Centrifugal Pumps: Its Ten Different Industry Applications

Centrifugal pumps are one of the most common types of pumps used in industry. These pumps use a rotating impeller to create centrifugal force, which helps move fluids through the pump and from one place to another. Given their reliable pump design, Centrifugal pumps are often used to move large volumes of fluid, making them ideal for irrigation, water treatment, and wastewater treatment.

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There are several different types of centrifugal pump designs, including volute-, canned-, and screw-type pumps. Each pump design has its own advantages and disadvantages, so it is essential to consider your needs before choosing a pump design type carefully. Other factors that can impact the type of pump you choose include the viscosity, temperature, and pressure of the fluid you need to move.

Regardless of which type of pump design you choose for your application, there are many benefits to using a centrifugal pump. They are typically easy to maintain, operate at high-efficiency levels compared with other types of pumps, and can be designed to handle liquids containing solids or abrasive chemicals. Additionally, centrifugal pumps are available in various sizes and can be customized to meet your specific needs.

What Are The Common Industrial Applications Of Centrifugal Pumps?

Given their versatility, centrifugal pumps are among the most commonly used pumps in industrial applications. Following are the common industrial applications of centrifugal pumps:

1. Chemical Industry

Centrifugal pumps are commonly used in chemical plants to move fluids around. The fluid is typically moved from one tank to another or from one process to another. Centrifugal pumps can also pump chemicals from one location to another, such as from a storage tank to a reactor. Some common applications of centrifugal pumps in chemical plants include:

• Pumping Liquids: Centrifugal pumps are commonly used to move liquids around in chemical plants. They are often used to transfer fluids from one tank to another or from one process to another.

• Pumping Chemicals: Centrifugal pumps can also pump chemicals from one location to another. For example, they can be used to transfer chemicals from a storage tank to a reactor.

• Pumping Corrosive Fluids: Centrifugal pumps are often used to pump corrosive fluids, such as acids and alkalis. These fluids can damage other types of pumps, so centrifugal pumps are a good choice for these applications.

• Pumping Flammable Fluids: Centrifugal pumps can also pump flammable fluids, such as oil and gasoline. These fluids can be dangerous to pump, so it is essential to select a pump that is designed for these applications.

• Pumping Viscous Fluids: Centrifugal pumps can also be used to pump viscous fluids, such as sludge or pulp. These fluids can be challenging to pump, but the high-pressure application of centrifugal pumps makes it possible to pump them.

2. Irrigation Systems

Centrifugal pumps are used extensively in agricultural applications. They are used for irrigation, transferring water from reservoirs or lakes to fields, and powering farm equipment such as tractors and combines. Centrifugal pumps are also used to spray pesticides and fertilizers on crops. Farmers rely on centrifugal pumps to keep their operations running smoothly. These versatile pumps can handle various liquids, including water, chemicals, and even sludge and sewage. Their simple pump design makes them easy to maintain and repair, essential in rural areas where access to skilled technicians may be limited.

Centrifugal pumps are often used in irrigation systems to move water from lower elevations to higher ones. The pump uses centrifugal force to create a water-lifting action, which helps move the water up and out of the irrigation system. These pumps are often used in conjunction with other pumps, such as submersible pumps, to ensure that the entire irrigation system functions correctly. By using a combination of different types of pumps, farmers and other users of irrigation systems can be sure that their crops will receive the proper amount of water, even during periods of drought or other dry conditions.

3. Water Treatment Plants

Centrifugal pumps are widely used in water treatment plants for various applications. Typically, they are used to move water from one location to another or circulate water within the plant. In some cases, centrifugal pumps are also used to provide high-pressure jetting for cleaning pipes and other surfaces.

• Filtration Applications: Centrifugal pumps are commonly used to move water through filtration systems. They can provide the necessary pressure to push water efficiently and at high flow rates, even against strong resistance from filters and other components in the system.

• Disinfection Applications: In addition to their ability to move large volumes of water with relative ease, centrifugal pumps are ideal for disinfecting water due to their rugged construction and resistant nature against corrosion and wear over time. Many municipal plants rely on centrifugal pumps, particularly when treating wastewater before discharging it into lakes or rivers, where its quality must meet specific standards.

