Symmetrical radially split centrifugal multistage thrustless pump

Abstract

A multistage centrifugal pump having a barrel-type, radially split casing comprises a rotor including oppositely directed first and second impeller groups having equal numbers of impellers, all fixed to a common rotating shaft. Process fluid entering the pump is divided into two equal flows that are directed respectively to inputs of the first and second impeller groups, the two flows being thereby equally pressurized by the impeller groups, and then combined into a common pump outlet flow. The two impeller groups thereby function as substantially identical pumps operating in parallel that apply equal and opposite, cancelling axial thrusts to the rotor. In embodiments, the thrust cancellation of the two impeller groups is sufficient to obviate any need for thrust compensation mechanisms. The centrifugal pump can be a BBor BBpump. Residual thrust due to a slight asymmetry between the impeller groups can axially stabilize the rotor.