Centrifugal pump is an important familiar pump that is used for transferring fluids from one place to another. A rotating impeller is used to move the fluids by applying centrifugal force. This type of pump gets popular to move fluids from one location to another in various industrial applications such as chemical industries, petroleum industries, mining industries, power generation plants, agricultural and other purposes.
Centrifugal pump operates the fluids with large quantities at very high flow rates. Besides, it can control the flow rates over a wide range for different purposes.
Centrifugal pumps are used for transferring fluids with relatively lower viscosity, such as light oil or water. It requires more horsepower on a centrifugal pump for more viscous fluids to run. A positive displacement pump is generally used for transferring fluids with higher viscosities which helps to reduce energy consumption.
Operating Principle of Centrifugal Pumps
Now, we want to discuss the operating principle of centrifugal pumps. This pump creates a centrifugal force to flow or raise a fluid from a lower energy level to a higher energy level by a straightforward mechanism. This pump converts the rotational energy from a motor into the kinetic energy in a moving fluid.
The two main instrumental parts of this pump responsible for performing this task are the impeller and the casing. These two parts of this pump are called the wet end. The impeller portion is the rotating part of this pump and the casing is the airtight path that surrounds the impeller.
The fluid enters into the casing of this pump and falls on the eye of the impeller, and rotates quickly on the direction of outward until it exists the impeller through the volute part of the casing. The fluids gain pressure and velocity during the time of transfer from the impeller portion to the casing portion.
The Different Parts of Centrifugal Pumps
A centrifugal pump has various parts that (e.g. bearing, shaft, etc.) maintain the mechanical structure of the pump, and others (casing and impeller) maintain the hydraulic function of the pump.
Impeller
The impeller is an important rotating part of this pump. This part is attached to a shaft that is connected to an electric motor. The motor can rotate the impeller part. There exist many shapes and sizes of the impeller for different applications and the properties of the pumped liquids and are composed of many backward-curved blades.
The impellers can be made from different types of materials based on the various properties of the pumped liquid. It must be remembered that all impellers must be dynamically balanced before being installed on the pump body.
Casing
This part is a completely air-tight passage that surrounds the impeller part. This part of the pump has the ability to convert the kinetic energy of the water coming from the outlet portion of the impeller into a pressure head portion before leaving the casing.
The casing of centrifugal pump is generally two types:
Volute
It is a spiral-type casing in which the flow of the liquid gradually increases. It helps to increase the pressure of the fluid and decreases the velocity of the fluid.
Diffuser
There are several guide blades around the impeller. These blades are situated on a ring-type structure called a diffuser. The design of this part helps to increase the pressure and decrease the velocity of the fluid. Water can move through the surrounding casing after passing the guide blades, which usually remain connected with the impeller portion.
Shaft
The shaft is a very important central part of this pump because impellers, shaft sleeves, and bearings, are installed with this part. The mechanical energy from the motor is given to the shaft which delivers this power to the impeller to rotate.
Shaft Sleeve
This part is generally found in single-stage pumps. It is a hollow metal cylindrical tube-type part, which is installed over the shaft assembly to safeguard it in a corrosive environment.
Bearings
There exists many bearing of this pump that holds the rotor of the shaft rotor in the proper alignment with the fixed parts under the action of axial and radial loads.
Sealing Arrangements
This arrangement seals the rotating shaft as it passes the fluids through the non-rotating casing of the centrifugal pump. It helps to decrease the fluid leakage problem to the atmosphere or the entrance of air from outside and prevents the wear of the sealing faces.
Uses of Centrifugal pump
There exist many fields where this pump is generally used which are given below:
Centrifugal pump is used in wastewater treatment plants, municipal plants, flood protection systems, and irrigation purposes.
This pump is used in the sugar refinery industry, beverage industry, petrochemical industry, and medicinal industry.
This pump is used in the energy and oil industry for pumping oil, slurry, mud, refining process, and power plant processes.
This pump is used in industrial sectors for proper ventilation, heating purposes, air conditioning, pressure boosting purposes, boiler feed water circulation, and fire security sprinkler purposes.
References
1.Tuzson, J. (2000). Centrifugal pump design. John Wiley & Sons.
2.Pumps, S. S. (2010). Centrifugal pump handbook. Butterworth-Heinemann.
