Humidification and distribution control system and method for normal-temperature standard gas

Abstract

The invention discloses a humidification and distribution control system and method for normal-temperature standard gas. The system comprises a zero gas humidification pipeline, a second zero gas pipeline, a standard gas pipeline, a gas mixing chamber, a calibration gas pipeline and a control unit. The zero gas humidification pipeline comprises two first zero gas pipelines and a permeation humidification unit, the input ends of the first zero gas pipeline and the second zero gas pipeline are both used for inputting zero gas, the two first zero gas pipelines are connected with the permeation humidification unit, the permeation humidification unit comprises a Nafion humidifier and a moisture generation assembly, and a humidity sensor is arranged on the dry side of the Nafion humidifier; mass flow controllers are arranged on the first zero gas pipeline, the second zero gas pipeline and the standard gas pipeline; the gas mixing chamber is connected with the permeation humidification unit, the second zero gas pipeline and the standard gas pipeline so as to mix standard gas and zero gas, and the gas mixing chamber is connected with the calibration gas pipeline; the control unit is connected with the humidity sensor and each mass flow controller, and the two first zero gas pipelines do not work at the same time. According to the technical scheme provided by the invention, calibration requirements of different humidity can be met.

Description

Technical Field

[0001] This invention relates to the field of standard gas humidification control technology, and in particular to a humidification and gas distribution control system and method for standard gases at room temperature. Background Technology

[0002] In the calibration of gas analyzers, the standard gas used for metrological calibration is usually a dry standard gas, while the sample gas has a certain humidity, and the humidity of the sample gas directly affects the response sensitivity and measurement accuracy of the gas analyzer. Therefore, using a standard gas with ambient humidity to calibrate the gas analyzer is more in line with the operating conditions of the gas analyzer.

[0003] Among related technologies, the humidification and gas mixing technology for standard gases at room temperature is difficult to simultaneously cover the calibration requirements of high humidity (volume ratio > 1%) and ultra-low humidity (close to dry gas) in terms of humidity control. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this invention provides a humidification and gas distribution control system and method for ambient temperature standard gas, which can generate calibration gases with different humidity levels, covering calibration needs for both high and ultra-low humidity.

[0005] The first aspect of the present invention provides a humidification and gas distribution control system for a standard gas at room temperature, comprising a zero gas humidification pipeline, a second zero gas pipeline, a standard gas pipeline, a mixing chamber, a calibration gas pipeline, and a control unit; The zero-air humidification pipeline includes two first zero-air pipelines and one permeation humidification unit. The input ends of the first zero-air pipelines and the second zero-air pipelines are used to input zero air. The output ends of the two first zero-air pipelines are connected to the wet side input end of the permeation humidification unit. The permeation humidification unit includes a Nafion humidifier and a moisture generation component. The dry side of the Nafion humidifier is equipped with a humidity sensor. The moisture generation component is used to provide moisture with different humidity levels. The input end of the standard gas pipeline is used to input standard gas. The first zero gas pipeline, the second zero gas pipeline and the standard gas pipeline are all equipped with mass flow controllers with corresponding ranges. The ranges of the mass flow controllers on the two first zero gas pipelines are different. The input end of the mixing chamber is connected to the wet-side output end of the permeation humidification unit, the output end of the second zero gas pipeline, and the output end of the standard gas pipeline. The mixing chamber is used to mix the standard gas and the zero gas. The output end of the mixing chamber is connected to the input end of the calibration gas pipeline. The output end of the calibration gas pipeline is used to supply gas to the gas analyzer. The control unit is connected to the humidity sensor, the moisture generating component, and each of the mass flow controllers. It is used to adjust the flow rate of the mass flow controllers on the first zero gas pipeline and the second zero gas pipeline according to the information collected by the humidity sensor, and to adjust the moisture generated by the moisture generating component to adjust the humidity of the calibration gas. The two first zero gas pipelines do not work at the same time.

[0006] In one optional embodiment, the moisture generating component includes an air pump and a gas washing bottle. The air pump is connected to the control unit, which is also used to control whether the air pump accesses ambient air through the gas washing bottle to provide two different humidity levels to the Nafion humidifier.

