PURPOSE: To control boiler outlet steam temperature adequately responding to load change by controlling the concentration of ammonia supplied to the exhaust gas boiler of an ammonia-water mixed liquid cycle.
CONSTITUTION: The inlet feed-liquid ammonia concentration of the boiler 2 of an ammonia-water mixed fluid cycle is detected to operate a condensate pump outlet feed-liquid flow rate adjusting valve 8 so that feed-liquid has ammonia concentration wherein the outlet steam temperature of the boiler 2 becomes a prescribed value, that is, when the outlet steam temperature of the boiler 2 becomes higher (lower) than the prescribed value, the outlet feed-liquid flow rate of condensate pump 6 is increased (reduced) to increase (reduce) the condensate flow rate of low-ammonia concentration to lower (increase) the concentration of feed-liquid ammonia after mixing. Consequently absorbed heat from the boiler 2 is reduced (increased) to lower (rise) the outlet steam temperature of the boiler 2 to return to the prescribed value, controlling the outlet steam temperature of the boiler 2 which properly corresponds to the load change.
TAKI MASATO
IWAI MASATAKA
KAMATA TOSHIHIRO
MITSUBISHI HEAVY IND LTD