RU2367820C1 - Centrifugal well pump stage - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to engines and pumps and can be used in well immersible pumps used in oil production. Proposed stage comprises impeller made up of drive and driven disks with vanes arranged there between, inlet and discharge guide cases. Proposed stage incorporates device to create pressure head at the impeller inlet. Aforesaid device represents multi-start screw with its hub furnished with collar rigidly jointed to discharge guide case and smoothly mating, on the suction side, the hub cylindrical section to form shaped space with the screw end face. Hub base cylindrical section features inclined thin-wall ribs with coiling direction opposite to impeller rotation, and helix angle equal to 40° to 45° and extending beyond the hub base.

EFFECT: higher efficiency.

3 dwg

Description

The invention relates to the field of pump engineering, and more specifically to centrifugal submersible pumps with limited diametric dimensions, and in particular to their working bodies. It can find application in other centrifugal pumps, which, when working with a liquid containing gaseous substances, have a small cavitation reserve.

Known stage submersible multistage pump, consisting of an impeller equipped with a driving and driven discs with blades placed between them, and a guide vane with profiled radial blades (RF Patent No. 2138691, MKI 6F04D 13/10, 1/06, 31/00, 1999 g.).

The disadvantages of the device:

- a significant depth of immersion of the pump at a dynamic level, due to the need to prevent flow stall at the moment of entry of the pumped medium into the cavity of the impeller of the first stage, due to the occurrence of vacuum in it due to the presence of a significant amount of gas in the pumped medium;

- low efficiency of the pump with significant gas content in the pumped medium due to the need to control changes in the dynamic level, and in case of a change in the latter - the need to stop the installation until the dynamic level is restored.

A known centrifugal pump stage, consisting of an impeller and fixed blades installed in the pump inlet (A.K. Mikhailov and V.V. Malyushenko. Vane pumps. - M., Mechanical Engineering, 1977, p. 126, Fig. 67a).

This device is designed to prevent swirling of the entire flow in the inlet of the pump and is not applicable in the steps of submersible borehole pumps.

A multi-stage condensate centrifugal pump is known, consisting of several stages, each of which contains an impeller with radial channels and a guiding apparatus with spiral channels, the first stage being made so that it has a transverse area of the input annular channel significantly larger than the area of the same channel of the subsequent impeller ( The source is the same, p. 250, fig. 136 and p. 126, fig. 67c).

The disadvantages of the device:

- poor performance in borehole pumps due to the small transverse dimensions of the latter, since the support created by the screw wheel is negligible;

- unsatisfactory efficiency, due to the fact that when injecting multiphase media, a screw working element mounted on the same shaft as the impeller at shallow depths of immersion of the pump, contributes to a more intense release of gas from the pumped medium, therefore, the flow is interrupted.

The closest in technical essence to the proposed one is a submersible monoblock multistage centrifugal pump RSG, the first stage on the suction side of which contains an impeller consisting of a drive and a driven disc with vanes located between them, a guiding apparatus with spiral vanes and a device that creates a backwater in the entrance area fluids into the impeller channel (FAIATEC catalog 1997, RSG submersible pump for liquefied gases).

The main disadvantages of the pump include:

- the need for increased back-up pressures, leading to significant material and energy costs, manifested through the use of additional sections (lengths) of the tubing and cable, as well as voltage losses in the additional cable section;

- the unsatisfactory performance of such a stage in the designs of oil pumps due to their small diametrical dimensions, since the back pressure created by the small axial wheel diameter is insufficient to achieve the continuity of the flow.

The objective of the invention is the creation of a centrifugal borehole pump stage, which provides an increased amount of backwater in the zone of fluid entry into the radial channels of the impeller, a decrease in the immersion depth of the pump at a dynamic level, and an increase in the efficiency of the pump.

This problem is solved by the proposed step of a centrifugal borehole pump, which includes an impeller consisting of a driving and driven disks with vanes located between them, a receiving and flow guide vanes with spiral vanes, and a device that creates a back up in the area of fluid inlet into the channel of the impeller.

What is new is that the backpressure device is made in the form of a multi-start (no more than three) screw, the sleeve base of which is provided with a shoulder rigidly connected to the flow guide device smoothly interfaced on the suction side with the cylindrical section of the sleeve base and forming an annular ring with the screw face shaped space, moreover, on the cylindrical section of the sleeve base, inclined thin-walled ribs are made having a winding direction opposite to the rotation of the impeller with an angle of elevation of the screw lines equal to 40 ... 45 °, and protruding beyond the sleeve base.

Figure 1 shows a device that creates a backwater in the area of fluid entry into the channels of the impeller.

Figure 2 - section of the pump in partial section.

Figure 3 is a view of the flow guide apparatus and the device that creates a backwater from the suction side.

The pump stage contains an impeller 1 (figure 2), consisting of a drive 2 and a driven 3 disks bearing bearing rings 4 and 5, radial blades 6, and a receiving 7 and discharge 8 guide vanes with their blades 9 and 10 (figure 2 and 3). The flow guide device 8 is equipped on the suction side with a device rigidly installed in it for creating a backwater 11 (Fig. 1), having a sleeve base 12, which at one end smoothly passes to a larger diameter along the radius, forming a shoulder 13.

The horizontal section of the sleeve base 12 is provided with thin-walled screw ribs 14 having a direction opposite to the rotation of the impeller 1 and inclination angles on the surface of the ribs equal to 40 ... 45 °. At the other end of the sleeve base 12, the screw ribs 14 extend beyond the sleeve base. The annular figure space "g" is located on the transitional section of the flow guide device 8. At angles of 40 ... 45 °, the speed of entry of the fluid flow into the channels of the impeller is optimal.

Each Central wall 15 of the screw ribs 14 is connected with its peripheral wall along a radius of 16 (figure 2).

The pump operates as follows. When the impellers 1 rotate (FIG. 2), the fluid from the cavities “a” is directed into the radial channels “b”, and then into the spiral channels “into” the receiving guide apparatus 7, from where it enters the channels “g” (FIG. 3) and further, into the channels “e” of the flow guide device 8. Here, the moving fluid still maintains the direction of movement in the direction of rotation of the impeller 1. Once in the ring-shaped space “g” (Fig. 1), the fluid flow smoothly changes its direction of motion, i.e. e. the liquid from this moment moves along the channels "and" towards the rotation of the worker eights Wheels 1 and at the outlet of the helical channels "and" meet its blades 6 of the impeller 1. As a result, the liquid flow runs into the blade 6 at a speed higher backwater forming in the entrance to the channels zone "b".

The proposed technical solution improves the efficiency of the pump due to the reduction of the number of stalls in the zone of fluid entry into the first stage, and the supply of devices subsequent to the first stage, creating a backwater, leads to the appearance of excess backwater in each stage. As a result, the optimal point of the H-Q graph moves to the right side from the origin, i.e. increased consumption and efficiency. The immersion depth of the pump under the dynamic level is also reduced.

Claims (1)

The stage of a centrifugal borehole pump, comprising an impeller consisting of a driving and driven disks with vanes located between them, a receiving and flow guide vanes with spiral vanes, and a device that creates a back up in the area of fluid inlet into the channel of the impeller, characterized in that the device that creates the support is made in the form of a multi-start screw, the sleeve base of which is provided with a shoulder rigidly connected to the flick guide device, smoothly conjugated from the suction side with a cylindrical m section of the sleeve base and forming a ring-shaped space with the end of the screw, moreover, inclined thin-walled ribs are made on the cylindrical section of the sleeve base, having a winding direction opposite to the rotation of the impeller with a helix angle of 40 ... 45 ° and protruding beyond the sleeve base .

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