Multistage pumps. Multistage centrifugal pumps: principle of operation, types, advantages and disadvantages Multistage pump

Practical reverse osmosis filters give the owner the opportunity to significantly improve the characteristics and taste of water, regardless of the location of the home and natural conditions terrain. Thanks to a well-thought-out design, including a complex of several cartridges with different fillers, they effectively rid the liquid of mechanical impurities such as clay, peat fibers or grains of sand, eliminate salt deposits of heavy metals, chloride compounds and bacteria, organic substances and foreign odors.

For proper operation of the system, the pressure in the water supply should not fall below 3 atmospheres. This value does not always reach desired value- for example, in country houses or on the upper floors it may be slightly lower. In this case, together with the filters, you will need to install a pump capable of increasing the pressure.

Operating principle

The device operates from the electrical network, connecting to it using an adapter, which can be supplied in the kit or purchased separately. To operate, the device also requires sensors that indicate the pressure level in the system. When its value drops below the required value, the pump turns on and runs until the storage tank is filled with filtered water.

Thus, this easy-to-use device allows you to provide and maintain pressure at the proper level, guaranteeing uninterrupted operation of the filtration system and always high quality drinking water in the house.

Advantages

The advantages of pumps for reverse osmosis systems include:

• the ability to increase pressure to a level of about 8 atmospheres;
• ease of installation and use;
• economical energy consumption;
• low noise level during operation;
• compact dimensions;
• universal design, allowing the use of one pump for filters from different manufacturers.

Centrifugal multistage pumps are fairly common types of dynamic hydraulic machines. They are quite widely used in water supply and wastewater systems, in the chemical and nuclear industries, in thermal power engineering, in aviation and rocket technology.
This article describes what features of the devices, their advantages, and how to install the units yourself.

Types of centrifugal pumps

Units can be classified according to the following distinctive features:

• By number of steps:

1. single-stage units;
2. two-stage;
3. multi-stage.

• What is the number of fluid flows:

1. single-threaded;
2. with two streams;
3. multi-threaded.

• By what principle is liquid supplied to the impeller?

1. with spiral outlet;
2. along an annular outlet, with a guide vane;

• What design impeller:

1. closed ;
2. open impeller.

• How the drive is made:

1. using a coupling;
2. through the gearbox.

• By shaft location:

1. vertical;
2. horizontal.

• Pump with wet rotor. In this case, the engine rotor moves directly the fluid. The engine stator, which is constantly under voltage, is separated from the rotor by a special sleeve, 0.1 to 0.3 millimeters thick, made of stainless steel.
  The rotor bearings are lubricated by a liquid medium, which also performs the function of cooling the rotor. The pump shaft is mainly located horizontally.
• Dry rotor pump. Here the motor rotor does not come into contact with the liquid medium that is being pumped. They usually have a large fluid supply.

Advantages and disadvantages of centrifugal pumps

Compared to other types, centrifugal pumps have advantages:

• In a wide range of flows Q, fairly high values ​​of efficiency and pressure H are maintained, as a result of flat characteristics H = f(Q) and η = η (Q.
• Increased rotation speed, which allows the pumps to use electric motors and turbines as drives.
• The change in power N has a smooth shape, which allows the pump to be started with the outlet valve closed or the check valve closed.
• They have good stability in the operation of the devices and expansion of the technical values ​​of H and Q with parallel and series connection of pumps, when working on one pipeline.
• Transient processes occur smoothly when operating modes of hydraulic systems change.
• The pumps are located above the liquid level in the flow tank.
• Due to various factors, the performance of pumps H, Q, η changes. These factors are:

1. turning the diameters of impellers;
2. change in rotation speed;
3. change in frequency of power supply.

• Low price of the pump, which is associated with the use of relatively inexpensive structural materials in the product:

1. become;
2. cast iron;
3. polymer materials.

• Easy to maintain and operate.
• High reliability during operation.
• Large fluid supply Q.
• Liquid flows with small, uniform pressure pulsations.
• They work successfully on “contaminated” liquids.

The disadvantages of centrifugal pumps are:

• The unit must be primed before starting it up.
• They have a tendency to cavitation.
• Reduced efficiency when pumping viscous liquids.
• Low efficiency value with small liquid supply Q.
• It is better to use in the area of ​​large water supplies Q and low and medium pressures N.

