CN216278636U

CN216278636U - Balance drum sealing structure of water feeding pump

Info

Publication number: CN216278636U
Application number: CN202121811965.0U
Authority: CN
Inventors: 高华峰; 谢宗伟; 胡小林
Original assignee: SEPCO Electric Power Construction Co Ltd
Current assignee: SEPCO Electric Power Construction Co Ltd
Priority date: 2021-08-04
Filing date: 2021-08-04
Publication date: 2022-04-12
Anticipated expiration: 2031-08-04

Abstract

A sealing structure of a balance drum of a feed pump belongs to the sealing field of large-scale multistage centrifugal pumps and aims to improve the pump efficiency. The balance drum comprises a balance drum and a balance sleeve, wherein the balance sleeve is sleeved on the periphery of the balance drum, and a drum sleeve gap is formed between the outer wall of the balance drum and the inner wall of the balance sleeve; along the axial direction of the balance drum, the drum sleeve gap comprises 2N gap sections; in two adjacent gap sections, the gap size of one gap section is the theoretical minimum gap, and the gap size of the other gap section is smaller than the theoretical minimum gap. The drum sleeve gap between the balance drum and the balance sleeve is divided into 2N gap sections, and the gap size of one gap section is the theoretical minimum gap, and the gap size of the other gap section is smaller than the theoretical minimum gap. Therefore, under the condition that the actual absolute clearance meets the specified requirement, the leakage quantity of liquid passing through the clearance of the drum sleeve is reduced, the efficiency of the pump is improved by 1.4-2.5%, and the abrasion is not aggravated.

Description

Balance drum sealing structure of water feeding pump

Technical Field

The utility model belongs to the field of sealing of large-scale multistage centrifugal pumps, and particularly relates to a sealing structure of a balance drum of a water supply pump.

Background

The multistage centrifugal pump is generally applied to large-scale power stations, energy sources, chemical engineering and other projects, and taking the power stations as an example, the electric boiler feed water pump is relatively mature in application. The balance drum is generally arranged behind a last-stage blade, a balance chamber behind the balance drum is communicated with an inlet pipeline through a through-flow gap, the pressure in the balance chamber is the sum of the indoor liquid pressure and the through-flow pressure loss, axial thrust pointing to the inlet direction is generated due to the reaction force of liquid on an impeller in the operation process of the pump, and the axial thrust is balanced and offset by the pressure difference of two sides of the balance drum. In order to reduce the leakage of liquid from the high pressure zone in front of the balancing drum to the balancing chamber, it is better that the gap between the balancing drum and the balancing sleeve is small, but too small results in increased wear, difficulty in maintaining the gap and fragile components. There is a hard regulation on this gap in each relevant standard, such as the international universal pump standard API610, which explicitly requires the balance drum gap to be at least 0.021 inches (0.53 mm). When the design requirement of the balance drum gap is 0.53mm, the thermal efficiency of the pump is between 80 and 81 percent.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a sealing structure of a balance drum of a water feeding pump, which improves the pump efficiency.

The technical scheme adopted by the utility model is as follows: the water feed pump balance drum sealing structure comprises a balance drum and a balance sleeve, wherein the balance sleeve is sleeved on the periphery of the balance drum, and a drum sleeve gap is formed between the outer wall of the balance drum and the inner wall of the balance sleeve; the drum sleeve gap comprises 2N gap sections along the axial direction of the balance drum; in two adjacent gap sections, the gap size of one gap section is the theoretical minimum gap, and the gap size of the other gap section is smaller than the theoretical minimum gap.

Further, along the axial direction of the balance sleeve, the inner wall of the balance sleeve is a cylindrical surface with the same diameter;

the outer wall of balance drum is divided into 2N outer wall sections, and two adjacent outer wall sections are distributed along the radial dislocation of balance sleeve, and are coaxial and equal in diameter with two adjacent outer wall sections of each outer wall section.

