Standard gas preparation system and method based on optical cavity ring-down spectroscopy detection technology

Abstract

The application relates to a standard gas preparation system and method based on a cavity ring-down spectroscopy detection technology, characterized in that the standard gas preparation system comprises a high-precision standard gas preparation host, a gas supply unit, a flow control unit, a gas mixing unit, a cavity ring-down spectroscopy in-situ online detection unit and an adjusting output unit; a microcomputer of the high-precision standard gas preparation host is used for controlling normal operation of each unit in the system. The above-mentioned standard gas preparation system can measure the concentration of standard substances in-situ under a high-pressure environment, is representative, can generate standard gas with any given concentration by monitoring and feeding back in real time and controlling the in-out of gas in a high-pressure gas cabin according to the feedback, is more flexible and applicable, and since the method does not need to use high-accuracy gas which is expensive as a source standard gas, the production cost of the standard gas is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of standard gas preparation, in particular to a standard gas preparation system and method based on optical cavity ring-down spectroscopy detection technology. BACKGROUND

[0002] The standard gas preparation method mainly has static gas preparation method and dynamic gas preparation method, wherein the static gas preparation method is generally divided into two categories: one is weighing method, the mass of the substance is calculated according to the molecular weight and the concentration to be prepared, and the mass of each component is weighed by using an ultra-high precision balance to obtain a mixed standard gas; the other is volume method, according to the gas equation, a plurality of gases are mixed according to the calculated volume and then pressurized, and then filled into a high-pressure cylinder.

[0003] Among them, when the standard gas prepared by using the static gas preparation method, the precision of the weighing method and the volume method is not high, and the uncertainty is usually more than 1%. When using the dynamic gas preparation method, the standard gas prepared by using the static gas preparation method needs to be used as a reference, and the uncertainty is higher. In the prior art, in order to improve the preparation precision of the dynamic gas preparation method, a high-accuracy gas is usually used as a reference, and the price of the high-accuracy gas such as primary standard gas is dozens of times of that of ordinary standard gas, that is, the manufacturing cost will be greatly increased.

[0004] In addition, since the precision of the traditional standard gas preparation method is not high, the standard gas preparation can only produce standard gas near the target concentration, and cannot obtain standard gas of any given concentration, and in order to accurately calibrate the concentration of the standard gas, a high-precision laser ring-down spectroscopy device is usually used to measure the accurate value, and finally the concentration is given. However, the high-precision laser ring-down spectroscopy device is not pressure-resistant, and if it is used to measure the concentration, the prepared standard gas needs to be first depressurized, and then measured after depressurization. Due to the gas stratification in the high-pressure cylinder (for example, the gas concentration of the front 2MPa and the rear 2MPa is different from that of the middle layer in the case of 15MPa standard gas), the gas concentration measured by the high-precision laser ring-down spectroscopy device after depressurization is not enough to completely represent the whole bottle of standard gas, that is, the above method is not representative enough.

[0005] Therefore, it is urgent to design a standard gas preparation system and method based on optical cavity ring-down spectroscopy detection technology to solve the problems existing in the prior art. SUMMARY

[0006] Therefore, the present application provides a standard gas preparation system and method based on optical cavity ring-down spectroscopy detection technology, which aims to improve the precision of the prepared standard gas by designing a detection device with pressure resistance to detect the gas in the high-pressure gas cabin of the prepared standard gas in real time.

[0007] To achieve the above purpose, the present application adopts the following technical solutions:

[0008] A standard gas preparation system based on optical cavity ring-down spectroscopy detection technology, characterized in that the standard gas preparation system comprises a high-precision standard gas preparation host, a gas supply unit, a flow control unit, a gas mixing unit, an optical cavity ring-down spectroscopy in-situ online detection unit, and an adjustment and output unit; the microcomputer of the high-precision standard gas preparation host is used to control the normal operation of each unit in the system;

[0009] The gas supply unit comprises at least two source standard gas supply bottles with different concentrations and one dilution gas supply bottle;

[0010] The flow control unit is used to control the different gases in the gas supply unit to enter the gas mixing unit;

