| 摘要 |
<p>PURPOSE:To prevent flushing in the case of a sudden change in plant load by sealing water using clean, high-pressure condensate downstream of a condensate purifying device and at the inlet of a high-pressure condensate pump CONSTITUTION:A sealing pipe line 22 branching from a condensate pipe line 9 at the delivery portion of a high-pressure condensate pump 8 is installed in the shaft seal portion of a high-pressure drain pump 20, and a temperature regulating valve 23 is installed in the sealing pipe line 22, for controlling the temperature of return water in response to a control signal from a temperature detection controller 24 installed in a sealed water return pipe line 25 leading from the shaft seal portion of the high-pressure drain pump 20. The return water is at the same pressure as atmospheric pressure and is collected into a return water collecting tank 26 by means of the sealed water return pipe 25 as gravity flow. Thereby the shaft seal portion of the high-pressure drain pump 20 is always controlled so that a pump suction temperature is about 50 to 60 deg.C, which is much lower than about 180 deg.C and higher. Therefore, even if pressure drop occurs as during the load shutdown of a plant, the shaft seal portion of the pump does not flush and so the function of sealing a shaft can be secured.</p> |
