A system and method for continuous and automatic preparation of trace gases

Abstract

A system and method for continuous and automatic preparation of trace gases, field of trace gas preparation. The system of the present invention includes a main gas control unit, a trace gas control unit, a balance gas control unit, a switching valve unit, a gas mixing unit, and a delivery control unit. The method for continuous and automatic preparation of trace gases of the present invention adopts a quantitative ring to supply a quantitative trace gas to an air bag with a quantitative main component gas, and after mixing, further continuous gas mixing is performed by continuous fixed-proportion gas distribution. The present invention has strong adaptability and is conducive to the continuous connection of gas components used in experiments or production, including different types. It can reduce the inflexibility and waste of the small amount of gas required by the volumetric method in the comparison technology and the need for a large amount of gas preparation, and can also avoid the problem of interruption caused by the change of components in the continuous method and the need to replace the damping capillary.

Description

Technical Field

[0001] The invention belongs to the field of trace gas preparation, and in particular relates to a system and method for continuous and automatic preparation of trace gases. Background Art

[0002] The preparation of trace gases generally refers to the composition ratio of the target component in the total gas with a content of mmol / mol or even below μmol / mol. Trace gas preparation technology is widely used and has become a common application technology in conventional chemical reactions, fuel cells, environmental testing, agricultural planting, atmospheric simulation, precision electronics, medical and biological fields. There are five main methods for trace gas preparation, namely weight method, pressure ratio method, mass flow ratio method, static volume method and permeation tube method, among which the first three are more widely used.

[0003] Due to the improvement of application requirements and the imperfection of technology, many attempts to provide convenient, fast and accurate gas distribution technologies have emerged in recent years.

[0004] For example, patents CN102698645B and CN102921338B use single-stage or multi-stage fixed-volume containers, add different gases and mix and test, and then adjust the ratio to achieve the set ratio. This method is intermittent and requires at least a relatively large total volume to be used. Patent CN104162372B provides a water-gas replacement technology, which is an intermittent supply and does not have convenient conditions for large flow control. It requires the environment receiving the gas to maintain precise pressure stability, otherwise rapid volume changes will automatically occur, causing a large change in the output flow rate, including back suction.

[0005] Patents CN104248919B and CN211913375U use damping tubes to provide stable flow control for trace gases in the mix. Setting and changing the length of the damping tube requires detection and verification, which is not convenient in application and does not have the ability to automatically and quickly change components. CN104303126B provides molecular weight change measurement to achieve the purpose of adjusting the mix, but is not applicable to gases with similar molecular weights or small addition ratios.

[0006] Patent CN201711444272.0 uses a cavitation mixer, which has the advantages of continuous air supply and relatively good mixing effect, but is limited by the jet principle, and its flow range and ratio are subject to certain restrictions.

[0007] Patent CN104785134B provides an isobaric gas proportioning method, which is suitable for gas proportioning with similar flow rates. Patent CN104959049B provides a large-ratio gas proportioning technology, but the weighing method used requires a relatively large total mass of trace gas, which is not suitable for large-volume gas usage occasions.

[0008] CN111220445A proposes a dynamic gas distribution technology, which uses membrane diffusion to prepare dilution gas and is mainly used in volatile liquid applications.

[0009] CN203853061U proposes a continuous gas distribution technology, which is essentially to continuously and intermittently prepare multiple fixed-volume mixed gases for multiple independent containers by means of pressure replenishment and addition. CN102921338B belongs to the quantitative ring gas distribution method of four-way valve or six-way valve, which is suitable for normal pressure gas distribution. It is not adaptable to output higher than atmospheric pressure, continuous gas supply and online variable ratio.

[0010] Patents CN208800039U, CN205988708U, CN209155690U, etc. adopt a method of rotating a constant-volume high-pressure gas cylinder to provide a mixing method for preparing a constant-volume mixed gas, which has a large volume and low efficiency, and is more difficult to mix the proportions of trace components.