• Saltwater Desalination: Centrifugal Pumps are in saltwater desalination plants. They are used to move large volumes of water through the plant’s filtration system to remove salt and other impurities. This is a critical process for making seawater safe for human consumption or other uses, and centrifugal pumps ensure that the water is adequately filtered and purified.

4. Oil Refineries

Centrifugal pumps are commonly used in oil refineries to transfer liquids between process units. The oil industry typically uses two types of centrifugal pumps:

1. Process Pumps – These pumps are designed to handle highly viscous oils and other liquids with solids content.
2. Utility Pumps – These pumps are designed for general purpose use and can be used to transfer both light and heavy oils.

Utility pumps are typically used to transfer crude oil from storage tanks to the refining process units, while process pumps pump refined products from one unit to another. Both types of centrifugal pumps play an essential role in ensuring an oil refinery’s safe and efficient operation.

Centrifugal pumps are also used in oilfields to transfer crude oil from the wellhead to storage tanks or transport it to pipelines. In addition, centrifugal pumps are used in offshore oil and gas production platforms to transfer liquids between process units and inject chemicals into the production wells.

5. Paper Mills

Paper mills are one of the most common industrial applications of centrifugal pumps. They use centrifugal pumps to move paper stock through the pulping process. The paper stock is a fibrous slurry full of water and other liquids. The centrifugal pump helps to separate the solid fibres from the liquid and then moves the pulp through the system.

Centrifugal pumps are also used in the wastewater treatment process in paper mills. The pumps help move wastewater through the system to be correctly treated and discharged. Pumps are an essential part of paper production, and they play a vital role in ensuring that the manufacturing process runs smoothly.

6. Power Plants

Because centrifugal pumps can handle large volumes of fluid and operate at high pressures, they are ideal for power plants. Centrifugal pumps circulate water in the cooling system, transport fuel oil and lubricating oil, and pump water from the condenser to the boiler. In addition, centrifugal pumps are often used as fire fighting pumps.

The most common centrifugal pump used in power plants is the radial flow pump. Radial flow pumps are very efficient and can operate at high pressures. However, they are not well suited for use in low-pressure systems. Another type of centrifugal pump that is often used in power plants is the mixed flow pump. Mixed flow pumps are less efficient than radial flow pumps but can operate at lower pressures.

Centrifugal pumps are widely used in power plants because they are reliable, efficient, and versatile. In addition, centrifugal pumps can provide years of trouble-free service with proper selection and maintenance.

7. Mining Applications

One of the common industrial applications of centrifugal pumps is mining. Centrifugal pumps are commonly used in mining applications to transfer water from one location to another. They are also used to boost water pressure for various purposes, such as operating hydraulic equipment and washing down mining operations. In addition, centrifugal pumps can be used to create a vacuum, which is often necessary for suction dredging operations.

Centrifugal pumps are also used in the processing of minerals. They can be used to transport slurry, or a mixture of water and solid particles, to a mineral processing plant. Once at the plant, the centrifugal pump can be used to transfer the slurry to various processing tanks and vessels.

Centrifugal pumps are also commonly used in dewatering operations. This is often necessary for mining operations where underground caverns are being excavated. The centrifugal pump can be used to remove water from the excavation site so that the work can proceed more quickly and safely. There are many other uses for centrifugal pumps in the mining industry. For example, they can be used to provide cooling water for machinery, remove sewage and wastewater, and supply water for firefighting operations.

8. Food Processing Plants

Centrifugal pumps are widely used in food processing plants for various applications. Some of the most common uses for centrifugal pumps in food processing include:

• Transferring liquids from one tank to another
• Recirculating liquids during processing
• Cooling liquids during processing
• Transporting liquids to and from storage tanks

Centrifugal pumps offer many advantages over other types of pumps due to their simple pump design, reliability, and ability to pump large volumes of liquid at high pressures. Additionally, centrifugal pumps can be easily customized to meet the specific needs of any food processing application.

9. Military Applications

Centrifugal pumps are widely used in military applications because they can move large volumes of fluids at high pressures. In addition, they are commonly used in aircraft fuel systems, shipboard hydraulic systems, and ground support equipment. Centrifugal pumps are also used in water purification plants and sewage treatment facilities.

There are many different types of centrifugal pumps, each designed for a specific application. Some common types of centrifugal pumps used in military applications include:

• Aircraft Fuel Pumps: These pumps move fuel from the tank to the engine. They are typically made from stainless steel or aluminium and have a high-pressure rating.

