CN111622979B

CN111622979B - Method for improving sealing reliability of third-stage mechanical seal of main pump

Info

Publication number: CN111622979B
Application number: CN202010264466.8A
Authority: CN
Inventors: 魏邦华; 陈锦裕; 田涛; 袁潮潋; 卢家良; 李宏; 吴明; 杨全超; 郑嘉榕; 文学; 江腊涛
Original assignee: CNNC Fujian Nuclear Power Co Ltd
Current assignee: CNNC Fujian Nuclear Power Co Ltd
Priority date: 2020-04-07
Filing date: 2020-04-07
Publication date: 2021-08-17
Anticipated expiration: 2040-04-07
Also published as: CN111622979A

Abstract

A method for improving the sealing reliability of a third-stage mechanical seal of a main pump comprises the following steps: s1: measuring the distance between the surface X and the surface Z and recording as a; measuring the distance between the surface Y and the surface X and recording as b; measuring the distance between the surface Y and the surface Z and recording as c; if a-b > c, a gap exists between the third-stage sealing guide ring and the mechanical sealing gland, and the size of the gap is a-b-c; s2: designing a backing ring device which is of a circular ring type; s3: the backing ring device in S2 is placed on the third machine seal guide ring.

Description

Method for improving sealing reliability of third-stage mechanical seal of main pump

Technical Field

The invention relates to the field of main pump mechanical seals, in particular to a method for improving the sealing reliability of a third-stage mechanical seal of a main pump.

Background

The main pump of a million kilowatt nuclear power primary circuit designed and manufactured by the ANDRITZ main pump introduced by the Ha electric group often has the faults of low sealing pressure of a third-level mechanical seal and high leakage rate, and the main pumps of the same types of Fuqing nuclear power 1-4 units, Fangjiashan nuclear power and Tianwan nuclear power which are transported at present have the faults of low sealing pressure of the third-level mechanical seal, so that the safe and reliable operation of the main pump is seriously influenced. Known experts such as Qinghua university, Zhejiang industrial university, main pump manufacturer and the like have been consulted for many times, but the problems still cannot be solved well. Therefore, it is desirable to develop a device for improving the sealing reliability of the third stage mechanical seal of the main pump to solve the above problems.

Disclosure of Invention

The invention aims to: and analyzing the root cause of poor reliability of the third-stage mechanical seal of the main pump, and correcting by adopting targeted measures to improve the sealing reliability of the third-stage mechanical seal of the main pump.

The technical scheme of the invention is as follows: a method for improving the sealing reliability of a third-stage mechanical seal of a main pump comprises the following steps:

s1: measuring the distance between the surface X and the surface Z and recording as a; measuring the distance between the surface Y and the surface X and recording as b; measuring the distance between the surface Y and the surface Z and recording as c; if a-b > c, a gap exists between the third-stage sealing guide ring and the mechanical sealing gland, and the size of the gap is a-b-c;

s2: designing a backing ring device which is of a circular ring type;

s3: the backing ring device in S2 is placed on the third machine seal guide ring.

The thickness of the backing ring device is a-b-c.

The backing ring device has an outer diameter of 400mm and an inner diameter of 320 mm.

And in the step S3, an upper seal gland is installed.

In S1, the distance between the plane X and the plane Z is measured with a depth gauge.

In S1, the distance between the plane Y and the plane X is measured with a depth gauge.

In S1, the distance between the plane Y and the plane Z is measured with a depth gauge.

The outside diameter of the backing ring device (2) is 400mm, and the inside diameter is 310 mm.

The outside diameter of the backing ring device (2) is 400mm, and the inside diameter is 300 mm.

The outside diameter of the backing ring device (2) is 400mm, and the inside diameter thereof is 305 mm.

Drawings

FIG. 1 is a structural diagram of a mechanical seal of a main pump according to the present invention

FIG. 2 third level seal diagram

FIG. 3 is a third stage seal stationary ring and stationary ring carrier force diagram

FIG. 4 is a view of a backing ring assembly

FIG. 5 illustrates the installation of the backing ring device

In the figure: 38 sealing chamber, 42 first stage machine seal outer ring, 43 first stage guide ring, 46 second stage machine seal outer ring, 53 second stage guide ring, 54 third stage machine seal outer ring, 57 third stage guide ring, 67 machine seal gland, 248.1 static ring seat of third stage machine seal,

A first-stage seal 11, a second-stage seal 12 and a third-stage seal 13;

face B, face X, face Y, face Z;

2 backing ring device, 4 third level machine seal ring between guide ring and the quiet ring seat, 6 third level machine seal quiet ring, 7 third level machine seal rotating ring, 8 third level machine seal rotating ring seat.

In fig. 3: the bearing capacity of a water film during normal operation F, the force of static pressure of a P seal on the static ring seat, the pre-tightening force of a third-stage mechanical seal spring F1, the friction force between the F2 seal ring and the third-stage guide ring, and the gravity of the G static ring and the static ring seat.

Detailed Description

The present invention is further described in detail with reference to the accompanying fig. 1-5.