[0011] The existing technology proposed still needs to be improved in terms of continuity, variability, automation, proportion or total flexibility to adapt to the increasing technical requirements of various industries. This technology has many problems that need to be solved or improved. Summary of the invention

[0012] In view of the above shortcomings, the present invention provides a system and method for continuous and automatic preparation of trace gases. The system has the characteristics of continuous adjustable gas components and wide range of ratio changes, which is beneficial to various applications requiring quantitative preparation of multiple gas mixtures, especially the preparation of trace components. It can be used for continuous supply of gas mixtures and intermittent quantitative preparation.

[0013] The system adopted by the present invention to solve the technical problem includes a main gas control unit, a trace gas control unit, a balance gas control unit, a switching valve unit, a gas mixing unit, and a transport control unit.

[0014] The present invention also protects a method for continuous and automatic preparation of trace gases, which uses a quantitative ring to supply a quantitative trace gas to an air bag with a quantitative main component gas, and after mixing, further continuous gas mixing is performed by continuous fixed-proportion gas distribution.

[0015] Beneficial effects: The present invention discloses a system and method for configuring trace gases, and has the characteristics of continuous adjustable gas components and wide range of ratio changes, which is beneficial to various applications requiring quantitative configuration of multiple gas mixtures, especially the configuration of trace components. It can be used for continuous supply of gas mixtures and intermittent quantitative configuration.

[0016] The present invention is also beneficial in that it does not require manual hardware operation of the gas distribution during operation, is conducive to the automated preparation and supply of concentration settings, and provides a technology for continuous variation of components within a larger range, facilitating the development of more technical applications.

[0017] The present invention has strong adaptability and is conducive to the continuous connection of gas components used in experiments or production, including different types. It can reduce the inflexibility and waste of the small amount of gas required for the volumetric method in the comparative technology and the need to prepare a large amount of gas. It can also avoid the interruption caused by the change of components in the continuous method and the need to replace the damping capillary. It can be used to improve the cylinder rolling technology, thereby reducing costs and providing favorable conditions for the continuity and rapid progress of research or production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 .System main structure diagram.

[0019] Figure 2 .Basic structure diagram.

[0020] Figure 3 .Schematic diagram of six-way valve injection.

[0021] Figure 4 .Schematic diagram of gas distribution for multiple main components.

[0022] Figure 5 .Partial schematic diagram of further dilution.

[0023] Figure 6 .Partial schematic diagram of using multiple switching valves and multiple air bags.

[0024] Figure 7 . Schematic diagram of the method using two quantitative loops for a single trace gas.

[0025] Figure 8 . Schematic diagram of the method of using an extruder in a gas mixer.

[0026] As shown in the figure, 1. Main gas control unit, 1'. Second main component control, 10. Main gas cylinder, 11. Pressure reducing valve a, 12. Pressure gauge a, 13. Switch valve a, 14. Gas flow controller a, 15a. Switch valve b, 15b. Switch valve c, 2. Trace gas control unit, 20. Sample gas cylinder; 21. Pressure reducing valve b, 22. Pressure gauge b, 23a. Switch valve d, 23b. Switch valve e, 24a. Six-way valve a, 24b. Six 1. 4-way valve b, 25a. Quantitative ring a, 25b. Quantitative ring b, 26a. Vent valve a, 26b. Vent valve b, 26c. Vent port a, 3. Balance gas control unit, 30. Balance gas cylinder, 31. Pressure reducing valve c, 32. Pressure gauge c, 33. Switch valve f, 34a. Vent valve c, 34b. Vent port b, 4. Switch valve unit, 41. Four-way valve, 42a. Five-way inlet valve, 42b. Common inlet valve port, 43a. Five-way outlet valve, 43b. Valve outlet common port, 5. Delivery control unit, 51a. Switch valve g, 51b. Switch valve h, 52a Buffer tank a, 52b. Buffer tank b, 53a. Flow controller a, 53b. Flow controller b, 54a. Gas flow controller b, 54b. Exhaust port, 55a. Drain valve, 55b. Damping tube, 55c. Drain port a, 6. Gas mixer unit, 61. Mixer sealing cover, 62. Mixer cylinder, 63 a. Mixer pressure gauge, 63b. Pressure safety valve, 63c. Drain port b, 64. Liquid level gauge, 65a. Drain valve, 65b. Drain port, 66a. Heater, 66b. Agitator, 66c. Thermometer, 67a. Lower partition, 67b. Middle partition, 67c. Upper partition, 68a. Air bag one, 68b. Air bag two, 68c. Air bag three, 68d. Air bag four, 60a. Electric extruder a, 69b. Electric extruder. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments.