• Shipboard Hydraulic pumps: These pumps move hydraulic fluid around a ship. They are usually made from bronze or brass and have a high-pressure rating.

• Ground Support Equipment Pumps: These pumps move fluids around military bases. These pumps have a high-pressure rating and are generally made from solid elements like aluminium or stainless steel.

10. Shipbuilding Industry

Centrifugal pumps are used for bilge pumping, fire fighting, water supply, and fuel transfer tasks. Centrifugal pumps can also be used to transfer sewage and other waste materials from one location to another. In addition, these pumps are often used to create a vacuum environment within a ship’s hull during construction or repairs. The most common applications are:

• Bilge Pumping: Bilge pumping is used to remove water accumulated in the bilge area of a ship. This water can come from rain or waves that have entered the ship. Bilge pumps are also used to remove water that has been spilt on the deck of a ship.

• Fire Fighting: Fire fighting pumps pump water to areas of a ship that are on fire. These pumps are often used with other firefighting equipment, such as hoses and sprinklers.

• Water Supply: These pumps are used to transfer freshwater from the ship’s storage tanks to the various areas of the ship that need it. This water is used for drinking, cooking, and bathing.

• Fuel Transfer: Centrifugal pumps transfer fuel from the ship’s storage tanks to the engines. These pumps are also used to transfer fuel from one tank to another.

• Waste Management: Centrifugal pumps can also be used to transfer sewage and other waste materials from one location to another. These pumps are often used in conjunction with a septic system.

The industrial applications of centrifugal pumps are not restricted to just the ones mentioned above, as they are used in many small and medium industries, given their robust pump design. There would hardly be an industry where centrifugal pumps are not used. If you are also looking for a pump solution, then Centrifugal pumps can prove to be a good choice. You can always go for a customized pump design that suits your application through a reliable pump manufacturer.

Vertical pumps are a special class of pumps used in many different applications from water and utility services to process and exotic applications. They can be used in a range of operating temperatures from low to high, with varying pressures and with many liquids ranging from ordinary water services to corrosive, flammable and even difficult process liquids and chemicals. 

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While there are services in which horizontal pumps are a better option, such as in refineries or petrochemical plants or in boiler feedwater systems, in many applications, vertical pumps can offer an inexpensive, lighter and more compact option. However, many times vertical pumps are specified and used based on purchase costs only. In short, vertical pumps should be used in applications where advantages outweigh disadvantages. This has been the case for a wide range of pumping services. 

This article discusses the types and designs of vertical pumps with special focus on two widely used pumps: vertically suspended (VS) pumps and vertical inline pumps (overhung, OH). It then discusses the most common types and models and explains critical issues related to them. 

Vertically suspended pumps

Vertically suspended (VS) pumps include the subgroups wet-pit and vertically suspended diffuser pump (VS1), which discharges liquid through the pump column. Another type is a volute version of the vertically suspended pump (VS2). Other designs for VS pumps are axial-flow, vertical versions (VS3); volute, line-shaft-driven sump (VS4), which has a separate piping column (parallel to main pump column) to discharge liquid; cantilever sump pumps (VS5), double-casing, diffuser, vertically suspended (VS6); and double-casing, volute, vertically suspended (VS7). For these pumps, discharge liquid should pass through a long column or piping vertically to reach the actual pump package discharge flange. Column static and friction head losses should be carefully considered to avoid underrating the discharge pressure. 

Vertical inline pumps

Vertical inline pumps have been used in small pumping systems. They are known as overhung type 3 or OH3 pumps. OH3 pumps are single-stage overhung pumps with suction and discharge connections that have a common centerline and a bearing housing integral with the pump to absorb pump nozzle loads. The pump’s driver is usually mounted on a support integral to the pump, and the pump and its drivers are usually flexibly coupled. This type of pump is tall, so for stability and good operation, the ratio of the unit’s center of gravity height to the contact surface width is usually limited to 2.5 or 3 (height/width). Generally, stability can be achieved through a good design of the casing (low ratio) or by a permanent external stand.