[0011] The gas mixing unit is provided with a high-pressure gas cabin;

[0012] The optical cavity ring-down spectroscopy in-situ online detection unit is used to measure the concentration and gas pressure of the mixed gas in the high-pressure gas cabin in real time; the optical cavity ring-down spectroscopy in-situ online detection unit comprises a pressure-bearing structure and a pressure-resistant optical fiber penetrating piece, the pressure-bearing structure is arranged in the high-pressure gas cabin of the gas mixing unit, the pressure-resistant optical fiber penetrating piece is arranged on the wall of the high-pressure gas cabin, and the pressure-bearing structure is connected with other components of the optical cavity ring-down spectroscopy in-situ online detection unit through the pressure-resistant optical fiber penetrating piece;

[0013] The adjustment and output unit is used to output the mixed gas in the high-pressure gas cabin.

[0014] Further, a pressure reducing valve is arranged at the outlet of each gas supply bottle in the gas supply unit, which is used to reduce the pressure of the high-pressure gas in the gas supply bottle; the source standard gas supply bottles are two, and the concentrations of the first source standard gas and the second source standard gas differ by one order of magnitude; the gas in the dilution gas supply bottle is an inert gas;

[0015] A plurality of mass flow controllers are arranged in the flow control unit, the number of the mass flow controllers is equal to the number of the gas supply bottles in the gas supply unit, and the mass flow controllers correspond to the gas supply bottles one by one;

[0016] The adjustment and output unit comprises one mass flow controller and one electromagnetic valve; the mass flow controller in the adjustment and output unit is used to control the outflow amount of the mixed gas in the high-pressure gas cabin; and the electromagnetic valve is used to control whether the mixed gas in the high-pressure gas cabin flows out.

[0017] Further, the optical cavity ring-down spectroscopy in-situ online detection unit further comprises a laser, an isolator, an acousto-optic modulator, a detector, and a control circuit;

[0018] The laser, isolator, acousto-optic modulator, detector, and control circuit are all housed within the casing of the high-precision standard gas preparation host.

[0019] The laser is connected in sequence to an isolator and an acousto-optic modulator via optical fiber, and then to a pressure-bearing structure located in a high-pressure gas chamber via a pressure-resistant optical fiber penetrating component. The pressure-bearing structure is then connected to a detector located in the housing of a high-precision standard gas preparation host via an optical fiber penetrating component.

[0020] The control circuit is used to control the normal operation of other components in the in-situ online detection unit of the optical cavity ring-down spectrum, and is also connected to the microcomputer of the high-precision standard gas preparation host.

[0021] Furthermore, the in-situ online detection unit for cavity ring-down spectroscopy also includes a pressure gauge, which is installed in the high-pressure gas chamber of the gas mixing unit. The pressure gauge is used to measure the gas pressure in the high-pressure gas chamber and transmit the information to the microcomputer of the high-precision standard gas preparation host via an electrical signal.

[0022] Furthermore, the pressure-bearing structure includes a shell, a pair of reflectors, a aligner, a pair of adapters, a pair of reflector fixing parts, an air inlet, and an air outlet, with each component within the pressure-bearing structure arranged symmetrically.

[0023] The outer casing includes a tubular shell and mounting joints welded to both ends of the tubular shell;

[0024] The reflector is fixedly installed inside the reflector fixing component; the reflector fixing component is fixedly connected to the mounting joint at the end of the tubular housing;

[0025] The collimator is fixedly installed inside the adapter fixture, and the adapter fixture is fixedly connected to the mounting joint;

[0026] The tubular housing, collimator, reflector, adapter fixture, and reflector fixing component are all coaxially arranged.

[0027] The air inlet and outlet are located on the outer wall of the tubular shell, near the two ends of the tubular shell 7-3-1, respectively, to allow gas to enter and exit the pressure-bearing structure.

[0028] Furthermore, the collimator is provided with an optical fiber plug in the middle for connecting optical fibers.

