Evaluation of synthetic fuel character effects on a rich-lean gas turbine combustor

Rich-lean combustion systems are a new generic class of stationary gas turbine combustors capable of low NO /SUB x/ emissions performance with fuels containing high concentrations of nitrogen. Several rich-lean combustor designs are currently under development by utility gas turbine manufacturers as part of the ongoing DOE/NASA Low NO /SUB x/ Heavy Fuel Combustor Concepts Program. The rich-lean combustor concept is similar to the fuel-staging technique used in boiler combustion systems for controlling NO /SUB x/ emissions from fuels containing high fuel-nitrogen. Briefly, a small amount of primary air is mixed with the fuel in the head-end of a rich-lean combustor. This creates a fuel-rich combustion zone to release nitrogen from fuels containing nitrogen compounds and maximize the early formation of molecular nitrogen. This richburn step is followed by the rapid introduction of secondary air to achieve complete combustion of unburned hydrocarbons and carbon monoxide under fuel-lean conditions to minimize the formation of thermal NO /SUB x/. The combustion is optimized in the rich stage to minimize the formation of NO /SUB x/ and molecules such as NH/sub 3/ and HCN which would convert readily to NO /SUB x/ in the lean stage. Sufficient residence time in the lean stagemore » assures complete combustion of even poor quality fuels.« less