Advice: You cannot use such devices without first filling them with water.

Operating principle of multistage centrifugal pumps

The instructions for multistage pumps indicate that they are used for pumping hot and cold water.
In this case, they can be used to ensure:

• Heat and water supply.
• Increased pressure.
• Fire fighting.
• For feeding steam boilers.
• Used in industrial circulation, washing, irrigation, air conditioning and watering systems.

A multistage centrifugal pump operates by rotating several wheels at once. In this case, the liquid that sequentially passes through the wheels moves quickly through the pipe.
In this case, the pressure of the water supplied to the water supply system directly depends on the sum of the pressures of the elements arranged in succession and delivering the same supply. Each stage adds flow pressure, which depends on the power of the wheel, and the total pressure of the pump will be equal to the sum of the pressures of all its stages.
Based on the location of the piston, pumps are divided into two types:

• Horizontal. This device is an excellent option for increasing the pressure for water supply in an apartment or private house.
  Such a unit will successfully cope with the organization of autonomous water supply. More often horizontal pumps are manufactured surface-mounted, their design does not imply immersion in the pumped medium. Devices are also used to solve more specific problems:

1. they are installed to install an irrigation system for the site;
2. to speed up the filling of the pool.

• Vertical(see). When the well is located near the house the best option To provide water to the house, a multi-stage vertical pump will be installed.
  With its help, you can pump out water from a depth of up to 20 meters, which is enough to satisfy the requirements of almost all customers.

Design of centrifugal pumps

Main elements of the unit:

Here are the positions:

• 1 – element for fixing the drive shaft.
• 2 – clutch.
• 3 – main shaft.
• 4 – sealing element.
• 5 – rotor.
• 6 – rings.
• 7 – inner bushing.
• 8 – head.
• 9 – bowl.
• 10 – internal body.
• 11 – lower liner.
• 12 – column.

Below are the main components of the device.

The main components that make up a multistage centrifugal pump are:

• Frame. Ensures tightness of the product connector, rigid fixation against any displacement of all its elements, and at the same time guarantees the required working gap in the flow part.
  Fixed compression control ensures the use of a special metal-to-metal gasket in the radial connector. Any movement that may be caused by thermal expansion is guaranteed by the housing support located along the centerline of the pump. High-grade steel is used for its manufacture.
• Rotor assembled. It represents the basis of the unit. Greater reliability and performance are ensured by the accumulation of high technologies.
  Its design ensures that the device operates with specific liquids at maximum performance. These are single-suction and closed-type impellers rigidly mounted on the shaft. Rotors and impellers are dynamically balanced.
• Balancing disc. Serves to reduce the load to the optimal value, which increases the service life of the bearings.
  The element is located behind the last impeller. At the same time, it reduces the thrust force on the rotor shaft, which is caused by the impellers, which reduces the load on the bearings.
• Main shaft. Provides minimal shaft movement to maximize bearing and seal life.
• Shaft seals. Seals of any type complying with API 610 standards are mounted in a horizontal plane.
• Deflectors and end seals. They serve to ensure a guaranteed volume of oil in the bearing assembly and protect the assembly from foreign mechanical impurities.
• Impellers or impellers. Newest computer programs, using hydrodynamics, made it possible to design wheels with optimal performance and improved dynamic characteristics.
  To minimize shaft vibrations and balance its rotation, the impellers are fixed to the shaft by a press fit using split rings and double-action keys.

In addition to the mentioned designs, multistage centrifugal pumps are used, which are connected to the engine through a multiplier.
For use in harsh operating conditions such as those found in fertilizer production or other processes where high pressure, gas processing industry, a multi-stage centrifugal pump is used. Its diagram, with the engine connected through a multiplier, is shown in the photo:

Tip: When choosing a pump of any type, you need to be guided by its parameters. Qualified specialists will help you choose the right product.

The operation of multistage centrifugal pumps can be seen in detail in the video in this article.

Cantilever centrifugal pump: spiral outlet pump housing; Working wheel; housing support; front cover with suction pipe; - shaft; screw; ball bearing;

gland packing; - oil seal bushing.