[0029] Furthermore, the main material of the tubular shell is Invar steel, the reflectivity of the high-reflectivity mirror is 99.98%, and the distance L between the two high-reflectivity mirrors is 230mm.

[0030] The present invention also provides a method for preparing a standard gas based on the above-described standard gas preparation system, characterized in that the method for preparing the standard gas includes:

[0031] S1. The target concentration and gas pressure of the standard gas to be prepared are set by the high-precision standard gas preparation host, and the high-precision standard gas preparation host calculates the required mass flow and gas partial pressure of each source standard gas and dilution gas;

[0032] S2. The high-precision standard gas preparation host sends a signal to the flow control unit according to the calculation result, and each mass flow controller in the flow control unit controls each source standard gas and dilution gas to enter the high-pressure gas cabin as required for mixing;

[0033] S3. The optical cavity ring-down spectroscopy in-situ online detection unit measures the concentration and gas pressure of the mixed gas in the high-pressure gas cabin in real time, and feeds back the measurement result to the high-precision standard gas preparation host;

[0034] S4. The high-precision standard gas preparation host compares the real-time measurement result with the target concentration and gas pressure; according to the comparison data, each mass flow controller of the flow control unit is further used to control each source standard gas or dilution gas to enter the high-pressure gas cabin as required for mixing, until the measured result matches the target concentration and gas pressure;

[0035] S5. The prepared standard gas in the high-pressure gas cabin is output through the output unit.

[0036] Further, the step S3 is specifically as follows:

[0037] The gas pressure in the high-pressure gas cabin is measured in real time by a pressure gauge arranged in the high-pressure gas cabin , and the pressure information is transmitted to the microcomputer of the high-precision standard gas preparation host through an electrical signal;

[0038] The output frequency of the laser is adjusted to make the laser send the peak frequency and baseline reference frequency of the target molecular characteristic absorption peak in turn, and the laser is transmitted to the pressure-bearing structure in the high-pressure gas cabin through the optical fiber, the isolator, the acousto-optic modulator and the pressure-resistant optical fiber penetration piece in turn, and the absorbed light signal is output to the detector for absorption analysis through the pressure-resistant optical fiber penetration piece, and the absorption height difference H at the two points is used to calculate the sample partial pressure, and the specific calculation formula of the target molecular partial pressure is as follows:

[0039] ;

[0040] In the formula, S(T) is the target molecular spectral line intensity, which is calculated from the parameters in the HITRAN database; is the Lorentz line function value of the target molecule at frequency v, which is directly calculated from the line function;

[0041] The target gas concentration X is calculated as follows:

[0042] .

[0043] Further, the step S4 further comprises:

[0044] According to the comparison data, the mixed gas in the high-pressure gas cabin is appropriately discharged by using the mass flow controller and the electromagnetic valve in the adjusting output unit, and each source standard gas or dilution gas is controlled to enter the high-pressure gas cabin for mixing by using the mass flow controller of the flow control unit respectively according to the requirement, until the measured result is consistent with the target concentration and gas pressure.

[0045] Compared with the prior art, the application has the beneficial effects that:

[0046] (1) The application solves the pressure resistance and miniaturization problems of high-sensitivity laser cavity ring-down spectroscopy by designing a light cavity ring-down spectroscopy in-situ online detection unit with a pressure-bearing structure and a pressure-resistant optical fiber penetrating piece, putting the pressure-bearing structure into a high-pressure gas cabin, and connecting the pressure-resistant optical fiber penetrating piece with other components in a normal pressure environment. The gas concentration in a high-pressure environment can be detected with high precision in-situ and online without pressure reduction, ensuring the accuracy of the high-pressure gas prepared by the static gas preparation method during the whole life cycle. In addition, the standard gas preparation system in the application can measure the concentration of standard substances in-situ under high pressure, which is representative.

[0047] (2) The standard gas preparation system in the application is combined with the dynamic gas preparation method, and the expensive high-accuracy gas as the source standard gas is not needed. The accuracy of the prepared standard gas is better than that of the standard gas prepared by using the primary standard gas as the source standard gas, which greatly reduces the production cost of the standard gas. The standard gas preparation method of the application can generate standard gas with any given concentration by real-time monitoring feedback and controlling the gas in and out of the high-pressure gas cabin, making the method more flexible and applicable.

