CN211636047U - Device for producing low-concentration standard gas mixture - Google Patents
Device for producing low-concentration standard gas mixture Download PDFInfo
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- CN211636047U CN211636047U CN201920682946.9U CN201920682946U CN211636047U CN 211636047 U CN211636047 U CN 211636047U CN 201920682946 U CN201920682946 U CN 201920682946U CN 211636047 U CN211636047 U CN 211636047U
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Abstract
The utility model provides a device for producing low-concentration standard gas mixture. The apparatus for producing a low concentration standard gas mixture includes: the device comprises a diffusion chamber, a diffusion pipe, a thermostatic bath, a fan and a gas storage tank, wherein a lower diffusion chamber filled with a liquid carried target substance is provided in the thermostatic bath with controlled temperature, saturated steam is filled in a space above the liquid in the diffusion chamber, the upper diffusion chamber and the lower diffusion chamber are connected through the diffusion pipe, carrier gas airflow with preset flow passes through the upper diffusion chamber through a pipeline, the steam enters the upper diffusion chamber through the diffusion pipe and is fully mixed with the airflow, and a carried target substance gas mixture with required concentration is obtained.
Description
Technical Field
The utility model relates to a standard gas mixture produces technical field, more specifically relates to a device of production low concentration standard gas mixture.
Background
In many industrial applications and research, there is an increasing demand for low concentrations of standard gases, but formulations based on pure gas dilution are not always satisfactory. Currently, the preparation of low concentration standard gas mixtures is mainly carried out by both static and dynamic methods. The static method is to prepare a desired mixture of a certain concentration by using weighing or pressure and then to hold it in a container for use. A dynamic process is one in which the target substance is introduced into a stream of pure carrier gas at essentially atmospheric pressure to achieve the desired concentration and then used in a particular application. The utility model discloses a gaseous configuration method be a dynamic method, and its principle is that the lower diffusion room that utilizes the liquid target material of dress to arrange in under certain temperature, pressure, and this material diffusivity remains unchanged, flows through the standard gas of diffusion room in order to obtain required concentration through carrier gas continuous and stable.
The diffusion tube generating device for producing the standard gas substance has the advantages that the diffusion tube generating device can be used for producing the standard gas substance which is unstable in gas cylinders in adsorbability, corrosivity and the like, such as low-content gas mixture of sec-butyl alcohol, chlorobenzene, aniline and the like, the gas mixture is unstable in a static container sometimes, and the stable and reliable standard gas can be produced on site by using a diffusion tube method for industrial application and research. The diffusion tube method is widely applied to various enterprises, scientific research institutions and other institutions at present, and relates to various fields of chemical industry, environment, medical treatment and the like.
However, when a standard gas with a low concentration is produced by the prior art techniques and methods, there is not a small deviation between the concentration obtained after mixing the carrier gas and the gaseous target substance to be carried and the theoretically calculated concentration.
Disclosure of Invention
In order to obtain the standard gas mixture of 0.1 ~ 100ppm concentration range, satisfy the needs of numerous applications and research at present, the utility model provides a device of production low concentration standard gas mixture is used for disposing the gas of corresponding concentration.
The utility model discloses a solve the scheme that this technical problem adopted and be: a diffusion chamber filled with liquid carried target substance is provided in a thermostatic bath with controlled temperature, the space above the liquid in the diffusion chamber is filled with saturated steam, the upper diffusion chamber and the lower diffusion chamber are connected through a diffusion pipe, carrier gas is pressed into a gas storage tank by a fan to reduce the change of inlet pressure, carrier gas flow with preset flow rate flows through the upper diffusion chamber through a pipeline by adjusting a flow controller, and the steam enters the upper diffusion chamber through the diffusion pipe to be fully mixed with the gas flow, so that the carried target substance gas mixture with required concentration is obtained.
The carried target substance is in a liquid state, and may be, for example, sec-butyl alcohol, chlorobenzene, n-butyl alcohol, dipentanol, isopropanol, toluene, aniline, ethyl acetate, or the like.
