CN114733380B - Standard gas generating device - Google Patents

Abstract

The invention discloses a standard gas generating device which comprises a dilution gas source, a mass flow controller, a dilution gas preheating pipeline, a sample standard liquid injection pump, an injector, a gas mixing cavity, a cavity heating module and a gas detector. The flow rate, namely the dilution factor, of the dilution gas source is controlled by a mass flow controller, and the dilution gas source is mixed with the sample standard liquid injected by the injector after passing through a preheating pipeline and is fully mixed in a heated gas mixing cavity, so that standard gas with certain concentration is obtained. The device provided by the invention can prepare single-component or multi-component standard gas with certain concentration, fully utilizes a limited space to uniformly mix the gas, and has important significance for preparing the standard gas with high uniformity, stable performance and accurate concentration.

Description

A standard gas generating device

Technical field

The invention belongs to the technical field of gas preparation, and specifically relates to a standard gas generating device.

Background technique

Standard gas is a standard material. It is a measurement standard with high uniformity, stable performance and accurate value. It is used to calibrate measuring instruments and measurement processes in the fields of physics, chemistry, biology and engineering, and to evaluate the detection capabilities and measurement methods of testing laboratories. The accuracy is of great significance. Commonly used standard gas preparation techniques generally include permeation method and liquid sample gasification dilution method. The disadvantage of the standard gas generation device based on permeation tubes is that one permeation tube can only correspond to one substance and cannot prepare mixed standard gases; for uncommon substances, customized permeation tubes are required, which is expensive. In addition, permeation tubes are powerless against substances that are solid at room temperature. The focus of the liquid sample vaporization dilution method is the gas mixing chamber, such as a baffle. The diluent gas and the sample gas are mixed through the baffle to obtain a standard gas of a certain concentration. However, the baffles and the cavity have edges and corners, which create dead volumes and make the gas concentration inaccurate. In addition, the existing liquid sample vaporization device still lacks the gas mixing volume in a certain space, making the standard gas not uniform enough.

Contents of the invention

The present invention proposes a standard gas generating device to solve the problems that the existing device based on permeation tubes cannot prepare mixed standard gases, and the gas prepared by the liquid sample gasification device is inaccurate and uneven.

In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

A standard gas generating device, which is connected with a diluent gas source, a mass flow controller, a gas mixing chamber and a gas detector through pipelines from left to right; between the mass flow controller and the gas mixing chamber The connecting pipe is the diluent gas preheating pipe;

The device also includes a syringe and a sample standard solution syringe pump; the syringe and the sample standard solution syringe pump are located below the gas mixing chamber, and the syringe is installed on the sample standard solution syringe pump;

The bottom of the gas mixing chamber is also provided with a cavity heating module for heating the gas mixing chamber; the gas mixing chamber is a cylinder, and there is a cylindrical cavity a, Cylindrical cavity b, cylindrical cavity c and cylindrical cavity d are used to increase the gas mixing volume so that the gas is fully mixed without dead volume; the cylindrical cavity a and cylindrical cavity b, cylinder A pipeline is connected between the top of the cylindrical cavity c and the cylindrical cavity d, and a pipeline is connected between the bottom of the cylindrical cavity b and the cylindrical cavity c; the inlet of the cylindrical cavity a The gas port is connected to the gas outlet of the diluent gas preheating pipeline, the gas outlet of the cylindrical cavity d is connected to the sampling port of the gas detector; the bottom gas inlet of the cylindrical cavity a, the cylindrical cavity The air outlets at the bottom of cavity d are respectively connected with the cavity heating module;

The outer wall of the dilution gas preheating pipeline is covered with a heating tape or heating cloth to achieve gas preheating;

The diluent gas source controls the flow rate, that is, the dilution factor, through a mass flow controller. After the diluent gas preheats the pipeline, it is mixed with the sample standard liquid injected by the syringe, and is fully mixed in the heated gas mixing chamber to obtain the standard gas. Enter the gas detector detection.

In the above technical solution, further, the diluent gas source is generally an inert gas nitrogen, argon or helium.

In the above technical solution, further, the pump speed of the sample standard liquid syringe pump can be adjusted to control the concentration of the required standard gas by controlling the amount of sample standard liquid entering the gas mixing chamber per unit time.

In the above technical solution, further, the inside of the syringe can be filled with a pure solvent or a single solution or a mixed solution, which can be one component or multiple components.

In the above technical solution, further, the gas detector may be a mass spectrometer or a gas chromatograph.

In the above technical solution, further, the flow rate of the sample standard solution syringe pump is 0-200mL/min, and the flow rate controlled by the mass flow controller is 0-30L/min.

In the above technical solution, further, the heating temperature of the cavity heating module is room temperature-500°C, and the preheating temperature of the diluent gas preheating pipeline is room temperature-500°C.

Preferably, the cylindrical cavity has no corners inside, and the cylindrical cavity a, the cylindrical cavity b, the cylindrical cavity c and the cylindrical cavity d are evenly distributed.