The main pump mechanical seal device comprises a first-stage seal 11, a second-stage seal 12 and a third-stage seal 13, wherein the first-stage seal 11 comprises a first-stage guide ring 43 and a first-stage mechanical seal outer ring 42; the second-stage seal 12 comprises a second-stage guide ring 53 and a second-stage mechanical seal outer ring 46; the third-stage seal 13 comprises a third-stage machine seal outer ring 54 and a third-stage guide ring 57; wherein the second stage guide ring 53 is fixed by the third stage machine seal outer ring 54, the first stage guide ring 43 is fixed by the second stage machine seal outer ring 46, the third stage machine seal outer ring 54 is pressed by the machine seal cover 67, the machine seal cover 67 is fixed on the seal chamber 38 by bolts

As shown in fig. 2, in the third-stage seal 3, the machine seal cover 67 has mating surfaces, i.e., a surface B, a surface X, and a surface Y in the drawing, with the seal chamber 38, the third-stage machine seal outer ring 54, and the third-stage guide ring 57, respectively. The horizontal mating surface between third stage guide ring 57 and third stage mechanical seal outer ring 54 is plane Z. The third-stage mechanical seal static ring seat 248.1 is also included, and the third-stage mechanical seal static ring seat 248.1 is positioned at the lower end of the third-stage guide ring 57;

as shown in figure 4, the backing ring device 2 has an outer diameter of 400mm, an inner diameter of 320mm and a thickness of a-b-c of the backing ring device 2.

A method for improving the sealing reliability of a third-stage mechanical seal of a main pump comprises the following steps:

s1: measuring the distance between the surface X and the surface Z by using a depth gauge, and recording as a; measuring the distance between the surface Y and the surface X and recording as b; the thickness of the third stage guide ring (i.e., the distance between plane Y and plane Z) is measured and is denoted as c. If a-b > c, it means that there is a gap between the third stage seal guide ring 57 and the mechanical seal gland 67, and the gap is a-b-c.

S2: the backing ring device 2 is designed and has a thickness a-b-c, and the backing ring device 2 has an outer diameter of 400mm and an inner diameter of 320 mm.

S3: as shown in fig. 5, the backing ring device 2 in S2 is placed on the third mechanical seal guide ring 57, and the mechanical seal cover 67 is installed, so that the existing gap between the mechanical seal cover 67 and the third mechanical seal guide ring 57 is eliminated due to the backing ring device 2, and thus the third mechanical seal guide ring 57 is not limited by the backing ring device 2 to move upwards, thereby fundamentally eliminating the defects of low sealing water pressure and large leakage amount which often occur in the third mechanical seal, and improving the sealing reliability of the third mechanical seal. Meanwhile, the third-stage sealing guide ring is limited by the backing ring device not to move upwards, so that relative displacement cannot be generated between the third-stage guide ring 57 and the static ring seat 248.1 of the third-stage mechanical seal, the sealing ring between the third-stage guide ring and the static ring seat 248.1 of the third-stage mechanical seal cannot be stretched, the adhesion strength between the sealing ring and the guide ring is reduced, the adhesion abrasion between the third-stage guide ring and the sealing ring can be relieved, and the service life and the reliability of the mechanical seal are improved.

The above description is only a patent embodiment, which is an implementation manner based on the overall concept of the patent, and the protection scope of the patent is not limited thereto, and any person skilled in the art can make several modifications, improvements and substitutions within the technical scope of the disclosure, which all belong to the protection scope of the patent. Therefore, the protection scope of the patent shall be subject to the protection scope of the claims.

Claims

1. A method for improving the sealing reliability of a third-stage mechanical seal of a main pump is characterized by comprising the following steps: the method comprises the following steps:

s1: measuring the distance between the surface X and the surface Z and recording as a; measuring the distance between the surface Y and the surface X and recording as b; measuring the distance between the surface Y and the surface Z and recording as c; if a-b > c, a gap exists between the third-stage seal guide ring (57) and the mechanical seal gland (67), and the size of the gap is a-b-c;

the matching surface between the mechanical seal gland (67) and the third-stage mechanical seal outer ring (54) is a surface X;

the matching surface between the mechanical seal gland (67) and the third-stage guide ring (57) is a surface Y;

a horizontal matching surface between the third-stage guide ring (57) and the third-stage mechanical seal outer ring (54) is a surface Z;

s2: designing a backing ring device (2), wherein the backing ring device (2) is of a circular ring type;

s3: and placing the backing ring device (2) in the step S2 on a third machine seal guide ring (57).

2. The method of claim 1, wherein the method further comprises the step of: the thickness of the backing ring device (2) is a-b-c.

3. The method of claim 2, wherein the method further comprises the step of: the outside diameter of the backing ring device (2) is 400mm, and the inside diameter thereof is 320 mm.

4. The method of claim 1, wherein the method further comprises the step of: in the step S3, the backing ring device (2) in the step S2 is placed on the third mechanical seal guide ring (57), and then the upper mechanical seal cover (67) is mounted.

5. The method of claim 1, wherein the method further comprises the step of: in S1, the distance between the plane X and the plane Z is measured with a depth gauge.

6. The method of claim 1, wherein the method further comprises the step of: in S1, the distance between the plane Y and the plane X is measured with a depth gauge.

7. The method of claim 1, wherein the method further comprises the step of: in S1, the distance between the plane Y and the plane Z is measured with a depth gauge.

8. The method of claim 1, wherein the method further comprises the step of: the outside diameter of the backing ring device (2) is 400mm, and the inside diameter is 310 mm.

9. The method of claim 1, wherein the method further comprises the step of: the outside diameter of the backing ring device (2) is 400mm, and the inside diameter is 300 mm.

10. The method of claim 1, wherein the method further comprises the step of: the outside diameter of the backing ring device (2) is 400mm, and the inside diameter thereof is 305 mm.