a medium-voltage room. The radiators are placed on the roof for improved cooling. The high-voltage equipment required for the plant is located in a separate building.
The gas feedstock for the Sasol power plant is supplied by the central processing facility (CPF) in Mozambique. The CPF is owned by Sasol Petroleum International, a subsidiary of Sasol.
The Sasol chemical factory adjacent to the Sasol GEPP, will utilise half of the electricity generated, while the remaining half will be transferred to the national grid.
Sasol power plant construction
The Sasol gas-fired power plant construction and commissioning took 15 months to complete. The site works commenced in September 2011, and the shipment of equipment and installation took nine months.
The engines and grid synchronisation were started for the first time in November 2012.
Wärtsilä 20V 34SG engines at Sasol gas-fired power plant
Sasolburg gas-fired power plant is installed with 18 Wärtsilä 20V 34SG generating sets, which run on natural gas. The 34SG engine contains a microprocessor-based distribution system for controlling the engine functions.
The main control module of the engine control system keeps the engine at optimum performance in all operating conditions and helps in maintaining the gas quality.
The 34SG engine is equipped with an open-interface cooling system with four cooling circuits. It helps in optimal cooling and heat recovery, and also enables the plant to operate with minimal water requirement.
Contractors involved with Sasol power plant
The engineering, procurement and construction (EPC) contract for the Sasol GEPP was awarded to Wärtsilä. The contractual scope included engineering, civil works and building construction, and supply of all the equipment. Wärtsilä also undertook the electrical and mechanical installation works. Wärtsilä is responsible for the operations and maintenance of the power plant, under a three-year agreement.
Foster Wheeler was awarded the contract to conduct the feasibility study of the plant. It was also awarded the management services contract for the outside battery limit portion of the generating plant.
The scope of the contract included the earthworks for the entire outside battery limit site, an access road, and utility connections. The contract also included setting up of an 88kV sub-station, 15/88kV step-up transformers with associated electrical infrastructure and a network system.
ABB had the contract for providing a 145kV double busbar gas-insulated switchgear system for the plant. The company was responsible for the design, supply, installation and commissioning of the switchgear alongside SCADA protection and control.
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