Multi-cargo mixed LNG (Liquefied Natural Gas) pressure relief device

Abstract

The utility model discloses a multi-cargo mixed LNG (Liquefied Natural Gas) pressure relief device. Comprising a pilot valve; a main valve; the lower end of the vertical pipe is connected with a cabin, the upper end of the vertical pipe is connected with the bottom of the pilot valve, and the vertical pipe is communicated with a pilot valve cavity below the pilot valve element; one end of the top pipe is connected with the lower part of the pilot valve and is communicated with a pilot valve cavity below the pilot valve core; the other end of the main valve core is connected with the upper part of the main valve and is communicated with a main valve cavity above the main valve core; the top pipe is located below the pilot valve pressure relief opening. The bottom pipe is arranged below the top pipe, one end of the bottom pipe is connected with the bottom of the main valve, and the bottom pipe is communicated with a main valve cavity below the main valve element; the other end is communicated with the lower part of the vertical pipe; the blasting mechanism is arranged on the lower portion of the main valve element. The pressure relief device has the advantages that when the pilot valve breaks down and cannot normally relieve pressure, pressure relief can be conducted on a cabin, and the reliability of the pressure relief device is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of pressure relief device technology, and in particular to a pressure relief device for multi-cargo mixed LNG. Background Technology

[0002] With the global energy structure accelerating its transition to clean energy, liquefied natural gas (LNG), as a clean and efficient energy source, is playing an increasingly important role in international trade. Currently, LNG delivery and measurement mainly rely on calorific value calculations, which requires extremely precise analysis of the natural gas composition to ensure the fairness and accuracy of trade settlements. During voyages, LNG continuously evaporates in the ship's hold, with LNG evaporating into boil-off gas (BOG). When the ship's hold pressure reaches its maximum limit, a pilot-operated pressure relief valve is used to release pressure and maintain stability in the hold.

[0003] The existing pilot-operated pressure relief valve does not have an emergency valve port. If the pilot valve fails, the main valve will not be able to operate, thus losing its pressure relief function. Utility Model Content

[0004] The purpose of this utility model is to provide a multi-cargo mixed LNG depressurization device, which includes a pilot valve, a main valve, a vertical pipe, a top pipe, a bottom pipe, and a rupture mechanism. When the pilot valve malfunctions and cannot depressurize normally, causing the main valve plug to be unable to move upward, the rupture disc is squeezed and deformed, pressing against the cutter. The rupture disc is first pierced by the cone and then cut by the cutter. The evaporated gas in the cabin passes through the broken rupture disc, enters the vertical hole, and then enters the main valve depressurization port through the horizontal hole to be discharged, thus depressurizing the cabin and ensuring the reliability of the depressurization device.

[0005] To achieve the above objectives, the present invention adopts the following technical solution, including:

[0006] A pilot valve has an axially oriented pilot valve chamber inside; a pilot valve pressure relief port is radially arranged on the lower side wall of the pilot valve; an axially movable pilot valve core is provided inside the pilot valve chamber; a pilot valve spring is disposed inside the pilot valve chamber, with its upper end connected to the top wall of the pilot valve chamber and its lower end connected to the upper end of the pilot valve core; the pilot valve core is used to allow or prevent the pilot valve pressure relief port from communicating with the pilot valve chamber below the pilot valve core;

[0007] The main valve has an axially oriented main valve chamber inside; a main valve pressure relief port is radially arranged on the lower side wall of the main valve; an axially movable main valve core is arranged inside the main valve chamber; a main valve spring is arranged inside the main valve chamber, with its upper end connected to the top wall of the main valve chamber and its lower end connected to the upper end of the main valve core; the main valve core is used to allow or prevent the main valve pressure relief port from communicating with the main valve chamber below the main valve core;

[0008] The vertical pipe is connected to the cabin at its lower end and to the bottom of the pilot valve at its upper end, and communicates with the pilot valve cavity below the pilot valve core.

[0009] The jacking pipe has one end connected to the lower part of the pilot valve and communicates with the pilot valve cavity below the pilot valve core; the other end is connected to the upper part of the main valve and communicates with the main valve cavity above the main valve core; the jacking pipe is located below the pilot valve pressure relief port;

[0010] The bottom pipe is located below the top pipe, with one end connected to the bottom of the main valve and communicating with the main valve cavity below the main valve core; the other end is connected to the lower part of the vertical pipe.

