CONTROLLING DEVICE FOR MULTI-STAGE INCINERATOR

摘要

PURPOSE:To reduce a volume of waste gas exhausted to the surrounding air by a method wherein the oxygen concn. in the waste gas is detected and the volume of combustion air is controlled in a multi-stage incinerator of combustion gas circulation type for burning the organic sludge contained in the sewage. CONSTITUTION:Oxygen concn. O2 contained in the waste gas from an incinerator 1 is detected by a densitometer 23. Calculation circuit for air-fuel ratio 30 calculates the air-fuel ratio control signal alpha in which the concn. of O2 contained in the waste gas is set to a desired value. In the combustion air calculation circuit 29, a desired air volume A0 is calculated in reference to the air-fuel ratio control signal alpha and then input to a controller 28. The controller 28 controls the degree of opening of a damper 8 in response to a difference between the actual air flow rate value A1 detected by a flow meter 9 and the desired value A0 so as to control the volume of air supplied to the burner 3 and the incinerator 1. In this way, the oxygen concn. contained in the waste gas is made constant thereby an incomplete combustion may be prevented and at the same time a volume of supplied air i.e. a volume of waste gas may be reduced.