[0028] After the present invention determines the gas source, that is, the supply source of each component gas, the entire system can achieve unmanned operation by manually inputting control targets such as gas ratio, pressure, flow rate, and flow rate ratio change time, using general automatic control technology. Therefore, this article focuses on the principles and structures of the gas preparation process and method, and does not describe related automatic technology management solutions.

[0029] If each component has corrosion and adsorption characteristics, the selection of various walls along the gas flow needs to meet certain conditions, including valve bodies, pipelines, joints, seals, detection instruments, containers, etc., all of which are made of corrosion-resistant materials with adsorption effects less than output requirements. However, this is not a control feature of the present invention and will not be described again.

[0030] Each vent is connected to the emission system and should be treated accordingly according to the main components and trace gas properties. For example, the absorption, conversion, explosion-proof treatment of toxic or combustible substances belongs to the conventional technology in the industry and is not specifically described in the present invention.

[0031] Example 1

[0032] See also Figures 1 to 3 .

[0033] The system of this embodiment includes a main gas control unit 1, a trace gas control unit 2, a balance gas control unit 3, a switching valve unit 4, a gas mixing unit 6, and a delivery control unit 5. One side of the main gas control unit 1 is connected to the trace gas control unit 2, the other side of the main gas control unit 1 is connected to one side of the switching valve unit 4, one side of the switching valve unit 4 is connected to the delivery control unit 5, the other side of the switching valve unit 4 is connected to one side of the gas mixer unit 6, and the other side of the gas mixer unit 6 is connected to the balance gas control unit 3.

[0034] The main gas control unit 1 includes a main gas cylinder 10, a pressure reducing valve a11, a pressure gauge a12, a switch valve a13, a switch valve b15a to the switching valve unit 4, and a gas flow controller a14. The main gas cylinder 10 is connected to one side of the pressure reducing valve a11, the other side of the pressure reducing valve a11 is connected to one side of the pressure gauge a12, the other side of the pressure gauge a12 is connected to one side of the switch valve a13, the other side of the switch valve a13 is connected to one side of the gas flow controller a14, the other side of the switch valve b15a is connected to the four-way valve 41 in the switching valve unit 4, and a six-way valve a24a is provided between the gas flow controller a14 and the switch valve b15a.

[0035] The trace gas control unit 2 comprises a sample gas cylinder 20, a pressure reducing valve b21, a pressure gauge b22, a switch valve d23a, a six-way valve a24a with a quantitative loop a25a, a vent valve a26a, and a vent port a26c. The sample gas cylinder 20 is connected to the vent port a26c, and the pressure reducing valve b21, the pressure gauge b22, the switch valve d23a, and the vent valve a26a are arranged in sequence between the sample gas cylinder 20 and the vent port a26c; and a six-way valve a24a with a quantitative loop a25a is arranged between the switch valve d23a and the vent valve a26a.

[0036] The balancing gas control unit 3 includes a balancing gas cylinder 30, a pressure reducing valve c31, a pressure gauge c32, a switch valve f33, a vent valve c34a, and a vent port b34b. The balancing gas cylinder 30 is connected to the vent port b34b, and a pressure reducing valve c31, a pressure gauge c32, a switch valve f33, and a vent valve c34a are sequentially arranged between the balancing gas cylinder 30 and the vent port b34b.

[0037] The switching valve unit 4 includes a four-way valve 41, which is simultaneously connected to the switch valve b15a in the main gas control unit 1, the switch valve g51a in the delivery control unit 5, and the air bag 1 68a and the air bag 2 68b in the gas mixing unit 6.

