In systems autonomous water supply, as well as the functioning of systems for pumping various liquids various are used. For wells and wells in the private sector, I most often use submersible models, which include a screw pump for a well. This type of equipment is widely used not only in everyday life, but also in industry due to its simple and practically trouble-free design.
Screw pumps, also called worm pumps, operate using a simple mechanism based on a rotating screw (auger) located inside a cylindrical or conical body. The supply and movement of liquid inside the working chamber occurs due to the constant movement of the screw. During the continuous movement of the screw, the grooves on its surface force the liquid to move only forward, preventing it from flowing back. Thus, submersible screw pumps maintain a constant water pressure in the system without increasing operating pressure in the cell.
Rice. 1 Worm pump device
The peculiarities of the functioning of screw models of pumping equipment involves their immersion directly into the working environment - into a well or a well. This is due to the fact that such a design of equipment does not allow it to work on the so-called. Idling. For stable operation of the unit, a constant liquid level is needed, and without access to the working environment, the equipment simply stops.
Advantages and disadvantages of technology
Screw borehole pump(or centrifugal - as it is also called) is considered one of the preferred types of pumping equipment for supplying water to an autonomous water supply system, as well as in production for pumping and circulating various liquids - oil products, liquefied gas, aggressive working environments with a high content of chemical reagents.
The main advantages of submersible screw pumps are:
- high performance;
- ease of maintenance;
- lack of noise during operation;
- the ability to work with working environments of various quality.
The last point is one of the most important for many users of pumping equipment. While other models are quite sensitive to the composition of the working environment and can fail even with a small inclusion of sand in the water, the screw pumps are insensitive to water pollution and can work even with highly contaminated and even viscous media. This is one of the most critical parameters for many well owners, where even coarse filters cannot cope.
Fig. 2 Screw pumps - one of the productive types of equipment Compactness is another advantage that auger pumps for wells have. Usually these are submersible pumps, the geometrical parameters of which coincide with the parameters of the well. Most often, the size of the cylindrical body of the equipment does not exceed 12-15 cm in diameter. At the same time, due to the principle of operation - the creation of centrifugal force and turbulence in the working chamber, the screw units show high productivity.
The latter directly depends on the speed of rotation of the screw: the higher it is, the more water the unit can pump over per unit of time. Standard models for home use are able to maintain a stable water level in the system at around 1500-2000 liters of fluid per hour.
Disadvantages of screw pumps
This equipment has a number of disadvantages, which you also need to know about before choosing screw models:
- high price;
- fixed working volume;
- the inability to work "idle".
Choosing pumps for dirty water screw type, the user must be willing to pay a larger amount to the seller compared to others standard views equipment. average cost one model, depending on the manufacturer, is several hundred dollars for imported equipment. You can take and domestic models, for example "Kid", "Vodomet", "Belamos" and others. But the market leaders both in Russia and abroad are foreign trade marks such as Grundfos, Gadrena, Aquatica, Werk and others.
Equipment classification
Rice. 3 Standard and submersible screw pumps All screw pumps for wells are divided into standard and submersible. The former are suitable for installation in shallow wells and boreholes, for example, for the extraction of water in sandy aquifers... Such models are less efficient, and are usually installed at a depth of no more than 20-25 meters. The borehole pump has a more elongated body and auger and is intended for installation in artesian wells, the drilling of which reaches several hundred meters in depth. Such models are distinguished by higher performance and, accordingly, a higher price.
In response to the question of which screw pump to choose for the well, it is necessary to take into account the parameters of the hydraulic structure. The depth of the water mirror, as well as the facility's need for water supply, are the main technical factors affecting the choice of the unit. The power of the equipment itself should also be taken into account, since it will require a constant power supply to operate.
Deep and standard electric auger pumps consume on average 1.5 kW of energy per hour, which will allow them to be connected to a standard 220V power source. But manufacturers recommend allocating a separate source of electricity for pumping equipment and protecting it additionally with a circuit breaker.
Screw pumps are a volumetric pumping technique that creates a head due to the fact that the liquid is displaced by the rotor, which rotates around the stator. As a rule, screw devices belong to the category of gear rotary devices that are made on the base.
