RU2395720C1 - Multistage pump unit - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed device is intended for pumping over of gases, liquids and multi-phase mixes. Device comprises at least two pump stages fitted successively on common shaft. Every said stage represents vane-type positive-displacement pump and comprises rotor 8 arranged inside housing 6 with its inner surface formed by two pairs of symmetric different-radius circular arcs and sections of smooth transition from larger diametre circular arcs to smaller diametre circular arcs. Said rotor is limited by side covers on its faces. Lateral inlet cover has at least two main inlet openings 15 and at least two additional inlet openings 16, while at least two main outlet openings 17 and at least additional outlet openings 18 are made in opposite cover. Flat sectors of inlet cover are turned relative to flat sectors of outlet cover through slant angle. Covers are secured on housing 6 with said flat sectors arranged opposite aforesaid smooth transition sections of rotor inner surface. Stator 7, rotor 8, vanes 10 and side covers are made from hard alloys.

EFFECT: multistage design allows increasing operating pressure multiply with number of vanes by reducing load on every stage.

4 dwg

Description

The invention relates to volumetric type pumps, and more particularly to multi-stage casing pumps designed for pumping gases, liquids and multiphase mixtures that do not have lubricating properties, with a high content of mechanical impurities and / or having a high viscosity, for example, formation fluids of oil fields.

Known submersible centrifugal multistage pump with angular contact bearings, containing a set of stages assembled in a cylindrical housing (RF patent No. 2250392, F04D 13/10, 2005). This design eliminates the distortion of the contacting surfaces due to the centering of each impeller relative to the guide apparatus, reducing their wear. The pump is designed for pumping liquids with abrasive particles, as prevents wear of the rubbing surfaces of the hubs of the guide vanes, reduces the vibration of the rotor by centering it relative to the guide vanes and unloading the radial bearings of the pump shaft.

However, the design flaws are technological difficulties and laboriousness in manufacturing, which requires special processing methods and expensive equipment, low heads per stage and, as a result, large dimensions (length) of the pump, as well as the impossibility of pumping gases and gas-liquid mixtures and mixtures with high viscosity.

Known vane oil pump containing a housing, a rotor with radial grooves in which are placed the working plate, constantly in contact with the internal profiled surface of the housing during rotation of the rotor, between which are located the pumping chamber of the mixtures (RF patent No. 2191926, F04C 2/344, 2002).

The body cavity is made in the form of a cylindrical surface formed by two pairs of symmetrically arranged arcs with different radii and smooth transitions from arcs of a larger radius to arcs of a smaller radius. Surfaces of equal radii are located opposite each other. The pump rotor has a cylindrical surface formed by a circle with a radius smaller than a small radius of the inner surface of the housing. Working plates with a number of at least 8 are spring-loaded in radial grooves with the possibility of radial movement, and grooves are made on the inner surface of the groove connecting the volume of the groove under the working plate with pumping chambers. The working plates are made of wear-resistant polyurethane with the addition of a mixture of molybdenum disulfide, oxidized graphite, etc. The inner surface of the housing cavity and sliding bearings are made of the same polyurethane, and the side covers are made of steel.

The disadvantages of the known technical solutions are as follows:

- the impossibility of creating a multi-stage pumping device based on this pump;

- the inability to pump media with a high content of mechanical particles, since the design does not provide a flowing flow of the pumped liquid and contributes to the formation of stagnant zones;

- the known design of the pump does not allow to manufacture all rubbing parts only from hard alloys, for example titanium carbides, tungsten or silicon, the hardness of which is higher than the hardness of mechanical particles in the pumped liquid.

Closest to the claimed is a submersible multistage centrifugal pump for oil production, which is a hydrodynamic machine (RF patent No. 232,6244, F04D 13/10, F04D 29/62, 2008).

