RU119823U1 - MULTI-STAGE CENTRIFUGAL PUMP - Google Patents

Abstract

A multistage centrifugal pump containing a stage made of an impeller mounted on a shaft and made in the form of a driving disk, a driven cover disk and blades that are fixed between the driving disk and a driven cover disk, and from a guide vane made in the form of a paddle cover disk, cylindrical cage and blades, the cylindrical cage of the guide vane is made with an annular wall located transversely, an impeller and a paddle cover disk are installed inside the cylindrical cage, and the blades are fixed in the guide vane between the annular wall of the cylindrical cage and a paddle cover disc, while the ratio of the number of blades to the number of blades is selected in the range 0.88-1.75, the ratio of the diameter of the impeller and / or the diameter of the bladed cover disk to the inner diameter of the cylindrical cage above them is in the range of 0.92-0.99, each of the impeller blades is made with an angle coverage 100-1 50º, each of the blades of the guide vane is made with an angle of coverage of 90-150º, the angle of entry of the blade is selected in the range of 4-12º, and its exit angle is 55-95 °.

Description

The utility model relates to hydraulic engineering, mainly to the design of the stage of a low-flow submersible centrifugal pump with a lateral outlet in the form of a guiding apparatus (AN) and can be used in the production of formation fluid, water and other liquid media from wells.

A known design of a multistage centrifugal pump, made according to the "classical" scheme and used in various fields of technology (feed pumps, pumps for aircraft and rocket engines, pumps for the nuclear and chemical industries, etc.), which provides for the location of the outlet in the form of a guide apparatus above the centrifugal wheel (Stepanov A.I. "Centrifugal and axial pumps" - M., GNTI Engineering literature, p. 131, Fig. 7.17). This design of the pump provides lower hydraulic losses (large values of the efficiency of the pump), but low vibrational activity of the pump.

Also known is a multistage centrifugal pump containing a stage made of an impeller mounted on a shaft and made in the form of a drive disk, a driven cover disk and vanes that are fixed between the front surface of the drive disk and the driven cover disk, and from a guide apparatus made in the form blade cover disk, a cylindrical cage and blades, moreover, the blade cover disk of the guide apparatus is mounted on the side of the rear surface of the driving disk of the impeller, cyl The casing of the guide vane is made with an annular wall located transversely; inside the cylindrical cage, the impeller and the blade cover disk are installed, the blades are fixed in the guide device between the ring-shaped wall of the cylindrical clip and the blade cover disk, certain ratios of parameters and geometric dimensions of the blades and blades are selected (see Patent of the Russian Federation No. 2161737 IPC 7 F04D 1/06, F04D 13/10, publ. 10.01.2001).

In the known design of a multistage centrifugal pump, the problem of optimizing the shape of the blades and their inlet and outlet angles is solved to increase the pressure and efficiency. This allows you to increase the efficiency, but slightly, but does not allow to obtain a sufficiently high pressure value.

A characteristic feature of multistage submersible centrifugal pumps is a large number of stages, amounting to 300-400 units, which is associated with a large depth of formation fluid (1500-2500 m). As a result of this, the pumping unit has a large length (up to 25 m), which leads to its cost increase and the complexity of its operation. Therefore, in submersible multistage centrifugal pumps, often to the detriment of efficiency, they tend to increase the head of the stage by using the maximum diameter of the centrifugal wheel D ₂ due to the lateral location of the outlet. In addition, for submersible pumps there is no requirement for high cavitation qualities of the stage, which leads to a narrowing of the inlet area of the centrifugal wheel by reducing the sizes D ₀ (diameter of the entrance to the impeller) and D ₁ (diameter of the blade at the inlet along the midline), b ₁ (blade width at the inlet). All this, along with other features, distinguishes submersible low-flow pumps in a special class, for which normative data developed for centrifugal pumps of the "classical" form are unacceptable.

The objective of the utility model is to improve energy performance by increasing pressure without compromising efficiency.

