1. An improvement method for preventing internal leakage of a high-side pressure reducing valve is characterized by comprising the following steps:

step one, dismantling a valve seat: when the valve seat (1) is cut by using equipment, a protective blanket is arranged at the port of the pipeline to prevent foreign matters or welding slag from entering the interior of the pipeline, a layered cutting mode is adopted in the cutting process of the valve seat (1), and a flaw detector is used for searching an original welding seam after each cutting, so that a welding pool at the position of a valve body is prevented from being cut off, and a welding surface is prevented from being enlarged;

step two, reforming a sealing surface: the valve seat (1) is cut and then the pressure reducing valve is disassembled, and then a 30-degree conical sealing surface in the original pressure reducing valve is reformed and upgraded into an anti-scouring embedded double-sealing surface;

step three, arranging a protective groove: after the second step is finished, an isolation protection groove (5) for isolating impurities is formed in the root of the sealing surface of the valve core (3);

step four, installing a lantern ring: after the second step and the third step are finished, a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve (4) is additionally arranged outside the modified valve core (3) during reinstallation, and the multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve (4) is clamped and fixed between the valve cover (2) and the valve seat (1);

step five, reflow welding: after the improvement and the reinstallation are completed, the protective blanket on the pipeline is removed, then the valve seat (1) is attached to the port of the pipeline, and finally the valve seat (1) is welded and fixed with the pipeline.

2. The improvement method for preventing the internal leakage of the high-side pressure reducing valve according to claim 1, wherein the protection and reconstruction assembly in the first step and the second step is matched with the original valve body, meets the original installation requirement, reserves the original actuating mechanism, reserves the original valve body, does not reduce the performance parameters of the original regulating valve, and has the advantages of flexibility in regulation and tight shutoff.

3. The improvement method for preventing the internal leakage of the high-side pressure reducing valve according to claim 1, wherein the performance of the wear-resistant material used for modification is the same as or higher than that of the wear-resistant material of the original factory of the pressure reducing valve before modification, the function of preventing impurities generated in the start and stop of a unit from being retained on the valve seat (1) to generate scouring wear on the valve core (3) and the valve seat (1) is achieved, and the structure and the size of the modified valve core (3) and the modified valve seat (1) are consistent with those of the original valve sealing device.

4. The improvement method for preventing internal leakage of a high-side pressure reducing valve according to claim 1, wherein the noise is guaranteed to be less than or equal to 85dB when the bypass device acts under the design parameters in the improvement.

5. The improvement method for preventing the internal leakage of the high-bypass pressure reducing valve according to claim 1, wherein the valve seat (1) and the valve core (3) of the pressure reducing valve are made of F92, the hard sealing surface of the valve seat (1) is made of stellite No. 12 alloy, and the hardness of the sealing surface is HRC40-HRC 42.

6. The improvement method for preventing internal leakage of the high-bypass pressure reducing valve according to claim 1, characterized in that a new hard alloy layer is formed by overlaying welding on a sealing surface of a valve core (3) and a sealing surface of a pre-opened valve of the pressure reducing valve again, the material of the new hard alloy layer is Stellite No. 6 alloy, and the hardness of the sealing surface is HRC38-HRC 40.

7. The improvement method for preventing internal leakage of a high-bypass pressure reducing valve according to claim 1, characterized in that the material of the multi-layer staggered hole labyrinth filtering pressure reducing cage sleeve (4) is P91.

8. The improved method for preventing the internal leakage of the high bypass pressure reducing valve as claimed in claim 1, wherein in the step five, the welding part is preheated to 200 ℃ before welding, the temperature between the welding layers is not more than 300 ℃ during welding, and the welding part is preheated to 350 ℃ after welding and is kept warm for 2 h;

stress relief heat treatment, namely heating the welding part to 750-770 ℃, and slowly cooling the welding part in a temperature difference mode of not more than 150 ℃ per hour after heat preservation for 3 hours;

when the valve seat (1) and the hard alloy sealing surface of the valve core (3) are welded, all original alloy layers are required to be removed, and stellite alloy layers are resurfaced, wherein the thicknesses of all the alloy layers are not less than 3 mm; before reinstalling, the valve seat (1) is subjected to a coloring indentation test, and 100% of complete matching contact is required.

