A method and a special device for obtaining stable humid air flow with different dew point values

Abstract

The present invention discloses a method for obtaining a stable wet gas flow with different dew point values ​​and a special device thereof, wherein two groups of Venturi nozzles are provided, respectively used for conveying dry gas and wet gas, wherein at least one group includes no less than two Venturi nozzles, and through combination, the flow rate regulation resolution of the group of Venturi nozzles can be as low as 1mL / min, so that under the maximum flow rate, with the help of a control system for controlling the switch of the Venturi nozzle, any flow rate ratio of dry and wet gas flow can be achieved. The present invention can accurately control the pressure of the entire system, keep the flow rate constant, effectively avoid the wet gas flow caused by the pressure change of the downstream instrument under test from being normally merged into the dry gas flow, can be used to generate stable wet gas with a set dew point, the air flow rate is constant and accurate, and can be used as a standard source to verify, calibrate or set the value of the dew point measurement equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of metrology and verification, and relates to a method for obtaining a stable humid air flow, and in particular to a method for obtaining a stable humid air flow with different dew point values ​​and a special device thereof. Background Art

[0002] Humidity generating devices are widely used in the verification and calibration of humidity measuring devices such as chilled mirror dew point meters, humidity sensors, RC dew point meters, and electrolytic dew point meters. They are essential instruments for verification and calibration in the field of humidity measurement.

[0003] Humidity calibration takes a long time, and each instrument needs one day to complete the calibration. The split-flow humidity generator has the advantage of fast balancing speed, which can greatly improve the calibration efficiency and shorten the time, so the split-flow humidity generator is widely used.

[0004] The commonly used split-flow humidity generating devices, including flow controllers, saturators, and solenoid valves, are easily affected by downstream pressure, resulting in large deviations between the dew point and the set value. When the dew point in the low humidity range occurs, the ratio of dry and wet airflows is very different. If the air resistance of the downstream instrument under test is too large, the wet air flow will drop sharply and deviate from the set value, and it will not be able to mix normally with the dry air, resulting in the phenomenon that the dew point in the low humidity range cannot occur. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for obtaining a stable humid air flow with different dew point values ​​and a special device thereof.

[0006] To solve the above problems, the present invention adopts the following technical solutions:

[0007] The device of the present invention utilizes the characteristic that after maintaining the pressure ratio at a certain threshold, the pressure at the outlet end is reduced while the flow rate remains unchanged. With the help of multiple Venturi nozzles arranged in parallel, multi-point adjustment is performed, and the air flow rate can be ratio-converted according to a resolution of 1 mL / min, thereby effectively controlling its flow rate, solving the problem that the flow rate of the mass flow controller is affected by the downstream pressure, so that the flow rate of the dry and wet airflows remains constant, ensuring the constant moisture dew point value of the output port.

[0008] Calculate the saturated vapor pressure based on the saturation temperature:

[0009]

[0010] Where:

[0011] : saturation temperature, K;

[0012] : Saturated water vapor pressure in the saturator, Pa.

[0013] Calculate relative humidity based on the split ratio and saturated water vapor pressure:

[0014]

[0015] Where:

[0016] H : relative humidity, %RH;

[0017] r : split ratio;

[0018] p : total pressure in the saturator, Pa;

[0019] : Saturated water vapor pressure in the saturator, Pa.

[0020] Calculate moisture vapor pressure based on relative humidity and saturated water vapor pressure:

[0021]

[0022] Where:

[0023] : Moisture vapor pressure, Pa.

[0024] Calculate the moisture dew point temperature based on the moisture vapor pressure:

[0025]

[0026] Where:

[0027] : Dew point temperature of moist air, K.

[0028] According to the above formula, the split ratio can be calculated. When the dry or wet gas flow rate is constant, the flow value of the other gas can be calculated. By opening the solenoid valves before and after the Venturi nozzle and selecting the Venturi nozzle of the corresponding flow rate, the wet gas with the set dew point can be obtained.

