| 摘要 |
PROBLEM TO BE SOLVED: To prevent the pressure drop in a deaerator to prevent cavitation of a feedwater pump and further, prevent short water of a boiler caused by the residual heat by rapidly throttling a feedwater adjusting valve at the time of cut-off of fuel. SOLUTION: A feedwater adjusting valve 14 is rapidly throttled when fuel is cut off to restrict feedwater to a boiler 1. In this time, a feedwater pump 12 does not stop and even though the feedwater adjusting valve 14 is completely closed, it is shifted to a recirculation operation to run continuously. The quantity of feedwater restricted by throttling the adjusting valve 14 is equivalent to approximately 5-30% of that in a rated operation. In this way, cavitation of the feedwater pump 12 can be prevented by controlling the pressure drop in the deaerator 11, and short water of the boiler caused by the residual heat in the boiler 1 can be prevented by continuously supplying water to the drum of boiler 1.
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