阅读说明：本技术 一种气体标准物质的动态稀释配制系统以及配制方法 (Dynamic dilution preparation system and preparation method of gas standard substance ) 是由 毕哲 师耀龙 王德发 贡鸣 赵鑫蕊 马浩淼 于 2019-08-20 设计创作，主要内容包括：本发明涉及本一种气体标准物质的动态稀释配制系统以及配制方法,所述系统包括稀释气体源(10),原料气体源(20),多个流量计(30),加湿装置(40),连接管线,混合室(50),温湿度计(60),加热装置(70),稀释气体源(10)通过连接管线经由第一流量计(30-1)连接至加湿装置(40),加湿装置(40)经由连接管线连接至混合室(50)；原料气体源(20)通过连接管线经由第二流量计(30-2)连接至混合室(50)；温湿度计(60)连接至混合室(50)的出口连接管线(51)上；加湿装置(40)、混合室(50)以及温湿度计设置在所述加热装置(70)之中。(The invention relates to a dynamic dilution preparation system and a preparation method of a gas standard substance, wherein the system comprises a dilution gas source (10), a raw gas source (20), a plurality of flow meters (30), a humidifying device (40), a connecting pipeline, a mixing chamber (50), a hygrothermograph (60) and a heating device (70), the dilution gas source (10) is connected to the humidifying device (40) through the connecting pipeline via a first flow meter (30-1), and the humidifying device (40) is connected to the mixing chamber (50) via the connecting pipeline; a source of feed gas (20) is connected to the mixing chamber (50) via a second flow meter (30-2) by a connecting line; the hygrothermograph (60) is connected to an outlet connecting line (51) of the mixing chamber (50); the humidifying device (40), the mixing chamber (50) and the hygrothermograph are arranged in the heating device (70).)

1. A system for dynamic dilution dispensing of a gaseous standard, comprising:

a dilution gas source (10), a raw gas source (20), a plurality of flow meters (30), a humidifying device (40), a connecting pipeline, a mixing chamber (50), a hygrothermograph (60), a heating device (70),

the dilution gas source (10) is connected to the humidifying device (40) via a first flow meter (30-1) by a connecting line,

the humidifying device (40) is connected to the mixing chamber (50) via a connecting line;

a source of feed gas (20) is connected to the mixing chamber (50) via a second flow meter (30-2) by a connecting line;

the hygrothermograph (60) is connected to an outlet connecting line (51) of the mixing chamber (50);

the humidifying device (40), the mixing chamber (50) and the hygrothermograph are arranged in the heating device (70).

2. The system for dynamic dilution of gaseous standard substance preparation according to claim 1, wherein a third flow meter (30-3) is provided between the first flow meter (30-1) and the humidifying device (40), a connection line is led out between the first flow meter (30-1) and the third flow meter (30-3) and connected to a connection line between the humidifying device (40) and the mixing chamber (50), thereby constituting a bypass.

3. The dynamic dilution dispensing system for a gas standard according to claim 1, wherein the mixing chamber is a silanized glass mixing chamber or a 316L passivated mixing chamber.

4. The system for the dynamic dilution of a gaseous standard according to claim 1, wherein the humidifying device (40) is a secondary glass bubbler.

5. A system for the dynamic dilution of a gaseous standard according to any one of claims 1 to 4, wherein the connection lines between the aforementioned components are silanized glass lines or 316L passivated lines.

6. The system of claim 1, further comprising a control module, wherein the flow meter, the thermo-hygrometer, and the heating device are coupled to the control module.

7. A method for dynamic dilution formulation of a gaseous standard comprising a pre-purge step comprising:

a. heating the humidifying device (40) and the mixing chamber (50) to a predetermined temperature by a heating device (70);

b. closing the outlet of the mixing chamber (50), then opening the diluting gas source (10) to enable the pressure in the diluting gas path to rise to a preset pressure, and then closing the diluting gas source (10);

c. the outlet of the mixing chamber (50) is opened to vent the pressure,

d. repeating the steps b-c for a plurality of times to ensure that the obtained diluent gas path is filled with diluent gas, and then closing the diluent gas path;

e. closing the outlet of the mixing chamber (50), then opening the raw material gas source (20) to enable the pressure in the raw material gas path to rise to a preset pressure, and then closing the raw material gas source (20);

f. the outlet of the mixing chamber (50) is opened to vent the pressure,

g. and e, repeating the steps e-f for multiple times to ensure that the raw material gas path is filled with the raw material gas.