[0029] The present invention relates to a method for obtaining a stable humid air flow with different dew point values, and the steps are as follows:

[0030] 1) Assemble a special device: With the help of pipelines, the gas source, the pressure reducing valve, the flow controller, the mixing chamber and the output gas path are connected in sequence; the flow controller is a dry / wet gas delivery flow control device arranged in parallel, the dry gas flow control device is a Venturi nozzle, and the wet gas flow control device is a Venturi nozzle and a saturator arranged in series, wherein at least one gas flow control Venturi nozzle includes no less than two Venturi nozzles, each of which is provided with a solenoid valve for controlling its switch and a pressure regulating device for regulating the pressure value of its front and rear ends, and the flow regulation resolution of the group of Venturi nozzles is 1ml / min; the Venturi nozzle is placed in a pre-heating temperature control device to heat the airflow it delivers to a preset temperature; the saturator and the mixing chamber are placed in a saturation temperature control device to ensure that the airflow flowing through the two can reach a predetermined saturation efficiency;

[0031] 2) Calculate the saturation temperature, set the preheating temperature of the preheating temperature control device and the saturation temperature control device according to the temperature value, and heat to the temperature;

[0032] 3) Calculate the output pressure of the gas source based on the threshold and atmospheric pressure, open the gas cylinder, and use the pressure reducing valve to reduce the output pressure to this value;

[0033] 4) Set the wet gas dew point value; fix the flow rate of either dry or wet gas as needed, and open the corresponding Venturi nozzle; calculate the flow rate of the other gas according to the set wet gas dew point value and fixed flow value, open the corresponding combination of Venturi nozzles, and adjust the pressure ratio of the front and rear ends to reach the threshold value. The output airflow is a stable wet airflow with the set wet dew point value;

[0034] 5) Change the moisture dew point value. Recalculate the flow rate of another gas based on the changed moisture dew point value and the fixed flow value. Open the corresponding combination of Venturi nozzles and adjust the pressure ratio of the front and rear ends to reach the threshold value. The output airflow is the moisture at the changed moisture dew point value.

[0035] The present invention relates to a method for obtaining a stable wet air flow with different dew point values, which is characterized in that: the special device also includes a molecular dryer, which is located between the pressure reducing valve and the flow controller; after the air source is depressurized by the pressure reducing valve, before entering the air flow conveying device, the air source is subjected to secondary water absorption and drying with the help of the molecular dryer.

[0036] The present invention relates to a method for obtaining a stable wet air flow with different dew point values, characterized in that the special device also includes a controller connected to the solenoid valve for automatically adjusting and controlling the flow of the adjustable flow Venturi nozzle group.

[0037] The present invention relates to a special device for obtaining a method for obtaining a stable wet gas flow with different dew point values, comprising an air source, a pressure reducing valve, a pressure regulating device, a flow controller, a saturator, a solenoid valve and an output air path connected by a pipeline, wherein the pressure regulating device is used to adjust the pressure value at the front and rear ends of the flow controller, and the solenoid valve is used to control the switch of the flow controller, and is characterized in that: it also includes a temperature control device and a mixing chamber; the temperature control device is composed of a pre-heating temperature control device and a saturation temperature control device; the flow controller is a Venturi nozzle, which is located in the pre-heating temperature control device so that the gas it delivers The flow is heated to a preset temperature; the saturator and the mixing chamber are located in the saturation temperature control device to ensure that the airflow flowing through the two can reach a predetermined saturation efficiency; the Venturi nozzles are arranged in parallel and are divided into two groups, which are used for dry / wet gas transportation respectively. The Venturi nozzles used for dry gas transportation enter the output gas path through the mixing chamber with the help of a pipeline, and the Venturi nozzles used for wet gas transportation enter the output gas path through the saturator and the mixing chamber in sequence with the help of a pipeline; among the two groups of Venturi nozzles, at least one group contains no less than two Venturi nozzles, and the flow adjustment resolution of the group of Venturi nozzles is 1ml / min.