The specified technical result is achieved by the fact that in a multistage centrifugal pump containing a stage made of an impeller mounted on a shaft and made in the form of a drive disk, a driven cover disk and vanes that are secured between the drive disk and the driven cover disk, and from the guide vane made in the form of a blade cover disk, a cylindrical cage and blades, the blade cover disk of the guide apparatus is installed on the side of the rear surface of the working drive disk wheels, a cylindrical cage of the guide apparatus is made with an annular wall arranged transversely, an impeller and a blade cover disk are installed inside the cylindrical cage, and the blades are fixed in the guide device between the ring-shaped wall of the cylindrical cage and the blade cover disk, while the ratio of the number of blades to the number of blades is selected in the range of 0.88-1.75, the ratio of the diameter of the impeller and / or the diameter of the blade cover disc to the inner diameter of the cylindrical wallpaper s above them - in the range of 0.92-0.99, each of the blades of the impeller is made with a coverage angle of 100-150 °, each of the blades of the guide apparatus is made with a coverage angle of 90-150 °, the angle of entry of the blade is selected in the range of 4-12 °, and its exit angle is 55-95 °.

The essence of the utility model is illustrated by the attached figures.

Figure 1 shows two successive stages of a multistage centrifugal pump.

Figure 2 presents the impeller of a multistage centrifugal pump.

Figure 3 - the guide apparatus of a multistage centrifugal pump.

Figure 4 presents the pressure characteristics (pressure and efficiency versus flow) for the claimed device and analogue according to the patent of the Russian Federation No. 2161737.

Figure 5 shows the test results of low-speed centrifugal pumps with different values of the blades and the angle of the impeller.

A multistage centrifugal pump contains at least two stages 1. Steps 1 are located along the shaft (not shown in the drawing) in series. The stage 1 is made of the impeller 2 and the guide apparatus 3. The impeller 2 is mounted on the shaft and is made in the form of a drive disk 4, a cover disk 5 and blades 6. The blades 6 are fixed between the drive disk 4 and the cover disk 5. The guide device 3 is made in in the form of a blade cover disk 7, a cylindrical sleeve 8 and blades 9. The shoulder cover disk 7 is installed on the side of the rear surface 10 of the driving disk 4 of the impeller 2. The cylindrical sleeve 8 is made with an annular wall 11 located transversely. Inside the cylindrical cage 8, the impeller 2 and the blade cover disk 7 are installed. The blades 9 are fixed in the guide apparatus 3 between the annular wall 11 of the cylindrical ring 8 and the blade cover disk 7.

To reduce the frictional forces arising from the rotation of the impeller 2, washers 12, 13, 14 of antifriction material are used in the design, acting as individual bearings.

The ratio of the number of Z _K blades 6 to the number of Z _an blades 9 is selected in the range Z _K / Z _an = 0.88-1.75, the ratio of the diameter D ₂ of the impeller 2 and / or the diameter of the blade cover disk 5 to the inner diameter D _{K of the} cylindrical the clips 8 above them are selected in the range D ₂ / D _K = 0.92 ÷ 0.99. Each of the blades 6 of the impeller 2 is made with a coverage angle θ _k = 100-150 °.

Each of the blades 9 of the guide apparatus 3 is made with a coverage angle θ _en = 90-150 °, the entry angle β _{3l of the} blade 9 is selected in the range β _3l = 4-12 °, and its exit angle β _{4l is} selected in the range β _4l = 55- 95 °.

As studies have shown, with the listed parameters of the impeller 2 and the guiding apparatus 3, minimal hydraulic losses and an increase in pressure and efficiency are achieved.

Works multistage centrifugal pump (Fig.1-3) as follows.

The impeller 2 is driven by a pump shaft. The pumped liquid enters the paths between the blades 6 of the rotating impeller 2 and moves from its center to the periphery. In this case, the impeller 2 creates a pressure head of the pumped liquid, both due to the circulation forces and due to the Coriolis forces. By setting the outer diameter of the blades 6 D ₂ as high as possible, at which D ₂ / D _k = 0.99, it is possible to increase the pressure of the stage. By choosing the number of blades 6 and blades 9, satisfying the ratio Z _K / Z _an = 0.88 ÷ 1.75, it is possible to establish the necessary value of the area at the entrance to the guiding apparatus and, as a result, ensure that the pump operates at maximum efficiency. The implementation of the blades 6 with a coverage angle θ _k = 100 ÷ 150 ° allowed to expand the flow channel and reduce hydraulic losses.