[0007] In an optional embodiment, the mass flow controllers on the two first zero-gas lines and the second zero-gas line are sequentially designated as a first mass flow controller, a second mass flow controller, and a third mass flow controller, with the range of the second mass flow controller being greater than that of the first mass flow controller; the control unit is further configured to: If the calibration gas is an ultra-low humidity gas, control the air pump to connect to the ambient air, and control the first mass flow controller to adjust the zero gas flowing through the first mass flow controller. The humidity sensor collects a first humidity, wherein the first humidity is greater than a first preset humidity, and the first preset humidity is calculated based on the first target humidity of the calibration gas. The control parameters of the third mass flow controller are determined based on the first humidity calculation. The third mass flow controller is controlled according to its control parameters to regulate the zero gas flowing through it.

[0008] In an alternative embodiment, the control unit is further configured to: If the calibration gas is a high-humidity gas, the vacuum pump and the second mass flow controller are controlled. The second humidity collected by the humidity sensor is obtained, wherein the second humidity is greater than a second preset humidity, and the second preset humidity is calculated based on the second target humidity of the calibration gas; The control parameters of the third mass flow controller are determined based on the second humidity calculation. The third mass flow controller is controlled according to its control parameters to regulate the zero gas flowing through it.

[0009] In an optional embodiment, in the control unit, if the calibration gas is a high-humidity gas, the control of the vacuum pump and the second mass flow controller includes: Determine whether the target humidity of the calibration gas is above the ambient humidity; If so, control the air pump to connect to ambient air through the gas washing bottle; otherwise, control the air pump to connect to ambient air. The second mass flow controller is controlled to regulate the zero gas flowing through it.

[0010] In an optional embodiment, the mass flow controller on the standard gas pipeline is a fourth mass flow controller, and the control unit is further configured to: The control parameters of the fourth mass flow controller are determined based on the control parameters of the third mass flow controller. The fourth mass flow controller is controlled according to its control parameters to regulate the standard gas flowing through it.

[0011] In an optional embodiment, a sample gas pipeline and a calibration switching valve are also included; The input end of the sample gas pipeline is used to input sample gas; The calibration switching valve includes a first input terminal, a second input terminal, and a common output terminal. The first input terminal is connected to the output terminal of the calibration gas pipeline, the second input terminal is connected to the output terminal of the sample gas pipeline, and the common output terminal is used to connect to a gas analyzer. Furthermore, the calibration switching valve also includes a control terminal, and the control unit is connected to the control terminal of the calibration switching valve for controlling whether the first input terminal or the second input terminal is connected to the common output terminal.

[0012] In one optional embodiment, the humidity sensor is located at the dry-side outlet of the Nafion humidifier; the wet-side inlet and wet-side outlet of the Nafion humidifier are provided with differential pressure holes, and each differential pressure hole is equipped with a humidity detection element for monitoring the humidity of the air, and the humidity detection element is electrically connected to the control unit.

[0013] In one optional embodiment, the standard gas pipeline includes at least two standard gas sub-pipelines, each of which is equipped with a switching valve connected to the control unit. One end of each switching valve is connected to the fourth mass flow control valve, and the other end is used to input different types of standard gases.

[0014] A second aspect of the present invention provides a method for controlling the humidification and gas distribution of a standard gas at room temperature, applied to the humidification and gas distribution control system for a standard gas at room temperature as described in the first aspect of the present invention, the method comprising: Adjust the zero gas flow rate of the mass flow controllers on the first zero gas pipeline and the second zero gas pipeline according to the information collected by the humidity sensor, and adjust the humidity generated by the humidity generating component to adjust the humidity of the calibration gas.

[0015] The technical solution provided by this invention may include the following beneficial effects: Two mass flow controllers with different ranges are used in the first zero gas pipelines to control the flow rate input to the permeation humidification unit. The humidity sensor in the permeation humidification unit provides feedback on the humidification status of the zero gas. The control unit adjusts the flow rate of each mass flow controller based on the feedback from the humidity sensor and combines it with the humidity provided by the moisture generation component to achieve closed-loop humidity control. Furthermore, by selecting one of the two mass flow controllers in the first zero gas pipeline and combining it with the mass flow controllers in the second zero gas pipeline and the standard gas pipeline, high humidity or ultra-low humidity standard gas configuration can be achieved to obtain the calibration gas with the required humidity, thereby meeting the diverse humidity requirements of the gas analyzer for calibrating the standard gas. Attached Figure Description

[0016] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts in the exemplary embodiments of the invention.