[0048] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by means of the structures pointed out in the description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0050] Figure 1The structural schematic diagram of a standard gas preparation system based on the optical cavity ring-down spectroscopy detection technology is shown in the embodiment of the present application.

[0051] Figure 2 The structural schematic diagram of an in-situ online detection unit of the optical cavity ring-down spectroscopy is shown in the embodiment of the present application.

[0052] Figure 3 The three-dimensional structural schematic diagram of the pressure-bearing structure is shown in the embodiment of the present application.

[0053] Figure 4 The sectional view of the pressure-bearing structure is shown in the embodiment of the present application.

[0054] Figure 5 The first partial sectional view of the pressure-bearing structure is shown in the embodiment of the present application.

[0055] Figure 6 The second partial sectional view of the pressure-bearing structure is shown in the embodiment of the present application.

[0056] Figure 7 The sectional view of the collimator is shown in the embodiment of the present application.

[0057] In the figure: 1, high-precision standard gas preparation host; 2, mass flow controller; 3, pressure reducing valve; 4, source standard gas supply bottle; 5, dilution gas supply bottle; 6, high-pressure gas cabin; 7, pressure-bearing structure; 8, electromagnetic valve; 9, pressure-resistant optical fiber penetrating piece; 10, laser; 11, isolator; 12, acousto-optic modulator; 13, detector;

[0058] 7-1, adapter tool; 7-2, gas inlet; 7-3, shell; 7-4, gas outlet; 7-5, mirror; 7-6, collimator; 7-7, mirror fixing piece;

[0059] 7-3-1, tubular shell; 7-3-2, mounting joint. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0061] The present application provides a standard gas preparation system based on the optical cavity ring-down spectroscopy detection technology, as shown in the accompanying Figures 1-7As shown, the standard gas preparation system comprises a high-precision standard gas preparation host 1, a gas supply unit, a flow control unit, a gas mixing unit, a cavity ring-down spectroscopy in-situ online detection unit, and an adjustment and output unit; a microcomputer of the high-precision standard gas preparation host 1 is used to control normal operation of each unit in the system;

[0062] The gas supply unit comprises at least two source standard gas supply bottles 4 with different concentrations and one dilution gas supply bottle 5;

[0063] The flow control unit is used to control different gases in the gas supply unit to enter the gas mixing unit;

[0064] The gas mixing unit is provided with a high-pressure gas cabin 6;

[0065] The cavity ring-down spectroscopy in-situ online detection unit is used to measure the concentration and pressure of the mixed gas in the high-pressure gas cabin in real time; the cavity ring-down spectroscopy in-situ online detection unit comprises a pressure-bearing structure 7 and a pressure-resistant optical fiber penetrating piece 9, the pressure-bearing structure 7 is arranged in the high-pressure gas cabin 6 of the gas mixing unit, the pressure-resistant optical fiber penetrating piece 9 is arranged on the wall of the high-pressure gas cabin 6, and the pressure-bearing structure 7 is connected with other components of the cavity ring-down spectroscopy in-situ online detection unit through the pressure-resistant optical fiber penetrating piece 9;

[0066] The adjustment and output unit is used to output the mixed gas in the high-pressure gas cabin.

[0067] Each gas supply bottle outlet in the gas supply unit is provided with a pressure reducing valve 3 for reducing the pressure of the high-pressure gas in the gas supply bottle; the source standard gas supply bottles 4 are two, and the concentrations of the first source standard gas and the second source standard gas differ by one order of magnitude; the gas in the dilution gas supply bottle 5 is an inert gas.

[0068] A plurality of mass flow controllers 2 are arranged in the flow control unit, the number of the mass flow controllers 2 is equal to the number of the gas supply bottles in the gas supply unit, and each mass flow controller 2 corresponds to one gas supply bottle.

