Dewatering: Thickening, Filtering, CCD, Water Treatment & Tailings Disposal

Dewatering: Thickening, Filtering, CCD, Water Treatment & Tailings Disposal

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Slurry pump too large for application - speed reduction (2 replies)

3 years ago
CA 3 years ago

We have an application that requires a 1.5" x 1" slurry pump.

However, the spare pumps that we have available are a Warman 3/2 and a Flowserve 2.5/2.  We would like to try to reduce the throughput of these pumps by changing out the pulleys and/or using a VFD for motor control.  

Does anybody know if, for example, reducing the impeller speed by half results in 50% less slurry pumped?   i.e.  is the pump volume a 1:1 relationship with speed or is it more likely to follow a curve?

Are there any pitfalls to doing this?  We have very low head requirements.  

Thanks for your input.

3 years ago
SmartDog 3 years ago

Centrifugal pumps have performance curves based on their dimensions, installed impellers, available suction head, operating speed, system output configuration.  The curves are not linear to any of these factors.  Also similar pumps, but with slightly different dimensions can have different performance curves.  To determine if a pump will perform in a particular duty you need to examine the curve (which is normally supplied by the vendor) for that particular pump.  The vendor supplied curve is usually for water and the slurry viscosity and density also need to be figured in.  

Todd H
3 years ago
Todd H 3 years ago

As mentioned you need the pump curve to know the impact of changing speeds, it is not a linear relationship except for a small portion of the curve (typically).  You can do a couple of other things:

  1. You can change the impeller type to pump less - most pumps have a series of impellers that can be used - need performance curves
  2. You can use these bigger pumps but install a branch to recirculate slurry back to the feed tank - basically bleed off the excess
  3. You could throttle the pump with a valve in the slurry feed line, this is not a great option


Todd Harvey - Global Resource Engineering

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