A nuclear power plant steam opening and closing pressure difference adjustable guide valve

Abstract

The application discloses a kind of opening and closing pressure difference adjustable guide valve for nuclear power plant steam, and its opening and closing pressure difference adjusting structure includes adjusting sleeve, packing gland, sleeve and flange gland, adjusting sleeve is connected to the bottom of valve body, extends into valve cavity, lower valve flap is installed in adjusting sleeve, adjusting sleeve is sealed with the lateral wall of valve cavity by packing gland, packing gland compresses packing gland, sleeve is arranged on adjusting sleeve, flange gland is connected with the lower surface of valve body, flange gland is sealed with the inner cavity of adjusting sleeve by packing gland at the same time, and flange gland compresses packing gland.The application can conveniently and quickly adjust the opening and closing pressure difference of guide valve under the premise of ensuring the system sealing.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of for nuclear power field nuclear power plant steam opening and closing pressure difference adjustable pilot valve. BACKGROUND

[0002] The outer seal in the opening and closing pressure difference adjustment structure of the gas and liquid pilot safety valve used in the field of petrochemical industry is sealed by the contact between rubber O-ring and the threads on the adjusting sleeve.The outer seal in the opening and closing pressure difference adjustment structure of the steam pilot safety valve used in the field of petrochemical industry and thermal power station is sealed by the contact between elastic graphite and the threads on the adjusting sleeve.The system needs to be depressurized when adjusting the opening and closing pressure difference, the locking nut needs to be loosened, and the locking nut needs to be fixed after the adjustment is completed.The whole adjustment process is complex.Moreover, the sharp corners of the triangular threads can easily damage the rubber O-ring or elastic graphite, which can damage the sealing performance and require frequent replacement of new O-ring or elastic graphite seal.The steam medium in some systems of nuclear power station contains radioactivity, and the requirements for outer seal are very high.The seal needs to be reliable, the service life of the seal needs to be long, and the adjustment process needs to be simple and convenient.The pilot safety valve used in the prior art cannot meet the requirements of nuclear power station. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art, and provides a kind of opening and closing pressure difference adjustable pilot valve for nuclear power station steam, which can conveniently and quickly adjust the opening and closing pressure difference of the pilot valve under the premise of ensuring system sealing.

[0004] One technical solution to achieve the above-mentioned purpose is: a kind of opening and closing pressure difference adjustable pilot valve for nuclear power station steam, comprising a valve body, a valve disc assembly arranged in the valve cavity of the valve body, and an opening and closing pressure difference adjustment structure connected to the bottom of the valve body.

[0005] The valve disc includes an upper valve disc and a lower valve disc, and the lower valve disc is arranged at the lower part of the cavity of the valve body.

[0006] The opening and closing pressure difference adjustment structure includes an adjusting sleeve, a packing gland, a sleeve and a flange gland, the adjusting sleeve is connected to the bottom of the valve body and extends into the valve cavity, the lower valve disc is installed in the adjusting sleeve, the adjusting sleeve and the valve cavity are sealed by a packing gland, the packing gland presses the packing gland, the sleeve is arranged on the adjusting sleeve, the flange gland is connected to the lower surface of the valve body, and the flange gland is simultaneously sealed with the inner cavity of the adjusting sleeve by a packing gland, and the flange gland presses the packing gland.

[0007] Further, a window is formed in the flange gland to the sleeve.

[0008] Further, the flange gland and the inner cavity of the adjusting sleeve are sealed by a sealing structure.

[0009] Further, the sealing structure comprises an adjusting pad, a packing, a disc spring and a disc spring pad.

[0010] Further, a push rod and a push rod guide sleeve arranged in the valve cavity of the valve body are further included, and the push rod and the push rod guide sleeve are installed in the adjusting sleeve.

[0011] The nuclear power station steam opening and closing pressure difference adjustable pilot valve has the following advantages: the packing sealing technology is mature and reliable, the sealing performance is good, the risk of external leakage is avoided, the service life of the sealing element is long, and the pilot valve can be used in high temperature occasions; when the opening and closing pressure difference of the pilot valve is adjusted, the adjustment can be performed under pressure release or without pressure release; and the opening and closing pressure difference adjustment operation of the pilot valve is simple and convenient. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 FIG. 1 is a structural schematic diagram of a nuclear power station steam opening and closing pressure difference adjustable pilot valve according to the present application;

[0013] Figure 2 FIG. 2 is a detailed enlarged view of a pilot valve sensing pressure interface of the nuclear power station steam opening and closing pressure difference adjustable pilot valve according to the present application, which adopts a threaded connection structure. DETAILED DESCRIPTION

[0014] In order to better understand the technical solutions of the present application, the following will be described in detail in combination with an embodiment of an assembly process of a nuclear power station steam opening and closing pressure difference adjustable pilot valve according to the present application:

[0015] Please refer to Figure 1 The assembly process of the nuclear power station steam opening and closing pressure difference adjustable pilot valve according to the present application comprises the following steps.

