UA55930A - Centrifugal multi-step pump - Google Patents

Abstract

Centrifugal multi-step pump has fixed guide blade grid, working wheel, where between main and covering disc there is fixed working blade grid. Fixed guide blade grid is made as radial plates and is installed at the section in the front cavity of the working wheel with a gap with respect to the covering disc. At the main disc there are fixed impellers, with a gap with respect to the inner wall of the guide apparatus; at that at the end surfaces of the working wheel there are provided grooves, where there are placed support rings; besides that, the bushing of the guide apparatus has a support ring.

Description

The invention relates to pump construction, namely to centrifugal multi-stage pumps, and can be used in systems of artificial reservoir pressure support (PSG) at oil fields in the oil, oil and gas, mining and other industries, as well as as a source of hydraulic energy for the drive of hydraulically driven turbopump units , in particular, for lifting reservoir fluids and gas-liquid mixtures with high gas content from wells.

A known centrifugal multistage pump containing a housing in which a fixed guide vane grid is installed on the side of the main disk of the impeller. The impeller is installed in the housing and has at least two rows of working blade grates between the main and cover disk. (akhs. USSR Mo 684158, publ. 05.09.79. bul. Mo 33).

This analog is the closest in technical essence to the proposed invention and is accepted as a prototype.

The disadvantage of the known design is the low efficiency caused by the inclusion of a fixed guide vane grid in the flow part, which leads to additional vortex formation in the channel of the impeller.

The basis of the proposed invention is the task of creating a centrifugal multi-stage pump, in which, by reducing the axial force acting on the impeller, while simultaneously improving the dynamic characteristics of the front seals, it is possible to install a large number of reliably working stages with high efficiency on one pump shaft.

The task is solved in this invention, which, like the known centrifugal multistage pump, has a guide vane grid, a working wheel, in which a working vane grid is fixed between the main and covering disks, according to the invention, a fixed guide vane grid is made in the form of radial plates and installed on the section in the front sinus of the impeller with a gap relative to the covering disc, and on the main disc fixed impellers with a gap relative to the inner wall of the guide apparatus, while on the end surfaces of the impeller, grooves are made in which the thrust rings are placed, in addition, the sleeve of the guide apparatus also has a thrust ring.

The density of the stationary guide blade grid can have the following dependence ss where I is the length of the blade;

Isr is a step on the average diameter of a fixed blade lattice.

The gap between the blades of the fixed guide grid and the covering disc can be equal to

With - (0.01 - 0.0055)0, where

C - gap; p - outer diameter of the impeller.

The gap between the ends of the impellers and the inner wall of the guide apparatus can be equal to

Z - (0.0017 -- 0.0055) 0, where 5 is the gap; p - outer diameter of the impeller.

Installation of a fixed guide grid on the section in the front sinus of the impeller and its implementation in the form of radial plates helps to reduce the speed of rotation of the pumped liquid in the sinus of the impeller and increase the pressure of the liquid on the covering disk of the impeller. Placing the impellers on the main disk of the impeller will increase the speed of rotation of the liquid in the rear sinus, thereby reducing the pressure and, thus, the axial force on the main disk.

Thanks to this, it is possible to achieve a zero value of the axial force acting on the impeller and, in addition, to ensure a fluid mode of friction in the sliding supports formed by the thrust rings on the end surfaces of the impeller and on the sleeve of the guide apparatus.

In the proposed design, the axial force acting on the impeller is perceived by the end thrust rings, which in this case work as sliding supports, the lubricant for which is the pumped medium. Such a design of the front sinus, along with unloading the axial force, increases the bearing capacity of the front seals, which makes it possible to install a large number of stages on one pump shaft.

The use of a set of all significant features, including excellent ones, allows to increase the efficiency of the pump, increase the reliability and durability of the pump equipment and thus ensure the wide use of centrifugal multistage pumps in the oil and oil and gas industry.

Fig. 1 schematically shows the pump installation.

Fig. 2 shows a section of the flow part of the pump along A-A.

