A high-performance full-opening safety valve with back pressure control and a back pressure control method and pressure container system thereof

Abstract

The present application relates to a kind of high-performance full-opening safety valve of back pressure control and its back pressure control method and pressure vessel system.Back pressure control high-performance full-opening safety valve, including valve body assembly and load control assembly;Valve body assembly includes coaxially assembled valve seat, guide back pressure base and valve cover, and the sealed connection forms back pressure chamber;Load control assembly includes coaxially arranged valve flap assembly, spring and adjusting screw;Guide back pressure base integrates the guide function of valve flap assembly, limiting function and back pressure control function: realize guide function by the gap cooperation between its inner wall and valve flap assembly;Limiting structure in its lower end limits the opening height of valve flap assembly to realize limiting function;Back pressure control function is realized by the slot hole of the base center being set to connect the flow channel of valve seat with the back pressure chamber;And safety valve as a whole does not set any adjusting ring.Effectively solve the problem that the performance of overpressure and backseat pressure is mutually exclusive in traditional safety valve for a long time, and ensure that the discharge process is stable, avoid the frequency vibration phenomenon.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mechanical engineering, in particular to a back pressure controlled high-performance full-opening safety valve, a back pressure control method thereof and a pressure vessel system, and more particularly to a safety valve with low opening and closing pressure difference and without adjusting ring through an innovative design of a guide back pressure base and a slot structure. BACKGROUND

[0002] A core contradiction of traditional full-opening safety valves is that, according to the GB / T12243-2021 standard, the back seat pressure needs to be greater than or equal to 85% of the set pressure, and the overpressure needs to be less than or equal to 110% of the set pressure, which results in an opening and closing pressure difference of up to about 25%. In actual applications, because the overpressure and back seat pressure performance are mutually exclusive, the opening and closing pressure difference of conventional safety valves is generally close to 25%. This means that after discharge, the system pressure needs to drop by about 25% to close the back seat, resulting in a large waste of valuable medium.

[0003] To solve the problem of high opening and closing pressure difference, the prior art adds 1-2 adjusting rings to the safety valve. Although the adjusting ring can adjust the back seat pressure, it has the following significant disadvantages: 1. Performance is mutually exclusive: when the back seat pressure is increased, the overpressure will inevitably deteriorate; conversely, optimizing the overpressure will result in a decrease in back seat pressure. It is difficult to achieve low overpressure and high back seat pressure at the same time. 2. Complex structure and leakage risk: the adjusting ring needs to be installed and fixed by a top pin through a threaded hole machined on the valve body, which increases additional parts and potential leakage points. 3. Increased cost: the adjustment process is tedious and requires repeated adjustment of the adjusting ring position, significantly increasing production and time costs. 4. Frequency vibration problem: during the adjustment or operation process, improper or slight changes in the adjusting ring position can easily cause the safety valve to vibrate violently in the discharge state, which not only damages the valve itself, but also may endanger the safe operation of the connected equipment.

[0004] Therefore, there is an urgent need for a full-opening safety valve without adjusting ring, which can automatically achieve low opening and closing pressure difference and ensure stable discharge process, as well as a back pressure control method thereof and a pressure vessel system. SUMMARY

[0005] The present application aims to provide a back pressure controlled high-performance full-opening safety valve, a back pressure control method thereof and a pressure vessel system, which, through the valve seat and valve cover pressure difference self-balancing principle, replaces the traditional adjusting ring structure, achieves an opening and closing pressure difference ≤ the value of overpressure minus back seat pressure, i.e. opening and closing pressure difference ≤ 5% of the set pressure, without any adjusting ring, effectively solves the long-standing problem of performance mutual exclusion between discharge pressure and back seat pressure of traditional safety valves, ensures stable discharge process, and avoids frequency vibration phenomenon.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] According to a first aspect of the present application, a high-performance full-opening safety valve with back pressure control is provided, comprising a valve body assembly and a load control assembly; the valve body assembly comprises a valve seat, a guide back pressure base and a valve cover coaxially assembled and sealedly connected to form a back pressure chamber;

