Centrifugal pumps are the most common type of pump. It is popular for both industrial and domestic use and can be found in places such as power generation plants and municipal wastewater treatment plants. Its main purpose it to transport liquids by converting kinetic energy to hydrodynamic energy.
Here is a brief overview of how these pumps work.
Types of Centrifugal Pumps
Many types of centrifugal pumps are available. For example, multistage centrifugal pumps contain two or more impellers. These impellers can be mounted on a single shaft or multiple different shafts.
A type of centrifugal pump is the vertical centrifugal pump. Also known as cantilever pumps, they are designed with a shaft and bearing support system, which allows the volute to stay inside the sump while the bearings stay outside of the sump. As a result, the need for a stuffing box to seal the shaft is eliminated.
Another type of centrifugal pump is the end suction centrifugal pump. It is the most basic type of centrifugal pump and has its suction on one end and the discharge exit located at the top. End suction centrifugal pumps are also made up of an impeller, which increases the velocity of the liquid passing through it. This high velocity is then converted to a high-pressure force.
Components of Centrifugal Pumps
Centrifugal pumps are made up of many different components. Each type of centrifugal pump has their own unique parts. However, there are usually several main components found in all types of centrifugal pumps. These components can be categorized as a wet-end or mechanical-end component.
The wet-end category of a centrifugal pump includes components that affect the pump’s hydraulic performance. This type of performance means the impeller and casing can both be categorized as wet-end components.
The impeller is one of the important components of the pump. Without it, fluids cannot enter the pump and be made to rotate. When the fluids rotate, the impeller is adding a centrifugal force to move it out in the radial directions.
The casing of a centrifugal pump acts as a pressure container and is responsible for directing liquids to flow in and out of the pump. It is designed with increasing area along the flow direction to accommodate the increasing water stream. This pump ensures the velocity of the fluid exiting the pump is not too high. Also, static pressure is increased to overcome any resistance from the system.
The mechanical end category of a centrifugal pump includes components within the casing that work to support the impeller. This casing includes the pump shaft, sealing and the bearings.
The pump shaft, or rotor, is responsible for connecting the pump’s impeller with the motor. It is designed to transmit torque from the motor to the impeller. The shaft’s sealings are made up of packing rings. This sealing is to prevent water leakage as the high-water pressures inside the casing make it prone for water to escape through tiny cracks.
The bearings are another mechanical component of centrifugal pumps. They are responsible for carrying the weight of the impellers. The bearings are fitted at the exit side of the pump since the suction side needs to be kept clear to allow fluids to flow. The impeller is mounted on the bearings in a cantilever-type configuration.
Cooling oil for the bearings are also required in pumps with higher flow rates. Bearings also come in many types, each operating on their own principles. Some types of bearings include plain bearings, jewel bearings, fluid bearings and magnetic bearings.
Centrifugal Pumps in Action
Centrifugal pumps work by converting a rotational energy from a motor to induce a flow or raise the pressure of liquid. When a fluid enters from the suction end of the pump, the impeller catches the fluids and then rotates, making the fluid entering the pump rotate as well.
During this process, the fluid gains velocity and pressure as it leaves the impeller. A diffuser or scroll inside the pump then decelerates the fluid flow, further increasing the fluid pressure.
A unique feature of centrifugal pumps is their ability to provide high flow rates compared to displacement type pumps. The flow rates of fluids from a centrifugal pump also vary depending on changes in the total dynamic head of the piping system. This head allows throttling of the flow rates without causing excess pressure to build up in the piping system, eliminating the need for pressure relief valves.
Centrifugal pumps are one of the most popular types of pumps. They have many applications, and many municipalities use them in wastewater treatment plants. The designs of centrifugal pumps vary depending on the type of pump. However, common pump components, such as the shaft, bearings and casing all work together to induce flow and raise the water pressure.