Method for detecting content of sulfur dioxide

Abstract

The invention provides a method for detecting the content of sulfur dioxide. The detection method comprises the following steps: S1, setting working conditions of a gas chromatograph; s2, diluting sulfur dioxide standard gas with known volume concentration; s3, detecting sulfur dioxide standard gases with different volume concentrations through a gas chromatograph, and establishing a calibration curve and a calibration equation through the sulfur dioxide standard gases and the gas chromatograph; s4, detecting the to-be-detected gas through the gas chromatograph to obtain the peak area of sulfur dioxide in the to-be-detected gas; s5, substituting the peak area of the sulfur dioxide in the to-be-detected gas into the calibration equation for calculation to obtain the volume concentration of the sulfur dioxide in the to-be-detected gas. Wherein the peak area is the maximum value of the response value at the retention time corresponding to sulfur dioxide; the volume concentration of sulfur dioxide in the gas to be detected is 10 <-6 > (V / V) level. The detection method has the advantages of high detection sensitivity, selectivity and stability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of trace gas detection, and in particular to a method for detecting sulfur dioxide content. Background Art

[0002] For coal chemical process and coal-to-liquid process, the sulfur recovery device will produce tail gas containing sulfur dioxide at the end of the process. With the continuous improvement of environmental protection requirements, the control of sulfur dioxide content in the above processes has become more and more stringent. Therefore, it is particularly important to accurately detect the content of sulfur dioxide. The sulfur dioxide content in the exhaust gas is extremely small. The common method for detecting the concentration of sulfur dioxide is gas chromatography. Gas chromatography detection is currently the most widely used detection instrument in the laboratory, with the most convenient detection method, high stability and the best analysis continuity. However, for sulfur dioxide detection, the TCD detector of gas chromatography is limited by its own detection and cannot detect trace concentrations of sulfur dioxide. At present, the use of gas chromatography detection is limited to the detection of sulfur dioxide gas with a high content, and there is no detection at the trace level. The operation of other detection methods is relatively cumbersome and inefficient. Therefore, in view of the above problems, it is urgent to develop a method for detecting trace sulfur dioxide. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for detecting sulfur dioxide content, so as to solve the problems of low accuracy and precision, complicated operation and low efficiency in the prior art methods for detecting trace sulfur dioxide content.

[0004] In order to achieve the above-mentioned object, according to one aspect of the present invention, a method for detecting sulfur dioxide content is provided, and the method comprises the following steps: step S1, setting the working conditions of a gas chromatograph: the temperature of the injection port is 120-140°C, the column temperature is 40-120°C, the temperature of the flame photometer is 195-205°C, and the flow ratio of the fuel gas to the auxiliary fuel gas is 45-55:70-80; step S2, selecting a sulfur dioxide standard gas with a known volume concentration for dilution to obtain sulfur dioxide standard gases with different volume concentrations; step S3, using a gas chromatograph to measure the sulfur dioxide standard gas; step S4, measuring the sulfur dioxide standard gas with a known volume concentration; step S5, measuring the sulfur dioxide standard gas with a known volume concentration; step S6, measuring the sulfur dioxide standard gas with a known volume concentration; step S7, measuring the sulfur dioxide standard gas with a known volume concentration; step S8, measuring the sulfur dioxide standard gas with a known volume concentration; step S9, measuring the sulfur dioxide standard gas with a known volume concentration; step S10, measuring the sulfur dioxide standard gas with a known volume concentration; step S11, measuring the sulfur dioxide standard gas with a known volume concentration; step S12, measuring the sulfur dioxide standard gas with a known volume concentration; step S13, measuring the sulfur dioxide standard gas with a known volume concentration; step S14, measuring the sulfur dioxide standard gas with a known volume concentration; step S15, measuring the sulfur dioxide standard gas with a known volume concentration; step S16, measuring the sulfur dioxide standard gas with a known volume concentration; step S17, measuring the sulfur dioxide standard gas with a known volume concentration; step S18, measuring the sulfur dioxide standard gas with a known volume concentration; step S19, measuring the sulfur dioxide standard gas with a known volume concentration; step S20, measuring the sulfur dioxide standard gas with a known volume concentration; step S19, measuring the sulfur dioxide standard gas with a known volume concentration; step S21 The sulfur dioxide standard gas with different volume concentrations is detected to obtain sulfur dioxide with different volume concentrations and its corresponding peak area, and a calibration curve and a calibration equation are established through the two. Step S4: the gas to be tested is detected by a gas chromatograph to obtain the peak area of ​​sulfur dioxide in the gas to be tested. Step S5: the peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation to obtain the volume concentration of sulfur dioxide in the gas to be tested; wherein the peak area is the maximum value of the response value at the corresponding retention time of sulfur dioxide; the volume concentration of sulfur dioxide in the gas to be tested is 10 -6 (V / V) level.

