Pulp pumps are used for transporting mixtures of liquid and solid components (e. g. fibrous materials in the pulp and paper industry).
Pulp pumps are usually horizontal, single-flow, single-entry centrifugal pumps in back pull-out design. They are especially designed for handling fluids with non-NEWTONian flow properties (see NEWTONian liquid) as well as the high air contents of pulps (see Pulp pumping). See Fig. 1 Pulp pump
Large inspection holes facilitate a quick and easy removal of any clogging. Special impeller types are fitted which match the type of pulp and the pump application. These include open impellers, which can be combined with a side channel impeller if the pulp is hard to pump, and free-flow impellers (also see Torque flow pump).
Free-flow impellers are used if the pulps to be pumped (also see Pulp pumping) are contaminated or if the mixing effect of the free-flow impeller creating a vortex is advantageous for a particular process.
A wear plate, which is easy to replace, protects the pump casing against wear on the suction side. The pump shaft is protected against corrosion and wear at the wetted end by means of a shaft seal which prevents the shaft from any contact with the fluid pumped. The shaft seal is either a gland packing or a mechanical seal, both of which are supplied with a barrier fluid.