All existing centrifugal pumps can be divided into the following groups: 1) according to the method of water removal: a) simple (without a guide vane);

b) turbine (with a guide vane); 2) by the number of impellers: a) single-stage; b) multi-stage; 3) for water supply: a) with one-way supply; b) two-way supply;

4) according to the position of the shaft: a) with a horizontal shaft; b) with a vertical shaft; Multistage pumps are designed to create high pressures. Several impellers are rigidly fixed on a common shaft rotating from the engine, through which the flow moves sequentially. To direct the flow from the output of the previous to the next impeller, a guide vane is used in sectional pumps; it consists of 2 systems of blades, guides (located behind the impeller and return .In other pump designs for this purpose, there are special channels or additional pipes in the housings, which impairs compactness. When the flow moves sequentially through the impellers, the pressure increases, at the outlet of the pump it is determined by the product of the pressure of one stage by the number of feet. There are horizontal and vertical .Horizontal 3 types of central nervous system

Depending on the method of supplying fluid to the impellers:single-threaded;multi-threaded.

According to the method of draining fluid from the impeller: spiral (volute); turbine type.

According to the body design: single-body type; sectional type.

By number of impellers: single-stage; multi-stage.

By degree of speed: low, medium, high speed.

According to the drive method, pumps are divided into: electric drive, steam (the drive is driven by the extraction of steam from the steam turbine).

According to the location of the shaft axis: horizontal, vertical,

By type of application: mine, sewer, nutrient;

By type of pumped liquid: acid, sludge, dredge, fecal, etc.

Centrifugal pumps are the most common type of pump among the wide range of pumping equipment presented in Ukraine. Thus, more than 50% of the pumping equipment market is accounted for by centrifugal pumps. The company "Vaterpass" offers centrifugal pumps from well-known foreign manufacturers: Salvatore Robuschi, Varisco, JEC.

The secret to the popularity of centrifugal pumps lies in their high performance, durability and wide possibilities applications. Pumps of this type are used in water supply and drainage, metallurgical, oil, chemical, food and other industries. Regarding the strength of centrifugal pumps, it should be noted that they are designed for constant pumping and their parts are practically not subject to wear - and this means that there is no need for frequent replacement of equipment parts, which allows you to avoid significant waste of both the financial resources of the enterprise and time on production downtime. In addition, the design features allow for simple and quick maintenance of the pump. Centrifugal pumps are also attractive for their ability to be used in conditions of increased hygiene requirements, ultra-high temperatures (up to + 350° C) and in conditions of interaction with chemically aggressive substances. One of the most significant aspects of the attractiveness of centrifugal pumps in the pumping equipment market is their high performance. The minimum pumping volume of centrifugal pumps is sometimes equal to the average performance of other types of pumping equipment, and their maximum productivity reaches about 2.5 thousand m 3 per hour.

Based on installation characteristics, centrifugal pumps are divided into monoblock and cantilever pumps.

Separation of pumps according to installation principle.

Single-stage centrifugal pumps are widely used in many fields of activity and are designed for pumping water, suspensions, emulsions, chemically active liquids, and are also installed in underground pumping stations.

Single stage RC pump.

Single stage RD pump.

Single stage RDL pump.

Single stage pump RS.

Multistage centrifugal pumps are distinguished by their ability to achieve high heads with relatively small flows. Multistage pumps are divided into sectional and spiral. A multistage centrifugal pump of a sectional type pumps liquid through the guide vanes of each section sequentially from one wheel to another. The flow rate of pumps of this type reaches 850 m 3 /h, developing a pressure of up to 1900 m.

Multistage scroll pumps have a number of advantages over sectional pumps. Thus, they are characterized by higher efficiency, ease of assembly and disassembly, balanced axial pressure, and the absence of guide vanes, which makes it possible to significantly grind the wheel without significantly reducing the efficiency of the device.

Multistage centrifugal pumps are used in heating systems, water supply and air conditioning systems, hot water supply, for irrigation and fire fighting, and can also be used for pumping aggressive media.

Multistage pump TS.

Selecting a particular pump requires determining a number of parameters and consulting a qualified specialist. The type of centrifugal pump that will meet all the client’s needs will be determined by a consultant from the Voterpass company.

Centrifugal pumps are called dynamic hydraulic machines. The functional task of such equipment is to pump liquid, which is carried out if the kinetic energy of rotation is converted into hydrodynamic energy of the flow. To rotate the pump shaft, an electric motor or internal combustion engine is provided. The liquid reaches the impeller, which has blades on the body necessary to act on the liquid particles and transfer energy to them.

