CN117969193A - Jacket needle type convection displacement positive pressure sampling device - Google Patents

Abstract

The invention provides a jacket needle type convection displacement positive pressure sampling device, which is characterized in that when gas displacement and gas sampling are carried out on a sampling tank, a sampling needle is utilized to probe to the bottom of the sampling tank, and convection is formed in the sampling tank skillfully, so that the original gas in the sampling tank is effectively removed through the bottom-up convection action in the gas displacement stage, and further, the existence of the sampling needle is used as a flow limiting buffer in the gas sampling stage, so that the gas pressure is orderly increased and is prevented from being instantaneously swelled, and the sampling tank is prevented from bearing excessive pressure in a short time. The sampling needle also plays a function of series connection, and two or more sampling tanks are effectively connected in series through the series connection of the sampling needle, so that the parallel propulsion and sample backup of the two or more sampling tanks in the two aspects of gas replacement and gas sampling can be realized.

Description

Jacketed needle convection displacement positive pressure sampling device

Technical Field

The invention relates to a jacketed needle type convection displacement positive pressure sampling device.

Background technique

Pressure tank sampling is widely used in underground coal mines, metallurgy, tunnel engineering, refineries, environmental protection, health and epidemic prevention, etc., in order to quickly determine the concentration of volatile organic compounds (VOCs), toxic and harmful gases and odorous gases (such as carbon monoxide, carbon dioxide, hydrogen sulfide) in the on-site environment.

However, the existing positive pressure tank sampling system has many defects. First, the system setting of the sampling tank is difficult to achieve real-time replacement. During the gas sampling process, it is often only possible to use pressurization and vacuuming alternately. In addition, the sampling pump has limited pushing (pressure) force. After multiple cleaning and replacement, there will always be some residual gas in the sampling tank. The retention of residual gas will seriously affect the detection accuracy of the sampled gas, and long-term retention will seriously pollute the sampling tank.

Secondly, in the prior art, although the sampling tank can be pressurized and flushed multiple times, the flushing process often adopts a sandwich stacking cleaning method, which often fails to completely remove the residual gas, resulting in inaccuracy and interference in the composition of the gas samples collected by subsequent pressurization. In addition, the sampling efficiency is not high, and the single sampling time is long, with a single sampling cycle often reaching half an hour or even 1 hour.

Thirdly, during the positive pressure sampling process, the positive pressure sampling flow path structure of the existing sampling pump is relatively complex, with many gas path components, pipelines and interfaces, which are prone to leakage and contamination, and cleaning and replacement require frequent manual switching of the switch valve, resulting in more complicated operation.

Summary of the invention

The present invention provides a jacketed needle type convection displacement positive pressure sampling device, which effectively solves the above-mentioned defects existing in the prior art.

Specifically, the present invention provides a jacketed needle-type convection displacement positive pressure sampling device, which can realize a displacement sampling flow path and a pressurized sampling flow path. In the device, a connecting port is connected to a sampling tank through a first pipeline and then through a sampling needle fluid, and the sampling tank is then connected to an outlet through a second pipeline through the sampling needle. A sampling pump is arranged on the first pipeline or the second pipeline, wherein a front switch valve is arranged on the passage of the first pipeline, and a rear switch valve is arranged on the passage of the second pipeline. The sampling needle comprises an embedded needle, an outer liner, and an interface component. One end of the embedded needle is connected to the first pipeline outside the sampling tank, and the other end extends to the bottom of the sampling tank. The interface component surrounds the embedded needle and is connected to the top opening of the sampling tank. The outer liner extends from the interface component and is connected to the second pipeline. The device starts a displacement sampling flow path, wherein the front switch valve and the rear switch valve are both opened, the sampling port is fixedly connected to the connecting port, the sampling pump presses the self-sampling gas pump into the sampling port, the sampling gas flows through the first pipeline and then through the embedded needle and is sent to the bottom of the sampling tank, the sampling gas forms convection from bottom to top in the sampling tank, thereby pushing the original gas in the sampling tank from bottom to top through the interface part and out of the outer liner, thereby, the original gas is blown out of the outlet through the second pipeline together with the sampling gas; then, the device switches to a pressurized sampling flow path, wherein the rear switch valve is closed, thereby, the sampling gas from the sampling port is input to the connecting port, the sampling gas flows through the first pipeline and then through the embedded needle and is blown into the sampling tank, thereby collecting and accumulating the sampling gas in the sampling tank, the sampling gas in the sampling tank gradually increases in pressure from the bottom of the tank, and when the pressure increases to a specific threshold, the front switch valve is closed.

