Patent GB-1481682-A (GB)
Title: Power systems
IPC: F01K7/22
Filed: 1973-07-12
Abstract: 1481682 Power systems; gas turbine plant NATIONAL RESEARCH DEVELOPMENT CORP 10 July 1974 [12 July 1973] 33503/73 Headings F1G F1Q and F1T [ Also in Division F4] A power system comprises a heat-insulated storage container 1 in which is stored in liquid form a working fluid which is gaseous at standard temperature and pressure and is of non-toxic and/ or non-inflammable nature, self-contained means 5 for supplying heat, such as heat storage means or chemically reacting means, a pump 3 for transferring liquid working fluid from the container to the heat supply means, either directly or through one or more heat exchangers, and means such as a turbine 6 for converting heat energy of the heated gaseous working fluid into mechanical power. The heat supply means has a thermal capacity sufficient to raise the temperature of the working fluid at least 200C above its critical temperature, which in the case of nitrogen is -147C. The heat exchanger 4 shown in Fig. 1 is heated by ambient air and constitutes a vapourizer. In Fig. 2 the working fluid is further heated in a heat exchanger 7 by the exhaust gas discharging from the turbine 10; also in this embodiment two turbines 9 and 10 in series flow are provided, the working fluid being reheated in the heat supply means 8 after expansion in the high-pressure turbine 9. In Fig. 3 working fluid from the container 1 is first heated in the heat exchanger 11, further heated in heat exchanger 7 by exhaust gas discharging from the turbine 10, then heated in the heater 8; the heated fluid is then expanded in HP turbine 9, reheated in the heater 8 and finally expanded in LP turbine 10, a portion of the fluid discharging from the turbine 10 passing through heat exchanger 7 before discharge to atmosphere, the remaining portion of the fluid passing to the heat exchanger 11 where it is cooled, then passing to a compressor 13, the pressurized fluid then passing through the heat exchanger 12 where it is heated by heat exchange with the portion of fluid discharging from the turbine 10; the pressurized fluid is then passed to mix with the fluid discharging from the turbine 9 to the reheat pass of the heater 8. In Fig. 6 fluid from the container 1 is passed through a heat exchanger 22, then through a heat exchanger 27 before passing to the heater 8. The heated fluid then passes to HP turbine 9, is  reheated in the heater 8, then passing to the LP turbine 10 from which it discharges through the heat exchanger 27 to atmosphere. The heat exchanger 22 is in a conventional heat engine system which comprises an air compressor 23 which supplies air through a heat exchanger or air pre-heater 24 to a heater 25 of heat storage type, the heated air then passing to turbine 26 from which it discharges through the air pre-heater 24, thence through the heat exchanger 22 and back to the compressor 23. A heat storage unit is shown in Fig. 4 and comprises an inner container disposed within an outer casing 19, there being insulation material 20 therebetween. The inner container contains a material 16 such as a fusible salt e.g. alkali or alkaline earth metal halides, the material being heated by an electrical element 21 so that it becomes molten. The fluid to be heated is passed through helical tubes 17, 18 disposed within the molten material 16.