Automatic replacement device for fluorine-nitrogen mixed gas analysis

Abstract

According to the automatic replacement device for fluorine-nitrogen mixed gas analysis provided by the utility model, the valves, the vacuum pump, the heating unit and the first analysis instrument are respectively controlled by the control unit, and the valves are matched with one another to be opened and closed before sample gas enters the first analysis instrument; the purging gas and the oxygen enter the device to be replaced, it is ensured that the device has the leakproofness, gas in all the pipelines, the first buffer tank and the first analysis instrument is fully purged, the analysis accuracy is improved, meanwhile, a valve switch does not need to be manually operated, and the safety coefficient is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a chemical industry technical field especially relates to a fluorine nitrogen mixed gas analysis automatic replacement device. BACKGROUND

[0002] Fluorine nitrogen mixed gas (F2-N2) is the important raw material of atomic energy industry, fluorine-containing electronic special gas, pharmaceutical intermediates and so on, is also the ideal material of some special material surface modification, for example, the production of integrated circuit and various electronic components, the cleaning of CVD chamber in semiconductor manufacturing process, and the accurate monitoring of fluorine nitrogen gas ratio content and each impurity is particularly important for the subsequent use of product.

[0003] The traditional F2-N2 analysis sample adopts direct connection analysis instrument, but this mode is not convenient for analysis pipeline replacement, sample gas purging, and is not convenient for back-end analysis instrument flow control and protection.

[0004] In the prior art, air in the pipeline is sucked into the venturi tube to achieve gas replacement, for example, a fluorine-containing gas analysis device disclosed in patent publication No. 220961459U, comprising a first passage, a second passage, a third passage and a fourth passage; The ordinary nitrogen gas inlet pipeline, the first pressure reducing valve, the first pressure gauge, the first valve, the check valve and the venturi tube are sequentially arranged on the first passage, and the inlet of the ordinary nitrogen gas inlet pipeline, the first pressure reducing valve, the first pressure gauge, the first valve, the check valve and the venturi tube are connected by a pipeline; The second passage includes fluorine gas inlet pipeline, sixth valve, fourth valve, second pressure reducing valve, second pressure gauge, seventh valve and analysis instrument arranged in sequence. The scheme is simple and convenient to operate, and has high controllability and safety performance. The air in the pipeline is sucked into the venturi tube through the venturi tube, and then the air is discharged from the outlet of the venturi tube. The scheme can replace the gas in the device to a certain extent, but the effect is limited. The traditional analysis method needs manual valve operation. Due to the characteristics of fluorine gas, there is a risk of overflow, which may cause safety accidents. Therefore, it is necessary to provide a F2-N2 analysis replacement device capable of realizing automatic replacement. UTILITY MODEL CONTENTS

[0005] Therefore, it is necessary to provide a fluorine nitrogen mixed gas analysis automatic replacement device to solve the problem.

[0006] To achieve the above purpose, the utility model provides a fluorine nitrogen mixed gas analysis automatic replacement device, comprising:

[0007] The first gas inlet pipeline is used for inputting sample gas to be analyzed, and the gas inlet end is connected to the sample gas source. The first gas inlet pipeline is provided with a first gas inlet valve and a second gas inlet valve in sequence from the gas inlet end to the gas outlet end.

[0008] The second air inlet pipe is used to input purge gas to purge the sample gas in the device. Its inlet end is connected to the purge gas source, and its outlet end is connected to the first air inlet pipe between the first air inlet valve and the second air inlet valve. The second air inlet pipe is equipped with a third air inlet valve.

[0009] The air extraction pipeline has one end connected to the second air intake pipeline between the third air intake valve and the second air intake valve, and the other end connected to the vacuum pump. The air extraction pipeline is equipped with an air extraction valve, and the front end of the air extraction valve is equipped with a third pressure sensor.

