JPS6454102A - Feedwater controller - Google Patents

Abstract

PURPOSE: To improve a reliability in operation of a feedwater control device in a steam power generating facility by a method wherein a difference between a boiler feedwater command and a discharging flow rate of a feedwater pump is corrected in gain when the feedwater pump is started or stopped in its operation and then a variation of the flow rate of main feedwater is restricted to a minimum value. CONSTITUTION: When a feedwater pump is stopped or started in its operation, a changing-over switch 19 is changed over to a terminal (a) of a second gain setting device 20 and a set value S for reducing a command for a degree of opening of an outlet flow rate adjusting valve 5 is given a multiplier 18. Owing to this fact, a difference between a boiler feedwater command 8 and a discharged flow rate 9 is multiplied with a set value S at a multiplier 18 to become a small value, resulting in that this value is inputted to a proportional integrator 10. That is, a gain correction is carried out at a control system of an outlet flow rate adjusting valve 5 and a variation in opening or closing of the outlet flow rate adjusting valve 5 and a minimum flow adjusting valve is restricted low. As a result, it is possible to restrict a variation in flow rate of main feedwater.