High-pressure low-humidity gas dew point calibration device and method

Abstract

The invention discloses a high-pressure low-humidity gas dew point calibration device and method. The device comprises a dry gas source, a first stagnation valve, a second stagnation valve, a first pressure reducing valve, a second pressure reducing valve, constant-temperature water bath circulating equipment, a back pressure type pressure regulating valve, a precise dew point instrument and a pipeline. The dry gas source is used for providing dry gas to purge the pipeline; calibrated gas is connected into the pipeline by opening the second stagnation valve, the first pressure reducing valve is used for reducing the pressure of the calibrated gas from high pressure to medium pressure, and the second pressure reducing valve is used for reducing the pressure of the calibrated gas from medium pressure to normal pressure; the constant-temperature water bath circulating equipment is used for providing constant-temperature circulating water for the pipeline, the back pressure type pressure regulating valve is used for carrying out pressure fluctuation control and safety protection on the precise dew-point instrument, and the precise dew-point instrument is used for carrying out dew-point calibration on the calibrated gas. According to the invention, pressure reduction without water loss can be realized, and effective calibration of the dew point of the high-pressure low-humidity gas is realized.

Description

Technical Field

[0001] The invention belongs to the field of thermal metrology, and in particular relates to a high-pressure and low-humidity gas dew point calibration device and method. Background Art

[0002] The dew point temperature of a gas (hereinafter referred to as gas dew point) is one of the important parameters in thermal measurement. The dew point temperature directly reflects the water content in the gas. Therefore, the accurate measurement and calibration of the gas dew point is of great significance to the instruments and equipment used in many fields such as national defense, medical treatment, and chemical industry. At present, the gas dew point calibration method mostly uses a precision dew point meter as a standard instrument. The calibration method is to input the calibrated gas into the precision dew point meter to obtain the calibration value. However, most of the current precision dew point meters require the input gas pressure to be at normal pressure, which makes it impossible to directly calibrate the high-pressure gas. The high-pressure gas must be placed in the atmosphere to reduce the pressure to normal pressure, and then connected to the precision dew point meter. In the above decompression process, due to the change in pressure, there is a certain loss of water in the gas, which makes the calibration result of the precision dew point meter have a large error.

[0003] High-pressure gas is widely used in many industrial fields, especially in the defense field. In such scenarios, in order to prevent moisture from corroding electronic components or pipelines in instruments and equipment, the gas used usually has very little water content and is high-pressure, low-humidity gas. Since dew point calibration can only be performed under normal pressure conditions, it is impossible to effectively calibrate high-pressure, low-humidity gas, resulting in many gases that meet the dew point requirements under normal pressure quickly condensing after pressurization, causing corrosion to instruments and equipment in many key areas, seriously affecting their service life. Summary of the invention

[0004] The purpose of the present invention is to address the problem that current precision dew point instruments cannot directly calibrate high-pressure, low-humidity gases, and to provide a high-pressure, low-humidity gas dew point calibration device and method, which can achieve decompression without water loss and realize effective calibration of the dew point of high-pressure, low-humidity gases.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a high-pressure and low-humidity gas dew point calibration device, comprising a dry gas source, a first stop valve, a second stop valve, a first pressure reducing valve, a second pressure reducing valve, a constant temperature water bath circulation device, a back pressure regulating valve, a precision dew point meter and a pipeline, wherein the first pressure reducing valve, the second pressure reducing valve, the back pressure regulating valve and the precision dew point meter are sequentially arranged on the pipeline, and the pipeline is a three-layer casing structure, wherein the innermost layer is a gas path, the middle layer is a constant temperature circulation water path, and the outermost layer is a thermal insulation layer;

[0006] The dry gas source is used to provide dry gas to purge the pipeline to prevent water molecules attached to the pipeline from entering the calibrated gas and affecting the calibration result. The dry gas is connected to the pipeline by opening the first stop valve;

[0007] The calibrated gas is connected to the pipeline by opening the second stop valve. The first pressure reducing valve is used to reduce the pressure of the calibrated gas from high pressure to medium pressure, and the second pressure reducing valve is used to reduce the pressure of the calibrated gas from medium pressure to normal pressure. The gas path before the first pressure reducing valve is a high-pressure gas path, the gas path between the first pressure reducing valve and the second pressure reducing valve is a medium-pressure gas path, and the gas path after the second pressure reducing valve is a normal-pressure gas path;

[0008] The constant temperature water bath circulation equipment provides constant temperature circulating water for the constant temperature circulating water circuit, which is used to adjust and control the temperature of the gas circuit. The back pressure regulating valve is used to control the pressure fluctuation and provide safety protection for the precision dew point meter. The precision dew point meter is used to calibrate the dew point of the calibrated gas.