The disadvantages of this design are:

- the inability of the centrifugal stages of the pump to pump media with a large amount of mechanical impurities for a long time due to wear of pump elements made of materials with low hardness, since the pumped medium constantly changes its direction of movement and, as a result, hydroabrasive wear appears. In addition, the pump has a large number of stagnant zones and various cavities in which mechanical impurities accumulate, complicating disassembly during repair;

- the inability to reduce the flow rate of the medium by decreasing the pump speed without loss of pressure, as a result, the need for throttling, which reduces the efficiency;

- the inability of the centrifugal stages of the pump to pump gases and gas-liquid mixtures with a free gas content of more than 50%, since the supply is interrupted;

- the inability of the centrifugal stages of the pump to pump mixtures with high viscosity, since this greatly reduces the efficiency and pressure-flow characteristic (at a certain viscosity of the pumped mixture, the pump stops working), and also leads to the rapid deposition of various mechanical impurities in the flow cavities;

- low head pressure leads to a large length of the pump, which affects the manufacturability of manufacturing, complicates the assembly and leads to high consumption of materials;

- in the process of pumping is a constant mixing of the medium, which leads to the formation of stable emulsions, complicating the further separation of liquids;

- pumps are difficult to manufacture, require special processing methods and sophisticated equipment.

The technical problem that is solved by the invention is to expand the functionality of the device by using it for pumping gases, liquids and multiphase mixtures that do not have lubricating properties, with a high content of mechanical impurities and / or having a high viscosity, as well as the possibility of regulating the flow of pumped media in the range from 0.1 to 5 of the nominal values without significant loss of operating pressure and efficiency, while increasing manufacturability niya elements of the device.

The essence of the technical solution lies in the fact that in a multistage pumping device comprising at least two stages of pumps placed sequentially on a common shaft, according to the formula, each stage is made in the form of a volumetric vane type pump with a safety valve and a seal between the shaft and the rotor installed with the possibility of axial movement on the shaft, and includes a rotor with working plates moving in its grooves and located inside the housing, the inner surface of which is formed by knowing in pairs of symmetrically arranged arcs of different radii and smooth transition sections from arcs of a larger radius to arcs of a smaller radius, and bounded from the ends by side caps, at least two main inlet windows and at least two additional inlet windows are made in the side inlet cover, and at least two main outlet windows and at least two additional outlet windows are made in the opposite cover, with each at least two windows located inside the flat sector from the center angles calculated by the formula: 90 ° -360 ° / n, where n is the number of working plates. These flat sectors of the side inlet cover are deployed relative to the flat sectors of the side outlet cover at a right angle, and these side covers are fixed to the housing with the placement of these flat sectors opposite the smooth transitional sections of the inner surface of the housing. The stator, rotor, working plates and side covers are made of carbide.

In contrast to the prototype, the claimed device includes several stages, which are volume-type vane type pumps with all the advantages compared to centrifugal ones, namely, the flow rate is proportional to the shaft speed at constant outlet pressure, the ability to pump compressible media, high efficiency and high pressure on the step. At the same time, as well as a centrifugal pump, the inventive device allows you to create a certain design pressure at each stage, as a result, reducing loads and the possibility of reducing the accuracy of manufacturing pump parts.

With equal diametrical dimensions, the step of the volumetric type has great advantages, because their pressure is an order of magnitude and higher than that of a centrifugal stage, which can significantly reduce the dimensions of the installation.

The claimed design of each stage allows the transfer of multiphase viscous mixtures with a high content of mechanical impurities, due to the elimination of the formation of stagnant zones inside the stage and the possibility of using carbide materials for the manufacture of rubbing parts of the pump, namely all parts that form the working chambers.

The sealing between the shaft and the rotor can significantly reduce internal leakage, preventing the flow of medium between the steps in the gap of the movable connection between them, which increases the efficiency and flow-pressure characteristics of the inventive pumping device.

Each stage in the form of a volumetric vane type pump is equipped with a safety valve that relieves excess pressure and is configured for a pressure drop equal to the maximum possible pressure that the pump stage can develop, while maintaining the required durability. As a result, overload or breakdown of any stage and the entire device as a whole is excluded.

The vane pump includes a rotor with axial movement on the shaft, with working plates moving in its grooves, and located inside the stator, the inner surface of which is formed by two pairs of symmetrically arranged arcs of different radii and smooth transition sections from arcs of a larger radius to arcs of a smaller radius, and bounded at the ends by side covers, wherein said flat sectors of the side inlet cover are offset relative to the flat sectors of the side outlet cover by an angle of 90 °, wherein It seemed side covers fastened on the stator with placing said planar sectors opposite the arcuate transition sections the inner surface of the stator. The stator, rotor, working plates and side covers are made of carbide.