Preferably, the sampling needle is inertly coated with molten silicon.

Preferably, a pressure gauge is installed on the passage of the first pipeline. During the operation of the pressurized sampling flow path, the reading in the pressure gauge gradually increases. Once the reading in the pressure gauge is greater than a specific threshold, the front switch valve is closed, causing both the front switch valve and the rear switch valve to close, thereby terminating the gas supply to the sampling tank.

Preferably, the embedded needle is inserted into the sampling tank at a position 2-5 cm from the tank bottom.

The present invention also provides a jacketed needle-type convection displacement positive pressure sampling device, which can realize a displacement sampling flow path and a pressurized sampling flow path. In the device, the connecting port is connected to the second sampling tank through the first pipeline and then through the second sampling needle fluid, the second sampling needle is then connected to the first sampling needle through the first sampling needle, the first sampling needle is connected to the first sampling tank, the first sampling tank is then connected to the second pipeline through the first sampling needle, the second pipeline fluid is connected to the outlet, the sampling pump is arranged on the first pipeline or the second pipeline, the second sampling needle includes a second embedded needle, a second outer liner, and a second interface component, one end of the second embedded needle is connected to the first pipeline outside the second sampling tank, and the other end extends to the bottom of the second sampling tank, the second interface component surrounds the second embedded needle and is connected to the top opening of the second sampling tank, the second outer liner extends from the second interface component and is connected to The first embedded needle of the first sampling needle, the first sampling needle includes a first embedded needle, a first outer liner, and a first interface component, one end of the first embedded needle is connected to the second outer liner outside the first sampling tank, and the other end extends to the bottom of the first sampling tank, the first interface component surrounds the first embedded needle and is connected to the top opening of the first sampling tank, the first outer liner extends from the first interface component and is connected to the second pipeline, a second front switch valve is arranged on the first pipeline, a second rear switch valve and a first front switch valve are arranged on the passage between the second sampling tank and the first sampling tank, the second rear switch valve is closer to the second sampling tank than the first front switch valve, the first rear switch valve is arranged on the second pipeline, the device starts to replace the sampling flow path, wherein the first front switch valve, the first rear switch valve, the second front switch valve, and the second rear switch valve are all opened, and the sampling port is fixedly connected to the connecting port The sampling pump presses the self-sampling gas pump into the sampling port. The sampling gas flows through the first pipeline and the second embedded needle and is sent to the bottom of the second sampling tank. The sampling gas forms a convection from bottom to top in the second sampling tank, thereby pushing the original gas in the second sampling tank from bottom to top through the second interface and out of the second outer liner. Subsequently, the original gas from the second sampling tank is pushed to the first embedded needle under the push of the sampling gas, and enters the first sampling tank through the first embedded needle, forming a bottom-up convection at the bottom of the first sampling tank, thereby pushing the original gas in the second sampling tank and the first sampling tank through the first interface and the first outer liner to leave the first sampling tank, and then discharged from the outlet along the second pipeline. Subsequently, the device switches to a pressurized sampling flow path, wherein the first rear switch valve is closed, and the sampling pump presses the sampling gas pump into the sampling port. The sampling gas flows through the first pipeline and then through the second embedded needle and is sent to the bottom of the second sampling tank. The sampling gas forms convection from bottom to top in the second sampling tank, thereby pushing the original gas in the second sampling tank from bottom to top through the second interface component and out of the second outer liner tube, thereby collecting the sampling gas in the second sampling tank, and then, the sampling gas in the second sampling tank gradually overflows from the bottom of the tank to the second embedded needle, and then flows along the second embedded needle into the first outer liner tube and the first interface component, and then flows into the first sampling tank, thereby collecting the sampling gas in the first sampling tank, and then, as the sampling gas in the first sampling tank and the second sampling tank is collected cumulatively, the sampling gas in the first and second sampling tanks gradually increases in pressure from the bottom of the tank, and when the pressure increases to a specific threshold, the first front switch valve, the second rear switch valve, and the second front switch valve are closed at the same time.

Preferably, the first sampling needle and the second sampling needle are inerted by molten silicon coating.

