Screw pumps for viscous liquids principle of operation. Scope of application and operation features of screw pumps

screw pump- the pressure of the injected liquid is created by pushing the liquid out of the helical metal rotors that rotate inside the unit.

There are three types of pumps: single screw, twin screw, three screw.

Single screw pumps are a horizontal positive displacement pump, complete with a rubber static casing. This clip has a single-start screw and a double-start screw surface. The screw rotates in a cage that is made from metal. When it rotates, some cavities are created between the surface of the holder and the screw, into which the liquid is sucked in, which is pumped, after which the movement occurs along the axis of the screw to the injection cavity.
Twin screw pumps - the pump is also of a positive displacement type, in which there is an automatic priming function. These pumps are longitudinally balanced, and all of its components work without touching and without contact.
Three screw pumps are a positive displacement unit that consists of both a horizontal and a vertical three screw pump. Its electric motor is assembled on a platform and has a coupling connection.

Features of screw pumps

A feature of screw pumps is the design itself - it is valveless. The number of revolutions does not affect performance. The rotor-stator combination is the main part of the operation of this pump. A metal rotor is located in the nutria of the stator, as a result of the rotation of the rotor, the volume of the cavities changes, after which any liquid is pumped along the axis of the unit and displaced. The most main feature these devices in a pressure that does not depend on its pumping speed.

Pros and cons of screw pumps

Ability to self-prime liquid.
Excellent balance of mechanisms.
Low noise operation, minimum vibration.
Self-priming liquid.
Uniformity of liquid supply.
Simple and easy to maintain and repair.
Minimum wear.
Able to work even if there are solid inclusions in the liquid.
Low possibility of breakage of working parts.

For the manufacture of equipment, the high cost of work.
There is no possibility of regulation of the working volume.
There is no idle start - (there will be excessive heating).
Increased friction.
Poor cooling function.

The screw pump ensures uniform pumping of liquids. This type of device differs from others in low power consumption and high efficiency.

Due to its resistance to different kind environments, screw pumps are used in different areas industries, including various chemical industries.

1 Purpose and design features

The screw machine is used in various industries industry. Apparatuses of this type pump over viscous, dirty and gassed media.

Devices are used in the following industries:

pharmacology and cosmetic production;
food industry;
construction sites;
chemical industry;
extraction and processing of oil products;
Agriculture;
municipal and housing and communal works.

The units easily cope with anti-corrosion agents, silicone, latex liquids, paints, fats, milk, sour cream, yoghurts, creams, oils, shampoos, liquid soaps, groundwater, sandy water, ethylene glycols, polymers and other chemical liquids of different densities.

The device has the ability to operate in media of various viscosities due to the valveless design and the ability to change the flow direction.

Unit design:

body in the form of a cylinder or cone;
static stator;
movable metal rotor in the form of a screw;
rotor shaft;
connecting pin;
inlet pipe;
discharge pipe;
clutch;
bed;
working chamber.

1.1

Screw pumps are self-priming units.

In the mechanism, the pressure of the substance is carried out by displacing the pumped medium with the help of a rotor located and rotating in the stator.

The rotor draws water from the suction pipe while rotating in the stator. The substance moves in a spiral and enters the outlet pipe. Due to the fact that the protrusions of the screws enter into the depressions of the adjacent screw, a closed space is created. The pumped substance cannot be returned back.

1.2 The principle of operation of the screw pump (video)

1.3 Classification of mechanisms

Screw assembly - first of all submersible pump. According to the depth of immersion, they are divided into:

the deep view is operated at a depth of up to one hundred meters. The design difference of the device is in an elongated screw;
the standard view is operated in wells and wells up to twenty-five meters deep with sand inclusions.

According to the number of screws, the devices are divided into the following types:

single screw pumps are positive displacement mechanism horizontal arrangement. The device consists of a rubber holder with a two-phase helical surface. The metal screw rotates inside the cage. In the process of rotation, cavities are formed in the cavity between the cage and the screw. The working substance enters the cavity, after which it is transported to the discharge pipe. The single-screw pump transports mixtures with gas inclusions without jerks. The single screw pump is designed for viscous liquids without heating. Differs in simplicity of replacement of working knots;
twin screw pumps are used to transport water with a mixture of viscous substances such as oil. They are distinguished by a uniform supply of the substance without drops, a suction height of up to eight meters, the ability to transport the working fluid with varying degrees viscosity. Advantages - no noise, low wear of the mechanism, continuous transportation of liquids independent of pressure indicators;
three screw pumps are designed for transportation liquid substances without abrasive.