The first screw-type models appeared on the market in the 1920s, and literally one decade later, they won their place in industrial production, in textile and tobacco plants, in the metal processing and waste processing industries. In the oil industry, screw technology began to be used in the late 80s of the last century.
1 Types and device of screw technology
By the type and structure of the rotor, there are three main types of screw pumps:
- single-screw pumps;
- twin-screw pumps;
- three-screw pumps.
Let's consider each in more detail. The single-screw pump is a horizontal type positive displacement technique. Single screw pump in standard configuration Is a static rubber cage with a two-thread screw surface and a single-thread metal screw. When the screw rotates in the cage, liquid is sucked into the created cavities and moves along the axis to the injection area.
Apparatus with two screws are mainly used for pumping marine, fresh or mineral waters... At the same time, there is a separate class of special devices with two screws for viscous liquids - this is a technique for fuel oil. They will differ in a single mechanical seal, a heating jacket and durable steel for the manufacture of housings.
Technical screw pump - used for pumping non-aggressive substances, with lubricity without abrasive and mechanical impurities. Lubricity limits the viscosity to a minimum value. According to the maximum viscosity, the limitation occurs due to the power of the electric pump itself.
1.1 Pump screw and screw - the main difference
Since both types of technology can be attributed to displacing type devices, the different nature of the action of the working body classifies the screw equipment as dynamic, due to the screw (germ) pair, that is, the stator and the rotor.
The screw eccentric screw technology is indispensable for pumping inhomogeneous viscous materials with impurities of various kinds and calibers. They are self-priming and do not create ripple or interruption in flow.
1.2 Principle of operation of the screw pump
The structural elements of any screw technology include the following main details:
- geared motor drive;
- transitional rack;
- a gerotic (screw) pair, which consists of a stator and a rotor;
- outlet pressure branch pipe;
- camera;
- hinge;
- device for shaft sealing.
At the same time, the stator is made of elastomer, inside the stator there is a rotor, which is a helical metal element... The suction effect creates a rotation of the rotor, which changes the volumes of the cavities between the rotor and stator. The fluid gradually moves along the rotor axis, the pressure changes, and a head is created.
The body, screw and shaft of pressure vessels can be made of cast iron, carbon and stainless steel AISI 304/316/420, XM 19 or 17 4 PH, nickel-aluminum bronze or Hastelloy, Inconel or titanium. Many devices have built-in dry-running protection with ATEX technology.
1.3 The principle of operation of the screw pump (video)
1.4 OVN model
The OVN series of screw technology is used for pumping viscous materials. For example, the OVN4-2.5 / 5 marking means that it is:
О - apparatus for dairy production;
VN - screw pressure apparatus (pump);
4 - capacity volume in liters per 100 rotor revolutions;
2.5 - the number of cubic liters per hour (productivity);
5 – Atmosphere pressure apparatus.
V standard version production equipment can withstand temperatures up to 80 ° C, is completed with a standard mechanical shaft seal, and a housing made of stainless steel AISI 304.
On special order, there is a version that can withstand operation at temperatures up to 140 ° C, with a bypass for the possibility of dosing materials or with a fitting that allows the use of a CIP washer.
In total, there are twelve models in the OVN series with different characteristics: OVN-8-4.0 / 5, OVN-8-6.0 / 5, OVN-4-1.5 / 5, OVN-4-2.5 / 5, OVN-2-1.5 / 5 , OVN-2-0.7 / 5, OVN-M, OVN-6-3.5 / 5, OVN-6-5.0 / 5, OVN-8-3.0 / 5 and OVN-6-2 , 5/5.
2 Selection and maintenance of screw technology
To select a screw technology that the best way suitable for the needs of your production it is worth considering some design features... To determine whether, for a start, it is worth determining the type of apparatus you need, on which the performance indicator in cubic meters per hour or liters per minute will depend.