[0011] The blasting mechanism is located at the lower part of the main valve core and is used to connect the main valve chamber below the main valve core with the main valve pressure relief port when the pilot valve fails.

[0012] Preferably, the pilot valve core includes:

[0013] A pilot valve plug is disposed at the lower part of the pilot valve core, and the outer periphery of the pilot valve plug is adapted to the inner periphery of the pilot valve cavity;

[0014] The pilot valve stem is located in the middle of the pilot valve core, and its lower end is connected to the pilot valve plug.

[0015] A pilot valve connecting plate is disposed on the upper part of the pilot valve core, with its lower end connected to the pilot valve stem and its upper end connected to the lower end of the pilot valve spring.

[0016] Preferably, the main valve core includes:

[0017] A main valve plug is disposed at the lower part of the main valve core, and the outer periphery of the main valve plug is adapted to the inner periphery of the main valve cavity;

[0018] The main valve stem is located in the middle of the main valve core, and its lower end is connected to the main valve plug.

[0019] The main valve connecting plate is located on the upper part of the main valve core, with its lower end connected to the main valve stem and its upper end connected to the lower end of the main valve spring.

[0020] Preferably, the blasting mechanism includes:

[0021] A horizontal hole is provided on the main valve plug for communicating with the main valve relief port.

[0022] A vertical hole is vertically and longitudinally disposed on the main valve plug, with its upper end connected to the horizontal hole and its lower end connected to the main valve cavity below the main valve core.

[0023] A rupture disc is disposed below the vertical hole; the rupture disc has a downwardly convex spherical structure;

[0024] Multiple cutting tools are radially evenly distributed within the rupture disc, and each cutting tool is provided with a conical spike for piercing the rupture disc.

[0025] Preferably, it also includes:

[0026] A retaining ring is disposed on the lower end face of the main valve plug, on the outer periphery of the vertical hole;

[0027] A connecting ring, coaxially disposed within the fixed ring, is used to cooperate with the fixed ring to clamp the edge of the rupture disc.

[0028] Preferably, it also includes:

[0029] A fixing block, which is evenly distributed around the outer periphery of the fixing ring;

[0030] Multiple reinforcing rings are coaxially arranged inside the connecting ring and connected to multiple cutting tools to reinforce the multiple cutting tools.

[0031] Preferably, a first limiting step is provided in the valve cavity of the pilot valve, and when the valve plug of the pilot valve abuts against the first limiting step, the pressure relief port of the pilot valve is fully opened.

[0032] Preferably, a second limiting step is provided in the main valve cavity, and when the main valve plug abuts against the second limiting step, the transverse hole is at least partially connected to the main valve pressure relief port.

[0033] Preferably, the cross-section of the transverse hole is vertically elliptical so that when the main valve plug is in any position within the main valve cavity, the transverse hole is at least partially connected to the main valve relief port, facilitating pressure relief.

[0034] The beneficial effects of this utility model are as follows: When the pilot valve malfunctions and cannot properly release pressure, causing the main valve plug to be unable to move upward, the rupture disc is squeezed and deformed, pressing against the cutter. The rupture disc is first pierced by the cone and then cut by the cutter. The evaporated gas in the cabin passes through the broken rupture disc, enters the vertical hole, and then enters the main valve pressure relief port through the horizontal hole to release pressure in the cabin, ensuring the reliability of the pressure relief device. Attached Figure Description

[0035] Figure 1 This is a perspective view of a multi-cargo mixed LNG depressurization device according to the present invention.

[0036] Figure 2 This is a three-dimensional sectional view of a multi-cargo mixed LNG depressurization device according to the present invention.

[0037] Figure 3 This is a perspective view of the main valve core in this utility model.

[0038] Figure 4 This is a three-dimensional sectional view of the main valve core in this utility model.

[0039] Figure 5 This is a perspective view of the blasting mechanism in this utility model.

