GB1213163A - Centrifugal pumps - Google Patents

Abstract

1,213,163. Centrifugal pumps. ENGLISH ELECTRIC CO. Ltd. March 27, 1968 [March 28, 1967], No. 13978/67. Heading F1C. [Also in Division F4j A centrifugal pump for pumping molten metal from a furnace comprises a hollow impeller held with its lower end dipping into the metal 23 and spun by a motor 11 from its upper end, the impeller consisting of an upper portion comprising a tubular lining 17 of refractory material, an insulating layer 27 surrounding the lining, and a metal sheath 26 surrounding the insulating layer for strengthening the upper portion, and a lower portion consisting of a self-supporting tube 20 of refractory material. The separate tubes 17, 20 may be replaced by one continuous tube of refractory material. Radial vanes 24 may be provided to help start rotation of the metal entering the impeller. Centrifugal force on the column of molten metal within the impeller causes it to rise along the inner wall of the impeller until it is discharged through outlet ports 18 into an annular trough 29, from which it passes via a spout 30 into a channel 31. If the liquid level in the trough 29 rises above a weir 34, the excess liquid spills back in to the pool 23. Instead of or in addition to the weir 34, a float valve in the trough 29 may control the speed of the motor 11. The trough 29 and channel 31, at least at parts liable to be contacted by molten metal, are of refractory material. The motor 11 is driven by compressed air, the exhaust from the motor passing via openings 10A to cool the sheath 26. Where it is necessary to control the atmosphere in contact with the molten metal, the whole pump may be enclosed in a gas-tight vessel which is evacuated or filled with a desired atmosphere.