[0017] Figure 1 This is a structural block diagram of a room temperature standard gas humidification and gas distribution control system shown in an embodiment of the present invention; Figure 2 This is a first schematic diagram of a humidification and gas distribution control system for standard gas at room temperature, as shown in an embodiment of the present invention. Figure 3 This is a second schematic diagram of a humidification and gas distribution control system for standard gas at room temperature, as shown in an embodiment of the present invention. Figure 4 This is another structural block diagram of the humidification and gas distribution control system for standard gas at room temperature shown in the embodiments of the present invention; Figure 5 This is a third schematic diagram of a humidification and gas distribution control system for standard gas at room temperature, as shown in an embodiment of the present invention. Figure 6 This is a control schematic diagram of a humidification and gas distribution control system for standard gas at room temperature, as shown in an embodiment of the present invention. In the diagram: 1. Zero gas source; 11. N2 bottle; 2. Standard gas source; 20. Switch valve; 21. SO2 bottle; 22. NO bottle; 23. NO2 bottle; 24. First switch valve; 25. Second switch valve; 26. Third switch valve; 31. First mass flow controller; 32. Second mass flow controller; 33. Third mass flow controller; 34. Fourth mass flow controller; 4. Permeation humidification unit; 41. Nafion humidifier; 411. Humidity sensor; 412. Inner tube; 413. Outer tube; 42. Moisture generation assembly; 421. Particulate filter; 422. Gas washing bottle; 423. Filter; 424. Vacuum pump; 425. Moisture detection element; 5. Mixing chamber; 6. Gas analyzer; 7. Calibration switching valve; 8. Sample gas source; 9. Control unit. Detailed Implementation

[0018] Embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be more thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0020] It should be understood that although the terms "first," "second," "third," etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] The technical solutions of the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0022] See Figures 1-6This invention provides a humidification and gas distribution control system for a standard gas at room temperature, including a zero-gas humidification pipeline, a second zero-gas pipeline, a standard gas pipeline, a mixing chamber 5, a calibration gas pipeline, and a control unit 9. The zero-gas humidification pipeline includes two first zero-gas pipelines and a permeation humidification unit 4. The input ends of both the first and second zero-gas pipelines are used to input zero gas, and the output ends of both first zero-gas pipelines are connected to the wet-side input end of the permeation humidification unit 4. The permeation humidification unit 4 is used to humidify the zero gas flowing through it. The permeation humidification unit includes a Nafion humidifier 41 and a moisture generation component 42. A humidity sensor 411 is provided on the dry side of the Nafion humidifier 41 to detect the humidity of the zero gas after humidification in the Nafion humidifier 41. The moisture generation component 42 is used to provide moisture with different humidity levels. The input end of the standard gas pipeline is used to input standard gas. The gas analyzer 6 is equipped with a mass flow controller with a corresponding range on the first zero gas pipeline, the second zero gas pipeline, and the standard gas pipeline. The mass flow controllers on the two first zero gas pipelines have different ranges. The input end of the mixing chamber 5 is connected to the wet-side output end of the permeation humidification unit 4, the output end of the second zero gas pipeline, and the output end of the standard gas pipeline. The mixing chamber 5 is used to mix the standard gas and the zero gas. The output end of the mixing chamber 5 is connected to the input end of the calibration gas pipeline. The output end of the calibration gas pipeline is used to supply gas to the gas analyzer 6. The control unit 9 is connected to the humidity sensor 411, the moisture generation component 42, and each mass flow controller. It is used to adjust the flow rate of the mass flow controllers on the first zero gas pipeline and the second zero gas pipeline according to the information collected by the humidity sensor 411, and to adjust the moisture generated by the moisture generation component 42 to adjust the humidity of the calibration gas. The two first zero gas pipelines do not work at the same time.

[0023] In this embodiment, the input ends of the second zero gas pipeline and the two first zero gas pipelines are all connected to the zero gas source 1. The zero gas source 1 is used to provide zero gas, which can be N2, etc. The input end of the standard gas pipeline is connected to the standard gas source 2. The standard gas source 2 is used to provide standard gas, which can be SO2, NO, or NO2, etc. The mass flow controllers on the two first zero gas pipelines, the second zero gas pipeline, and the standard gas pipeline can be the first mass flow controller 31, the second mass flow controller 32, the third mass flow controller 33, and the fourth mass flow controller 34, respectively. The input ends and output ends of the two first zero gas pipelines are connected in parallel, which can be regarded as the first mass flow controller 31 and the second mass flow controller 32 connected in parallel. At the same time, the ranges of the first mass flow controller 31 and the second mass flow controller 32 are different, with the range of the second mass flow controller 32 being greater than that of the first mass flow controller 31, and they do not work at the same time. The permeation humidification unit 4 is used to humidify the zero gas flowing through the permeation humidification unit 4, and the mixing chamber 5 is used to mix the zero gas and the standard gas to form a calibration gas, wherein the standard gas is then transferred to the mixing chamber 5 after all the zero gas has been transferred to the mixing chamber 5.