[0008] The load control assembly comprises a valve disc assembly, a spring and an adjusting screw coaxially arranged;

[0009] The guide back pressure base integrates the guide function, the limiting function and the back pressure control function of the valve disc assembly: the guide function is realized by the gap cooperation between the inner wall of the guide back pressure base and the valve disc assembly; the limiting function is realized by the limiting structure at the lower end of the guide back pressure base to limit the opening height of the valve disc assembly; the back pressure control function is realized by the groove hole in the center of the guide back pressure base to connect the flow passage of the valve seat and the back pressure chamber;

[0010] And the safety valve as a whole does not set any adjusting ring.

[0011] As an option, two symmetrically arranged groove holes are arranged on the guide back pressure base.

[0012] The total flow area of the groove holes meets the following two conditions: less than one sixth of the throat diameter area of the safety valve, and less than one sixtieth of the area of the backflush disc of the valve disc assembly.

[0013] As an option, the groove holes are located in the upper region of the backflush disc of the valve disc assembly.

[0014] And when the safety valve is in a full-opening discharge state, the upper end surface of the valve disc assembly abuts against the lower end surface of the guide back pressure base, so that the medium flowing through the groove holes needs to change the flow direction to form a detour path, thereby delaying the pressure rise in the back pressure chamber.

[0015] As an option, the area of the backflush disc of the valve disc assembly is 9.2 times the throat diameter area of the safety valve.

[0016] As an option, the discharge outlet area of the safety valve meets the following two conditions: greater than three times the throat diameter area of the safety valve, and greater than thirty times the total area of the two groove holes.

[0017] As an option, the performance parameters of the safety valve meet: the opening and closing pressure difference ≤ the value of the excess pressure minus the back seat pressure, i.e. the opening and closing pressure difference ≤ 5% of the set pressure, the back seat pressure ≥ 96% of the set pressure, and the excess pressure ≤ 101% of the set pressure.

[0018] As an option, the opening height of the valve disc assembly limited by the guide back pressure base is greater than or equal to one fourth of the throat diameter of the safety valve.

[0019] According to a second aspect of the present application, a back pressure control method for the full-opening safety valve is provided, comprising:

[0020] Discharge phase: when the valve disc assembly abuts against the guide back pressure base, the medium flow through the slot hole needs to change the flow direction to form a detour path, which blocks the medium from flowing into the back pressure chamber and delays the pressure rise in the back pressure chamber;

[0021] Return phase: when the system pressure is lower than the set pressure, the medium gradually flows into the back pressure chamber through the slot hole, causing the pressure in the back pressure chamber to slowly rise and approach the system pressure; the rising back pressure and the spring pre-tightening force jointly act on the upper end of the valve disc assembly, driving the valve disc assembly to achieve sealing when the system pressure is greater than or equal to 96% of the set pressure.

[0022] As an option, during the return phase, when the pressure in the back pressure chamber rises to approach the system pressure, the back pressure and the spring pre-tightening force jointly act, causing the valve disc assembly to achieve return sealing when the system pressure is greater than or equal to 96% of the set pressure.

[0023] According to a third aspect of the present application, a pressure vessel system is provided, comprising the full-opening safety valve described above, for overpressure protection of gas manufacturing, storage or transportation equipment.

[0024] The advantages of the present application are:

[0025] 1. Ultra-low opening and closing pressure difference: through the unique design of the guide back pressure base and the slot hole, the opening and closing pressure difference ≤ the value of the overpressure minus the return pressure, i.e. the opening and closing pressure difference ≤ 5% of the set pressure, which is much better than the about 25% required by the GB / T12243-2021 standard, significantly reducing the discharge loss of precious medium.

[0026] 2. Performance synergy optimization: overcoming the inherent contradictions of traditional safety valves with adjusting rings, while achieving low overpressure and high return pressure.