Next, the fluid enters the channels of the guide apparatus 3, in which the flow is decelerated (increasing the static component of pressure) in order to reduce losses, a turn and the direction of flow to the impeller of the next stage. By setting the angles at the inlet of β _3l and outlet β _{4l of the} blades 9, satisfying the conditions at β _3l = 4 ÷ 12 ° and β _4l = 55 ÷ 95 °, as well as the implementation of the blades 9 with a coverage angle θ _an = 90 ÷ 150 ° ensure the absence of flow separation and the absence of vortex zones, which in turn increased the pressure and efficiency of the stage.

The ratio of the number of Z _K blades 6 to the number of Z _an blades 9 is selected in the range Z _K / Z _en = 0.88 ÷ 1.75. This is justified by the following considerations. For low-flow pumps Z _K ≤8 due to their small size. Ensuring operation at maximum efficiency (the requirement of many oil companies) depends on the area of entry into the guiding apparatus, the value of which, in turn, is affected by the number Z _en = 3 ÷ 8, where a lower value of Z _en = 3 corresponds to Q = 10 ÷ 18 m ³ / day, and a larger value of Z _en = 8 corresponds to Q = 55 ÷ 70 m ³ / day (n = 2910 rpm = const). The number of wheel blades is Z _K = 5 ÷ 8 (lower values of Z _K correspond to lower feeds). Then: Z _K / Z _en = 0.88 ÷ 1.75. In the patent No. 2161737 the ratio Z _K / Z _en = 1.75 is given, this suggests that the geometry of one particular stage with Z _K = 7 and Z _en = 4 is considered in this patent. Expanding the range Z _K / Z _an allows _you to choose the optimal number of impeller blades and vanes of the guide vane depending on the flow rate.

The design experience of low-speed multi-stage centrifugal pumps BENZ showed that in order to increase the pressure and reduce the number of stages, it is possible to expand the range of D ₂ / D _to upward (D ₂ / D _to ) _max = 0.99, which was proved experimentally and with a positive result implemented in practice (figure 1). In the patent No. 2171737 given the ratio of D ₂ / D _to = 0.92 ÷ 0.97. Increasing the range of D ₂ / D _k to 0.99 with a fixed value of D _K allows you to increase the outer diameter of the impeller and thereby increase the head of the stage. The increase in pressure was ~ 4.6%, which in the presence of the number of stages ~ 400 will reduce their number by 18 stages, which will affect the decrease in the length of the pump, as well as its cost.

The angle of coverage θ _k = 100 ÷ 150 ° (In patent No. 2161737 the angle of coverage θ _k = 98 ÷ 104 °).

The head and efficiency of the pump depends on the density τ _{k of the} lattice of the centrifugal wheel blades τ _k ~ L _k / a _k , increasing with increasing τ _k to a certain limit, where L _k is the length of the channel and a _to is the width of the channel. To ensure the necessary density of the lattice can be both by increasing the number of blades (reduced _to a) and by increasing the channel length (L _k). The latter is achieved by increasing the angle of coverage of the blades (figure 2). The second method for low-flow pumps is in most cases more preferable, because does not lead to narrowing of the flow channels (as this occurs with an increase in the number of blades), which reduces hydraulic flow losses and significantly reduces the likelihood of clogging of the inter-blade channels. Experience in designing low-speed centrifugal pumps has shown that an increase in the angle of coverage of the blades with a corresponding decrease in the number of blades of the wheel leads to a significant increase in pressure and efficiency of the wheel. This is also proved experimentally (figure 5).

The tests carried out make it possible to recommend the angle of coverage of the blades to be selected in the range θ _k = 100 ÷ 150 °; moreover, for large flows of low-speed centrifugal pumps (Q = 60 m ³ / day), it corresponds to 100 °, and for small flows (Q = 15 m ³ / day) it corresponds to 150 °. The number of wheel blades Z _K must correspond to ensuring the density of the wheel grill τ _k = 1.8 ÷ 2.1, where

Here: D ₂ , D ₁ - the outer diameter of the wheel and the diameter of the input edges of the blades, respectively (figure 1);

β _2l , β _1l - the angle of installation of the blades at the outlet and inlet, respectively (figure 2).