The carrier gas is typically in a highly pure form, and may be, for example, nitrogen, helium, argon, carbon dioxide, or the like, and is typically inert with respect to the target species being carried.
The temperature of the thermostatic bath can be precisely controlled by a water bath, a heating element, and the like. The diffusivity of a particular carried target species is a function of temperature only, with a constant total pressure in the device, and can be very accurately controlled by adjusting the bath temperature to achieve the desired carried target species concentration.
Drawings
Fig. 1 is a schematic view of an apparatus for producing a low concentration standard gas mixture according to the present invention, and fig. 2 is a schematic view of a diffusion chamber in the apparatus for producing a low concentration standard gas mixture. The device comprises a fan 1, a gas storage tank 2, a control valve 3, a flow controller 4, an upper diffusion chamber and a lower diffusion chamber 5 and 6 respectively, control valves 7 and 8, diffusion pipes 9, and pipes 100mm, 160mm, 200mm and 240mm in length, wherein the diameters of the diffusion pipes can be 6mm, 8mm, 10mm, 20mm and 25 mm.
Detailed Description
The schematic diagram of the device for producing the low-concentration standard gas mixture according to the figure 1 comprises a fan (1), a gas storage tank (2), a control valve (3), a flow controller (4), an upper diffusion chamber (5), a lower diffusion chamber (6), a control valve (7), a control valve (8) and a diffusion pipe (9).
Firstly, compressing selected high-purity carrier gas such as nitrogen, helium and the like into a gas storage tank (2) through a fan (1), controlling the pressure in the gas storage tank (2) to be kept constant by controlling the fan and adjusting the flow rate of the carrier gas participating in the production process so as to reduce the influence of pressure change on the production process, then passing the carrier gas through a control valve (3) and a flow controller (4), the flow controller being capable of precisely controlling and reading the flow rate of the carrier gas, the flow controller being capable of precisely controlling the flow rate of the carrier gas to be about 10.0ml/min, about 5.0ml/min, about 0.5ml/min, about 0.1ml/min, about 0.01ml/min and the like, then flowing the carrier gas into an upper diffusion chamber (5), placing a lower diffusion chamber (6) containing a sufficient amount of liquid carried target substance such as toluene, formaldehyde and the like into a temperature-, the accuracy can be about 0.1 ℃, 0.01 ℃ and the like, the upper space is filled with saturated steam of the carried target substance, when the carrying gas fully flows into the upper diffusion chamber, the saturated steam flows into the upper diffusion chamber (5) at a constant diffusion rate through a diffusion pipe (9), and is fully mixed with the carrying gas in the upper diffusion chamber to obtain mixed gas with required concentration, and then the mixed gas is used for various applications through a control valve (8) or is exhausted through a control valve (7).