Preferably, a pressure gauge is installed on the first pipeline. As the pressure in the first and second sampling tanks gradually increases, the reading on the pressure gauge also gradually increases. Once the reading on the pressure gauge is greater than a specific threshold, the first front switch valve is first closed to complete the gas sampling of the first sampling tank and take out the first sampling tank. Then, the second rear switch valve and the second front switch valve are closed to complete the gas sampling of the second sampling tank and take out the second sampling tank.

Preferably, the first embedded needle penetrates into a position 2-5 cm away from the bottom of the first sampling tank.

Preferably, the second embedded needle penetrates into a position 2-5 cm away from the bottom of the second sampling tank.

In summary, in the jacketed needle type convection displacement positive pressure sampling device provided by the present invention, when performing gas replacement and gas sampling on the sampling tank, the sampling needle is used to probe the bottom of the sampling tank. The sampling needle is not only an indispensable link for the smooth flow of the airflow channel, but also cleverly forms convection in the sampling tank, thereby effectively removing the original gas in the sampling tank through the bottom-up convection effect during the gas replacement stage, thereby effectively cleaning the sampling tank and avoiding contamination of the sampling tank. Further, during the gas sampling stage, the presence of the sampling needle can serve as a current limiting buffer to ensure that the gas pressure rises in an orderly manner without causing an instantaneous pressure surge, thereby avoiding the sampling tank from being subjected to excessive pressure in a short period of time. Furthermore, the sampling needle also plays the role of a series connection. Through the series connection of the sampling needle, two or more sampling tanks are effectively connected in series, so that the parallel advancement and sample backup of two or more sampling tanks in terms of gas replacement and gas sampling can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be discussed below. Obviously, the technical solutions described in conjunction with the drawings are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments and their drawings can be obtained based on the embodiments shown in these drawings without paying creative work.

FIG1 shows a basic structural schematic diagram of a jacketed needle-type convection displacement positive pressure sampling device according to the present invention.

FIG. 2 shows the specific structure of the sampling needle in the jacketed needle type convection displacement positive pressure sampling device according to the present invention.

FIG3 shows a schematic diagram of the basic structure of two sampling cans arranged in the jacketed needle type convection displacement positive pressure sampling device according to the present invention.

Detailed ways

The technical solutions of various embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In short, the jacketed needle convection displacement positive pressure sampling device provided by the present invention can utilize the jacketed needle double-cavity air path structure and the pushing (pressure) force of the sampling pump to form a pressure difference at the top and bottom of the closed tank, thereby allowing the airflow inside the closed sample tank to quickly convect and completely replace the residual gas in the tank body, ensuring the accuracy of the collected samples, especially the trace gas components in the background air. At the same time, by switching the valve and the pump, the vacuum cleaning and pressurized sampling and storage of the tank body can be achieved, enhancing the versatility and practicality of the device.

Generally speaking, the device realizes the displacement sampling flow path and the pressurized sampling flow path in parallel with the same basic structure. The two flow paths appear at different times in the device, and are opposite to each other and complement each other. In the following, the displacement sampling flow path will be introduced first and the general structure of the device will be described in the process.

The main function of the replacement sampling flow path is to empty the original gas in the sampling tank and the pipeline connected to the sampling tank "as much as possible", so as to ensure that the gas finally sampled is the sampling gas that the detection party hopes to sample and reflects the on-site conditions to the greatest extent. The introduction of the replacement sampling flow path starts from Figure 1.

FIG1 shows a basic structural schematic diagram of a jacketed needle-type convection displacement positive pressure sampling device according to the present invention.

As shown in FIG. 1 , in the embodiment of FIG. 1 , the gas flow direction of the replacement sampling flow path is indicated by a thin arrow. In the replacement sampling flow path, the sampling port is connected to the sampling tank 103 through the first pipeline 101 and then through the sampling needle 102 fluid via the connection port 100 fixed thereto, and the sampling needle 102 is then connected to the outlet 105 through the second pipeline 104 fluid. Among them, a sampling pump 106 is arranged in the first pipeline 101 to control the flow direction of the gas flow.

It should be noted that the sampling pump 106 can be disposed in either the first pipeline 101 or the second pipeline 104 .

When the sampling flow path is replaced, the sampling pump 106 is turned on to pump out the sampled gas in the sampling port, and then the sampled gas flows through the first pipeline 101, flows through the sampling needle 102, and then flows into the sampling tank 103. After the sampled gas flows into the sampling tank 103, the gas in the sampling tank 103 is replaced, thereby removing the original gas in the sampling tank 103 as much as possible. Further, in the sampling tank 103, the original gas is blown by the sampled gas through the sampling needle 102 and then blown into the second pipeline 104 until it is blown out of the outlet 105.