The essential features are that at least two main inlet windows and at least two additional inlet windows are made in the side inlet cover, and at least two main outlet windows and at least two additional outlet windows are made in the opposite side outlet the lid, they allow the predominantly axial direction of movement of the pumped mixture, which contributes to a better flushing of the entire internal volume of the pump, eliminating the formation of stagnant zones, and akzhe uneven wear upper working plate edges due to the lack of radial inlet and outlet ports on the stator.

The implementation of additional inlet windows on one of the side covers, and additional outlet windows on the opposite side cover in the areas of volume changes between the grooves of the rotor and the lower plane of the plates, allows pumping an additional amount of liquid and flushing the space under the plates, as well as eliminating unproductive operation on the rotor - obtaining grooves, especially if the rotor is made of hard alloy.

When each at least a pair of windows is located inside a flat sector with central angles calculated by the formula: 90 ° -360 ° / n, where n is the number of working plates, and also if these flat sectors of the side inlet cover are deployed relative to the flat sectors of the side outlet cover at a right angle, and these side covers are mounted on the housing with the placement of these flat sectors opposite the smooth transitional sections of the inner surface of the stator, provides movement of the working plates in the grooves of the rotor only in those cases when the differential pressure does not act on the front and rear planes of the working plates and, accordingly, provides a static position of the working plates when the pressure differential is in effect. This makes it possible to practically eliminate the ingress of solid mechanical particles into the contact zone of the “plate-groove of the rotor” pair and to reduce the friction forces in this pair.

The execution of all the rubbing elements of the pump, forming the working chambers (stator, rotor, working plates, side covers), from hard alloys, for example titanium carbides, tungsten or silicon, makes it possible to pump non-lubricating media with a high content of mechanical particles and / or having a high viscosity.

The inventive design of the device is illustrated as follows.

Figure 1 shows a General view of a multi-stage pumping device of the claimed design, figure 2 - view a with two stages in figure 1, figure 3 shows a section bB in figure 2, and figure 4 shows the stage of the claimed devices in isometry in figure 1.

A multistage pump contains a set of sequentially assembled identical steps 1 installed in a cylindrical housing 2 on a common shaft 3, including a safety valve 4 and a seal 5.

Each stage 1 is a vane pump and includes a housing 6, inside of which a stator 7 is rigidly mounted. The rotor 8 is made with radial grooves 9 along which the working plates 10 having a front 11, rear 12 and lower 13 plane move. A pair of main inlet windows 15 and a pair of additional inlet windows 16 are made in the side inlet cover 14.

A pair of main outlet windows 17 and a pair of additional outlet windows 18 are located on the side outlet cover 19. Each pair of windows 15, 16 and 17, 18 on both covers 14 and 19 is located inside the flat sector B with central angles Y and σ, which are calculated by the formula : 90 ° -360 ° / n, i.e. may vary in size. Moreover, n is the number of working plates 10, which can vary from 5 to 19. The indicated sectors B of the covers 14 and 19 are offset by an angle of 90 ° relative to each other.

The working chamber 20 is formed by the inner profile surface of the shell or stator 7, the outer surface of the rotor 8, the front 11 and rear 12 by the planes of the plates 10 and is axially limited by the end surfaces of the side covers 14 and 19.

The lower sub-plate chamber 21 is formed by the surface of the radial groove 9 of the rotor 8, the lower plane 13 of the working plates 10 and is axially limited by the end surfaces of the covers 14 and 19.

The inner surface of the stator 7 is formed by two pairs of symmetrically arranged arcs of different radii r and R, limited by the central angles α and β and smooth transition sections 22.

Flat sectors In the side covers 14 and 19 are located opposite the transition sections 22 of the inner surface of the stator 7. Between the steps 1 are the spacer sleeve 23.

The leading link in the pump is a common shaft 3, mounted on sliding bearings 24, compressed into a common package with steps 1 in a cylindrical housing 2, by means of end parts 25 and 26, and the shaft 3 is mated to the rotor 8 of each stage 1 with the possibility of axial movement and has in this mate seal 5.