These pumps are offered in two classes. The first class contains those that can float with the suction and discharge piping, which are used in very small applications and are sometimes treated as piping inlines. The second class contains pumps that are bolted to a pad or foundation. Note that flange loading on the pump can increase if it is elected to bolt the unit down. This option is usually selected when the pump is treated more as equipment rather than piping inline. The close tie to piping may cause difficulties in maintenance; often, a device that allows direct rigging or lifting of the back pullout assembly from outside the motor support with the driver in place is provided for ease of maintenance. Some small pumps in this class are often provided with grease lubrication rather than oil lubrication. 

The temperature in bearings can be a major concern. As a rough indication, bearing housing temperature should not exceed 80°C, and monitoring should be provided. For these small pumps, the driver is usually installed and aligned in the manufacturer’s shop, and the pump is delivered as a complete package to the site.

Other types of vertical inline pumps are rigidly coupled, vertical, inline, single-stage overhung pumps, known as OH4, and close-coupled, vertical, in-line, overhung pumps (OH5). In OH5 pumps, impellers are mounted directly on the driver shaft, which makes them simple and inexpensive to use. 

High-speed inline pumps are usually integral-geared, overhung pumps referred to as OH6. This pump design has a speed-increasing gearbox integral with the pump. The impeller is mounted directly to the gearbox shaft; the gearbox is flexibly coupled to the electric motor driver. Lateral vibration can be a concern with these high-speed pumps. Normally, pumps of this type are thoroughly checked and verified regarding all dynamic situations including lateral and torsional vibrations. Careful dynamic balance is needed. As a rough indication, rotating parts are balanced to a residual unbalance of about 4 to 7 gram × mm or as commonly known in the pump industry, grade 1 (G1) or grade 2.5 (G2.5) (ISO -1). Hydrodynamic radial bearings may be used for such high-speed pumps since a lubrication oil system is needed to feed properly selected oil to the bearings and gear unit.

Selection, operation, maintenance and performance

Vertical pumps are commonly poorly selected or undersized. For any centrifugal pump, rated capacity of the pump should usually be within 80 to 110 percent of the best efficiency point (BEP). Generally, pump manufacturers should provide complete performance curves, including differential head, efficiency, Net Positive Suction Head required (NPSHr), and power, expressed as functions of flow rate. Except for some special pumps such as low specific-speed models in which it is not feasible, curves should ideally be extended to at least 135 percent of flow rate at BEP. 

Usually vertical pumps, particularly those with long shafts, have relatively large inertias in the driver and pump stages and are susceptible to some torsional excitations. Often careful torsional evaluation is needed. Thrust load and thrust bearing configuration need great care because of the weight of components added to operational load in the thrust direction to more stress-fragile and sensitive thrust bearings. Vertical pumps without integral thrust bearings require rigid adjustable-type couplings.

Maintenance of vertical pumps can pose challenges. As a rule, except for VS pumps and integrally geared pumps (such as OH6), vertical pumps should permit removal of the rotor and inner element without disconnecting the suction or discharge piping or moving the electric motor driver.

High vibration and monitoring

Reports of high vibration including frequent failures are common, especially for medium and large VS pumps. These pumps are susceptible to resonant vibration if their separation margins are not verified properly due to their long and large bodies, which are flexible structures. Detailed dynamic evaluation is needed, and as an indication, a 15 to 20 percent margin of separation should be maintained between the natural frequencies and the operating speeds and the first few harmonics.

A medium or large vertical pump package should be provided with a suitable set of monitoring sensors such as vibration probes, accelerometers, electric motor winding temperature and resistance temperature detectors (RTDs). Ideally, each bearing (pump and electric motor) should have X-Y vibration probes and a key phaser with each shaft. RTDs are required for each bearing. Axial displacement probes, ideally two per shaft, are important for reliability and condition monitoring. For small vertical pumps or those in less critical services, some compromise should be reached as many of these sensors would be assessed as too expensive or even unnecessary for such small vertical pumps. 

“Vertical pumps are commonly poorly selected or undersized. For any centrifugal pump, rated capacity of the pump should usually be within 80 to 110 percent of the BEP.”