[0069] The adjustment and output unit comprises one mass flow controller 2 and one electromagnetic valve 8; the mass flow controller 2 in the adjustment and output unit is used to control the outflow of the mixed gas in the high-pressure gas cabin 6; and the electromagnetic valve 8 is used to control whether the mixed gas in the high-pressure gas cabin 6 flows out.

[0070] The cavity ring-down spectroscopy in-situ online detection unit further comprises a laser 10, an isolator 11, an acousto-optic modulator 12, a detector 13, and a control circuit;

[0071] The laser 10, the isolator 11, the acousto-optic modulator 12, the detector 13, and the control circuit are arranged in the shell of the high-precision standard gas preparation host 1;

[0072] The laser 10 is connected in sequence through a fiber connection isolator 11, an acousto-optic modulator 12, and a pressure-resistant optical fiber penetration piece 9 to a pressure-bearing structure 7 located in a high-pressure gas cabin, which is connected through an optical fiber penetration piece 9 to a detector 13 located in the shell of the high-precision standard gas preparation host 1.

[0073] The control circuit is used to control the normal operation of other components in the optical cavity ring-down spectroscopy in-situ online detection unit, and is connected with the microcomputer of the high-precision standard gas preparation host 1.

[0074] The optical cavity ring-down spectroscopy in-situ online detection unit further comprises a pressure gauge arranged in the high-pressure gas cabin 6 of the gas mixing unit, which is used to measure the gas pressure in the high-pressure gas cabin 6 and transmit information to the microcomputer of the high-precision standard gas preparation host 1 through an electrical signal.

[0075] The pressure-bearing structure comprises a shell 7-3, a pair of mirrors 7-5, a pair of collimators 7-6, a pair of adapter tooling 7-1, a pair of mirror fixing pieces 7-7, an air inlet 7-2 and an air outlet 7-4, and the components in the pressure-bearing structure are symmetrically arranged;

[0076] The shell 7-3 comprises a tubular shell 7-3-1 and mounting joints 7-3-2 welded at both ends of the tubular shell 7-3-1;

[0077] The mirror 7-5 is fixedly installed in the mirror fixing piece 7-7, and the mirror fixing piece 7-7 is fixedly connected in the mounting joint 7-3-2 at the end of the tubular shell 7-3-1;

[0078] The collimator 7-6 is fixedly installed in the adapter tooling 7-1, and the adapter tooling 7-1 is fixedly connected to the mounting joint 7-3-2;

[0079] The tubular shell 7-3-1, the collimator 7-6, the mirror 7-5, the adapter tooling 7-1 and the mirror fixing piece 7-7 are coaxially arranged;

[0080] The air inlet 7-2 and the air outlet 7-4 are arranged on the outer wall of the tubular shell 7-3-1, respectively near both ends of the tubular shell 7-3-1, for allowing gas to enter and flow out of the pressure-bearing structure.

[0081] The middle part of the collimator 7-6 is provided with an optical fiber plug for connecting an optical fiber; before the optical fiber is inserted into the optical fiber plug, AB glue is coated in the optical fiber plug, and after the optical fiber is inserted into the optical fiber plug, the AB glue can ensure that the optical fiber is more stably connected to the pressure-bearing structure.

[0082] The main material of the tubular shell 7-3-1 is invar, the reflectivity of the high reflector is 99.98%, and the distance L between the two high reflectors is 230 mm.

[0083] The application further provides a standard gas preparation method of a standard gas preparation system based on the optical cavity ring-down spectroscopy detection technology.

[0084] S1. The target concentration and gas pressure of the standard gas to be prepared are set by the high-precision standard gas preparation host, and the mass flow and gas partial pressure of each source standard gas and dilution gas required are calculated by the high-precision standard gas preparation host;

[0085] S2. The high-precision standard gas preparation host sends a signal to the flow control unit according to the calculation result, and each mass flow controller in the flow control unit controls each source standard gas and dilution gas to enter the high-pressure gas cabin for mixing according to the requirement;

[0086] S3. The optical cavity ring-down spectroscopy in-situ online detection unit measures the concentration and gas pressure of the mixed gas in the high-pressure gas cabin in real time, and feeds back the measurement result to the high-precision standard gas preparation host;

[0087] S4. The high-precision standard gas preparation host compares the real-time measurement result with the target concentration and gas pressure; according to the comparison data, each mass flow controller of the flow control unit is further used to control each source standard gas or dilution gas to enter the high-pressure gas cabin for mixing according to the requirement, until the measurement result matches the target concentration and gas pressure;

[0088] S5. The prepared standard gas in the high-pressure gas cabin is output through the output unit.

