A dissolved gas extraction device for in-situ detection in the deep sea

Abstract

This invention relates to the field of deep-sea sample testing, specifically to a dissolved gas extraction device for in-situ deep-sea testing. The device includes a sampling unit containing a sampling chamber and a back pressure chamber, a vacuum unit, a detection unit, and a built-in expander suspended within the sampling chamber. The built-in expander exhibits pressure response characteristics: when the sampling chamber is filled with high-pressure seawater, it is compressed to increase the flow area of ​​the annular channel; when the pressure decreases and the chamber is emptied, it expands to occupy the internal space of the sampling chamber. This invention utilizes the pressure difference between the deep-sea hydrostatic pressure and the vacuum chamber as a power source to directly drive the rapid flow of seawater and induce intense flash evaporation and desorption, quickly forming a headspace for detection. The dissolved gas extraction device achieves pump-free operation and optimizes fluid transport efficiency through the expander, significantly improving the extraction speed of dissolved gases.

Description

Technical Field

[0001] This invention relates to the field of deep-sea sample testing, and more specifically to a dissolved gas extraction device for in-situ deep-sea testing. Background Technology

[0002] In deep-sea in-situ dissolved gas detection, the core step is to transfer the gas dissolved in seawater (such as methane and hydrogen) to the gas phase space so that the sensor can detect it. Existing dissolved gas extraction technology usually adopts the method of directly connecting a cavity filled with seawater to a vacuum cavity.

[0003] In this mode, seawater remains still or flows through the gas-liquid interface at a low speed in a laminar state. The precipitation of dissolved gases in seawater is entirely limited by Fick's law, and the desorption rate of the gas mainly depends on the contact area and concentration gradient between the gas and liquid phases.

[0004] Because the specific surface area of ​​the macroscopic liquid surface is small and there is a lack of strong disturbance inside the liquid phase, dissolved gas molecules must rely on slow Brownian motion to diffuse from the depths of the liquid to the surface in order to escape. This physical process results in an extremely slow gas phase precipitation rate, which usually takes several minutes or even tens of minutes to reach gas-liquid equilibrium. This leads to a long response time for the detection system, which cannot meet the real-time requirements of rapid deep-sea cruise detection. Summary of the Invention

[0005] The purpose of this invention is to provide a dissolved gas extraction device for in-situ detection in the deep sea, which aims to utilize the atomization effect generated by high-energy jet impact to change the dissolved gas precipitation mechanism from slow surface diffusion to rapid flash evaporation and desorption, thereby increasing the gas precipitation rate.

[0006] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0007] A dissolved gas extraction device for in-situ detection in the deep sea, comprising:

[0008] The sampling unit includes an inlet switch valve, a sampling chamber, a center switch valve, a back pressure chamber, a reversing valve, and an outlet switch valve, which are connected in an axial sequence.

[0009] A vacuum unit includes a pre-evacuated vacuum chamber connected to a port of the reversing valve;

[0010] A detection unit is disposed at the top of the sampling cavity;

[0011] An internal expansion element is suspended at the geometric center of the sampling cavity;

[0012] The inlet switch valve is used to connect the external environment with the sampling chamber, the reversing valve is used to selectively connect the back pressure chamber to the vacuum chamber and the outlet switch valve, and the outlet switch valve is used to connect the back pressure chamber with the external environment.

[0013] The outer contour of the built-in expansion member and the inner wall of the sampling cavity define an annular flow channel. The built-in expansion member has pressure response characteristics: when the sampling cavity is filled with high-pressure seawater, the built-in expansion member is compressed, and its volume is reduced to increase the flow area of ​​the annular flow channel.

[0014] When the sampling chamber is emptied due to reduced pressure, the built-in expansion member expands, increasing in volume to occupy the internal space of the sampling chamber.

[0015] Furthermore, it also includes: a suspended impact diffuser is provided at the geometric center of the back pressure cavity, and when seawater is forced into the back pressure cavity, the seawater impacts the impact diffuser and is broken and atomized.

[0016] Furthermore, the impact diffuser includes a rigid core cone, which is fixed within the back pressure cavity;

[0017] A microporous skin covers the outer surface of the rigid core cone;

[0018] The microporous skin is made of a porous elastic material and is configured such that when the back pressure chamber is connected to the external environment, the microporous skin is compressed by fluid pressure, and the micropores on its surface close, so that the microporous skin presents a smooth outer surface.

[0019] When the back pressure chamber is connected to the vacuum chamber, the microporous skin expands outward, and the micropores on its surface open, resulting in a rough outer surface for the microporous skin.

