A back pressure device suitable for gas and supercritical fluid

Abstract

The present invention relates to the technical field of back pressure devices, and discloses a back pressure device suitable for gas and supercritical fluid, which includes: a pneumatic valve, a first tank body, a first sealing piston, a second tank body, a second sealing piston, a first liquid path, a second liquid path, a first back pressure valve, and a second back pressure valve. The present invention switches between a first state and a second state so that the gas introduced into the pneumatic valve flows into the first gas chamber or the second gas chamber to increase the pressure, thereby driving the first sealing piston or the second sealing piston to move. When the liquid circulates, the first gas chamber and the second gas chamber are exhausted and pressure-released in turn. The present invention uses a liquid with a larger viscosity to replace a gas or supercritical fluid with a smaller viscosity to enter the first back pressure valve and the second back pressure valve, thereby avoiding the phenomenon of a large amount of gas or supercritical fluid flowing out in a short time, thereby enhancing the stability of the air pressure in the external pipeline, which is conducive to maintaining a constant pressure difference in the external pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of back pressure devices, and in particular to a back pressure device suitable for gas and supercritical fluid. Background Art

[0002] Back-pressure valves are commonly used in rock engineering to maintain fluid pressure within pipelines. They typically stabilize flow, prevent backflow, and protect equipment. In practice, when the gas pressure within the pipeline exceeds the valve's preset pressure, the low viscosity of the gas or supercritical fluid causes a large outflow of the gas or supercritical fluid from the valve within a short period of time. This causes significant pressure fluctuations within the pipeline, making it impossible for the valve to maintain a constant pressure differential.

[0003] Therefore existing technology still needs to be improved and improved. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a back pressure device suitable for gas and supercritical fluid, which aims to solve the problem in the prior art that when the gas pressure in the pipeline exceeds the predetermined pressure of the back pressure valve, due to the low viscosity of the gas or supercritical fluid, a large amount of gas or supercritical fluid will flow out of the back pressure valve in a short period of time, resulting in large pressure fluctuations in the pipeline and the back pressure valve cannot maintain a constant pressure difference in the pipeline.

[0005] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0006] In a first aspect, an embodiment of the present invention provides a back pressure device applicable to gas and supercritical fluid, comprising:

[0007] A pneumatic valve, wherein one end of the pneumatic valve is provided with a first valve and a second valve, and the other end is used to connect to an external pipeline to introduce gas;

[0008] a first tank body, wherein a first sealing piston is disposed in the first tank body, the first sealing piston being used to separate the first tank body into a first gas chamber and a first liquid chamber, the first gas chamber being provided with a first pressure relief port, and the first gas chamber being in communication with the first valve;

[0009] a second tank body, wherein a second sealing piston is provided in the second tank body, the second sealing piston is used to separate the second tank body into a second gas chamber and a second liquid chamber, the second gas chamber is provided with a second pressure relief port, and the second gas chamber is connected to the second valve;

[0010] A first liquid path and a second liquid path are provided between the first liquid chamber and the second liquid chamber to form a liquid circulation loop. A first back-pressure valve is provided on the first liquid path, and a second back-pressure valve is provided on the second liquid path. The pressures in the first back-pressure valve and the second back-pressure valve are consistent with the predetermined pressure in the external pipeline. The maximum capacities of the first liquid chamber and the second liquid chamber are consistent.

[0011] The back pressure device suitable for gas and supercritical fluid has a first state and a second state. When it is in the first state, the first pressure relief port is closed, the second pressure relief port is opened, the first valve is opened, and the second valve is closed. When it is in the second state, the first pressure relief port is opened, the second pressure relief port is closed, the first valve is closed, and the second valve is opened.

[0012] As a further improved technical solution, the above-mentioned back pressure device applicable to gas and supercritical fluid further includes:

[0013] a first sensor disposed on a side of the first gas chamber opposite to the first sealing piston;

[0014] a second sensor disposed on a side of the second gas chamber opposite to the second sealing piston;

[0015] a third sensor, the third sensor being disposed at the first valve;

[0016] When the first sensor senses the first sealing piston and the pressure reaches the predetermined pressure, the first valve opens and the second valve closes; when the third sensor senses the first valve opening, the first pressure relief port closes and the second pressure relief port opens;

[0017] When the second sensor senses the second sealing piston and the pressure reaches the predetermined pressure, the first valve closes and the second valve opens; when the third sensor senses that the first valve is closed, the first pressure relief port opens and the second pressure relief port closes.

