Improvements in tubulous vapour generating, superheating and reheating units and an improved method of generating, superheating and reheating high pressure, high temperature vapour

摘要

806,763. Boiler furnaces. BABCOCK & WILCOX Ltd. Nov. 29, 1956 [Nov. 30, 1955], No. 36535/56. Class 51 (1). [Also in Group XIII] A water-tube boiler includes a superheater furnace chamber 24, a reheater furnace chamber 22, separately controllable fuel burners, such as 26 ... 29, for each furnace chamber and separate gas passages leading respectively from the two furnace chambers 24, 22. The burners are disposed in four widely spaced vertical rows and are preferably capable of burning a variety of fuels such as oil, gas and coal and of burning more than one of the fuels simultaneously. As the demand for steam varies, the total rate of firing is varied, the furnaces being fired differentially, and as the distribution of fuel within them is varied, the steam demand can be met, as well as the superheated and reheated steam temperatures maintained, at respective predetermined values. The gas flows from the furnace chambers 24, 22 are separated by walls of steam generating tubes 18, 20 and by division walls 160, 162. Steam is also generated in tubes 46 lining one side wall of the furnace chamber 24 and in tubes 50, 52, 54, 55, 56 lining the rear walls or forming roof tube portions in both furnace chambers, these tubes leading from lower headers, for example 32, 34, 58, directly or indirectly to a steam and water drum 44, the lower headers being supplied from downcomers 60. Steam flows from the drum 44 through circulators 104 to two upper side wall headers 106, one in each of the gas passes 108, from which headers it flows down side wall tubes 110 to lower headers 112 which are connected to a header 114 from which the steam passes through tubes 116, 118, 121, 124 to a header 120, and then by way of circulators 126 to an inlet header 62 leading to an intermediate section of the primary superheater consisting of tubes 64 lining the front wall of both furnace chambers 24, 22 and which lead to an outlet header 66, steam flowing down one half of the tubes 64 and up the other half of the tubes. From the outlet header 66 steam flows through circulators 130 to an inlet header 132 of an intermediate primary superheater convection section 134, disposed in the convection passes of both furnace chambers 24, 22. From the outlet header 136 of the superheater 134 the steam flows through at least one conduit 138 leading through an interstage spray attemperator to an inlet header 140 of a secondary, high temperature, superheater 142 disposed in the superheater furnace chamber 24 only and formed of widely spaced platens 142SP1/SP (Fig. 3), more narrowly spaced and smaller platens 142SP11/SP and still more narrowly spaced and still smaller platens 142SP111/SP leading to an outlet header 144 which delivers steam by way of a conduit 146 to the inlet of the steam turbine. Exhaust steam from a high pressure or intermediate turbine stage is received by a lower header 76 in the reheater furnace chamber 22 and passes up tubes 74 to an upper header 78 from which it flows through circulators 80 to a header 82 of a reheater section consisting of platens 86 to 89, disposed in the reheater furnace chamber 22, similar to the platens of the superheater section 142 described above the platens 89 leading to an outlet header for delivery of steam to the inlet of another turbine stage. Economizer tubes 164, 166 are disposed in the downward gas passes 108 and differentially operable sets of proportioning dampers 172 are disposed at the outlets of the downward gas passes 108.