[0038] A switch valve g51a is provided in the transport control unit 5, one side of the switch valve g51a is connected to the four-way valve 41, and the other side of the switch valve g51a is connected to the exhaust port 54b, and a buffer tank 52a, a flow controller 53a, and a gas flow controller b54a are sequentially provided between the switch valve g51a and the exhaust port 54b; the pipeline between the switch valve g51a and the four-way valve 41 is connected to one side of the drain valve 55a, and the other side of the drain valve 55a is connected to the drain port a55c, and a damping tube 55b is provided between the drain valve 55a and the drain port a55c.

[0039] The gas mixing unit 6 is provided with a mixer cylinder 62, a mixer sealing cover 61 is provided on the top of the mixer cylinder 62, the bottom of the mixer cylinder 62 is connected to the drain port 65b, and a drain valve 65a is provided between the bottom of the mixer cylinder 62 and the drain port 65b. The side of the mixer cylinder 62 is connected to the liquid level meter 64 and the thermometer 66c. An upper partition 67c and a lower partition 67a are provided in parallel in the vertical direction in the mixer cylinder 62, an air bag 1 68a and an air bag 2 68b are provided between the upper partition 67c and the lower partition 67a, and a middle partition 67b is provided between the air bag 1 68a and the air bag 2 68b. An agitator 66b and a heater 66a are provided below the lower partition 67a, and the side of the mixer cylinder 62 is also connected to the air port b63c, and a mixer pressure gauge 63a and a pressure safety valve 63b are provided in sequence between the mixer cylinder 62 and the air port b63c.

[0040] Furthermore, near the air bag, there are a plurality of electric squeezers 69a and 69b which can vibrate periodically or reciprocate and are used for squeezing the air bag, so as to accelerate the uniform mixing of the gas in the air bag.

[0041] The temperature of the gas mixer unit 6 is controlled to be slightly higher than room temperature, such as 40° C., which is conducive to accelerating the mixing of the gas in the air bag. The stirrer 66b has an intermittent stirring effect, which generates water fluctuations and provides disturbances for the air bag, and the gas in the air bag is mixed faster.

[0042] The main component gases can be the same or different. The main component is relative to the trace amount. The ratio between the main components is preferably within 1:10 or 1:50, but is not limited to this range. Any gas component can be a high-purity gas or a compound gas. The main gas is provided to the air bag through the six-way valve a24a and the switch valve b15a according to the metering control.

[0043] When the trace gas is quantified in the quantitative ring a25a, the main gas is first used to purge the quantitative ring a25a through the vent valve a26a to make the gas in the quantitative ring a25a consistent with the sample gas cylinder 20 of the trace gas. The gas is distributed to the air bag, and the air bag that has been exhausted is selected. The main gas control unit 1 uses a quantitative main component gas to blow the trace gas in the quantitative ring a25a into the air bag. Then, the mixing is carried out and the uneven gas in the pipeline is discharged to the delivery control unit 5 through the switching valve unit 4. At the same time, the inlet of the switch valve g51a is closed. After a certain period of time, the vent valve 55a is closed again, and the switch valve g51a is opened.

[0044] The quantitative ring a25a can be isobaric with the main gas source, or different pressures can be used to control the quantitative. The pressure gauge c32 detects the pressure value and converts the absolute amount of trace gas added in the quantitative ring a25a according to the temperature and pressure. The trace gas can be added multiple times during a gas bag filling process. The main component gas is supplied intermittently, and the total amount of the main component is added according to the metering method.

[0045] When the operation of the vent valve c34a of the balancing gas control unit 3 is completed or the mixer needs to be opened, the balancing gas control unit 3 closes the gas supply switch valve f33 of the balancing gas, opens the vent valve c34a for exhaust, and releases the gas pressure.

[0046] The gas mixer has a heater 66a, a thermometer 66c and a stirrer 66b, which control the temperature to be slightly higher than the room temperature, such as 40°C, which is conducive to accelerating the mixing of the gas in the air bag. The stirrer 66b has an intermittent stirring effect, which generates water fluctuations, provides disturbances for the air bag, and accelerates the mixing of the gas in the air bag.

