HEAT RECOVERY STEAM GENERATING ARRANGEMENT EMPLOYING MEANS FOR PREVENTING ECONOMIZER STEAMING

摘要

1315806 Steam generators WESTING- HOUSE ELECTRIC CORP 21 Oct 1971 [17 Dec 1970] 48974/71 Heading F4A A steam generating plant has a high pressure boilder 68 which supplies steam to a steam turbine 24, 26 exhausting into a condenser 36 from which the condensate is supplied through conduit 46 to a low pressure boiler 56 and is then fed by pump 60 through an economizer 62 and water-level control valve 64 to the high pressure boiler 68, the outlet of the economizer being connected also by a recycle conduit 78 and pressure regulating valve 80 to the condensate supply conduit 46 for permitting return of water which does not pass through the level control 64. The boilers 56, 68, economizer 62 and a superheater 74 are provided in a heating stack 22 supplied at 20 with waste heat gases from the exhaust of a gas turbine 10, 12 which drives a three-phase generator 18. Fuel burners 76 are also used when the plant is on full load. Seam leaving the superheater 74 is fed through main steam valve 32 to the HP turbine 24 and then through LP turbine 26, both connected by shaft 28 to a three-phase generator 30. The condensate from 36 is supplied by pump 38 through a heat exchanger 40 and check valve 42 to a deaerator 44 where it is also heated by low pressure steam from conduit 50 and also steam from the LP boiler drum 54. The constant flow pump 60 feeds water from this drum into the economizer 62 and then to the steam/water drum 63 of the HP boiler 68. The water level in this drum is detected by a sensor 72 which controls the feed water level valve 64. When this valve is wholly or partially closed due to low load conditions, the feed water or high pressure is diverted along recycle conduit 78 through the heat exchanger 40, wherein it is cooled, and pressure regulating valve 80 to mix with the condensate in conduit 46.