The angle of coverage θ _en is selected from the condition for ensuring an uninterrupted flow in the lattice AN. For large flows of low-flow centrifugal pumps (Q = 60 m ³ / day), it corresponds to 90 °, and for small flows (Q = 15 m ³ / day) it corresponds to 150 °, i.e. θ _en = 90 ÷ 150 ° (figure 3). This statement has been successfully tested in practice. In patent No. 2171737 the angle of coverage of the vanes of the guide vane θ _en = 130 ÷ 134 °, which indicates a single step for a specific feed. The expansion of the range θ _en allows you to choose the optimal angle of coverage depending on the flow.

In the well-known centrifugal pump according to the patent of the Russian Federation No. 2161737 β _3l = 6 ÷ 12 °; β _3l = 85 ÷ 95 ° there is a drawback that involves the rotation of the flow in the AN at an angle Δβ = β _4l -β _3l = 73 ÷ 89 °, which is impossible without flow separation in the lattice. This well-known fact is well illustrated by the graph (A. Lomakin Centrifugal and axial pumps. - M. "Mechanical Engineering" 1966, p. 270, Fig. 169), which presents graphs of the maximum continuous angle of rotation of the flow in the lattice depending on the angle at the outlet of the flow from the grate (β _4L ) and the density of the grating of the blades L / t. From the graphs it follows that in the Academy of Sciences, with the recommendations of the prototype, it will have a tear-off flow regime with a actually smaller angle of exit of the stream from the AN. For this reason, in the literature on pumps it is not intended to completely unwind the flow in the lattice of the AN blades.

Statistics on the development of low-speed centrifugal pumps showed that the best results in terms of pressure and efficiency are obtained at β _3l = 4 ÷ 12 ° and β _4l = 55 ÷ 95 °.

In the described application for the invention to patent No. 2171737 are given as an illustration of the positive effect of pressure and efficiency characteristics of a centrifugal pump for oil production at a flow rate of ~ 50 m ³ / day (Fig. 4 curves C and D). Figure 4 also shows the pressure and efficiency characteristics of a centrifugal pump at about the same flow rate (curves A and B). A comparison of these characteristics shows that at Q = 50 m ³ / day, the pressure on the proposed application is higher by 43% (H = 5.85 m versus H = 4.1 m), efficiency by 2% (η = 49% against η = 48%).

Within the framework of the R&D plan, JSC BENZ developed the level 5-30. This stage was manufactured and tested at the stand of JSC "BENZ". According to the test results, test report No. 3/10 dated November 16, 2010 and Act No. 1 were issued. The geometry of this stage fully satisfies the ranges of parameters from the application. Stage 5-30 of JSC "BENZ" is one of the best on the market. The table compares the energy parameters of similar stages of competitors. It can be seen that the pressure and efficiency level 5-30 of BENZ OJSC is higher than that of competitors, which proves the effectiveness of applying the ranges of geometric parameters presented in the application of BENZ OJSC in practice.

Stage Q, m ³ / day Q _opt , m ³ / day N, m η,% BENZ 5-30 thirty 33 5.15 39 ALNAS 5-30 thirty 28 4.7 35 BORETS 5-30 thirty 39 4.8 33

Thus, the proposed design of a multistage centrifugal pump due to the optimally selected parameters and sizes of the blades, blades of the AN and their angles allows you to work at maximum efficiency, increases the pressure of the pump, reduces the likelihood of clogging of the interscapular channels of the impeller, a continuous flow is provided in the guide apparatus, which positively affects on efficiency.

Claims (1)

A multistage centrifugal pump comprising a stage made of an impeller mounted on a shaft and made in the form of a drive disk, a driven cover disk and vanes that are secured between the drive disk and the driven cover disk, and from a guide apparatus made in the form of a blade cover disk, a cylindrical cage and blades, a cylindrical cage of the guide apparatus is made with an annular wall located transversely, an impeller and shovels are installed inside the cylindrical cage full-time cover disk, and the blades are fixed in the guide apparatus between the annular wall of the cylindrical cage and the blade cover disk, while the ratio of the number of blades to the number of blades is selected in the range of 0.88-1.75, the ratio of the diameter of the impeller and / or the diameter of the blade cover disk to the inner diameter of the cylindrical cage above them is in the range of 0.92-0.99, each of the impeller blades is made with a coverage angle of 100-150º, each of the guide vanes is made with a coverage angle of 90-150º, the entrance angle is l patki selected in the range 4-12º, and its exit angle - 55-95 °.