Each stage 1 of a multistage pumping device operates as follows.

When the rotor 8 rotates, centrifugal forces press the plates 10 installed in the radial grooves 9 against the inner surface of the stator 7, which is rigidly connected to the housing 6. Between the rotor 8, the stator 7, the covers 14 and 19 and each front 11, the back 12 are the planes of each pair of plates 10 there are working chambers 20, the number of which is equal to the number of blades 10. Inside sectors B with central angles γ and δ are the main and additional inlet and outlet windows 15, 16 and 17, 18, respectively, through which the multiphase pumped mixture with mechanical it enters the working chambers 20 and into the sub-plate chambers 21, then leaves them.

When the rotor 8 rotates, the volumes of the working chambers 20 in the sections of the profiled surface of the stator 7 change, since the plates 10 at these moments move relative to the grooves 9 of the rotor 8, and through the main inlet windows 15 and additional inlet windows 16, the pumped mixture enters the working chambers 20 and sub-plate chambers 21, respectively. Further, when the rotor 8 rotates in the sections of the profiled surface of the stator 7, limited by angles α and β, the volumes of the working chambers 20 and the sub-plate chambers 21 remain constant, the pumped mixture moves to the main outlet windows 17 and additional outlet windows 18. When the plate 10 reaches the transition section the profiled surface of the stator 7, limited by the angles γ and δ, the movement of the plate 10 into the groove 9 of the rotor 8 begins, while the pressure of the mixture from all sides of the plate 10 becomes the same (the plate exerts I entirely in the discharge line) and the displacement of the pumped fluid from the working chambers 20 and podplastinchatyh chambers 21 in the pressure line of the pump through outlet ports 17 and additional outlet ports 18, respectively.

Thus, the multiphase mixture containing mechanical impurities is pumped not only by the working 20, but also by the sub-plate chambers 21, and the working plates 10 move relative to the grooves 9 of the rotor 8 only in cases when they are not affected by the pressure drop, and accordingly the plate 10 fixed relative to the radial grooves 9, when they are affected by a pressure differential.

The inventive device operates as follows.

When the shaft 3 rotates, the pumped medium moves from one stage 1 to another, sequentially installed in a common set (not shown), increasing the pressure of the pumping device in proportion to the number of stages. The seal 5 prevents the flow of medium between the steps in the gap between the shaft 3 and the rotors 8.

Since the stage of the device is a volumetric vane type pump, under certain conditions an uneven distribution of pressure between stages 1 is possible and, as a result, overload or breakdown of any stage and, accordingly, the entire device. To prevent this, each stage 1 has a safety valve 4, which relieves the excess pressure, thereby limiting its value for each stage 1 and ensures uniform loading of the multi-stage pumping device.

Thus, the claimed device allows to increase the working pressure of the pumped medium by a multiple of the number of stages and has the advantages of pumps as a volumetric type (flow rate is proportional to the shaft speed at constant working pressure, the ability to pump compressible media, high efficiency and high pressure per stage), as well as multistage pumps (a certain design head for each stage and, as a result, a decrease in loads).

Claims (1)

A multi-stage pump device comprising at least two stages of pumps arranged sequentially on a common shaft, characterized in that each stage is made in the form of a volumetric vane type pump with safety valves and a seal between the shaft and the rotor mounted axially movable on the shaft, and includes a rotor with working plates moving in its grooves, located inside the housing, the inner surface of which is formed by two pairs of symmetrically arranged arcs of different radii and smooth transition sections from arcs of a larger radius to arcs of a smaller radius, and bounded from the ends by side covers, wherein at least two main inlet windows and at least two additional inlet windows and at least two main inlets are made in the side inlet cover exhaust windows and at least two additional exhaust windows are made in the opposite cover, with each at least two windows located inside a flat sector with central angles calculated by the formula: 90-360 ° / n, where e n is the number of working plates, and these flat sectors of the side inlet cover are deployed relative to the flat sectors of the side outlet cover at a right angle, and these side covers are mounted on the housing with the placement of these flat sectors opposite the smooth transition sections of the inner surface of the housing, and the stator, rotor, working plates and side covers are made of carbide.

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