9. The utility model provides a high side relief pressure valve is prevented interior hourglass and is improved device which characterized in that, includes disk seat (1), valve gap (2), case (3) and multilayer staggered hole labyrinth filter decompression cage cover (4).

10. The improved inner leakage prevention device of the high-side pressure reducing valve according to claim 9, wherein the valve seat (1) and the valve cover (2) are respectively provided with a first groove (6) and a second groove (7) for embedding the multi-layer staggered hole labyrinth filtering pressure reducing cage sleeve (4).

Background

The high pressure reducing valve is suitable for water, steam and air medium pipelines, the inlet pressure is reduced to a certain required outlet pressure through regulation, when the inlet pressure and the flow are changed, the outlet pressure is automatically kept within a certain range by the energy of the medium, but the difference between the inlet pressure and the outlet pressure must be more than or equal to 0.2 MPA/CM.

Reference can be made to chinese patent publication No. CN101625043B, which relates to a high pressure reducing valve, in which a valve seat is provided with a throttle hole communicating an air inlet cavity and an air outlet cavity, and a valve core axially movably penetrating through the throttle hole, the valve core is provided with a throttle conical surface movably matched with a lower orifice of the throttle hole in the air inlet cavity, the upper end of the valve core is supported on a piston, the lower end of the valve core is elastically assembled in a valve body through a return spring, the throttle conical surface of the valve core is axially arranged in the middle of the air inlet cavity facing the air inlet, the lower end of the valve core is provided with a lower valve post slidably and hermetically assembled in the valve seat, and the diameter of the lower valve post is equal to the aperture of the throttle hole of the valve seat.

The above patent has the axial effort that makes the inlet pressure effect on the case be zero, can eliminate the influence of inlet pressure fluctuation to outlet pressure, has improved the advantage of steady voltage precision, but it also has the defect, like: the valve core assembly is easy to leak after being eroded by steam for a long time, and the heat economy during operation is seriously influenced.

Disclosure of Invention

The invention aims to provide an improved method and device for preventing internal leakage of a high-side pressure reducing valve, which aim to solve the problems in the background art.

In order to achieve the purpose, the invention provides the following technical scheme:

an improved method and a device for preventing internal leakage of a high-side pressure reducing valve comprise the following steps:

step one, dismantling a valve seat: when the valve seat is cut by using equipment, a protective blanket is arranged at the port of the pipeline to prevent foreign matters or welding slag from entering the pipeline, a layered cutting mode is adopted in the cutting process of the valve seat, and a flaw detection agent is used for searching an original welding seam after cutting each time, so that a welding pool at the position of the valve body is prevented from being cut, and a welding surface is prevented from being enlarged;

step two, reforming a sealing surface: the pressure reducing valve is disassembled after the valve seat is cut, and then a 30-degree conical sealing surface in the original pressure reducing valve is reformed and upgraded into an anti-scouring embedded double-sealing surface;

step three, arranging a protective groove: after the second step is finished, an isolation protection groove for isolating impurities is formed in the root of the sealing surface of the valve core;

step four, installing a lantern ring: after the second step and the third step are finished, a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve is additionally arranged outside the modified valve core during the re-assembly, and the multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve is clamped and fixed between the valve cover and the valve seat;

step five, reflow welding: after the improvement and the reinstallation are completed, the protective blanket on the pipeline is removed, then the valve seat is attached to the port of the pipeline, and finally the valve seat and the pipeline are fixed in a welding mode.

Preferably, the protection and reconstruction assembly in the first step and the second step is matched with the original valve body, meets the original installation requirement, reserves the original actuating mechanism, reserves the original valve body, does not reduce the performance parameters of the original regulating valve, and has flexible regulation and tight shutoff.