[0005] Furthermore, in the above step S3, the calibration equation is Area = BAmt 2 -CAmt+D, where Area is the peak area of ​​sulfur dioxide, Amt is the volume concentration of sulfur dioxide, and the unit of Amt is ×10 -6 (V / V), B is 447.384421~911.791699, C is 58.066049~125.41122, and D is 12.837398~26.9666235.

[0006] Further, in the above step S3 and the above step S4, the retention time of sulfur dioxide is independently 2.70 to 2.80 min; and / or the volume concentration of sulfur dioxide in the gas to be measured is 0.1 to 2.0×10 -6 (V / V).

[0007] Furthermore, in the above step S3, the chromatographic column of the gas chromatograph is subjected to adsorption saturation treatment before detection. The process of adsorption saturation treatment is to pass the sulfur dioxide standard gas into the gas chromatograph until the response value no longer increases, and after standing by for 8 to 10 hours, the sulfur dioxide standard gas with the same volume concentration is detected, and the response value no longer changes.

[0008] Furthermore, in the above step S1, the column temperature is programmed, and the process of programmed temperature increase includes: taking 40°C as the initial temperature and maintaining it for 1 to 1.5 minutes, then heating it to 120°C at a rate of 100 to 110°C / min and maintaining it for 2 to 3 minutes.

[0009] Furthermore, in the above step S1, in step S1, the working conditions of the gas chromatograph also include: the tail gas is nitrogen, and the flow rate of the tail gas is 50-60 mL / min; and / or, the carrier gas is hydrogen, and the flow rate of the carrier gas is 4-6 mL / min.

[0010] Further, the fuel gas is hydrogen, and the flow rate of the fuel gas is 45-50 mL / min; and / or, the supporting fuel gas is air, and the flow rate of the supporting fuel gas is 70-75 mL / min.

[0011] Furthermore, in the above step S1, the chromatographic column of the gas chromatograph is a GS-Gaspro gas chromatographic column; and / or, the inner diameter of the GS-Gaspro gas chromatographic column is 0.32 mm; and / or, the length of the GS-Gaspro gas chromatographic column is 30 m.

[0012] Furthermore, in the above step S1, the gas chromatograph includes an injection system, and the sampler of the injection system is sulfur passivated; and / or the injection system includes an online dilution system; and / or the injection system is in a split mode; and / or the split ratio of the injection system is 1:1 to 1.5:1; and / or the injection volume of the injection system is 1 mL.

[0013] Furthermore, in the above step S2, dilution is performed by an online dilution system; and / or the volume concentration of the sulfur dioxide standard gas is 10 to 20×10 -6 (V / V).

[0014] By applying the technical solution of the present invention, in the method for detecting the sulfur dioxide content provided by the present application, the gas to be tested does not need to be pretreated and can be directly detected by a gas chromatograph. Therefore, the detection method of the present invention is simple to operate and has high efficiency. Setting the conditions of the gas chromatograph within the above range is helpful to fully separate the sulfur dioxide from the other components in the sulfur dioxide standard gas or the gas to be tested, thereby helping to improve the precision and accuracy of sulfur dioxide detection. In step S2 and step S3, sulfur dioxide standard gas of different volume concentrations is detected by a gas chromatograph, and different volume concentrations of sulfur dioxide and their corresponding peak areas are obtained, and a calibration curve and a calibration equation are established. The peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation, and the volume concentration of sulfur dioxide in the gas to be tested can be simply and accurately calculated. According to the detection method of the present application, thanks to the control of the working conditions of the gas chromatograph and the precision and accuracy test results that can be achieved, the volume concentration of sulfur dioxide that can be detected by the detection method of the present application can reach 10 -6 Therefore, the method for detecting the sulfur dioxide content of the present invention has the advantages of high detection sensitivity, selectivity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 The schematic diagram of the structure of the gas chromatograph of the present application is shown;

[0017] Figure 2 The schematic diagram of the structure of the online dilution system of the gas chromatograph of the present application is shown.