[0024] like Figure 2 As shown, in this embodiment, the MFC (Mass Flow Controller) is a control element for precisely controlling the flow rate of gases such as zero gas and standard gas. Besides being suitable for flow control of high-humidity gases, it is also suitable for configuring ultra-low-humidity gases. Zero gas source 1 supplies zero gas, which can be N2, stored in a steel cylinder. The volume concentration of water vapor in the cylinder can be 3 ppm, i.e., dry-basis zero gas. Standard gases can be SO2, NO, NO2, etc. Taking zero gas source 1 as a single N2 cylinder 11 and standard gas source 2 as a single NO cylinder 22 as an example, the first mass flow controller 31, the second mass flow controller 32, the third mass flow controller 33, and the fourth mass flow controller 34, i.e., MFC1, MFC2, MFC3, and MFC4, are connected to the outlet of N2 cylinder 11. The outlets of MFC1 and MFC2 are connected to the mixed gas via the permeation humidification unit 4. The outlet side of MFC3 is connected to the mixing chamber 5. MFC1, MFC2, and MFC3 are used to control the flow distribution of N2. The inlet side of MFC4 is connected to the outlet of NO bottle 22. The outlet side of MFC4 is connected to the mixing chamber 5. MFC4 is used to control the flow of NO. The permeation humidification unit 4 humidifies the N2 flowing through the permeation humidification unit 4 to the set humidity. The mixing chamber 5 fully mixes N2 and NO to generate calibration gas. This calibration gas can be transmitted to the gas analyzer 6 for calibration of the standard gas NO.

[0025] Among them, the zero gas source 1 includes N2 cylinder 11. It should be noted that the air intake side of MFC1, MFC2, and MFC3 are all connected to the zero gas source 1. The zero gas source 1 can be the same N2 cylinder, or different N2 cylinders of the same specification, and the same applies to the same type of standard gas.

[0026] In some embodiments, the first mass flow controller 31 and the fourth mass flow controller 34 have a range of 100 ml, and the second mass flow controller 32 and the third mass flow controller 33 have a range of 5 L. Specifically, MFC1 and MFC4 have a range of 100 ml, MFC2 and MFC3 have a range of 5 L, MFC1, MFC2 and MFC3 are all connected to bottle N2 11, and MFC4 is connected to bottle NO 22. MFC2 and MFC3 can be activated. MFC2 regulates the flow rate of N2 supplied to the permeation humidification unit 4, where N2 is humidified. Based on feedback from the humidity sensor 411, MFC3 regulates the flow rate of N2 supplied to the mixing chamber 5 to dry the humidified N2 and reduce its humidity to the corresponding target humidity. In addition, in conjunction with the regulation of the moisture generation component, MFC2, and MFC3, MFC4 is controlled to regulate the flow rate of NO supplied to the mixing chamber 5. The mixing chamber 5 thoroughly mixes NO and N2 to obtain a high-humidity calibration gas with the target humidity and target concentration. This calibration gas is then supplied to the gas analyzer 6 for calibration analysis.

[0027] like Figure 3 As shown, in an optional embodiment, it further includes a sample gas pipeline and a calibration switching valve 7; the input end of the sample gas pipeline is used to input sample gas; the calibration switching valve 7 includes a first input end, a second input end, and a common output end, the first input end is connected to the output end of the calibration gas pipeline, the second input end is connected to the output end of the sample gas pipeline, and the common output end is used to connect to the gas analyzer 6; and the calibration switching valve 7 further includes a control end, the control unit 9 is connected to the control end of the calibration switching valve 7, and is used to control whether the first input end or the second input end is connected to the common output end. The calibration switching valve 7 is a three-way switching valve. To improve the detection efficiency of the gas analyzer 6, a three-way switching valve can be installed on the connecting pipeline between the mixing chamber 5 and the gas analyzer 6. The first input end of the three-way switching valve is connected to the output end of the mixing chamber 5 through the calibration gas pipeline, the second input end is connected to the sample gas source 8 through the sample gas pipeline, and the common output end is connected to the gas analyzer 6. The control unit 9 controls the three-way switching valve to switch between the calibration gas output from the mixing chamber 5 and the sample gas output from the sample gas source 8, so as to switch between calibration mode and test analysis mode.