[0040] Figure 6 This is a perspective view of the cutting tool in this utility model. Detailed Implementation

[0041] The utility model will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0042] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0043] like Figure 1-6 As shown, this utility model discloses a multi-cargo mixed LNG depressurization device, comprising:

[0044] A pilot valve 110 has an axially oriented pilot valve chamber 111 inside. A pilot valve pressure relief port 112 is radially arranged on the lower side wall of the pilot valve 110. An axially movable pilot valve core 113 is provided in the pilot valve chamber 111. A pilot valve spring 114 is disposed in the pilot valve chamber 111, with its upper end connected to the top wall of the pilot valve chamber 111 and its lower end connected to the upper end of the pilot valve core 113. The pilot valve core 113 is used to allow or prevent the pilot valve pressure relief port 112 from communicating with the pilot valve chamber 111 below the pilot valve core 113. As a preferred embodiment, the pilot valve core 113 includes: a pilot valve plug 113a, which is disposed at the lower part of the pilot valve core 113, and the outer periphery of the pilot valve plug 113a is adapted to the inner periphery of the pilot valve cavity 111; a pilot valve stem 113b, which is disposed at the middle part of the pilot valve core 113, and its lower end is connected to the pilot valve plug 113a; and a pilot valve connecting plate 113c, which is disposed at the upper part of the pilot valve core 113, with its lower end connected to the pilot valve stem 113b and its upper end connected to the lower end of the pilot valve spring 114. As a further preferred embodiment, a first limiting step 111a is provided in the pilot valve cavity 111, and when the pilot valve plug 113 abuts against the first limiting step 111a, the pilot valve pressure relief port 112 is fully opened.

[0045] The main valve 120 has an axial main valve chamber 121 inside; a main valve pressure relief port 122 is radially arranged on the lower side wall of the main valve 120; an axially movable main valve core 123 is provided in the main valve chamber 121; a main valve spring 124 is arranged in the main valve chamber 121, with its upper end connected to the top wall of the main valve chamber 121 and its lower end connected to the upper end of the main valve core 123; the main valve core 123 is used to allow or prevent the main valve pressure relief port 122 from communicating with the main valve chamber 121 below the main valve core 123. As a preferred embodiment, the main valve core 123 includes: a main valve plug 123a, disposed at the lower part of the main valve core 123, the outer periphery of the main valve plug 123a being adapted to the inner periphery of the main valve cavity 121; a main valve stem 123b, disposed at the middle part of the main valve core 123, the lower end of which is connected to the main valve plug 123a; and a main valve connecting plate 123c, disposed at the upper part of the main valve core 123, the lower end of which is connected to the main valve stem 123b, and the upper end of which is connected to the lower end of the main valve spring 124. As a further preferred embodiment, a second limiting step 121a is provided in the main valve cavity 121, such that when the main valve plug 123a abuts against the second limiting step 121a, the transverse hole 141 is at least partially connected to the main valve pressure relief port 122. As a further preferred embodiment, the cross-section of the transverse hole 141 is vertically elliptical so that when the main valve plug 123a is in any position within the main valve cavity 111, the transverse hole 141 is at least partially connected to the main valve pressure relief port 122, facilitating pressure relief.

[0046] A vertical pipe 131 is connected at its lower end to the hull and at its upper end to the bottom of the pilot valve 110, communicating with the pilot valve cavity 111 below the pilot valve core 113; a jacking pipe 132 is connected at one end to the lower part of the pilot valve 110 and communicates with the pilot valve cavity 111 below the pilot valve core 113; the other end is connected to the upper part of the main valve 120 and communicates with the main valve cavity 121 above the main valve core 123; the jacking pipe 132 is located below the pilot valve pressure relief port 112; a bottom pipe 133 is located below the jacking pipe 131, at one end to the bottom of the main valve 120 and communicates with the main valve cavity 121 below the main valve core 123; the other end is communicated with the lower part of the vertical pipe 131.

[0047] A rupture mechanism 140 is disposed below the main valve core 123 and is used to connect the main valve cavity 121 below the main valve core 123 with the main valve pressure relief port 122 when the pilot valve 110 fails. Preferably, a horizontal hole 141 is horizontally disposed on the main valve plug 123a and is used to connect with the main valve pressure relief port 122; a vertical hole 142 is vertically disposed on the main valve plug 123a, with its upper end connected to the horizontal hole 141 and its lower end connected to the main valve cavity 121 below the main valve core 123; a rupture disc 143 is disposed below the vertical hole 142; the rupture disc 143 has a downwardly convex spherical structure; multiple blades 144 are radially evenly distributed within the rupture disc 143, and each blade 144 is provided with a conical spike 145 for piercing the rupture disc 143. As a further preferred embodiment, it further includes: a retaining ring 146 disposed on the lower end face of the main valve plug 123a, on the outer periphery of the vertical hole 142; and a connecting ring 147 coaxially disposed within the retaining ring 146 for cooperating with the retaining ring 146 to clamp the edge of the rupture disc 143. As a further preferred embodiment, it further includes: a retaining block 148 evenly distributed circumferentially on the outer periphery of the retaining ring 146; and multiple reinforcing rings 149 coaxially disposed within the connecting ring 146 and connected to multiple cutting tools 144 for reinforcing the multiple cutting tools 144.