[0018] The above drawings include the following reference numerals:

[0019] 1. Injection valve; 2. Injection port; 3. GS-Gaspro gas chromatograph column; 4. Flame photometer; 5. Sulfur dioxide standard gas inlet; 6. Dilution gas inlet; 7. Mixed gas outlet; 8. Sulfur dioxide standard gas storage bottle. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] As analyzed in the background technology of this application, the existing methods for detecting trace sulfur dioxide content have problems such as low accuracy and precision, cumbersome operation and low efficiency. In order to solve the above problems, this application provides a method for detecting sulfur dioxide content.

[0022] In a typical embodiment of the present application, a method for detecting sulfur dioxide content is provided, and the method comprises the following steps: step S1, setting the working conditions of the gas chromatograph: the temperature of the injection port is 120-140°C, the column temperature is 40-120°C, the temperature of the flame photometer is 195-205°C, and the flow ratio of the fuel gas to the auxiliary fuel gas is 45-55:70-80; step S2, selecting a sulfur dioxide standard gas with a known volume concentration for dilution to obtain a sulfur dioxide standard gas with different volume concentrations; step S3, using the gas chromatograph to dilute the sulfur dioxide standard gas; step S4, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with different volume concentrations; step S5, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S6, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S7, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S8, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S9, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S10, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S11, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S12, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S13, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S14, diluting the sulfur dioxide standard gas with a known volume concentration to obtain a sulfur dioxide standard gas with a known volume concentration; step S1 The sulfur dioxide standard gas with different volume concentrations is tested to obtain sulfur dioxide with different volume concentrations and its corresponding peak area, and a calibration curve and a calibration equation are established through the two. Step S4: the gas to be tested is tested by a gas chromatograph to obtain the peak area of ​​sulfur dioxide in the gas to be tested. Step S5: the peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation to obtain the volume concentration of sulfur dioxide in the gas to be tested; wherein the peak area is the maximum value of the response value at the corresponding retention time of sulfur dioxide; the volume concentration of sulfur dioxide in the gas to be tested is 10 -6 (V / V) level.

[0023] In the detection method of sulfur dioxide content provided by the present application, the gas to be tested does not need to be pretreated and can be directly detected by gas chromatograph. Therefore, the detection method of the present invention is simple to operate and has high efficiency. Setting the conditions of the gas chromatograph within the above range is helpful to fully separate sulfur dioxide from other components in the sulfur dioxide standard gas or the gas to be tested, thereby helping to improve the precision and accuracy of sulfur dioxide detection. In step S2 and step S3, sulfur dioxide standard gas of different volume concentrations is detected by gas chromatograph, and different volume concentrations of sulfur dioxide and their corresponding peak areas are obtained, and calibration curves and calibration equations are established. The peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation, and the volume concentration of sulfur dioxide in the gas to be tested can be simply and accurately calculated. According to the detection method of the present application, thanks to the control of the working conditions of the gas chromatograph and the precision and accuracy test results that can be achieved, the volume concentration of sulfur dioxide that can be detected by the detection method of the present application can reach 10 -6Therefore, the method for detecting the sulfur dioxide content of the present invention has the advantages of high detection sensitivity, selectivity and stability.

[0024] In one embodiment of the present application, in the above step S3, the calibration equation is Area = BAmt 2 -CAmt+D, where Area is the peak area of ​​sulfur dioxide, Amt is the volume concentration of sulfur dioxide, and the unit of Amt is ×10 -6 (V / V), B is 447.384421~911.791699, C is 58.066049~125.41122, and D is 12.837398~26.9666235.

[0025] By substituting the peak area of ​​sulfur dioxide in the test gas into the calibration equation, it is helpful to further accurately calculate the volume concentration of sulfur dioxide in the test gas. It can be seen that different calibration equations are obtained according to different setting conditions of the gas chromatograph, which can more easily and accurately determine the volume concentration of sulfur dioxide in the test gas.

[0026] In one embodiment of the present application, in the above step S3 and the above step S4, the retention time of sulfur dioxide is independently 2.70 to 2.80 min, and / or the volume concentration of sulfur dioxide in the gas to be measured is 0.1 to 2.0×10 -6 (V / V).

[0027] According to the test method of the present application, the retention time of sulfur dioxide can be within the above range, thereby greatly improving the accuracy of testing the volume concentration of sulfur dioxide. The test method of the present application can more accurately test the volume concentration of sulfur dioxide to 0.1-2.0×10 -6 (V / V) of the gas to be tested.