Preferably, the wear-resistant material performance used for modification is the same as or higher than that of the wear-resistant material of the original factory of the pressure reducing valve before modification, the wear-resistant material has the function of preventing sundries generated in the starting and stopping of the unit from being retained on the valve seat to generate scouring wear on the valve core and the valve seat, and the structure and the size of the modified valve core and valve seat are consistent with those of the original valve sealing device.

Preferably, the bypass device ensures that the noise is less than or equal to 85dB when the bypass device acts under the design parameters during the transformation.

Preferably, the valve seat and the valve core of the pressure reducing valve are made of F92, the hard sealing surface of the valve seat is made of stellite No. 12 alloy, and the hardness of the sealing surface is HRC40-HRC 42.

Preferably, the valve core sealing surface and the pre-opened valve sealing surface of the pressure reducing valve are formed by overlaying a new hard alloy layer made of stellite No. 6 alloy, and the hardness of the sealing surface is HRC38-HRC 40.

Preferably, the material of the multi-layer staggered hole labyrinth filtering pressure reduction cage sleeve is P91.

Preferably, in the step five reflow soldering, the soldering part is preheated to 200 ℃ before soldering, the temperature between soldering layers is not more than 300 ℃ during soldering, and the soldering part is preheated to 350 ℃ after soldering and is kept warm for 2 hours;

stress relief heat treatment: heating the welding part to 750 plus 770 ℃, and slowly cooling in a temperature difference mode of not more than 150 ℃ per hour after heat preservation for 3 hours;

when the valve seat and the hard alloy sealing surface of the valve core are welded, all original alloy layers are required to be removed, and stellite alloy layers are resurfaced, wherein the thicknesses of all the alloy layers are not less than 3 mm; the valve seat should be color-indentation tested before reinstalling, and 100% complete matching contact is necessary.

The invention also provides an improved device for preventing internal leakage of the high-side pressure reducing valve, which comprises a valve seat, a valve cover, a valve core and a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve.

Preferably, the valve seat and the valve cover are respectively provided with a first groove and a second groove for embedding the multi-layer staggered-hole labyrinth filtering pressure-reducing cage sleeve.

Compared with the prior art, the invention has the beneficial effects that:

when the high-pressure bypass pressure reducing valve is used, the original high-pressure bypass pressure reducing valve seat is upgraded to a new anti-scouring design valve seat by adding the multilayer staggered hole labyrinth type filtering pressure reducing cage sleeve in the high-pressure bypass pressure reducing valve and arranging the isolation and protection groove at the root part of the sealing surface of the valve core, and the multilayer staggered hole labyrinth type filtering pressure reducing cage sleeve is added at the valve core and the valve seat of the high-pressure bypass pressure reducing valve, so that impurities such as oxide skin in a pipeline can be effectively prevented from entering the joint surface of the valve seat and the valve core, and the effect of protecting the valve core and the valve seat is achieved; meanwhile, the root of the sealing surface of the valve core is upgraded to be provided with an isolation protection groove, so that the impurities which are filtered and are smaller than 1mm are isolated in the isolation protection groove at the moment of closing the valve, and the outer wall of the throttling mesh enclosure and the inner wall of the valve seat are protected from being damaged by the impurities to cause the jamming of the valve.

After the high-side pressure reducing valve is modified by additionally arranging a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve and arranging an isolation protection groove at the root part of a valve core sealing surface, when the temperature after the high-side pressure reducing valve is tested after the unit is started for multiple times and the unit is fully loaded, the temperature after the high-side pressure reducing valve is about 50 ℃, the high-side pressure reducing valve is closed tightly without internal leakage, and the purposes of thoroughly solving the internal leakage of the high-pressure valve, reducing the heat consumption rate of the unit and improving the operation heat economy of the unit are achieved.