[0047] The gas mixer is set to a maximum pressure and a minimum pressure corresponding to the pressure required by the output gas flow controller b54a. During operation, it can be changed within a certain range without precise control, such as 0.3-0.5 MPag. The pressure is adjusted by the balance gas control unit 3 to provide gas pressure to the container of the gas mixer unit 6. The volume of the air bag is 1.2 times the volume of the mixed gas single gas distribution under standard conditions according to the water volume to prevent expansion and bursting when the pressure is released after being filled with gas. The upper part of the mixer cylinder 62 has a certain space that is not filled with water. The gas balance is used to increase the pressure to the maximum inlet pressure of the output gas flow controller b54a. The pressure safety valve 63b, the mixer pressure gauge 63a and the vent valve c34a jointly control the maximum pressure not to exceed the preset value. When one of the air bags continuously outputs gas, the air pressure drops. If it is lower than the minimum pressure value, the balance gas is used to supplement it. One of the air bags outputs gas, and the other air bag prepares new gas. The two are switched using the switching valve unit 4 to maintain continuous gas supply. During the switching, the switch valve g51a at the air inlet end of the buffer tank is closed to stop the air bag from directly supplying air to the gas flow controller b54a, and the buffer tank a52a is used to temporarily supply air to the gas flow controller b54a.

[0048] The volume setting of the buffer tank a52a is related to the air bag gas distribution time, the finished gas output flow rate, and the pressure range before the output gas flow controller b54a. It is specifically set to be greater than the product of the above time and flow rate multiplied by the above pressure difference. For example, for a complete gas distribution time of the air bag, it is assumed to be 1 minute, including the switching time of each control valve, the inflation time, the air bag mixing time, the various pipeline cleaning time in the middle, and the time to increase stability. The flow output is 10NmL / min, the pressure before the flow controller is 0.3~0.5MPag, and the pressure after the output is 0.2MPag. A buffer tank a52a with an effective volume of 10mL can provide 20NmL of gas to the gas flow controller b54a when the pressure drops from 0.5MPag to 0.3MPag, that is, a buffer time of 2min. It should be adjusted according to actual conditions.

[0049] The switching valve unit 4 selectively introduces the gas source, including the gas outputted by one or more main gas control units 1 and the gas connected and outputted by one or more trace gas control units 2, into the multiple gas bags in the gas mixer unit 6. The switching valve unit 4 also selectively introduces the multiple gases prepared in the gas bags of the gas mixer unit 6 into the delivery control unit 5, and the delivery control unit 5 selects to empty through the emptying valve 55a or introduce into the selected buffer tank a52a.

[0050] During various switching operations, cleaning and replacement are required, including the six-way valve a24a, the quantitative ring a25a, the switching valve 41, the air bag and various intermediate pipelines, and the gas components of these pipelines change during operation. When the trace gas is quantified in the quantitative ring a25a, the quantitative ring a25a is first purged with the main gas through the vent valve c34a of the trace gas control unit 2, so that the gas in the quantitative ring a25a is consistent with that in the sample gas cylinder 20. The gas is distributed to the mixer air bag, and the air bag that has been exhausted is selected, and the trace gas in the quantitative ring a25a is blown into the air bag using a quantitative main component gas. Then mixing is carried out, the inlet switch valve g51a of the buffer tank a52a is closed, the uneven gas in the pipeline is discharged to the delivery control unit 5 through the switching valve 41, the drain valve 55a is opened for discharge, and the damping tube 55b plays a delay role. After a certain period of discharge, the drain valve 55a is closed again, and the inlet switch valve g51a of the buffer tank a52a is opened. The gas in the air bag continues to pass through the buffer tank a52a to provide the mixed gas to the gas flow controller b54a.

[0051] Since the daily air pressure change is generally small, less than 1% in non-stormy weather, normal pressure quantitative measurement can be used to meet the general accuracy requirement of more than 1% gas distribution relative accuracy. In actual use, one test can meet the quantitative correction requirements for one day. The test sampling port uses the emptying line emptying port of the output control unit.

[0052] Example 2

[0053] See also Figure 4 , schematic diagram of gas distribution of multiple main components.