8. The method of claim 7, further comprising performing a dynamic dilution dispensing step of the gaseous standard after the pre-purging step, the dynamic dilution dispensing step comprising humidifying the dilution gas with a humidifying device (40).

9. The method of claim 7, wherein the humidifying device (40) is a secondary glass bubbler.

10. The method of claim 7, wherein the connecting lines in the diluent gas circuit and the feedstock gas circuit and the mixing chamber are silanized glass lines or 316L passivated lines.

Technical Field

The invention relates to the technical field of gas standard substances, in particular to a dynamic dilution preparation system and a preparation method of a gas standard substance.

Background

For gas components which are unstable in chemical property or low in concentration and easy to adsorb, the bottled standard gas is difficult to meet the experimental requirements, and a dynamic gas distribution method is usually required at the moment. The method enables the raw material gas with known concentration and the diluent gas to continuously enter a mixer to be mixed according to a constant proportion, thereby continuously preparing and supplying standard gas with certain concentration, calculating the dilution factor according to the flow ratio of two air flows, and then calculating the concentration of the standard gas according to the dilution factor. The dynamic gas distribution method not only can provide a large amount of standard gas, but also can obtain the standard gas with the required concentration by adjusting the flow ratio of the raw gas and the diluent gas, and the method is particularly suitable for preparing the standard gas with low concentration or reactivity.

However, the above prior art has some drawbacks, such as that for unstable gas components, such as volatile organic compounds, which tend to adsorb on the inner wall of the vessel during dilution, the amount is reduced, thereby causing deviation of the exact amount of the standard gas to be generated; for low-concentration components, due to the adsorption phenomenon, the system is often stable only by long-time purging, so that the use efficiency of a standard diluting device is greatly reduced; in addition, the main objective of the prior art is to obtain standard gases with specific concentrations, but the generated standard gases are dry gases and still have differences from real air samples, and for sensors with large humidity influence, such as electrochemical sensors or mass spectrometry and other components, the results of calibration with the dry standard gases have larger deviation from the real values.

Therefore, there is a need for new formulation techniques and equipment for gas standards.

Disclosure of Invention

In order to solve at least a part of the problems in the prior art, the technical object of the present invention is to provide a dynamic dilution preparation system and a preparation method for a gas standard substance, which can reduce the adsorption of components by the inner wall of the dilution system, reduce the purging time for the system to reach a stable concentration, improve the working efficiency of the system, control the humidity level in the standard gas, and eliminate the problems of water condensation on the inner wall of the gas mixing tank.

According to an aspect of the present invention, there is provided a dynamic dilution dispensing system for a gaseous standard substance, comprising:

a dilution gas source (10), a raw gas source (20), a plurality of flow meters (30), a humidifying device (40), a connecting pipeline, a mixing chamber (50), a hygrothermograph (60), a heating device (70),

the dilution gas source (10) is connected to the humidifying device (40) via a first flow meter (30-1) by a connecting line,

the humidifying device (40) is connected to the mixing chamber (50) via a connecting line;

a source of feed gas (20) is connected to the mixing chamber (50) via a second flow meter (30-2) by a connecting line;

the hygrothermograph (60) is connected to an outlet connecting line (51) of the mixing chamber (50);

the humidifying device (40), the mixing chamber (50) and the hygrothermograph are arranged in the heating device (70).

According to one embodiment of the present invention, a third flow meter (30-3) is provided between the first flow meter (30-1) and the humidifying device (40), a connection line is led out between the first flow meter (30-1) and the third flow meter (30-3), and is connected to the connection line between the humidifying device (40) and the mixing chamber (50), thereby constituting a bypass.

According to one embodiment of the invention, wherein the mixing chamber is a silanized glass mixing chamber or a 316L passivated mixing chamber.

According to one embodiment of the invention, wherein the heating means (70) is selected from the group consisting of gas bath heating, heating jackets and resistance wire heating.

According to one embodiment of the invention, wherein the humidifying device (40) is selected from a bubbler, a nafion humidifying tube, an ultrasonic humidifier.

