GB850469A - Improvements in pumps - Google Patents

Abstract

850,469. Centrifugal pumps. NASH ENGINEERING CO. May 24, 1957 [Jan. 25, 1957], No. 16573/57. Class 110 (1). A pump comprises a main impeller; a liquidring compressor rotor; a casing defining a central inlet and a peripheral volute discharge for the impeller, a centrally-located rotor inlet and rotor discharge and a substantially elliptical working chamber for the rotor; a connection between a point in the vicinity of the impeller inlet and the central portion of the rotor to deliver air and vapour from the impeller to the rotor for compression and condensation of liquid; and an intermediate impeller having a central inlet connected to the rotor discharge and positioned to discharge peripherally into the volute discharge. In the aircraft fuel pump shown, liquid fuel entering at 16 is acted on by impeller blades 17 and discharged to a volute 18. Gas and vapour in the liquid are centrifugally separated from the liquid by the blades 17 and discharged to an annular collecting groove 20, whence they are drawn through a passage 22 to the inlet port 24a of one lobe of a double-lobe liquid-ring compressor. The compressed gas and vapour are delivered through a discharge post 24b to an annular space 25. Gas and vapour collecting at the highest point of the suction line leading to the inlet 16 and also collecting at local restriction in the suction line caused by a fitting such as a valve, heat exchanger or strainer are withdrawn from these two places through piping leading to the inlet port (not shown) of the second lobe of the liquidring compressor and delivered through a discharge port to the annular space 25. In the course of compression in the two lobes of the liquid-ring compressor, the vapour is condensed and the gas is re-absorbed in the liquid of the liquid ring, so that the fluid delivered to the space 25 is substantially all liquid. This liquid is then delivered by centrifugal blades 26 to the volute 18, where it joins the liquid delivered by the blades 17. The blades 17 and 26 and the blades 23 of the liquid-ring compressor are carried by a common impeller. The liquid ring is continuously replenished by liquid passing through a hole (not shown) from the volute 18 to an annular chamber 50 surrounding the liquid-ring compressor, from which it passes through holes such as 55 (not shown) to the two lobes of the compressor. To ensure the supply of liquid for this purpose, a reservoir may be connected to the volute 18 or the chamber 50. Specifications 648,546 and 720,526 are referred to.