[0054] This example is used to illustrate a method of adding trace amounts of gas to a formulation of multiple main ingredients.

[0055] Take the example of preparing precise artificial air with nitrogen and oxygen and adding a trace amount of carbon monoxide.

[0056] One of the main component gases is used, preferably an inert gas, in this case nitrogen.

[0057] Nitrogen is used in the main gas control unit 1, and oxygen is used in the second main component control unit. Similar to Example 1, a trace amount of gas is sent to the gas mixer unit 6 through the quantitative loop of the six-way valve and the switching valve unit 4 to prepare a mixed gas of a set ratio. Then, it is sent to the delivery control unit 5 through the switching valve unit 4 for output at a fixed flow rate.

[0058] The trace gas control unit 2 uses multiple parallel connections of different types of gases and switches to provide different gases to the quantitative ring a25a, thereby providing more than one trace gas supply to the gas mixer unit 6.

[0059] Example 3

[0060] See also Figure 5 , a local schematic diagram of further dilution, the meaning of which is the same as reducing the proportion of trace gas content.

[0061] One or more main component control units are used, for example, the second main component control 1' is directly placed after the delivery control unit 5, and is further mixed with the mixed gas controlled by the delivery control unit 5, and the second main component gas is mixed again with the mixed gas prepared by the gas mixer unit 6 of this system to obtain a second dilution multiple amplification of the trace gas.

[0062] The second main component gas may be the same as or different from the first main component gas.

[0063] The main application feature of this method and Example 2 is that this example is more suitable for large-flow gas distribution output, while Example 2 is relatively more suitable for small-flow gas distribution output.

[0064] For example, using a 0.100ml quantitative loop a24a, the main gas control unit 1 controls the preparation of 999.9ml hydrogen, and 0.10mmol / mol of hydrogen sulfide in hydrogen is obtained in the gas bag. After being output by the delivery control unit 5 at a speed of 1.00mL / min, it is mixed with the 999mL / min high-purity hydrogen output by the second main component control 1' to obtain a further diluted gas containing hydrogen sulfide, and its hydrogen sulfide content is 0.10μmol / mol.

[0065] If 0.100ml quantitative loop a24a is used for gas distribution 3 times, the main gas control unit 1 controls the preparation of 999.7ml hydrogen, and the gas in the quantitative loop b25b is delivered to the gas bag in batches, then 0.30mmol / mol of hydrogen sulfide in hydrogen is obtained. After being output by the delivery control unit 5 at a speed of 1.00mL / min, it is mixed with 999mL / min of high-purity hydrogen output by the second main component control 1' to obtain a further diluted gas containing hydrogen sulfide, and its hydrogen sulfide content is 0.30μmol / mol.

[0066] If a 1.00ml quantitative loop b25b is used, and the main gas control unit 1 controls the preparation of 999ml hydrogen, the gas bag forms 1.00mmol / mol, which is mixed with the 999mL / min high-purity hydrogen output by the second main component control 1' to obtain a hydrogen sulfide content of 1.00μmol / mol. Compared with not using the second main component control 1' and only using the main gas control unit 1 to directly prepare a hydrogen sulfide content of 1.00μmol / mol, the technical method of using the second main component control 1' can provide a larger final total flow rate, and after secondary mixing and gas distribution, the stability and uniformity are improved.

[0067] This method is relatively more suitable for large-flow gas supply.

[0068] Example 4

[0069] See also Figure 6 , this figure is used to explain the operation of using multiple switching valves and multiple air bags.

[0070] In the switching valve unit 4, multiple one-to-many switching valves are used, such as the five-way inlet valve 42a, which is used to switch the gas from the raw material gas to the four gas bags, such as gas bag 1 68a, gas bag 2 68b, gas bag 3 68c, and gas bag 4 68d, and the common inlet valve port 42b is used to switch the mixed gas that has been mixed from the four gas bags to the delivery control unit 5. This increases the buffer mixing time and the room for regulation of the gas distribution, and also includes the different controllable trace ratios in each gas bag, that is, the same quantitative loop is used in different gas bags, but the number of times the trace gas is added is different, and the obtained ratio of the trace gas in the gas bag is different, and then the ratio output by the delivery control unit 5 changes accordingly.