[0020] Furthermore, the microporous skin is made of thermoplastic polyurethane, the micropores are Ω-shaped or V-shaped self-sealing slits, the opening length of the micropores is 20-50 micrometers, and the spacing between the micropores is 100-200 micrometers.

[0021] Furthermore, the bottom of the built-in expansion member is close to the inlet of the central switch valve, and the diameter of the expanded built-in expansion member is larger than the through diameter of the central switch valve, thereby preventing splashing droplets that bounce back from the back pressure chamber from entering the top of the sampling chamber.

[0022] Furthermore, the built-in expansion member includes a rigid mandrel and an elastic spindle body fitted on the outer surface of the rigid mandrel. The elastic spindle body is made of a closed-cell composite foam elastomer, which includes fluorosilicone rubber as a matrix and hollow polymer microspheres uniformly dispersed inside the matrix.

[0023] Furthermore, a contraction nozzle is provided at the top inlet of the back pressure chamber, the contraction nozzle is located at the downstream outlet of the central switch valve, and the contraction nozzle is aligned directly above the impact diffuser.

[0024] The converging nozzle has a flow cross-section that gradually decreases along the fluid flow direction. It is configured to converge the annular flow after rectification by the built-in expander into a high-pressure, high-speed columnar flow and direct it toward the impact diffuser.

[0025] Furthermore, the detection unit includes a hydrophobic and breathable filter element that encloses the probe of the detection unit, and the hydrophobic and breathable filter element is made of sintered polytetrafluoroethylene material, which is configured to allow gas molecules to pass through while blocking liquid water from contacting the probe.

[0026] Furthermore, the detection unit also includes a heat conduction base, on which the detection unit is mounted. The heat conduction base passes through the wall of the sampling chamber and directly contacts the external seawater, thereby conducting the ambient heat of the external seawater to the detection unit to prevent condensation from occurring on the surface of the detection unit.

[0027] The advantages of this invention compared to the prior art are:

[0028] This invention utilizes the pressure difference between the enormous hydrostatic pressure of the deep sea and the preset low pressure of the vacuum chamber as a power source. When the central switch valve is opened, this pressure difference directly drives the seawater sample to flow rapidly from the sampling chamber to the back pressure chamber, forcing the gas dissolved in the seawater to break the gas-liquid balance and undergo violent flash desorption, quickly forming a headspace in the sampling chamber for analysis by the detection unit. Attached Figure Description

[0029] 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.

[0030] Figure 1 This is a top view of an embodiment of the present invention;

[0031] Figure 2 for Figure 1 A quarter section view along the AA direction;

[0032] The labels in the diagram represent the following:

[0033] 1-Sampling unit; 11-Inlet switch valve; 12-Sampling chamber; 13-Center switch valve; 14-Back pressure chamber; 15-Reversing valve; 16-Outlet switch valve; 17-Contraction nozzle; 2-Vacuum unit; 3-Detection unit; 31-Hydrophobic and breathable filter element; 32-Heat conduction base; 4-Built-in expansion element; 41-Rigid mandrel; 42-Elastic spindle body; 5-Impact diffuser; 51-Rigid core cone; 52-Microporous skin. Detailed Implementation

[0034] 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.

[0035] This embodiment provides a dissolved gas extraction device for in-situ detection in the deep sea, which can drive fluid transport by utilizing the hydrostatic pressure of the deep sea environment and the pressure difference of the vacuum environment. The dissolved gas extraction device includes an inlet switch valve 11, a sampling chamber 12, a central switch valve 13, a back pressure chamber 14, a reversing valve 15, and an outlet switch valve 16 connected in an axial sequence, as well as a vacuum unit 2 connected to one port of the reversing valve 15. The vacuum unit 2 includes a vacuum chamber that has been pre-evacuated. A detection unit 3 is disposed at the top of the sampling chamber 12 for detecting gases precipitated from the liquid sample. This embodiment includes a built-in expansion member 4 suspended at the geometric center of the sampling chamber 12. The inlet switch valve 11 is used to connect the external environment and the sampling chamber 12, the reversing valve 15 is used to selectively connect the back pressure chamber 14 to the vacuum chamber and the outlet switch valve 16, and the outlet switch valve 16 is used to connect the back pressure chamber 14 and the external environment.