[0028] In some embodiments, the permeation humidification unit 4 includes a Nafion humidifier 41 and a moisture generating assembly 42; the dry-side input of the Nafion humidifier 41 is connected to the output of two first zero-air pipelines, and the dry-side output is connected to the input of the mixing chamber 5; a humidity sensor 411 is located at the dry-side outlet of the Nafion humidifier 41; and differential pressure holes are evenly distributed at the wet-side inlet and wet-side outlet of the Nafion humidifier 41, with a moisture detection element 425 for monitoring the humidity of the moisture at each differential pressure hole, and the moisture detection element 425 is electrically connected to the control unit 9, such as... Figure 6 As shown. The humidity detection element 425 can acquire the humidity of the moisture generated by the humidity generating component 42. The control unit 9 acquires the humidity of the moisture and can use it as the basis for controlling the mass flow control valve.

[0029] The Nafion humidifier 41 includes an inner tube 412 and an outer tube 413. The inner tube 412 passes through the outer tube 413. The left end of the inner tube 412 is connected to the air outlet side of MFC1 / MFC2, which is the dry-side inlet. The right end is connected to the air inlet side of the mixing chamber 5, which is the dry-side outlet. The dry-side outlet is connected to the mixing chamber 5, thus forming an airflow channel for zero air in the inner tube 412. A humidity sensor 411 is installed at the dry-side outlet to monitor the humidity of the zero air after humidification. The outer tube 413 has a wet-side inlet and a wet-side outlet, and a differential pressure orifice is arranged in pairs at the wet-side inlet and outlet for detecting flow rate and humidity. In one example, a humidity detection element 425 is installed at the differential pressure orifice to monitor humidity flow rate and humidity. It should be noted that the differential pressure orifice is equipped with a moisture detection element 425 to monitor moisture flow rate, and other related technologies are known to those skilled in the art, and will not be described in detail here. Furthermore, an airflow channel for moisture is formed between the outer tube 413 and the inner tube 412, and the inner tube 412 uses a Nafion membrane. The Nafion membrane has selective permeation characteristics, which can transfer water molecules from the wet side with higher humidity to the dry side with lower humidity, thereby achieving humidification of the zero air through moisture permeation.

[0030] like Figure 2 , Figure 4 and Figure 5As shown, preferably, the moisture generating component 42 includes a vacuum pump 424 and a gas washing bottle 422. The vacuum pump 424 is connected to the control unit 9, which also controls whether the vacuum pump 424 accesses ambient air through the gas washing bottle 422 to provide two different humidity levels to the Nafion humidifier 41. The gas washing bottle 422 is used for humidification; the water in the gas washing bottle 422 can be deionized pure water. The vacuum pump 424 can directly draw in ambient air, in which case the humidity is the same as the ambient humidity, generally a high-humidity gas. Alternatively, the vacuum pump 424 can draw in ambient air through the gas washing bottle 422, where the humidity can reach 100%. Therefore, the two different humidity levels are generally close to 100% humidity or ambient humidity.

[0031] In some embodiments, the control unit 9 is used for: If the calibration gas is an ultra-low humidity gas, control the air pump to connect to the ambient air, and control the first mass flow controller to adjust the zero gas flowing through the first mass flow controller. The humidity sensor collects a first humidity, wherein the first humidity is greater than a first preset humidity, and the first preset humidity is calculated based on the first target humidity of the calibration gas. The control parameters of the third mass flow controller are determined based on the first humidity calculation. The third mass flow controller is controlled according to its control parameters to regulate the zero gas flowing through it.

[0032] In some embodiments, the control unit is further configured to: If the calibration gas is a high-humidity gas, the vacuum pump and the second mass flow controller are controlled. The second humidity collected by the humidity sensor is obtained, wherein the second humidity is greater than a second preset humidity, and the second preset humidity is calculated based on the second target humidity of the calibration gas; The control parameters of the third mass flow controller are determined based on the second humidity calculation. The third mass flow controller is controlled according to its control parameters to regulate the zero gas flowing through it.

[0033] Further, in the control unit, if the calibration gas is a high-humidity gas, the control of the vacuum pump and the second mass flow controller includes: Determine whether the target humidity of the calibration gas is above the ambient humidity; If so, control the air pump to connect to ambient air through the gas washing bottle; otherwise, control the air pump to connect to ambient air. The second mass flow controller is controlled to regulate the zero gas flowing through it.

[0034] Furthermore, the control unit is also used for: The control parameters of the fourth mass flow controller are determined based on the control parameters of the third mass flow controller. The fourth mass flow controller is controlled according to its control parameters to regulate the standard gas flowing through it.