By appointment:

the OVN series is used for pumping viscous substances for chemical and food production;
the VNP series pump over liquids of average viscosity. These are devices for transportation of mayonnaise, varnishes and paints;
the OHVP series is used for transporting low viscosity liquids from a barrel;
ONV-food screw pump for pumping pasty products (sour cream, starch, dough, cottage cheese).

1.4 Advantages and disadvantages of screw pumps

Compared to other types of units, screw units have the following advantages:

ease of maintenance;
simplicity of design;
compactness;
low noise level;
uniformity of transportation;
high self-priming function;
pumping substances with solid particles;
low percentage of parts wear;
ease of dismantling;
reliability at low cost;
placement in any position.

Compared to work centrifugal pump, lasts longer in conditions of pumping water with sandy inclusions.

The devices also have disadvantages:

lack of volume adjustment;
dimensions weight more than other types of pumps.

1.5 Differences between screw and screw devices

Often two types of pumps are confused with each other due to the fact that both types of devices are displacing. By the nature of the operation, the devices differ from each other.

The screw electric pump is distinguished by the ability to work with inhomogeneous substances with inclusions of other substances. These devices do not break the pumped substance. The devices are operated under loads different kind at constant pressure. The pumped liquid is not working.

2 Mounting

The screw type water pump is installed in the following order:

assembly according to the instructions;
cable connection;
water hose connection;
fixation of hoses with clamps along the entire length;
installation of a cable for insurance of the unit;
float installation (if included);
immersion in the well;
fixing the device;
testing.

If there is no knocking and vibration during operation, then the installation was done correctly.

Units should not be installed above the engine due to the ingress of liquid into the engine

2.1 Operating rules

To prevent breakdowns, observe the following rules:

when pumping liquids of high viscosity, devices with revolutions of three hundred rpm are used;
when transporting viscous substances, stuffing box seals are used, which must be tightened over time;
when calculating the resistance for pumping viscous substances, height differences, length and material of the line are taken into account;
the device is used under the bay to prevent dry running;
solid inclusions are washed out of the chamber before launch;
when operating in conditions of fibrous inclusions in liquids, crushers are mounted before entering the device. This procedure prevents fibers from wrapping around the rotor and protects against wear.

2.2 Which device to choose?

Before purchasing, each buyer thinks about which unit to choose. There are not many selection criteria. Device must be selected conforming to the conditions operation:

Before purchasing, you need to determine the power of the device. The device should be chosen a little more power than necessary. This will ensure a stable fluid pressure;
manufacturing material. The material of a quality pump is stainless steel. Units made of other materials will be unreliable and will quickly fail;
manufacturer's name. When choosing a pump, you need to pay attention to a reputable manufacturer on the positive side. The manufacturer, distinguished by the manufacture of quality goods, provides customers with high-quality devices that serve for a long time.

After choosing and purchasing a unit, it is worth purchasing a repair kit for a screw pump. The repair kit is necessary for quick replacement of the working screw in case of its breakage.

Screw units are simple in design, reliable and durable.

screw pump

The internal structure of a three-screw pump

screw or screw pump - pump, in which the creation of the pressure of the injected liquid is carried out by displacing the liquid with one or more helical metal rotors rotating inside the stator of the appropriate shape.

Screw pumps are a type of rotary gear pumps and are easily obtained from gear pumps by reducing the number of gear teeth and increasing the angle of inclination of the teeth.

Design of screws in a twin-screw pump. Fluid moves along the axis of the pump

Principle of operation

Liquid is pumped by moving it along the axis of the screw in the chamber formed by the helical grooves and the surface of the body. The screws, entering the grooves of the adjacent screw with their helical protrusions, create a closed space, preventing the liquid from moving back.

