RU2234620C1 - Submersible multistage centrifugal pump - Google Patents

Abstract

FIELD: oil producing industry.

SUBSTANCE: invention relates to pumps designed for lifting liquids from wells. Proposed pump contains stages with guide vane assemblies in which main axial supports made of wear-resistant material with covers and impellers are mounted. Each impeller has its own axial support being a seal dividing suction and discharge spaces. Axial support is made in form of bead projecting on end face of impeller and resting on surface of cover. Shaft of pump is non-round in section and it carries hub of impeller fitted with clearance and separating washers made of antifriction material and provided with holes corresponding to non-found section of shaft. Hub of impeller is made projecting over end face of last impeller from side of inlet. Separating washers are installed on shaft for axial displacement at both sides from impeller hub. Thickness of each separating washer is less than axial clearance formed by end face of hub and end face of main axial support. Guide vane assembly with main axial support is installed before first impeller. End face of main axial support pointed to impeller side forms, together with separating washer, axial clearance whose size is less than height of bead of additional support of impeller.

EFFECT: increased service life of pump owing to prevention of destruction of first impeller.

1 dwg

Description

The invention relates to pump engineering, and more particularly to borehole pumps for lifting water and liquids from wells.

Known submersible multi-stage pump, the stage of which contains a centrifugal impeller, a guide apparatus and its cover (RU 2186251 C1, CL F 04 D 13/10, 07.27.2002). The disadvantages of such a pump include wheel basing in the pump guide, in which it is centered both on the pump shaft mounted in its radial bearings and in the radial bearings of the guide, resulting in increased friction due to manufacturing errors, and part power is spent on overcoming it. In addition, if solid particles get into the gaps, it is possible to jam and the pump is short-lived.

Closest to the invention is a multi-stage submersible pump containing stages with guide vanes, in which the main axial bearings of wear-resistant material are mounted, caps and impellers, each of which has its own additional axial bearing, which is also a seal separating the suction and discharge cavities, and made in the form of a shoulder acting on the end of the impeller, resting on the surface of the lid; non-circular section shaft, on which an impeller hub is installed with a clearance, the hole of which corresponds to a non-circular section of the shaft, and spacer washers of antifriction material (EP 0554803 A1, CL F 04 D 29/16, 13/10, 11.08.1993) .

The disadvantages of this pump design include a quick failure and destruction of the first impeller (directly sucking fluid from the well) and pressure loss due to the lack of a main support of wear-resistant material in front of the first impeller.

The objective of the present invention is to increase the durability of the pump while maintaining the initial pressure value by preventing the destruction of the first impeller.

The technical result is achieved in that in a multi-stage submersible pump containing steps with guide vanes, in which the main axial bearings of wear-resistant material are mounted, covers and impellers, each of which has its own additional axial support, which is also a seal separating the suction and discharge cavities , and made in the form of a shoulder acting on the end of the impeller, resting on the surface of the lid; a non-circular sectional shaft, on which an impeller hub is installed at a clearance with a gap, a bore of which corresponds to a non-circular section of the shaft, and spacer washers of antifriction material, according to the invention, the impeller hub is protruding above the end face of the latter from the input side, spacer washers are mounted on the shaft with the possibility of axial movement on both sides of the impeller hub, each of the washers has an opening corresponding to a non-circular section of the shaft, and a thickness smaller than the axial a gap formed by the end face of the hub and the end of the main support, in front of the first impeller, a guide apparatus with a main axial support is installed, the end of which facing the impeller forms an axial clearance with a spacer that is smaller than the height of the shoulder of the additional support of the impeller.

Due to the installation of the guide apparatus in front of the first impeller, the destruction of the end surface of the impeller from the suction side is prevented due to the prevention of the contact of its end with the surface of the lid as the shoulder of the axial additional support wears out, the friction surfaces come closer and the contact along the main axial support. The consequence of this is that the pressure provided by the first impeller is maintained throughout the life of the pump.

The invention is illustrated in the drawing, which shows the best embodiment of the first stage of a submersible multistage pump.