[0089] The step S3 is specifically as follows:

[0090] The gas pressure in the high-pressure gas cabin 6 is measured in real time by a pressure gauge arranged in the high-pressure gas cabin 6 , and the pressure information is transmitted to the microcomputer of the high-precision standard gas preparation host 1 through an electric signal;

[0091] The output frequency of the laser 10 is adjusted, so that the laser 10 sends laser of the peak frequency and the baseline reference frequency of the target molecular characteristic absorption peak in turn, enters the isolator 11 and the acousto-optic modulator 12 through the optical fiber in turn, and is transmitted to the pressure-bearing structure 7 in the high-pressure gas cabin 6 through the pressure-resistant optical fiber penetration piece 9, and the absorbed light signal is output to the detector 13 for absorption analysis through the pressure-resistant optical fiber penetration piece 9, and the absorption height difference H at the two points is used to calculate the sample partial pressure, and the specific calculation formula of the target molecular partial pressure is as follows:

[0092] ;

[0093] S (T) is the target molecule spectral line intensity, which is calculated from the parameters in the HITRAN database; L (v) is the target molecule Lorentz line shape function value at frequency v, which is directly calculated from the line shape function;

[0094] The target gas concentration X is specifically calculated as follows:

[0095] .

[0096] The step S4 further comprises:

[0097] According to the comparison data, the mixed gas in the high-pressure gas cabin is appropriately discharged by using the mass flow controllers and electromagnetic valves in the adjusting output unit, and each source standard gas or dilution gas is controlled to enter the high-pressure gas cabin for mixing according to the requirements by using the mass flow controllers of the flow control unit, until the measured result is consistent with the target concentration and gas pressure.

[0098] The application solves the pressure resistance and miniaturization problems of high-sensitivity laser cavity ring-down spectroscopy by designing an in-situ online detection unit of optical cavity ring-down spectroscopy with a pressure-bearing structure and a pressure-resistant optical fiber penetrating member, putting the pressure-bearing structure into the high-pressure gas cabin, and connecting the pressure-resistant optical fiber penetrating member with other components in a normal pressure environment. The gas concentration in the high-pressure environment can be detected with high precision in-situ and online without pressure reduction, ensuring the accuracy of the high-pressure gas prepared by the static gas preparation method during the whole life cycle. Moreover, the standard gas preparation system in the application can measure the concentration of standard substances in-situ under high pressure, which is representative.

[0099] The standard gas preparation system in the application is combined with the dynamic gas preparation method, without using high-accuracy gas as the source standard gas (the price of high-accuracy gas such as primary standard gas is dozens of times that of ordinary standard gas), and the accuracy of the prepared standard gas is better than that of the standard gas prepared by using primary standard gas as the source standard gas, which greatly reduces the production cost of standard gas. Moreover, the standard gas preparation method of the application can generate standard gas with any given concentration by real-time monitoring feedback and controlling the gas in and out of the high-pressure gas cabin, making the method more flexible and applicable.