Drawings

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

FIG. 2 is a structural diagram of a multi-layer staggered-hole labyrinth type filtering pressure reduction cage sleeve of the invention;

FIG. 3 is a block diagram of the present invention at the location of the isolation protection slot;

FIG. 4 is a flow chart of the method of the present invention.

In the figure: 1. a valve seat; 2. a valve cover; 3. a valve core; 4. a multi-layer staggered hole labyrinth type filtering pressure reduction cage sleeve; 5. an isolation protection groove; 6. a first groove; 7. a second groove.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 4, the invention provides an improved method for preventing internal leakage of a high-bypass pressure reducing valve, which comprises the following steps:

step one, valve seat 1: when the valve seat 1 is cut by using equipment, a protective blanket is arranged at the port of the pipeline to prevent foreign matters or welding slag from entering the interior of the pipeline, a layered cutting mode is adopted in the cutting process of the valve seat 1, a flaw detector is used for searching an original welding seam after each cutting, a welding pool at the position of a valve body is prevented from being cut, and a welding surface is prevented from being enlarged;

step two, manufacturing a sealing surface: the valve seat 1 is disassembled after being cut, and then a 30-degree conical sealing surface in the original pressure reducing valve is reformed and upgraded into an anti-scouring embedded double-sealing surface;

step three, arranging a protection groove: after the second step is finished, an isolation protection groove 5 for isolating impurities is formed in the root of the sealing surface of the valve core 3;

step four, sleeving a cage: after the second step and the third step are completed, a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve 4 is additionally arranged outside the modified valve core 3 during the resetting, and the multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve 4 is clamped and fixed between the valve cover 2 and the valve seat 1;

step five, welding: after the improvement and the reinstallation are completed, the protective blanket on the pipeline is removed, then the valve seat 1 is attached to the port of the pipeline, and finally the valve seat 1 is welded and fixed with the pipeline.

In this embodiment, preferably, the protection and reconstruction assembly in the first step and the second step is matched with the original valve body, meets the original installation requirement, retains the original actuating mechanism and the original valve body, does not reduce the performance parameters of the original regulating valve, and has flexibility in regulation and tight shutoff.

In this embodiment, preferably, the wear-resistant material used for modification has the same or higher performance than the wear-resistant material of the original manufacturer of the pressure reducing valve before modification, and has a function of preventing impurities generated during the start and stop of the unit from being retained on the valve seat 1 to generate erosion wear on the valve element 3 and the valve seat 1, and the structure and the size of the valve element 3 and the valve seat 1 after modification are consistent with those of the original valve sealing device.

In this embodiment, it is preferable that the bypass device is configured to ensure that the noise is less than 85dB when operating under the design parameters during the modification.

In this embodiment, the valve seat 1 and the valve element 3 of the pressure reducing valve are preferably made of F92, the hard sealing surface of the valve seat 1 is stellite 12 alloy, and the hardness of the sealing surface is HRC 42.

In this embodiment, preferably, the new hard alloy layer is formed by overlaying welding on the sealing surface of the valve element 3 and the sealing surface of the pre-opened valve of the improved pressure reducing valve, the material of the new hard alloy layer is stellite No. 6 alloy, and the hardness of the sealing surface is HRC 40.

In this embodiment, the material of the multi-layer labyrinth filtering pressure reducing cage 4 is preferably P91.

In the embodiment, preferably, in the step five reflow soldering, the soldering position is preheated to 180 ℃ before soldering, the temperature between soldering layers is 270 ℃ during soldering, and the soldering position is preheated to 320 ℃ after soldering and is kept warm for 2 hours;

stress relief heat treatment: heating the welding part to 760 ℃, preserving the temperature for 3 hours, and then slowly cooling in a temperature difference mode of 120 ℃ per hour;

when the valve seat 1 and the hard alloy sealing surface of the valve core 3 are welded, the original alloy layers are required to be completely removed, and stellite alloy layers are resurfaced, wherein the thicknesses of all the alloy layers are 5 mm; the valve seat 1 should be color-indentation tested before reinstalling, and 100% complete matching contact is necessary.