[0009] Preferably, the high-pressure gas circuit and the normal-pressure gas circuit adopt a straight-through pipe structure to allow the calibrated gas to pass quickly to avoid excessive temperature increase of the calibrated gas; the medium-pressure gas circuit adopts a coil structure to allow the calibrated gas to fully exchange heat with the constant temperature circulating water circuit, control the temperature of the calibrated gas near room temperature, and avoid changes in dew point due to temperature fluctuations after the calibrated gas enters the normal-pressure gas circuit.

[0010] Another aspect of the present invention provides a high-pressure, low-humidity gas dew point calibration method, which uses the above-mentioned device to calibrate the dew point of high-pressure, low-humidity gas, including:

[0011] Purging step: close the second stop valve, use a constant temperature water bath circulation device to raise the temperature of the pipeline to the specified temperature and stabilize it, then open the dry gas source and the first stop valve, use dry gas to purge the pipeline, and close the dry gas source and the first stop valve after the reading of the precision dew point meter stabilizes;

[0012] Calibration steps: Use a constant temperature water bath circulation device to lower the pipeline temperature to the specified temperature and stabilize it, then open the second stop valve and connect the calibrated gas to the pipeline. The calibrated gas is reduced in pressure by the first and second pressure reducing valves to reduce the pressure to normal pressure and then transported to the precision dew point meter for calibration. The dew point temperature value of the calibrated gas is obtained by reading the precision dew point meter.

[0013] Preferably, the upper limit of the initial calibration pressure of the calibrated gas is 10 MPa. After passing through the first pressure reducing valve, the pressure is reduced to one tenth of the initial pressure, and after passing through the second pressure reducing valve, the pressure is reduced to normal pressure.

[0014] Preferably, in the purging step, the pipeline is heated to 50° C. using a constant temperature water bath circulation device, and in the calibration step, the pipeline is cooled to room temperature using a constant temperature water bath circulation device.

[0015] The high-pressure, low-humidity gas dew point calibration device and method according to the above aspects of the present invention can realize decompression without water loss, thereby achieving effective calibration of the dew point of high-pressure, low-humidity gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0017] Figure 1 It is a structural schematic diagram of a high-pressure and low-humidity gas dew point calibration device according to an embodiment of the present invention;

[0018] Figure 2 It is a schematic diagram of a three-layer casing structure of a pipeline according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] An embodiment of the present invention provides a high pressure and low humidity gas dew point calibration device, such as Figure 1 As shown, the high-pressure and low-humidity gas dew point calibration device according to the embodiment of the present invention includes a dry gas source 1, a first stop valve 2, a second stop valve 3, a first pressure reducing valve 4, a second pressure reducing valve 5, a constant temperature water bath circulation device 6, a back pressure regulating valve 8, a precision dew point meter 9 and a pipeline, and the first pressure reducing valve 4, the second pressure reducing valve 5, the back pressure regulating valve 8 and the precision dew point meter 9 are arranged on the pipeline in sequence.

[0021] like Figure 2 As shown, the pipeline adopts a three-layer casing structure, the innermost layer is the air circuit, the middle layer is the constant temperature circulating water circuit, and the outermost layer is the insulation layer.

[0022] The dry gas source 1 is used to provide dry gas to purge the pipeline before calibration to prevent water molecules attached to the pipeline from entering the calibrated gas and affecting the calibration result. The dry gas is connected to the pipeline by opening the first stop valve 2.

[0023] The high-pressure and low-humidity gas to be calibrated is connected to the pipeline by opening the second stop valve 3, and the two-stage pressure reducing valve (the first pressure reducing valve 4 and the second pressure reducing valve 5) is used to reduce the pressure of the calibrated gas to normal pressure. Among them, the first pressure reducing valve 4 is used to reduce the pressure of the calibrated gas from high pressure to medium pressure, and the second pressure reducing valve 5 is used to reduce the pressure of the calibrated gas from medium pressure to normal pressure. The gas path before the first pressure reducing valve 4 is a high-pressure gas path, the gas path between the first pressure reducing valve 4 and the second pressure reducing valve 5 is a medium-pressure gas path, and the gas path after the second pressure reducing valve 5 is a normal-pressure gas path.