Centrifugal forces act in such a way that the fluid is directed towards the periphery of the impeller. In this area, through a special annular channel, which is also called a cochlea, the liquid is supplied to the pressure pipe, that is, the diffuser. And the task of this element is to convert part of the dynamic energy into static energy.

A multistage centrifugal pump is more advanced equipment, the design of which involves several impellers and stages located one after another. When choosing a centrifugal pump, you should pay attention to how the shaft is sealed. Modern models They differ in the mechanical seal, whereas older models have a stuffing box. The first configuration is good because it maintains the tightness of the structure and prevents leaks. Even if the pump operates with vibrations or its shaft moves slightly, this will not cause a leak.

At the moment, there are a considerable number of pumps for pumping liquids, and the most common of them are centrifugal. They differ in their design features and are single- or multi-stage.

Multistage pump and its diagram

Centrifugal equipment is assembled from such elements as a pressure pipe, a guide vane, wheels and a spiral outlet.

When the wheels begin to rotate, the part that has special bends on the blades is filled with liquid.

It is necessary to understand that there are many models of such pumps, which differ from each other in the design of the assembly - how the shaft is located, what shape the pipes are and how many impellers are installed. When choosing, you should also take into account the power and dimensions of the equipment.

Design Features

Single-stage equipment is equipped with one impeller, while a multistage pump is supposed to have two or more. As for the principle of operation, it is identical; the number of wheels is directly related to the performance of the unit. Thus, multi-stage pumps are able to pump more water in a certain time, and also have increased pressure, that is, liquid can be pumped over long distances, compared to a single-stage pump.

Multistage centrifugal pumps also have different designs and can be sectional or spiral. As for the sectional one, it pumps liquid sequentially, that is, from one drum to another. The maximum performance level of the described equipment is 900 cubic meters water per hour with a pressure of 1900 meters.

Strengths and weaknesses of centrifugal units

This pump equipment, which uses centrifugal force, is now in considerable demand. The reason for this is various operational advantages, which we will highlight below:

• Since the rotation shaft is directly connected to the engine, the pumping equipment is compact and light in weight. The design itself does not provide for transmission mechanisms;
• a reliable and durable device that does not require regular maintenance;
• because working environment is supplied as smoothly as possible, this guarantees the absence of water hammer in the system;
• To operate the pump, contaminated liquid containing mechanical particles may be used. This is due to the fact that the design of the device does not imply the presence of valves;
• again, maximum simple design pump allows you to distribute it at an affordable cost;
• Easy to use, even a beginner can handle it.

Even an untrained user can understand the circuit of a multistage pump. These devices serve the purpose of pumping liquid, but can also work with other compounds, the main thing is that they are not chemically aggressive.

There are also negative sides, one of which is low efficiency if the low-performance mode is activated. This problem becomes critical if it is necessary to pump a small volume of water under high pressure.

In addition, it will not be possible to quickly put the pump into operation, since before you start pumping liquid, water must be introduced into the device body.

If you do not pay attention to these disadvantages, then if you need truly productive work, centrifugal pumps are considered the optimal equipment for fulfilling these purposes.

Types of multistage pumps

Based on the position of the equipment piston, the device can be:

• horizontal. Allows you to increase the water supply pressure, therefore it is popular for use in apartments and country houses. If it is needed autonomous water supply, such pumps also cope with the task successfully. Often such equipment involves superficial work, meaning they do not need to be immersed in liquid to function. Thus, a multi-stage centrifugal pump allows you to: speed up the filling of the pool or organize an irrigation system on the site;
• vertical. Such a well is best suited if there is a well on the site, located near the house. The pump effectively pumps water from a depth of about 20 meters, which is enough for many users.

Main components of a multistage pump

• frame. Its task is to ensure the tightness of the structure and its fixation;
• The rotor is the basis of the entire unit. Since they are accumulated high tech, this element is distinguished by reliability and performance. Design features allow the device to interact with various liquids;
• balancing disk. Allows you to reduce the load to the optimum, resulting in extended bearing life;
• main shaft Provides shaft stability in one place, which in turn increases service life seals and bearings;
• seals;
• deflectors. Provide a guaranteed volume of oil in the bearing assembly, and also protect it from mechanical particles;
• impellers and impellers. Minimize shaft vibrations and make its movements balanced.