Air-fuel ratio correction control method and apparatus for premixed gas engine

摘要

PROBLEM TO BE SOLVED: To provide an air-fuel ratio correction control method for controlling the air-fuel ratio so as to stably operate a gas engine even in a case of biogas in which the properties of fuel gas are changed with time.SOLUTION: There is provided the air-fuel ratio correction control method of a pre-mixing type gas engine 100, in which mixed gas M with fuel gas F and air A being mixed therein is supplied. The air-fuel ratio correction control method includes: a step of measuring the temperature of exhaust gas E to be exhausted from a combustion chamber 2 of a gas engine 1; a step of setting the air-fuel ratio on the basis of the temperature of the exhaust gas E so that the air-fuel ratio may be increased compared with the value before exceeding the upper limit if the temperature of the exhaust gas E exceeds the upper limit of the preset adequate range, and that the air-fuel ratio may be decreased compared with the value before being below the lower limit if the temperature of the exhaust gas is below the lower limit of the adequate range; and a step of adjusting the supply of fuel gas F or air A according to the present set value of the air-fuel ratio.