[0028] In one embodiment of the present application, in the above step S3, the chromatographic column of the gas chromatograph is subjected to adsorption saturation treatment before detection. The process of adsorption saturation treatment is to pass the sulfur dioxide standard gas into the gas chromatograph until the response value no longer increases, and after standing by for 8 to 10 hours, the sulfur dioxide standard gas with the same volume concentration is detected, and the response value no longer changes.

[0029] Preferably, the above-mentioned adsorption saturation treatment of sulfur dioxide standard gas helps to better adapt to the characteristics of sulfur dioxide and improve separation efficiency, thereby further optimizing the parameters of chromatographic analysis to achieve the best separation effect. In addition, after standing by for 8 to 10 hours, the final response value no longer changes, that is, adsorption saturation has been achieved.

[0030] In one embodiment of the present application, in the above step S1, the column temperature is programmed, and the process of programmed temperature increase includes: taking 40°C as the initial temperature and maintaining it for 1 to 1.5 minutes, then heating it to 120°C at a rate of 100 to 110°C / min and maintaining it for 2 to 3 minutes.

[0031] Setting the above-mentioned programmed temperature rising conditions within the above-mentioned range can help to further improve the separation efficiency of sulfur dioxide in the gas to be tested, thereby helping to further improve the precision and accuracy of the detection.

[0032] In one embodiment of the present application, in the above step S1, the working conditions of the gas chromatograph also include: the tail gas is nitrogen, and the flow rate of the tail gas is 50-60 mL / min; and / or, the carrier gas is hydrogen, and the flow rate of the carrier gas is 4-6 mL / min; the fuel gas is hydrogen, and the flow rate of the fuel gas is 45-50 mL / min; and / or, the supporting gas is air, and the flow rate of the supporting gas is 70-75 mL / min.

[0033] Setting the conditions of the gas chromatograph within the above range helps to fully separate the sulfur dioxide in the gas to be tested, thereby helping to improve the precision and accuracy of the detection.

[0034] In one embodiment of the present application, in the above step S1, the chromatographic column of the gas chromatograph is a GS-Gaspro gas chromatographic column; and / or, the inner diameter of the GS-Gaspro gas chromatographic column is 0.32 mm; and / or, the length of the GS-Gaspro gas chromatographic column is 30 m.

[0035] The chromatographic column of the gas chromatograph is preferably a GS-Gaspro gas chromatographic column, and the specifications of the GS-Gaspro gas chromatographic column are controlled within the above range, which helps to improve the separation efficiency of sulfur dioxide in the gas to be tested under the above-set working conditions of the gas chromatograph, thereby helping to further improve the precision and accuracy of the detection.

[0036] In one embodiment of the present application, in the above step S1, the gas chromatograph includes an injection system, and the sampler of the injection system is sulfur passivated; and / or the injection system includes an online dilution system; and / or the injection system is in a split mode, and / or the split ratio of the injection system is 1:1 to 1.5:1; and / or the injection volume of the injection system is 1.0 mL.

[0037] Preferably, the injection system is subjected to sulfur passivation treatment, which helps to reduce the adsorption of sulfur dioxide on the chromatographic column, thereby improving the accuracy and repeatability of the analysis. Preferably, the mode, injection volume and split ratio of the injection system are controlled within the above range, which helps to improve the sensitivity of sulfur dioxide analysis and the accuracy of quantitative analysis.

[0038] In one embodiment of the present application, in the above step S2, dilution is performed by an online dilution system; and / or the volume concentration of the sulfur dioxide standard gas is 10 to 20×10 -6 (V / V).

[0039] Diluting the sulfur dioxide standard gas in the above volume concentration range through an online dilution system helps to obtain sulfur dioxide of different volume concentrations, which helps to further obtain its corresponding peak area, and establish a calibration curve and calibration equation through the two.

[0040] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0041] Example 1

[0042] 1. Test gas and instrument

[0043] Sulfur dioxide standard gas: Use national secondary standard material or prepare according to GB / T 5274. The components of sulfur dioxide standard gas should be in a uniform gaseous state.

[0044] Gas to be tested: High purity nitrogen containing trace amounts of SO2.

[0045] The gas chromatograph comprises: a sampling system, a sampler of the sampling system: GB / T 6681, a sampler tinfoil bag which is passivated with sulfur or has no adsorption to sulfur; a detector: a flame photometric detector; a chromatographic column: a GS-Gaspro gas chromatographic column, 30m×0.32mm (id).

[0046] Carrier gas, fuel gas and diluent gas: hydrogen, with a purity not lower than that specified in GB / T 3436.2.

