Centrifugal pump

摘要

A multi-stage centrifugal pump has a shorter shaft length compared to conventional multi-stage pump with the same number of impellers on the drive shaft (e.g. about 17-28% shorter length). The shorter length is obtained by utilizing first and second annular slide bearings. Adjacent at least one end (and preferably both) of a rotatable elongated shaft of the pump (which mounts the impellers) within a casing the first slide bearing is mounted to a stationary end structure while the second slide bearing is mounted to the shaft for rotation with it. A plurality of O-rings may be provided to mount the second slide bearing to the shaft. A sleeve with shoulder engaging opposite ends of the second slide bearing may be provided, and the slide bearings may have a clearance of about 0.04-0.1 mm between them, with a lubricant in the clearance. A labyrinth seal is typically provided in the most remote shoulder. The slide bearings are of silicon carbide or a similar material, and have a length (in the dimension of elongation of the shaft) of about 10 cm or less. The impellers may be mounted to the shaft without keys by providing polygonal protrusions concentric with the shaft formed on the impellers and cooperating with similarly shaped polygonal recesses in an adjacent impeller.