[0010] The first buffer tank and the first analytical instrument have their air inlet connected to the air outlet of the first air inlet pipeline, and their air outlet connected to the air inlet of the first analytical instrument through the first analytical input pipeline and the first analytical input valve. The air outlet of the first analytical instrument is connected to the air extraction pipeline between the air extraction valve and the third pressure sensor through the first analytical output pipeline and the first analytical output valve. The first buffer tank is equipped with a first pressure sensor and a first heating unit.

[0011] The control unit is electrically connected to the first intake valve, the second intake valve, the third intake valve, the suction valve, the first analysis input valve, the first analysis output valve, the third pressure sensor, the first pressure sensor, the vacuum pump, the first heating unit, and the first analytical instrument.

[0012] Furthermore, it also includes a second buffer tank and a second analytical instrument. The second buffer tank is equipped with a second pressure sensor. The air inlet of the second buffer tank is connected to the second air inlet pipe between the second and third air inlet valves via a third air inlet pipe and a fourth air inlet valve. The air outlet of the second buffer tank is connected to the air inlet of the second analytical instrument via a second analytical input pipe and a second analytical input valve. The air outlet of the second analytical instrument is connected to the suction pipe between the suction valve and the third pressure sensor via a second analytical output pipe and a second analytical output valve. The second buffer tank is equipped with a second pressure sensor and a heating unit. The second analytical instrument, the second pressure sensor, the second analytical input valve, the second analytical output valve, and the second heating unit are electrically connected to the control unit.

[0013] Furthermore, it also includes a first manual valve, which is disposed at the front end of the first intake valve; and / or

[0014] It also includes a second manual valve, which is located at the rear end of the second intake valve; and / or

[0015] It also includes a third manual valve, which is located at the front end of the third intake valve; and / or

[0016] It also includes a fourth manual valve, which is located at the rear end of the fourth intake valve.

[0017] Further, the one-way valves are provided on one or more of the gas extraction pipeline at the front end of the gas extraction valve, the first analysis output pipeline at the rear end of the first analysis output valve, or the second analysis output pipeline at the rear end of the second analysis output valve.

[0018] Further, the tail gas absorption container is connected to the outlet of the vacuum pump.

[0019] Further, the first manual valve, the second manual valve, the third manual valve, the fourth manual valve, the first inlet valve, the second inlet valve, the third inlet valve, the gas extraction valve, the first analysis input valve, the first analysis output valve, the second analysis input valve, the second analysis output valve, and the one-way valves are made of fluorine-resistant materials.

[0020] Further, the first manual valve, the second manual valve, the third manual valve, and the fourth manual valve are ball valves, stop valves, gate valves, or butterfly valves; and / or

[0021] The first inlet valve, the second inlet valve, the third inlet valve, the gas extraction valve, the first analysis input valve, the first analysis output valve, the second analysis input valve, and the second analysis output valve are pneumatic valves or solenoid valves.

[0022] Further, the first buffer tank and the second buffer tank are provided with filter screens and heat insulation sleeves.

[0023] Unlike the prior art, the above technical solution controls each valve, the vacuum pump, the heating unit, and the first analysis instrument through the control unit, uses the opening and closing cooperation between each valve to make the purge gas and oxygen enter the device for replacement before the sample gas enters the first analysis instrument, ensures the airtightness of the device, fully purges the gas in each pipeline, the first buffer tank, and the first analysis instrument, improves the analysis accuracy, and eliminates the need for manual operation of the valve switch, thereby improving the safety factor. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The device structure schematic diagram for the specific implementation is described.

[0025] Figure 2 The device structure schematic diagram for another specific implementation is described, which is provided with a second buffer tank and a second analysis instrument.

[0026] Figure 3 The device structure schematic diagram for another specific implementation is described, which is provided with a first manual valve, a second manual valve, a third manual valve, and a fourth manual valve.

[0027] Figure 4 The device structure schematic diagram for another specific implementation is described, which is provided with a one-way valve.

[0028] Figure 5 Fig. 1 is a schematic diagram of the device for another embodiment.

