| 摘要 |
<p>1,006,365. Priming centrifugal pumps. ENGLISH ELECTRIC CO. Ltd. Oct. 14, 1963 [Oct. 14, 1962], No. 38853/62. Heading F1C. An hydraulic pump or reversible pumpturbine includes means for injecting water into the suction tube with a substantial tangential component of velocity adjacent the wall of the suction tube below and adjacent the impeller so as to generate a vortex having a substantial peripheral velocity during priming of the pump or of the pump-turbine in operation as a pump. Pumping operation of a pump or pumpturbine is started by a procedure which is substantially the same as that described in Specification 1,006,299, but the means for controlling the power absorption comprises baffles 38, Figs. 2 and 3, defining slots 39 through which water can be directed from an annular chamber 37 to produce a vortex in the suction tube 20. The water is supplied from a pressure source, such as the spiral casing 17, through a pipe 50 provided with a valve. After the pump has been run up to synchronous speed with the impeller empty as described in Specification 1,006,299, the valve in the delivery pipe is opened to allow water to flow from the delivery pipe into the spiral casing 17, the adjustable guide vanes 24 remaining shut. The valve in the pipe 50 is then slowly opened to produce a vortex in the suction tube 20. The impeller 11 gradually fills with water, and the displaced air escapes through the pipe 31. During the final removal of the air, the power absorbed by the pump rises rapidly at a rate which tends to be difficult to control. However, the vortex produced in the suction tube 20 by the jets of water issuing through the slots 39 controls the flow and reduces the rate of power rise to an acceptable value. Finally, by gradually opening the adjustable guide vanes 24 the power absorbed is increased to full load. In an alternative procedure, suitable for a pump in which the adjustable guide vanes 24 are omitted, the delivery valve is kept closed until the impeller has been filled with water, and is then opened to increase the power absorbed to full load. In this case, water is not admitted to the spiral casing 17 from the delivery pipe until the impeller has been filled with water. Modifications are described in which the pipe 50 is connected to the delivery pipe downstream of the delivery valve or is connected to the pump casing between the impeller 11 and the adjustable guide vanes 24. The slots 39 may be replaced by circular or other orifices, and the annular chamber 37 may be replaced by a series of short circumferential chambers, or the slots or orifices may be fed direct through separate pipes. The admission of water to the chamber 37 may take place through a ported ring which can be rotated to a position in which its ports register with ports in the stationary structure. In the embodiment shown in Fig. 7, water is fed into the suction tube 20 through the space between the front shroud 13 of the impeller and an annular member 80 which is retracted into the position shown by a series of pistons 81, thereby opening the impeller seal 34. Small fixed vanes (not shown) impart the required swirl to the water.</p> |
