Combustion system having multistage burners arranged to mix air and fuel based on fuel property and engine load

Abstract

A combustion system for a gas turbine engine includes a first, second and third burner stages 7011, 7012, 7013, where the first, second, and third burner stages are radially and axially spaced apart from one another. A fuel delivery subsystem conveys a fuel blend of a first fuel (e.g. natural gas) and a second fuel (e.g. hydrogen) to one or more of the first, second and third burner stages based on a load condition of the gas turbine engine. Each burner stage comprises a hybrid mixer 804 including a first mixing stage 806 for premixed combustion and a second mixing stage 808 for diffusion combustion. A sensor generates a signal indicative of a thermochemical property of the fuel blend. A controller responsive to the signal controls a metering valve to convey a first portion of the fuel blend to the first mixing stage and a second portion of the fuel blend to the second mixing stage based on the thermochemical property of the fuel blend. The system offers superior engine operability (e.g., inhibiting NOx and CO emissions and thermoacoustic instabilities) by distributing heat release axially and radially within the combustion system. Fig. 8