[0029] Explanation of Reference Signs:

[0030] 11, first intake line; 12, second intake line; 13, third intake line; 14, exhaust line; 15, first analysis input line; 16, first analysis output line; 17, second analysis input line; 18, second analysis output line; 21, first intake valve; 22, second intake valve; 23, third intake valve; 24, fourth intake valve; 25, first analysis input valve; 26, first analysis output valve; 27, second analysis input valve; 28, second analysis output valve; 29, exhaust valve; 30, vacuum pump; 31, first manual valve; 32, second manual valve; 33, third manual valve; 34, fourth manual valve; 41, first pressure sensor; 42, second pressure sensor; 43, third pressure sensor; 50, control unit; 51, first buffer tank; 52, first analysis instrument; 53, second buffer tank; 54, second analysis instrument; 55, check valve; 56, exhaust absorption container. DETAILED DESCRIPTION

[0031] In order to make the technical contents, structural features, and purposes and effects of the technical solutions more clear, the following will be described in detail in combination with specific embodiments and the accompanying drawings.

[0032] In this document, the term "embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, and does not particularly limit the independence or association between other embodiments. In principle, in this application, as long as there is no technical contradiction or conflict, each technical feature mentioned in each embodiment can be combined in any way to form a corresponding implementable technical solution.

[0033] Unless otherwise defined, the meanings of the technical terms used in this document are the same as those commonly understood by those skilled in the art to which the present application belongs; the use of related terms in this document is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0034] In the description of the present application, the phrase "and / or" is used to describe the logical relationship between the objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this document generally represents a "or" logical relationship between the associated objects.

[0035] In the present application, the terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual number, primary or secondary, or order relationship between the entities or operations.

[0036] In the present application, the "includes", "contains", "has", or other similar expressions used in the statements are intended to cover non-exclusive inclusion, and do not exclude the presence of additional elements in the process, method or product comprising the elements, so that the process, method or product comprising a series of elements can not only include those defined elements, but also include other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0037] As the same understanding as in the "Guidelines for Examination", in the present application, the expressions such as "greater than", "less than", "exceed" are understood as not including the number; the expressions such as "above", "below", "within" are understood as including the number. In addition, in the description of the embodiments of the present application, the meaning of "multiple" is more than two (including two), and similar expressions related to "multiple" are also understood in this way, for example, "multiple groups", "multiple times", etc., unless otherwise explicitly specified.

[0038] In the description of the embodiments of the present application, the spatial-related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "perpendicular", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. The indicated orientation or position relationship is based on the orientation or position relationship shown in the specific embodiment or the drawing, and is only for the convenience of describing the specific embodiments of the present application or for the reader to understand, and does not indicate or imply that the indicated device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0039] Unless otherwise explicitly specified or limited, in the description of the embodiments of the present application, the terms "mount", "connect", "connect", "fix", "set", etc. should be understood in a broad sense. For example, the "connection" can be a fixed connection, or a detachable connection, or an integral setting; it can be a mechanical connection, or an electrical connection, or a communication connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art to which the present application belongs, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0040] Please refer toFigures 1 to 5 The embodiment provides a fluorine-nitrogen mixed gas analysis automatic replacement device.

[0041] The first gas inlet pipeline 11 is made of stainless steel and is used for inputting sample gas to be analyzed. The sample gas to be analyzed is fluorine-nitrogen mixed gas. The gas inlet end of the first gas inlet pipeline 11 is connected to a sample gas source. The first gas inlet pipeline 11 is sequentially provided with a first gas inlet valve 21 and a second gas inlet valve 22 from the gas inlet end to the gas outlet end.

[0042] The second gas inlet pipeline 12 is made of stainless steel and is used for inputting purge gas. The purge gas is used for clearing residual sample gas in the device to avoid affecting the analysis result. The purge gas can be high-purity nitrogen gas with a purity of 99.999%. The purge gas is used for purging the sample gas in the device. The gas inlet end of the second gas inlet pipeline 12 is connected to a purge gas source. The gas outlet end of the second gas inlet pipeline 12 is connected to the first gas inlet pipeline 11 between the first gas inlet valve 21 and the second gas inlet valve 22. The second gas inlet pipeline 12 is provided with a third gas inlet valve 23.