[0018] As a further improved technical solution, a first electric needle valve is provided at the first pressure relief port to control its opening or closing.

[0019] As a further improved technical solution, a second electric needle valve is provided at the second pressure relief port to control its opening or closing.

[0020] As a further improved technical solution, the above-mentioned back pressure device applicable to gas and supercritical fluid further includes:

[0021] a first air pipe, one end of which is connected to the first air valve, a first air injection hole is provided on the first gas chamber, and the other end of the first air pipe is connected to the first air injection hole;

[0022] A second air pipe, one end of the second air pipe is connected to the second air valve, a second air injection hole is provided on the second gas chamber, and the other end of the second air pipe is connected to the second air injection hole.

[0023] As a further improved technical solution, the above-mentioned back pressure device applicable to gas and supercritical fluid further includes:

[0024] An air circuit one-way valve is provided, wherein the first air pipe and the second air pipe are respectively connected to the air circuit one-way valve.

[0025] As a further improved technical solution, the first liquid chamber is provided with a first liquid discharge hole and a first liquid inlet hole, and the second liquid chamber is provided with a second liquid discharge hole and a second liquid inlet hole;

[0026] The first liquid circuit includes a first liquid pipe and a second liquid pipe, the two ends of the first liquid pipe are respectively connected to the first liquid discharge hole and the first back pressure valve, and the two ends of the second liquid pipe are respectively connected to the first back pressure valve and the second liquid inlet hole;

[0027] The second liquid circuit includes a third liquid pipe and a fourth liquid pipe. Both ends of the third liquid pipe are connected to the second liquid discharge hole and the second back pressure valve respectively. Both ends of the fourth liquid pipe are connected to the second back pressure valve and the first liquid inlet hole respectively.

[0028] As a further improved technical solution, the above-mentioned back pressure device applicable to gas and supercritical fluid further includes:

[0029] Liquid circuit one-way valves are respectively provided on the first liquid pipe, the second liquid pipe, the third liquid pipe and the fourth liquid pipe.

[0030] As a further improved technical solution, the above-mentioned back pressure device applicable to gas and supercritical fluid further includes:

[0031] The third tank body and the fifth liquid pipe, the top side of the third tank body is provided with a third liquid inlet hole, the bottom side of the third tank body is provided with a third liquid discharge hole, the two ends of the third liquid pipe are respectively connected to the second liquid discharge hole and the third liquid inlet hole, and the two ends of the fifth liquid pipe are respectively connected to the third liquid discharge hole and the second back pressure valve.

[0032] As a further improved technical solution, a liquid injection hole is further provided on the top side of the third tank body.

[0033] Compared with the prior art, the embodiments of the present invention have the following advantages: in the present invention, the back pressure device needs to be filled with liquid in the first liquid chamber, the first liquid circuit, and the second liquid circuit before use, and the hydraulic pressure in the first liquid chamber or the second liquid chamber after being filled with liquid is consistent with the predetermined pressure in the external pipeline; when the present invention is configured so that the first liquid chamber reaches the maximum capacity and the hydraulic pressure in the first liquid chamber reaches the predetermined pressure, the first state is operated; when the present invention is configured so that the second liquid chamber reaches the maximum capacity and the hydraulic pressure in the second liquid chamber reaches the predetermined pressure, the second state is operated. By switching between the first state and the second state, the gas introduced by the pneumatic valve flows into the first gas chamber or the second gas chamber to increase the pressure to drive the first sealing piston or the second sealing piston to move, so that the first gas chamber and the second gas chamber are exhausted and depressurized in turn during the continuous circulation of the liquid. In addition, the present invention uses a liquid with a higher viscosity to replace the gas or supercritical fluid with a lower viscosity to enter the first back-pressure valve and the second back-pressure valve, which can avoid the phenomenon of gas or supercritical fluid flowing out of the first back-pressure valve or the second back-pressure valve in a large amount in a short time at the first back-pressure valve or the second back-pressure valve, thereby enhancing the stability of the air pressure in the external pipeline and facilitating the maintenance of a constant pressure difference in the external pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic structural diagram of a first embodiment of a back pressure device applicable to gas and supercritical fluid provided by the present invention;

[0035] Figure 2 This is a schematic structural diagram of a second embodiment of a back pressure device suitable for gas and supercritical fluid provided by the present invention.