[0024] The constant temperature water bath circulation device 6 is used to adjust and control the temperature of all gas circuits in the device, and the constant temperature water bath circulation device 6 provides constant temperature circulating water for the pipeline. Figure 1 In the embodiment, the constant temperature water bath circulation equipment 6 is connected to the pipeline parts of the high-pressure gas circuit, the medium-pressure gas circuit and the normal-pressure gas circuit through the equipment water circuit 7 respectively. The high-pressure gas circuit and the normal-pressure gas circuit adopt a straight-through pipe structure to allow the gas to pass quickly to avoid excessive increase in gas temperature, especially the pressure increase caused by the increase in gas temperature in the high-pressure gas circuit, which affects the safety of the device. The medium-pressure gas circuit adopts a coil structure to allow the gas to fully exchange heat with the constant temperature circulating water circuit, and control the gas temperature at around normal temperature (23°C) to avoid changes in dew point due to temperature fluctuations after the gas enters the normal-pressure gas circuit. The back-pressure regulating valve 8 is used to control pressure fluctuations and provide safety protection for the precision dew point meter 9. The precision dew point meter 9 is used as a calibration standard to calibrate the dew point of the calibrated gas.

[0025] An embodiment of the present invention further provides a high-pressure, low-humidity gas dew point calibration method, which utilizes the above-mentioned device to perform dew point calibration of high-pressure, low-humidity gas, including a purging step and a calibration step.

[0026] Before starting the calibration, in the purging step, close the second stop valve 3 serving as the high-pressure wet gas input interface, open the constant temperature water bath circulation device 6, and after the overall water channel temperature is raised to the specified temperature and basically stabilized, open the switch of the dry gas source 1 and the first stop valve 2, and use dry gas to purge the entire pipeline. After the indication of the precision dew point meter 9 is basically stable, close the dry gas source 1 and the first stop valve 2.

[0027] Afterwards, in the calibration step, the constant temperature water bath circulation equipment 6 is switched to the cooling mode. After the pipeline temperature drops to the specified temperature and becomes basically stable, the second stop valve 3 is opened to connect the high-pressure gas to be calibrated to the system. The gas to be calibrated is reduced to normal pressure by the first pressure reducing valve and the second pressure reducing valve, and then transported to the precision dew point meter 9 for calibration.

[0028] In one embodiment, take the calibration of high-pressure, low-humidity gas with an initial pressure of 10 MPa as an example. Before starting the calibration, close the second stop valve 3, open the constant temperature water bath circulation device 6 and set it to 50°C, wait for about 1 hour, and after the overall gas path temperature is heated to 50°C by the circulating water and is basically stable, open the switch of the dry gas source 1 and the first stop valve 2, and use dry gas to purge the entire gas path. During the purge process, continue to observe the reading of the precision dew point meter 9, and close the dry gas source 1 and the first stop valve 2 after the reading of the precision dew point meter 9 is basically stable. Switch the constant temperature water bath circulation device 6 to the cooling mode and set it to 23°C, wait for about 1 hour, and after the overall gas path temperature drops to 23°C and is basically stable, open the second stop valve 3, and connect the high-pressure, low-humidity gas with an initial pressure of 10 MPa to the system. The pressure of the measured gas is reduced to 1MPa after passing through the first pressure reducing valve 4, and is reduced to normal pressure, i.e., about 0.1MPa, after passing through the second pressure reducing valve 5. The gas is connected to the precision dew point meter 9 for calibration, and the dew point temperature value of the current calibrated gas is obtained from the reading of the precision dew point meter.