[0027] 3. Structure simplification and high reliability: completely eliminating the adjusting ring, the plunger and the installation screw hole, eliminating the leakage points and potential failure points caused thereby, reducing the number of parts, and making the structure more simple and reliable.

[0028] 4. Low cost and high efficiency: eliminating the machining, installation and tedious debugging process of the adjusting ring, significantly reducing the manufacturing cost and debugging time cost.

[0029] 5. Discharge stability: in the full-opening discharge state, the upper end surface of the valve disc abuts against the lower end surface of the guide back pressure base, and the detour path formed by the slot hole effectively delays the pressure rise in the back pressure chamber, causing the valve disc to be stably supported on the base, thereby fundamentally avoiding the frequency vibration problem during discharge of the safety valve. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0031] Figure 1 The overall structure sectional view of the full-opening safety valve according to the embodiments of the present application;

[0032] Figure 2 The flowchart of the safety valve back pressure control method according to the present application;

[0033] Figure 3 The structure schematic diagram of the guide back pressure base according to the present application.

[0034] In the figure, 1, valve seat; 2, valve disc assembly; 3, guide back pressure base; 4, valve cover; 5, spring; 6, adjusting screw; 7, backflushing disc; 8, slot hole; 9, back pressure chamber; 10, valve shell; A, throat diameter. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments only constitute some embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0036] Embodiment one

[0037] As shown in Figure 1 and Figure 3 , a back pressure controlled high performance full-opening safety valve includes a valve body assembly and a load control assembly; the valve body assembly includes a valve seat 1, a guide back pressure base 3 and a valve cover 4 coaxially assembled and sealedly connected to form a back pressure chamber 9;

[0038] The load control assembly includes a valve disc assembly 2, a spring 5 and an adjusting screw 6 coaxially arranged;

[0039] The guide back pressure base 3 integrates the guide function, the limiting function and the back pressure control function of the valve disc assembly 2: the guide function is realized by the gap cooperation between the inner wall of the guide back pressure base 3 and the valve disc assembly 2; the limiting function is realized by the limiting structure at the lower end of the guide back pressure base 3 to limit the opening height of the valve disc assembly 2; the back pressure control function is realized by the slot hole 8 in the center of the guide back pressure base 3 to connect the flow passage of the valve seat 1 and the back pressure chamber 9;

[0040] And the safety valve as a whole does not set any adjusting ring.

[0041] The advantages are: canceling the adjusting ring, eliminating the leakage point and debugging cost, reducing the number of parts; single component solves the problems of guiding, limiting, back pressure control, and compact structure; the back pressure cavity delays pressure transmission to avoid high frequency vibration of the traditional safety valve.

[0042] The back pressure control refers to controlling the flow rate and time delay of the medium flowing into the back pressure cavity through adjusting the total area of the slot holes 8 (≤ 1 / 6 of the throat diameter area and ≤ 1 / 60 of the area of the backflush disc 7) and the detour path design. When the total area of the slot holes 8 is too large, the pressure in the back pressure cavity rises instantaneously, resulting in frequency vibration; when the total area of the slot holes 8 is too small, the back pressure rises too slowly to assist the reseating.

[0043] After using the back pressure control, the precision of the backflush disc 7 does not need to be very high, and it is relatively easy to achieve a small opening and closing pressure difference. The traditional safety valve is controlled by the adjusting ring. The safety valve of the present application is a value obtained through a full performance test, and the diameter of the backflush disc 7 and the depth of the backflush disc 7 are modified according to the test data each time to determine the final data ratio parameters.

[0044] In specific experimental tests: first, the upper part must be fully sealed, and the valve cap is removed or a small hole is punched on the bonnet 4, so that the upper part will not produce back pressure, and the reseating pressure is less than 85% of the set pressure. Otherwise, the upper part is fully sealed, and the reseating pressure is greater than or equal to 96% of the set pressure.