[0043] The gas extraction pipeline 14 is made of stainless steel. One end of the gas extraction pipeline 14 is connected to the second gas inlet pipeline 12 between the third gas inlet valve 23 and the second gas inlet valve 22. The other end of the gas extraction pipeline 14 is connected to a vacuum pump 30. The gas extraction pipeline 14 is provided with a gas extraction valve 29. The front end of the gas extraction valve 29 is provided with a third pressure sensor 43.

[0044] The first buffer tank 51 and the first analysis instrument 52 are connected to the gas outlet end of the first gas inlet pipeline 11 through the gas inlet. The gas outlet of the first analysis instrument 52 is connected to the gas extraction pipeline 14 between the gas extraction valve 29 and the third pressure sensor 43 through the first analysis output pipeline 16 and the first analysis output valve 26. The first buffer tank 51 is provided with a first pressure sensor 41 and a first heating unit. The first heating unit can be a resistance heating type. The resistance rod is heated quickly by applying voltage to achieve the effect of heating gas. The first heating unit can also be a heating coil. The coil is installed in the first buffer tank 51. The coil is connected to a heat transfer medium such as oil or steam to transfer heat and heat the sample gas in the tank. The first heating unit can also be a heating jacket. The jacket is installed on the outer wall of the tank. The jacket is connected to a heat transfer medium such as hot water, steam or hot oil to achieve uniform heating. The first analysis input pipeline 15 and the first analysis output pipeline 16 are made of stainless steel.

[0045] A control unit 50, which can be a PLC controller or a PC, whose operating system is known in the art, is provided to control the various components of the system. The control unit 50 is electrically connected to the first inlet valve 21, the second inlet valve 22, the third inlet valve 23, the exhaust valve 29, the first analysis input valve 25, the first analysis output valve 26, the third pressure sensor 43, the first pressure sensor 41, the vacuum pump 30, the first heating unit, and the first analysis instrument 52.

[0046] In the present embodiment, the operation flow is as follows: starting with the default state that all valves are closed. The following operations can be remotely controlled by the control unit 50. First, open the second inlet valve 22, the third inlet valve 23 and the first analysis input valve 25, and high-purity nitrogen gas enters the first buffer tank 51 and the first analysis instrument 52 through the second inlet pipeline 12 and the first inlet pipeline 11 in turn. After waiting for the high-purity nitrogen gas to fill the entire displacement device, when the first pressure sensor 41 and the third pressure sensor 43 both show positive pressure and the pressure is stable at a certain value (adjust according to the actual situation, and the pressure value in the present embodiment can be referred to as 0.3 MPa), close the third inlet valve 23, and after monitoring that the pressure value remains stable for a period of time (for example, 3 minutes), proceed to the next step; after completing the foregoing steps, perform system tightness confirmation, close the third inlet valve 23, open the air exhaust valve 29, and start the vacuum pump 30 to exhaust the high-purity nitrogen gas in the device to form a vacuum. The evacuation pressure can be -0.099 MPa. After monitoring that the pressure of the first pressure sensor 41 and the third pressure sensor 43 remains stable for a period of time (for example, 60 seconds), the system tightness confirmation is completed. After completing the system tightness confirmation, the device needs to be purged and replaced. The specific operation is as follows: close all valves, then open the third inlet valve 23, fill with high-purity nitrogen gas, close the third inlet valve 23, open the air exhaust valve 29 and the vacuum pump 30, and exhaust the high-purity nitrogen gas. Complete one purge and replacement, and repeat the purge and replacement several times, for example, thirty times. After completing the replacement, close all valves, open the first inlet valve 21 and the second inlet valve 22, and sample gas is filled into the first buffer tank 51 through the first inlet pipeline 11. Control the first heating unit to heat the sample gas in the first buffer tank 51 to greater than 100°C. In this step, the heating temperature of the first heating unit can be set to 150±5°C to ensure that the temperature of the sample gas in the first buffer tank 51 meets the requirements. When the values of the first pressure sensor 41 and the third pressure sensor 43 remain stable at 0.3 MPa for a period of time (for example, 3 minutes) without change, close the first inlet valve 21, open the air exhaust valve 29 and the vacuum pump 30, and perform sample gas replacement. After monitoring that the values of the first pressure sensor 41 and the third pressure sensor 43 remain stable at -0.099 MPa for a period of time (for example, 60 seconds) without change, close the air exhaust valve 29 and the vacuum pump 30, and repeat the sample gas replacement operation several times (for example, 5 times). After completing the sample gas replacement, open the first analysis input valve 25 and the first analysis output valve 26, and the sample gas enters the first analysis instrument 52 through the first analysis input pipeline 15. After analysis, the sample gas exits the first analysis instrument 52 through the first analysis output pipeline 16. Thus, one analysis is completed.