[0038] The invention relates to a special device for obtaining a method for obtaining a stable wet air flow with different dew point values, characterized in that the special device also includes a molecular sieve dryer located after the pressure reducing valve and before the flow controller.

[0039] The invention relates to a special device for obtaining a method for obtaining a stable wet air flow with different dew point values, characterized in that the special device also includes a controller for automatically adjusting and controlling the flow of an adjustable flow Venturi nozzle group, which is connected to the solenoid valve.

[0040] The present invention relates to a special device for obtaining a method for obtaining a stable wet air flow with different dew point values, characterized in that the pre-heating temperature control device and the saturation temperature control device are an air bath thermostatic bath, a water bath thermostatic bath, or are composed of a heating belt and insulation cotton, and the insulation cotton is located outside the heating belt.

[0041] The present invention relates to a special device for obtaining a method for obtaining a stable wet air flow with different dew point values, characterized in that the pre-heating temperature control device is an air bath thermostatic bath, and the saturation temperature control device is a water bath thermostatic bath.

[0042] The present invention has the following beneficial technical effects:

[0043] The present invention discloses a special device for obtaining a method for obtaining a stable wet gas flow with different dew point values. The Venturi nozzles of the device are provided with two groups, which are used for conveying dry gas and wet gas respectively, wherein at least one group includes no less than two Venturi nozzles. The flow rate regulation resolution of the group of Venturi nozzles can be as low as 1 mL / min, so that under the maximum flow rate, with the help of a control system for controlling the switch of the Venturi nozzle, any flow rate ratio of the dry and wet gas flow can be achieved; a pressure regulator is provided at the front and rear ends of the Venturi nozzle, which is used to adjust the pressure ratio between the front and rear ends of the Venturi nozzle so that the pressure ratio reaches a threshold value, so as to make the flow rate of the Venturi nozzle constant; in order to avoid the flow rate of the Venturi nozzle being significantly affected by the temperature, the Venturi nozzle is placed in a pre-heating temperature control device, and the flow rate deviation is reduced by accurately adjusting the external temperature of the Venturi nozzle. At the same time, the pre-heating temperature control device can also avoid the phenomenon of the throttling effect of the Venturi nozzle causing the gas velocity at the gas flow outlet to be accelerated, resulting in a sharp drop in gas temperature, disturbing the thermal balance in the saturator, and causing a sudden change in saturation rate. The saturator is used to humidify the airflow so that it reaches a saturated state. The higher the saturation rate, the smaller the uncertainty of the humidity generator. By placing it in a saturation temperature control device, the temperature of the saturator can be controlled to ensure the consistency of the saturation rate. In addition, since the dew point of the airflow after exiting the saturator is relatively high, condensation will occur if it is higher than the ambient temperature, causing the dew point value of the wet airflow to change. Therefore, the pipeline and mixing chamber after exiting the saturator are placed in a saturation temperature control device together to prevent the saturation rate of the wet airflow from decreasing.

[0044] The present invention can accurately control the pressure of the entire system to keep the flow constant, effectively avoiding the inability of the wet air flow to merge normally into the dry air flow caused by the pressure change of the downstream instrument under test, and can be used to generate stable wet air with a set dew point. The air flow is constant and accurate, and can be used as a standard source to verify, calibrate or set the value of dew point measurement equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structural principle of the present invention.

[0046] 1. Pressure reducing valve, 2. Gas cylinder, 3. Molecular sieve dryer, 4. Pressure regulating device, 5. Preheating temperature control device, 6. Venturi nozzle, 7. Solenoid valve, 8. Saturation temperature control device, 9. Saturator, 10. Mixing chamber, 11. Output gas path. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the embodiments and drawings, but they are not intended to limit the content of the invention.

