Patent GB-802502-A (GB)
Title: Improvements in or relating to gas turbine plants
Filed: 1954-10-11
Abstract: 802,502. Axial flow compressors; gas turbine plant. BROWN, BOVERI & CIE, A.G. Oct. 11, 1954 [Oct. 9, 1953], No. 29222/54. Classes 110 (1) and 110 (3). [Also in Group XXIX] In a gas turbine plant for the production of compressed air comprising a compressor supplying air to a combustion chamber feeding a turbine driving the compressor and another compressor supplying air to a load, a conduit with control means is provided to connect together an outlet of each of the compressors, the control means being controlled by a speed governor driven by the turbine and means responsive to the load demand. A gas turbine 1 drives compressors 2, 3 through a shaft 11. The compressor 2 supplies air through a heat exchanger 4 to a combustion chamber 5 supplied with gaseous fuel by a blower 6. The compressor 3 supplies air to a load through a conduit 29 provided with a meter 7 which maintains the volume or pressure constant. The meter 7 controls a leak-off valve 8<SP>1</SP> through a spring-loaded diaphragm 8. An oil pump 27 supplies oil under pressure through orifices 23 to control lines 24, 25, 26. Control line 24 is connected to servomotor 13, which actuates a sleeve 14 of a control element in line 25 which includes a piston actuated by the speed governor 15, to the leak-off valve 8<SP>1</SP> and to one end of the servomotor cylinder 9 which operates a leak-off valve 10 in the control of a servomotor 11 which adjusts a throttle 12 in the inlet of the blower 6. The servomotor 9 is connected to a servomotor 16 having one end connected to the control line 25 and its opposite end to the buffer space 17, the opposite ends of the cylinder being connected by a calibrated orifice 18. The control line 26 is connected to the line between the servomotors 9 and 11 and is provided with a leak 20 controlled by a thermally-responsive element 19 mounted in the intake of the turbine 1. The element 19 prevents the temperature at the turbine element exceeding a predetermined value. The discharge of the compressor 2 is connected to the discharge of the compressor 3 and the load line 29 by a conduit 22 having a throttle valve 211 actuated by a servomotor 21 fed from the control line 25. Assuming that the plant is designed so that under normal conditions air from the compressor 2 flows through conduit 22 to the load, a decrease in the volume or pressure of the effective air will open the leak-off valve 8<SP>1</SP> and the resulting decrease in pressure in the control line 24 will cause the piston in the servomotor 9 to move downwards and open the leak-off valve 10 and thus tend to open the throttle valve 12. The turbine 1 would then accelerate. If the plant is operating at maximum turbine inlet temperature, the thermal element 19 will prevent further increase of temperature and the pressure in the control line 24 will then cause the servomotor 13 to move the sleeve 14 to decrease the pressure in the control line 25. This in turn will cause the servomotor 21 to close the throttle 21<SP>1</SP> and reduce the amount of air supplied by the blower 2 to the line 29. This will result in acceleration of the turbine. If the plant is designed so that the compressor 3 develops a higher pressure than the compressor 2, the control of the valve 21<SP>1</SP> would be arranged to divert air from the compressor 3 to the combustion chamber on decrease of volume or pressure in the line 29. In a modification, an intermediate stage of the compressor 2 is connected to the discharge of the compressor 3 through an air turbine connected to the shaft 1<SP>1</SP>. The control valves of the air turbine are controlled by the pressure in the control line 25. Reference has been directed by the Comptroller to Specification 696,192.