[0048] During use, the vertical pipe 131 is extended into the top of the cabin and sealed to prevent leakage. After the liquefied natural gas in the cabin evaporates, it forms boil-off gas (BOG). The boil-off gas enters the bottom pipe 133 and the pilot valve chamber 111 below the pilot valve core 113 through the vertical pipe 131. Then, it enters the main valve chamber 121 below the main valve core 123 through the bottom pipe 133. The boil-off gas in the pilot valve chamber 111 below the pilot valve core 113 enters the main valve chamber 121 above the main valve core 123 through the top pipe 132. When the pressure of the vaporized gas in the cabin is less than the design value, the thrust of the vaporized gas on the pilot valve core 113 is less than the thrust of the pilot valve spring 114. The pilot valve core 113 moves down, blocking the pilot valve pressure relief port 112. There is no vaporized gas leakage at the pilot valve 110. The pressure in the main valve chamber 121 below the main valve core 123 and the main valve chamber 121 above the main valve core 123 is equal. The main valve spring 124 extends, pushing the main valve plug 123a down, blocking the main valve pressure relief port 122. There is no vaporized gas leakage at the main valve 120.

[0049] When the pressure of the evaporated gas inside the cabin exceeds the design value, the thrust of the evaporated gas on the pilot valve core 113 is greater than the thrust of the pilot valve spring 114. The pilot valve core 113 moves upward, away from the pilot valve relief port 112. The evaporated gas in the pilot valve chamber 111 below the pilot valve core 113 is discharged from the pilot valve relief port 112. The steam in the pilot valve chamber 111 below the pilot valve core 113 decreases. The evaporated gas in the main valve chamber 121 above the main valve core 123 flows from the top pipe 132 into the pilot valve chamber 111 below the pilot valve core 113, and then is discharged through the pilot valve relief port 112. The main valve chamber above the main valve core 123... When the pressure inside valve 121 is lower than the pressure inside the main valve chamber 121 below the main valve core 123, the main valve spring 124 contracts, and the main valve plug 123a moves upward, away from the main valve pressure relief port 122. The evaporated gas in the main valve chamber 121 below the main valve core 123 is discharged from the main valve pressure relief port 122, depressurizing the cabin until the pressure drops below the design value. Then, the pilot valve spring 114 and the main valve spring 124 reset, pushing the pilot valve core 113 and the main valve plug 123a downward respectively. The pilot valve core 113 blocks the pilot valve pressure relief port 112, and the main valve plug 123a blocks the main valve pressure relief port 122, thus closing the pressure relief device.

[0050] When the pilot valve 110 malfunctions and cannot release pressure normally, the pressure in the main valve chamber 121 above the main valve core 123 is always equal to the pressure in the main valve chamber 121 below the main valve core 123. The main valve plug 123a cannot move upward and cannot release pressure in the cabin. When the pressure in the cabin is higher than a certain design value, the rupture disc 143 is squeezed and deformed, pressing against the cutter 144. The rupture disc 143 is first pierced by the cone 145 and then cut by the cutter 144. The vaporized gas in the cabin passes through the broken rupture disc 143, enters the vertical hole 142, and then enters the main valve pressure relief port 122 through the horizontal hole 141 to be discharged, thus releasing pressure in the cabin.

[0051] In another embodiment, the pilot valve core 113 includes: a pilot valve plug 113a, which is disposed at the lower part of the pilot valve core 113, the outer periphery of the pilot valve plug 113a being adapted to the inner periphery of the pilot valve cavity 111; a pilot valve stem 113b, which is disposed at the middle part of the pilot valve core 113, with its lower end connected to the pilot valve plug 113a; and a pilot valve connecting plate 113c, which is disposed at the upper part of the pilot valve core 113, with its lower end connected to the pilot valve stem 113b and its upper end connected to the lower end of the pilot valve spring 114.

