Patent GB-628759-A (GB)
Title: Improvements in or relating to thermal power plants
IPC: F02C1/00
Filed: 1947-01-23
Abstract: 628,759. Heating systems and apparatus; heating and cooling gases by direct contact. RICARDO, H. R., and ALCOCK, J. F. Jan. 23, 1947, No. 2118. '[Classes 64(i) and 64(ii)] [Also in Groups XXVI and XXVIII] A thermal power plant in which a continuously-gaseous working fluid circulates through a compresser driven by a turbine which is itself driven by the working fluid, and through two heat exchangers in one of which the working fluid is heated before passing to the turbine while in the other it is cooled after passing through the turbine, is characterized in that the heat exchangers are of the kind in which heat is respectively transferred to and extracted from the working fluid by a liquid passing through the heat exchanger. Further, this liquid is caused to flow in a liquid circuit including a heating device outside the working fluid circuit from which the liquid flows to the heat exchanger in which the working fluid is heated, and then to a heat exchanger in which the working fluid is cooled when it is returned to the heating device, the heat-transfer liquid and the gaseous working medium passing through the first heat exchanger in contra-flow and the temperature-drop in the working fluid in its passage through the turbine being less than the temperature-difference between the working fluid and the liquid respectively leaving the first heat exchanger. In the form shown, the heat-conveying liquid is heated in a coil A by the combustion gases from a burner C which are caused to pass through a heat exchanger D on their way to the outlet B<SP>2</SP> in order to preheat the combustion air entering at B<SP>1</SP>. The heat-conveying liquid from the coil A is delivered by a pump A<SP>1</SP> into a heat exchanger E through a downwardly-directed spray nozzle A<SP>2</SP>. The gaseous working fluid delivered by a compresser F driven by the turbine G is delivered by piping H into the lower part of the heat exchanger E and passing upwards is heated by contact with the downwardly-directed spray of liquid from the jet nozzle A<SP>2</SP>. After passing through a separater J for removal of any spray that may be carried over and which drains back through piping E<SP>2</SP>, the heated gas under a substantial pressure, is delivered to the turbine G through piping K from whence it is delivered through the pipe L<SP>1</SP> to the lower end of a second heat exchanger L where it is met and cooled by a downwardly-directed spray of liquid issuing from a nozzle M to which is delivered through piping E<SP>3</SP> by gravity or other means, the liquid which has accumulated in the bottom of chamber E. Before being delivered to the compresser F, the temperature of the gaseous working fluid is further reduced by passing it through a heat exchanger N in which water is the cooling medium. The liquid which collects at the bottom of chamber L is delivered through piping L<SP>2</SP> to the upper end of the coil A for reheating. In a modification, the function of the heat exchanger E may be divided between two heat exchangers in one of which the gas meets the heatconveying liquid from the heater A, while in the other, the gas meets the liquid from chamber L. Examples of suitable heatconveying liquids mentioned are the metals gallium, sodium and potassium alloys, and fusible alloys similar to Wood's metal; also salts comprising a mixture of lithium nitrate (23.3 per cent), potassium nitrate (60.4 per cent), and sodium nitrate (16.2 per cent), or, alternatively, a mixture of lithium chloride (45 per cent) and potassium chloride (55 per cent), all of which are said to be liquid over the necessary temperature - range. The gaseous working fluid is preferably nitrogen, but it is stated that argon could be used.