Method for rapidly determining oxygen and argon in mixed gas

Abstract

The invention discloses a method for rapidly determining oxygen and argon in mixed gas. The method comprises the following steps: firstly, determining and calculating an oxygen correction factor and an argon correction factor through a gas chromatography thermal conductivity detector taking hydrogen as carrier gas; determining and calculating an oxygen correction factor and an argon correction factor through a gas chromatography thermal conductivity detector taking nitrogen as carrier gas; enabling the mixed gas to pass through a gas chromatography thermal conductivity detector taking hydrogen as carrier gas to determine the sum of response peak areas of oxygen and argon; enabling the mixed gas to pass through a gas chromatography thermal conductivity detector taking nitrogen as carrier gas to determine the sum of response peak areas of oxygen and argon; and finally calculating the content of oxygen and argon in the mixed gas. The method is simple to operate, efficient and accurate in measurement result.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis technology, and more specifically to a gas chromatography method for determining the content of oxygen and argon in a mixed gas without separating oxygen and argon. Background Technology

[0002] GB / T28124—2011 Determination of Trace Hydrogen, Oxygen, Methane and Carbon Monoxide in Inert Gases by Gas Chromatography recommends using a gas chromatograph equipped with a cobalt oxide detector when measuring the oxygen content in inert gases.

[0003] In coal chemical processes, gas chromatographs equipped with thermal conductivity detectors (TCD) are typically used to detect gases such as crude coal gas, shift gas, purified gas, and ammonia synthesis inlet and outlet gases. However, this configuration cannot separate oxygen and argon. Summary of the Invention

[0004] The purpose of this invention is to detect the content of oxygen and argon without separating them using a gas chromatograph equipped with a thermal conductivity detector (TCD).

[0005] Method Principle: The TCD detector, or thermal conductivity detector, is a general-purpose detector in gas chromatography. Its quantification is based on the linear relationship between the peak area and the concentration of a component. , For component content, The peak area of ​​the component. This is the component peak correction factor. When two components cannot be separated and their chromatographic peaks overlap into a single chromatographic peak, the peak area is equal to the sum of the peak areas of the two components, i.e. = If the thermal conductivity of the two gases is different, then according to the principle of peak area summation, chromatographic analysis can be performed using two different gases as carrier gases respectively, resulting in: = (1), = (2), Solving the system of equations (1) and (2) simultaneously yields: (3), (4).

[0006] If component 1 and component 2 are oxygen and argon respectively, the contents of oxygen and argon can be determined under non-separation conditions using the method described above.

[0007] The gas chromatography method of the present invention for determining the oxygen and argon content in a mixed gas without separation includes the following steps:

[0008] S1. The oxygen correction factor was determined and calculated using a gas chromatograph with hydrogen as the carrier gas and a thermal conductivity detector. Argon correction factor ;

[0009] S2. The oxygen correction factor was determined and calculated using a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector. Argon correction factor ;

[0010] S3. The sum of the response peak areas of oxygen and argon is determined by passing the gas mixture to be tested through a gas chromatography-thermal conductivity detector with hydrogen as the carrier gas. ;

[0011] S4. The sum of the response peak areas of oxygen and argon is determined by passing the gas mixture to be tested through a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector. ;

[0012] S5. Calculate the oxygen content in the gas mixture. ;

[0013] S6. Calculate the argon content in the gas mixture. ;

[0014] Furthermore, the gas mixture to be tested may contain components whose retention time does not overlap with that of oxygen and argon.

[0015] Further, the method for determining the correction factor in step S1 is as follows: oxygen and argon standard substances of known concentrations are passed into a gas chromatograph with hydrogen as the carrier gas thermal conductivity detector, respectively, to obtain the oxygen response peak area and the argon response peak area. The ratio of the oxygen concentration or argon concentration in the standard substance to the corresponding gas response peak area is the correction factor. The oxygen correction factor was obtained when hydrogen was used as the carrier gas. Argon correction factor ;

[0016] Further, the method for determining the correction factor in step S2 is as follows: Oxygen and argon standard substances of known concentrations are passed into a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector, respectively, to obtain the oxygen response peak area and the argon response peak area. The ratio of the oxygen concentration or argon concentration in the standard substance to the corresponding gas response peak area is the correction factor. The oxygen correction factor was obtained when nitrogen was used as the carrier gas. Argon correction factor ;

[0017] Furthermore, oxygen standard material and argon standard material, with the gas to be tested or the gas not to be tested as the base gas, are respectively introduced into the gas chromatograph thermal conductivity detector.

