Device and method for providing nitrogen pentoxide standard gas

Abstract

The present invention provides a device and method for providing nitrogen pentoxide standard gas, wherein the device comprises: a reaction gas reacts in a reaction unit to generate nitrogen pentoxide, wherein the reaction gas comprises nitrogen monoxide and ozone; a detection unit is used to detect the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit; and a calculation unit is used to obtain the concentration of nitrogen pentoxide. t1 , C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t2 , C t2 The regulating unit is used to regulate the volume of the reaction unit or the flow rate of the reaction gas, so that the residence time of the reaction gas in the reaction unit is time t2. The present invention has the advantages of automation and good stability.

Description

Technical Field

[0001] The invention relates to the generation of standard gas, and in particular to a device and method for providing nitrogen pentoxide standard gas. Background Art

[0002] Nitrate radicals (NO3) are important atmospheric oxidants at night in the ambient atmosphere. The product of the reaction between nitrate and nitrogen dioxide, dinitrogen pentoxide (N2O5), affects the formation of nitrate particles and the activation of chlorine radicals at night. Research on nitrate and dinitrogen pentoxide and the measurement of their environmental concentrations have become a research hotspot in the field of atmospheric chemistry in recent years. Since NO3 and N2O5 gases are unstable and difficult to preserve, there are currently no commercial calibration instruments on the market for the calibration of nitrate radicals and dinitrogen pentoxide. However, the N2O5 solid prepared in the laboratory is difficult to preserve (needs to be stored at -80°C), and the concentration of N2O5 gas produced by purging N2O5 solid with N2 is unstable. Summary of the invention

[0003] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides a device for providing nitrogen pentoxide standard gas.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A device for providing nitrogen pentoxide standard gas, the device for providing nitrogen pentoxide standard gas comprising:

[0006] A reaction unit, in which a reaction gas reacts to generate nitrogen pentoxide, wherein the reaction gas includes nitrogen monoxide and ozone;

[0007] A detection unit, the detection unit is used to detect the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit;

[0008] A calculation unit for obtaining the concentration of nitrogen pentoxide , C t1、 C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t2、 C t2 are the concentrations of the same gas respectively;

[0009] The regulating unit is used to regulate the volume of the reaction unit or the flow rate of the reaction gas so that the residence time of the reaction gas in the reaction unit is time t2.

[0010] Another object of the present invention is to provide a method for providing nitrogen pentoxide standard gas, which is achieved by the following technical solutions:

[0011] A method for providing nitrogen pentoxide standard gas, wherein the method for providing nitrogen pentoxide standard gas is:

[0012] The reaction gas reacts in the reaction unit to generate nitrogen pentoxide, wherein the reaction gas includes nitrogen monoxide and ozone;

[0013] Real-time detection of the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit;

[0014] The volume of the reaction unit or the flow rate of the reaction gas is adjusted so that the residence time of the reaction gas in the reaction unit is time t2, and time t2 satisfies the condition,

[0015] , C t1、 C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t2、 C t2 are the concentrations of the same gas respectively, and C1 is the concentration of the nitrogen pentoxide standard gas to be obtained.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] Nitrogen pentoxide is produced by on-site reaction, and the residence time of the reaction gas in the reaction unit is used to accurately adjust the concentration of nitrogen pentoxide, thereby achieving:

[0018] 1. Generate nitrogen pentoxide gas online, no need to prepare it in the laboratory and store it under dry ice conditions, simple and convenient;

[0019] 2. Detect the concentration of ozone (nitrogen dioxide) in real time, and make sure that when the residence time of the reaction gas in the reaction unit is t2, the concentration of nitrogen pentoxide in the reaction unit reaches the requirement;

[0020] By adjusting the volume of the reaction unit or the flow rate of the reaction gas, the residence time of the reaction gas in the reaction unit is adjusted, and the adjustment method is reliable and stable;

[0021] 3. The calculation unit uses the formula to accurately calculate the concentration of nitrogen pentoxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The disclosure of the present invention will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. In the drawings:

[0023] Figure 1 1 is a schematic structural diagram of a device for providing nitrogen pentoxide standard gas according to Example 1 of the present invention. DETAILED DESCRIPTION

[0024] Figure 1 The following description describes the optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to explain the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or replacements derived from these embodiments will be within the scope of the present invention. Those skilled in the art will understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following optional embodiments, but is only limited by the claims and their equivalents.