[0048] Embodiment 1

[0049] The split-flow humidity generating device of this embodiment is suitable for the case where the dry gas flow is constant and the wet gas flow is adjustable, and includes a gas source, a pressure reducing valve 1, a molecular sieve dryer 3, a pressure regulating device, a venturi nozzle 6, a control system, a temperature control device, a saturator 9, a mixing chamber 10, an output gas path 11 and a pressure sensor, such as Figure 1 shown.

[0050] The gas source is gas cylinder 2.

[0051] The pressure regulating device 4 is a pressure regulator.

[0052] There are nine Venturi nozzles 6, eight of which are used to deliver wet airflow, and their flow rates are 1 ml / min, 2 ml / min, 4 ml / min, 8 ml / min, 16 ml / min, 32 ml / min, 64 ml / min and 128 ml / min respectively; and one is used to deliver dry airflow, and its flow rate is 1000 ml / min.

[0053] The temperature control device includes a pre-heating temperature control device 5 and a saturation temperature control device 8. The pre-heating temperature control device 5 is an air bath pre-heating constant temperature tank, wherein the air bath pre-heating constant temperature tank is composed of a cylindrical side wall and front and rear end faces with an inner diameter of 126 mm, a wall thickness of 5 mm, and a length of 110 mm, and nine mounting holes for venturi nozzles 6 are designed on the end face. The saturation temperature control device 8 is a water bath constant temperature tank.

[0054] The control system includes a controller and a solenoid valve 7. The controller is a PLC programmable logic controller. The solenoid valve 7 has nine front and nine rear valves.

[0055] Nine Venturi nozzles 6 and nine rear solenoid valves 7 are located in the air bath pre-heating thermostatic tank, wherein the Venturi nozzle 6 is fixed in parallel in the mounting hole of the air bath pre-heating thermostatic tank, and its rear end is connected to the pipeline of the rear solenoid valve 7; a heater is provided in the air bath pre-heating thermostatic tank, and a temperature sensor and a pressure sensor are provided on the side wall, and the pressure sensor is located in front of the Venturi nozzle 6 to measure the front end pressure of the Venturi nozzle 6. The saturator 9 and the mixing chamber 10 are located in the water bath thermostatic tank.

[0056] By means of a pipeline made of stainless steel and having an inner diameter of 4 mm, the gas cylinder 2 is connected to the pressure reducing valve 1, the molecular sieve dryer 3, the pressure regulator, the front solenoid valve 7, the venturi nozzle 6 and the rear solenoid valve 7 in sequence, wherein the pressure regulator, the front solenoid valve 7, the venturi nozzle 6 and the rear solenoid valve 7 are in a one-to-one correspondence, and the front and rear solenoid valves 7 of each venturi nozzle 6 are connected to the same pin of the PLC programmable logic controller, and the on-off of the solenoid valve 7 is controlled by the on-off of the PLC pin; the pressure at the front end of the venturi nozzle 6 is raised by adjusting the pressure regulator, so that the pressure ratio of the front and rear ends is stabilized at the threshold value, thereby ensuring that the flow in the venturi nozzle 6 is in the set value state. Then the rear solenoid valve 7 corresponding to the wet air flow is connected to the saturator 9 and the mixing chamber 10 in sequence after passing through the pressure regulator; the rear solenoid valve 7 corresponding to the dry air flow is connected to the mixing chamber 10 after passing through the pressure regulator; the outlet of the mixing chamber 10 is connected to the output gas path 11.