Flush seals for vertical pumps

Seal selection and flushing seal arrangement are important concerns for any pump including vertical pumps. Dual-flush seals have been used in many pumps including critical vertical pumps. They are commonly used for process pumps or when the pumped liquid is corrosive, dirty, difficult or problematic. As the first option, mechanical seal flushing should be specified for the flushing with the pumped liquid. However, since flushing with such a liquid might reduce the life of the seal over long operating periods, an alternative clean liquid from an external source is usually specified and used for the normal flushing. If the external supply of this clean liquid is interrupted, the pump should be able to continue operation. In other words, the pump should be provided with the automatic switchover, dual-flush system (from clean liquid to pumped liquid) in the event of loss of the clean flushing liquid. Single, simple flushing, which only uses external clean liquid injection, is not a suitable option since in the case of loss of this clean liquid, pumps should be tripped and, consequently, the whole unit, plant or facility would be affected. 

An example is critical vertical pumps in seawater services for many processing plants and facilities. The operation of the plant or facility usually depends on these seawater pumps. Dual-flush (utility water and seawater) connection for mechanical seal flushing should be specified for such a seawater pump. Such a pump system is provided with an automatic switchover dual-flush system (utility and seawater) in the event of loss of utility water. 

The same method can be used for services in liquid hydrocarbon, chemical liquids and others. For example, instead of the flushing with a difficult pumped liquid, a clean liquid will be used for normal flushing with the capability of switchover to the pumped liquid if the external source of clean liquid is interrupted. 

Bearing and lubrication system

Pump bearings and their lubrication have usually been the source of problems. A sophisticated lubrication system should be provided. Bushings in vertical pumps are usually lubricated by the liquid pumped. Alternative methods of lubrication should be used if the pumped liquid is not suitable for this application.

Bearing details, such as type, sizing and life calculation, and lubrication system details should be reviewed carefully to ensure the reliability and long, trouble-free operation of vertical pumps. Rolling bearings are still widely used in vertical pumps and vertical motors, as it is common to see vertical motors as large as 600 kilowatts (kW), or even larger, equipped with spherical or taper roller bearings. Therefore, bearing life expectation and calculation are usually topics for discussion and challenges. Any bearing life expectation less than four years (say 32,000 hours) at worst conditions is often discouraged; although, unfortunately, many manufacturers still use traditional life values of 16,000 hours or 20,000 hours for the bearing sizing and selection. 

Case study: Large vertical seawater pump installation

In a series of identical vertical seawater pumps at a large processing plant, pumps are vertically suspended (type VS1). The pump capacity and discharge pressure is 8,300 m3/h and 4.4 Barg, respectively. Three pumps operate in parallel to provide the seawater requirement for the plant. The rated hydraulic power of each pump is around 1 megawatt (MW); the rated electric motor power is about 1.4 MW. The electric motor is sized for the end of curve; therefore, suitable margins and factors on power rating are provided. 

The BEP flow of the pump is around 8,750 m3/h; the rated point flow is about 95 percent of the BEP flow. The pump efficiency at rated point is estimated around 85 percent, which is relatively high for a vertical pump. The head rise to shutoff is estimated at around 26 percent, which is assessed as suitable for this service.

The pump speed is 750 rpm, and a direct-drive vertical electric motor is used (no gear unit). The pump is wet-pit, a vertically suspended, single-casing diffuser pump with discharge through the column. The discharge nozzle of each pump is 40-inch ASME B16.5 150# flange. The overall vertical pump train is more than 14 meters (m) long. The column section is furnished in parts not exceeding nominal length of 3.2 m to ease transportation and installation. Sections are connected by flanges, and each pump train weight is more than 27 tons (T). 

The seawater was considered dirty and polluted for this location; therefore, all materials of construction in contact with seawater are considered super-duplex stainless steel. Line shaft bearings, thrust bearings and mechanical seal are provided with dual-flush system (utility water and seawater); the automatic switchover capability from utility water flushing to seawater flushing and vice versa are provided. In normal operation, clean utility water is used for flushing, and it can switch over to seawater automatically if the clean utility water is interrupted. In addition, an operator can switch over from one to another. 

The pump package is provided with two accelerometers (X-Y) for the electric motor radial bearings (NDE and DE), three accelerometers (X-Y-Z) for pump thrust bearing, one key phaser, and one duplex RTD per bearing for an effective vibration condition monitoring. 

A sophisticated seawater intake package is provided for each pump to filter the seawater and protect each pump. The seawater intake system is a self-cleaning, vertical traveling type. This is a complex and multistage seawater filtration package including Bar screen — 50-millimeter (mm) filtration level —, band-screen system and screen wash system to wash accumulated trash and solids. The screen washing is accomplished by using filtered and treated seawater.  

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