| 摘要 |
<p>PURPOSE:To reduce load flow rate of a main flow control valve, thereby improv ing controllability thereof by providing a control device for controlling the opening of a main flow control valve based on combustion gas temperature measured by a temperature sensor and an auxiliary flow control valve provided in a bypass pipe which opens and closes based on the opening of the main flow control valve. CONSTITUTION:When the opening of a main flow control valve 21 has reached a predetermined opening, an auxiliary flow control valve 23 is opened to lead part of returned water to a bypass pipe 22, so that the control level of the quantity of the returned water is increased by the amount of water passing through the pipe 22. As a result, the control capacity of the valve 21 is restored with respect to the amount of returned water exceeding maximum flow rate of the valve 21 so that the amount of spray water rate at a gas cooling nozzle 3 can be precisely maintained by proportional control similar to the control before the valve 23 was opened. And, since load flow rate to be controlled by the valve 21 decreases, operation can be shifted to an intermediate opening range where opening change and flow change are properly proportional, and hence controllability can be improved.</p> |
