Patent GB-1407531-A (GB)
Title: Steam power stations
IPC: F01K3/02
Filed: 1973-07-11
Abstract: 1407531 Steam turbine plant utilizing heat accumulator BABCOCK-ATLANTIQUE 11 July 1973 [13 July 1972 26 Jan 1973 (2)] 33127/73 Heading F1T [Also in Division F4] A power station comprises a steam generator and a steam turbine, and an accumulator arranged to withdraw heat from the installation by transfer with a heat-transfer fluid, to store said heat and subsequently to restore it to the installation for operation thereof, the heat-transfer fluid being in heat exchange relation with steam of which part at least has performed work in the turbine. The plant comprises a steam generator 1, an HP turbine 2, inter-stage reheater 15, and LP turbine 3, condenser 4 extraction pump 20 and feed pump 22. The turbines drive an electric generator 5. The plant comprises also an accumulator 29 in which heat may be stored and subsequently utilized. The condensate from condenser 4 passes through feed water heaters 11, 10 which are heated by steam tapped from the LP turbine 3, the feed water then being further heated in pass 21 of a heat exchanger 18, finally returning to the steam generator 1. The flow of heat-transfer fluid is indicated in broken lines, the flow in Fig. 1 being that in which heat is being stored in the accumulator 29. From point 24 in the flow, heated fluid passes through pump 25 to the pass 26 of the inter-stage steam reheater 15, the fluid then flowing through pass 27 of heat exchanger 18 where it is utilized to heat feed water in pass 21; the fluid then flows in series through the heaters 9, 8, 7, 6 where it is heated by steam tapped from the HP and LP turbines 2, 3, the fluid then passing through a heat exchanger 28 where it is further heated by live steam taken from the point 14 adjacent the outlet of the steam generator, the fluid then passing to point 24 to repeat the flow. A portion of fluid passes from the point 24 to the heat accumulator 29 then passing through the pump 30 and valves 31, 32, which are open in this phase of operation, to the point 36 to unite with the fluid which has flowed through the exchangers 15 and 18. The live steam discharging from the heat exchanger 28 at point A returns to the feed water circuit downstream of the pass 21 at point 23. The pump 25 is controlled by a regulator 37 in dependence on temperature M of the feed water at a point downstream of the pass 21. The pump 30 is controlled by a regulator 35. The valves 33, 34 are closed in this phase of operation. When full output is required from the plant, the heat stored in the accumulator is utilized. Heat transfer fluid now flows in a reverse direction through the accumulator 29 from the point 36 to the point 24 whereby heat from the accumulator is utilized in the inter-stage steam reheater 15 also in the feed water heater 18. In this phase of operation the valves 31, 32 are closed and valves 34, 33 open; also the bleed steam valves are closed. In Fig. 3 the heat accumulator 29 is located away from the power station and heat transfer fluid flows through pass 38 of the heat exchanger 39 to and from the accumulator. In the heat storage phase of operation feed water taken from point 42 passes through heat exchanger 44 where it is heated by live steam taken from the outlet 60 of the steam generator. The heated feed water divides at point 8, one flow passing through pump 58 to the heat exchanger 15 where it is utilized to reheat inter-stage steam, the feed water returning to the feed water line at point A. The second flow from point 8 passes to the pass 40 of heat exchanger 39 where it heats heat-transfer fluid in the pass 38; the second flow then passes through open valve 48 and pump 50 to the feed water line at point 43. Steam tapped from the HP turbine 2 for the feed water heater 52 discharges through the pass 41 of heat exchanger 39 then discharging through open valve 53 and pump 54 to the feed water line at point 55. When increased power is required the valves 46 and 45 are closed so shutting off the heat exchanger 44; the valves 48 and 53 are also closed and the valves 47 and 56 downstream of the pumps 49 and 57 are opened. Feed water is now taken from the feed-water line at point 43 and flows through pass 40 of heat exchanger 39 whereby it is heated by flow of heat transfer fluid in pass 38, the heated feed water passing through pump 58 to the inter-stage reheater 15, then returning to the feed water line at point A. The pump 57 takes feed water from point 58 and discharges it through open valve 56 to the pass 41 of the heat exchanger 39 where it is heated by heat transfer fluid from the accumulator 29; the feed water then returns to the feed water heater 52 where it mixes with the flow of feed water. Thus heat is transferred back to the working fluid from the heat storage accumulator. Other embodiments are described.