The first stage of a multi-stage submersible pump consists of an impeller 1, two guide vanes 2 and 3 with the main axial bearings 4 and 5 of wear-resistant material, such as ceramic, a cover 6 with an auxiliary axial support 7, washers 8 and 9 made of antifriction material, for example, filled with graphite or fluoropolymer molybdenum disulfide and shaft 10. At the end of the impeller 1, an annular collar 11 is made on the suction side, resting on the surface of the support 7 of the cover 6, separating the suction and discharge cavities as a seal, as well as being an additional axial support of the impeller 1. The shaft 10 is made of non-circular section, the mounting holes of the impeller 1 and spacer washers 8, 9 correspond to the non-circular section of the shaft 10 and allow their axial movement. The thickness of the washers 8, 9 is less than the axial clearance formed by the end face of the impeller hub 1 and the end face of the corresponding main axial support 4 or 5. The guide apparatus 2 is installed in front of the impeller 1 and has a main axial support 4, the end of which facing the wheel 1 forms with washer 8 axial clearance k1. The size of the specified gap k1 is less than the height k2 of the shoulder 11 of the additional impeller support.

The device operates as follows.

The impeller 1, driven by rotation of the shaft 10, carries out the pumping of the liquid, as a centrifugal. In the absence of pressure at the outlet, the impeller, carried away by the flow, is pressed with its end through the washer 9 to the main support 5 mounted in the guide apparatus 3. If there is pressure at the pump outlet, the impeller is pressed against the pressure drop in the suction and discharge cavities the auxiliary support 7 of the cover 6 by means of a collar 11. As the collar 11 is worn, which also serves as a seal separating the suction and discharge cavities to create a pressure differential, the ends of the working hub come closer together wheel 1 and the main gear 4 - without breaking the seal, i.e., without reducing the volumetric efficiency of the pump. After the collar 11 is worn by the clearance k1, the end of the impeller 1 is pressed through the washer 8 to the main support 4 mounted in the guide apparatus 2. After this, the wear rate of the collar 11 is reduced by several orders of magnitude, because the peripheral friction velocities sharply decrease due to the transition of the contact to a smaller diameter, and the wear rate of the additional and main bearings becomes equal, which is a condition for the seal not to break. To prevent contact of the end face of the impeller 1 with the cover 6, the height k2 of the shoulder 11 is greater than the gap k1.

Since the shaft 10 transmits “pure” torque to the wheel 1, without obstructing its axial and angular movements in the longitudinal planes, due to the coupling of the impeller 1 with the shaft 10 with a clearance, jamming of the wheel when solid particles enter the gap is prevented, and the shaft manufacturing accuracy , its supports, the actual wheel and the guide device may be less high than its counterpart.

Due to the installation of an additional guide vane at the pump inlet and the installation of the main impeller support in it, the durability of the first impeller with a given head is increased to the durability of all pump wheels. In addition, installing a guide vane at the pump inlet reduces hydrodynamic losses from fluid flow instability.

Claims (1)

A multi-stage submersible pump containing stages with guiding devices, in which the main axial bearings of wear-resistant material are mounted, covers and impellers, each of which has its own additional axial support, which is also a seal separating the suction and discharge cavities, and made in the form of a protruding the end of the impeller shoulder, resting on the surface of the cover; a shaft of non-circular section, on which the impeller hub is installed at a clearance with a gap, the bore of which corresponds to a non-circular section of the shaft, and spacer washers of antifriction material, characterized in that the impeller hub is protruding above the end of the latter from the input side, the spacer washers are mounted on the shaft with the possibility of axial movement on both sides of the impeller hub, each of the washers has an opening corresponding to a non-circular section of the shaft, and a thickness smaller than the axial a gap formed by the end face of the hub and the end of the main support, in front of the first impeller, a guide apparatus with a main axial support is installed, the end of which facing the impeller forms an axial clearance with a spacer that is smaller than the height of the shoulder of the additional impeller support.