RU2311561C1 - Design of multistage pump - Google Patents

Abstract

FIELD: oil and gas producing industry.

SUBSTANCE: invention relates to production of electric centrifugal pumping units for oil wells. Proposed multistage pump has housing, centrifugal impeller s, guide assemblies, shaft radial and axial bearings. Centrifugal impellers are provided with guide assemblies secured on wall and made of plates twisted to center along involute. Sealing rings arranged between centrifugal impellers are made in form of radial bearings engaging with housing. Axial and radial bearings between shaft and housing are installed at pump input and output. When radial bearings are arranged out of passage, area, they are not subjected to abrasive wear. Centrifugal impellers are not choked with abrasives as they have no pockets for accumulating abrasives. Deposition of salts on centrifugal impellers is reduced owing to straight-floe make of rotor.

EFFECT: increased wear resistance of pump.

2 dwg

Description

The invention relates to submersible multistage centrifugal pumps for oil production from wells and can be used in the new design of cost-effective wear-resistant pumps for low-flow wells instead of rocking machines.

Known devices of multi-stage pumps containing a set of stages assembled in a cylindrical housing and consisting of impellers and guide vanes having bores in the pins, serving as radial bearings for the pump rotor (patent RU 2249129 C2, 03/27/2005).

A disadvantage of the known pumps is their limited functionality.

A device is known for a multistage pump containing a housing, centrifugal wheels, guide vanes, a shaft, axial and radial bearings (patent RU 2250393 C2, 04/20/2005).

A disadvantage of the known multi-stage pump is its limited functionality, limited profitability due to accelerated abrasive wear of radial bearings.

The increased removal in mechanical aging of mechanical particles of both a natural nature and the rust formed on the inner surfaces of the casing leads to accelerated abrasive wear of the radial bearings of submersible installations of electric centrifugal pumps.

The wear process has an avalanche-like character. For a small part of the total operating time, the pump unit loses its flow rate so that further use of the unit becomes unprofitable, and it requires repair.

The objective of the invention is to ensure that the characteristics of the pumping units are maintained for a longer time under conditions of increased content of solids in the pumped liquid.

The technical result is achieved by the fact that in a multi-stage pump device comprising a housing, centrifugal wheels, guiding devices, a shaft, radial and axial bearings, according to the invention, the centrifugal wheels are provided with wall-mounted guiding devices made of plates twisted to the center by involute, additionally centrifugal the wheels are equipped with sealing rings located between them, made in the form of radial bearings interacting with the housing, axial and radial under ipniki between the shaft and the housing are mounted on the inlet and outlet of the pump.

In the proposed multistage pump device, the layout is improved, radial bearings are changed. As a result of the use of radial bearings between the housing and the rotor in the gaps in which there is no flow of abrasive fluid, wear resistance and durability are ensured.

Currently, there is no design, neither domestic nor foreign submersible centrifugal multistage pumps, in which the wear of radial bearings would not lead to a loss of shaft stability.

The proposed technical solution when used in production will increase the stability margin of the rotor and positively change the undesirable process of formation of standing waves on the shaft by increasing the rigidity of the rotor.

Figure 1 shows the device of a multi-stage pump, a General view of the inlet to the pump.

Figure 2 conditionally shows the basic set of elements of a multi-stage pump.

The multi-stage pump has a shaft 1, a key 2 on the shaft, a guiding apparatus 3, a polyurethane ring 4, a centrifugal wheel 5, a side wall of a centrifugal wheel 6, a pump casing 7, a grill 8, axial bearings 9, a cage 10 and a radial bearing sleeve 12, a nut 11, split snap ring 13.