[0018] Furthermore, the gas mixture to be tested may contain components whose retention time does not overlap with that of oxygen and argon.

[0019] Furthermore, the concentration of each component in the gas mixture to be tested is arbitrary.

[0020] Furthermore, the oxygen concentration of the oxygen standard in the mixed gas is arbitrary, and the argon concentration of the argon standard in the mixed gas is arbitrary.

[0021] Furthermore, the concentrations of oxygen and argon in the gas mixture to be tested are arbitrary.

[0022] The present invention has the following advantages:

[0023] This invention utilizes a gas chromatograph with a thermal conductivity detector, commonly used in coal chemical chemical analysis, to detect the content of oxygen and argon in cases where they cannot be separated. This method is simple to operate, efficient, and provides accurate measurement results. Attached Figure Description

[0024] Figure 1 The chromatogram of oxygen standard material with hydrogen as carrier gas;

[0025] Figure 2 The chromatogram of an oxygen standard using nitrogen as the carrier gas is shown.

[0026] Figure 3 The chromatogram of argon standard material with hydrogen as carrier gas;

[0027] Figure 4 This is a chromatogram of an argon standard using hydrogen as the carrier gas. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments. The scope of protection of the present invention is not limited to the following description:

[0029] Example 1: A gas chromatography method for determining the oxygen and argon content in a mixed gas without separation, comprising the following steps:

[0030] S1: The oxygen and argon standards in the mixed gas are passed separately into a gas chromatograph with hydrogen as the carrier gas and a thermal conductivity detector. The peak areas of the oxygen and argon responses when hydrogen is used as the carrier gas are obtained. The ratio of the oxygen or argon concentration in the mixed gas standard to the corresponding gas response peak area is used as a correction factor. The oxygen correction factor was obtained when hydrogen was used as the carrier gas. Argon correction factor The oxygen concentration of the oxygen standard substance in the mixed gas is arbitrary, and the argon concentration of the argon standard substance is arbitrary.

[0031] S2: The oxygen and argon standards in the mixed gas are passed separately into a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector. The peak areas of the oxygen and argon responses when nitrogen is used as the carrier gas are obtained. The ratio of the oxygen or argon concentration in the mixed gas standard to the corresponding gas response peak area is used as a correction factor. The oxygen correction factor was obtained when hydrogen was used as the carrier gas. Argon correction factor The oxygen concentration of the oxygen standard substance in the mixed gas is arbitrary, and the argon concentration of the argon standard substance is arbitrary.

[0032] S3: Pass the gas mixture to be tested into a gas chromatograph with hydrogen as the carrier gas and obtain the sum of the response peak areas of oxygen and argon when hydrogen is used as the carrier gas. .

[0033] S4: Pass the gas mixture to be tested into a gas chromatograph with nitrogen as the carrier gas and obtain the sum of the response peak areas of oxygen and argon when nitrogen is used as the carrier gas. .

[0034] S5. Calculate the oxygen content in the gas mixture. ;

[0035] S6. Calculate the argon content in the gas mixture. ;

[0036] The following experiments illustrate the beneficial effects of this invention:

[0037] The experiment was conducted using a mixture of oxygen and argon as an example, with both oxygen and argon concentrations around 50%. The experimental method was the same for other gas concentrations.

[0038] Purchased oxygen and argon were used as standard substances, with oxygen purity ≥99.99% and argon purity ≥99.99%. The two standard substances were passed into gas chromatography thermal conductivity detectors using hydrogen as the carrier gas and nitrogen as the carrier gas, respectively, and measured three times. Correction factors were calculated according to the method of this invention. The experimental data for the correction factors of oxygen and argon are shown in Table 1.

[0039] Table 1: Experimental data on the determination of correction factors for oxygen and argon

[0040] The peak spectrum of oxygen in a gas chromatogram using a hydrogen carrier gas thermal conductivity detector is shown below. Figure 1 As shown; the peak spectrum of oxygen in a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector is as follows. Figure 2 As shown; the peak spectrum of argon gas eluted by a gas chromatograph with hydrogen as the carrier gas and a thermal conductivity detector is as follows. Figure 3As shown; the peak spectrum of argon gas eluted by a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector is as follows. Figure 4 As shown.