[0052] In another embodiment, the main valve core 123 includes: a main valve plug 123a disposed at the lower part of the main valve core 123, the outer periphery of the main valve plug 123a being adapted to the inner periphery of the main valve cavity 121; a main valve stem 123b disposed at the middle part of the main valve core 123, the lower end of which is connected to the main valve plug 123a; and a main valve connecting plate 123c disposed at the upper part of the main valve core 123, the lower end of which is connected to the main valve stem 123b, and the upper end of which is connected to the lower end of the main valve spring 124.

[0053] In another embodiment, the blasting mechanism 140 includes: a horizontal hole 141, which is horizontally disposed on the main valve plug 123a for communicating with the main valve pressure relief port 122; a vertical hole 142, which is vertically disposed on the main valve plug 123a, with its upper end communicating with the horizontal hole 141 and its lower end communicating with the main valve cavity 121 below the main valve core 123; a rupture disc 143, which is disposed below the vertical hole 142; the rupture disc 143 has a downwardly convex spherical structure; and multiple blades 144, which are radially evenly distributed within the rupture disc 143, with conical spikes 145 on the blades 144 for piercing the rupture disc 143.

[0054] In another embodiment, it further includes: a retaining ring 146 disposed on the lower end face of the main valve plug 123a, on the outer periphery of the vertical hole 142; and a connecting ring 147 coaxially disposed within the retaining ring 146 for cooperating with the retaining ring 146 to clamp the edge of the rupture disc 143.

[0055] In another embodiment, it further includes: a fixing block 148, which is evenly distributed around the outer periphery of the fixing ring 146; and multiple reinforcing rings 149, which are coaxially disposed within the connecting ring 146 and connected to multiple cutting tools 144 respectively, for reinforcing the multiple cutting tools 144.

[0056] In another embodiment, a first limiting step 111a is provided in the pilot valve cavity 111. When the pilot valve plug 113 abuts against the first limiting step 111a, the pilot valve pressure relief port 112 is fully opened.

[0057] In another embodiment, a second limiting step 121a is provided in the main valve cavity 121. When the main valve plug 123a abuts against the second limiting step 121a, the transverse hole 141 is at least partially connected to the main valve pressure relief port 122.

[0058] In another embodiment, the cross-section of the transverse hole 141 is vertically elliptical so that when the main valve plug 123a is in any position within the main valve cavity 111, the transverse hole 141 is at least partially connected to the main valve pressure relief port 122 to facilitate pressure relief.

[0059] In summary, this utility model provides a multi-cargo mixed LNG depressurization device, comprising a pilot valve, a main valve, a vertical pipe, a top pipe, a bottom pipe, and a rupture mechanism. When the pilot valve malfunctions and cannot depressurize normally, causing the main valve plug to be unable to move upward, the rupture disc is squeezed and deformed, pressing against the cutting tool. The rupture disc is first pierced by a cone and then cut by the cutting tool. The evaporated gas in the cabin passes through the broken rupture disc, enters the vertical hole, and then enters the main valve depressurization port through the horizontal hole to be discharged, thus depressurizing the cabin and ensuring the reliability of the depressurization device.