[0071] Example 5

[0072] See also Figure 7 , a schematic diagram of a method for using two quantitative loops for a single trace gas, which is used to continuously change the concentration of the transported gas over a large range, such as a small change in flow rate but a relatively large change in trace gas content, such as a concentration change range of more than 10 times in continuous operation, which is assumed to be 100 times here.

[0073] In the trace gas control unit 2, a two-way six-way valve and different quantitative rings are used. In the gas bag 1 68a, a small volume quantitative ring a25a (0.100ml) is used to prepare 999.9ml of oxygen in nitrogen in the low concentration range; in the gas bag 3 68c, a large volume quantitative ring b25b (1.00ml) is used to prepare 999ml of oxygen in nitrogen in the low concentration range. If the quantitative ring b25b is used 10 times continuously for the gas bag 3 68c, the gas bag 3 68c can form a concentration 100 times that of the gas bag 1 68a. In this way, a wide range of concentration change conditions can be easily provided to the transport control unit 5. Combined with the structure of Example 3, that is, Figure 5 , which can produce a wide range of continuous changes in trace gas content.

[0074] Alternatively, the quantitative loop may be left unchanged and a small volume quantitative loop a24a (0.100 ml) may be used to prepare the air bag more times to achieve the purpose of this example, with only the system switching control being frequent.

[0075] After being mixed evenly and exhausting the gas in the intermediate pipeline, it is sent to the delivery control unit 5. The switch valve g51a, buffer tank a52a, and flow controller a53a store and buffer low-concentration gas, and the switch valve h51b, buffer tank b52b, and flow controller b53b store and buffer high-concentration gas. This avoids the concentration lag and unevenness caused by the concentration change in the buffer tank when only one way stores and switches two gases of different concentrations.

[0076] Example 6

[0077] For the preparation of a small amount of high dilution ratio gas, such as adding a trace amount of hydrogen sulfide gas to high purity hydrogen, first go through Figure 1 , Figure 2 In the basic structure shown, a small amount of premixed gas is directly prepared at a time for preparing high-purity hydrogen, for example, 1NL of 1.00mmol / mol gas with a pressure of about 0.2-0.3MPa, and the gas is collected in a sample gas cylinder 20 as raw material gas.

[0078] The raw gas is used again in the trace gas control unit 2 to supply the gas to the quantitative ring a25a, and can be further prepared into a mixed gas with a low flow rate, for example, 1NL / min and a trace gas content of 1μmol / mol.

[0079] The above embodiments are only used to illustrate and explain the present invention, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention.