[0047] The new type controls each valve and the vacuum pump 30, the heating unit and the first analysis instrument 52 respectively through the control unit 50, uses the opening and closing cooperation between each valve, makes the purge gas and oxygen enter the device for replacement before the sample gas enters the first analysis instrument 52, ensures that the device has airtightness, and fully purges the gas in each pipeline, the first buffer tank 51 and the first analysis instrument 52, improves the analysis accuracy, and at the same time, does not need manual operation of the valve switch, improves the safety factor.

[0048] In some embodiments, a second buffer tank 53 and a second analysis instrument 54 are further included, the second buffer tank 53 is provided with a second pressure sensor 42; the gas inlet of the second buffer tank 53 is connected to the second gas inlet pipe 12 between the second gas inlet valve 22 and the third gas inlet valve 23 through the third gas inlet pipe 13 and the fourth gas inlet valve 24; the gas outlet of the second buffer tank 53 and the gas inlet of the second analysis instrument 54 are communicated through the second analysis input pipe 17 and the second analysis input valve 27, the gas outlet of the second analysis instrument 54 is connected to the exhaust pipe 14 between the exhaust valve 29 and the third pressure sensor 43 through the second analysis output pipe 18 and the second analysis output valve 28, the second buffer tank 53 is provided with a second pressure sensor 42 and a heating unit; the second analysis instrument 54, the second pressure sensor 42, the second analysis input valve 27, the second analysis output valve 28 and the second heating unit are electrically connected with the control unit 50 respectively.

[0049] The second buffer tank 53 and the first buffer tank 51, the second analysis instrument 54 and the first analysis instrument 52 are the same structure respectively. The working principle can refer to the first buffer tank 51 and the first analysis instrument 52, by setting the second buffer tank 53 and the second analysis instrument 54, the replacement, purging and analysis work can be carried out at the same time, by comparing the analysis results of the first analysis instrument 52 and the second analysis instrument 54, the accuracy of sample gas analysis is improved, and the error is reduced.

[0050] To further improve the safety of the first, second or third gas inlet pipeline 11, 12 or 13, in some embodiments, a first manual valve is provided at the front end of the first gas inlet valve 21, and / or a second manual valve 32 is provided at the rear end of the second gas inlet valve 22, and / or a third manual valve 33 is provided at the front end of the third gas inlet valve 23, and / or a fourth manual valve 34 is provided at the rear end of the fourth gas inlet valve 24. Before starting the work, manually open the first, second, third and fourth manual valves 31, 32, 33 and 34, and after the work is completed, manually close the first, second, third and fourth manual valves 31, 32, 33 and 34, to provide additional valves and pipeline safety redundancy, and improve the safety factor.