Compared with the existing technology, the beneficial effects of the present invention are:

The device provided by the invention can prepare single-component or multi-component standard gases of a certain concentration, make full use of the limited space to mix the gases evenly, and is of great significance to the preparation of standard gases with high uniformity, stable performance and accurate concentration.

Description of drawings

Figure 1 is a standard gas generating device of the present invention.

In the figure, 1. Diluent gas source; 2. Mass flow controller; 3. Diluent gas preheating pipeline; 4. Sample standard solution syringe pump; 5. Injector; 6. Gas mixing chamber; 7. Chamber heating module ; 8. Gas detector.

In the figure, 6-1. Cylindrical cavity a; 6-2. Cylindrical cavity b; 6-3 cylindrical cavity c; 6-4 cylindrical cavity d.

Detailed ways

The treatment process of the present invention will be further described below with reference to specific examples.

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

It should be noted that the terms used herein are for the purpose of describing specific embodiments only, and are not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular forms are also intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, it will be understood that when the terms "comprises" and/or "includes" are used in this specification, they indicate There are features, steps, operations, means, components and/or combinations thereof.

The relative arrangement of components and steps, numerical expressions, and numerical values set forth in these examples do not limit the scope of the invention unless specifically stated otherwise. At the same time, it should be understood that, for convenience of description, the dimensions of various parts shown in the drawings are not drawn according to actual proportional relationships. Techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and equipment should be considered part of the authorized specification. In all examples shown and discussed herein, any specific values are to be interpreted as illustrative only and not as limitations. Accordingly, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters refer to similar items in the following figures, so that once an item is defined in one figure, it does not need further discussion in subsequent figures.

In the description of the present invention, it should be understood that the orientation indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, vertical, horizontal" and "top, bottom" etc. Or the positional relationship is usually based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description. Without explanation to the contrary, these directional words do not indicate and imply the referred devices or components. Must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be construed as limiting the scope of the invention: the orientation words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

Example 1

As shown in Figure 1, a standard gas generating device is connected with a diluent gas source 1, a mass flow controller 2, a gas mixing chamber 6 and a gas detector 8 through pipelines from left to right. The device also includes a syringe 5 and a sample standard solution syringe pump 4; the connecting pipeline between the mass flow controller 2 and the gas mixing chamber 6 is the diluent gas preheating pipeline 3; the syringe 5 and the sample standard solution syringe pump 4 are located in the gas mixing chamber. Below the cavity 6, the syringe 5 is installed on the standard liquid injection pump 4;

The bottom of the gas mixing chamber 6 is also provided with a chamber heating module 7 for heating the gas mixing chamber 6. The heating temperature of the chamber heating module 7 is room temperature -500°C; the gas mixing chamber 6 is a cylinder, and the gas mixing chamber 6 There are evenly distributed cylindrical cavity a 6-1, cylindrical cavity b 6-2, cylindrical cavity c 6-3 and cylindrical cavity d 6-4 between the upper and lower bottom surfaces. Use To increase the gas mixing volume so that the gas is fully mixed without dead volume;

Pipes are connected between the tops of the cylindrical cavity a and the cylindrical cavity b, the cylindrical cavity c and the cylindrical cavity d, and the pipes are connected between the bottoms of the cylindrical cavity b and the cylindrical cavity c. path; the air inlet of the cylindrical cavity a is connected to the air outlet of the diluent gas preheating pipeline 3, and the air outlet of the cylindrical cavity d is connected to the sampling port of the gas detector 8; the cylindrical cavity a The bottom air inlet and the bottom air outlet of the cylindrical cavity d are connected with the cavity heating module 7 respectively.

The outer wall of the diluent gas preheating pipeline 3 is covered with a heating tape or heating cloth to achieve gas preheating. The diluent gas source 1 is generally inert gas nitrogen, argon or helium. The diluent gas source 1 controls the flow rate, that is, the dilution factor, through the mass flow controller 2. After the diluent gas preheats the pipeline 3, it is connected to the sample injected by the syringe 5. The standard liquid is mixed and thoroughly mixed in the heated gas mixing chamber 6, and the obtained standard gas enters the gas detector 8 for detection.

The pump speed of the sample standard liquid syringe pump 4 can be adjusted. By controlling the amount of sample standard liquid entering the gas mixing chamber 6 per unit time, the concentration of the required standard gas can be controlled. The flow rate of the sample standard liquid syringe pump 4 is 0-200mL/ min, pure solvent or single solution or mixed solution, can be one component or multiple components.

The gas detector 8 may be a mass spectrometer or a gas chromatograph. The flow rate controlled by the mass flow controller 2 is 0-30L/min, and the preheated temperature of the diluent gas preheating pipeline 3 is room temperature-500°C.

Further, as one embodiment, the diluent gas source 1 is nitrogen, and the mass flow controller 2 sets the flow rate to 2L/min.

Further, as one example, the pump speed of the sample standard solution syringe pump 4 is 20 μL/min.

Further, as one example, the syringe 5 is filled with a solution of paraxylene in carbon tetrachloride.

Further, as one embodiment, the heating temperature of the cavity heating module 7 is set to 160°C.