Claims

1. A system for continuous and automatic preparation of trace gases, characterized in that: The system comprises a main gas control unit (1), a trace gas control unit (2), a balance gas control unit (3), a switching valve unit (4), a gas mixer unit (6), and a delivery control unit (5); one side of the main gas control unit (1) is connected to the trace gas control unit (2), the other side of the main gas control unit (1) is connected to one side of the switching valve unit (4), one side of the switching valve unit (4) is connected to the delivery control unit (5), the other side of the switching valve unit (4) is connected to one side of the gas mixer unit (6), and the other side of the gas mixer unit (6) is connected to the balance gas control unit (3); The main gas control unit (1) comprises a main gas cylinder (10), a pressure reducing valve a (11), a pressure gauge a (12), a switch valve a (13), a switch valve b (15a) to the switch valve unit (4), and a gas flow controller a (14); the main gas cylinder (10) is connected to one side of the pressure reducing valve a (11), the other side of the pressure reducing valve a (11) is connected to one side of the pressure gauge a (12), the other side of the pressure gauge a (12) is connected to one side of the switch valve a (13), the other side of the switch valve a (13) is connected to one side of the gas flow controller a (14), the other side of the switch valve b (15a) is connected to a four-way valve (41) in the switch valve unit (4), and a six-way valve a (24a) is provided between the gas flow controller a (14) and the switch valve b (15a); The trace gas control unit (2) comprises a sample gas cylinder (20), a pressure reducing valve b (21), a pressure gauge b (22), a switch valve d (23a), a six-way valve a (24a) with a quantitative ring a (25a), a vent valve a (26a), and a vent port a (26c); wherein the sample gas cylinder (20) is connected to the vent port a (26c), and the pressure reducing valve b (21), the pressure gauge b (22), the switch valve d (23a), and the vent valve a (26a) are sequentially arranged between the sample gas cylinder (20) and the vent port a (26c); and a six-way valve a (24a) with a quantitative ring a (25a) is arranged between the switch valve d (23a) and the vent valve a (26a); The switching valve unit (4) comprises a four-way valve (41), and the four-way valve (41) is simultaneously connected to the switch valve b (15a) in the main gas control unit (1), the switch valve g (51a) in the delivery control unit (5), and the gas bag 1 (68a) and the gas bag 2 (68b) in the gas mixer unit (6); The gas mixer unit (6) is provided with a mixer cylinder (62), the top of the mixer cylinder (62) is provided with a mixer sealing cover (61), the bottom of the mixer cylinder (62) is connected to a liquid discharge port (65b), and a liquid discharge valve (65a) is provided between the bottom of the mixer cylinder (62) and the liquid discharge port (65b); the side of the mixer cylinder (62) is connected to a liquid level meter (64) and a thermometer (66c); an upper baffle (67c) and a lower baffle (67a) are provided in parallel in a vertical direction in the mixer cylinder (62), and the upper baffle (67c) and the lower baffle (67a) are provided in parallel in a vertical direction. Air bag one (68a) and air bag two (68b) are provided between the plate (67c) and the lower partition (67a), and an intermediate partition (67b) is provided between air bag one (68a) and air bag two (68b); an agitator (66b) and a heater (66a) are provided below the lower partition (67a); the side of the mixer cylinder (62) is also connected to the exhaust port b (63c); and a mixer pressure gauge (63a) and a pressure safety valve (63b) are provided in sequence between the mixer cylinder (62) and the exhaust port b (63c).

2. A system for continuous and automatic preparation of trace gases according to claim 1, characterized in that: The balancing gas control unit (3) comprises a balancing gas cylinder (30), a pressure reducing valve c (31), a pressure gauge c (32), an on-off valve f (33), a vent valve c (34a), and a vent port b (34b); the balancing gas cylinder (30) is connected to the vent port b (34b), and the pressure reducing valve c (31), the pressure gauge c (32), the on-off valve f (33), and the vent valve c (34a) are sequentially arranged between the balancing gas cylinder (30) and the vent port b (34b).

3. A system for continuous and automatic preparation of trace gases according to claim 1, characterized in that: A switch valve g (51a) is provided in the transport control unit (5), one side of the switch valve g (51a) is connected to the four-way valve (41), the other side of the switch valve g (51a) is connected to the discharge port (54b), and a buffer tank (52a), a flow controller (53a), and a gas flow controller b (54a) are provided in sequence between the switch valve g (51a) and the discharge port (54b); a pipeline between the switch valve g (51a) and the four-way valve (41) is connected to one side of the drain valve (55a), the other side of the drain valve (55a) is connected to the drain port a (55c), and a damping tube (55b) is provided between the drain valve (55a) and the drain port a (55c).

4. A system for continuous and automatic preparation of trace gases according to claim 1, characterized in that: There are a plurality of first electric squeezers (69a) and second electric squeezers (69b) near the air bag, which can vibrate periodically or reciprocate, and are used for squeezing the air bag, so as to accelerate the uniform mixing of the gas in the air bag.

5. A system for continuous and automatic preparation of trace gases according to claim 1, characterized in that: The temperature of the gas mixer unit (6) is higher than room temperature.

6. A method for continuous automatic preparation of gas using the system of claim 1, characterized in that: The method uses a quantitative ring to supply a quantitative trace gas to an air bag with a quantitative main component gas, and after mixing, further continuous gas mixing is performed through a continuous fixed-proportion gas distribution method.

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