[0045] Secondly, the back pressure control is realized through the area of the slot holes 8 on the guiding back pressure seat 3 and the detour route. Through experiments, first, a route with two light holes with a diameter of 5 mm and no right angle is used to directly pass to the chamber of the bonnet 4. Due to the large area of the hole, the gas enters the chamber of the bonnet 4 too fast, which will cause frequency vibration. On the contrary, through experiments, the appropriate area of the slot holes 8 on the guiding back pressure seat 3 is determined, and a detour route is set for the gas entering the chamber of the bonnet 4, so that frequency vibration will not occur.

[0046] In the embodiment, two symmetrical slot holes 8 are formed on the guiding back pressure seat 3; the total flow area of the two slot holes 8 meets the following two conditions: less than one sixth of the throat diameter area of the safety valve, and less than one sixtieth of the area of the backflush disc 7 of the valve disc assembly 2. The small hole area limits the medium inflow speed and delays the pressure rise in the back pressure cavity; the double hole design avoids the single side flow impact leading to the valve disc abrasion.

[0047] In the embodiment, the slot holes 8 are located in the upper region of the backflush disc 7 of the valve disc assembly 2; and when the safety valve is in a full opening discharge state, the upper end surface of the valve disc assembly 2 abuts against the lower end surface of the guiding back pressure seat 3, so that the medium flowing through the slot holes 8 needs to change the flow direction to form a detour path, thereby delaying the pressure rise in the back pressure chamber 9.

[0048] The position of the two slots 8 is tested by experiment, one of the slots 8 is close to the outlet of the safety valve, and the other slot 8 is at the deepest position in the chamber of the valve shell 10. At this time, the reset pressure is close to 96% of the set pressure. When two slots 8 are arranged in the valve shell 10 at the same time, the reset pressure is about 90%-93% of the set pressure.

[0049] In this embodiment, the area of the backflush disc 7 of the valve disc assembly 2 is 9.2 times the area of the throat diameter of the safety valve. The opening force is increased by 3 times, and the overpressure is only 101% of the set pressure; the unit area sealing force is ≥15MPa when resetting.

[0050] In this embodiment, the area of the discharge outlet of the safety valve meets the following two conditions: greater than three times the area of the throat diameter of the safety valve, and greater than thirty times the total area of the two slots 8. The outlet flow resistance is reduced by 42%, and the discharge efficiency is improved; the large outlet area avoids the overpressure feedback to the back pressure chamber.

[0051] In this embodiment, the performance parameters of the safety valve meet: the opening and closing pressure difference is ≤5% of the set pressure, the reset pressure is ≥96% of the set pressure, and the overpressure is ≤101% of the set pressure. Compared with 25% opening and closing pressure difference, 20% precious medium is saved; far exceeding the standard of GB / T12243-2021.

[0052] In this embodiment, the guide back pressure base 3 limits the opening height of the valve disc assembly 2 to be greater than or equal to one fourth of the diameter of the throat diameter of the safety valve. It ensures that the discharge flow is ≥95% of the theoretical value; and avoids that the spring 5 cannot reset due to insufficient force caused by excessive height.

[0053] The limiting of the valve disc assembly 2 mainly depends on the thickness of the guide back pressure base 3, which is fixed between the valve shell 10 and the valve cover 4, so the guide back pressure base 3 is a fixed part. When the valve disc assembly 2 discharges, the valve disc assembly 2 will be limited when it is attached to the guide back pressure base 3, and the opening height ≥1 / 4 of the valve body flow passage diameter can be controlled by controlling the thickness of the guide back pressure base 3. When the full-opening safety valve is defined, the opening height of the valve disc must be ≥1 / 4 of the valve body flow passage diameter.

[0054] In this embodiment, the reason why there is no frequency shock during the discharge stage is that in order to reduce the value of the overpressure, the area of the valve disc is increased and the depth of the backflush disc 7 is deepened, and the corresponding overpressure is very close to the set pressure. When the system pressure is slightly higher than the set pressure, the valve disc assembly 2 will take off and be steadily dragged at the limiting position of the valve disc assembly 2 by the gas in the system pressure.

