What is centrifugal pump? The Essential Parts and Working Principle of a Centrifugal Pump.

What is centrifugalpump? The Essential Parts and Working Principle of a Centrifugal Pump.

What is Centrifugal Pumps?

Centrifugal pumps are devices that are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an electric motor or steam turbine (in case of turbine-driven feedwater pumps). Centrifugal pumps are used in more industrial applications than any other kind of pump. The most common centrifugal pump is the volute pump.

 

 

Main Parts of a Centrifugal Pump

 

Centrifugal Pump - min Each centrifugal pump is made of hundreds of parts. There are a few components that virtually every centrifugal pump has in common. These components can be subdivided into the wet end and the mechanical end. The wet end of the pump includes those parts that determine the hydraulic performance of pump. The two primary wet ends are the impeller and casing. In some cases the first radial bearing can be water lubricated. In this case also bearing can belongs to wet ends. The mechanical end includes those parts that support the impeller within the casing. The mechanical end of the pump includes the pump shaft, sealing, bearings and shaft sleeve. These components are designed to perform specific tasks:

 

Impeller - Impeller is a rotor used to increase the kinetic energy of the flow.

Casing (Volute) - The casing contains the liquid and acts as a pressure containment vessel that directs the flow of liquid in and out of the centrifugal pump. The volute is a curved funnel that increases in area as it approaches the discharge port. The volute of a centrifugal pump is the casing that receives the fluid being pumped by the impeller, slowing down the fluid’s rate of flow. Therefore, according to Bernoulli’s principle, the volute converts kinetic energy into pressure by reducing speed while increasing pressure. Some centrifugal pumps contain diffusers. A diffuser is a set of stationary vanes that surround the impeller. The diffuser directs the flow, allows a more gradual expansion and therefore increases the efficiency of the centrifugal pump.

Shaft (Rotor)- The impeller is mounted on a shaft. Shaft  is a mechanical component for transmitting torque from the motor to the impeller.

Shaft sealing- Centrifugal pumps are provided with packing rings or mechanical seal which helps prevent the leakage of the pumped liquid.

Bearings - Bearings constrain relative motion of the shaft (rotor) and reduce friction between the rotating shaft and the stator. There are at least 5 common types of bearing, each of which operates on different principles:

 

1-Plain bearing

2-Rolling-element bearing

3-Jewel bearing

4-Fluid bearing

5-Magnetic bearing

 

 

Working principle of centrifugal pump

 

A centrifugal pump is a rotodynamic pump that creates fluid flow by using a rotating impeller to impart energy. It operates as a reverse of an inward radial flow reaction turbine. The Francis turbine and centrifugal pump share a similar design; however, the fluid flow in the latter is opposite. The centrifugal pump operates on the principle of forced vortex flow, means that as you rotate a certain amount of liquid by an external torque, the pressure rises in that liquid. Which give enough centrifugal force to lift liquids from a lower level to a higher level. At any point in the rotating liquid, the increase in pressure head is proportional to the square of the liquid's tangential velocity there.

 

i.e., Rise in pressure head = v^2/2g or w²r²/2g

 

As a result, the rise in the pressure head will be greater at the outlet of the impeller where the radius is greater, and liquid will be discharged there with a high-pressure head. The high-pressure head of this liquid can be used to lift it to a high level.