[0100] Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A standard gas preparation system based on optical cavity ring-down spectroscopy detection technology, characterized in that, The standard gas preparation system comprises a high-precision standard gas preparation host (1), a gas supply unit, a flow control unit, a gas mixing unit, a cavity ring-down spectroscopy in-situ online detection unit, and an adjustment and output unit; the microcomputer of the high-precision standard gas preparation host (1) is used to control the normal operation of each unit in the system; The gas supply unit comprises at least two source standard gas supply bottles (4) with different concentrations and one dilution gas supply bottle (5); The flow control unit is used to control the different gases in the gas supply unit to enter the gas mixing unit; The gas mixing unit is provided with a high-pressure gas cabin (6); The cavity ring-down spectroscopy in-situ online detection unit is used to measure the concentration and pressure of the mixed gas in the high-pressure gas cabin in real time; the cavity ring-down spectroscopy in-situ online detection unit comprises a pressure-bearing structure (7) and a pressure-resistant optical fiber penetrating piece (9), the pressure-bearing structure (7) is arranged in the high-pressure gas cabin (6) of the gas mixing unit, the pressure-resistant optical fiber penetrating piece (9) is arranged on the wall of the high-pressure gas cabin (6), and the pressure-bearing structure (7) is connected with other components of the cavity ring-down spectroscopy in-situ online detection unit through the pressure-resistant optical fiber penetrating piece (9); The adjustment and output unit is used to output the mixed gas in the high-pressure gas cabin.

2. The standard gas preparation system based on optical cavity ring-down spectroscopy detection technology according to claim 1, wherein, Each gas supply bottle outlet in the gas supply unit is provided with a pressure reducing valve (3) for reducing the pressure of the high-pressure gas in the gas supply bottle; the source standard gas supply bottles (4) are two, and the concentrations of the first source standard gas and the second source standard gas differ by one order of magnitude; the gas in the dilution gas supply bottle (5) is an inert gas; A plurality of mass flow controllers (2) are arranged in the flow control unit, the number of the mass flow controllers (2) is equal to the number of the gas supply bottles in the gas supply unit, and each mass flow controller corresponds to one gas supply bottle; The adjustment and output unit comprises one mass flow controller (2) and one electromagnetic valve (8); the mass flow controller (2) in the adjustment and output unit is used to control the outflow amount of the mixed gas in the high-pressure gas cabin (6); and the electromagnetic valve (8) is used to control whether the mixed gas in the high-pressure gas cabin (6) flows out.

3. The standard gas preparation system based on optical cavity ring-down spectroscopy detection technology according to claim 1, wherein, The cavity ring-down spectroscopy in-situ online detection unit further comprises a laser (10), an isolator (11), an acousto-optic modulator (12), a detector (13), and a control circuit; The laser (10), the isolator (11), the acousto-optic modulator (12), the detector (13), and the control circuit are arranged in the shell of the high-precision standard gas preparation host (1); The laser (10) is sequentially connected with the isolator (11), the acousto-optic modulator (12) through an optical fiber, and is connected with the pressure-bearing structure (7) in the high-pressure gas cabin through the pressure-resistant optical fiber penetrating piece (9); the pressure-bearing structure (7) is connected with the detector (13) in the shell of the high-precision standard gas preparation host (1) through the optical fiber penetrating piece (9); The control circuit is used to control the normal operation of other components in the cavity ring-down spectroscopy in-situ online detection unit, and is connected with the microcomputer of the high-precision standard gas preparation host (1).

4. The standard gas preparation system based on optical cavity ring-down spectroscopy detection technology according to claim 3, characterized in that, The optical cavity ring-down spectroscopy in-situ online detection unit further comprises a pressure gauge arranged in the high-pressure gas chamber (6) of the gas mixing unit, which is used to measure the gas pressure in the high-pressure gas chamber (6) and transmit information to the microcomputer of the high-precision standard gas preparation host (1) through an electrical signal.

5. The standard gas preparation system based on optical cavity ring-down spectroscopy detection technology according to claim 4, characterized in that, The pressure-bearing structure comprises an outer shell (7-3), a pair of reflecting mirrors (7-5), a pair of collimators (7-6), a pair of adapter toolings (7-1), a pair of reflecting mirror fixing members (7-7), a gas inlet (7-2) and a gas outlet (7-4), and the components in the pressure-bearing structure are symmetrically arranged; The outer shell (7-3) comprises a tubular shell (7-3-1) and mounting joints (7-3-2) welded at both ends of the tubular shell (7-3-1); The reflecting mirrors (7-5) are fixedly installed in the reflecting mirror fixing members (7-7); the reflecting mirror fixing members (7-7) are fixedly connected in the mounting joints (7-3-2) at the ends of the tubular shell (7-3-1); The collimators (7-6) are fixedly installed in the adapter toolings (7-1), and the adapter toolings (7-1) are fixedly connected to the mounting joints (7-3-2); The tubular shell (7-3-1), the collimators (7-6), the reflecting mirrors (7-5), the adapter toolings (7-1) and the reflecting mirror fixing members (7-7) are coaxially arranged; The gas inlet (7-2) and the gas outlet (7-4) are arranged on the outer wall of the tubular shell (7-3-1) and are respectively close to both ends of the tubular shell (7-3-1) for allowing the gas to enter and flow out of the pressure-bearing structure.

