Development of a Dual Fuel LBTU Gas/Diesel Burning Combustion System for a 4.2 MW Gas Turbine
This paper describes the design and development of a gas turbine combustion system (combustion chamber and dual fuel injector) that is capable of burning a gasifier generated low heating value (LBTU) gas as well as a conventional gas turbine (diesel) fuel. The system will be installed in a 4.2 MW gas turbine and forms part of a 15 MW integrated gasification combined cycle heat and power generation technology demonstrator plant in Sweden. The combustion system design features a conventional combustor air distribution and aerodynamic pattern, discrete coaxial jets air blast liquid fuel atomisation and a combination of swirl and plain orifice LBTU gas fuel injection with a passive air purge arrangement. Rig tests were carried out at operating pressures of up to 7 bar simulating various engine operating points using LBTU gas and diesel fuel. The results showed that the emissions, exhaust temperature distribution and combustor metal temperature were in line with the program objectives. The lean flame stability margin using LBTU gas was more than adequate in relation to load change and fuel changeover requirements.