GB765339A - Liquid fuel supply systems for prime movers - Google Patents

Abstract

765,339. Gas turbine plant; centrifugal pumps. LUCAS (INDUSTRIES), Ltd., J. July 21, 1954 [July 28, 1953], No. 20868/53. Classes 110 (1) and 110 (3). In a liquid fuel supply system for a prime mover such as a jet propulsion or gas turbine plant, of the kind in which the fuel is supplied to a burner by a centrifugal pump driven at a speed corresponding to that of the prime mover, a positive-displacement pump is arranged in parallel or series with the centrifugal pump, and a valve normally closed by a spring and responsive to fuel pressure short-circuits the positive-displacement pump when the speed of either pump is adequate to produce a pressure which will open the valve. Fig. 2 shows a centrifugal pump a delivering liquid fuel by way of a non-return valve h and a manual or automatic flow control d to a burner b. A positive displacement pump, such as a gear pump e, is connected in parallel with pump a by way of pipes f, g and non-return valve i. Both pumps are driven by the gas turbine or an associated source of motion, and at low speeds the burner b is supplied by pump e. When the delivery pressure of pump e has risen to a predetermined value, the pressure in pipe g moves a piston n to open a valve k against the action of a spring m to short-circuit the pump e through a by-pass j. The burner b is then supplied by pump a. Instead of being connected, as shown, to pipe g the cylinder containing piston n may be connected to the delivery side of pump a; valve k is then opened by pump a instead of pump e. A valve q, operable by an electromagnet r or other means, may be provided. When valve q is closed, the system operates as described above, but when it is opened, it connects to the pipe g a by-pass s containing a pair of restricted orifices t, the space between the orifices t being connected to one end of the cylinder containing the valve k. Valve k then remains closed until the pressure in pipe g reaches a higher value than would otherwise have sufficed to open it. Fig. 3 shows an alternative arrangement in which pump e is arranged in series with pump a. When the discharge pressure of pump a reaches a predetermined value, it acts by way of a passage w to open a valve u against the action of a spring v, thereby short-circuiting pump e. Passage w may alternatively be situated in the position shown dotted, in which case the valve u is opened by the discharge pressure of pump e.