Then determine the required pressure level and the height of the liquid column in the area of the nozzle, the so-called NPSN indicator. In addition, you need to take into account the indicators chemical composition, density and viscosity, temperature and acid-base balance of the pumped substances. In addition, take into account the amount of abrasives and the possible presence of solid particles in the composition of the pumped material.
Well, do not forget to take into account the voltage and frequency of the power supply, and the type of transmission mechanism from the engine to the pump. The repair kit with the most necessary spare parts included in the list of the device's equipment will be of great help.
A PCP repair kit usually consists of a replacement working screw and a rubber gasket. Therefore, when the auger is worn out, it can be replaced independently without the need to contact the service department.
2.1 Applications
Screw technology is used in many areas of industrial production and for domestic needs. Among the main types of screw-type pressure equipment are:
- screw pump for water ( various variations centrifugal pump-, pneumatic screw pump, submersible pump);
- food screw pump (milk, butter and fat, confectionery and others);
- apparatus for the pharmaceutical and chemical industries;
- equipment for the oil and gas and petrochemical industries;
- equipment for power plants;
- equipment for the marine and shipbuilding industry.
The increased level of chemical and mechanical resistance to various non-abrasive inclusions and viscous elements that may be present in the liquid is due to the elastomeric composition of the stator housing. In addition, it is the composition of the stator housing that determines the maximum permissible temperature range with which the screw technology can work.
For example, in the petroleum industry, housings are made of NBR elastomer, which can withstand temperatures up to 80 ° C. In screw technology for general industrial purposes, EPDM and HYPALON materials are used, which are able to operate at temperatures up to 120 ° C. And in the chemical industry, a rubber elastomer of the FKM type is used, which can withstand temperatures up to 150 ° C.
Screw pumps are widely used in the field of providing private houses and cottages clean water from a well or well.
Every home owner knows that after purchasing real estate, 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 correct 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 deservedly popular among amateurs out-of-town rest on your site, as well as among the owners of cottages and houses due to ease of use and ease of installation. In addition, unlike a surface pump, the screw pump is distinguished by its versatility in supplying water from a great depth.
The principle of the screw pump.
The operation of screw pumps is based on the concept of an Archimedes screw.
Progressing Cavity Pump Video
Progressing Cavity Pumps are good for generating high enough pressures with little fluid flow. Screw pumps are widely used in recent times, having found the greatest popularity in providing water from wells to private houses and cottages.
The most widely used screw pumps are used in the chemical industry for pumping aggressive chemical media.
Screw pumps consist of one or several pairs of engaging screws with a special threading profile, which are placed with small gaps in the body bores. A screw pump can contain only one screw or auger, but such pumps have not found application in hydraulic drives.
A schematic representation of the meshing screws in a three-screw pump is shown in Fig. 29, a structural diagram of the screw pump in Fig. 30
The central leading screw (rotor) 1 and two side driven screws (closures) 3 have a cutting profile, with which, engaging, they roll relative to each other, forming, together with the surfaces of the bores in the housing 4, hermetically separated from the suction and discharge lines of the chamber ... When the screws rotate, these chambers are transferred along the rotor axis (like a liquid nut) from the suction zone to the discharge zone, where the liquid that filled them is displaced. Thanks to this principle of operation, the pump theoretically creates a smooth flow of liquid and a low level of noise in operation. This is one of the main advantages of this type. The driven screws rotate under the action of forces and are not loaded with torque, and the entire pumping unit of the pump is well balanced.
Technical characteristics of the pump
- The range of flow rates is also very wide - there are small pumps that develop a flow of about 3 l / min, and large ones - up to 6000 l / min;
- Working pressures for three-screw pumps with a flow rate of up to 100 l / min can reach 10 ... 25 MPa, and for large standard sizes, the working pressure does not exceed 4 ... 6.3 MPa;
- Twin-screw pumps are usually designed for small flows - up to 40 l / min and relatively low pressures - 4 ... 6.3 MPa.
Screw pumps are capable of operating at a high speed of 3000 ... 6000 rpm and above;
Disadvantages of a screw pump
The disadvantage of screw pumps is:
- the impossibility of regulating their working volume;
- the difficulty of aggregating with each other and with pumps of other types;
- Worse than the rest, overall and weight indicators.
