A gas-liquid balance sampling system based on vacuum negative pressure driving and a method thereof

Abstract

The application discloses a kind of gas-liquid balance sampling systems and methods based on vacuum negative pressure drive, including low-pressure tank and high-pressure tank, sample solution is loaded in high-pressure tank, and high-pressure tank is provided with baffle, baffle separates high-pressure tank inner chamber into first cavity and second cavity, first cavity is connected with low-pressure tank by first flow guide pipe, first control valve is arranged on first flow guide pipe, shunt hole is arranged on baffle, second control valve is arranged in shunt hole.The application realizes the automatic formation of sampling cavity and the efficient precipitation of target gas through two times of sequential controllable negative pressure operation, does not rely on carrier gas, consumable components such as fragile membrane, so that the overall structure is simple, low in cost and convenient to maintain, and the device can be submerged into seabed or deep water to locate and precipitate in real time in specific water layer, without sampling to analysis room for precipitation operation, the overall process is convenient and fast.

Description

Technical Field

[0001] This invention relates to the field of experimental preparation technology, specifically to a gas-liquid balance sampling system and method based on vacuum negative pressure drive. Background Technology

[0002] In the field of environmental science, qualitative and quantitative analysis of dissolved gases in liquids is crucial. For example, monitoring greenhouse gases such as dissolved oxygen (DO), carbon dioxide (CO2), and methane (CH4) in water bodies requires efficient and accurate separation and collection of the target gases from the liquid phase for use by subsequent analytical instruments (such as gas chromatographs).

[0003] Currently, traditional methods for extracting dissolved gases from liquids mainly include purge-and-trap and membrane separation. However, these methods have significant limitations in practical application. Purge-and-trap typically uses inert gases (such as nitrogen or helium) to continuously purge liquid samples, which consumes a large amount of high-purity carrier gas. Membrane separation requires components such as hollow fiber membranes, and although it can achieve continuous online sampling, its core components are expensive and have a limited lifespan. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0005] A gas-liquid balance sampling system driven by vacuum negative pressure includes a low-pressure tank and a high-pressure tank with a pressure difference inside the tank. The high-pressure tank is loaded with a sample solution and is equipped with a partition that divides the inner cavity of the high-pressure tank into a first cavity and a second cavity.

[0006] The first cavity is connected to the low-pressure tank through a first guide pipe. The first guide pipe is equipped with a first control valve. When the first control valve is opened, the sample solution in the first cavity is discharged to the low-pressure tank by utilizing the pressure difference principle, thus forming a low-pressure cavity.

[0007] The partition plate is provided with a diversion hole, and a second control valve is provided in the diversion hole. When the second control valve is opened, the target gas dissolved in the sample solution in the second cavity is released into the low-pressure cavity by using Henry's law.

[0008] As a preferred embodiment of the present invention, the high-pressure tank is provided with two liquid inlets, the two liquid inlets are coaxially arranged with the diversion hole, and a third control valve is provided in the two liquid inlets.

[0009] As a preferred embodiment of the present invention, both the second control valve and the third control valve are rotary closed-type on / off valves.

[0010] In a preferred embodiment of the present invention, the first control valve, the second control valve, and the third control valve are all electrically / signally connected to an external control unit.

[0011] As a preferred embodiment of the present invention, the bottom of the low-pressure tank is provided with a drain hole, and a drainage component is provided on the drain hole.

[0012] As a preferred embodiment of the present invention, the drainage assembly includes a bidirectional pressure pump and an air storage tank;

[0013] The bidirectional pressure pump draws the gaseous medium in the low-pressure tank into the gas storage tank to create a low-pressure state in the low-pressure tank.

[0014] The bidirectional pressure pump discharges the gaseous medium in the gas storage tank in the reverse direction into the low-pressure tank, thereby discharging the waste liquid from the drain hole.

[0015] As a preferred embodiment of the present invention, the second cavity is connected to the low-pressure tank through a second guide pipe, a fourth control valve is provided on the second guide pipe, and the end of the second guide pipe is located on the exhaust port side of the bidirectional pressure pump.

[0016] When the bidirectional pressure pump pressurizes the low-pressure tank by venting gas, the exhaust port of the bidirectional pressure pump draws the sample solution in the second cavity into the low-pressure tank and discharges it simultaneously through the pressure difference principle.

[0017] As a preferred embodiment of the present invention, the second flow guide pipe is a Venturi tube.

[0018] A sampling method based on the above-mentioned vacuum negative pressure driven gas-liquid balance sampling system includes:

[0019] Step 1: Configure two tanks, a low-pressure tank and a high-pressure tank, which have an internal pressure difference and are connected by a first control valve. The high-pressure tank has a first cavity and a second cavity connected by a second control valve.

