Centrifugal Pumps are one of the most important equipment used in process industries. So learning about centrifugal pumps is very essential for chemical engineers. So here is the guide related to it. Enjoy and share your feedback in the comments.
Introduction of Centrifugal Pumps
What is a Centrifugal Pumps
A centrifugal pump is a type of pump that uses a rotating impeller to move water or other fluids by using centrifugal force. The fluid is moved by the impeller, which is a rotating component that has vanes on it. As the impeller rotates, it imparts energy to the fluid, causing it to move outward from the center of the pump. This movement of the fluid creates a pressure differential, which helps to move the fluid through the pump and out to the desired location. Centrifugal pumps are commonly used in a wide variety of applications, including irrigation, water treatment, and industrial processing.
Figure 2 Centrifugal Pump Model
Working of Centrifugal Pumps
A centrifugal pump works by using a rotating impeller to draw water into the pump and then discharge it at a high velocity. The impeller is driven by a motor, which can be electric, hydraulic, or engine-powered.
When the impeller rotates, it creates centrifugal force, which draws water into the center of the pump and then pushes it outward through the discharge port. As the water is expelled from the pump, it creates a low pressure zone at the inlet, which causes more water to be drawn in. This process continues as long as the pump is running, resulting in a continuous flow of water.
Centrifugal pumps are designed to handle a wide range of flow rates and pressures, and they can be used to pump liquids of different viscosities and densities. They are relatively simple in design and easy to maintain, which makes them a popular choice for a wide variety of applications.
Types of Centrifugal Pumps
Types of Centrifugal Pumps Based on Flow Pattern
- Radial flow pumps: These pumps have impellers that are designed to move the fluid in a radial direction, meaning that the fluid flows outward from the center of the pump.
- Mixed flow pumps: These pumps have impellers that are designed to move the fluid in both a radial and an axial direction. The fluid is first accelerated radially outward by the impeller, and then it is forced to flow in an axial direction through the diffuser.
- Axial flow pumps: These pumps have impellers that are designed to move the fluid in an axial direction, meaning that the fluid flows parallel to the shaft of the pump. Axial flow pumps are commonly used for low-pressure, high-volume applications.
Types of Centrifugal Pumps Based on Stages
- Single stage pumps: These pumps have only one impeller and are used for low-pressure applications.
- Multistage pumps: These pumps have multiple impellers and are used for high-pressure applications.
- Submersible pumps: These pumps are designed to be submerged in the fluid that they are pumping and are commonly used for sewage and drainage applications.
- Self-priming pumps: These pumps are able to draw the fluid being pumped from a level below the pump, making them useful in applications where the fluid is not always present at the inlet of the pump.
Major Parts of Centrifugal Pumps
- Impeller: This is a rotating component that is responsible for imparting energy to the fluid being pumped. The impeller is typically made of cast iron, bronze, or stainless steel.
- Casing: This is the outer shell of the pump that encloses the impeller and other internal components. The casing is typically made of cast iron or steel.
- Shaft: This is a long, cylindrical rod that connects the motor to the impeller. The shaft is typically made of stainless steel or other corrosion-resistant materials.
- Mechanical seal: This is a device that prevents leaks by sealing the gap between the rotating shaft and the stationary pump casing.
- Suction and discharge ports: These are openings in the pump casing through which the fluid is drawn in (suction port) and expelled (discharge port).
- Motor: This is the power source for the pump, which can be electric, hydraulic, or mechanical.
- Base plate: This is a flat, solid surface that the pump is mounted on, which helps to keep the pump stable and level.
- Volute: This is a curved channel that surrounds the impeller and helps to guide the flow of fluid.
- Discharge pipe: This is a pipe that carries the fluid from the pump to the desired location.
- Coupling: This is a device that connects the motor and the pump shaft, allowing them to rotate together.
- Wear ring: This is a thin, circular ring that is placed around the impeller to reduce wear and prevent damage to the pump.
Types of Impellers
- Radial flow impellers: These impellers have a series of vanes that radiate out from the center of the impeller and are designed to create a flow that is perpendicular to the shaft of the pump.
- Mixed flow impellers: These impellers have a combination of radial and axial flow elements and are designed to create a flow that is both perpendicular and parallel to the shaft of the pump.
- Axial flow impellers: These impellers have a series of vanes that are aligned parallel to the shaft of the pump and are designed to create a flow that is parallel to the shaft.
- Vane impellers: These impellers have a series of vanes that are attached to a central hub and are designed to create a flow that is both radial and axial.
- Scroll impellers: These impellers have a helical vane design and are designed to create a flow that is both radial and axial.
- Turbo impellers: These impellers have a series of blades that are mounted on a disc and are designed to create a flow that is both radial and axial.
- Double suction impellers: These impellers have two sets of vanes that are mounted on opposite sides of the impeller and are designed to create a flow that is both radial and axial.
Types of Casings in Centrifugal Pumps
- Volute Casing: The volute casing is the most common type of casing used in centrifugal pumps. It has a spiral shape that helps to evenly distribute the flow of the pump and reduce pressure losses.
- Double Suction Casing: Double suction casing is used in pumps where the flow rate is high and the head is low. The casing has two inlets, one on each side of the impeller, which allows the pump to draw in a larger volume of fluid.
- Split Casing: Split casing pumps are used in high-flow, low-pressure applications. The casing is split in half horizontally, allowing the impeller to be removed without disassembling the entire pump.
- Barrel Casing: Barrel casing is a type of casing that is used in pumps with high pressure and low flow rate. The casing has a cylindrical shape and is usually made of metal.
- Tunnelling Casing: Tunnelling casing is used in submersible pumps that are used in underground or underwater applications. The casing is designed to withstand the pressure of the surrounding soil or water and protect the pump from damage.
Applications of Centrifugal Pumps
- Water treatment: Centrifugal pumps are used to transfer water from one location to another, such as in a water treatment plant where water is pumped from a river or other source into a treatment facility and then distributed to homes and businesses.
- Agriculture: Centrifugal pumps are often used in irrigation systems to transport water from a well or other water source to fields where crops are grown.
- Industrial processing: Centrifugal pumps are used in various industrial processes, such as petrochemical refining, papermaking, and power generation, to transfer liquids and gases.
- Construction: Centrifugal pumps are used in construction to move water and other fluids to and from the construction site.
- Firefighting: Centrifugal pumps are used in firefighting to pump water from a source (such as a pond or river) to the site of a fire.
- Flood control: Centrifugal pumps are used in flood control systems to move excess water from low-lying areas to higher ground or to a treatment facility.
- Domestic use: Centrifugal pumps are also used in domestic settings for tasks such as boosting water pressure in a home or garden irrigation.
