Slurry Pump
WH14AAAAAA0EN_04D.DOC JAN 04-W08
Desccription of operation
4/4
Hydraulic efficiency is a function of hydraulic turbulence - the more turbulence, the less
efficiency. In slurry pumping, a high level of efficiency is therefore important.
Little hydraulic turbulence is formed at BEP and the abrasion is chiefly of a sliding nature,
since the differential pressure is low when the slurry passes through the impeller and
pump casing. The rate of abrasion is low and the wear is spread evenly over the surfaces.
The rasping wear or high-pressure wear that occurs between the impeller and suction side
liner is lower, since the evenly distributed hydraulic pressure reduces recirculation.
When the full capacity of the pump is not used and its efficiency is less than at BEP,
hydraulic turbulence occurs and the solid particles in the slurry strike and rasp the impeller
and pump casing. This causes local wear damage and the service life of these
components is severely shortened. At the inlet to the impeller the slurry's flow angle is not
the same as the pump vane angle, which gives rise to turbulence and results in
recirculation of slurry in the channel. At the pump casing nose the flow from the impeller
does not harmonize with the shape of the casing, causing turbulence to occur immediately
after the pump casing nose.
In the worst case, oversized pumps which do not operate at BEP result in bearing
breakdown, shaft fracture and unevenly worn inlet and pump casing liners with deep wear
marks at the casing nose.
4.4 Choice of pump size
For preference, choose the pump size which operates as close as possible to the pump's
best efficiency point (BEP).
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