Low emission combustion process and apparatus

Abstract

A process for forming low-emission combustion gases. A lean mixture of fuel and air provides a substantially homogeneous mixture within the combustion zone. The fuel is preferably vaporized and, alternatively, may be introduced into the burner as microscopic droplets. Combustion temperature is maintained below about 3,000.degree. F. to reduce nitrogen oxides and combustion is conducted under stable conditions which sufficiently exceed lean blowout to reduce formation of carbon monoxide and unburned hydrocarbons. The flow velocity into the burner is higher than the turbulent flame velocity. A dilution zone may be provided downstream from the combustion zone. To control performance, input air may be split into a first stream to the combustion zone and a second stream to the dilution zone. A quantity of water may be admixed with the fuel and be prevaporized to form water vapor containing fuel droplets. A method of operating a gas turbine with a burner operated as above, generating combustion gases to the turbine. A burner for producting low emission exhaust gases. The burner has a combustion zone and a dilution zone with means to split air input into a first stream to the combustion zone and a second stream to the dilution zone. The combination of a burner and a gas turbine with the burner having a combustion zone and a dilution zone. Diversion means vary the fuel-to-air ratio in the combustion zone by diverting air to the dilution zone to produce low emission exhaust gases to drive the turbine.