Application area

Designed for pumping liquids of varying degrees of viscosity, gas or steam, including their mixtures.

These pumps can operate at pressures up to 30 MPa.

First introduced into practice in 1936, screw pumps have a simple design, can operate in the presence of mechanical impurities and with viscous fluids, which is necessary when solving various practical problems. Big number Screw pump units (PPUs) are used to remove water from wells producing coal bed methane, primarily due to their ability to pump liquids with mechanical impurities. However, screw pumps are also suitable for other gas wells, as well as for water and oil production.

Design features

To improve the quality of seals and reduce leakage, a cylindrical or conical flexible body is sometimes used. In the latter case, the conical screw is pressed by a spring, and sometimes also by the pressure of the pumped liquid. However, flexible casing pumps are able to withstand lower pressures than metal casing pumps. In pumps with conical screws, a rigid casing can be dispensed with.

The most common are three screw pumps.

Advantages

uniform fluid supply, unlike piston and plunger pumps;
the ability to pump mixtures from liquid and solid phases without damaging solids in liquids;
like other volumetric pumps, screw pumps have the ability to self-prime liquid;
opportunity to get high pressure at the outlet without multiple injection stages;
good balance of the mechanism and, as a result, low noise level during operation.

disadvantages

the complexity and high cost of manufacturing the pump;
unregulated working volume;
just like other types of positive displacement pumps, screw pumps cannot be idle without a pumped liquid, since in this case the coefficient of friction of the pump parts increases and cooling conditions worsen; as a result, the pump may overheat and fail.

Literature

1. Skhirtladze A.G., Ivanov V.I., Kareev V.N. Hydraulic and pneumatic systems. - Edition 2, supplemented. M.: ITs MSTU "Stankin", "Janus-K", 2003 - 544 p.

2. Lee James, Nickens Henry, Wells Michael. Exploitation of flooded gas wells. Technological solutions for removing fluid from wells / Translation from English. - M.: LLC "Premium Engineering", 2008. - 384 p., ill. (Industrial engineering).

Notes

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See what the "Screw Pump" is in other dictionaries:

Rotary pump with working bodies in the form of one leading and usually two driven screws that are in engagement. When the screws rotate, the liquid cut off in the cavities of the screw thread moves along the screws and is pushed out into the pressure pipe ... Big Encyclopedic Dictionary

screw pump- Rotary rotary pump with movement of the liquid medium along the axis of rotation of the working bodies. [GOST 17398 72] Inadmissible, not recommended screw pump Subjects pump EN screw pump DE Schraubenspindelpumpe FR Pompe a vis … Technical Translator's Handbook

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Rotary rotary pump movement of working bodies (screws). In the case of V. n. there are one driving and one, two or four driven (sealing) screws. The gap between the screw threads and the case is small. Screw engagement line within one pitch… … Big encyclopedic polytechnic dictionary

A hydraulic machine, the working body of which is a screw: serves to supply fluid, including with increased viscosity. V. n. is a kind of rotary pumps, also called worm pumps. In the case of V. n. there is ... ... Great Soviet Encyclopedia

Pump, screw- Screw pump Ndp. Worm pump Rotary rotary pump with movement of the liquid medium along the axis of rotation of the working bodies See all terms GOST 17398 72. PUMPS. TERMS AND DEFINITIONS

A screw pump, or as it is also called, a screw pump, is one of the varieties of rotary gear pumps. The pressure of the pumped liquid in it is created due to its displacement by one or more helical metal rotors rotating inside the stator.

A screw pump can be easily obtained from gear pumps by increasing the angle of inclination of the teeth in them and reducing the number of gear teeth.

The principle of operation of the screw pump

Due to the movement of liquid between the surface of the body and the helical grooves along the axis of the screw, it is pumped. The screws enter with their protrusions into the grooves of the adjacent screw and thereby prevent the liquid from moving back.

Scope of screw pump

It is used for pumping steam, gas, their mixtures and liquids of varying degrees of viscosity.

For the first time, screw pumps were introduced into production in 1936. Them simple design allows you to work, including in the presence of mechanical impurities with viscous fluids at pressures up to 30 MPa. Such characteristics are important in solving various practical problems.