The operation of the above-mentioned replacement sampling flow path ensures that the sampling tank and the first and second pipelines are thoroughly cleaned, and the residual amount of the original gas is reduced as much as possible.

As can be seen from the above description, the sampling needle 102 is used twice when the replacement sampling flow path is running, that is, the sample gas flows through the sampling needle when it flows into the sampling tank, and then flows through the sampling needle again when the original gas is blown out of the sampling tank.

Therefore, it is necessary to introduce the structure of the sampling needle 102. Fig. 2 shows the specific structure of the sampling needle in the jacket needle type convection displacement positive pressure sampling device according to the present invention.

First, it should be noted that the sampling needle 102 is preferably inertly coated with molten silicon to enhance relevant performance.

As shown in FIG2 , the sampling needle 102 includes an inner needle 102a, an outer liner 102b, and an interface 102c. One end of the inner needle 102 is connected to the first pipeline 101 outside the sampling tank 103, and the other end extends to the bottom of the sampling tank 103. The interface 102c surrounds the inner needle 102a and is connected to the top opening of the sampling tank 103. The outer liner 102b extends from the interface 102c and is connected to the second pipeline 104.

It can also be seen in Figures 1 and 2 that the switch valve 108 is divided into a front switch valve 108a and a rear switch valve 108b, the front switch valve 108a is arranged on the passage of the first pipeline 101, and the rear switch valve 108b is arranged on the passage of the second pipeline 104. When the replacement sampling flow path is in operation, the front switch valve 108a and the rear switch valve 108b are both opened. The operation of the switch valve 108 when the pressurized sampling flow path is in operation will be described in detail later.

Based on the structure described above, when the replacement sampling flow path is running, the front and rear switch valves 108a and 108b are both opened so as not to affect the smooth flow of the flow path. After the sampling gas pushed out by the pump flows through the first pipeline 101, it continues to flow under the guidance of the embedded needle 102a. Since the embedded needle 102a extends to the bottom of the sampling tank 103, the sampling gas flows into the bottom of the sampling tank 103 under the guidance of the embedded needle 102a. As a result, the sampling gas forms convection from bottom to top in the sampling tank 103. Through the effect of gas convection, the original gas in the sampling tank 103 is pushed from bottom to top through the interface 102c and flows out from the outer liner 102b. Subsequently, since the outer liner 102b is connected to the second pipeline 104, the gas flowing out of the outer liner 102b will be blown out of the outlet 105 through the second pipeline 104.

This setting of the sampling needle is very important for the present invention. As mentioned above, the embedded needle 102 extends to the bottom of the tank. In actual operation, for example, the embedded needle penetrates into a position 2-5 cm away from the bottom of the sampling tank. Through the action of the pump push (pressure) force, all the gas in the tank can be quickly circulated and extracted, thereby completely replacing the gas.

After the operation of the replacement sampling flow path is completed, the pressurized sampling flow path can be quickly switched. The pressurized sampling flow path is indicated by a bold arrow in Figure 1. In the pressurized sampling flow path, the rear switch valve 108b is first closed, thereby collecting the sample gas in the sampling tank 103.

As the air pressure in the sampling tank 103 continues to increase, the pressure of the sampled gas in the sampling tank 103 gradually increases from the bottom of the tank.

At this time, a pressure gauge 107 is installed on the passage of the first pipeline 101. Although the rear switch valve 108b on the second pipeline 104 is closed at this time, since the front switch valve 108a on the first pipeline 101 is still open, the first pipeline 101 and the sampling tank 103 are still connected. Therefore, the air pressure displayed on the pressure gauge 107 can still represent the air pressure in the sampling tank 103.

As the sample gas in the sampling tank 103 gradually increases in pressure from the bottom of the tank, the reading of the pressure gauge 107 also gradually increases. Once the reading in the pressure gauge is greater than a specific threshold, the front switch valve 108a is closed, thereby terminating the gas supply to the sampling tank 103. At this time, since the front and rear switch valves are closed, the sampling tank 103 will no longer be connected to the first pipeline 101 and the second pipeline 104, and the staff can calmly take away the sampling tank 103 for subsequent sample gas analysis.

