GB904536A - Combined steam and gas turbine plant - Google Patents

Abstract

904,536. Generating combustion products under pressure; slag tap furnaces; air supply for combustion. CANADA, MINISTER OF MINES & TECHNICAL SURVEYS. Dec. 13, 1960 [April 8, 1960], No. 42797/60. Class 51 (1). [Also in Group XXVI] A combined steam and gas turbine power plant comprises a steam generator having a combustion chamber, the combustion chamber producing gases which contain fly ash, a superheater in which the steam is superheated by gases discharging from the combustion chamber, an air heater in which air is heated by gases discharging from the superheater, a steam turbine operated by the superheated steam, a gas turbine operated by air from the air heater, the air exhausting from the turbine being passed to the combustion chamber as combustion air, the combustion chamber being provided with a surface which is arranged to cool the combustion gases whereby the fly ash contained therein is cooled below its fusion temperature by the time the ash arrives at the air heater. The plant shown comprises a steam generator having a combustion chamber 14 and a radiation chamber 11, the walls of which are lined with steam generating tubes 13 which extend between a steam and water drum 25 and a distributer 64. Fuel such as pulverised coal is supplied to burners 18 from pulverizer 48, and air for combustion is supplied through ducts 45, 46 from the hot air turbine 42, air from the duct 46 passing to the annular manifold 20, through ducts 19 into the combustion chamber, and further air passing through ducts 47 to the annular distributer 21, this air constituting tempering air. After passing through the radiation chamber 11 the combustion gases flow first across the steam superheater tubes 29 and then across the air heater tube 38, finally discharging through outlet 39 to atmosphere. Steam passes from drum 25 through tube 27 to header 28 thence through the tubes 29 to the superheater drum 30, the steam then passing through duct 31 to the highpressure turbine 32. The steam then passes through duct 52 to the low-pressure turbine 53, the two turbines being mounted on a common shaft and driving generator 55. The exhaust steam passes to condenser 57 and the feed water is then pre-heated in heaters 60, 60A, 60B, 60C by steam bled from the turbines, and passes through duct 62 to the drum 25, thence through downcomer 63 to the distributer 64. Air compressed in the compressor 41 passes through the heater tube 38 where it is heated by the combustion gases, the heated air then acting on the turbine 42 which drives the compressor 41, also an electric generator 44. The air exhausting from the turbine passes through ducts 45, 46, 47 as referred to above, a further portion of the air passing to the pulverizer 48 and then through duct 50 to the burners 18. The combustion chamber comprises a slag outlet 18a. A burner assembly is shown in Figs. 2 and 3 and comprises a refractory surround 70, adjustable vanes 71 and an adjustable burner head 72. The vanes 71 are shown as comprising two sets 71a, 71b, the set 71a being adjustable by means of linkage 77a and the set 71b adjustable by means of linkage 77b. The burner head is adjustable by means of linkage 76. The water tubes 13 are shown disposed around the surround 70, and a gas ring 69 is disposed within the surround, electrical igniters 74 being provided as indicated. Pulverized coal and primary combustion air are supplied through inlet 75 and duct 75a to the burner head 72 while secondary air passes through inlet 82 controlled by dampers 84 into the chamber 83 thence through vanes 71. If heavy low-grade fuel oil is to be used instead of pulverized coal, the tube 80 and atomizer nozzle 81 are moved forwardly to the position indicated by broken line, the burner head 72 being moved to its normal position. An alternative arrangement for slag removal is described in which slag drips from the combustion chamber into a water tank and the slag beads are flushed away through a water pipe.