[0036] In the figure: 1, pneumatic valve; 101, first air valve; 102, second air valve; 2, first tank body; 201, first gas chamber; 2011, first pressure relief port; 2012, first air injection hole; 202, first liquid chamber; 2021, first liquid discharge hole; 2022, first liquid inlet hole; 3, first sealing piston; 4, second tank body; 401, second gas chamber; 4011, second pressure relief port; 4012, second air injection hole; 402, second liquid chamber; 4021, second liquid discharge hole; 4022, second liquid inlet hole; 5, second sealing piston; 6, first back pressure valve; 7 , second back pressure valve; 8, first sensor; 9, second sensor; 10, first electric needle valve; 11, second electric needle valve; 12, third sensor; 13, first air pipe; 14, second air pipe; 15, air circuit one-way valve; 16, first liquid pipe; 17, second liquid pipe; 18, third liquid pipe; 19, fourth liquid pipe; 20, liquid circuit one-way valve; 21, third tank body; 2101, third liquid discharge hole; 2102, third liquid inlet hole; 2103, liquid injection hole; 22, fifth liquid pipe; 23, block; 24, back pressure pump; 25, tee; 26, sixth liquid pipe; 27, seventh liquid pipe. DETAILED DESCRIPTION

[0037] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0038] Example

[0039] See also Figure 1 and Figure 2. Wherein, the back pressure device suitable for gas and supercritical fluid includes: a pneumatic valve 1, one end of the pneumatic valve 1 is provided with a first valve 101 and a second valve 102, and the other end is used to connect to an external pipeline to introduce gas; a first tank body 2, a first sealing piston 3 is provided in the first tank body 2, the first sealing piston 3 is used to separate the first tank body 2 into a first gas chamber 201 and a first liquid chamber 202, the first gas chamber 201 is provided with a first pressure relief port 2011, and the first gas chamber 201 is connected to the first valve 101; a second tank body 4, a second sealing piston 5 is provided in the second tank body 4, the second sealing piston 5 is used to separate the second tank body 4 into a second gas chamber 401 and a second liquid chamber 402, the second gas chamber 401 is provided with a second pressure relief port 4011, and the second gas chamber 401 is connected to the second valve 102 Pass; a first liquid path and a second liquid path are provided between the first liquid chamber 202 and the second liquid chamber 402 to form a liquid circulation loop, a first back pressure valve 6 is provided on the first liquid path, and a second back pressure valve 7 is provided on the second liquid path, the pressures in the first back pressure valve 6 and the second back pressure valve 7 are consistent with the predetermined pressure in the external pipeline, and the maximum capacity of the first liquid chamber 202 and the second liquid chamber 402 are consistent; the back pressure device suitable for gas and supercritical fluid has a first state and a second state, when it is in the first state, the first pressure relief port 2011 is closed, the second pressure relief port 4011 is opened, the first valve 101 is opened, and the second valve 102 is closed, and when it is in the second state, the first pressure relief port 2011 is opened, the second pressure relief port 4011 is closed, the first valve 101 is closed, and the second valve 102 is opened.

