GB708421A - Liquid fuel supply systems for prime movers - Google Patents

Abstract

708,421. Gas turbine plant. LUCAS, Ltd., J. May 15, 1951 [May 22, 1950], No. 12733/50. Class 110(3) [Also in Group XXIX] In a liquid fuel supply system for prime movers such as jet propulsion engines or gas turbines of the kind in which one or more swirl-type burner nozzles connected to a spill pipe are supplied from a pump at a controllable rate, the means for controlling the rate of flow of fuel to the nozzle or nozzles includes a manually operable valve controlling ports through which can flow the whole of the fuel to be supplied to the burner, including the excess fuel to be returned by the spill pipe, and means including a throttle responsive to the pressure difference across a restricter orifice in the spill pipe are provided for automatically controlling the return of the excess fuel at a substantially constant rate. The arrangement shown in Fig. 1 is similar to that shown in Specification 585,127, [Group XXIX], except that the by-pass between the chambers p<SP>1</SP>, p<SP>2</SP> of the pump controlling means n is omitted and the ports 2, 3 are arranged to provide always a fuel flow in excess of the requirements of the prime mover. In this arrangement, a variable delivery fuel pump a as described in Specification 577,016, [Group XXIX], having a servo-piston b is controlled by a vent valve k operated through a lever 4 by a diaphragm x subject to the fuel pressure difference across a piston valve t controlling the port 2. The valve t is rotatably adjustable by a manually operable or other lever u. The valve t is movable axially under the control of a leak-off valve 13 operated through a lever 14 by a stack of capsules 8 exposed to atmospheric pressure through a passage 7. In Fig. 2, the pressure difference across a manually adjustable throttle 34 in the fuel supply pipe 48 to the burner nozzles i is communicated to a diaphragm 40 which operates on a lever 43 also acted on by an evacuated elastic capsule 45 and, by an opposed capsule 46 open to atmospheric pressure. The lever 43 operates the leak-off valve 44 of a servomotor controlling the output of the fuel pump 30. Excess fuel from the nozzles i is returned to the tank 31 at a constant rate by a device 50 comprising a spring-loaded diaphragm subject to the pressure difference across a restriction 54 and controlling a valve 51 in the return line 49. The controlling means n, Fig. 1, or the control device 33, Fig. 2, may alternatively control a throttle in the fuel supply pipe or a bypass whereby fuel is diverted from the supply pipe on its way to the nozzles i.