[0036] In the specific working process, in order to solve the problem of high energy consumption of fluid drive in the deep-sea high-pressure environment, this invention utilizes the huge potential energy difference between high-pressure seawater and vacuum environment as a power source; specifically, the outer contour of the built-in expansion member 4 and the inner wall of the sampling cavity 12 define an annular flow channel; the built-in expansion member 4 has pressure response characteristics: when the sampling cavity 12 is connected to the external environment and filled with high-pressure seawater, the built-in expansion member 4 is uniformly compressed, and its volume decreases to increase the flow area of ​​the annular flow channel, reduce fluid resistance, and enable seawater to quickly fill the sampling cavity 12; when the sampling cavity 12 is connected to the back pressure cavity 14 and the pressure decreases and it is emptied, the built-in expansion member 4 expands by relying on the elastic potential energy of the material itself, and its volume increases to occupy the internal space of the sampling cavity 12, thereby helping to squeeze out the residual fluid and reduce the dead volume of the system.

[0037] Furthermore, in order to achieve the purpose of rapidly transferring dissolved gas from the liquid phase to the gas phase space, this embodiment provides a converging nozzle 17 at the top inlet of the back pressure chamber 14, and the converging nozzle 17 is connected to the downstream outlet of the central switching valve 13; at the same time, a suspended impact diffuser 5 is provided at the geometric center of the back pressure chamber 14, and the converging nozzle 17 is aligned directly above the impact diffuser 5; the converging nozzle 17 has a flow cross section that gradually decreases along the fluid flow direction, and it is constructed to convert the potential energy of the high-pressure fluid into kinetic energy according to Bernoulli's principle, and to converge the annular flow after rectification by the built-in expander 4 into a high-pressure, high-speed columnar flow, which is then directed toward the impact diffuser 5; when seawater impacts the impact diffuser 5, the fluid undergoes mechanical breakage and atomization, thereby forming a headspace in the sampling chamber 12, which is used by the detection unit 3 to detect the gas in the headspace.

[0038] To resolve the contradiction between "atomization efficiency" and "cleaning residue" in traditional fixed targets, the aforementioned impact diffuser 5 employs a variable surface structure. Specifically, the impact diffuser 5 includes a rigid core cone 51 fixed within the back pressure chamber 14, and a microporous skin 52 covering the outer surface of the rigid core cone 51. The microporous skin 52 is made of a porous elastic material, preferably thermoplastic polyurethane. The surface of the microporous skin 52 is provided with micropores, which are Ω-shaped or V-shaped self-sealing slits with an opening length of 20-50 micrometers and a spacing of 100-200 micrometers. This structure gives the impact diffuser 5 the following operating characteristics: In the high-pressure flushing environment where the back pressure chamber 14 is connected to the external environment, the microporous skin 52 is compressed by the fluid pressure, and the micropores on its surface close, making the microporous skin 52 have a smooth outer surface to facilitate the sliding of residual droplets and prevent cross-contamination; In the low-pressure atomization environment where the back pressure chamber 14 is connected to the vacuum chamber, the microporous skin 52 expands outward, and the micropores on its surface open, making the microporous skin 52 have a rough outer surface to increase the mechanical shear force when the fluid impacts and improve the atomization effect.

[0039] Furthermore, in order to address the issue that splashing droplets in the back pressure chamber 14 may contaminate the detection unit 3 in reverse, while also ensuring fluid flow during sampling, this embodiment utilizes the geometric deformation of the built-in expansion member 4 to achieve passive protection. Specifically, the built-in expansion member 4 includes a rigid mandrel 41 and an elastic spindle body 42 fitted on the outer surface of the rigid mandrel 41. The elastic spindle body 42 is made of a closed-cell composite foam elastomer, including fluorosilicone rubber as the matrix and hollow polymer microspheres uniformly dispersed inside the matrix.

[0040] Based on the material properties, when the built-in expansion member 4 is compressed under high-pressure seawater, the volume of the elastic spindle body 42 shrinks and the outer diameter decreases, thereby opening a wide annular flow channel for fluid to pass through; when the built-in expansion member 4 expands in the emptied state (i.e. when the pressure in the sampling chamber 12 decreases), the volume of the elastic spindle body 42 increases, and its maximum outer diameter approaches the inner wall of the sampling chamber 12; at this time, the expanded elastic spindle body 42 acts as a huge physical baffle in space, effectively blocking the high-speed splashing droplets that bounce back from the back pressure chamber 14 below, forcing the splashing droplets to flow back under the action of gravity, thereby protecting the detection unit 3 located at the top.