Installations of screw pumps in large quantities are used in wells for the extraction of methane from coal seams to pump out water from there. They are also suitable for water, oil and other gas well applications.

Design features of screw pumps

In order to improve the quality of seals and reduce the number of leaks in screw pumps, conical or cylindrical elastic casings are used. The conical screw is securely pressed by a spring and pressure from the pumped liquid, which significantly reduces leakage. However, pumps with a flexible case can withstand much less pressure than their counterparts with metal cases. A rigid housing is also suitable for a pump with a conical screw.

The most common type of screw pumps are three-screw pumps.

In practice, they have found the widest application.

Their characteristic benefits include:

uniform supply of liquid (gas, steam);
the ability to pump liquids with solids without damaging them;
ability to self-soak up liquids;
without many injection stages, it is possible to obtain high outlet pressure;
low noise level during operation;
good balance of mechanism.

The disadvantages of this type are:

high cost and complexity of manufacturing the pump;
inability to adjust the working volume;
inadmissibility of use idle (without pumped liquid).

The principle of operation that screw pumps have

Modern screw pumps, according to the principle of operation, are positive displacement rotary hydraulic machines. The working bodies are a screw pair with internal gearing. The movable element of the working pair, the screw (rotor), makes planetary motion in the holder (stator).

The clip has an internal helical surface with a pitch twice the pitch of the screw. Being in constant contact, the holder and the screw form several closed cavities along the length of the screw - holder. When the screw is rotated, the cavity on the suction side increases in volume and a vacuum is created in it, under the action of which the cavity is filled with the transported medium. Further rotation of the screw moves the cut-off volumes of the transported medium towards the discharge side.

At a set screw speed, the speed of the transported medium and the productivity that screw pumps have during operation are constant, because invariably the flow area of the screw and clip.

Screw (screw) pumps are positive displacement pumps, the design of which allows you to create a stable pressure and allow adjustment of performance without loss of nominal pressure. Screw pumps have a long service life, high efficiency, are reliable and versatile when working with a wide range of tasks.

A screw screw pump is a device in which the pressure of the impelling material is created by the displacement of the pumped liquid by one or more helical metal rotors that rotate inside a stator made of an appropriately shaped elastomer.

The production of screw (screw) pumps requires precise manufacturing of parts, such as a working pair - a rotor and a stator, in the development and manufacture of which special high-precision equipment is used. Computer calculation using special programs - guarantee High Quality, which increases the life of the equipment and reduces energy consumption during pump operation.

Screw pumps are used to work with thick, viscous and viscous masses, as well as for pumping low-viscosity products. Depending on the design of the pump and its material design, it is possible to pump resins, pastes, oils, food products, abrasive or even corrosive liquids so that the particles included in their composition are not crushed or destroyed by mixing with the base liquid.

Screw pumps are designed to work in food production, mining or chemical industry, recycling Wastewater in the municipal and industrial sector, petrochemical industries, pumping sludge deposits, for work in gas and oil production, shipbuilding, wherever reliable and simple equipment is required for permanent job, unpretentious in operation and subject to simple maintenance and repair. Applications for of this type pumps are almost endless, thanks to their special design, the materials used, technical features and special operating mechanisms.

Advantages of screw pumps

The most uniform liquid supply among all positive displacement pumps. No pulsation;
Pumping liquids containing solids, impurities and abrasives, multiphase media with great content gas;
Pumping products with low and high viscosity (1 mPa*s to 5 million mPa*s);
Pumping aggressive (pH from 1 to 14) and toxic media;
Screw pumps are self-priming;
The pressure does not depend on the speed of the pump (capacity control);
Silent operation;
Ease of maintenance.

Screw pump - a pump in which the pressure of the pumped liquid is achieved by displacing the liquid with screw rotors (one or more) that rotate inside the stator of the appropriate shape. By the nature of the impact of the working bodies, screw pumps are volumetric.

Screw pumps are rotary gear pumps and can be made from gear pumps by reducing the number and increasing the angle of the gear teeth.

Types of screw pumps. Single screw, double screw, triple screw.

