CN109209897A

CN109209897A - Multistage centrifugal pump rotor axial force balance mechanism

Info

Publication number: CN109209897A
Application number: CN201811311051.0A
Authority: CN
Inventors: 叶晓琰; 胡敬宁
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2018-11-06
Filing date: 2018-11-06
Publication date: 2019-01-15
Anticipated expiration: 2038-11-06
Also published as: CN109209897B

Abstract

The purpose of the present invention is to provide a multi-stage centrifugal pump rotor axial force balance mechanism that can reduce energy loss and has a simple structure, including the first-stage impeller of the centrifugal pump and the inlet section of the centrifugal pump, and the front cover plate of the first-stage impeller and the inlet section. A first radial gap C1, a first axial gap C2 and a second axial gap C3 are arranged in sequence between them. The liquid outlet of the first radial gap C1 is communicated with the inlet of the centrifugal pump, and the second axial gap C3 It is connected with the liquid outlet of the first-stage impeller, and the inlet section is provided with a high-pressure liquid flow introduction channel. hole. Due to the introduction of high-pressure liquid flow, an axial force from the front end to the rear end will be generated. This axial force is balanced with the axial force from the rear end to the front end generated by the impeller under the influence of hydraulic force, which is the same as the axial force of the traditional multistage pump. Compared with the balance mechanism, the structure is simplified, the recovery of part of the balance liquid flow is realized, and the leakage loss is reduced.

Description

Multistage centrifugal pump rotor axial force balance mechanism

Technical field

The invention belongs to Centrifugal Pump Design manufacturing fields, and in particular to a kind of Multistage centrifugal pump rotor axial force balance machine Structure.

Background technique

When being centrifuged pump operation, be rotated in generation water pressure, objective due to suction eye at forward and backward cover board of impeller are deposited So that back shroud of impeller is greater than the active area of front shroud by the active area of waterpower, so acting on forward and backward cover board Power cannot mutually balance each other, therefore the power of an axial direction can be generated, the direction of this axial force is the back shroud by impeller always It is directed toward front shroud.For being collectively aligned the multistage segmental centrifugal pump of impeller, each impeller generates that size is essentially identical, direction Consistent axial force, the resultant force of these axial forces be very it is big (such as in desalination plant, production water scale be 5000m3/d~ The axial force that the multistage centrifugal centrifugal pump impeller of 20000m3/d generates is about 40kN~100kN).So in centrifugal multistage pump multiple centrifugal pump There must be axial force balance mechanism, balance mechanism generates a reversed axial force to balance the axial force of impeller generation.

Traditional axial force balancing method is that the axial force in such a way that balancing frame adds balancing drum to balance impeller (also has It is individually balanced using balancing frame, is the special case that balancing drum does not generate equilibrant force).The course of work of balancing device is exactly Liquid stream with high pressure energy is reduced to the process of the liquid stream of low pressure energy, but this process will lead to the loss of energy, this energy Amount loss is exactly to pump volumetric loss described in industry.

Summary of the invention

Energy loss can be reduced the object of the present invention is to provide one kind and the simple Multistage centrifugal pump rotor of structure is axial Dynamic balance mechanism.

To achieve the goals above, a kind of the technical solution adopted by the present invention are as follows: Multistage centrifugal pump rotor axial force balance Mechanism, the inducer of first stage impeller and centrifugal pump including centrifugal pump are provided between the front shroud and inducer of first stage impeller The first radial clearance C1, first axis clearance C 2 and the second the axial gap C3's, the first radial clearance C1 being sequentially communicated goes out liquid The inlet communication of mouth and centrifugal pump, the liquid outlet of the second axial gap C3 are connected to the liquid outlet of first stage impeller, inducer setting There is high pressure liquid stream introduction passage, high pressure liquid stream, which introduces introduction passage from the back shroud of centrifugal pump impeller and constitutes reflux, leads to Road is provided with throttle orifice in introduction passage.