Further, the outer wall of the balance drum is equally divided into 2N outer wall sections.

Further, N is 2.

Furthermore, one end of the balance drum is an inlet end adjacent to the tail end of the water feeding pump blade, and the other end of the balance drum is an outlet end; the orthographic projection of the gap section at the inlet end of the balance drum along the axial direction of the balance drum is positioned outside the orthographic projection of the gap section at the outlet end along the axial direction of the balance drum.

The utility model has the beneficial effects that: the utility model discloses a sealing structure of a balance drum of a feed pump, wherein a drum sleeve gap between the balance drum and a balance sleeve is divided into 2N gap sections, and in two adjacent gap sections, the gap size of one gap section is a theoretical minimum gap, and the gap size of the other gap section is smaller than the theoretical minimum gap. Therefore, under the condition that the actual absolute clearance meets the specified requirement, the leakage amount of liquid passing through the clearance of the drum sleeve is reduced, the efficiency of the pump is improved by 1.4-2.5%, and the abrasion of the balance drum and the balance sleeve is not aggravated.

Drawings

FIG. 1 is a schematic view of the present invention;

fig. 2 is a schematic view of the outer wall of the balancing drum.

In the figure, a balance sleeve 1, a balance drum 2, an outer wall section 2A, a drum sleeve gap 3 and a gap section 3A.

Detailed Description

The utility model is further described below with reference to the following figures and examples:

a water feed pump balance drum sealing structure is shown in figure 1 and comprises a balance drum 2 and a balance sleeve 1, wherein the balance sleeve 1 is sleeved on the periphery of the balance drum 2, and a drum sleeve gap 3 is formed between the outer wall of the balance drum 2 and the inner wall of the balance sleeve 1; the drum jacket gap 3 includes 2N gap segments 3A in the axial direction of the balance drum 2; in two adjacent gap segments 3A, the gap size of one gap segment 3A is the theoretical minimum gap, and the gap size of the other gap segment 3A is smaller than the theoretical minimum gap.

The utility model discloses a balance drum sealing structure of a water feeding pump, which divides a drum sleeve gap 3 into 2N gap sections 3A, wherein in two adjacent gap sections 3A, the gap size of one gap section 3A is a theoretical minimum gap, and the gap size of the other gap section 3A is smaller than the theoretical minimum gap, so that the gap section 3A equal to the theoretical minimum gap and the gap section 3A smaller than the theoretical minimum gap are arranged at intervals to form a labyrinth concave-convex gap, and the actual absolute gap still meets the condition that the actual absolute gap is not smaller than the theoretical minimum gap, and the gap section 3A smaller than the theoretical minimum gap is arranged, thereby reducing the leakage amount of liquid passing through the drum sleeve gap 3 and improving the efficiency of the pump.

Wherein N is a positive integer greater than 1, which facilitates dynamic balance adjustment. The theoretical minimum clearance is the minimum value explicitly required for the balance drum clearance in the international universal pump standard API 610.

The inner wall of the balance sleeve 1 can be concave-convex, the outer wall of the balance drum 2 is a column with equal diameter, and for convenience of manufacture, it is preferable that the inner wall of the balance sleeve 1 is a cylindrical surface with equal diameter along the axial direction of the balance sleeve 1 as shown in fig. 2; the outer wall of the balance drum 2 is divided into 2N outer wall sections 2A, two adjacent outer wall sections 2A are distributed along the balance sleeve 1 in a radial staggered mode, and the two outer wall sections 2A adjacent to the outer wall sections 2A are coaxial and have the same diameter.

The gap between the respective outer wall section 2A and the corresponding point of the inner wall of the balancing sleeve 1 forms a corresponding gap section 3A.

To further facilitate the machining, it is preferred that the outer wall of the balancing drum 2 is divided into 2N outer wall sections 2A.