[0041] The actual sample was a mixture of oxygen and argon, prepared by mixing purchased oxygen and argon at a volume ratio of 1:1, with an oxygen concentration of 50% and an argon concentration of 50%. The oxygen and argon concentrations in the actual sample were measured using the method of this invention, and the results are shown in Tables 2 and 3. The relative deviations between the method of this invention and the theoretical nominal values ​​were 1.38% and 1.04%, respectively, demonstrating the accuracy and reliability of the method.

[0042] Table 2 Experimental data on the determination of oxygen and argon in actual samples

[0043]

[0044] Table 3 Calculation results of oxygen and argon concentrations in actual samples

[0045]

[0046] As shown in Tables 2 and 3, the relative deviation between the oxygen concentration obtained by the method of the present invention and the theoretical value is 1.38%, and the relative deviation between the argon concentration and the theoretical value is 1.04%, indicating that the error is small.

[0047] This invention can meet the needs of some enterprises equipped with gas chromatographs using thermal conductivity detectors for the determination of oxygen and argon content, eliminating the need for a separate gas chromatograph with a cobalt oxide detector, thus saving costs. This invention can be applied to the analysis of oxygen and argon content in oxygen-argon mixtures of various concentrations.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments without departing from the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for rapidly determining oxygen and argon in a mixed gas, characterized in that, It includes the following steps: S1. The oxygen correction factor was determined and calculated using a gas chromatograph with hydrogen as the carrier gas and a thermal conductivity detector. Argon correction factor ; S2. The oxygen correction factor was determined and calculated using a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector. Argon correction factor ; S3. The sum of the response peak areas of oxygen and argon was determined by passing the mixed gas through a gas chromatography-thermal conductivity detector using hydrogen as the carrier gas. ; S4. The sum of the response peak areas of oxygen and argon was determined by passing the mixed gas through a gas chromatograph with nitrogen as the carrier gas and measuring its intensity. ; S5. Calculate the oxygen content in the gas mixture. ; S6. Calculate the argon content in the gas mixture. .

2. The method for rapidly determining oxygen and argon in a mixed gas according to claim 1, characterized in that, The mixed gas contains components such as hydrogen, nitrogen, carbon monoxide, and carbon dioxide.

3. The method for rapidly determining oxygen and argon in a mixed gas according to claim 1, characterized in that, The method for calculating the correction factor in step S1 is as follows: Oxygen and argon standard substances of known concentrations are passed into a gas chromatograph with hydrogen as the carrier gas and a thermal conductivity detector, respectively. The peak areas of the oxygen and argon responses are obtained. The ratio of the oxygen or argon concentration in the standard substance to the corresponding gas response peak area is the correction factor. Oxygen correction factors were obtained respectively. Argon correction factor .

4. The method for rapidly determining oxygen and argon in a mixed gas according to claim 1, characterized in that, The method for calculating the correction factor in step S2 is as follows: Oxygen and argon standard substances of known concentrations are passed into a gas chromatograph with nitrogen as the carrier gas and a thermal conductivity detector, respectively. The peak areas of the oxygen and argon responses are obtained. The ratio of the oxygen or argon concentration in the standard substance to the corresponding gas response peak area is the correction factor. Oxygen correction factors were obtained respectively. Argon correction factor .

5. A method for rapidly determining oxygen and argon in a mixed gas according to any one of claims 3-4, characterized in that, Oxygen and argon standard substances, which are either the analyte or a non-analyte mixture, are introduced into the gas chromatograph thermal conductivity detector.

6. The method for rapidly determining oxygen and argon in a mixed gas according to claim 5, characterized in that, The non-tested mixed gas contains components such as hydrogen, nitrogen, carbon monoxide, and carbon dioxide.

7. A method for rapidly determining oxygen and argon in a mixed gas according to any one of claims 3-4, characterized in that, The concentrations of each component in the mixed gas, such as hydrogen, nitrogen, carbon monoxide, and carbon dioxide, are arbitrary.

8. A method for rapidly determining oxygen and argon in a mixed gas according to any one of claims 3-4, characterized in that, The oxygen concentration of the oxygen standard in the mixed gas is arbitrary, and the argon concentration of the argon standard in the mixed gas is arbitrary.

9. A method for rapidly determining oxygen and argon in a mixed gas according to any one of claims 3-4, characterized in that, The concentrations of oxygen and argon in the mixed gas are arbitrary.

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