[0035] In this embodiment, after determining the zero humidity in the Nafion humidifier, the flow rates of MFC3 and MFC4 are calculated based on the speed of the air pump and the flow rate of MFC1. MFC4 can be calculated after the control parameters of MFC3 are determined. Finally, MFC3 and MFC4 are controlled synchronously.

[0036] If the target humidity of the calibration gas is above the ambient humidity, the vacuum pump 424 can be connected to the ambient air through the gas washing bottle 422; otherwise, the vacuum pump 424 is connected to the ambient air. The gas washing bottle 422 has a particulate filter 421 at its input end, and the vacuum pump 424 has a filter 423 at its input end. When the vacuum pump 424 is connected to the gas washing bottle 422 through the filter 423, it can provide 100% humidity to the Nafion humidifier 41. When the vacuum pump 424 is not connected to the gas washing bottle 422, it can provide the Nafion humidifier 41 with humidity of the same concentration as the ambient air.

[0037] When the calibration gas is a high-humidity gas, the ambient air, driven by the vacuum pump 424, passes sequentially through the particulate filter 421, the gas washing bottle 422, and the filter 423 to remove particulate impurities and water-soluble impurities. Then, the vacuum pump 424 pushes the air to the wet side of the Nafion humidifier 41 under positive pressure, providing the Nafion humidifier 41 with humidity close to 100%. The flow rate and humidity are detected at the differential pressure port of the outer tube 413 of the Nafion humidifier 41. If the humidity sensor 411 detects that the humidity is higher than the target humidity, the zero gas flowing through the MFC3 can be turned on to dry the excessively humid zero gas in the mixing chamber to reduce the humidity, thereby obtaining the required calibration gas. If the humidity sensor 411 detects that the humidity is lower than the target humidity, the vacuum pump 424 can directly introduce lower humidity gas from the environment to generate the required humidity zero gas.

[0038] When the calibration gas is an ultra-low humidity gas, it is not necessary to supply 100% humidity to the Nafion humidifier 41. In this case, the air pump 424 directly connects to the ambient air through the filter 423, thus supplying ambient air to the Nafion humidifier 41. This ambient air also has a certain humidity, and the humidity is higher than that of the ultra-low humidity calibration gas. Since the ultra-low humidity calibration gas is generally below the detectable humidity of the humidity sensor, the humidified zero gas can be further dried. This zero gas enters the Nafion humidifier 41 through MFC1. Therefore, after turning on MFC1, MFC3 needs to be turned on to further dry the humidified zero gas until the required humidity is obtained. The required amount of calibration gas is then introduced to obtain the required humidity and concentration of the calibration gas. Among them, the humidity sensor 411 is for ultra-low humidity concentration gases. Due to its limited detection accuracy, its detection results are inaccurate. In this embodiment, it is not necessary to accurately monitor ultra-low humidity. The target humidity can be configured by calculating and controlling MFC3 and MFC4 based on the feedback from the humidity sensor 411.

[0039] When the vacuum pump 424, in conjunction with the gas washing bottle 422, provides moisture, the moisture generating assembly 42 includes a particulate filter 421, a gas washing bottle 422, and a vacuum pump 424 connected in sequence. The other end of the particulate filter 421 is connected to ambient air, and the other end of the vacuum pump 424 is connected to the wet-side inlet of the Nafion humidifier 41. Driven by the vacuum pump 424, the ambient air passes sequentially through the particulate filter 421, the gas washing bottle 422, and the filter 423 to remove particulate impurities and water-soluble impurities. The air is then positively pushed to the wet side of the Nafion humidifier 41 by the vacuum pump 424, and the flow rate and humidity are detected at the differential pressure port of the outer tube 413 of the Nafion humidifier 41. The moisture generating assembly 42 pre-treats the ambient air to obtain clean moisture, preventing impurities from entering the Nafion humidifier 41 and causing interference. Furthermore, the Nafion humidifier 41 separates dry and wet air, resulting in significantly improved humidification efficiency.

[0040] Common methods of humidifying zero gas, such as bubbling or direct water spraying, can easily introduce liquid water or impurities into the standard gas, thus contaminating the gas path. In this embodiment, humidifying the zero gas with moisture can avoid the introduction of liquid water, and the moisture generating component 42 removes impurities from the ambient air, which can also prevent the introduction of impurities into the standard gas.