FIG3 shows a schematic diagram of the basic structure of two sampling cans arranged in the jacketed needle type convection displacement positive pressure sampling device according to the present invention.

As shown in FIG3 , the sampling port is fixed to the connection port 100. When the sampling flow path is replaced, the sampling pump 106 is turned on to pump out the sampled gas in the sampling port, and then the sampled gas flows through the first pipeline 101, flows through the second embedded needle 202a of the second sampling needle 202, and then flows into the second sampling tank 203. After the sampled gas flows into the sampling tank 203, the gas in the second sampling tank 203 is replaced, thereby removing the original gas in the second sampling tank 203 as much as possible. Further, in the second sampling tank 203, the original gas is blown by the sampled gas through the second interface part 202c and the second outer liner 202b of the second sampling needle 202. So far, the configuration is similar to the embodiment shown in FIG1 .

The following flow path configuration begins to differ from the embodiment shown in FIG1 . In FIG3 , the second outer liner tube 202b will not be directly connected to the second pipeline 104 , and its gas flow is connected to the first sampling tank 103 . Specifically, the first sampling tank 103 is paired with a first sampling needle 102 , and the first sampling needle 102 includes a first embedded needle 102a , a first outer liner tube 102b , and a first interface component 102c . One end of the first embedded needle 102a is connected to the first outer liner tube 102b outside the first sampling tank 103 , and the other end extends to the bottom of the first sampling tank 103 . The first interface component 102c surrounds the first inner 102a and is connected to the top opening of the first sampling tank 103 . The first outer liner tube 102b extends from the first interface component 102c and is connected to the second pipeline 104 .

In addition, in Figure 3, a second front switch valve 208a is set on the first pipeline 101, and a second rear switch valve 208b and the first front switch valve 108a are set on the passage between the second sampling tank 203 and the first sampling tank 103. The second rear switch valve 208b is closer to the second sampling tank 203 than the first front switch valve 108a, and the first rear switch valve 108b is set on the second pipeline 104.

In this embodiment, the configuration surrounding the first sampling tank is basically the same as that of the second sampling tank, but the outlet of the first sampling tank (first outer liner) is connected to the inlet of the second sampling tank (second embedded needle), thereby connecting the first sampling tank and the second sampling tank in series, and the outlet of the second sampling tank (second outer liner) is connected to the second pipeline 104 as the outlet of the second sampling tank.

Therefore, in the embodiment of FIG. 3 , when the replacement sampling flow path is in operation, the above four switch valves are all opened, and the sampling gas pressed by the pump flows through the first pipeline 101, and then continues to flow under the guidance of the second embedded needle 202a. Since the second embedded needle 202a extends to the bottom of the second sampling tank 203, the sampling gas flows into the bottom of the second sampling tank 203 under the guidance of the first embedded needle 202a. As a result, the sampling gas forms convection from bottom to top in the second sampling tank 203. Through the gas convection effect, the original gas in the second sampling tank 203 is pushed from bottom to top through the second interface 202c and flows out of the second outer liner 202b. Subsequently, since the second outer liner tube 202b is connected to the first embedded needle 102a, the original gas is pushed toward the first embedded needle 102a by the push of the sampling gas, and enters the first sampling tank 103 through the first embedded needle 102a, forming a bottom-up convection at the bottom of the first sampling tank 103, thereby completely removing the original gas in the first sampling tank 103, and then the original gas leaves the first sampling tank 103 through the first interface part 102c and the first outer liner tube 102b under the further push of the sampling gas, and is then discharged from the outlet 105 along the second pipeline 104, thereby realizing the gas replacement of the two sampling tanks connected in series.

After the operation of the replacement sampling flow path is completed, it can be switched to the pressurized sampling flow path. The pressurized sampling flow path is indicated by a thick arrow in Figure 3. In the pressurized sampling flow path, it is only necessary to close the first rear switch valve 108b. At the same time, the sampling pump 106 blows the sampling gas from the sampling port into the second outer liner 202b of the second sampling needle 202 through the first pipeline 101, and then flows into the second sampling tank 203 from the tank top of the second sampling tank 203 through the second interface part 202c, thereby collecting the sampling gas in the second sampling tank 203.

As the air pressure in the second sampling tank 203 continues to increase, the sampling gas in the second sampling tank 203 gradually overflows from the bottom of the tank to the second embedded needle 202a, and then flows along the second embedded needle 202a into the first outer liner tube 102b and the first interface part 102c, and then flows into the first sampling tank 103, thereby collecting the sampling gas in the first sampling tank 103.