The invention also provides an improved device for preventing internal leakage of the high-side pressure reducing valve, which comprises a valve seat 1, a valve cover 2, a valve core 3 and a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve 4.

In this embodiment, preferably, the valve seat 1 and the valve cover 2 are respectively provided with a first groove 6 and a second groove 7 for embedding the multi-layer staggered-hole labyrinth filtering pressure-reducing cage 4.

The working principle and the using process of the invention are as follows:

when the high-pressure bypass pressure reducing valve internal leakage prevention improvement method and the device thereof are used, the multilayer staggered hole labyrinth type filtering pressure reducing cage sleeve 4 is added in the high-pressure bypass pressure reducing valve, the root part of the sealing surface of the valve core 3 is provided with the isolation protection groove 5, the original high-pressure bypass pressure reducing valve seat 1 is upgraded into a new anti-scouring design valve seat 1, and the multilayer staggered hole labyrinth type filtering pressure reducing cage sleeve 4 is added at the valve core 3 and the valve seat 1 of the high-pressure bypass pressure reducing valve, so that impurities such as oxide skin in a pipeline can be effectively prevented from entering the joint surface of the valve seat 1 and the valve core 3, and the effect of protecting the valve core 3 and the valve seat 1 is achieved; meanwhile, the root of the sealing surface of the valve core 3 is upgraded to be provided with an isolation protection groove 5, so that the impurities which are filtered and are smaller than 1mm are isolated in the isolation protection groove 5 at the moment of closing the valve, and the outer wall of the throttling mesh enclosure and the inner wall of the valve seat 1 are protected from being strained by the impurities to cause valve jamming.

After the high-side pressure reducing valve is modified by additionally arranging a multi-layer staggered hole labyrinth type filtering pressure reducing cage sleeve 4 and arranging an isolation protection groove 5 at the root part of the sealing surface of a valve core 3, when the temperature after the high-side pressure reducing valve is tested after the unit is started for multiple times and the unit is fully loaded, the temperature after the high-side pressure reducing valve is about 50 ℃, the high-side pressure reducing valve is tightly closed without internal leakage, and the purposes of thoroughly solving the internal leakage of the high-pressure valve, reducing the heat consumption rate of the unit and improving the operation heat economy of the unit are achieved.

Analysis of internal leakage cause of high-side pressure reducing valve

The main reasons may be the following:

1. at the moment of closing the high-pressure side valve reducing valve, because sundries such as oxide skin and the like are easy to remain at the positions of the valve core and the valve seat, and simultaneously, because the hard stellite alloy sealing surface of the valve core and the valve seat becomes thinner gradually after being ground each time, the damage and the failure of the sealing surface of the valve are caused, and the internal leakage of the valve is generated;

2. the temperature of steam at the inlet of the valve is high, and the temperature of the temperature-reduced water at the outlet is low, so that the generated temperature difference causes overlarge thermal stress at the sealing part of the valve core and the valve seat, and deformation is generated to cause sealing leakage;

3. when the valve is opened, the valve core is flushed by water vapor, a large amount of wet steam is flushed on the valve core in the machine starting process of the unit, the steam speed is high and reaches 100m/s, when the water drops are in the clamping band part, the valve core is flushed greatly, and the sealing surface of the valve is always flushed and damaged by starting once. Meanwhile, as the drainage of the drainage pipeline is not clean, water drops are contained in steam, cavitation and erosion are generated at the moment of closing the valve, and the sealing surface of the valve is damaged.