[0051] In some embodiments, one-way valves 55 are also included, which are provided at one or more locations on the gas extraction pipeline 14 in front of the gas extraction valve 29, on the first analysis output pipeline 16 behind the first analysis output valve 26, or on the second analysis output pipeline 18 behind the second analysis output valve 28. By providing one-way valves 55, gas backflow can be avoided, ensuring the completion of displacement and purging work.

[0052] In some embodiments, a tail gas absorption container 56 is also included, with its gas inlet connected to the gas outlet of the vacuum pump 30. The tail gas absorption container 56 can be provided with an absorption liquid, which can be water, hydrofluoric acid, fluorosilicic acid, sodium carbonate, ammonium hydroxide, ammonium fluoride, calcium hydroxide, sodium chloride, potassium sulfate, etc. By connecting the tail gas absorption container 56 to the rear end of the vacuum pump 30, the absorption liquid can absorb fluorine gas, preventing fluorine gas from escaping and causing safety hazards.

[0053] In some embodiments, the first, second, third and fourth manual valves 31, 32, 33 and 34, the first, second and third gas inlet valves 21, 22 and 23, the gas extraction valve 29, the first and second analysis input valves 25 and 27, the first and second analysis output valves 26 and 28, and the one-way valves 55 are made of fluorine-resistant materials. Fluorine-resistant materials can be polytetrafluoroethylene (PTFE), polytetrafluoroethylene (FEP), polyvinylidene fluoride (PVDF), polytrifluoroethylene (PCTFE), etc. This ensures that the valves are not eroded by fluorine gas and that the device remains airtight.

[0054] In some embodiments, the first manual valve, the second manual valve 32, the third manual valve 33 and the fourth manual valve 34 are ball valves, stop valves, gate valves or butterfly valves. Among them, the ball valve is preferred, and the structure of the ball valve mainly consists of a valve body, a ball, a valve rod and a sealing element. The opening and closing part of the ball valve is a ball, which is driven by a valve rod and rotates around the ball valve axis to realize opening and closing. The ball valve has compact structure, the sealing surface and the ball surface are often in closed state, and it is not easy to be eroded by medium, and it is convenient to operate and maintain.

[0055] In some embodiments, the first air inlet valve 21, the second air inlet valve 22, the third air inlet valve 23, the air extraction valve 29, the first analysis input valve 25, the first analysis output valve 26, the second analysis input valve 27 and the second analysis output valve 28 are pneumatic valves or electromagnetic valves. Among them, the pneumatic valve is preferred, and the pneumatic valve mainly includes a pneumatic actuator, a valve positioner, a valve body and a valve core. The pneumatic valve is driven by compressed air, does not need complex electrical connection, has relatively simple structure, high safety, can realize remote control and is not affected by pipeline delivery pressure.

[0056] In some embodiments, the first buffer tank 51 and the second buffer tank 53 are both provided with a filter screen and a heat preservation sleeve. The filter screen can be made of stainless steel, and the mesh number can be 100 meshes. The filter screen can filter impurities in the sample gas to avoid damage after entering the first analysis instrument 52. The heat preservation sleeve is made of high temperature resistant material, such as glass fiber, ceramic fiber, rock wool, polyurethane foam plastic and the like, and the lower limit of its temperature resistance is 160℃.

[0057] It should be noted that although the above embodiments have been described in this paper, the patent protection scope of the utility model is not limited thereby. Therefore, based on the innovative idea of the utility model, the changes and modifications of the embodiments described in this paper, or the equivalent structure or equivalent process transformation made by using the contents of the utility model specification and drawings, directly or indirectly apply the above technical solutions to other related technical fields, are all included in the protection scope of the patent of the utility model.