[0040] Specifically, if Figure 1Described, the top end of the pneumatic valve 1 is provided with an external pipeline for connecting the need to maintain a stable air pressure in the pipe, and the bottom end of the pneumatic valve 1 is provided with a first valve 101 and a second valve 102. When one of the first valve 101 and the second valve 102 is opened, the other is in a closed state. A movable first sealing piston 3 is provided in the first tank body 2, and the side periphery of the first sealing piston 3 is pressed against the inner wall of the first tank body 2 to achieve sealing, and the first sealing piston 3 can move up and down in the first tank body 2. The first sealing piston 3 divides the interior of the first tank body 2 into a first gas chamber 201 and a first liquid chamber 202. The first gas chamber 201 is provided with a first pressure relief port 2011, and the first gas chamber 201 is communicated with the first valve 101. The gas in the external pipeline can be transported to the first gas chamber 201 through the first valve 101; a movable second sealing piston 5 is provided in the second tank body 4. The side circumference of the second sealing piston 5 is pressed against the inner wall of the second tank body 4 to achieve sealing, and the second sealing piston 5 can move up and down in the second tank body 4. The second sealing piston 5 divides the interior of the second tank body 4 into a second gas chamber 401 and a second liquid chamber 402. The second gas chamber 401 is provided with a second pressure relief port 4011, and the second gas chamber 401 is connected to the second valve 102. The gas in the external pipeline can be transported to the second gas chamber 401 through the second valve 102; a first liquid path and a second liquid path are provided between the first liquid chamber 202 and the second liquid chamber 402 to form a liquid circulation loop, the first liquid path is used to transport the liquid in the first liquid chamber 202 to the second liquid chamber 402 through the first back pressure valve 6, and the second liquid path is used to transport the liquid in the second liquid chamber 402 to the first liquid chamber 202 through the second back pressure valve 7 to achieve the circulation of the liquid. Among them, the pressure in the first back pressure valve 6 and the second back pressure valve 7 are consistent with the predetermined pressure in the external pipeline, so that the first sealing piston 3 or the second sealing piston 5 can be pushed to move only when the air pressure in the first gas chamber 201 or the second gas chamber 401 is greater than the predetermined pressure; the maximum capacity and maximum discharge volume of the first liquid chamber 202 and the second liquid chamber 402 are consistent to avoid hydraulic imbalance caused by inconsistent discharge volume between the first tank body 2 and the second tank body 4 when the liquid circulates; when the back pressure device suitable for gas and supercritical fluid is configured so that the first liquid chamber 202 reaches the maximum capacity and the hydraulic pressure in the first liquid chamber 202 reaches the predetermined pressure, the first state is operated; when the back pressure device suitable for gas and supercritical fluid is configured so that the second liquid chamber 402 reaches the maximum capacity and the hydraulic pressure in the second liquid chamber 402 reaches the predetermined pressure, the second state is operated.

[0041] When the pneumatic valve 1 continuously takes in air, the first state and the second state continuously switch and operate. By switching between the first state and the second state, the gas introduced by the pneumatic valve 1 flows into the first gas chamber 201 or the second gas chamber 401 to increase the pressure to drive the first sealing piston 3 or the second sealing piston 5 to move, so that the first gas chamber 201 and the second gas chamber 401 can be exhausted and depressurized in turn during the continuous circulation of the liquid. In addition, the present invention uses a liquid with a higher viscosity to replace the gas or supercritical fluid with a lower viscosity to enter the first back-pressure valve 6 and the second back-pressure valve 7, which can avoid the phenomenon of gas or supercritical fluid flowing out of the first back-pressure valve 6 or the second back-pressure valve 7 in a large amount in a short time at the first back-pressure valve 6 or the second back-pressure valve 7, thereby enhancing the stability of the air pressure in the external pipeline, which is conducive to maintaining a constant pressure difference in the external pipeline.

[0042] The principle of the back pressure device in this embodiment is as follows:

[0043] First, before using the back pressure device, it is necessary to fill the first liquid circuit, the second liquid circuit, and the first liquid chamber 202 with liquid, and the liquid is incompatible with the gas in the external pipeline. Then, the pressure in the first back pressure valve 6 and the second back pressure valve 7 is maintained at a predetermined pressure. For example, if the predetermined pressure in the external pipeline is 8MPa, the pressure in the first back pressure valve 6 and the second back pressure valve 7 is always maintained at 8MPa. When the first liquid chamber 202 is filled with liquid or the second liquid chamber 402 is filled with liquid, the hydraulic pressure is 8MPa. Initially, only the first liquid chamber 202 is filled with liquid, and the second liquid chamber 402 is empty. In the initial state, the back pressure device suitable for gas and supercritical fluid is configured so that the first liquid chamber 202 reaches the maximum capacity and the hydraulic pressure in the first liquid chamber 202 reaches the predetermined pressure of the external pipeline 8MPa. At this time, the first state is operated: the first pressure relief port 2011 is closed, the second pressure relief port 4011 is opened, the first valve 101 is opened, the second valve 102 is closed, and the gas in the external pipeline is injected into the first gas chamber 201. At this time, the gas pressure in the first gas chamber 201 increases and the second pressure relief port 4011 that is opened cooperates with the first sealing piston 3 to push downward. The first sealing piston 3 gradually discharges the liquid in the first liquid chamber 202 into the second liquid chamber 402. When the first liquid chamber When the first sealing piston 3 in 202 stops advancing, the back pressure device suitable for gas and supercritical fluid is configured so that when the second liquid chamber 402 reaches the maximum capacity and the hydraulic pressure in the second liquid chamber 402 reaches the predetermined pressure, the second state is operated at this time, that is, the first pressure relief port 2011 is opened, the second pressure relief port 4011 is closed, and the first valve 101 is closed, the second valve 102 is opened, and the gas in the second valve 102 pushes the second sealing piston 5, so that the liquid in the second liquid chamber 402 is recirculated into the first liquid chamber 202. This process realizes both gas pressure relief and liquid circulation, so that the back pressure device can continuously exhaust and relieve pressure and the liquid can continue to circulate.

