Sludge and Slurry represent a challenge for any pumping application, the thick and abrasive nature of these fluids means selecting the right sort of pump is crucial. Here are the four main varieties with their pros and cons.
It’s most common to use positive displacement pumps when dealing with Slurry, but where you have low viscosity sludge that only contain small sized solids, then you could consider Centrifugal Pumps. The advantages with this type of pump are that it requires less power and will generate less pulsation. The main disadvantage is that Centrifugal Pumps have a higher shear rate. Shear rate is the change of velocity at which one layer of fluid passes over another. A simple example of this would be spreading butter on bread. The level of the liquid (butter on the knife) is moving relative to the adjacent layer (butter on the bread). In regards to Slurry it is desirable to keep them concentrated to move them through the pump but where these shear forces are higher, more surface area is created which dispersed the solids within the slurry, making it more difficult to de-water.
This type of pump is very simple in its design and use, it is powered by compressed air and operates on a single diaphragm. This makes it very easy to control the speed of the pump and as such you will have a fairly reliable and consistent output. Using compressed air does mean that this type of pump has a higher pulsation rate and can be costly if you don’t already have a large air compressor.
As a helical rotor is turned, slurry makes its way through the pump by sequence of small cavities left between the rotor and the stator. The advantage of this design is that it imparts very minimal shear on the sludge and generates low pulsation rates. The disadvantage of this type of pump is that maintenance and repair can be difficult, and they tend to be quite space consuming.
A good Pump option where you have high viscosity fluid, a Rotary Lobe Pump works in the principle of a pair of rotors both rotating evenly, which creates a vacuum on the priming side of the pump, this vacuum draws the slurry into the pump chamber. This is very similar in design to an external gear pumps, but the lobes themselves do not make contact. This pump option have minimal pulsation and minimal shear, and as the rotors rotate in opposite directions without contact they do not wear as quickly.
What We Offer
B&B are sub-contract manufacturers of a wide range of components for slurry pumps. Working from customer drawings we have experience of making rotors, drive shafts, flanges and much more. We also provide HVOF Coatings which can extend pump components for abrasive slurry materials. Get in touch for both new and replacement components for your slurry pumps.