[0055] In the back-to-seat stage, the setting of the setting pressure is generally within 1.1 times of the system pressure, and if it is the safety valve of the present application, the setting pressure can be set to 1.03 times of the system pressure (such as the multiple relationship), so that the back-to-seat pressure can return to the system pressure. Moreover, the entire opening and closing pressure difference can be changed in this way, and the outer diameter or depth of the backflush disc 7 of the lower valve disc can also achieve an opening and closing pressure difference ≤10%. The opening and closing pressure difference ≤5% of the setting pressure mentioned in the current invention patent is the best data in the experiment, and the smaller the opening and closing pressure difference, the more energy-saving.

[0056] As shown in Figure 2 The back pressure control method of the full-opening safety valve of the present embodiment comprises:

[0057] The discharge stage: when the valve disc assembly 2 abuts against the guide back pressure base 3, the medium flowing through the slot hole 8 needs to change the flow direction to form a detour path, block the medium flowing into the back pressure chamber 9, and delay the pressure rise in the back pressure chamber 9;

[0058] The back-to-seat stage: when the system pressure is lower than the setting pressure, the medium gradually flows into the back pressure chamber 9 through the slot hole 8, so that the pressure in the back pressure chamber 9 slowly rises and approaches the system pressure; the rising back pressure cooperates with the pre-tightening force of the spring 5 to act on the upper end of the valve disc assembly 2, and drives the valve disc assembly 2 to realize sealing when the system pressure is greater than or equal to 96% of the setting pressure.

[0059] The specific principles or steps are as follows: operation steps:

[0060] When installing the valve disc assembly 2, there are two slot holes 8, so that one slot hole 8 is closest to the outlet position of the safety valve.

[0061] The sealing stage: the medium pressure is within 90% of the setting pressure of the safety valve. By rotating the adjusting screw 6, the spring 5 is compressed, so that the valve disc assembly 2 and the sealing surface of the valve body generate a pre-tightening force, the medium enters the flow passage in the safety valve seat 1, and the flow passage diameter adopts the Venturi effect. When the flow passage diameter is close to the reduced flow section, the value of the medium pressure exceeding the pressure in the later stage is reduced.

[0062] The pre-discharge stage: when the medium pressure starts to rise and approaches about 97%~100% of the setting pressure of the safety valve, the safety valve starts to slightly leak, the medium passes through the valve seat 1, and the direction of the medium is downward through the backflush disc 7 in the valve disc assembly 2, and the valve disc assembly 2 is in the center of the outlet of the safety valve. The area of the two slot holes 8 should be less than 1 / 6 of the throat diameter area and less than 1 / 60 of the area of the backflush disc 7 according to the test, the slot hole 8 is located at the upper end of the backflush disc 7 of the safety valve disc, so that the medium discharged through the valve body is discharged from the outlet of the safety valve, and the pressure at the valve cover 4 of the safety valve does not rise.

[0063] The take-off stage: when the medium pressure reaches the setting pressure, the valve disc rapidly rises due to the increase of the area of the backflush disc 7.

[0064] Discharge stage: when the medium pressure reaches 101% of the set pressure, the valve disc assembly 2 will be instantaneously pushed to the guide back pressure base 3, at this time the upper end of the valve disc and the two slot holes 8 of the guide back pressure base 3 form a right angle in a detour route, so that the internal pressure at the valve cover 4 does not immediately rise, so that the valve disc is stably supported on the guide back pressure base 3. The guide back pressure base 3 also limits the opening height of the safety valve, avoiding the opening height of the valve disc assembly 2 being too high, resulting in the safety valve not being able to be closed.

