Patent GB-967971-A (GB)
Title: Impeller pumps
Inventor: ANDERSON HAROLD HENRY
IPC: F22D11/02
Filed: 1962-05-17
Abstract: 967,971. Centrifugal pumps. HARLAND ENGINEERING CO. Ltd. May 13, 1963 [May 17, 1962], No. 19082/62. Heading F1C. An impeller pump has an annular flow constriction 7, Fig. 1, defined by a balance disc 4 carried by the impeller shaft 1 and a fixed thrust face 6, a liquid flow path 11 connecting the inlet 8 of the constriction 7 to the high pressure side of the pump to leak-off liquid radially through the constriction 7 to hydraulically balance the axial impeller thrust, an annular chamber 13 into which liquid from the constriction 7 is discharged, an inlet 22 connected to a source of cooling liquid and opening into the chamber 13 adjacent the discharge 12 of the constriction 7, and an outlet 15 from the chamber 13 connected to a de-aerator. The cooling liquid, from an external source or from the inlet side of the pump, is supplied to an annular chamber 17 through an inlet 16, Fig. 4, adjacent the outlet 15. A second, diametrically opposite, inlet and outlet set, partly shown in the developed view in Fig. 4, is provided. Both sets communicate with a passageway 14 provided with partition walls 25. The cooling liquid in the chamber 17 flows through an annular opening 18 and is centrifugally fed through an annular passage 19 to the inlet 22 into the chamber 13. A gland 3 on the opposite side of casing 2 to the impeller (not shown) prevents leakage to oil lubricated bearings (not shown). In a boiler feed system, Fig. 5 (not shown), water from a de-aerator is passed through an optional boost pump to the main pump provided with the cooling and balancing arrangements. The main pump receives water at, say, 300‹F. and low pressure and delivers it to the boiler at high pressure, for example 3000 p.s.i. The cooling water, supplied from the inlet side of the main pump, prevents an excessive rise in temperature of the balancing water, in the zone of the constriction 7, when the boiler demand ceases. The exhausted cooling and balancing water is fed back to the deaerator. In an alternative boiler feed system, Fig. 6, a boost pump 40, provided with the balancing arrangement, draws water from a de-aerator 42 and delivers it at about 800 p.s.i. to a heater 45, wherein it is heated to 450‹- 500‹F. A main pump 46, provided with the balancing and cooling arrangements, receives this water and delivers it, at 450‹-500‹F. and 3000 p.s.i., through a line 56 and a manually operated stop valve 57 to the boiler. Sealing water is supplied through line 51 to an annular chamber 52 in the shaft glanding and some leaks along the shaft into a chamber 50 to provide the cooling. The balancing and cooling water is returned to the main stream at the inlet side of the main pump 46 through a non-return valve 55. However, when the boiler demand ceases and the temperature within chamber 50 exceeds a predetermined value, as sensed by an element 61, the latter causes a valve 60 to open to cause the water in chamber 50 to pass through a line 58 and constriction 59 into the de-aerator 42, resulting in a pressure loss in the chamber 50 with consequent increase in cooling water flow therethrough. Additionally, there will then be a power loss within the system.