The pump unit has a block structure and contains an electric motor 1, connected to the input block 2 of the pump by means of a connecting coupling C and a bracket 4. The intermediate block 5 is connected to the input block 2 and the output block 6 by detachable connections. The outlet 7 is also attached to the output unit 6 with a detachable connection. Between the units 2, 5 and 6, supports 8 are installed, connected to the frame 9. Each pump unit contains a device placed between the sections 10 (Fig. 2) and the guide devices 11 (fig. 2) working wheels 12 (fig. 2), in the front sinuses of which radial blades 14 are installed on sections 10 with gaps 13 relative to the covering discs of the working wheels 12.

Impellers 16 are installed on the main disk of the impeller 12 with a gap 15 relative to the inner surface of the guide apparatus 11. Thrust rings 17 and 18 are placed in the annular grooves on the front and rear end surfaces of the impeller 12. The guide apparatus 11 has a sleeve 19, in the annular groove of which also thrust ring 20 is installed.

The pump works as follows:

The working wheels 12 of the pump are set in motion by the electric motor 1, which transmits the torque, through the coupling 3. The pumped medium enters the inlet pipe of the input unit 2, and is directed to the working wheel 12 of the first stage. After acquiring pressure in the impeller 12, the liquid enters the guide apparatus 11 and further into the impeller 12 of the next stage. After acquiring the required pressure in the steps of the input 2, intermediate 5, and output 6 blocks, the liquid from the last step exits through the tap 7 of the pump. Under the action of the system of fixed vanes 14 during operation, the flow in the front sinus is inhibited and the pressure of the fluid increases in it, which leads to an increase in the axial force acting on the covering disc.

Unloading of the impeller 12 from the residual axial force occurs due to the installation on the main disk of a system of radial impellers 16 with a gap 15, which spin up the flow and reduce the pressure in the rear sinus, which leads to a decrease in the axial force acting on the main disk.

At operating modes of the pump that differ from the optimal, the unbalanced axial force is perceived by the sliding supports 17, 18, 20, the bushing 19. The necessary indicators of the reliability of the sliding supports are achieved by reducing the axial force using a system of blades 14 and impellers 16 installed with gaps 13 and 15 respectively. The operation of the wheel 12 on the thrust rings 17 and 18 is ensured by the floating (not fixed to the shaft in the axial direction) execution.

Due to the impeller floating in the axial direction, the pump does not provide for the installation of unloading devices, which are used in traditional multistage centrifugal pumps.

The improvement of the dynamic characteristics of the front seals of the impellers 12 occurs due to the reduction of the swirl of the flow at the entrance to the seal and the increase of the pressure drop across it, as a result of which the bearing capacity of the front seals increases. Thus, an individual support bearing is installed on each stage of the pump, so the installation of intermediate bearing supports is not provided for in the pump.

The use of the proposed design of the pump provides the following advantages in comparison with the existing ones: the pressure capacity and efficiency of the pump increases; the reliability and durability of pumping equipment increases; the possibility of wide use in the oil, oil and gas and mining industries with high TEP is ensured. 9 | 3 4 2 5 ; 5 7

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Claims (4)

1. Centrifugal multi-stage pump, which has a fixed guide vane grid, an impeller, in which a work vane grid is fixed between the main and cover disks, which is characterized by the fact that the fixed guide vane grid is made in the form of radial plates and is installed on a section in the front sinus of the working wheels with a gap relative to the cover disk, and impellers with a gap relative to the inner wall of the guide apparatus are fixed on the main disk, while the end surfaces of the impeller have grooves in which thrust rings are placed, in addition, the sleeve of the guide apparatus has a thrust ring. 2, Centrifugal multi-stage pump according to claim 1, which is characterized by the fact that the density of the stationary guide pirpater grid has the following dependence - ? And where: - blade length; Ishio is a step on the average diameter of the blade grille. 3. Centrifugal multistage pump according to claims 1, 2, which differs in that the gap between the blades of the guide grid and the cover disk is equal to: З - (0.01 7 0.0055) 0, where: З - gap; p - outer diameter of the impeller. 4. Centrifugal multistage pump according to claims 1, 2, 3, which differs in that the gap between the ends of the impellers and the inner wall of the guide apparatus is equal to: З -(0.0017 7 0.0055) 0, where: З - gap; p - outer diameter of the impeller.