The diffusion rate of the carried target substance under the conditions determined by pressure and temperature can be calculated by the following formula:
wherein: r-diffusion rate, g/min;
m-molecular weight of the target substance to be carried;
P-Total pressure, Pa；
A-cross-sectional area of diffuser tube, m2；
L-diffusion tube length, m;
T0absolute temperature, 273K;
r-ideal gas constant, 8.314J/(mol. K);
D0diffusion coefficient at 0 ℃ and 1atm, m2/min；
P0Atmospheric pressure, 101325Pa；
P-steam pressure, Pa
π＝(P/(P-p))
The concentration of the resulting mixed gas can be calculated by the following formula:
c-theoretical concentration of standard gas, mol/mol;
r-diffusion rate, g/min;
m-molecular weight of target substance to be carried, g/mol;
f-flow through flow controller, ml/min;
r is ideal gas constant, J/(mol.K);
t is the ambient temperature at work, K;
PAambient atmospheric pressure during operation, Pa；
Taking toluene and ethyl acetate as examples, the calculation procedure is as follows:
(1) the diffusion coefficient of toluene at 0 deg.C and 1atm is 4.9749 × 10-4The molecular weight is 92g/mol, T is controlled to 52 ℃, and the saturated vapor pressure is 13.33KPaThe diameter of the diffuser pipe is 10mm and the length is 200mm, at this time
The diffusion rate is then:
the flow rate of carrier gas is 1000.0ml/min, and the theoretical concentration of the obtained mixed gas is as follows:
(2) the diffusion coefficient of toluene at 0 deg.C and 1atm is 4.9749 × 10-4The molecular weight is 92g/mol, T is controlled to 52 ℃, and the saturated vapor pressure is 13.33KPaThe diameter of the diffusion tube is 20mm, and the length of the diffusion tube is 240mm, in this case
The diffusion rate is then:
the flow rate of carrier gas is 1500.0ml/min, and the theoretical concentration of the obtained mixed gas is as follows:
(3) the diffusion coefficient of the ethyl acetate is 5.0712 × 10 under the conditions of 0 ℃ and 1atm-4The molecular weight is 88g/mol, the temperature T is controlled to be 40 ℃, and the saturated vapor pressure is 25.44KPaThe diameter of the diffuser pipe is 10mm and the length is 200mm, at this time
The diffusion rate is then:
the flow rate of carrier gas is 1000.0ml/min, and the theoretical concentration of the obtained mixed gas is as follows:
(4) the diffusion coefficient of the ethyl acetate is 5.0712 × 10 under the conditions of 0 ℃ and 1atm-4The molecular weight is 88g/mol, the temperature T is controlled to be 40 ℃, and the saturated vapor pressure is 25.44KPaThe diameter of the diffusion tube is 6mm, and the length of the diffusion tube is 240mm, at the moment
The diffusion rate is then:
the flow rate of carrier gas is 1000.0ml/min, and the theoretical concentration of the obtained mixed gas is as follows:
meets the requirements.
Claims (4)
1. An apparatus for producing a low concentration standard gas mixture for producing a standard gas mixture in a concentration range of 0.1 to 100ppm, the apparatus comprising: the device comprises two diffusion chambers, a temperature-controllable thermostatic bath, a fan and a pipeline for connecting the diffusion chambers and an air storage tank, wherein the two diffusion chambers are connected through diffusion pipes; providing a diffusion chamber filled with liquid carried target substance in a temperature-controlled thermostatic bath, filling saturated steam in the space above the liquid in the diffusion chamber, connecting the upper diffusion chamber and the lower diffusion chamber through diffusion pipes, enabling carrier gas flow with preset flow to flow through the upper diffusion chamber through a pipeline, and enabling the steam to enter the upper diffusion chamber through the diffusion pipes to be fully mixed with the gas flow to obtain a carried target substance gas mixture with required concentration.
2. The apparatus of claim 1, the temperature of the lower diffusion chamber being held constant.
3. The device of claim 1, wherein the diffuser tube may have a diameter of 6mm, 8mm, 10mm, 20mm, 25mm and a tube length of 100mm, 160mm, 200mm, 240 mm.
4. The apparatus of claim 1, further comprising a flow control valve disposed on a conduit connecting the diffusion chamber to the air reservoir.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920682946.9U CN211636047U (en) | 2019-05-14 | 2019-05-14 | Device for producing low-concentration standard gas mixture |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920682946.9U CN211636047U (en) | 2019-05-14 | 2019-05-14 | Device for producing low-concentration standard gas mixture |
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| Publication Number | Publication Date |
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| CN211636047U true CN211636047U (en) | 2020-10-09 |
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| CN201920682946.9U Expired - Fee Related CN211636047U (en) | 2019-05-14 | 2019-05-14 | Device for producing low-concentration standard gas mixture |
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2019
- 2019-05-14 CN CN201920682946.9U patent/CN211636047U/en not_active Expired - Fee Related
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Granted publication date: 20201009 Termination date: 20210514 |