Gas source switching system for high-precision gas absorption measurement

Abstract

The utility model discloses a gas source switching system for high-precision gas absorption measurement, which comprises a sampling valve group, a gas source switching device and a gas source switching device, the measuring pipeline comprises an air pump and an optical resonant cavity which are connected together, and the air outlet end of the measuring pipeline is communicated with the atmosphere; the air pressure balancing pipeline comprises a one-way valve, and the air outlet end of the air pressure balancing pipeline communicates with the atmosphere; and three valve ports of the three-way valve are respectively connected with the sampling valve group, the measuring pipeline and the air pressure balancing pipeline. According to the utility model, on the premise that the working parameters of the air pump are not changed, the pressure of the gas entering the optical resonant cavity is not changed when the sampling valve group switches the switching valve. Through the arrangement of the one-way valve on the air pressure balancing pipeline, one-way communication between steel cylinder air and the atmosphere is achieved, it can be guaranteed that the air pressure in the cavity is consistent with the atmospheric pressure all the time, and the air pump can be prevented from reversely extracting the air entering the air pressure balancing pipeline.

Description

Technical Field

[0001] The utility model relates to the technical field of optical cavity ring-down spectroscopy, in particular to a gas source switching system for high-precision gas absorption measurement. Background Art

[0002] In the CRDS system, the light beam from the single-frequency laser diode enters the optical resonant cavity, and is reflected back and forth in the cavity under the action of the laser pulse to form an oscillation. According to the attenuation process of the laser pulse, the change in gas concentration in the cavity can be known when the reflectivity is known. In this process, changes in gas temperature and pressure will affect the absorption linearity of the gas. Usually, the pressure is relatively high at the moment the cylinder standard gas is turned on and output. How to balance the gas pressure to make it equal to the pressure in the atmosphere, and then enter the cavity for measurement, is the key to improving the measurement accuracy. At present, the conventional method is to install a pressure regulating valve, but in actual operation, each switch needs to accurately adjust the valve to the correct position. The operating conditions are relatively harsh, and a slight error will reduce the accuracy of the gas measurement. Utility Model Content

[0003] The purpose of the utility model is to provide a gas source switching system for high-precision gas absorption measurement to solve the problems raised in the above background technology.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] The utility model discloses a gas source switching system for high-precision gas absorption measurement, comprising:

[0006] An injection valve group having at least four switch valves;

[0007] A measuring pipeline, comprising an air pump and an optical resonant cavity connected together, wherein an air outlet end of the measuring pipeline is connected to the atmosphere;

[0008] A balanced air pressure pipeline, comprising a one-way valve, wherein the air outlet end of the balanced air pressure pipeline is connected to the atmosphere;

[0009] The three valve ports of the three-way valve are respectively connected to the injection valve group, the measuring pipeline and the balanced air pressure pipeline.

[0010] A further solution is that one of the four switch valves is connected to the gas to be tested, and the other switch valves are respectively connected to standard gases of different concentrations.

[0011] A further solution: the injection valve group is a solenoid valve.

[0012] A further solution: the measuring pipeline further includes a filtering mechanism arranged between the three-way valve and the optical resonant cavity.

[0013] A further solution: the filtering mechanism comprises a primary filter and a secondary filter connected in series.

[0014] A further solution: the measuring pipeline also includes a flow valve arranged between the optical resonant cavity and the air pump.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] The utility model realizes that the pressure of the gas entering the optical resonant cavity remains unchanged when the injection valve group switches the switch valve under the premise that the working parameters of the air pump remain unchanged. The one-way valve on the balanced air pressure pipeline is set to stabilize the air pressure fluctuation, which can not only ensure that the air pressure in the cavity is always consistent with the atmospheric pressure, but also prevent the air pump from reversely extracting the gas entering the balanced air pressure pipeline. The utility model has a simple and novel structure and stable operation. It can achieve the stability of the gas pressure in the optical resonant cavity without installing a pressure regulating valve, thereby ensuring the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the utility model;

[0018] In the figure: 1-injection valve group, 2-measuring pipeline, 21-air pump, 22-optical resonant cavity, 23-flow valve, 24-filtering mechanism, 241-primary filter, 242-secondary filter, 3-balanced air pressure pipeline, 31-check valve, 4-three-way valve. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] In the description of the present utility model, it should be noted that the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present utility model.

[0021] See also Figure 1 In this embodiment, a gas source switching system for high-precision gas absorption measurement includes an injection valve group 1, a measurement pipeline 2, a balanced air pressure pipeline 3 and a three-way valve 4, wherein:

[0022] The injection valve group 1 has four switch valves, which are respectively connected to the gas to be tested and three cylinder standard gases with different concentrations. The relationship curve between the concentration and the output voltage is established through the three different concentrations of standard gases, and then the concentration of the gas to be tested is reversed through the output voltage.