[0057] The working principle of the split-flow humidity generating device of the present embodiment is as follows: through the pipeline, the high-purity gas in the gas cylinder 2 is reduced in pressure by the pressure reducing valve 1 and then enters the molecular sieve dryer 3, so that the moisture in the gas is fully adsorbed and the background value is less than -75°C DP; then, after the wet gas pressure is adjusted to an appropriate value by the pressure regulator, it enters the air bath pre-heating constant temperature tank whose temperature reaches a preset value through the front solenoid valve 7, passes through the venturi nozzle 6 and the rear solenoid valve 7 in sequence, and enters the saturation temperature control device 8 whose temperature reaches a preset value, wherein the wet gas flow is pressure-regulated by the pressure regulator, and after the back pressure ratio meets the critical condition, it enters the saturator 9, and after being fully humidified, it flows into the mixing chamber 10; the dry gas flow is pressure-regulated by the pressure regulator, and after the back pressure ratio meets the critical condition, it directly enters the mixing chamber 10; the dry and wet gas flows are fully mixed in the mixing chamber 10 and enter the output gas path 11.

[0058] Under the working condition that the dry gas flow rate is constant at 1000 ml / min and the threshold is 15, a method for obtaining a stable wet gas flow with different dew point values ​​using the split-flow humidity generating device of this embodiment is as follows:

[0059] 1. Turn on the air bath pre-heating thermostatic bath of the pre-heating temperature control device 5 and the saturated temperature control device 8, and set the internal temperatures of the two to 12°C and 10°C respectively through the 485 bus.

[0060] 2. Calculate the output pressure of gas cylinder 2, which is the product of atmospheric pressure and the threshold value, which is 1.5 bar; open the valve of gas cylinder 2 and rotate pressure reducing valve 1 to make the output air flow pressure reach 1.5 bar.

[0061] 3. Set the wet gas dew point value of -50℃ DP; open the front and rear solenoid valves 7 of the Venturi nozzle 6 for dry gas delivery, so that the dry gas flow rate is delivered at a constant speed of 1000ml / min; the controller, based on the saturation temperature of 10℃, the wet gas dew point value of -50℃ DP and the dry gas flow rate of 1000ml / min, calculates the corresponding wet gas flow rate of 9ml / min through formulas (1)-(4), opens two Venturi nozzles 6 for wet gas delivery with flow values ​​of 1ml / min and 8ml / min respectively, and the front and rear solenoid valves 7; adjusts the pressure regulator so that the front and rear pressure ratio of the two opened Venturi nozzles 6 for wet gas delivery reaches the threshold value of 15; then the airflow output by the final output gas path 11 is wet gas with a DP of -50℃.

[0062] 4. If the moisture dew point value needs to be changed to -40℃DP, set the moisture dew point value of -40℃DP; the controller, based on the known -40℃DP moisture dew point value and the dry gas flow rate of 1000ml / min, calculates the corresponding moisture flow rate of 31ml / min through formulas (1)-(4), and opens six Venturi nozzles 6 with flow values ​​of 1ml / min, 2ml / min, 4ml / min, 8ml / min and 16ml / min, and the solenoid valves 7 before and after them; adjust the pressure regulator so that the front and rear pressure ratio of the two opened Venturi nozzles 6 for moisture transport reaches the threshold value of 15; then the gas flow output by the final output gas path 11 is the moisture at -40℃DP.

[0063] 5. When shutting down, first close the valve of gas cylinder 2, rotate the pressure reducing valve 1, and close the air flow. Turn off the preheating temperature control device 5 and the constant temperature bath 8. Finally, turn off the solenoid valve 7 and the pressure regulator and controller.

[0064] Embodiment 2

[0065] The split-flow humidity generating device of this embodiment is suitable for the situation where the wet gas flow is constant and the dry gas flow is adjustable, and includes an air source, a pressure reducing valve 1, a pressure regulating device, a Venturi nozzle 6, a control system, a temperature control device, a saturator 9, a mixing chamber 10, an output air path 11 and a pressure sensor.

[0066] The gas source is gas cylinder 2.

[0067] The pressure regulating device 4 is a pressure setter.

[0068] There are seven Venturi nozzles 6, of which six are used to deliver dry airflow, and their flow rates are 1 ml / min, 2 ml / min, 4 ml / min, 8 ml / min, 16 ml / min and 32 ml / min respectively; and one is used to deliver wet airflow, and its flow rate is 800 ml / min.