[0041] For the generation of ultra-low humidity calibration gas, MFC1 and MFC3 are turned on. First, the flow rate of N2 delivered to the permeation humidification unit 4 is adjusted by MFC1. Based on the humidity information fed back by the humidity sensor 411, the flow rate of N2 delivered to the mixing chamber 5 by MFC3 is adjusted to dry the humidified N2. The flow rate of NO delivered to the mixing chamber 5 by MFC4 is adjusted. The mixing chamber 5 fully mixes NO and N2 to obtain ultra-low humidity calibration gas with target humidity and target concentration. This calibration gas is delivered to the gas analyzer 6 for calibration analysis.

[0042] like Figures 4-6 As shown, in an optional embodiment, the standard gas pipeline includes at least two standard gas sub-pipelines, each of which is provided with a switching valve 20 connected to the control unit 9. One end of each switching valve 20 is connected to the fourth mass flow control valve 34, and the other end is used to input different types of standard gases.

[0043] The standard gas source 2 provides at least two different standard gases, using different standard gas cylinders as carriers. Therefore, the standard gas cylinders can be SO2 cylinder 21, NO cylinder 22, or NO2 cylinder 23. The switching valves 20 include a first switching valve 24, a second switching valve 25, and a third switching valve 26. The standard gases are SO2, NO, and NO2. The inlet side of the first switching valve 24 is connected to the outlet side of SO2 cylinder 21, and the outlet side is connected to the inlet side of MFC4. The inlet side of the second switching valve 25 is connected to the outlet side of NO cylinder 22, and the outlet side is connected to the inlet side of MFC4. The inlet side of the third switching valve 26 is connected to the outlet side of NO2 cylinder 23, and the outlet side is connected to the inlet side of MFC4. According to the testing requirements of the gas analyzer 6, the control unit 9 controls the opening of one corresponding switching valve 20 and the closing of the other switching valves 20, cooperating with MFC1, MFC2, and MFC3 to achieve the configuration of standard gases with different humidity concentrations. As can be seen, the combination of multiple switching valves 20 and multiple MFCs allows for the rapid configuration of standard gases with multiple components and different concentrations, improving gas mixing flexibility, and the structure is simple and reliable. Standard gas cylinders include, but are not limited to, SO2 cylinder 21, NO cylinder 22 and NO2 cylinder 23, and can also be other gas cylinders identical to the sample gas.

[0044] It should be noted that only one type of standard gas is used in each calibration. For two adjacent calibration operations, zero gas can be introduced after the previous calibration to remove any residual standard gas in the pipeline, so that it can be used for the next calibration operation.

[0045] This invention also provides a method for controlling the humidification and gas distribution of a standard gas at room temperature, applied to the aforementioned control system for humidification and gas distribution of a standard gas at room temperature. The method includes: adjusting the zero gas flow rate of the mass flow controllers on the first zero gas pipeline and the second zero gas pipeline based on information collected by a humidity sensor, and adjusting the humidity generated by the humidification generator to adjust the humidity of the calibration gas.

[0046] The method embodiments have been described in detail in the above system embodiments, and therefore will not be repeated here.

[0047] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A humidification and gas distribution control system for standard gas at room temperature, characterized in that, It includes a zero-gas humidification pipeline, a second zero-gas pipeline, a standard gas pipeline, a mixing chamber, a calibration gas pipeline, and a control unit; The zero-air humidification pipeline includes two first zero-air pipelines and one permeation humidification unit. The input ends of the first zero-air pipelines and the second zero-air pipelines are used to input zero air. The output ends of the two first zero-air pipelines are connected to the wet side input end of the permeation humidification unit. The permeation humidification unit includes a Nafion humidifier and a moisture generation component. The dry side of the Nafion humidifier is equipped with a humidity sensor. The moisture generation component is used to provide moisture with different humidity levels. The input end of the standard gas pipeline is used to input standard gas. The first zero gas pipeline, the second zero gas pipeline and the standard gas pipeline are all equipped with mass flow controllers with corresponding ranges. The ranges of the mass flow controllers on the two first zero gas pipelines are different. The input end of the mixing chamber is connected to the wet-side output end of the permeation humidification unit, the output end of the second zero gas pipeline, and the output end of the standard gas pipeline. The mixing chamber is used to mix the standard gas and the zero gas. The output end of the mixing chamber is connected to the input end of the calibration gas pipeline. The output end of the calibration gas pipeline is used to supply gas to the gas analyzer. The control unit is connected to the humidity sensor, the moisture generating component, and each of the mass flow controllers. It is used to adjust the flow rate of the mass flow controllers on the first zero gas pipeline and the second zero gas pipeline according to the information collected by the humidity sensor, and to adjust the moisture generated by the moisture generating component to adjust the humidity of the calibration gas. The two first zero gas pipelines do not work at the same time.