6. The standard gas preparation system based on optical cavity ring-down spectroscopy detection technology according to claim 5, wherein, An optical fiber plug is arranged in the middle of the collimator (7-6) for connecting an optical fiber.

7. The standard gas preparation system based on optical cavity ring-down spectroscopy detection technology according to claim 5, wherein, The main material of the tubular shell (7-3-1) is invar steel, the reflectivity of the high-reflectivity mirror is 99.98%, and the distance between the two high-reflectivity mirrors is 230 mm.

8. A standard gas preparation method of a standard gas preparation system based on the optical cavity ring-down spectroscopy detection technology according to any one of claims 1-7, characterized in that, The standard gas preparation method comprises: S1. The target concentration and gas pressure of the standard gas to be prepared are set by the high-precision standard gas preparation host, and the required mass flow and gas partial pressure of each source standard gas and dilution gas are calculated by the high-precision standard gas preparation host; S2. The high-precision standard gas preparation host sends signals to the flow control unit according to the calculation results, and each mass flow controller in the flow control unit controls each source standard gas and dilution gas to enter the high-pressure gas chamber as required for mixing; S3. The optical cavity ring-down spectroscopy in-situ online detection unit measures the concentration and gas pressure of the mixed gas in the high-pressure gas chamber in real time and feeds back the measurement results to the high-precision standard gas preparation host; S4. The high-precision standard gas preparation host compares the real-time measurement results with the target concentration and gas pressure; according to the comparison data, each mass flow controller of the flow control unit is further used to control each source standard gas or dilution gas to enter the high-pressure gas chamber as required for mixing until the measurement results match the target concentration and gas pressure; S5. The prepared standard gas in the high-pressure gas chamber is output by adjusting the output unit.

9. The standard gas preparation method according to claim 8, wherein The step S3 is specifically as follows: The gas pressure in the high-pressure gas cabin (6) is measured in real time by a pressure gauge arranged in the high-pressure gas cabin (6) and the pressure information is transmitted to the microcomputer of the high-precision standard gas preparation host (1) through an electric signal; By regulating the output frequency of the laser (10), the laser (10) sends laser of peak frequency of target molecule characteristic absorption peak and baseline reference frequency in turn, enters the isolator (11) and the acousto-optic modulator (12) in turn through the optical fiber, and is transmitted to the pressure-bearing structure (7) in the high-pressure gas cabin (6) through the pressure-resistant optical fiber penetration piece (9), and the absorbed light signal is output to the detector (13) for absorption analysis through the pressure-resistant optical fiber penetration piece (9), and the absorption height difference H at the two points is used for calculating the sample partial pressure, and the specific calculation formula of the target molecule partial pressure is as follows: ； In the formula, S(T) is the target molecule spectral line intensity, which is calculated from the parameters in the HITRAN database; is the Lorentz line shape function value of the target molecule at frequency v, which is directly calculated from the line shape function. The target gas concentration X is calculated as follows: 。 10. The standard gas preparation method according to claim 8, wherein The step S4 further includes: According to the comparison data, the mixed gas in the high-pressure gas cabin is appropriately discharged by using the mass flow controller and the electromagnetic valve in the adjusting output unit, and each source standard gas or dilution gas is controlled to enter the high-pressure gas cabin for mixing according to the demand by using each mass flow controller of the flow control unit, until the measured result is consistent with the target concentration and the gas pressure.

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