GB731338A - Improvements in or relating to a steam generating power plant and method of producing steam - Google Patents

Abstract

731,338. Steam superheaters; water-tube steam boilers. COMBUSTION ENGINEERING, Inc. Sept. 23, 1953 [Oct. 9, 1952], No. 26210/53. Classes 123 (2) and 123 (3). The steam generator of a steam power plant operating with a reheat cycle has a vertical furnace chamber A fired by corner-mounted, tilting burners 21 the combustion gases from which leave the furnace through a lateral pass D locating successively the high temperature section 22 of a superheater and the tube banks 24, 26 of a reheater and then flow downwardly through a pass E in which is positioned the tube banks 28, 29, 30 of the low temperature section of the superheater and an economizer 32. The furnace A and lateral pass D are lined with steam generating tubes extending from lower headers 6, 17, 18 to a steam and water drum 11. The steam from the drum passes to a header 48 and thence through tubes 49, 52 lining downpass E into headers 51L, 51R from which it passes through superheater banks 30, 39, 28 to a header 56. From this header the steam flows through a pipe 58 wherein its temperature is adjusted by an attemperator spray 62, the steam then passing successively through a heatexchanger H in indirect contact with steam to be reheated and through superheater 22 to the high pressure stage of a turbine 80. A second attemperating spray 75 is provided in the pipe 74 leading from the heat exchanger to super heater 22 to regulate the final temperature of superheat. Steam to be reheated passes from the turbine through pipe 84, through the heat exchanger H and reheater 24, 26 and returns to the low pressure stage of the turbine through pipe 90. As shown in Fig. 2, the heat exchanger H consists of a row of pendent U-tubes 64 each mounted axially within a larger diameter U- tube 68. The temperature of superheat and of reheat is controlled overall for any given combustion rate by adjusting the tilt of burners 21, control by gas. recirculation and gas by-passing being used in conjunction with this tilting burner control if desired. Individual control of superheat temperature is obtained by regulating the water supply to spray 75 whilst for individual control of reheat temperature the water supply to spray 62 is regulated manually or automatically to control the temperature of the partially superheated steam entering the heat exchanger H and thus indirectly to control the reheat temperature. Spray desuperheating of the steam to be reheated is thus eliminated and the load range over which the superheat and reheat temperatures can be held constant is considerably extended.