Claims

1. An automatic replacement device for analyzing fluorine-nitrogen mixed gas, characterized in that, The device comprises: a first gas inlet pipeline for inputting sample gas to be analyzed, the gas inlet end of which is connected to a sample gas source, and a first gas inlet valve and a second gas inlet valve are arranged on the first gas inlet pipeline in sequence from the gas inlet end to the gas outlet end; a second gas inlet pipeline for inputting purge gas to purge the sample gas in the device, the gas inlet end of which is connected to a purge gas source, and the gas outlet end is connected to the first gas inlet pipeline between the first gas inlet valve and the second gas inlet valve, and a third gas inlet valve is arranged on the second gas inlet pipeline; an exhaust pipeline, one end of which is connected to the second gas inlet pipeline between the third gas inlet valve and the second gas inlet valve, and the other end is connected to a vacuum pump, and an exhaust valve is arranged on the exhaust pipeline, and a third pressure sensor is arranged at the front end of the exhaust valve; a first buffer tank and a first analysis instrument, the gas inlet of the first buffer tank is connected to the gas outlet end of the first gas inlet pipeline, the gas outlet of the first buffer tank is connected to the gas inlet of the first analysis instrument through a first analysis input pipeline and a first analysis input valve, the gas outlet of the first analysis instrument is connected to the exhaust pipeline between the exhaust valve and the third pressure sensor through a first analysis output pipeline and a first analysis output valve, and a first pressure sensor and a first heating unit are arranged on the first buffer tank; a control unit, which is electrically connected to the first gas inlet valve, the second gas inlet valve, the third gas inlet valve, the exhaust valve, the first analysis input valve, the first analysis output valve, the third pressure sensor, the first pressure sensor, the vacuum pump, the first heating unit, and the first analysis instrument.

2. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 1, characterized in that: The device further comprises a second buffer tank and a second analysis instrument, a second pressure sensor is arranged on the second buffer tank, the gas inlet of the second buffer tank is connected to the second gas inlet pipeline between the second gas inlet valve and the third gas inlet valve through a third gas inlet pipeline and a fourth gas inlet valve, the gas outlet of the second buffer tank is connected to the gas inlet of the second analysis instrument through a second analysis input pipeline and a second analysis input valve, the gas outlet of the second analysis instrument is connected to the exhaust pipeline between the exhaust valve and the third pressure sensor through a second analysis output pipeline and a second analysis output valve, a second pressure sensor and a heating unit are arranged on the second buffer tank, and the second analysis instrument, the second pressure sensor, the second analysis input valve, the second analysis output valve, and the second heating unit are electrically connected to the control unit.

3. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 2, characterized in that: The device further comprises a first manual valve arranged at the front end of the first gas inlet valve; and / or The device further comprises a second manual valve arranged at the rear end of the second gas inlet valve; and / or The device further comprises a third manual valve arranged at the front end of the third gas inlet valve; and / or The device further comprises a fourth manual valve arranged at the rear end of the fourth gas inlet valve.

4. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 3, characterized in that: The device further comprises one or more one-way valves arranged on the exhaust pipeline at the front end of the exhaust valve, on the first analysis output pipeline at the rear end of the first analysis output valve, or on the second analysis output pipeline at the rear end of the second analysis output valve.

5. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 4, characterized in that: The device further comprises a tail gas absorption container, the gas inlet of which is connected to the gas outlet of the vacuum pump.

6. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 5, characterized in that: The first manual valve, the second manual valve, the third manual valve, the fourth manual valve, the first air inlet valve, the second air inlet valve, the third air inlet valve, the air outlet valve, the first analysis input valve, the first analysis output valve, the second analysis input valve, the second analysis output valve and the one-way valve are made of fluorine-resistant material.

7. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 5, characterized in that: The first manual valve, the second manual valve, the third manual valve and the fourth manual valve are ball valves, stop valves, gate valves or butterfly valves; and / or The first air inlet valve, the second air inlet valve, the third air inlet valve, the air outlet valve, the first analysis input valve, the first analysis output valve, the second analysis input valve and the second analysis output valve are pneumatic valves or solenoid valves.

8. The automatic replacement device for analyzing mixed gas of fluorine and nitrogen according to claim 5, characterized in that: The first buffer tank and the second buffer tank are both provided with a filter screen and a heat preservation sleeve.

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