Patent GB-1068666-A (GB)
Title: Improvements in or relating to gas turbine power plants
IPC: F02C1/00
Filed: 1963-12-04
Abstract: 1,068,666. Air heating apparatus. ESCHER WYSS A.G. Dec. 4, 1963 [Dec. 6, 1962], No. 47919/63. Heading F4S. [Also in Division F1] The invention relates to a gas turbine plant which in the upper power range operates as a closed circuit plant, the gaseous working medium such as air being at a pressure greater than atmospheric pressure throughout the circuit, and which in the lower power range operates as an open circuit plant, suitable ducting and control valves being provided. The plant shown in Fig. 1 comprises low-pressure and high-pressure compressors 1, 2 which are driven by a high-pressure turbine 3, the working fluid from the turbine 3 passing to a separate power turbine 4 which in the embodiment shown drives a ship's screw 6. An intercooler 7 is provided between the compressors 1 and 2. An air heater 9 is provided for use when the plant is to be operated on closed circuit, and a combustion chamber 30 for use on open circuit. When the plant is operating on closed circuit, the valve 33 in the line 8 is open and the valve 29 in the line 28 is closed so that air discharging from the compressor 2 passes to the indirect air heater 9 where it is heated by combustion gases produced in the chamber 17. Air is supplied to the chamber 17 by means of a blower 18 which draws in air through filter 19 and discharges it through the non-return valve 20. Fuel is supplied to the chamber by means of pump 14 and line 16 and is controlled by valve 15. The combustion gases discharge through outlet 22. The air from the heater 9 passes through line 10 to the turbines 3 and 4 and then passes through line 11 where it is cooled in a cooler 12 back to the suction side of the compressor 1. The valve 38 in the line 11 is open and the valves 35 and 35<SP>1</SP> closed in this phase of operation, An auxiliary compressor 13 is provided so as to maintain the pressure in the circuit above atmospheric. When the plant is to be operated on open circuit, the valve 33 is closed and valve 29 opened so that air from the compressor 2 now passes to the combustion chamber 30, the combustion gases from which pass to the turbines 3, 4 and then through line 11 and the valve 35<SP>1</SP> which is now open, to atmosphere. A portion of the turbine exhaust gases pass through line 36 and the valve 35 which is now open, to the duct 21 and chamber 17, past the air heater 9, and discharges through outlet 22. In the open circuit phase of operation, air is drawn into the compressor 1 through filter 19, line 26 and non- return valve 27 the valve 38 in line 11 being closed. The combustion chamber 30 and the air heater 9 may be combined in a single unit as shown in Fig. 2. When operating on a closed circuit, air is supplied by the blower 18 to the combustion chamber 39, the combustion gases from which discharge across the tubes 41. of the air heater 9 and thence through the open valve 50 and outlet 49 to atmosphere. Air passes from the compressor through duct 8 and the open valve 33 to the air heater, and the heated air passes through a series of ducts 47 to the annular manifold 46 and thence into the duct 10 and so to the turbines. When operating on open circuit, the valve 33 is closed and valve 29 opened so that air under pressure passes to the combustion chamber 39, combustion gases from which pass through the valve 45 into the duct 10. The valve 50 is closed in this phase of operation. A by-pass passage 51 having a control valve 52 is provided across the valve 33 so that when the valve 33 is closed during opencircuit operation, a bleed of air may be caused to pass through the air heating coils 41 to prevent overheating thereof.