[0025] Example 1

[0026] Figure 1 The structural diagram of the device for providing nitrogen pentoxide standard gas according to the embodiment of the present invention is schematically shown as follows: Figure 1 As shown, the device for providing nitrogen pentoxide standard gas includes:

[0027] A reaction unit, in which a reaction gas reacts to generate nitrogen pentoxide, wherein the reaction gas includes nitrogen monoxide and ozone;

[0028] A detection unit, the detection unit is used to detect the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit;

[0029] A calculation unit for obtaining the concentration of nitrogen pentoxide , C t1、 C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t2、 C t2 are the concentrations of the same gas respectively;

[0030] The regulating unit is used to regulate the volume of the reaction unit or the flow rate of the reaction gas so that the residence time of the reaction gas in the reaction unit is time t2.

[0031] In order to accurately obtain the time t1, further, , C 01 is the initial concentration of ozone in the reaction unit, C 02 is the initial concentration of nitric oxide in the reaction unit, K is a coefficient, and η is the conversion ratio of nitric oxide to nitrogen dioxide in the reaction unit.

[0032] In order to accurately obtain the coefficient K, further, the coefficient K is the reaction rate constant of the following reaction:

[0033] NO+O3→NO2+O2.

[0034] In order to send the standard gas that meets the requirements to the downstream and discharge the standard gas that does not meet the requirements, the nitrogen pentoxide standard gas providing device further includes:

[0035] A switching module, the switching module is used to selectively connect the outlet of the reaction unit to different channels;

[0036] A gas source provides a reaction gas.

[0037] The method for providing nitrogen pentoxide standard gas according to the embodiment of the present invention is as follows:

[0038] The reaction gas reacts in the reaction unit to generate nitrogen pentoxide, wherein the reaction gas includes nitrogen monoxide and ozone;

[0039] Real-time detection of the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit;

[0040] The volume of the reaction unit or the flow rate of the reaction gas is adjusted so that the residence time of the reaction gas in the reaction unit is time t2, and time t2 satisfies the condition,

[0041] , C t1、 C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t2、 C t2 are the concentrations of the same gas respectively, C1 is the concentration of the nitrogen pentoxide standard gas to be obtained;

[0042] In order to accurately obtain the time t1, further, , C 01 is the initial concentration of ozone in the reaction unit, C 02 is the initial concentration of nitric oxide in the reaction unit, K is a coefficient, and η is the conversion ratio of nitric oxide to nitrogen dioxide in the reaction unit.

[0043] In order to accurately obtain the coefficient K, further, the coefficient K is the reaction rate constant of the following reaction:

[0044] NO+O3→NO2+O2.

[0045] In order to send the standard gas that meets the requirements to the downstream and discharge the standard gas that does not meet the requirements, the nitrogen pentoxide standard gas providing device further includes:

[0046] A switching module, the switching module is used to selectively connect the outlet of the reaction unit to different channels;

[0047] A gas source provides a reaction gas.

[0048] Example 2

[0049] An application example of the device and method for providing nitrogen pentoxide standard gas according to Example 1 of the present invention.

[0050] In this application example, among the gas sources, the first gas source adopts a steel cylinder to provide nitric oxide of known concentration; the second gas source adopts an ozone production unit, such as CN200910154006.3; the adjustment unit adopts a piston to adjust the volume of the reaction unit in real time; the detection unit adopts a spectrophotometer to detect the concentration of nitrogen dioxide in the mixed gas.

[0051] The method for providing nitrogen pentoxide standard gas according to the embodiment of the present invention is specifically as follows:

[0052] Nitric oxide of known concentration provided by the gas source reacts with excess ozone in the reaction unit to generate nitrogen pentoxide;

[0053] The detection unit detects the concentration of nitrogen dioxide in the mixed gas discharged from the reaction unit in real time;

[0054] The volume of the reaction unit is adjusted: the larger the volume, the longer the residence time, so that the residence time of the reaction gas in the reaction unit (residence time corresponds to the concentration of nitrogen pentoxide) is time t2, and time t2 meets the condition,

[0055] , C t1、 C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t2、 C t2 are the concentrations of the same gas respectively, C1 is the concentration of the nitrogen pentoxide standard gas to be obtained;