Further, as one embodiment, the gas detector 8 is a mass spectrometer.

The present invention prepares 100 ppbv paraxylene standard gas. The specific method is: use an analytical balance to weigh 0.3734g of pure paraxylene in a beaker, dissolve the carbon tetrachloride solvent and transfer it to a 25mL volumetric flask a (mother liquor); Use a pipette to pipette the solution in 500 μL volumetric flask a, and adjust the carbon tetrachloride solvent to 25mL volumetric flask b (the mother solution is diluted 50 times); use a pipette to pipette the solution in 2500 μL volumetric flask b, and use carbon tetrachloride solvent to Dilute the solvent to 25mL volumetric flask c (the mother liquor is diluted 500 times). Use syringe 5 to take the liquid in 1mL volumetric flask c, fix it on the sample standard solution syringe pump 4, and set the pump speed to 20 μL/min.

Note: The molar mass of paraxylene is 106.165g/mol; the boiling point of paraxylene is 138.5°C, and 160°C can ensure complete gasification of paraxylene; the gas molar volume at 160°C is 35.54L/mol.

Then the concentration of paraxylene standard gas prepared by the method of the present invention is:

Detected by photoionization time-of-flight mass spectrometry, the peak area is 24442;

The 100 ppbv paraxylene standard gas prepared in the gas library of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, was tested with the same instrument parameters of the same photoionization time-of-flight mass spectrometer, and the peak area was 24280.

Compared with the paraxylene standard gas prepared in the gas library, the error of the paraxylene standard gas prepared in the present invention is:

The error is only 0.67%, which illustrates the accuracy of the standard gas prepared by the present invention.

The technical principles of the present invention are described above in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present invention and should not be construed as limiting the scope of the present invention in any way. Based on the explanations here, those skilled in the art can think of other specific embodiments of the present invention without exerting creative efforts, and these equivalent modifications or substitutions are included in the scope defined by the claims of this application.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. scope.

Claims (7)

1. A standard gas generating device, characterized in that: the device is connected to a diluent gas source (1), a mass flow controller (2), a gas mixing chamber (6) and a gas through pipelines from left to right. Detector (8); the connecting pipeline between the mass flow controller (2) and the gas mixing chamber (6) is the diluent gas preheating pipeline (3); The device also includes a syringe (5) and a sample standard solution syringe pump (4); the syringe (5) and the sample standard solution syringe pump (4) are located below the gas mixing chamber, and the syringe (5) is installed on the sample. Standard solution syringe pump (4); The bottom of the gas mixing chamber is also provided with a cavity heating module for heating the gas mixing chamber; the gas mixing chamber is a cylinder, and there is a cylindrical cavity a ( 6-1), cylindrical cavity b (6-2), cylindrical cavity c (6-3) and cylindrical cavity d (6-4), used to increase the gas mixing volume and fully mix the gas And there is no dead volume; there are no corners inside the cylindrical cavity, cylindrical cavity a (6-1), cylindrical cavity b (6-2), cylindrical cavity c (6-3) and cylindrical cavity The cavities d (6-4) are evenly distributed; pipelines are connected between the tops of the cylindrical cavity a and the cylindrical cavity b, the cylindrical cavity c and the cylindrical cavity d. A pipeline is connected between the bottom of the cavity b and the cylindrical cavity c, and the air inlet of the cylindrical cavity a is connected with the air outlet of the diluent gas preheating pipeline (3); the cylindrical cavity d The gas outlet is connected to the inlet of the gas detector (8); the bottom gas inlet of the cylindrical cavity a and the bottom gas outlet of the cylindrical cavity d are respectively connected with the cavity heating module (7); The outer wall of the dilution gas preheating pipeline is covered with a heating tape or heating cloth to achieve gas preheating; The diluent gas source (1) controls the flow rate, that is, the dilution factor, through the mass flow controller (2). After passing through the diluent gas preheating pipeline (3), it is mixed with the sample standard solution injected by the syringe (5), and heated The gas mixing chamber (6) is fully mixed, and the obtained standard gas enters the gas detector (8) for detection. 2. The standard gas generating device according to claim 1, characterized in that the diluent gas source (1) is one of nitrogen and argon. 3. The standard gas generating device according to claim 1, characterized in that: the pump speed of the sample standard liquid injection pump (4) can be adjusted by controlling the sample standard liquid entering the gas mixing chamber (6) per unit time. quantity to control the concentration of the required standard gas. 4. The standard gas generating device according to claim 1, characterized in that the syringe (5) can be filled with pure solvent or a single solution or a mixed solution. 5. The standard gas generating device according to claim 1, characterized in that the gas detector (8) can be a mass spectrometer or a gas chromatograph. 6. The standard gas generating device according to claim 1, characterized in that: the flow rate of the sample standard solution injection pump (4) is 0-200 mL/min, and the flow rate controlled by the mass flow controller (2) is 0-30 L/min. 7. The standard gas generating device according to claim 1, characterized in that: the heating temperature of the cavity heating module (7) is room temperature-500°C, and the preheating temperature of the diluent gas preheating pipeline (3) is Room temperature -500℃.