[0044] Furthermore, the back pressure device applicable to gas and supercritical fluid further includes:

[0045] A first sensor 8, the first sensor 8 is arranged on the side of the first gas chamber 201 opposite to the first sealing piston 3; a second sensor 9, the second sensor 9 is arranged on the side of the second gas chamber 401 opposite to the second sealing piston 5; a third sensor 12, the third sensor 12 is arranged at the first valve 101; when the first sensor 8 senses the first sealing piston 3 and the pressure reaches the predetermined pressure, the first valve 101 opens and the second valve 102 closes, when the third sensor 12 senses that the first valve 101 is open, the first pressure relief port 2011 is closed and the second pressure relief port 4011 is opened; when the second sensor 9 senses the second sealing piston 5 and the pressure reaches the predetermined pressure, the first valve 101 is closed and the second valve 102 is opened, when the third sensor 12 senses that the first valve 101 is closed, the first pressure relief port 2011 is opened and the second pressure relief port 4011 is closed. That is, in this embodiment, the first sensor 8 and the second sensor 9 are used to control the switching opening and closing of the first valve 101 and the second valve 102, and the third sensor 12 is used to control the switching opening and closing of the first pressure relief port 2011 and the second pressure relief port 4011. By setting the third sensor 12 at the first valve 101, the first pressure relief port 2011 or the second pressure relief port 4011 can be opened in advance in time, so that the advancement of the first sealing piston 3 and the second sealing piston 5 is smoother.

[0046] The first sensor 8 and the second sensor 9 can both be existing piezoresistive pressure sensors or piezoelectric pressure sensors, while the third sensor 12 is a displacement sensor for detecting the displacement of the first valve 101. This embodiment also includes a control module (not shown), to which the first sensor 8, the second sensor 9, the third sensor 12, and the pneumatic valve 1 are respectively connected.

[0047] Furthermore, a first electric needle valve 10 is provided at the first pressure relief port 2011 to control its opening or closing, and a second electric needle valve 11 is provided at the second pressure relief port 4011 to control its opening or closing. Specifically, the first electric needle valve 10 and the second electric needle valve 11 are each electrically connected to a control module to control the opening or closing of the first pressure relief port 2011 and the second pressure relief port 4011.

[0048] In this embodiment, the back pressure device suitable for gas and supercritical fluid also includes: a first air pipe 13, one end of the first air pipe 13 is connected to the first air valve 101, a first air injection hole 2012 is provided on the first gas chamber 201, and the other end of the first air pipe 13 is connected to the first air injection hole 2012; a second air pipe 14, one end of the second air pipe 14 is connected to the second air valve 102, a second air injection hole 4012 is provided on the second gas chamber 401, and the other end of the second air pipe 14 is connected to the second air injection hole 4012.

[0049] Furthermore, the back pressure device for gas and supercritical fluid further includes a gas circuit check valve 15, which is connected to the first gas pipe 13 and the second gas pipe 14. The gas circuit check valve 15 ensures that gas flows only from the gas inlet to the gas outlet of the valve body, preventing gas backflow and ensuring that the gas pressure in the first gas chamber 201 and the second gas chamber 401 continues to increase.

[0050] Furthermore, the first liquid chamber 202 is provided with a first liquid drainage hole 2021 and a first liquid inlet hole 2022, and the second liquid chamber 402 is provided with a second liquid drainage hole 4021 and a second liquid inlet hole 4022; the first liquid circuit includes a first liquid pipe 16 and a second liquid pipe 17, and the two ends of the first liquid pipe 16 are respectively connected to the first liquid drainage hole 2021 and the first back pressure valve 6, and the two ends of the second liquid pipe 17 are respectively connected to the first back pressure valve 6 and the second liquid inlet hole 4022; the second liquid circuit includes a third liquid pipe 18 and a fourth liquid pipe 19, and the two ends of the third liquid pipe 18 are respectively connected to the second liquid drainage hole 4021 and the second back pressure valve 7, and the two ends of the fourth liquid pipe 19 are respectively connected to the second back pressure valve 7 and the first liquid inlet hole 2022.