[0065] Seating stage: when the medium pressure is discharged below the set pressure of the safety valve, the medium slowly enters the valve cover 4 through the two detour slot holes 8, the pressure at the valve cover 4 starts to rise close to the medium pressure, thereby generating a back pressure at the valve cover 4, the area of the two slot holes 8 is less than 1 / 60 of the area of the rebound disc 7, the internal pressure cannot be quickly released, and acts on the valve disc assembly 2, plus the pre-tightening force of the spring 5 on the valve disc, when the medium pressure reaches 96% of the set pressure, the valve disc and the valve body are quickly sealed.

[0066] The opening and closing pressure difference of the final safety valve is within 5%.

[0067] In the seating stage, when the pressure in the back pressure chamber 9 rises close to the system pressure, the back pressure and the pre-tightening force of the spring 5 jointly act on the valve disc assembly 2 to achieve seating sealing when the system pressure is greater than or equal to 96% of the set pressure.

[0068] Example two

[0069] A pressure vessel system comprising the above full-opening safety valve for overpressure protection of gas manufacturing, storage or transportation equipment.

[0070] Taking a specific safety valve for a hydrogen storage cylinder as an example, the design pressure of the hydrogen storage cylinder is 70 MPa, the set pressure of the safety valve is 70 MPa, and it is used for storing hydrogen.

[0071] The throat diameter is 20 mm, the throat area is π×(10)²=314 mm², the rebound disc area is 9.2 times the throat area, that is, 9.2×314=2890 mm², the corresponding rebound disc diameter is 61 mm, the slot hole is a semicircular hole, the radius of each slot hole is 3.9 mm, and the total area of the slot hole is 2×π×3.9² / 2=47.8 mm²; less than 1 / 6 of the throat area, 314 / 6=52.3 mm²>47.8 mm²; less than 1 / 60 of the rebound disc area, 2890 / 60=48.2 mm²>47.8 mm²; the discharge outlet area is greater than 3 times the throat area (942 mm²), and greater than 30 times the total area of the slot hole (1434 mm²), the design discharge outlet diameter is 44 mm; the opening height is greater than 1 / 4 of the throat diameter, 20 / 4=5 mm, and the design is 5.5 mm.

[0072] Example three, hydrogen storage tank application effect comparison:

[0073] The natural gas storage tank truck using the traditional safety valve has a volume of 25.1m 3 , a gas pressure of 20 MPa, stores natural gas, the safety valve setting pressure is 20 MPa, the overpressure is ≤110% of the setting pressure, that is, 22 MPa, the backseat pressure is ≥85% of the setting pressure, that is, 17 MPa, and the opening and closing pressure difference is 25%, that is, 5 MPa. When the pressure rises to 22 MPa, the safety valve is fully opened for discharge, and needs to be discharged to 17 MPa to be back seated and closed. At 20 MPa, 1m 3 of natural gas is 1000 yuan, and the single loss is about 6000 yuan.

[0074] The hydrogen storage tank using the full-opening safety valve of the application has a volume of 25.1m 3 , a design pressure of 20 MPa, and an opening and closing pressure difference ≤5% of the setting pressure, which is calculated as the maximum 5%, compared with the traditional safety valve, more than 80% is saved.

[0075] Example four, safety valve is applied to hydrogenation station:

[0076] The hydrogenation station as the core infrastructure of the hydrogen fuel cell vehicle needs to be equipped with a safety valve for the high-pressure hydrogen storage tank, the hydrogen compressor set outlet pipeline and the high-pressure hose of the hydrogenation machine to prevent equipment overpressure explosion. The traditional safety valve has a large opening and closing pressure difference, about 25%, which leads to a large amount of hydrogen waste in frequent opening and closing of hydrogenation operation, and the frequency vibration problem caused by the adjusting ring threatens the pipeline sealing.

[0077] After three tests:

[0078]

[0079] The overpressure is ≤101% of the setting pressure, the backseat pressure is ≥96% of the setting pressure, and the opening and closing pressure difference is ≤5% of the setting pressure. In a low-pressure large-volume system, the absolute value of the opening and closing pressure difference is small, and the total amount of medium brought by the volume amplification can achieve more significant cost savings. Taking the 20 MPa natural gas storage tank truck as an example, about 1 kg of natural gas is saved, and the cost is saved about 1000 yuan.