2. The humidification and gas distribution control system for standard gas at room temperature according to claim 1, characterized in that, The moisture generating component includes an air pump and a gas washing bottle. The air pump is connected to the control unit, which is also used to control whether the air pump connects to ambient air through the gas washing bottle to provide two different humidity levels to the Nafion humidifier.

3. The humidification and gas distribution control system for standard gas at room temperature according to claim 2, characterized in that, The mass flow controllers on the two first zero-gas lines and the second zero-gas line are, in sequence, a first mass flow controller, a second mass flow controller, and a third mass flow controller, with the second mass flow controller having a larger range than the first mass flow controller; the control unit is further configured to: If the calibration gas is an ultra-low humidity gas, control the air pump to connect to the ambient air, and control the first mass flow controller to adjust the zero gas flowing through the first mass flow controller. The humidity sensor collects a first humidity, wherein the first humidity is greater than a first preset humidity, and the first preset humidity is calculated based on the first target humidity of the calibration gas. The control parameters of the third mass flow controller are determined based on the first humidity calculation. The third mass flow controller is controlled according to its control parameters to regulate the zero gas flowing through it.

4. The humidification and gas distribution control system for ambient temperature standard gas according to claim 3, characterized in that, The control unit is also used for: If the calibration gas is a high-humidity gas, the vacuum pump and the second mass flow controller are controlled. The second humidity collected by the humidity sensor is obtained, wherein the second humidity is greater than a second preset humidity, and the second preset humidity is calculated based on the second target humidity of the calibration gas; The control parameters of the third mass flow controller are determined based on the second humidity calculation. The third mass flow controller is controlled according to its control parameters to regulate the zero gas flowing through it.

5. The humidification and gas distribution control system for standard gas at room temperature according to claim 4, characterized in that, In the control unit, if the calibration gas is a high-humidity gas, the control of the vacuum pump and the second mass flow controller includes: Determine whether the target humidity of the calibration gas is above the ambient humidity; If so, control the air pump to connect to ambient air through the gas washing bottle; otherwise, control the air pump to connect to ambient air. The second mass flow controller is controlled to regulate the zero gas flowing through it.

6. The humidification and gas distribution control system for ambient temperature standard gas according to claim 3 or 4, characterized in that, The mass flow controller on the standard gas pipeline is a fourth mass flow controller, and the control unit is also used for: The control parameters of the fourth mass flow controller are determined based on the control parameters of the third mass flow controller. The fourth mass flow controller is controlled according to its control parameters to regulate the standard gas flowing through it.

7. The humidification and gas distribution control system for ambient temperature standard gas according to claim 1, characterized in that, It also includes sample gas pipelines and calibration switching valves; The input end of the sample gas pipeline is used to input sample gas; The calibration switching valve includes a first input terminal, a second input terminal, and a common output terminal. The first input terminal is connected to the output terminal of the calibration gas pipeline, the second input terminal is connected to the output terminal of the sample gas pipeline, and the common output terminal is used to connect to a gas analyzer. Furthermore, the calibration switching valve also includes a control terminal, and the control unit is connected to the control terminal of the calibration switching valve for controlling whether the first input terminal or the second input terminal is connected to the common output terminal.

8. The humidification and gas distribution control system for standard gas at room temperature according to claim 1, characterized in that, The humidity sensor is located at the dry side outlet of the Nafion humidifier; the wet side inlet and wet side outlet of the Nafion humidifier are provided with differential pressure holes, and each differential pressure hole is equipped with a humidity detection element for monitoring the humidity of the air, and the humidity detection element is electrically connected to the control unit.

9. The humidification and gas distribution control system for ambient temperature standard gas according to claim 6, characterized in that, The standard gas pipeline includes at least two standard gas sub-pipelines. Each standard gas sub-pipeline is equipped with a switching valve connected to the control unit. One end of each switching valve is connected to the fourth mass flow control valve, and the other end is used to input different types of standard gases.

10. A method for controlling the humidification and gas distribution of a standard gas at room temperature, characterized in that, The method, applied to the humidification and gas distribution control system for ambient temperature standard gas as described in any one of claims 1 to 9, comprises: Based on the information collected by the humidity sensor, the zero gas flow rate of the mass flow controllers on the first and second zero gas pipelines is adjusted, and the humidity generated by the humidity generating component is adjusted to adjust the humidity of the calibration gas.

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