[0020] Step 2: Open the first control valve and close the second control valve. Use the pressure difference principle to empty the first cavity connected to the first control valve and create a low-pressure state in the first cavity.

[0021] Step 3: Close the first control valve and open the second control valve. Using Henry's Law, the target gas dissolved in the sample solution in the second cavity is precipitated into the first cavity under low pressure, thereby sampling the target gas at the headspace position of the first cavity.

[0022] As a preferred embodiment of the present invention, the sampling method further includes:

[0023] Step 4: Configure a drainage component inside the low-pressure tank, and configure a second guide pipe connected to the second cavity at the air inlet end of the drainage component. The drainage component pressurizes the low-pressure tank by introducing air from the air inlet end, and discharges the solution in the low-pressure tank from the water outlet end of the drainage component. During the drainage process, the solution in the second cavity is discharged synchronously by utilizing the Venturi effect.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This invention achieves automatic formation of the sampling chamber and efficient precipitation of the target gas through two sequentially controllable negative pressure operations. It does not rely on consumable components such as carrier gas and fragile membranes, making the overall structure simple, low-cost, and easy to maintain. Furthermore, this device can be submerged into the seabed or deep water to locate and precipitate specific water layers in real time without the need to take samples to the analysis chamber for precipitation operations. The whole process is convenient and fast. Attached Figure Description

[0026] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0028] The labels in the diagram represent the following:

[0029] 1. Low-pressure tank; 2. High-pressure tank; 3. Baffle plate; 4. First cavity; 5. Second cavity; 6. First guide pipe; 7. First control valve; 8. Second control valve; 9. Third control valve; 10. Drain hole; 11. Drainage assembly; 12. Two-way pressure pump; 13. Gas storage tank; 14. Second guide pipe; 15. Fourth control valve. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1As shown, this invention provides a vacuum-driven gas-liquid balance sampling system for extracting dissolved target gases from liquid samples. Specifically, it includes a low-pressure tank 1 and a high-pressure tank 2, which are connected by pipes and maintain a certain pressure difference. The high-pressure tank 2 is made of a corrosion-resistant material (such as stainless steel) and contains a sample solution (such as an aqueous solution containing methane). The high-pressure tank 2 has a partition 3 inside, dividing the inner cavity into an upper first cavity 4 and a lower second cavity 5. The partition 3 is designed to be sealed to prevent uncontrolled exchange of substances.

[0032] The first cavity 4 is connected to the low-pressure tank 1 via the first guide pipe 6. A first control valve 7 (such as a solenoid valve or pneumatic valve) is installed on the first guide pipe 6, which is opened or closed by an external control signal. When the first control valve 7 is open, due to the pressure difference between the high-pressure tank 2 and the low-pressure tank 1, the sample solution in the first cavity 4 is driven to flow into the low-pressure tank 1 through the first guide pipe 6, simultaneously creating a low-pressure state relative to the second cavity 5 inside the first cavity 4. The partition 3 has one or more diversion holes, each equipped with a second control valve 8 (such as a solenoid valve or pneumatic valve). When the second control valve 8 is open, the second cavity 5 is connected to the first cavity 4. Since the first cavity 4 has reached a low-pressure state, according to Henry's Law (the partial pressure of a dissolved gas is proportional to its concentration in its solution), the target gas dissolved in the second cavity 5 (such as CO2, CH4, or H2S) precipitates from the solution due to the pressure reduction and enters the headspace region of the first cavity 4, thereby achieving the sampling of the target gas.

[0033] Taking a water sample containing dissolved methane (CH4) as an example, the pressure inside the high-pressure tank 2 is 2 MPa, and the low-pressure tank 1 is a vacuum tank with an initial pressure of 101 Pa. After opening the first control valve 7, the sample solution in the first cavity 4 is transferred to the low-pressure tank 1, and the pressure in the first cavity 4 is balanced with that in the high-pressure tank 2, with the pressure in the first cavity 4 dropping to 1 MPa. Subsequently, the first control valve 7 is closed, and the second control valve 8 is opened. Due to the low-pressure environment in the top of the first cavity 4, the methane gas in the second cavity 5 precipitates into the first cavity 4 and concentrates at the top of the first cavity 4, thus enabling precipitation and collection.

[0034] Furthermore, in addition to manually adding the target solution into the high-pressure tank 2, this device can also be lowered underwater or to the seabed for real-time localized precipitation of solutions at different water layers. Specifically, the high-pressure tank 2 is equipped with two inlets coaxial with the diversion orifice, and a third control valve 9 is installed inside each inlet.

