WATER FEED METHOD IN OPERATION FOR CONTROLLING THE NUMBER OF SHELL AND TUBE TYPE ONCE-THROUGH BOILER

摘要

PROBLEM TO BE SOLVED: To prevent a water level widely different from an actual condition from being generated in a water level detector, when a combustion load of a large elevation level based on abrupt increase of a load is applied to boilers to be controlled in number.;SOLUTION: When the stand-by boilers are used as the objects for increase and decrease of a combustion level in load change control for the number control, a water feed pump is driven for a predetermined time t_c to replenish boiler water via a steam separator, in a time point where a time integration value of a load commanded during continuation of detection exceeds a preset load integration threshold value, when a water level exceeding a set upper limit water level LH continuously detected in the water level detector irrespective of an off-condition of the water feed pump for the boiler, and when a level higher than a set lower limit water level LL is continuously detected during the continuation thereof, in case that the elevation level of a load-commanded value from a stream header to the boiler is a predetermined elevation level or more.;COPYRIGHT: (C)2004,JPO