[0069] The temperature control device includes a pre-heating temperature control device 5 and a saturation temperature control device 8. The pre-heating temperature control device 5 is a water bath pre-heating constant temperature tank, which is composed of a cylindrical side wall and front and rear end faces with an inner diameter of 150 mm, a wall thickness of 8 mm, and a length of 120 mm, and seven mounting holes for venturi nozzles 6 are designed on the end face. The saturation temperature control device 8 includes a heating belt and heat insulation cotton, and the heat insulation cotton is located outside the heating belt.

[0070] The control system includes a controller and a solenoid valve 7. The controller is a single chip microcomputer. The solenoid valve 7 has six front and six rear valves.

[0071] Seven Venturi nozzles 6 and six rear solenoid valves 7 are located in the water bath pre-heating thermostatic tank, wherein the Venturi nozzles 6 are fixed in parallel in the mounting holes of the water bath pre-heating thermostatic tank, and the rear end of the Venturi nozzle 6 for conveying dry air flow is connected to the pipeline of the rear solenoid valve 7; the pressure sensor is located in front of the Venturi nozzle 6, and is used to measure the front end pressure of the Venturi nozzle 6. The saturator 9 and the mixing chamber 10 are located in the saturation temperature control device 8.

[0072] With the help of a pipeline made of copper steel with an inner diameter of 6 mm, the gas cylinder 2 is connected to the front solenoid valve 7, the Venturi nozzle 6 for conveying dry air flow, the rear solenoid valve 7, the pressure setter, the saturator 9 and the mixing chamber 10 in sequence through the pressure reducing valve 1 and the pressure setter, wherein the pressure setter, the front solenoid valve 7, the Venturi nozzle 6 and the rear solenoid valve 7 are in a one-to-one correspondence, and the front and rear solenoid valves 7 of each Venturi nozzle 6 are connected to the same pin of the single-chip microcomputer, and the on-off of the solenoid valve 7 is controlled by the on-off of the pin of the single-chip microcomputer; the other route is connected to the Venturi nozzle 6 for conveying wet air flow, the pressure setter, and the mixing chamber 10 in sequence; the outlet of the mixing chamber 10 is connected to the output gas path 11.

[0073] Embodiment 3

[0074] The difference from the first embodiment is that:

[0075] There are sixteen Venturi nozzles 6 in total, eight for dry gas delivery and eight for wet gas delivery, and the flow rates are 1 ml / min, 2 ml / min, 4 ml / min, 8 ml / min, 16 ml / min and 32 ml / min respectively.

Claims

1. A method for obtaining a stable humid air flow with different dew point values, the steps of which are as follows: 1) Assembling a dedicated device: the gas source, the pressure reducing valve (1), the flow controller, the mixing chamber (10) and the output gas path (11) are connected in sequence by means of pipelines; the flow controller is a dry / wet gas delivery flow control device arranged in parallel, the dry gas flow control device is a Venturi nozzle (6), and the wet gas flow control device is a Venturi nozzle (6) and a saturator (9) arranged in series, in, At least one venturi nozzle (6) for gas flow control comprises at least two venturi nozzles (6), each venturi nozzle (6) being provided with a solenoid valve (7) for controlling its switch and a pressure regulating device (4) for regulating the pressure value at the front and rear ends thereof, and the flow regulation resolution of the group of venturi nozzles (6) being 1 ml / min; the venturi nozzle (6) being placed in a preheating temperature control device (5) so that the airflow it delivers is heated to a preset temperature; the saturator (9) and the mixing chamber (10) being placed in a saturation temperature control device (8) so as to ensure that the airflow flowing through the two can reach a predetermined saturation efficiency; the dedicated device further comprises a controller connected to the solenoid valve (7) for automatically regulating and controlling the flow of the group of venturi nozzles (6); 2) setting the preheating temperature of the preheating temperature control device (5) and the saturation temperature control device (8), and heating to the preheating temperature; 3) Calculate the output pressure of the gas source according to the threshold value and the atmospheric pressure, open the gas cylinder (2), and reduce the output pressure to the value by means of the pressure reducing valve (1); 4) Set the moisture dew point value; The flow rate of any one of the dry or wet gases is fixed as required, and the corresponding venturi nozzle (6) is opened; the flow rate of the other gas is calculated according to the set wet gas dew point value and the fixed flow value, the corresponding combination of venturi nozzles (6) is opened, and the pressure ratio of the front and rear ends thereof is adjusted to reach a threshold value, and the output airflow is a stable wet airflow of the set wet gas dew point value; 5) The moisture dew point value is changed. According to the changed moisture dew point value and the fixed flow value, the flow rate of another gas is recalculated, the corresponding combination of Venturi nozzles (6) is opened, and the pressure ratio of the front and rear ends thereof is adjusted to reach a threshold value, and the output air flow is the moisture of the changed moisture dew point value.