[0035] In specific implementation, such as Figure 1As shown, the high-pressure tank 2 has two liquid inlets on its top. When the high-pressure tank 2 is placed in water, both liquid inlets and the diversion hole are open. At this time, the entire high-pressure tank 2 is similar to a hollow cylinder and can be directly and quickly filled with the target solution in the water. The positions of the two liquid inlets are coaxially aligned with the diversion hole on the baffle 3 in the vertical direction to ensure fluid dynamic balance during liquid injection and reduce the impact of turbulence on the baffle 3 and the diversion hole.

[0036] Then, by operating the first control valve 7 and the second control valve 8, the target gas can be extracted from the target water layer using vacuum drive.

[0037] Furthermore, both the second control valve 8 and the third control valve 9 are rotary closed-type on / off valves. The second control valve 8 (located within the diversion orifice) and the third control valve 9 (located within the inlet) both employ rotary closed-type on / off valves (such as ball valves or butterfly valves) to ensure rapid opening and closing and reliable sealing. The valves are made of corrosion-resistant stainless steel or ceramic, with a valve core rotation angle of 90° and an on / off response time of less than 1 second.

[0038] In addition, the first, second, and third control valves 9 are all connected to an external control unit via electrical / signal connections. The external control unit (such as a PLC or embedded microcontroller) controls the opening and closing states of the first, second, and third control valves 9 via electrical or digital signals (such as 4-20 mA current signals or Modbus protocol), thereby facilitating valve opening and closing control from the external ship's compartment.

[0039] The low-pressure tank 1 is provided with a drain hole 10 at the bottom, and a drainage component 11 is provided on the drain hole 10. It is used to drain the sample solution or waste liquid transferred from the high-pressure tank 2.

[0040] Furthermore, in practical use, the entire device can be lifted onto the deck of the ship and the drain outlet can be manually opened to discharge the waste liquid. In order to avoid the large weight of the entire device containing waste liquid and the inconvenience of discharging the waste liquid on the deck, this device further provides a specific structure of the drainage component 11.

[0041] The drainage assembly 11 includes a bidirectional pressure pump 12 and a gas storage tank 13. The bidirectional pressure pump 12 creates a low-pressure state in the low-pressure tank 1 by suction or by reverse exhaust to discharge waste liquid from the drain hole 10. In suction mode, the bidirectional pressure pump 12 draws gaseous media (such as air or precipitated gas) from the low-pressure tank 1 into the gas storage tank 13, so that the low-pressure tank 1 does not need to use a separate air compressor to create low pressure in the sampling chamber, but is directly treated by negative pressure by this bidirectional pressure pump 12. In drainage mode, the bidirectional pressure pump 12 pumps the gaseous media in the gas storage tank 13 back into the low-pressure tank 1, creating a slight positive pressure, which pushes the waste liquid inside to be discharged through the drain hole 10, thus enabling the internal waste liquid to be smoothly discharged underwater under water pressure.

[0042] Furthermore, after gas sampling is completed in high-pressure tank 2, the solution in the second cavity 5 does not need to be taken into the hull and can be discharged underwater. Therefore, this device further connects the second cavity 5 to the low-pressure tank 1 through the second guide pipe 14. The second guide pipe 14 is equipped with a fourth control valve 15, and the end of the second guide pipe 14 is located on the exhaust port side of the bidirectional pressure pump 12 (not shown in the figure). When the pump is pressurized by exhaust, the solution in the second cavity 5 is simultaneously drawn in. Specifically, the end of the second guide pipe 14 is close to the exhaust port of the bidirectional pressure pump 12. When the bidirectional pressure pump 12 exhausts and pressurizes the low-pressure tank 1, the airflow at the exhaust port generates a local negative pressure (based on Bernoulli's principle), which draws the sample solution in the second cavity 5 into the low-pressure tank 1 through the second guide pipe 14, achieving simultaneous drainage. Furthermore, the second guide pipe 14 is configured as a Venturi tube, with a constriction section in the middle section forming a throat to enhance the negative pressure effect when the fluid passes through. When the bidirectional pressure pump 12 exhausts gas, the airflow generates a stronger negative pressure through the throat of the venturi tube, further improving the aspiration efficiency of the sample solution in the second cavity 5.

[0043] A sampling method based on the above-mentioned vacuum negative pressure driven gas-liquid balance sampling system includes:

[0044] Step 1: Configure two low-pressure tanks 1 and 2 that have an internal pressure difference and are connected by a first control valve 7. The high-pressure tank 2 has a first cavity 4 and a second cavity 5 that are connected by a second control valve 8.

[0045] Step 2: Open the first control valve 7 and close the second control valve 8. Use the pressure difference principle to empty the first cavity 4 connected to the first control valve 7 and create a low-pressure state in the first cavity 4.