[0023] The measuring pipeline 2 includes an air pump 21 and an optical resonant cavity 22 connected together, and the air outlet end of the measuring pipeline 2 is connected to the atmosphere;

[0024] A balanced air pressure pipeline 3, comprising a one-way valve 31, wherein the air outlet end of the balanced air pressure pipeline 3 is connected to the atmosphere;

[0025] The three-way valve 4 has three valve ports connected to the injection valve group 1, the measuring pipeline 2 and the balanced air pressure pipeline 3 respectively.

[0026] The gas enters the measuring pipeline 2 through the three-way valve. The air pump 21 extracts the standard gas or the gas to be measured from the gas source and enters the optical resonant cavity 22. The gas molecules are excited by the laser in the optical resonant cavity 22 to generate photons. These photons form a laser beam after multiple reflections and gains in the cavity. The air pump 21 is conducive to providing stable, pure and controllable gas to the optical resonant cavity 22. The balanced air pressure pipeline 3 allows the gas from the injection valve group 1 to be discharged unidirectionally, balancing the air pressure fluctuations in the pipeline and ensuring that the pressure entering the optical resonant cavity 22 is always consistent with the atmospheric pressure. The setting of the one-way valve prevents the air pump 21 from reversely extracting the gas in the balanced air pressure pipeline 3.

[0027] Furthermore, the injection valve group 1 is a solenoid valve, and the four switch valves are in a normally closed state and are switched open through serial communication.

[0028] Furthermore, the measuring pipeline 2 also includes a filtering mechanism 24 disposed between the three-way valve 4 and the optical resonant cavity 22. The filtering mechanism 24 is a two-stage filtering device, which includes a 30 μm primary filter 241 and a 7 μm secondary filter 242, which is disposed at the front end of the optical resonant cavity 22 to filter fine particles in the gas to prevent contamination of the lens in the optical resonant cavity 22.

[0029] Furthermore, a flow valve 23 is provided at the rear end of the optical resonant cavity 22 to control the gas flow rate.

[0030] When the utility model is in operation, firstly, the switch valve connected to the standard gas 1 is switched on and opened, and the other switch valves are closed, so that the gas enters the optical resonant cavity 22, and its output voltage is recorded; then the switch valve connected to the standard gas 2 is switched on and opened, and the other switch valves are closed, so that the gas enters the optical resonant cavity 22, and its output voltage is recorded; then the switch valve connected to the standard gas 3 is switched on and opened, and the other switch valves are closed, so that the gas enters the optical resonant cavity 22, and its output voltage is recorded; through the relationship between the known concentrations of standard gas 1, standard gas 2, and standard gas 3 and the output voltage, a relationship curve is obtained. The switch valve connected to the gas to be measured is switched on and opened, and the other switch valves are closed, so that the gas enters the optical resonant cavity 22, and its output voltage is recorded, and the concentration value of the gas to be measured is inferred based on the output voltage. The one-way valve 31 is a normally open valve. When the gas enters the optical resonant cavity 22, part of it is output to the atmosphere through the one-way valve, thereby stabilizing the pressure fluctuation caused by switching the switch valves.

[0031] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0032] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent changes made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A gas source switching system for high-precision gas absorption measurement, characterized in that: include: An injection valve group (1) having at least four switch valves; A measuring pipeline (2), comprising an air pump (21) and an optical resonant cavity (22) connected together, wherein the air outlet end of the measuring pipeline (2) is connected to the atmosphere; A balanced air pressure pipeline (3), comprising a one-way valve (31), wherein the air outlet end of the balanced air pressure pipeline (3) is connected to the atmosphere; The three-way valve (4) has three valve ports connected to the injection valve group (1), the measuring pipeline (2) and the balanced air pressure pipeline (3) respectively.

2. The gas source switching system for high-precision gas absorption measurement according to claim 1, characterized in that: One of the four switch valves is connected to the gas to be tested, and the other switch valves are respectively connected to standard gases of different concentrations.

3. The gas source switching system for high-precision gas absorption measurement according to claim 1, characterized in that: The injection valve group (1) is a solenoid valve.

4. The gas source switching system for high-precision gas absorption measurement according to claim 1, characterized in that: The measuring pipeline (2) also includes a filtering mechanism (24) arranged between the three-way valve (4) and the optical resonant cavity (22).

5. The gas source switching system for high-precision gas absorption measurement according to claim 4, characterized in that: The filtering mechanism (24) comprises a primary filter (241) and a secondary filter (242) connected in series.

6. The gas source switching system for high-precision gas absorption measurement according to claim 1, characterized in that: The measuring pipeline (2) also includes a flow valve (23) arranged between the optical resonant cavity (22) and the air pump (21).

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