[0056] , C 01 is the initial concentration of ozone in the reaction unit, C 02 is the initial concentration of nitric oxide in the reaction unit, η is the conversion ratio of nitric oxide to nitrogen dioxide in the reaction unit, such as 90%, 95%, 99%; coefficient K is the reaction rate constant of the following reaction:

[0057] NO+O3→NO2+O2;

[0058] In the above process, if the concentration of nitrogen pentoxide discharged from the reaction unit does not meet the requirement, it is emptied by switching the module;

[0059] If the requirements are met, the nitrogen pentoxide standard gas is sent to the application equipment through the switching module.

[0060] Example 3

[0061] The application example of the device and method for providing nitrogen pentoxide standard gas according to Example 1 of the present invention is different from Example 2 in that:

[0062] 1. The detection unit detects the concentration of ozone;

[0063] 2. The regulating unit regulates the flow rate of the reaction gas so that the residence time of the reaction gas in the reaction unit is time t2: the greater the flow rate, the shorter the residence time;

[0064] 3. The mixed gas discharged from the reaction unit is diluted, thereby reducing the concentration of dinitrogen pentoxide. The dilution multiple is determined according to the dinitrogen pentoxide concentration output by the reaction unit and the dinitrogen pentoxide concentration required by the standard gas.

Claims

1. A device for providing nitrogen pentoxide standard gas, It is characterized in that The device for providing the nitrogen pentoxide standard gas comprises: A reaction unit, in which a reaction gas reacts to generate nitrogen pentoxide, wherein the reaction gas includes nitrogen monoxide and ozone; A detection unit, the detection unit is used to detect the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit; A calculation unit for obtaining the concentration of nitrogen pentoxide , C t1 , C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t1 , C t2 are the concentrations of the same gas respectively; A regulating unit, the regulating unit is used to adjust the volume of the reaction unit or the flow rate of the reaction gas so that the residence time of the reaction gas in the reaction unit is time t2; , C 01 is the initial concentration of ozone in the reaction unit, C 02 is the initial concentration of nitric oxide in the reaction unit, K is a coefficient, and η is the conversion ratio of nitric oxide to nitrogen dioxide in the reaction unit.

2. The device for providing nitrogen pentoxide standard gas according to claim 1, It is characterized in that The coefficient K is the reaction rate constant for the following reaction: NO+O 3 →NO 2 +O 2 。 3. The device for providing nitrogen pentoxide standard gas according to claim 1, It is characterized in that The device for providing the nitrogen pentoxide standard gas also includes: A switching module, the switching module is used to selectively connect the outlet of the reaction unit to different channels; A gas source provides a reaction gas.

4. A method for providing nitrogen pentoxide standard gas, wherein the method for providing nitrogen pentoxide standard gas is: The reaction gas reacts in the reaction unit to generate nitrogen pentoxide, wherein the reaction gas includes nitrogen monoxide and ozone; Real-time detection of the concentration of ozone or nitrogen dioxide in the mixed gas discharged from the reaction unit; The volume of the reaction unit or the flow rate of the reaction gas is adjusted so that the residence time of the reaction gas in the reaction unit is time t2, and time t2 satisfies the condition, , C t1 , C t2 are the concentrations of ozone or nitrogen dioxide when the reaction gas enters the reaction unit at time t1 and t2, respectively, C t1 , C t2 are the concentrations of the same gas, C 1 is the concentration of nitrogen pentoxide standard gas to be obtained; , C 01 is the initial concentration of ozone in the reaction unit, C 02 is the initial concentration of nitric oxide in the reaction unit, K is a coefficient, and η is the conversion ratio of nitric oxide to nitrogen dioxide in the reaction unit.

5. The method for providing nitrogen pentoxide standard gas according to claim 4, It is characterized in that The coefficient K is the reaction rate constant for the following reaction: NO+O 3 →NO 2 +O 2 。 6. The method for providing nitrogen pentoxide standard gas according to claim 4, It is characterized in that By switching, when the residence time of the reaction gas in the reaction unit does not reach time t2, it is emptied.

7. The method for providing nitrogen pentoxide standard gas according to claim 4, It is characterized in that In the reaction within the reaction unit, ozone is in excess.

Images