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screw pump
Internal organization 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 housing. 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).
see also
- PCM screw pumps
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 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
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 ... encyclopedic Dictionary
screw pump- sraigtinis siurblys statusas T sritis automatika atitikmenys: engl. screw pump vok. Schraubenpumpe, f rus. screw pump, m pranc. pompe hélice, f … Automatikos terminų žodynas
screw pump- sraigtinis siurblys statusas T sritis Energetika apibrėžtis Rotacinis siurblys, turintis sukamojo judesio darbinius elementus. Sraigtinio siurblio korpuse yra vienas varantysis ir dar vienas, du arba keturi varomieji sraigtai. Didinant slėgį,… … Aiškinamasis šiluminės ir branduolinės technikos terminų žodynas
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
Screw pumps are widely used in the field of providing private houses and cottages with clean water from a well or well.
Every owner of his house knows that after purchasing a property, it is worth thinking about providing the house with water. After all, the lack of water supply can greatly spoil the impression of the purchase.
The right choice of a submersible pump, and in our case a screw pump, is a guarantee of uninterrupted water supply for a long time.
The screw pump for the well is well-deservedly popular among amateurs. country rest on their site, as well as among the owners of cottages and houses due to ease of operation and ease of installation. In addition, unlike a surface pump, a screw pump is distinguished by its versatility in supplying water from great depths.
The principle of operation of the screw pump.
The operation of screw pumps is based on the concept of the Archimedes screw.
Video of screw pump
Screw pumps are good for generating sufficiently high pressures with a small liquid supply. Screw pumps have become widespread recently, having found the greatest popularity in providing water from wells to private houses and cottages.
The most widely used screw pumps are chemical industry for pumping aggressive chemical media.
The screw or eccentric screw pump is a positive displacement pump that is widely used in the most various industries industry, used for example for pumping sugar syrup into Food Industry, and how submersible pump for wells, for development oil fields. A variety of applications is made possible by the design of the screw pump, which can provide a wide range of performance at sufficiently high pressures.
The screw pump is excellent for pumping highly viscous, shear sensitive products as well as liquids containing solids.
The main elements of a screw eccentric screw pump are a metal spiral rotor rotating in an elastomeric stator.
- Rotor
- stator
- suction pipe
- Discharge pipe
- Shaft seal
- Cardan joints
The principle of operation of the screw pump
The rotor fits snugly against the helical elastomeric stator, forming a double chain of sealed cavities. When the rotor rotates, the liquid is transferred in these cavities from the suction to the discharge pipe, without changing its volume and shape.
Material performance
A variety of materials are available for the main elements of the screw pump, providing the necessary resistance when working with aggressive, abrasive, high-temperature liquids
The following main materials can be distinguished:
Pump shaft seal types
- Stuffing box seal (link to stuffing box seal)
- Lip seal
- Mechanical seal (single or double) (link to mechanical seal)
- Magnetic clutch
Main versions of screw pumps
- Capacity: from 0.03 m3/h to 500 m3/h
- Maximum pressure (standard): 6 to 48 bar
- Number of steps (standard): from 1 to 8
Note: maximum pressure practically unlimited and depends on the number of pump stages installed in series. Almost all manufacturers produce pumps up to 8 stages, which corresponds to a pressure of 48 bar. Some manufacturers in the line have a high pressure screw pump up to 240 bar.
- Fluid viscosity: 1 to 3,000,000 cps
- Maximum solid inclusion size: 150mm
Advantages and disadvantages of screw pump
Advantages
- Pumping of highly viscous liquids
- High pressure
- Constant feed
- Possibility of self-priming
- Transfer of shear sensitive liquids
- Wide choice of materials
- Ability to work with liquids containing solids
- Wide feed range
Disadvantages:
- They take up too much space. The more stages the pump has, the longer the flow path becomes.
- Difficult to serve. To replace the main working elements, you need a lot of free space and special equipment.
- High cost of spare parts
- Rotor and stator are always in contact. Leads to increased wear when pumping abrasive liquids
- Dry running not allowed
Areas of use
Screw pumps are most often used in the following industries.
- Oil and gas industry
- Chemical industry
- Water treatment and water treatment
- Pulp and paper industry
- Paint industry
- food
- Pharmaceutical
- Shipbuilding and shipping
For the following tasks.
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 you to adjust the performance without losing the nominal pressure. Screw pumps have long term operation, high efficiency, 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- a guarantee of high quality, which increases the life of the equipment and reduces energy consumption during the operation of the pump.
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 that make up 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, processing Wastewater in the municipal and industrial sectors, petrochemical industries, pumping sludge deposits, for work in gas and oil production, shipbuilding, wherever reliable and simple equipment for continuous operation is required, 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 high gas content;
- 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 - 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.