According to one embodiment of the invention, wherein the humidifying device (40) is a two-stage glass bubbler.

According to one embodiment of the present invention, the connecting line between the above components is a silanized glass line or a 316L passivated line.

According to one embodiment of the invention, wherein the flow meter (30) is selected from the group consisting of a mass flow meter, a capillary flow meter, a sonic nozzle flow meter, a laminar flow meter, and an electronic needle valve flow meter.

According to one embodiment of the invention, wherein the system for dynamic dilution of a gaseous standard substance comprises further flow control valves (41) arranged on the inlet and outlet lines of the humidifying device (40) and/or on the bypass.

According to an embodiment of the present invention, the system for dynamically diluting and dispensing the gas standard substance further comprises a control module, and the flow meter, the hygrothermograph and the heating device are connected with the control module.

According to another aspect of the present invention, there is provided a method for dynamic dilution formulation of a gaseous standard, the method comprising a pre-purge step comprising:

a. heating the humidifying device (40) and the mixing chamber (50) to a predetermined temperature by a heating device (70);

b. closing the outlet of the mixing chamber (50), then opening the diluting gas source (10) to enable the pressure in the diluting gas path to rise to a preset pressure, and then closing the diluting gas source (10);

c. the outlet of the mixing chamber (50) is opened to vent the pressure,

d. repeating the steps b-c for a plurality of times to ensure that the obtained diluent gas path is filled with diluent gas, and then closing the diluent gas path;

e. closing the outlet of the mixing chamber (50), then opening the raw material gas source (20) to enable the pressure in the raw material gas path to rise to a preset pressure, and then closing the raw material gas source (20);

f. the outlet of the mixing chamber (50) is opened to vent the pressure,

g. and e, repeating the steps e-f for multiple times to ensure that the raw material gas path is filled with the raw material gas.

According to one embodiment of the invention, wherein the method further comprises a step of dynamic dilution formulation of the gaseous standard after the pre-purge step, the dynamic dilution formulation step comprising humidification of the dilution gas by means of a humidification device (40).

According to one embodiment of the invention, wherein the humidifying device (40) is a two-stage glass bubbler.

According to one embodiment of the invention, the diluent gas path is divided into two paths, wherein one path does not pass through the humidifying device (40), the other path is humidified by the humidifying device (40), and then the two paths are merged.

According to an embodiment of the present invention, wherein the connection lines in the dilution gas line and the raw gas line are silanized glass lines or 316L passivated lines.

According to one embodiment of the invention, wherein the mixing chamber is a silanized glass mixing chamber or a 316L passivated mixing chamber.

The invention adopts a passivation pipeline, thereby greatly reducing the adsorption of the inner wall of the dilution system to unstable components. Before dilution, the system is purged and cleaned, and a cleaning mode of system closed pressure-baking-emptying-purging multi-cycle is adopted, so that the purging time of the system reaching stable concentration is greatly reduced. The silanized glass gas pool or the passivation mixing chamber is adopted in the gas mixing pool (mixing chamber), both the pipeline and the gas mixing pool can be heated at controlled temperature, and the problems of inner wall adsorption, water condensation and the like of the gas mixing pool are reduced to the maximum extent. In addition, the invention adopts a method of mixing the wet gas and the dry gas according to the proportion to generate the diluent gas with specific humidity, and the diluent gas is mixed with the sample gas again to form the standard gas with certain concentration and under specific humidity and temperature, and the quantitative humidification function and the quantitative dilution function are integrated.

Drawings

The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. The objects and features of the present invention will become more apparent in view of the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a dynamic dilution dispensing system for a gaseous standard according to one embodiment of the present invention.

FIG. 2 is a schematic diagram of a control software operating interface according to one embodiment of the present invention.

Fig. 3 is a graph showing the results of a comparison experiment between the humidifying performance of a single-stage glass bottle and the humidifying performance of a double-stage glass bottle according to an embodiment of the invention.

FIG. 4 is a graph showing experimental results of the effect of system settling time for different mixer materials in accordance with one embodiment of the present invention.

FIG. 5 is a graphical representation of experimental results showing the effect of different temperatures on system stability time in accordance with one embodiment of the present invention.