And (3) eliminating internal leakage of the high bypass pressure reducing valve:

1. redesigns and manufactures the in-valve assembly, and the new in-valve assembly is matched with the original valve body, accords with the original installation requirement, reserves the original actuating mechanism, reserves the original valve body (namely only replaces the in-valve assembly), does not reduce the performance parameters, the flexibility of adjustment and the like of the original regulating valve, and is tightly shut off. By adding the multi-layer labyrinth filtering pressure reduction cage sleeve, particle impurities larger than 1mm can be filtered, the initial flow rate of main steam can be reduced, and the sealing surface of a valve core and a valve seat is protected;

2. the original 30-degree conical sealing surface is improved into an anti-scouring embedded double-sealing surface design, has elastic self-compensation and self-protection performances, and can keep tight sealing for a long time;

3. the root of the sealing surface of the valve core is upgraded to a design with a protection groove, so that the impurities which are filtered and are smaller than 1mm are isolated in the groove at the moment of closing the valve, and the outer wall of the throttling net cover and the inner wall of the valve seat are protected from being pulled by the impurities to cause the jamming of the valve.

4. The wear-resistant material of the valve core and the valve seat of the high-pressure bypass pressure reducing valve after the transformation is equal to or higher than the material of the original manufacturer of the high-pressure bypass pressure reducing valve before the transformation, and the valve core and the valve seat have the function of preventing sundries generated in the starting and stopping of a unit from being retained on the valve seat to generate erosive wear to the valve core and the valve seat. The structure and the size of the original valve sealing device cannot be changed by the valve core and the valve seat after transformation, and the situation that the sealing device is changed from a standard part to a non-standard part after transformation to cause difficulty in subsequent maintenance is prevented. And the leakage caused after the transformation is prevented.

5. The wear-resistant material of the valve core and the valve seat of the high-pressure bypass pressure reducing valve after the transformation is equal to or higher than the material of the original manufacturer of the high-pressure bypass pressure reducing valve before the transformation, and the valve core and the valve seat have the function of preventing sundries generated in the starting and stopping of a unit from being retained on the valve seat to generate erosive wear to the valve core and the valve seat. The noise of the bypass device must not exceed 85db (a) (spatial range 1 meter from the device) when operating under design parameters.

The specific working contents of the high-side pressure reducing valve with the anti-scouring device are as follows:

material requirement of filtering device

The material of the valve seat and the valve core of the high-pressure bypass reducing valve is F92, the material of the hard sealing surface of the valve seat requires Stellite No. 12 alloy, and the hardness of the sealing surface is HRC 40-42. The new hard alloy layer material of the valve core sealing surface of the high-pressure bypass reducing valve and the sealing surface of the pre-opened valve is stellite No. 6 alloy, and the hardness of the sealing surface is HRC 38-40. The through-flow capacity of the valve after the filter device is added is ensured not to be smaller than the original design value of the valve, the newly-added anti-scouring device belongs to a multi-layer staggered hole labyrinth type filtering pressure reduction cage sleeve, and the anti-scouring device is made of P91 and can effectively filter impurities more than 1 mm.

Valve seat dismantling process

In the transformation process of the valve, especially when the valve seat is cut and welded, pipeline protection measures are required to be taken, and foreign matters or welding slag are prevented from entering the pipeline and damaging equipment. In the cutting process of the valve seat, the valve seat is cut in a layered mode, the original welding seam is searched by using a flaw detection agent after each cutting, and a welding pool at the position of the valve body is cut as few as possible so as to avoid the expansion of a welding surface.

Valve seat back-assembling welding process

The welding mode is as follows: and performing TIG bottoming and manual facing, preheating to 200 ℃ in advance before welding, wherein the temperature between welding layers is not more than 300 ℃, and preheating to 350 ℃ in sequence after welding and preserving heat for 2 hours. And (4) stress relief heat treatment, heating to 750-770 ℃, and slowly cooling in a temperature difference mode of not more than 150 ℃ per hour after the heat preservation time is 3 hours. Welding the hard alloy sealing surfaces of the valve seat, the valve core and the pre-starting valve requires that the original alloy layers are all removed from the valve core and the pre-starting valve, the stellite alloy layers are re-welded, and the thickness of all the alloy layers is not less than 3 mm. Before the valve is installed again, the valve is turned on by a user, and the valve seat is subjected to a coloring and indentation test, and 100% of complete matching contact is required.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.