2. The method for obtaining a stable humid air flow with different dew point values ​​according to claim 1, Features: The special device also includes a molecular dryer (3) located between the pressure reducing valve (1) and the flow controller; after the air source is decompressed by the pressure reducing valve (1), before entering the air flow conveying device, the molecular dryer (3) is used for secondary water absorption and drying.

3. A special device for the method of obtaining a stable wet gas flow with different dew point values ​​as claimed in claim 1, comprising an air source, a pressure reducing valve, a pressure regulating device, a flow controller, a saturator, a solenoid valve and an output air path connected by a pipeline, wherein the pressure regulating device is used to adjust the pressure value at the front and rear ends of the flow controller, and the solenoid valve is used to control the switch of the flow controller. Features: The invention also comprises a temperature control device and a mixing chamber (10); the temperature control device is composed of a preheating temperature control device (5) and a saturation temperature control device (8); the flow controller is a venturi nozzle (6) located in the preheating temperature control device (5) so as to heat the airflow it conveys to a preset temperature; the saturator (9) and the mixing chamber (10) are located in the saturation temperature control device (8) so as to ensure that the airflow flowing through the two can reach a predetermined saturation efficiency; the venturi nozzles (6) are arranged in parallel and divided into two groups, which are used for dry gas and wet gas conveying respectively. The venturi nozzles (6) used for dry gas conveying enter the output gas path through the mixing chamber (10) via a pipeline, and the venturi nozzles (6) used for wet gas conveying enter the output gas path through the saturator (9) and the mixing chamber (10) via a pipeline in sequence; of the two groups of venturi nozzles (6), at least one group comprises no less than two venturi nozzles (6), and the flow adjustment resolution of the venturi nozzles (6) in the group is 1 ml / min.

4. The dedicated device for obtaining a method for obtaining a stable humid air flow with different dew point values ​​according to claim 3, Features: The special device also includes a molecular sieve dryer (3), which is located after the pressure reducing valve (1) and before the flow controller.

5. The dedicated device for obtaining a stable humid air flow with different dew point values ​​according to claim 3, Features: The special device also includes a controller for automatically adjusting and controlling the flow rate of the adjustable flow rate Venturi nozzle (6) group, which is connected to the solenoid valve (7).

6. The dedicated device for obtaining a method for obtaining a stable humid air flow with different dew point values ​​according to claim 3, Features: The preheating temperature control device (5) and the saturation temperature control device (8) are air bath thermostatic baths, water bath thermostatic baths, or are composed of heating belts and heat insulation cotton, and the heat insulation cotton is located outside the heating belts.

7. The dedicated device for obtaining a stable humid air flow with different dew point values ​​according to claim 6, Features: The preheating temperature control device (5) is an air bath thermostatic bath, and the saturation temperature control device (8) is a water bath thermostatic bath.

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