The multi-stage pump is as follows. In the annular groove of the shaft, a split retaining ring 13 is installed, in the keyway - the shared key 2. The bronze sleeve 12 of the radial bearing 10 is installed all the way on the split retaining ring 13, and on the end of the sleeve - the grill 8. In the annular groove of the grill 8, a polyurethane ring is installed 4, which, with its rim, interacts with the groove of the centrifugal wheel 5 as a seal, and interacts with the housing 7 as a radial bearing on the outer surface. The guide apparatus 3 is installed in the centrifugal wheel 5, the ring is made of polyurethane 4, which interacts with the housing 7. The centrifugal wheel has a side wall 6 with the guide apparatus 3. The sequential arrangement of the centrifugal wheels 5 and the radial bearings 4 in the form of o-rings provides a tight inner passage for passage pumped liquid, eliminates the gap between the elements and the housing 7. A certain estimated number of elements in the set is completed with a grill 8. Then into the housing on both sides disks of axial bearings 9 are installed on the grilles 8, nuts 11 are mounted on the bearings 10 of the radial bearings, which seal the entire package of elements 3, 4, 5, 8, ensuring free sliding of the axial bearings 9. The shaft 1 of the multi-stage pump and the housing 7 are connected at the input to the shaft and the casing of the submersible motor, and the casing 7 at the outlet is connected to the tubing. The electric cable from the electric motor is laid along the tubing and fastened with clamps until it reaches the surface through the fountain fittings.

The proposed multistage pump device is a fixed housing 7, in which centrifugal wheels 5 and guide vanes 3 with radial bearings 4 are mounted with relative rotation.

The operation of a multi-stage pump is as follows. Before starting, a multistage pump in the well should be located below the dynamic fluid level. When the electric motor is turned on, centrifugal wheels give a flow of pumped liquid directed to the periphery. The radial movement of the liquid creates a vacuum in the central part of the impeller, as a result of which the liquid is sucked in.

The conversion of the kinetic energy transmitted by the impeller into the potential energy occurs in the guide apparatus of each stage, and the pressure of the pumped liquid increases due to centripetal forces.

In comparison with the well-known base object of the ESP, the proposed multistage pump device has expanded functionality due to simplification of the design, increased wear resistance, and improved profitability. The proposed design excludes radial bearings subject to abrasion. The centrifugal wheel is made of plastic, which allows the use of a simplified mold or stamp. The guide apparatus is made of a metal plate twisted to the center of the centrifugal wheel on an involute. The front end of the plate is fixed to the wall 6. The assembly of the pump elements is simplified. Increased wear resistance is achieved due to the formation of abrasive fluid flow inside the working elements and the elimination of fluid flow through the gaps in the radial bearings. The abrasive fluid does not penetrate into the gap between the housing and the working elements due to the flat axial plain bearings 9. The centrifugal wheels and guide vanes form a channel for the flow of the pumped abrasive fluid without pockets where solid particles could accumulate.

The working elements under the action of axial loads fit tightly against each other along the end planes and represent a rigid rotor on the shaft. This circumstance significantly changes the amplitude of standing waves on the shaft, reduces vibration loads on the electric motor and the installation as a whole. Simplification of the design of the working elements allows you to increase the profitability of the installation, reduce operating costs, improve maintainability, expand functionality.

In the well-known ESP in the oil well, free gas enters with the pumped liquid, which leads to a decrease in flow and pressure. With a high gas content, the ESP operation becomes unstable and leads to a disruption of the pump supply. The useful work of gas is not used when raising the reservoir fluid in the tubing, since for the most part the gas is directed by the separator into the annulus.

The proposed device multi-stage pump allows you to pump out a liquid with a high gas content due to the direct-flow channel without pockets in the working elements. With increased gas content of the reservoir fluid, a conical pump is used, which practically does not require additional capital costs and consists in the optimal layout of various types of centrifugal wheels. The flowing part of the elements of a multistage pump changes in accordance with a change in the parameters of the pumped gas-liquid medium. An optimal conical pump should include up to about three packages of different types of centrifugal wheels: a package of the highest capacity, then centrifugal wheels of intermediate and lower capacity move downstream.

The principle of the optimal arrangement of a conical pump from an available set of centrifugal wheels for a given well flow rate and gas content at the inlet can be based on minimizing the power consumed by the pump.

The proposed multi-stage pump device can be used in the new design of wear-resistant cost-effective pumps for low-rate oil wells instead of expensive rocking machines.

Using the installation in production will allow to obtain a positive technical and economic effect. The multistage pump device will find wide demand in the Russian market and abroad.

Claims (1)

A multi-stage pump device comprising a housing, centrifugal wheels, guide vanes, a shaft, radial and axial bearings, characterized in that the device has centrifugal wheels equipped with wall-mounted guide vanes made of plates twisted to the center along the involute, additionally centrifugal wheels are equipped with located between them sealing rings made in the form of radial bearings interacting with the housing, axial and radial bearings between the shaft and the housing It becomes the inlet and the outlet of the pump.

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