[0016] 1) The lower valve disc 24 is installed in the adjusting sleeve 16.

[0017] 2) The push rod guide sleeve 27 is connected to the adjusting sleeve 16 through threads.

[0018] 3) The push rod 25 is installed in the push rod guide sleeve 27.

[0019] 4) The above components are screwed into the valve body 23 through the threads of the adjusting sleeve 16.

[0020] 5) The packing 22 is assembled into the packing box, the packing gland 19 is pressed, and the packing 22 is compressed by tightening the inner hexagonal screw 11.

[0021] 6) The sleeve 17 is installed on the adjusting sleeve 16, and the sleeve 17 is fixed by the retaining ring 15.

[0022] 7) In order, adjuster pad 14, packing 18, disc spring 20, disc spring pad 21 are assembled on flange gland 13, then flange gland assembly is assembled into adjuster sleeve 16, by tightening hexagonal socket screw 9, flange gland 13 is connected with valve body 23, packing 18 is compressed.

[0023] Adjuster sleeve 16 is connected with valve body 23 by screw thread, packing 18 and packing 22 are used for sealing inside and outside of adjuster sleeve 16, the compressed packing generates friction force on both sides of inside and outside diameter of adjuster sleeve 16, which can effectively prevent looseness of connection screw thread between adjuster sleeve 16 and valve body 23, so there is no need to specially design mechanism for preventing looseness of adjuster sleeve 16.

[0024] When pilot valve and main valve are assembled, pilot valve's sensing pressure interface 1 is connected with inlet of main valve. Its connection structure can be flange type connection structure 3 as shown in Figure 1 or can be screw thread type connection structure 4 as shown in Figure 2 .

[0025] When pilot valve is open, additional medium force is generated on lower valve disc 24 by lower valve disc 24 and push rod 25, so that pilot valve is kept open.

[0026] When it is needed to adjust opening and closing pressure difference of pilot valve, special tool is used to insert into sleeve 17 through window of flange gland 13, so as to rotate adjuster sleeve 16 to move adjuster sleeve 16 up and down. Clockwise rotation of sleeve 17 reduces opening and closing pressure difference (increases backseat pressure); counterclockwise rotation of sleeve 17 increases opening and closing pressure difference (decreases backseat pressure). By rotating sleeve 17, the purpose of adjusting opening and closing pressure difference of pilot valve is achieved.

[0027] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not used as limitation of the present application, as long as the changes and variations of the above described embodiments are within the scope of the present application.

Claims

1. A differential pressure adjustable pilot valve for nuclear power plant steam, comprising a valve body, a valve disc assembly arranged in a valve cavity of the valve body, and a opening-closing differential pressure adjusting structure connected to a bottom of the valve body, characterized in that: the valve disc comprises an upper valve disc and a lower valve disc, the lower valve disc is arranged in a lower part of the cavity of the valve body; the opening-closing differential pressure adjusting structure comprises an adjusting sleeve, a packing gland, a sleeve and a flange gland, the adjusting sleeve is connected to the bottom of the valve body and extends into the valve cavity, the lower valve disc is mounted in the adjusting sleeve, the adjusting sleeve is sealed with the valve cavity through a packing gland, the packing gland is used to compress the packing gland, the sleeve is arranged on the adjusting sleeve, the flange gland is connected with a lower surface of the valve body, the flange gland is sealed with an inner cavity of the adjusting sleeve through a packing gland, and the flange gland is used to compress the packing gland; wherein the flange gland is sealed with the inner cavity of the adjusting sleeve through a sealing structure; the sealing structure comprises an adjusting gasket, packing, a disc spring and a disc spring pad; in assembly, the adjusting gasket, packing, disc spring and disc spring pad are sequentially arranged on the flange gland in order, the flange gland is arranged in the adjusting sleeve, the flange gland is connected with the valve body by tightening an inner hexagonal screw, and the packing is compressed; the pilot valve further comprises a push rod and a push rod guide sleeve arranged in the valve cavity of the valve body, the push rod and the push rod guide sleeve are mounted in the adjusting sleeve; in assembly of the pilot valve and a main valve, a sensing pressure interface of the pilot valve is connected with an inlet of the main valve; in the case that the pilot valve is opened, an additional medium force is generated on the lower valve disc by the lower valve disc and the push rod, so that the pilot valve is kept open; when it is needed to adjust the opening-closing differential pressure of the pilot valve, a tool is inserted into the sleeve through a window of the flange gland, so that the adjusting sleeve is rotated to move up and down; the sleeve is rotated clockwise, the opening-closing differential pressure is reduced; the sleeve is rotated counterclockwise, the opening-closing differential pressure is increased, and the opening-closing differential pressure of the pilot valve is adjusted by rotating the sleeve; the window of the flange gland is arranged to the sleeve. ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The opening and closing pressure differential adjustable pilot valve for nuclear power plant steam according to claim 1, characterized by, ​

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