[0041] Furthermore, to address the survival and operational stability issues of the detection unit 3 in harsh deep-sea and flash evaporation environments, the detection unit 3 includes a hydrophobic and breathable filter element 31 and a heat-conducting base 32. The hydrophobic and breathable filter element 31 encloses the probe of the detection unit 3 and is made of sintered polytetrafluoroethylene material. Utilizing its hydrophobic properties and microporous structure, the hydrophobic and breathable filter element 31 is configured to allow gas molecules to pass through while blocking liquid water from contacting the probe. Simultaneously, the detection unit 3 is mounted on the heat-conducting base 32, which passes through the wall of the sampling chamber 12 and directly contacts the external seawater. Although the temperature inside the chamber decreases due to heat absorption from flash evaporation, the heat-conducting base 32 can conduct ambient heat from the external seawater to the detection unit 3, maintaining the surface temperature of the detection unit 3 at a level close to the ambient seawater temperature. This prevents condensation on the surface of the detection unit 3 due to excessively low temperatures, ensuring the accuracy of the detection data.

[0042] In summary, a complete working cycle of the dissolved gas extraction device of the present invention includes the following steps.

[0043] Step 1, System Flushing and Loading: The inlet switch valve 11, center switch valve 13, and outlet switch valve 16 are all in the open state, and the reversing valve 15 is in the position connecting the back pressure chamber 14 and the outlet switch valve 16. Under the action of hydrostatic pressure, high-pressure seawater flows sequentially through the inlet switch valve 11, sampling chamber 12, center switch valve 13, back pressure chamber 14, reversing valve 15, and outlet switch valve 16, forming a continuous flushing flow path. In this state, the sampling chamber 12 is filled with high-pressure seawater, and the elastic spindle body 42 of the built-in expansion member 4 is uniformly compressed, reducing its volume and thus opening a wide annular flow channel for rapid fluid passage. Simultaneously, the microporous skin 52 in the back pressure chamber 14 is compressed by fluid pressure, closing the surface micropores and presenting a smooth state, which is conducive to being flushed and cleaned by high-speed water flow to remove residues from the previous cycle.

[0044] Step 2, Vacuum Preset: Control the inlet switch valve 11, center switch valve 13 and outlet switch valve 16 to close; then control the reversing valve 15 to activate, so that the back pressure chamber 14 is connected to the vacuum unit 2; at this time, the residual liquid in the back pressure chamber 14 is extracted, and a low-pressure (close to vacuum) environment is established inside; during this process, as the pressure in the back pressure chamber 14 decreases, the microporous skin 52 on the surface of the impact diffuser 5 expands outward due to its own elasticity, the micropores open, and a rough surface is presented, which prepares for subsequent atomization; at the same time, as the inlet switch valve 11 is closed, the high-pressure sample in the sampling chamber 12 is sealed, and the built-in expansion member 4 maintains the compressed state.

[0045] Step 3, Triggering and Flash Evaporation: Keep the inlet switch valve 11 and outlet switch valve 16 closed; control the reversing valve 15 to switch to the position connecting the back pressure chamber 14 and the outlet switch valve 16; since the outlet switch valve 16 is closed at this time, the back pressure chamber 14 is actually in a closed vacuum state; then, the center switch valve 13 is opened instantaneously; driven by the huge pressure difference between the sampling chamber 12 (high pressure) and the back pressure chamber 14 (closed low pressure), the seawater in the sample area is accelerated through the contraction nozzle 17 to form a high-speed jet, which impacts the rough impact diffuser 5; the seawater is instantly broken and atomized, and the dissolved gas is rapidly desorbed and forms a gas-rich headspace in the free space of the system; during this process, the pressure in the sampling chamber 12 decreases, and the built-in expansion member 4 expands rapidly to occupy the space. Its expanded spindle shape effectively blocks the droplets splashed back by the impact diffuser 5, preventing them from touching the detection unit 3.

[0046] Step 4, Detection and Analysis: Maintaining the above state, the released gas diffuses to the detection unit 3 at the top of the sampling chamber 12; the probe of the detection unit 3, under the protection of the hydrophobic and breathable filter element 31, analyzes the gas composition in the headspace; during this period, the heat conduction base 32 continuously transfers the ambient heat of the external seawater to the probe to prevent condensation droplets from appearing on the probe surface.

[0047] Step 5, Drainage and Reset: After the test is completed, the inlet switch valve 11, the center switch valve 13, and the outlet switch valve 16 are reopened, and the reversing valve 15 is kept connected to the back pressure chamber 14 and the outlet switch valve 16; the system returns to the state of Step 1, and new high-pressure seawater from the outside rushes in again, compressing the built-in expansion component 4 and the microporous skin 52 again, and pushing the test waste liquid of this cycle out of the system, completing the self-cleaning and preparing to enter the next working cycle.

[0048] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.