[0051] In this embodiment, the back pressure device applicable to gases and supercritical fluids further includes a liquid check valve 20, which is provided on each of the first liquid pipe 16, the second liquid pipe 17, the third liquid pipe 18, and the fourth liquid pipe 19. The liquid check valve 20 ensures that liquid flows only from the liquid inlet to the liquid outlet of the valve body, preventing liquid backflow and ensuring that the hydraulic pressure in the first liquid chamber 202 and the second liquid chamber 402 reaches a predetermined pressure.

[0052] like Figure 2As shown, further, the back pressure device suitable for gas and supercritical fluid also includes a third tank body 21 and a fifth liquid pipe 22. The top side of the third tank body 21 is provided with a third liquid inlet hole 2102, and the bottom side of the third tank body 21 is provided with a third liquid discharge hole 2101. The two ends of the third liquid pipe 18 are respectively connected to the second liquid discharge hole 4021 and the third liquid inlet hole 2102, and the two ends of the fifth liquid pipe 22 are respectively connected to the third liquid discharge hole 2101 and the second back pressure valve 7. Specifically, in the initial stage of the back pressure device, it is necessary to fill the third tank body 21 and the fifth liquid pipe 22 with liquid. After the third tank body 21 and the fifth liquid pipe 22 are filled with liquid, the hydraulic pressure inside them is consistent with the predetermined pressure in the external pipeline. For example, if the predetermined gas pressure in the external pipeline is 8 MPa, the hydraulic pressure in the third tank body 21 and the fifth liquid pipe 22 is 8 MPa. The third tank body 21 in the back pressure device can buffer the flow of liquid between the first liquid chamber 202 and the second liquid chamber 402. By providing the third tank body 21 filled with liquid, the liquid circulation loop can significantly improve stability, safety and reliability, especially in high-pressure, high-temperature and high-precision scenarios.

[0053] Furthermore, a liquid injection hole 2103 is further provided on the top side of the third tank body 21 , through which liquid can be injected into the first liquid chamber 202 , the first liquid path, the second liquid path and the third tank body 21 .

[0054] In this embodiment, the back pressure device suitable for gas and supercritical fluid also includes a back pressure pump 24, a tee 25, a sixth liquid pipe 26 and a seventh liquid pipe 27. The two ends of the sixth liquid pipe 26 are respectively connected to the tee 25 and the first back pressure valve 6, and the two ends of the seventh liquid pipe 27 are respectively connected to the tee 25 and the second back pressure valve 7. The tee 25 is connected to the back pressure pump 24 through a pipeline, and the first back pressure valve 6 and the second back pressure valve 7 maintain the internal pressure through the back pressure pump 24.

[0055] Furthermore, a stopper 23 is provided on the side of the first liquid chamber 202 opposite to the first sealing piston 3 and on the side of the second liquid chamber 402 opposite to the second sealing piston 5 to prevent the first sealing piston 3 and the second sealing piston 5 from being adsorbed by the liquid, thereby promoting the timely circulation of the liquid.

[0056] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0058] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0059] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0060] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0061] Of course, the description of the above embodiments of the present invention is relatively detailed, but it cannot be understood as limiting the scope of protection of the present invention. The present invention can also have many other implementation methods. Based on this implementation method, other implementation methods obtained by ordinary technicians in this field without making any creative work are all within the scope of protection of the present invention. The scope of protection of the present invention shall be based on the attached claims.