As the air pressure in the first sampling tank 103 continues to increase, the pressure of the sampled gas in the first sampling tank 103 gradually increases from the bottom of the tank.

At this time, in this embodiment, a pressure gauge 107 is installed on the first pipeline 101. As the pressure in the two sampling tanks gradually increases, the reading on the pressure gauge 107 also gradually increases. Once the reading in the pressure gauge 107 is greater than a specific threshold, the first front switch valve 108a, the second rear switch valve 208b and the second front switch valve 208a are closed at the same time, completing the gas sampling of the first sampling tank 103 and the second sampling tank 203.

Thus, the introduction of the embodiment shown in FIG1 and the embodiment shown in FIG3 is basically completed. In the embodiment shown in FIG1, when the sampling tank is subjected to gas replacement and gas sampling, the sampling needle is used to probe the bottom of the sampling tank. The sampling needle is not only an indispensable link for the smooth flow of the airflow channel, but also cleverly forms convection in the sampling tank, thereby effectively removing the original gas in the sampling tank through the bottom-up convection effect during the gas replacement stage, thereby effectively cleaning the sampling tank and avoiding contamination of the sampling tank. Furthermore, during the gas sampling stage, the presence of the sampling needle can serve as a buffer to ensure that the gas pressure rises in an orderly manner without causing an instantaneous pressure surge, thereby avoiding the sampling tank from being subjected to excessive pressure in a short period of time.

In the embodiment shown in FIG3 , the sampling needle not only plays the role shown in FIG1 , but also plays the role of series connection. Through the series connection of the sampling needle, the two sampling tanks are effectively connected in series, so that the two sampling tanks can be advanced in parallel in terms of gas replacement and gas sampling. It can be seen that in the embodiment shown in FIG3 , the sampling needle has more functions.

The above description is only an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims (9)