[0080] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. Any skilled person in the art can easily think of changes or replacements within the scope of the disclosed technology, which should be covered within the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.

Claims

1. A high-performance full-lift safety valve with back pressure control, comprising a valve body assembly and a load control assembly; characterized in that: The valve body assembly includes a coaxially assembled valve seat, a guide back pressure base and a valve cover, the three of which are sealed and connected to form a back pressure chamber; The load control assembly includes a coaxially arranged valve disc assembly, a spring and an adjusting screw; The guide back pressure base integrates the guiding function, limiting function and back pressure control function of the valve disc assembly: the guiding function is achieved by the clearance between its inner wall and the valve disc assembly; the limiting function is achieved by limiting the opening height of the valve disc assembly through the limiting structure at its lower end; and the back pressure control function is achieved by connecting the valve seat flow channel and the back pressure chamber through the slot opened in the center of the base. The safety valve as a whole is not provided with any adjustment ring; The guide back pressure base is provided with two symmetrically arranged slots; The total flow area of ​​the slots meets the following two conditions: less than one-sixth of the throat diameter area of ​​the safety valve and less than one-sixtieth of the recoil disc area of ​​the valve disc assembly; The slot is located in the upper area of ​​the recoil disc of the valve disc assembly; When the safety valve is in the fully open discharge state, the upper end surface of the valve flap assembly abuts against the lower end surface of the guide back pressure base, so that the medium needs to change its flow direction when flowing through the slot hole, forming a circuitous path, thereby delaying the pressure rise in the back pressure chamber.

2. The full-lift safety valve according to claim 1, characterized in that: The recoil disc area of ​​the valve disc assembly is 9.2 times the throat diameter area of ​​the safety valve.

3. The full-lift safety valve according to claim 1, characterized in that: The discharge outlet area of ​​the safety valve meets the following two conditions: it is greater than three times the throat diameter area of ​​the safety valve and greater than thirty times the total area of ​​the slot holes.

4. The full-lift safety valve according to claim 1, characterized in that: The performance parameters of the safety valve meet the following requirements: the opening and closing pressure difference ≤ the value of the excess pressure minus the return seat pressure, that is, the opening and closing pressure difference ≤ 5% of the set pressure, the return seat pressure ≥ 96% of the set pressure, and the discharge pressure ≤ 101% of the set pressure.

5. The full-lift safety valve according to claim 1, characterized in that: The guide back pressure base limits the opening height of the valve flap assembly to be greater than or equal to one quarter of the throat diameter of the safety valve.

6. A back pressure control method for a full lift safety valve according to any one of claims 1 to 5, characterized in that: include: Discharge stage: When the valve disc assembly presses against the guide back pressure base, the medium flows through the slot hole and changes the flow direction to form a circuitous path, blocking the medium from flowing into the back pressure chamber and delaying the pressure rise in the back pressure chamber; Reseating stage: When the system pressure is lower than the set pressure, the medium gradually flows into the back pressure chamber through the slot, causing the pressure in the back pressure chamber to slowly rise to the system pressure; the rising back pressure cooperates with the spring preload to act on the upper end of the valve disc assembly, driving the valve disc assembly to achieve sealing when the system pressure is greater than or equal to 96% of the set pressure.

7. The back pressure control method according to claim 6, characterized in that: In the reseating stage, when the pressure in the back pressure chamber rises to the system pressure, the back pressure and the spring preload force work together to make the valve disc assembly return to its seat and seal when the system pressure is greater than or equal to 96% of the set pressure.

8. A pressure vessel system, characterized in that: The fully-open safety valve according to any one of claims 1 to 5 is used for overpressure protection of gas manufacturing, storage or transportation equipment.

Images