[0029] In summary, the device of the embodiment of the present invention utilizes a double pressure reducing valve series structure, in conjunction with a constant temperature water bath circulation system, a purge system, etc., to mainly divide the gas circuit into a high-pressure gas circuit, a medium-pressure gas circuit, and a low-pressure gas circuit. The entire gas circuit is heated before the pressure reduction operation and purged under high temperature conditions. The high-pressure and normal-pressure gas circuits adopt a straight-through pipe structure to allow the gas to pass quickly to avoid excessive increases in gas temperature, especially in the high-pressure gas circuit, where the pressure increases due to the increase in gas temperature, affecting the safety of the device; the medium-pressure gas circuit adopts a coil structure to allow the gas to fully exchange heat with the constant temperature water circuit, and the gas temperature is controlled at around normal temperature (23°C), avoiding changes in the dew point caused by temperature fluctuations after the gas enters the normal-pressure gas circuit. Through the above-mentioned device and method, the measured gas has no water loss during the pressure reduction process, which meets the test needs of the precision dew point meter, and ultimately achieves high-precision measurement of the humidity parameters of high-pressure and low-humidity gas.

[0030] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high-pressure and low-humidity gas dew point calibration device, characterized in that: It includes a dry gas source, a first stop valve, a second stop valve, a first pressure reducing valve, a second pressure reducing valve, a constant temperature water bath circulation device, a back pressure regulating valve, a precision dew point meter and a pipeline. The first pressure reducing valve, the second pressure reducing valve, the back pressure regulating valve and the precision dew point meter are sequentially arranged on the pipeline. The pipeline is a three-layer casing structure, the innermost layer is the gas path, the middle layer is the constant temperature circulation water path, and the outermost layer is the insulation layer; The dry gas source is used to provide dry gas to purge the pipeline to prevent water molecules attached to the pipeline from entering the calibrated gas and affecting the calibration result. The dry gas is connected to the pipeline by opening the first stop valve; The calibrated gas is connected to the pipeline by opening the second stop valve. The first pressure reducing valve is used to reduce the pressure of the calibrated gas from high pressure to medium pressure, and the second pressure reducing valve is used to reduce the pressure of the calibrated gas from medium pressure to normal pressure. The gas path before the first pressure reducing valve is a high-pressure gas path, the gas path between the first pressure reducing valve and the second pressure reducing valve is a medium-pressure gas path, and the gas path after the second pressure reducing valve is a normal-pressure gas path; The constant temperature water bath circulation equipment provides constant temperature circulating water for the constant temperature circulating water circuit, which is used to adjust and control the temperature of the gas circuit. The back pressure regulating valve is used to control the pressure fluctuation and provide safety protection for the precision dew point meter. The precision dew point meter is used to calibrate the dew point of the calibrated gas.

2. The device according to claim 1, characterized in that The high-pressure gas circuit and the normal-pressure gas circuit adopt a straight-through pipe structure to allow the calibrated gas to pass quickly to avoid excessive temperature increase of the calibrated gas; the medium-pressure gas circuit adopts a coil structure to allow the calibrated gas to fully exchange heat with the constant temperature circulating water circuit, and control the calibrated gas temperature near room temperature to avoid changes in dew point due to temperature fluctuations after the calibrated gas enters the normal-pressure gas circuit.

3. A high pressure and low humidity gas dew point calibration method, characterized in that: The dew point calibration of high pressure and low humidity gas is performed using the device according to claim 1 or 2, comprising: Purging step: close the second stop valve, use a constant temperature water bath circulation device to raise the temperature of the pipeline to the specified temperature and stabilize it, then open the dry gas source and the first stop valve, use dry gas to purge the pipeline, and close the dry gas source and the first stop valve after the reading of the precision dew point meter stabilizes; Calibration steps: Use a constant temperature water bath circulation device to lower the pipeline temperature to the specified temperature and stabilize it, then open the second stop valve and connect the calibrated gas to the pipeline. The calibrated gas is reduced in pressure by the first and second pressure reducing valves to reduce the pressure to normal pressure and then transported to the precision dew point meter for calibration. The dew point temperature value of the calibrated gas is obtained by reading the precision dew point meter.

4. The method according to claim 3, characterized in that The upper limit of the initial calibration pressure of the calibrated gas is 10MPa. After passing through the first pressure reducing valve, the pressure is reduced to one tenth of the initial pressure, and after passing through the second pressure reducing valve, the pressure is reduced to normal pressure.

5. The method according to claim 3 or 4, characterized in that: During the purge step, the pipeline was heated to 50°C using a constant temperature water bath circulation device, and during the calibration step, the pipeline was cooled to room temperature using a constant temperature water bath circulation device.

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