Single screw pumps– are horizontal positive displacement pumps. The main components of such pumps are a static rubber casing, which has a two-start helical surface and a single-start screw made of metal, which rotates in the casing. During rotation, cavities are created between the screw and the surface of the cage, where the pumped liquid is first sucked in, and then moves along the axis of the screw to the discharge cavity.

Twin screw pumps- are used mainly when pumping sea, fresh and mineral water with an admixture of oil products.

Twin screw oil pumps– are used mainly when pumping fuel oil and other viscous liquids. This type of pumps has a single mechanical seal, a heating jacket, the solid part is made of structural steel.

Three screw pumps– are used mainly when pumping non-aggressive liquids that have lubricity and do not contain abrasive mechanical impurities. The minimum viscosity is limited by the lubricity of the liquid, the maximum by the power of the electric motor and the suction capacity of the pump.

Differences between screw and screw pumps

In one group with screw pumps, screw pumps are often combined, due to the fact that both types of pumps are displacement pumps. However, according to the nature of the impact of the working bodies, screw pumps are dynamic.

The main component of the screw pump is a gerotor (screw) pair, which determines the properties of the pump unit, and also determines the mechanism of its operation. The screw pair consists of a static element - the stator and a moving part - the rotor. The stator is an internal spiral with the number of turns "m+1". This element made of elastomer and integrated with an iron clip. The rotor is an outer spiral with the number of starts "m". This item is made of steel further coating or without it. The most common classical model are pumps with a two-way stator and a single-thread rotor.

The principle of operation of the screw pump

Screw eccentric screw pumps have many qualities that make them indispensable when working with inhomogeneous viscous substances, substances with various impurities, as well as in those areas where it is simply impossible to use other pumping units due to different substrates. These pumps are self-priming and do not require “filling”, in other words, the pumped substance is not a working medium.

Screw eccentric pumps can pump inhomogeneous substances with various impurities. The size of admissible inclusions depends on the size of the closed cavities between a rotor and a stator. One rotation of the rotor corresponds to a certain size of the pumped substance, which allows fine tuning unit. Pumps of this type do not experience pulsations or flow breaks, despite the fact that they are able to withstand any production load at a stable pressure.

Main knots

The design of screw pumps includes such elements as: a drive motor-reducer, an adapter stand, a stator-rotor pair, an outlet pressure pipe, a chamber, a hinge, a shaft sealing device.

The main working part of a screw pumping unit is a screw pair. Inside the stator, made of elastomer, there is a helical metal rotor. The rotational movements of the robot lead to a change in the volume of the cavities inside the pair and the pumped liquid moves along the axis of the pump. The liquid is displaced, and the change in volume in the cavities creates a suction effect.

The principle of operation of the screw pump

The screw pump consists of a rotor (single moving part, number of strokes "m") and a stator (internal spiral, number of strokes "m+1"). The liquid is pumped by moving along the axis of the screw, not being able to move back due to the closed space that the screws create when the screw protrusions enter the grooves of the adjacent screw.

Temperature

The type of pump stator determines the maximum operating temperature of the liquid.

In addition, the temperature may be determined by the nature of the liquid and the operating conditions of the pumping unit.

Liquid intake parameters

The screw pumping unit is self-priming, even with small delivery volumes, and when working with water with temperatures such as 20 ° C, specific gravity 1 and viscosity level 1 °, the head it creates is 7 m of water column.

Feed characteristics

Progressive screw pumps operate on a positive displacement positive displacement principle, which results in a constant, smooth and fluctuating material flow.

Acceptable fluids

Screw pumps have elevated level chemical and mechanical resistance due to the fact that the stator is made of elastomeric material. These pumps are used for pumping any liquids with abnormal (non-Newtonian) viscosity. In addition, screw pumps are able to pump liquids containing solids (except abrasive) without sacrificing performance levels.

Commissioning and adjustment

In order to protect the pump stator, it is necessary to fill the pump with pumping liquid. After that, it is necessary to check that the shut-off valves of the inlet and outlet pipes of the pump are open. If the pump has a motor permanent action with adjustable speed, to regulate the flow rate of the medium, directly on the pump must be installed desired speed supply or install a control valve between its inlet and outlet.

