Patent ID: 6106230
Filing Date: 2000-08-22
Classification: F04D

Abstract:
A method of increasing the flow rate at BEP for a radial flow pump of selected parameters said pump including a main casing and a front casing or throat bush having an inlet diameter D.sub.1 and an impeller having an outer impeller diameter D.sub.2 and an inlet diameter substantially the same as the inlet diameter of the front casing or throat bush, the method including the steps of:(a) replacing the impeller with a modified impeller, said modified impeller including a front shroud and a rear shroud the shrouds being spaced apart so as to form a plurality of passageways therebetween which are separated by a plurality of impeller blades the impeller having an outer diameter D.sub.2 and an inlet diameter D.sub.1, each passageway having an inlet portion with a passageway inlet having a width B.sub.1 an outlet portion having a passageway outlet B.sub.2 and an intermediate portion between the inlet and outlet portions; in the inlet portion the front shroud being curved away from the rear shroud at a passageway angle .beta. so that the passageway outlet width B.sub.2 is less than the passageway inlet width B.sub.1 ; and(b) replacing the front casing or throat bush with a modified front casing or throat bush having an inner wall which is complementary to the wall of the front shroud of the modified impeller while retaining the same main casing.