Method and apparatus for pumping high consistency medium

Abstract

A method of pumping high consistency pulp in form of a plurality of lumps in a pulp and gas containing space with a centrifugal pump having a suction opening communicating with said pulp containing space and a rotor extending through the suction opening into the pulp space including fluidizing the high consistency pulp by the rotating action of the pump rotor; and thereby forming a continuous fluidized pulp containing zone in form of a liquid lock in front of and around the suction opening of the pulp so as to substantially limit the suction action of the pump to the fluidized pulp containing zone and to prevent the gas from flowing in between and past the pulp lumps toward the suction opening. The centrifugal pump for attachment to the wall of the pump containing vessel includes a housing having a suction opening for connection to the wall of the pulp containing vessel and a discharge opening; and an impeller mounted for rotation with the housing, the impeller including a rear plate, at least one pumping vane attached to the rear plate, and a rotor projecting from the impeller toward the suction opening of the pump, the rotor includes at least one blade extending from the impeller through the suction opening beyond the wall of the pulp containing vessel and into the pulp containing vessel by a distance at least equal to the diameter of the suction opening.