In above scheme, since the introducing of high pressure liquid stream can generate an axial force by front end rear end, this axial direction Power and impeller influenced by waterpower the axial force balance by rear end forward end generated, this structure and traditional multiple stage pump shaft to Dynamic balance mechanism is compared, and structure is simplified, and realizes the recycling of partial equilibrium liquid stream, reduces leakage loss.

Detailed description of the invention

Fig. 1 is overall structure diagram of the invention；

Fig. 2 is enlarged schematic partial view in Fig. 1.

Specific embodiment

As shown in Figure 1 and Figure 2, a kind of Multistage centrifugal pump rotor axial force balance mechanism, the first stage impeller 10 including centrifugal pump With the inducer 20 of centrifugal pump, it is provided between the first radial direction being sequentially communicated between the front shroud and inducer 20 of first stage impeller 10 Gap C1, first axis clearance C 2 and the second axial gap C3, the liquid outlet of the first radial clearance C1 and the inlet communication of centrifugal pump, The liquid outlet of second axial gap C3 is connected to the liquid outlet of first stage impeller 10, and inducer 20 is provided with high pressure liquid stream introduction passage 22, high pressure liquid stream, which introduces introduction passage 22 from (not shown) at the back shroud of centrifugal pump impeller and constitutes reflux, leads to Road is provided with throttle orifice 21 in introduction passage 22.

Centrifugal pump inlet flow direction shown in FIG. 1 is right-to-left, due to the left side back shroud of centrifugal pump impellers at different levels Compression area is bigger than right side front shroud, can generate the unbalanced axial force of waterpower on impeller when being centrifuged pump operation, direction is to the right.It is false If the resultant force for the axial force that impellers at different levels generate is F1, i.e., the active force to the right that entire rotor is subject to is F1.The present invention be by Stressed member of the front shroud of the first stage impeller 10 of centrifugal pump as equilibrant force, high pressure liquid stream from high pressure liquid stream introduction passage 22 into Enter, entire balance mechanism generates a biggish equilibrant force to the left, it is assumed that this active force is F2.Centrifugal pump operates normally When, F2 should be equal to F1, just can guarantee 30 axial force balance of rotor；Since Working Conditions of Centrifugal Injection Pumps often changes, F2, F1 are sent out Changing, at this point, rotor is moved to the left, in the process first axis clearance C 2 and the second axial gap C3 if F2 is greater than F1 Become larger, the first radial clearance C1 it is constant, the high pressure liquid stream flow of introducing increases, due to being provided with throttling in introduction passage 22 Hole 21, so that the pressure difference between the forward and backward cover board of first stage impeller 10 reduces, F2 also reduces therewith；When F2 is less than F1, rotor is to the right It is mobile, in the process first axis clearance C 2 and the second axial gap C3 gradually become smaller, the first radial clearance C1 it is constant, introduce High pressure liquid stream flow reduce, due to being provided with throttle orifice 21 in introduction passage 22, so that between the forward and backward cover board of first stage impeller 10 Pressure difference become larger, F2 is also increased with it；And so on, axial force suffered by centrifugal pump rotor just reaches dynamic equilibrium, thus real Show centrifugal pump rotor to operate near some equilbrium position.In above process, pass through first axis clearance C 2 and first The balancing device liquid stream of radial clearance C1 therefore can reduce the leakage rate of centrifugal pump instead of the leakage of first stage impeller；Pass through The balancing device liquid stream of second axial gap C3 enters first stage impeller outlet mainstream, realizes the recycling of partially liq energy.

Preferably, be provided on the inner wall of inducer 20 with 30 coaxial inner conductor of rotor arrangement sleeve 40, sleeve 40 it is interior The first radial clearance C1, the end of sleeve 40 are constituted between the choma 11 being arranged on the front shroud of wall and first stage impeller 10 The first axis clearance C 2, inducer are constituted between the inner gimbal ring 12 being arranged on the front shroud of face and first stage impeller 10 The second axial gap C3 is constituted between the outer gimbal ring 13 being arranged on 20 end face and the front shroud of first stage impeller 10.

