Wide range gaseous fuel combustion system for gas turbine engines

Abstract

Systems capable of supplying either all gaseous fuel, all liquid fuel, or a mixture of the two, at a preselected ratio have been successfully employed in gas turbine engines. The mixing of such fuels has taken place in the combustion chamber and has caused the nozzle design and system controls to complicate the structure and increase costs. The subject system for burning gaseous fuels having a range of calorific values has overcome these problems by providing a simple inexpensive system. The system uses a starting step where only high calorific value gaseous fuel is injected through a first fuel supply passage of an injector and operates the engine to a preestablished engine operating parameter. After the preestablished engine operating parameter has been reached a low calorific value gaseous fuel is mixed in a mixing chamber outside the combustion chamber and injected through the first fuel supply passage until a level of heating value of the mixed fuel or a second engine operating parameter has been reached. The mixing continues and a second fuel supply passage of the injector is opened to increase the mass/volume flow of fuel into the engine. The ratio of low calorific value gaseous fuel increases and the high calorific value gaseous fuel decreases as the engine operating parameters are monitored until the engine operates on only the low calorific value gaseous fuel.