N may be equal to 2, 3, 4, etc., and in order to facilitate dynamic balance adjustment and also facilitate manufacturing, in the present invention, N is 2, that is, there are 4 outer wall sections 2A of the balance drum 2. There are 4 gap segments 3A.

Because friction is more likely to occur at the inlet of the pump, one end of the balance drum 2 is an inlet end adjacent to the tail end of the water supply pump blade, and the other end of the balance drum is an outlet end; the orthographic projection of the gap section 3A at the inlet end of the balance drum 2 along the axial direction of the balance drum 2 is positioned outside the orthographic projection of the gap section 3A at the outlet end along the axial direction of the balance drum 2. Namely, the gap size of the gap section 3A at the inlet end of the balance drum 2 is larger than that of the gap section 3A at the outlet end, thereby effectively reducing the abrasion of the balance drum 2.

Taking a certain water supply pump as an example, the main parameter data of the water supply pump are as follows:

rated rotation speed: 3582 RPM;

motor nameplate power: 4150 KW;

lift: 2029m at minimum flow; 1757m at normal flow; 1666m under 100% working condition; the closing point HP is 2082m, and the closing point IP is 887 m; the performance curve ends HP and IP are 1348m and 582m respectively; maximum impeller diameter 1793 m;

flow rate: the performance curve ends HP and IP are 888m3/h and 962m3/h respectively; the rated performance ensures that the HP and the IP are 721.6m3/h and 80.8m3/h respectively under the working condition;

efficiency: maximum impeller diameter 82.4%;

pressure: the outlet HP is 156bar under the rated maximum flow condition, and the IP is 70.9 bar.

The international universal pump standard API610 specifically requires that the minimum balance drum clearance be no less than 0.021 inches, i.e., 0.53 millimeters, i.e., the theoretical minimum clearance is 0.53 mm. The drum sleeve gap 3 of the balance drum 2 of the water supply pump is divided into 4 sections, and the size of each gap section 3A is 0.53mm, 0.41mm, 0.53mm and 0.41mm from the inlet end to the outlet end in sequence. Experiments prove that the efficiency of the water feeding pump of the specification can reach 82.4%, and the thermal efficiency of the water feeding pump can reach 83.8% approximately. And the feed pump is disassembled after the experiment, and no scratch or scratch is found in the disassembling inspection.

Claims

1. The water feed pump balance drum sealing structure comprises a balance drum (2) and a balance drum sleeve (1), wherein the balance drum sleeve (1) is sleeved on the periphery of the balance drum (2), and a drum sleeve gap (3) is formed between the outer wall of the balance drum (2) and the inner wall of the balance drum sleeve (1); the method is characterized in that: the drum sleeve gap (3) comprises 2N gap sections (3A) along the axial direction of the balance drum (2); in two adjacent gap sections (3A), the gap size of one gap section (3A) is the theoretical minimum gap, and the gap size of the other gap section (3A) is smaller than the theoretical minimum gap; n is 2; one end of the balance drum (2) is an inlet end adjacent to the tail end of the water feeding pump blade along the axial direction, and the other end of the balance drum is an outlet end; the orthographic projection of the gap section (3A) at the inlet end of the balance drum (2) along the axial direction of the balance drum (2) is positioned outside the orthographic projection of the gap section (3A) at the outlet end along the axial direction of the balance drum (2).

2. The seal structure of a balance drum of a feed pump according to claim 1, wherein: along the axial direction of the balance drum sleeve (1), the inner wall of the balance drum sleeve (1) is a cylindrical surface with the same diameter;

the outer wall of balance drum (2) is divided into 2N outer wall sections (2A), two adjacent outer wall sections (2A) are distributed along balance drum sleeve (1) in a radial staggered mode, and two outer wall sections (2A) adjacent to each outer wall section (2A) are coaxial and have the same diameter.

3. The seal structure of a balance drum of a feed pump according to claim 2, wherein: the outer wall of the balance drum (2) is equally divided into 2N outer wall sections (2A).