Progressing Cavity Pump Application
Screw pumps have not received wide distribution in hydraulic systems of machines, as the main ones, and are used mainly in drives of some metal-cutting hundred ncov and presses as auxiliary - to create high feeds at idle. And also in installations for cooling and filtration of working fluid.
Screw pump
Internal organization three screw pump
Screw or screw pump - a pump in which the creation of the pressure of the pumped liquid is carried out due to the displacement of the liquid by one or more helical metal rotors rotating inside the stator of the corresponding 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 the teeth.
Screw design in a twin screw pump. The liquid moves along the pump axis
Principle of operation
Liquid is pumped by moving it along the screw axis in the chamber formed by the helical grooves and the surface of the body. The screws, with their helical protrusions entering the grooves of the adjacent screw, create an enclosed space, preventing the fluid from moving backward.
Application area
Designed for pumping liquids varying degrees viscosity, gas or steam, including mixtures thereof.
These pumps can operate at pressures up to 30 MPa.
First introduced into practice in 1936, screw pumps have simple design, can work in the presence of mechanical impurities and with viscous fluids, which is necessary when solving various practical problems. A large number of PCP units are used to remove water from wells producing methane from coal beds, 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
A cylindrical or conical resilient body is sometimes used to improve seal quality and reduce leakage. In the latter case, the conical screw is pressed by a spring, and sometimes also by the pressure of the pumped liquid. However, resilient casing pumps are capable of withstanding lower pressures than metal casing pumps. For pumps with tapered 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 solid inclusions in the liquid;
- like other positive displacement pumps, screw pumps are capable of self-priming liquid;
- opportunity to get high pressure at the outlet without many stages of injection;
- good balance of the mechanism and, as a result, low noise level during operation.
disadvantages
- complexity and high price manufacture of the pump;
- unregulated working volume;
- just like other types of positive displacement pumps, screw pumps cannot be run dry without the pumped liquid, since in this case the coefficient of friction of the pump parts increases and the cooling conditions deteriorate; as a result, the pump can 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", "Yanus-K", 2003 - 544 p.
2. Lee James, Nickens Henry, Wells Michael. Operation of watering gas wells. Technological solutions for removing fluid from wells / Translated from English. - M .: OOO "Premium Engineering", 2008. - 384p., Ill. (Industrial engineering).
see also
- PCM Screw Pumps
Notes (edit)
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See what a "Screw pump" is in other dictionaries:
Rotary lobe pump with working bodies in the form of one leading and usually two driven screws, which are in engagement. When the screws rotate, the liquid cut off in the hollows of the screw thread moves along the screws and is pushed into the discharge pipe ... Big Encyclopedic Dictionary
screw pump- Rotary rotary pump with displacement of the liquid medium along the axis of rotation of the working bodies. [GOST 17398 72] Unacceptable, not recommended worm pump Topics pump EN screw pump DE Schraubenspindelpumpe FR Pompe a vis ... Technical translator's guide
Rotary lobe pump with working bodies in the form of one leading and usually two driven screws, which are in engagement. When the screws rotate, the liquid cut off in the hollows of the screw thread moves along the screws and is pushed into the discharge pipe ... encyclopedic Dictionary
screw pump- sraigtinis siurblys statusas T sritis automatika atitikmenys: angl. 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 vane pump the movement of the working bodies (screws). In the building of V. n. there are one leading and one, two or four driven (sealing) screws. The gap between the screw threads and the housing is small. Line of engagement of screws within one pitch ... ... Big Encyclopedic Polytechnic Dictionary
A hydraulic machine, the working element of which is a screw: serves to supply fluid, including those with increased viscosity. V. n. is a kind of rotary pumps, also called worm pumps. In the building of V. n. available ... ... Great Soviet Encyclopedia
Pump, screw- Screw pump Ndp. Worm pump Rotary rotary pump with displacement of a liquid medium along the axis of rotation of working bodies See all terms GOST 17398 72. PUMPS. TERMS AND DEFINITIONS