Security measures

When turning on the pump, a number of safety precautions must be observed. Turning on the pump without filling the medium can lead to deformation of the stator, therefore it is forbidden to turn on the pump without liquid!

You should also avoid adjusting the pump flow rate by closing the supply valve, as this leads to deformation of the drive mechanism and the motor, in case they do not have an overload protection relay.

Key parameters to consider when choosing a pump

In order to select the most suitable pump for your production, a number of key parameters must be considered. First of all, it is necessary to determine the type of installation of the pump and how the pump will be used in the system. In addition, it is important to take into account the flow rate of the pumped liquid (l/min or m³ / h.), The total pressure of the delivery head (bar), as well as the height of the liquid column under the suction nozzle of the pump (NPSN). The list of key parameters to consider when choosing a pump also includes the nature of the pumped substance (chemical composition, density, viscosity, pH, temperature), as well as the level of suspended solids in it and the degree of abrasiveness. In addition, you should consider the level of supply voltage and frequency of the network for connecting the motor, as well as the type of transmission mechanism between the motor and the pump.

Design features

Durability. The screw is driven by an electric motor and does not come into contact with inner surface pump housing. This reduces friction to a minimum, which ensures a long service life.
The medium moves in the pump with a constant axial flow direction. Due to this, the pump will deliver the product at the outlet in a smooth flow, without pulsations. The pump has low noise pollution rates. Also, since the moving parts of the pump have low energy, the starting torque and vibration will be low.
The pump has a high suction capacity.
In order to ensure the safe operation of the pump, engine, piping system, all high-power pumps are equipped with safety valves. If the operating pressure exceeds maximum pressure, for which the system is designed (for example, the injection pipeline), is triggered safety valve and excess product will be directed through the bypass back to the suction chamber.

Advantages of screw pump

Screw pumps have a number of advantages over pumping units of other types. So, unlike centrifugal pumps, screw pumps pump liquid in an even, non-pulsating flow, which allows you not to mix the liquid and preserve its structures.

Unlike impeller pumps, self-priming screw pumps work better with thicker substances, and they also have outlet pressures up to 4-24 bar.

Compared to piston and plunger pumps, the advantage of screw pumps lies in the uniform supply of liquid, as well as the ability to pump mixtures of liquid and solid phases without damaging solids.

Among a number of advantages of screw pumps, it should be noted high ability of these installations to self-priming, as well as the simplicity of the design, which makes maintenance of the pump convenient. The pump consists of three main parts: a stainless screw, a rubber cage and a shaft seal. The liquid supply in the screw pump is proportional to the rotation speed, which provides an easy adjustment of the pump parameters in the presence of a frequency drive. The self-adjusting clearance cage design provides high pump pressure in a small package. With increasing pressure, the gap between the working surface of the screw and the cage remains constant.

Like other types of volumetric pumps, screw pumps have the ability to self-prime liquid from a depth of up to 10 meters. In addition, screw pumping units have an optimally balanced mechanism and, as a result, a low noise level. These types of pumps are unpretentious in operation.

Application in industry

The first models of screw pumps appeared in the 1920s and after 10 years were used in production. The maximum operating pressure of pumps of this type can be up to 30-35 MPa.

Screw pumps are used for pumping liquids of various viscosities, gas, steam, and their mixtures. As a result, screw pumps have been widely used in the fields of waste processing, tobacco production, textile and paper industry, metal processing, food and chemical industries.

Since the 1980s, screw pumps have been actively used in oil production and are still one of the most promising technologies in this industry.

Screw pumps are used for pumping oil products without mechanical impurities: fuel oil, oil, oil, diesel fuel, paraffin and other lubricating liquids.

Especially for the food, chemical and pharmaceutical industries, sanitary single screw eccentric pumps have been developed. These products have a classic configuration with articulated sealed units, which ensures the strength of the unit, as well as ease of operation and maintenance.

Screw pumps for viscous liquids principle of operation. Scope of application and operation features of screw pumps

Features of screw pumps

Pros and cons of screw pumps

1 Purpose and design features

1.1