STEAM TEMPERATURE CONTROL DEVICE FOR ONCE-THROUGH BOILER

摘要

PROBLEM TO BE SOLVED: To provide a steam temperature control device for an once-through boiler capable of properly correcting a feedwater-fuel ratio even when imbalance of feedwater-fuel ratio or imbalance of thermal load is found.;SOLUTION: This steam temperature control device for the once-through boiler, comprising a means for controlling a steam temperature at a superheater outlet by injecting the fluid extracted from a fuel economizer outlet to an attemperator mounted on the superheater outlet, and a means for controlling a main steam temperature to a prescribed value by correcting main steam temperature control bias calculated by PI control based on injection quantity and the feedwater-fuel ratio, on the basis of an evaporator outlet superheat degree correction value, further comprises a means for calculating a ceiling wall outlet saturation temperature restriction correction value to further correct the main steam temperature control bias on the basis of the correction value, and a means for determining a ratio of fluid flow rate and fuel quantity passing through a furnace, and performing bias reducing operation to the feedwater-fuel ratio when the fuel is excessively supplied.;COPYRIGHT: (C)2006,JPO&NCIPI