Claims

1. A back pressure device suitable for gas and supercritical fluid, characterized in that: include: A pneumatic valve, wherein one end of the pneumatic valve is provided with a first valve and a second valve, and the other end is used to connect to an external pipeline to introduce gas; a first tank body, wherein a first sealing piston is disposed in the first tank body, the first sealing piston being used to separate the first tank body into a first gas chamber and a first liquid chamber, the first gas chamber being provided with a first pressure relief port, and the first gas chamber being in communication with the first valve; a second tank body, wherein a second sealing piston is provided in the second tank body, the second sealing piston is used to separate the second tank body into a second gas chamber and a second liquid chamber, the second gas chamber is provided with a second pressure relief port, and the second gas chamber is connected to the second valve; A first liquid path and a second liquid path are provided between the first liquid chamber and the second liquid chamber to form a liquid circulation loop. A first back-pressure valve is provided on the first liquid path, and a second back-pressure valve is provided on the second liquid path. The pressures in the first back-pressure valve and the second back-pressure valve are consistent with the predetermined pressure in the external pipeline. The maximum capacities of the first liquid chamber and the second liquid chamber are consistent. The back pressure device suitable for gas and supercritical fluid has a first state and a second state. When it is in the first state, the first pressure relief port is closed, the second pressure relief port is opened, the first valve is opened, and the second valve is closed. When it is in the second state, the first pressure relief port is opened, the second pressure relief port is closed, the first valve is closed, and the second valve is opened.

2. The back pressure device applicable to gas and supercritical fluid according to claim 1, characterized in that: Also includes: a first sensor disposed on a side of the first gas chamber opposite to the first sealing piston; a second sensor disposed on a side of the second gas chamber opposite to the second sealing piston; a third sensor, the third sensor being disposed at the first valve; When the first sensor senses the first sealing piston and the pressure reaches the predetermined pressure, the first valve opens and the second valve closes; when the third sensor senses the first valve opening, the first pressure relief port closes and the second pressure relief port opens; When the second sensor senses the second sealing piston and the pressure reaches the predetermined pressure, the first valve closes and the second valve opens; when the third sensor senses that the first valve is closed, the first pressure relief port opens and the second pressure relief port closes.

3. The back pressure device applicable to gas and supercritical fluid according to claim 1, characterized in that: A first electric needle valve for controlling the opening or closing of the first pressure relief port is provided at the first pressure relief port.

4. The back pressure device applicable to gas and supercritical fluid according to claim 3, characterized in that: A second electric needle valve is provided at the second pressure relief port to control its opening or closing.

5. The back pressure device applicable to gas and supercritical fluid according to claim 1, characterized in that: Also includes: a first air pipe, one end of which is connected to the first air valve, a first air injection hole is provided on the first gas chamber, and the other end of the first air pipe is connected to the first air injection hole; A second air pipe, one end of the second air pipe is connected to the second air valve, a second air injection hole is provided on the second gas chamber, and the other end of the second air pipe is connected to the second air injection hole.

6. The back pressure device applicable to gas and supercritical fluid according to claim 5, characterized in that: Also includes: An air circuit one-way valve is provided, wherein the first air pipe and the second air pipe are respectively connected to the air circuit one-way valve.

7. The back pressure device applicable to gas and supercritical fluid according to claim 1, characterized in that: The first liquid chamber is provided with a first liquid discharge hole and a first liquid inlet hole, and the second liquid chamber is provided with a second liquid discharge hole and a second liquid inlet hole; The first liquid circuit includes a first liquid pipe and a second liquid pipe, the two ends of the first liquid pipe are respectively connected to the first liquid discharge hole and the first back pressure valve, and the two ends of the second liquid pipe are respectively connected to the first back pressure valve and the second liquid inlet hole; The second liquid circuit includes a third liquid pipe and a fourth liquid pipe. Both ends of the third liquid pipe are connected to the second liquid discharge hole and the second back pressure valve respectively. Both ends of the fourth liquid pipe are connected to the second back pressure valve and the first liquid inlet hole respectively.

8. The back pressure device applicable to gas and supercritical fluid according to claim 7, characterized in that: Also includes: Liquid circuit one-way valves are respectively provided on the first liquid pipe, the second liquid pipe, the third liquid pipe and the fourth liquid pipe.

9. The back pressure device applicable to gas and supercritical fluid according to claim 8, characterized in that: Also includes: The third tank body and the fifth liquid pipe, the top side of the third tank body is provided with a third liquid inlet hole, the bottom side of the third tank body is provided with a third liquid discharge hole, the two ends of the third liquid pipe are respectively connected to the second liquid discharge hole and the third liquid inlet hole, and the two ends of the fifth liquid pipe are respectively connected to the third liquid discharge hole and the second back pressure valve.

10. The back pressure device applicable to gas and supercritical fluid according to claim 9, characterized in that: The top side of the third tank body is also provided with a liquid injection hole.

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