To sestrain the generation of NOx by adding steam obtained from an evaporative cooling system to intake air and humidifying it, and supplying a gas engine with such air as having humidity of the level of summerseason even in winterseason.
A humidifier 7 is installed in the middle of an inlet pipe 2, and a three way valve 5 in the middle of a steam exhaust pipe 4, respectively and this three way valve 5 and the humidifier 7 are interconnected to each other by a humidify steam pipe 6. Steam being exhausted out of the exhaust pipe 4 is produced when cooling water in a cooling water jacket is heated, and it flows into the humidifier 7 by way of the three way value 5. In addition, a NOx sensor 8 is installed in the middle of the exhaust pipe 2, and a signal of NOx density obtained by this sensor 8 is received by a control unit 9, then steam quantity to be added to the humidifier 7 and valve opening of the three way valve 5 are operated by a control unit 9, emitting a command. With this constitution, even if humidity in the atmosphere is varied by seasons, steam to be secured by an evaporative cooling system is added to intake air to humidify it, whereby the generation of NOx is restrained.
IKEDA KATSUMI
TSUKITA NOBUAKI
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