[0046] Step 3: Close the first control valve 7 and open the second control valve 8. Using Henry's Law, the target gas dissolved in the sample solution in the second cavity 5 is precipitated into the first cavity 4 under low pressure, thereby sampling the target gas at the headspace position of the first cavity 4.

[0047] The method also includes:

[0048] Step 4: A drainage component 11 is installed in the low-pressure tank 1, and a second guide pipe 14 connected to the second cavity 5 is installed at the air inlet end of the drainage component 11. The drainage component 11 pressurizes the low-pressure tank 1 by introducing air from the air inlet end, and discharges the solution in the low-pressure tank 1 from the water outlet end of the drainage component 11. During the drainage process, the solution in the second cavity 5 is discharged synchronously by utilizing the Venturi effect.

[0049] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A gas-liquid balance sampling system based on vacuum negative pressure drive, characterized in that: The container includes a low-pressure tank (1) and a high-pressure tank (2) with a pressure difference inside the container. The high-pressure tank (2) is filled with a sample solution and is equipped with a partition (3) that divides the inner cavity of the high-pressure tank (2) into a first cavity (4) and a second cavity (5). The first cavity (4) is connected to the low-pressure tank (1) through the first guide pipe (6). The first guide pipe (6) is provided with a first control valve (7). When the first control valve (7) is opened, the sample solution in the first cavity (4) is discharged to the low-pressure tank (1) by utilizing the pressure difference principle, and a low-pressure cavity is formed. The partition (3) is provided with a diversion hole, and a second control valve (8) is provided in the diversion hole. When the second control valve (8) is opened, the target gas dissolved in the sample solution in the second cavity (5) is released into the low-pressure cavity by using Henry's law.

2. The gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 1, characterized in that: The high-pressure tank (2) is provided with two liquid inlets, which are coaxially arranged with the diversion hole, and a third control valve (9) is provided in the two liquid inlets.

3. The gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 2, characterized in that: Both the second control valve (8) and the third control valve (9) are rotary closed-type on / off valves.

4. A gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 2, characterized in that: The first control valve (7), the second control valve (8) and the third control valve (9) are all connected to an external control unit via electrical / signal connections.

5. A gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 4, characterized in that: The low-pressure tank (1) is provided with a drain hole (10) at the bottom, and a drainage component (11) is provided on the drain hole (10).

6. A gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 5, characterized in that: The drainage assembly (11) includes a bidirectional pressure pump (12) and an air storage tank (13). The bidirectional pressure pump (12) draws the gaseous medium in the low-pressure tank (1) into the gas storage tank (13) to form a low-pressure state in the low-pressure tank (1); The bidirectional pressure pump (12) discharges waste liquid from the drain hole (10) by reversing the flow of gaseous medium in the gas storage tank (13) into the low-pressure tank (1).

7. A gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 6, characterized in that: The second cavity (5) is connected to the low-pressure tank (1) through the second guide pipe (14). A fourth control valve (15) is provided on the second guide pipe (14). The end of the second guide pipe (14) is located on the exhaust port side of the bidirectional pressure pump (12). When the bidirectional pressure pump (12) vents and pressurizes the low-pressure tank (1), the exhaust port of the bidirectional pressure pump (12) draws the sample solution in the second cavity (5) into the low-pressure tank (1) and discharges it synchronously through the pressure difference principle.

8. A gas-liquid balance sampling system based on vacuum negative pressure drive according to claim 7, characterized in that: The second guide tube (14) is a Venturi tube.

9. A sampling method based on the vacuum negative pressure driven gas-liquid balance sampling system according to any one of claims 1-8, characterized in that, include: Step 1: Configure two low-pressure tanks (1) and high-pressure tanks (2) that have an internal pressure difference and are connected by a first control valve (7), wherein the high-pressure tank (2) has a first cavity (4) and a second cavity (5) connected by a second control valve (8); Step 2: Open the first control valve (7) and close the second control valve (8). Use the pressure difference principle to empty the first cavity (4) connected to the first control valve (7) and form a low-pressure state in the first cavity (4); Step 3: Close the first control valve (7) and open the second control valve (8). Using Henry's law, the target gas dissolved in the sample solution in the second cavity (5) is released into the first cavity (4) under low pressure, so that the target gas is sampled at the headspace position of the first cavity (4).

10. A sampling method according to claim 9, characterized in that, Also includes: Step 4: A drainage assembly (11) is installed in the low-pressure tank (1), and a second guide pipe (14) connecting the second cavity (5) is installed at the air inlet end of the drainage assembly (11). The drainage assembly (11) pressurizes the low-pressure tank (1) by introducing air from the air inlet end, and discharges the solution in the low-pressure tank (1) from the water outlet end of the drainage assembly (11). During the drainage process, the solution in the second cavity (5) is discharged synchronously by utilizing the Venturi effect.

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