GFS 0039 Open Cycle Gas Turbine Project Rev 0

8/8/2019 GFS 0039 Open Cycle Gas Turbine Project Rev 0

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OPEN CYCLE GAS TURBINE

What is an Open Cycle Gas Turbine (OCGT)

An open cycle gas turbine is a combustion turbine plant fired by liquid fuel to turn agenerator rotor that produces electricity. The residual heat is exhausted toatmosphere at about 550 degrees Celsius. This technology is similar in design tothe combustion turbines, or jet engines, used in the aviation industry.

The turbine and generators are housed in enclosures designed to reduce noiselevels and occupy an area of approximately 75m X 25m per unit. The exhaust stackheight is approximately 30m with the height of the intake structure being 20m.

How does an OCGT work

A compressor sucks air in from the atmosphere and compresses it through a numberof compressor stages. Fuel is pumped into a combustion chamber and mixed withthe compressed air. The fuel/air mixture is then ignited to form hot, high velocitygas. This gas is passed through turbine blades that turn the shaft that is attached tothe rotor of the generator. The rotor turns inside the stator and electricity isgenerated. This electricity is then distributed via the high voltage network to where itis needed.

Eskoms OCGT Project:

Due to the growth in the South African economy, which results in an increaseddemand for electricity, Eskoms excess electricity generation capacity is beingdepleted, especially when it comes to supplying electricity during peak demandperiods. When government gave Eskom the green light to build new power stationsin October 2004, work started in earnest to determine the kind of peaking plant thatcan be built in a relatively short time, given that it became clear that Eskom wouldneed additional capacity to meet the demand during the winter of 2007.

Generator

Fuel

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Based on the following considerations, it was decided to build two OCGT plants:

The technology has been proven all over the world and has a good track record.

There are numerous suppliers across the world.

Open Cycle Gas stations can be built in 3 to 4 years, and can be fast tracked,resulting in even shorter project lead times.

The proposed OCGT gas turbine stations will add approximately 1000MW of newgeneration capacity, and the plan is to have the two stations operational by thewinter of 2007. It is estimated that an open cycle gas turbines life span is 25 years.

Proposed Plant Locations

Seven potential locations for the two OCGT stations were identified in the WesternCape, with the preferred locations being in the Atlantis Industrial Area and next tothe PetroSA fuel manufacturing facility in Mossel Bay. There are numerousadvantages to the chosen sites such as existing infrastructure resulting in less timeand money required for site development, and relatively easy access to liquid fuel.The sites are strategically placed to make use of the opportunity to use gas asprimary energy source should natural gas become available in future.

The Proposed Atlantis Plant Location

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The Atlantis OCGT station will receive its liquid fuel (kerosene or diesel) from one ofthe major fuel suppliers either via road, rail or pipeline, with road being the preferredoption. The Atlantis plant will consist of 3 to 5 units, depending on the manufacturerselected, and will generate approximately 600MW.

Integration of the power station into the transmission network will be via 4 x 400kVlines in to the existing Aurora Koeberg 400kV lines. This will require the building ofa maximum 10 kilometres of line.

The Proposed Mossel Bay Plant Location

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PetroSA Site


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The Mossel Bay OCGT station will receive its fuel from the PetroSA facilities. Theplant will use liquid fuel and will consist of 3 or 4 units, depending on themanufacturer selected, generating approximately 450MW.

Integration of the power station into the transmission network will be via 2 x 400kVlines into the Proteus substation. This will require the building of approximately 30km of line.

Produced by: Generation CommunicationGFS 0039 Revision 0 (September 2005)

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GFS 0039 Open Cycle Gas Turbine Project Rev 0