Further, the chamber between the first and second axial gap C2, C3 constitutes chamber A, the throttling being arranged on inducer 20 21 connecting chamber A of hole and high pressure liquid stream introduction passage 22.

The high pressure liquid stream total flow Q of introducing is divided into two-way: liquid stream (flow Q1) is along the second variable axial gap C3 all the way Into the exit of first stage impeller 10, converged with the outlet mainstream of the first stage impeller of pump；Another way liquid stream (flow Q2) is along variable First axis clearance C 2 and the first constant radial clearance C1 enter pump inlet, with pump water inlet mainstream converge.Due to chopped-off head leaf The active area that 10 back shrouds are greater than front shroud by the active area of waterpower is taken turns, so centrifugal pump can produce on impeller at runtime The unbalanced axial force of unboiled water power, from the front to the back, i.e., entire rotor is generated displacement backward by active force backward in direction, So that first axis clearance C 2 and the second axial gap C3 become larger, the flow Q1 of first stage impeller is entered by the second axial gap C3 It significantly increases, although first axis clearance C 2 increases, since the first radial clearance C1 is fixed and invariable, plays throttling always Effect, so the increase of Q2 is limited；Dramatically increasing for Q1 and being increased slightly for Q2, so that liquid stream total flow Q is dramatically increased, At this moment due to being provided with throttle orifice 21 in inducer liquid stream introduction passage 22, so that the pressure P1's of chamber A is greatly lowered, Equilibrant force also greatly reduces therewith, and rotor will move forward.In this way, rotor 30 certainly exists some equilbrium position, impeller The axial force of generation is equal with equilibrant force, to realize the autobalance of axial force.

The present invention has fully phased out traditional balancing frame, balancing drum, enormously simplifies in structure；Part liquid stream passes through second Axial gap C3 enters the exit of first stage impeller 10, forms the flow of centrifugal pump, realizes partial equilibrium leakage liquid stream Energy regenerating；Partial discharge enters the suction inlet of centrifugal pump, this portion by the first radial clearance C1, first axis clearance C 2 Liquid separation stream improves the volumetric efficiency of first stage impeller 10, reduces energy instead of the leakage flow at conventional impellers choma Loss, the fully effective leakage rate that traditional structure axial thrust balancing devices are utilized.

Claims

1. a multistage centrifugal pump rotor axial force balance mechanism, is characterized in that: comprise the first stage impeller (10) of centrifugal pump and the inlet section (20) of centrifugal pump, the front cover plate of first stage impeller (10) and The inlet section (20) is provided with a first radial gap C1, a first axial gap C2 and a second axial gap C3 which are communicated in sequence, and the liquid outlet of the first radial gap C1 is communicated with the inlet of the centrifugal pump, The liquid outlet of the second axial gap C3 is communicated with the liquid outlet of the first-stage impeller (10), and the inlet section (20) is provided with a high-pressure liquid flow introduction channel (22), and the high-pressure liquid flow flows from the back of the final stage impeller of the centrifugal pump. An introduction channel (22) is introduced at the cover plate to form a return passage, and an orifice (21) is arranged in the introduction channel (22).

2. The multistage centrifugal pump rotor axial force balancing mechanism according to claim 1, characterized in that: the inner wall of the inlet section (20) is provided with a sleeve (40) coaxially arranged with the rotor (30) , the first radial gap C1 is formed between the inner wall of the sleeve (40) and the mouth ring (11) provided on the front cover of the first-stage impeller (10). The first axial gap C2 is formed between the inner balance rings (12) provided on the front cover plate of the stage impeller (10), and the end face of the inlet section (20) and the front cover plate of the first stage impeller (10) The above-mentioned second axial gap C3 is formed between the outer balance rings (13) provided above.

3. The multistage centrifugal pump rotor axial force balance mechanism according to claim 1, characterized in that: the chamber between the first and second axial gaps C2, C3 constitutes chamber A, and the upper part of the inlet section (20) The provided orifice (21) communicates the chamber A with the high-pressure liquid flow introduction channel (22).