Detailed Description

Specific embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings by way of illustration and not limitation.

FIG. 1 is a schematic diagram of a dynamic dilution dispensing system for a gaseous standard according to one embodiment of the present invention. Referring to fig. 1, the system for formulating a volatile organic gas standard according to the present invention may include: a dilution gas source (10), a raw material gas source (20), a plurality of flow meters (30), a humidifying device (40), a connecting pipeline, a mixing chamber (50), a hygrothermograph (60), a heating device (70), wherein the dilution gas source (10) is connected to the humidifying device (40) through the connecting pipeline via a first flow meter (30-1), and the humidifying device (40) is connected to the mixing chamber (50) via the connecting pipeline; a source of feed gas (20) is connected to the mixing chamber (50) via a second flow meter (30-2) by a connecting line; the hygrothermograph (60) is connected to an outlet connecting line (51) of the mixing chamber (50); the humidifying device (40), the mixing chamber (50) and the hygrothermograph are arranged in the heating device (70).

More specifically, the dilution gas source (10) is a carrier gas, which may be, for example, high-purity nitrogen, hydrogen, helium, or the like, loaded in a high-pressure gas cylinder as the dilution gas source (10). The diluent gas is depressurized through a first depressurization valve 11. For example, the gas pressure in the high pressure gas cylinder may be reduced to a specified range according to the user's demand. And then filtered through a filter device to further purify the carrier gas. For example, filtration may be performed using activated carbon filter 12 and 5A molecular sieve filter 13.

The purified carrier gas flows through a first flowmeter (30-1) and is then divided into two paths. One path of the water flows through a third flow meter (30-3) and a flow control valve (41) and enters a humidifying device (40) for humidifying. The other path passes through a flow control valve (41-2) without humidification. The flow meter may be selected from a mass flow meter, a capillary flow meter, a sonic nozzle flow meter, a laminar flow meter, an electronic needle valve flow meter, and the like, and may precisely control and meter the flow rate of the gas. The flow control valve (41) can be a stop valve and the like and can be used for adjusting the opening and closing degree of the air passage and opening and closing.

As shown in fig. 1, a humidifying device 40 is provided on a flow path of humidification, and flow control valves (41-1, 41-3) may be provided on inlet and outlet lines of the humidifying device (40), thereby facilitating manipulation of the humidifying device 40. The humidifying device 40 may be, for example, a bubbling bottle, a nafion humidifying pipe, an ultrasonic humidifier, etc., and two bubbling bottles connected in series are shown in the figure, and a water filling port is arranged on each bubbling bottle for facilitating water filling.

A float flow meter 42 may also be provided in the non-humidified flow path. The float meter is completely empty and only functions to indicate flow.

When the dry dilution function is required, the third flow meter 30-3, the flow control valve 41-1 and the flow control valve 41-3 are turned off to close the humidification flow path. The carrier gas is flow limited by the first flow meter 30-1 and flows at a fixed flow rate through the flow control valve 41-1 and the float flow meter 42, which is fully vented, functioning only as an indicator of flow, and then into the mixing chamber (50).

When a wet-type dilution function is needed, the first flow control valve 41-1 and the third flow control valve 41-3 are opened, the carrier gas is divided into two paths after the flow is limited by the first flow meter 30-1, wherein one path of the carrier gas is controlled by the third flow meter 30-3 again to enter the second-stage glass bottle for bubbling to form gas with certain humidity, such as humidity saturation; the other path is mixed with the gas with saturated humidity through a second flow control valve 41-2 and a float flowmeter 42 to form carrier gas with specific humidity.

The source of feed gas (20) may be, for example, a relatively high concentration of a high pressure sample gas to be diluted, such as styrene, xylene, formaldehyde, and the like. The raw material gas is depressurized through the second pressure reducing valve 21. For example, the gas pressure in the high pressure gas cylinder may be reduced to a specified range according to the user's demand. And then flows to the mixing chamber 50 at a fixed flow rate by restricting the flow rate by the second flow meter 30-2. Where it is diluted and mixed with the carrier gas to thereby form a sample gas having a specific concentration and a specific humidity. To reduce or prevent adsorption of gases, the mixing chamber may be a passivated mixing chamber, such as a silanized glass mixing chamber or a 316L passivated mixing chamber.

