| 摘要 |
PURPOSE:To control a drop of water level inside a drum at an abrupt reduction of operating load in a drum type boiler, by proving a burning amount control circuit a variation rate limiting function effective for a loading side. CONSTITUTION:A control signal obtained from a deviation of main steam pressure is added to a main steam flow rate signal 5 for obtaining a burning amount set valve 7. A burning amount control circuit is further provided with a variation rate limiting circuit. The variation rate limiting circuit comprises a minus bias device 8 for adding a negative vias to the burning amount set valve 7, a variation rate limiter adapted to actuate upon the burning amount set value 7 being abruptly varied and a selector 10 adapted to select an output value of the burning amount set value 7 or the variation rate limiter 9, whichever the larger. |