1. A jacketed needle type convection displacement positive pressure sampling device, characterized in that the device can realize the displacement sampling flow path and the pressurized sampling flow path, In the device, the connection port is connected to the sampling tank through the first pipeline and then through the sampling needle fluid, and the sampling tank is connected to the outlet through the second pipeline through the sampling needle, and the sampling pump is arranged on the first pipeline or the second pipeline, wherein the front switch valve is arranged on the passage of the first pipeline, and the rear switch valve is arranged on the passage of the second pipeline, The sampling needle comprises an embedded needle, an outer liner, and an interface. One end of the embedded needle is connected to the first pipeline outside the sampling tank, and the other end extends to the bottom of the sampling tank. The interface surrounds the embedded needle and is connected to the top opening of the sampling tank. The outer liner extends from the interface and is connected to the second pipeline. The device starts the replacement sampling flow path, wherein the front switch valve and the rear switch valve are both opened, the sampling port is fixedly connected to the connecting port, the sampling pump presses the self-sampling gas pump into the sampling port, the sampling gas flows through the first pipeline and then flows through the embedded needle and is sent to the bottom of the sampling tank, the sampling gas forms convection from bottom to top in the sampling tank, thereby pushing the original gas in the sampling tank from bottom to top through the interface component and out of the outer liner, thereby the original gas is blown out of the outlet through the second pipeline together with the sampling gas; Subsequently, the device switches to a pressurized sampling flow path, wherein the rear switch valve is closed, thereby allowing the sampling gas from the sampling port to enter the connecting port, and the sampling gas flows through the first pipeline and then through the embedded needle to be blown into the sampling tank, thereby collecting and accumulating the sampling gas in the sampling tank, and the pressure of the sampling gas in the sampling tank gradually increases from the bottom of the tank, and when the pressure increases to a specific threshold, the front switch valve is closed. 2. The device according to claim 1 is characterized in that the sampling needle is inertly coated with molten silicon. 3. The device according to claim 1 is characterized in that a pressure gauge is installed on the passage of the first pipeline. During the operation of the pressurized sampling flow path, the reading in the pressure gauge gradually increases. Once the reading in the pressure gauge is greater than a specific threshold, the front switch valve is closed, causing the front switch valve and the rear switch valve to be closed, thereby terminating the gas supply to the sampling tank. 4. The device according to claim 1 is characterized in that the embedded needle penetrates into a position 2-5 cm away from the bottom of the sampling tank. 5. A jacketed needle type convection displacement positive pressure sampling device, characterized in that the device can realize the displacement sampling flow path and the pressurized sampling flow path, In the device, the connecting port is connected to the second sampling tank via the first pipeline and then the second sampling needle fluid, the second sampling needle is connected to the first sampling needle via the first sampling needle, the first sampling needle is connected to the first sampling tank, the first sampling tank is connected to the second pipeline via the first sampling needle, the second pipeline fluid is connected to the outlet, and the sampling pump is arranged on the first pipeline or the second pipeline. The second sampling needle comprises a second embedded needle, a second outer liner, and a second interface member. One end of the second embedded needle is connected to the first pipeline outside the second sampling tank, and the other end extends to the bottom of the second sampling tank. The second interface member surrounds the second embedded needle and is connected to the top opening of the second sampling tank. The second outer liner extends from the second interface member and is connected to the first embedded needle of the first sampling needle. The first sampling needle comprises a first embedded needle, a first outer liner, and a first interface member. One end of the first embedded needle is connected to the second outer liner outside the first sampling tank, and the other end extends to the bottom of the first sampling tank. The first interface member surrounds the first embedded needle and is connected to the top opening of the first sampling tank. The first outer liner extends from the first interface member and is connected to the second pipeline. A second front switch valve is arranged on the first pipeline, a second rear switch valve and the first front switch valve are arranged on the passage between the second sampling tank and the first sampling tank, the second rear switch valve is closer to the second sampling tank than the first front switch valve, and the first rear switch valve is arranged on the second pipeline, The device starts the replacement sampling flow path, wherein the first front switch valve, the first rear switch valve, the second front switch valve, and the second rear switch valve are all opened, the sampling port is fixedly connected to the connecting port, and the sampling pump presses the self-sampling gas pump into the sampling port. The sampling gas flows through the first pipeline and the second embedded needle and is sent to the bottom of the second sampling tank. The sampling gas forms convection from bottom to top in the second sampling tank, thereby pushing the original gas in the second sampling tank from bottom to top through the second interface component and out of the second outer liner tube. Subsequently, the original gas from the second sampling tank is pushed toward the first embedded needle by the sampling gas, and enters the first sampling tank through the first embedded needle, forming a bottom-up convection at the bottom of the first sampling tank, thereby pushing the original gas in the second sampling tank and the first sampling tank through the first interface member and the first outer liner to leave the first sampling tank, and then discharged from the outlet along the second pipeline. Subsequently, the device is switched to a pressurized sampling flow path, wherein the first rear switch valve is closed, and the sampling pump presses the sampling gas into the sampling port. The sampling gas flows through the first pipeline and then flows through the second embedded needle and is sent to the bottom of the second sampling tank. The sampling gas forms a convection from bottom to top in the second sampling tank, thereby pushing the original gas in the second sampling tank from bottom to top through the second interface member and out of the second outer liner tube, thereby collecting the sampling gas in the second sampling tank. Then, the sampled gas in the second sampling tank gradually overflows from the tank bottom to the second embedded needle, and then flows along the second embedded needle into the first outer liner tube and the first interface member, and then flows into the first sampling tank, thereby collecting the sampled gas in the first sampling tank. Subsequently, as the sampled gas in the first sampling tank and the second sampling tank is collected and accumulated, the pressure of the sampled gas in the first and second sampling tanks gradually increases from the bottom of the tank. When the pressure increases to a specific threshold, the first front switch valve, the second rear switch valve, and the second front switch valve are closed at the same time. 6 . The device according to claim 5 , wherein the first sampling needle and the second sampling needle are inerted by molten silicon coating. 7. The device according to claim 5 is characterized in that a pressure gauge is installed on the first pipeline. As the pressure in the first and second sampling tanks gradually increases, the reading on the pressure gauge also gradually increases. Once the reading in the pressure gauge is greater than a specific threshold, the first front switch valve is first closed to complete the gas sampling of the first sampling tank and take out the first sampling tank. Then, the second rear switch valve and the second front switch valve are closed to complete the gas sampling of the second sampling tank and take out the second sampling tank. 8. The device according to claim 5, characterized in that the first embedded needle penetrates into a position 2-5 cm away from the bottom of the first sampling tank. 9. The device according to claim 5, characterized in that the second embedded needle penetrates into a position 2-5 cm away from the bottom of the second sampling tank.