CONTROLLING METHOD FOR BOILER DISCHARGED GAS MIXING DEVICE

摘要

PURPOSE:To make a proper control of an amount of mixed discharged gas into a combustion air in response to a boiler load variation by a method wherein an adjusting damper control circuit controlled in response to a load instruction is operated such that a detected concentration value of oxygen after mixing of the discharged gas is fed back and controlled. CONSTITUTION:An instruction issued from a function generator 14' in response to a load instruction 13 is inputted to an electric motor 9 and a rotation of a gas mixing fan 11 is controlled. In turn, a detected concentration of oxygen value 15' detecting an oxygen concentration of combustion air 19 after mixing the discharged gas with an oxygen concentration meter 15 is inputted to a subtractor 16 in the flow rate adjusting damper control circuit 21 having an instruction generated from the function generator 14 in response to the load instruction 13 through a primary delay circuit 17. It is compared with an input value from the function generator 14 at the subtractor 16 and calculated and then a degree of opening of a flow rate adjusting damper 8 is adjusted in such a way as its difference becomes zero. An error caused by a delay in responding in a fluid coupler 10 is fed back as a variation of the oxygen concentration, a degree of opening of the flow rate adjusting damper 8 is adjusted and then a generation of the nitrogen oxide is also restricted.