How does the slurry pump work?
Using the conversion of rotational kinetic energy into the hydrodynamic energy of the fluid flow, centrifugal Slurry Pumps motivate fluid flow along pipelines. Pump rotation, and thus rotational energy, is typically created by the electric motor driving the Pump shaft through a V-belt drive. The fluid enters axially into the eye of the Pump impeller, which by its rotation acts tangentially and radially on the fluid. The fluid is accelerated by the impeller gaining velocity and pressure, flowing radially outward into the casing, decelerating but building pressure. Being pressurized, it then exits the volute. The displaced fluid in the Pump head is replaced by atmospheric pressure and static pressure acting on the fluid in the sump, pushing it into the impeller.
The speed of the Pump is regulated by the ratio of the transmission plus, in some cases, the use of a variable frequency drive to tune the speed for a more exact duty. Care needs to be taken not to use high turn-down ratios, which result in the loss of power. Head or more specifically total dynamic head, which is the sum of static, friction and pressure heads, is used to find the speed head. Calculated water head is corrected (HR) using the d50 of the particles being pumped, the percent solids by volume. Horsepower is calculated as work done and thus includes the fluid specific gravity. Reference should always be made to the manufacturer’s curves to ensure the Pump is operating in the most efficient zone.
It should be noted that this design of Pump, unlike a self-priming positive displacement Pump, does not actually suck the fluid into the casing. As discussed above, the fluid flows into the Pump based on atmospheric pressure and the height of fluid in the vessel (14.5 psi or 33.5ft.hd. [10mhd] + the height to water level in the Sump).
Other factors affect the performance of the Pump, most important of which is the Net Positive Suction Head (NPSH), which is not only an equipment issue but a system issue. NPSHA is a measure of how close to vapor pressure the fluid becomes. NPSHR is head value on the suction side that is required to keep the fluid from cavitating. Heated solutions are particularly prone. Significant damage can occur to the impeller and bearings when a Pump is cavitating.
The reverse function of the centrifugal Pump is as a water turbine converting potential energy of water pressure into mechanical rotational energy. Examples of this are in tailings disposal down long inclines to ponds. Special builds are required.
Lining materials vary and are typically selected based on the materials to be handled and any chemistry present. Most sand sized materials <5mm (4mesh) can be handled effectively by the use of the high-quality natural rubber compound liners. Gravel should be handled by hard metal Pumps, such as Ni-Hard or Hi-Chrome (27%).
We are slurry pump manufacturers. Please feel free to contact us if you are interested in our products.