Centrifugal pumps are a subclass of dynamic, asymmetric, work-consuming centrifugal machines. Centrifugal pumps are used to transport fluids by converting rotational kinetic energy into hydrodynamic fluid flow energy. Rotational power usually comes from a motor or electric motor. Fluid enters the pump impeller at or near the axis of rotation and is accelerated by the impeller, flowing radially outward into the diffuser or volute (casing) from which it exits.
Typical applications of centrifugal pumps include pumping water, sewage, oil and petrochemicals. A centrifugal fan is commonly used to make a vacuum cleaner. The inverse function of a centrifugal pump is a water turbine, converting potential energy from water pressure into rotational mechanical energy.
Like most pumps, a centrifugal pump converts rotational energy, often from a motor, into energy from a moving fluid. Part of the energy is converted into the kinetic energy of the liquid. The fluid enters axially through the casing tube, is captured by the impeller blades, and then rotates tangentially and radially outward until it exits through all circumferential portions of the impeller to the diffuser section of the casing. The liquid gains speed and pressure as it passes through the impeller. The annular diffuser or volute portion of the casing slows the flow and further increases the pressure.
In mining or oil sands operations, foam is generated to separate rich minerals or bitumen from sand and clay. Foam contains air which can clog conventional pumps and cause loss of primer.
Throughout history, the industry has developed various ways to address this problem. In the pulp and paper industry, holes are drilled in the rotor. The air exits the rear end of the turbine and is pushed back into the suction tank by a special ejector. The impeller can also contain special small blades between the main blades called split or secondary blades. Some pumps may have a large eye, an inductor, or recirculation of pressurized foam from the pump outlet to the inlet to break up bubbles.
In any industrial facility where pumps are used, energy costs are invariably one of, if not the most important, component of pumping systems. However, industry trends seem to favour centrifugal pumps over other pumping systems when it comes to energy savings.
Another advantage of the centrifugal pump is its capacity. The impellers in the pump move in a smooth rotating motion that ensures an even pressure throughout the liquid.
There's a reason people continue to turn to centrifugal pumps for long-term liquid handling applications. This is because they have a proven track record of reliability. They tend to be more robust in construction than piston pumps, which increases their lifespan.
Centrifugal pumps generally require less maintenance than positive displacement pumps, although both have relatively simple maintenance procedures.
A centrifugal pumps design takes up significantly less space than piston pumps with the same performance. If you want a more efficient centrifugal pump, just increase the impeller speed as well as the inlet and outlet diameters.