Claims

1. A dissolved gas extraction device for in-situ detection of deep sea, characterized by, Comprising: a sampling unit (1) comprising an inlet on-off valve (11), a sampling cavity (12), a center on-off valve (13), a back pressure cavity (14), a reversing valve (15) and an outlet on-off valve (16) connected in axial sequence; a vacuum unit (2) comprising a vacuum chamber pre-evacuated, connected to a port of the reversing valve (15); a detection unit (3) disposed on top of the sampling cavity (12); an internal expansion (4) suspended in the geometric center of the sampling cavity (12); wherein the inlet on-off valve (11) is used to communicate the external environment with the sampling cavity (12), the reversing valve (15) is used to selectively communicate the back pressure cavity (14) to the vacuum chamber and the outlet on-off valve (16), and the outlet on-off valve (16) is used to communicate the back pressure cavity (14) and the external environment; the outer contour of the internal expansion (4) and the inner wall of the sampling cavity (12) define an annular flow channel, and the internal expansion (4) has a pressure response characteristic: in the state that the sampling cavity (12) is filled with high-pressure seawater, the internal expansion (4) is compressed, the volume is reduced to increase the flow area of the annular flow channel; in the state that the sampling cavity (12) is emptied with reduced pressure, the internal expansion (4) expands, the volume increases to occupy the internal space of the sampling cavity (12).

2. The dissolved gas extraction device of claim 1, wherein, Further comprising: the geometric center of the back pressure cavity (14) is provided with a suspended impact diffuser (5), when seawater is pressed into the back pressure cavity (14), the seawater hits the impact diffuser (5) and breaks and atomizes.

3. The dissolved gas extraction device according to claim 2, characterized in that, the impact diffuser (5) comprises: a rigid core cone (51) fixed in the back pressure cavity (14); a microporous skin (52) covering the outer surface of the rigid core cone (51); wherein the microporous skin (52) is made of porous elastic material and is configured to: when the back pressure cavity (14) is connected to the external environment, the microporous skin (52) is compressed by fluid pressure, the micropores on its surface are closed, so that the microporous skin (52) presents a smooth outer surface; when the back pressure cavity (14) is connected to the vacuum chamber, the microporous skin (52) expands outward, the micropores on its surface open, so that the microporous skin (52) presents a rough outer surface.

4. The dissolved gas extraction device according to claim 3, characterized in that, the microporous skin (52) is made of thermoplastic polyurethane, the micropores are self-sealing slits in Ω or V shape, the opening length of the micropores is 20-50 microns, and the spacing of the micropores is 100-200 microns.

5. The dissolved gas extraction device according to claim 2, characterized in that, the bottom of the internal expansion (4) is close to the inlet of the center on-off valve (13), and the diameter of the internal expansion (4) after expansion is greater than the through-passage of the center on-off valve (13), so as to block the splash droplets rebounding from the back pressure cavity (14) from entering the top of the sampling cavity (12).

6. The dissolved gas extraction device according to claim 5, wherein the built-in expansion element (4) comprises a rigid mandrel (41), and an elastic spindle (42) sleeved on the outer surface of the rigid mandrel (41), the elastic spindle (42) is made of closed-cell composite foam elastomer, which comprises fluorosilicone rubber as a matrix, and hollow polymer microspheres uniformly dispersed inside the matrix.

7. The dissolved gas extraction device according to claim 2, wherein a contraction nozzle (17) is arranged at the top inlet of the back pressure cavity (14), the contraction nozzle (17) is arranged at the downstream outlet of the center on-off valve (13), and the contraction nozzle (17) is aligned directly above the impingement diffuser (5); the contraction nozzle (17) has a gradually decreasing flow passage cross section along the fluid flow direction, which is configured to constrict the annular flow after rectification by the built-in expansion element (4) into a high-pressure high-speed columnar flow, and shoot towards the impingement diffuser (5).

8. The dissolved gas extraction device according to claim 1, wherein the detection unit (3) comprises a hydrophobic air-permeable filter element (31), which wraps the probe of the detection unit (3), and the hydrophobic air-permeable filter element (31) is made of sintered polytetrafluoroethylene material, which is configured to allow gas molecules to pass through and block liquid water from contacting the probe.

9. The dissolved gas extraction device according to claim 1, wherein the detection unit (3) further comprises a heat-conducting base (32), on which the detection unit (3) is installed, the heat-conducting base (32) directly contacts the ambient seawater through the wall of the sampling cavity (12), and is configured to conduct the environmental heat of the ambient seawater to the detection unit (3) to prevent condensation on the surface of the detection unit (3).

Images