[0060] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A multi-cargo mixed LNG pressure relief device, characterized by, The application relates to a valve device for a ship's ballast tank. The pilot valve is internally provided with an axial pilot valve cavity; a pilot valve pressure relief port is radially arranged on the side wall of the lower part of the pilot valve; an axially movable pilot valve spool is arranged in the pilot valve cavity; a pilot valve spring is arranged in the pilot valve cavity, the upper end of the pilot valve spring is connected with the top wall of the pilot valve cavity, and the lower end of the pilot valve spring is connected with the upper end of the pilot valve spool; the pilot valve spool is used for allowing or preventing the pilot valve pressure relief port from being communicated with the pilot valve cavity below the pilot valve spool; The main valve is internally provided with an axial main valve cavity; a main valve pressure relief port is radially arranged on the side wall of the lower part of the main valve; an axially movable main valve spool is arranged in the main valve cavity; a main valve spring is arranged in the main valve cavity, the upper end of the main valve spring is connected with the top wall of the main valve cavity, and the lower end of the main valve spring is connected with the upper end of the main valve spool; the main valve spool is used for allowing or preventing the main valve pressure relief port from being communicated with the main valve cavity below the main valve spool; The vertical pipe is connected with the cabin at the lower end and connected with the bottom of the pilot valve at the upper end, and is communicated with the pilot valve cavity below the pilot valve spool; The top pipe is connected with the lower part of the pilot valve at one end and communicated with the pilot valve cavity below the pilot valve spool; the other end is connected with the upper part of the main valve and communicated with the main valve cavity above the main valve spool; the top pipe is located below the pilot valve pressure relief port; The bottom pipe is arranged below the top pipe, connected with the bottom of the main valve at one end and communicated with the main valve cavity below the main valve spool; the other end is communicated with the lower part of the vertical pipe; The bursting mechanism is arranged at the lower part of the main valve spool and used for communicating the main valve cavity below the main valve spool with the main valve pressure relief port when the pilot valve fails.

2. The multi-fuel hybrid LNG pressure relief device of claim 1, wherein, The pilot valve spool comprises: The pilot valve plug is arranged at the lower part of the pilot valve spool, and the outer periphery of the pilot valve plug is matched with the inner periphery of the pilot valve cavity; The pilot valve stem is arranged at the middle part of the pilot valve spool, and the lower end of the pilot valve stem is connected with the pilot valve plug; The pilot valve connecting plate is arranged at the upper part of the pilot valve spool, the lower end of the pilot valve connecting plate is connected with the pilot valve stem, and the upper end of the pilot valve connecting plate is connected with the lower end of the pilot valve spring.

3. The multi-fuel hybrid LNG pressure relief device of claim 2, wherein, The main valve spool comprises: The main valve plug is arranged at the lower part of the main valve spool, and the outer periphery of the main valve plug is matched with the inner periphery of the main valve cavity; The main valve stem is arranged at the middle part of the main valve spool, and the lower end of the main valve stem is connected with the main valve plug; The main valve connecting plate is arranged at the upper part of the main valve spool, the lower end of the main valve connecting plate is connected with the main valve stem, and the upper end of the main valve connecting plate is connected with the lower end of the main valve spring.

4. The multi-fuel hybrid LNG pressure relief device of claim 3, wherein, The bursting mechanism comprises: The horizontal hole is horizontally arranged on the main valve plug and used for being communicated with the main valve pressure relief port; The vertical hole is vertically arranged on the main valve plug, the upper end of the vertical hole is communicated with the horizontal hole, and the lower end of the vertical hole is communicated with the main valve cavity below the main valve spool; The bursting disc is arranged below the vertical hole; the bursting disc has a downwardly protruding spherical surface structure; A plurality of cutters are radially arranged in the bursting disc, and the cutters are provided with tapered spikes for piercing the bursting disc.

5. The multi-fuel hybrid LNG pressure relief device of claim 4, wherein, Further, the application also relates to a fixed ring arranged on the lower end surface of the main valve plug and the outer periphery of the vertical hole. ​ A connecting ring coaxially arranged in the fixed ring is used to hold the edge of the rupture disc in cooperation with the fixed ring.

6. The multi-fuel hybrid LNG pressure relief device of claim 5, wherein, Further comprising: A fixed block is arranged on the outer periphery of the fixed ring along the circumference; A plurality of reinforcing rings are coaxially arranged in the connecting ring respectively and connected with a plurality of cutters respectively, used to reinforce the plurality of cutters.

7. The multi-fuel hybrid LNG pressure relief device of claim 4, wherein: A first limiting step is arranged in the pilot valve chamber, when the pilot valve plug abuts against the first limiting step, all the pilot valve relief ports are opened.

8. The multi-fuel hybrid LNG pressure relief device of claim 4, wherein: A second limiting step is arranged in the main valve chamber, when the main valve plug abuts against the second limiting step, the transverse hole and the main valve relief port are at least partially communicated.

9. The multi-fuel hybrid LNG pressure relief device of claim 4, wherein: The transverse hole is vertically elliptical in cross section, so that when the main valve plug is at any position in the main valve chamber, the transverse hole and the main valve relief port are at least partially communicated, facilitating pressure relief.

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