GB1029053A - Improvements in or relating to fuel control arrangements - Google Patents

Abstract

1,029,053. Fluid-pressure servomotor systems. POWER JETS (RESEARCH & DEVELOPMENT) Ltd. April 16, 1964 [April 18, 1963], No. 15427/63. Heading G3P. [Also in Division F1] The flow of gaseous fuel to the burners of a gas turbine is controlled by a valve responsive to the calorific value of the fuel. A turbine 3, Fig. 1, drives a compressor 1 which supplies air to a combustion chamber 5 and the exhaust of the turbine 3 is fed to a free turbine 9 not mechanically coupled to the turbine 3. The flow of fuel to burners 6 is controlled by a valve having two closure portions 16, 17 cooperating with seats 22, 23. The calorific value of the fuel is measured by the density, a sample of fuel being circulated through a sphere 50 mounted on a lever arm 51. Variations in the weight of fuel in the sphere 50 acts on a lever 53 to actuate a valve 66 which controls supply and exhaust of fluid to the opposite sides of a piston 68. Movement of the piston 68 recloses the valve 66 through lever 53 and also acts through levers 71, 72, 74, 70, 77, 79, 80 and 20 to adjust the fuel control valve. The fuel control valve is normally positioned directly in response to speed and compressor outlet pressure. A speed governor 32 acts on the valve through levers 34, 35 and 19 while the compressor outlet pressure acts on a diaphragm 46 to actuate the fuel control valve through rod 43 and levers 70, 77, 79, 80 and 20. Under normal condition the calorific control is overridden by speed and pressure control but operates during acceleration to prevent stalling. In a modification, the piston 68 actuates a valve controlling the leakage of compressor outlet pressure acting on the diaphragm 46. In a further modification, the piston 68 is not connected to the lever 53 and movement of this piston acts on a valve controlling the pressure on a further piston connected to the lever 53 to provide a feedback. In Fig. 4 (not shown) variations in the weight of fuel in the sphere 50 adjusts the loading of a spring 133 acting on a valve 135 which controls the supply and exhaust of fluid to a line 142 to act on a diaphragm 148 which positions the fuel control valve. The valve is again closed when the pressure in the line 142 balances the spring loading. In a modification, the lever 51 acts directly on a spool valve controlling the supply and exhaust to opposite sides of a piston, and the fuel control valve closure member is carried by the piston rod. In Fig. 8 (not shown) the weight of fuel in sphere 50 adjusts a valve 224 which controls leakage from a manifold 222, 223. Restriction of this leakage increases the pressure in a conduit 225 which acts in a closing direction on a valve 236 to increase the pressure in conduit 220. This increase in pressure acting on the valve 224 balances the movement of the valve and the pressure in conduit 220 acts to adjust the leakage through valve 234 to vary the compressor outlet pressure acting on diaphragm 95 to actuate the fuel control valve.