CONTROLLING METHOD FOR STEAM TEMPERATURE OF COAL FIRED ONCEETHROUGH BOILER

摘要

PURPOSE:To control the variation of the steam temperature of a coal fired once- through boiler by a method wherein the change of quality of coal is detected from the oxygen remaining in the combustion gas, and the ratio of fuel to feed water in the boiler control system is corrected. CONSTITUTION:A feed water amount control 2 and a fuel amount control 3 are simultaneously controlled by a load demand signal 1, and the fuel amount is corrected by a steam temperature control 5 through a steam temperature correcting apparatus 4 so that the steam temperature is kept constant. In such a controlling system, the calorific variation of coal is detected by a combustion gas O2 detector 8, and its output and the signal from a setting device 9 are compared with each other in a comparator 7. When the combustion gas O2 has deviation, the fuel amount is corrected by an integrating controller 6 to control the variation of the steam temperature.