Combustion Gas Turbines - The Combustion Chamber PDF Print E-mail
Written by Norrie   
Wednesday, 13 January 2010 10:12
Article Index
Combustion Gas Turbines
Principles and Operation
The Air Compressor
The Combustion Chamber
The Compressor (HP) Turbine
The Variable-Angle Nozzles Load Turbine
Turbine/Compressor Lube Control Oil System
Turbine Hydraulic Oil Trip System
Turbine Overspeed Trip Mechanisms
Turbine System Details
All Pages

2. THE COMBUSTION CHAMBER

The compressed air from the axial flow compressor is piped to the combustion chamber. The turbine we are discussing has Six (6) identical combustion chambers - three on each side. Each chamber consists of the following: -

1. The Fuel Burner. - Using Natural gas, no atomiser is required - the fuel however must have all liquid knocked out.
2. Swirl Vanes. - These are installed at the point of fuel injection in order to get thorough mixing of the fuel and Primary Air, (air for the combustion - 15 to 20% of the compressor discharge). This is done to prevent Hot-Gas Pockets in the hot-gas path to protect the metal of the turbine from excessive heat.
3. The Burner Basket - This is fitted around the burner and contains holes through which the Secondary Air (about 30% of the air), passes into the burning gases to ensure complete combustion of the fuel.
4. The Igniters. - Spark plugs are used for the initial ignition of the fuel/air mixture. The hot gases from the combustor mix with the remaining air from the compressor (about 50%). This is called ' Tertiary Air ' and cools the gases to a safe turbine inlet temperature - at about 1700 °F. The hot, expanding gases pass into a ' Transition Piece ' which ensures the final mixing of the gases. The hot gases now pass to the six - fixed nozzle guide-vanes which direct the gas flow through the turbine assembly. Between the combustion chambers, 'Cross-fire' tubes are installed to ensure combustion in all chambers. (A flame detector system exists which will instantly shut down the fuel supply and therefore the turbine, should a flame failure occur in a chamber). (See Figure: 18)


Figure. 18



Last Updated on Wednesday, 24 February 2010 20:06