GB764128A - Steam generating unit - Google Patents

Abstract

764,128. Regulating steam temperature in boilers. RILEY STOKER CORPORATION. Jan. 13, 1955. No. 1054/55. Classes 123(2) and 123(3) - In a water-tube boiler having a furnace 16 lined with steam generating tubes which extend from lower headers 19, 20 to an upper steam and water drum 21, combustion gases leave the furnace through a lateral pass 42 locating the high temperature sections 52, 59 of the superheater and reheater respectively and then flow downwardly in three passes 35, 39, 37 controlled individually by damp e r s 40 and leave the boiler through an air heater 31. The intermediate downpass 39 locates the low temperature section 24 of the superheater, some of the superheater tubes extending through the front wall 36 of the pass to protrude into pass 37. Below the low temperature superheater is disposed as economizer 23 the tubes of which extend through all three passes but which also has a section 45 disposed wholly within pass 37. The low temperature section 58 of the reheater is located at the top of pass 39 in such a position that it is also subjected to heat transfer from gases flowing into pass 35 when the dampers of that pass are opened Steam to be reheated enters an inlet header 54, passes upwardly through radiantly heated tubes 56 and then in series through the sections 58, 59 to an outlet conduit 60. In operation, at a given load say at 75 per cent of full load, the required temperature of superheat and reheat is attained with passes 35, 37 shut off. If for example, the load increases above 75 per cent, the proportion of heat required for superheating to that required for reheating also increases and the dampers controlling pass 37 are opened to expose superheater coils 49 to gases which have not contacted the reheater section 58. The pass 35 is used as required to temper the effect of the gas flow in pass 37 and to provide a fine adjustment of reheat temperature. The economizer section 45 prevents excessive temperature at the outlet from pass 37 of gases which have contacted only the small portion 49 of the superheater.