GB679733A - Improvements in or relating to plant for the recovery of waste heat from furnace gases - Google Patents

Abstract

679,733. Gas turbine plant. SPENCER-BONECOURT, Ltd., and GREGSON, W. Oct. 20, 1950 [Oct. 21, 1949], No. 27139/49. Class 110(iii) A plant for the recovery of heat from waste gases of an industrial furnace comprises a gas turbine, a compressor for supplying working fluid to the gas turbine, a heat exchanger in which the waste gases impart heat to the working fluid, a vapour generator heated by the waste gases from the heat exchanger and/or by the working fluid exhausted from the gas turbine, and a prime mover driven by the vapour. The hot waste gases pass by way of a duct 1, Fig. 5, to a heat exchanger 11, where they impart heat to gas flowing through tubes 13, and then pass through one or both of boilers 23, 25, leaving by way of the corresponding stacks 3, 5. The gas which has been heated in the tubes 13 drives a turbine 49 and then passes by way of a regenerator 47 and a heat exchanger 151 to compressor stages 41, 43. The compressed gas is heated in the regenerator 47 before returning to the tubes 13. An intercooler 45 is provided. The regenerator 47 may be eliminated. A pre-cooler may replace the heat exchanger 151. When the industrial furnace is started up from cold, waste gases from duct 1 are passed directly to the stacks 3, 5 until the temperature of the gases has risen sufficiently. Then, with dampers 7, 9, 15 and 17 closed and dampers 21 and 27 and/or 29 partly or fully open, fans (not shown) draw the waste gases through a byepass 19 and one or both of the boilers 23, 25 and discharge them to one or both of the stacks 3, 5. The steam thus raised drives a turbine 59 mounted on the same shaft as the compressor 41, 43, turbine 49 and a generator 57. Dampers 15, 17 and 21 are then manipulated to divert the waste gases through the heat exchanger 11, bringing the turbine 49 into operation. If desired, the turbine 59 can then be shut down and uncoupled from the drive, the boilers 23, 25 then providing hot water or steam for other use. An auxiliary firing means 153 may be provided, its burner being controlled manually during the starting operation and automatically, as by means responsive to turbine speed, during normal operation. Instead of flowing through the same section of the heat exchanger 11 as the waste gases, the gases from the auxiliary firing means 153 may flow through a separate section or a separate heat exchanger. Alternatively, the auxiliary firing means may comprise a combustion chamber directly associated with one or both of the boilers 23, 25. The compressor and generator may be separately driven. The plant may be of the open-circuit type. Fig. 2 shows the layout of the plant, with the boilers 23, 25 on the lower floor 85, the stacks 3, 5 and heat exchanger 11 on the upper floor 81 and the waste gas duct 1, turbines 49, 59, compressor 41, 43 and generator 57 on the middle floor 83. The regenerator 47, intercooler 45 and a pre-cooler 53 are mounted on a staging 87. Each boiler 23 or 25 is connected to its respective stack 3 or 5 by way of a fan 135 and a duct 139. Specification 603,874 is referred to.