The uniformly mixed moisture is divided into 2 paths, one path is emptied after the temperature and the humidity are measured by a hygrothermograph 60, and a float flowmeter 42-2 can be arranged in the flow path to indicate the flow; and the other path enters a sampling device or an analysis device.

In the dynamic dilution dispensing system for a gas standard substance according to the present invention, the connection line between the above-mentioned components may be a passivation line, for example, a silanized glass line or a 316L passivation line, thereby reducing or preventing adsorption of the sample gas.

Referring to fig. 1, the system for dynamically diluting and dispensing a gaseous standard substance according to the present invention may further include a heating device (70) (shown by a dotted line), wherein the humidifying device (40), the mixing chamber (50), and the thermo-hygrometer (60) are disposed in the heating device (70). For example, the heating device (70) may be integrally formed as a chamber, the humidifying device (40), the mixing chamber (50) and the hygrothermograph (60) are arranged in the chamber, and the heating device (70) may heat the chamber in various ways such as air bath heating, heating jacket and resistance wire heating, so that the humidifying device (40), the mixing chamber (50) and the hygrothermograph (60) therein maintain a predetermined temperature.

Accurate adjustment and calculation of the lower humidity at a specific temperature can be achieved by using the heating device (70), and the humidifying device and the mixing chamber (50) are arranged in the heating device (70), so that the problems of adsorption on the inner wall of the gas mixing pool, water condensation and the like can be reduced or prevented.

The system for dynamic dilution of a gaseous standard of the present invention further comprises a control module (not shown). For example, the opening and closing of the valve, the control of the gas flow, the temperature and the humidity, and the acquisition of corresponding data can be realized by control software. FIG. 2 is a schematic view of the control software operating interface of one embodiment of the present invention. As shown in reference 2. The set flow rate for each flow meter 30 can be set by directly entering the data in the corresponding window and clicking the "send" button. The temperature of heating can be set by inputting the target temperature in the column below the "PID temperature" and clicking the "send" key. When the flow and the fluctuation of the temperature and humidity of the gas need to be monitored for a long time, the sampling period (data acquisition frequency) and the sampling time can be set, the start key is clicked to acquire data, and the result of the data acquisition is updated in the upper right corner of the software interface in real time. When the data needs to be analyzed and processed, the collected data can be converted into a file which can be identified by excel software for analysis by using a data export function.

In addition, due to the adoption of the heating device (70), the passivation pipeline and the mixing chamber, the system can carry out a pre-purging step in a mode of 'system pressure closing-baking-emptying-purging', so that the system can be stabilized in a short time, and the utilization efficiency of the system is greatly improved.

The pre-purge step of the "system closed pressure-bake-vent-purge" mode of the system of the present invention is described in detail below with reference to the accompanying drawings.

Firstly, a, heating a humidifying device (40) and a mixing chamber (50) to a preset temperature by using a heating device (70);

b. closing the outlet of the mixing chamber (50), then opening the diluent gas source (10) such that the pressure in the diluent gas path rises to a predetermined pressure, for example slowly to, for example, about 10 atmospheres, and then closing the diluent gas source (10);

c. the outlet of the mixing chamber (50) is opened to vent the pressure,

d. repeating the steps b-c for a plurality of times, such as 3-5 times, so that the diluent gas path is filled with diluent gas, and then closing the diluent gas path;

e. closing the outlet of the mixing chamber (50), then opening the raw gas source (20) to slowly raise the pressure in the raw gas path to a predetermined pressure, for example, about 10 atmospheres, and then closing the raw gas source (20);

f. the outlet of the mixing chamber (50) is opened to vent the pressure,

g. and e, repeating the steps e-f for a plurality of times, such as 3-5 times, so that the raw material gas path is filled with the raw material gas.

Then, each flowmeter and each flow control valve 1-3 are opened, all the flow is set normally, and the system can quickly reach a stable state. The precise flow and temperature are then adjusted as needed to configure a standard gas with a particular humidity and concentration.

Due to the adoption of a passivation pipeline and a mixing chamber, and the combination of a cleaning mode of system closed pressure, baking, emptying and blowing for multiple cycles, the time for the system to reach stability can be greatly shortened.