[0047] Supporting gas: Compressed air, in accordance with the provisions of GB / T 13277.

[0048] Tail gas: nitrogen, purity not lower than the requirement specified in GB / T 8979.

[0049] 2. Detection steps

[0050] The working conditions of the gas chromatograph were set as follows: the temperature of the injection port was 120°C, the injection system was in split mode, the injection volume was 1 mL, the split ratio was 1:1, the temperature of the flame photometric detector was 200°C, the flow rate of the fuel gas was 50 mL / min, the flow rate of the supporting gas was 75 mL / min, the flow rate of the tail gas was 50 mL / min, and the flow rate of the carrier gas was 5 mL / min; the column temperature was programmed, and the programmed temperature increase process included: starting at 40°C and maintaining for 1 min, then heating to 120°C at 100°C / min and maintaining for 2 min.

[0051] The chromatographic column of the gas chromatograph is subjected to adsorption saturation treatment. The process of adsorption saturation treatment is to pass sulfur dioxide standard gas into the gas chromatograph until the response value no longer increases. After standing by for 8 hours, the sulfur dioxide standard gas with the same volume concentration is detected. If the response value no longer changes, it means that it has been adsorbed saturated.

[0052] Choose 10×10 -6 The sulfur dioxide standard gas was diluted by the online dilution system to obtain a volume concentration of 0.1×10 -6 (V / V), 0.2×10 -6 (V / V), 0.5×10 -6 (V / V), 1×10 -6 (V / V) and 2×10 -6 (V / V) of sulfur dioxide standard gas.

[0053] The above sulfur dioxide standard gas with different volume concentrations was detected by gas chromatography, and the above sulfur dioxide with different volume concentrations and their corresponding peak areas were 10.396, 42.476, 207.290, 743.300 and 3374.100, respectively. The calibration curve and calibration equation were established by the two. The calibration equation is Area = 893.6060118Amt 2 -113.17645Amt+24.240633, where Area is the peak area of ​​sulfur dioxide, Amt is the volume concentration of sulfur dioxide, and the unit of Amt is 10 -6 V / V.

[0054] The gas to be tested is tested three times in parallel by means of a gas chromatograph to obtain the peak areas of sulfur dioxide in the gas to be tested respectively.

[0055] Substitute the peak area of ​​sulfur dioxide in the above-mentioned gas to be measured into the calibration equation for calculation, and obtain the volume concentration of sulfur dioxide in the gas to be measured.

[0056] The peak area obtained above is the maximum value of the response value at the corresponding retention time of sulfur dioxide, and the retention time of sulfur dioxide is 2.71 min.

[0057] Example 2

[0058] The difference from Example 1 is that the working conditions of the gas chromatograph are set as follows: the temperature of the injection port is 130°C, the injection system is in split mode, the injection volume is 1 mL, the split ratio is 1.2:1, the temperature of the flame photometric detector is 195°C, the flow rate of the fuel gas is 45 mL / min, the flow rate of the auxiliary fuel gas is 75 mL / min, the flow rate of the tail gas is 55 mL / min, and the flow rate of the carrier gas is 4 mL / min; the column temperature is programmed, and the process of programmed temperature rise includes: starting at 40°C and maintaining for 1.2 minutes, then heating to 120°C at 105°C / min and maintaining for 2.5 minutes. The calibration equation is Area = 744.674825Amt 2 -94.31341Amt+20.200453, the gas to be tested is tested three times in parallel by gas chromatograph, and the peak area of ​​sulfur dioxide in the gas to be tested is obtained respectively. The peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation, and the volume concentration of sulfur dioxide in the gas to be tested is obtained respectively.

[0059] Example 3

[0060] The difference from Example 1 is that the working conditions of the gas chromatograph are set as follows: the temperature of the injection port is 140°C, the injection system is in split mode, the injection volume is 1 mL, the split ratio is 1.5:1, the temperature of the flame photometric detector is 205°C, the flow rate of the fuel gas is 55 mL / min, the flow rate of the auxiliary fuel gas is 80 mL / min, the flow rate of the tail gas is 60 mL / min, and the flow rate of the carrier gas is 6 mL / min; the column temperature is programmed, and the process of programmed temperature rise includes: starting at 40°C and maintaining for 1.5 minutes, then heating to 120°C at 110°C / min and maintaining for 3 minutes. The calibration equation is Area = 595.808633Amt 2 -75.523242Amt+16.171432, the gas to be tested is tested three times in parallel by gas chromatograph, and the peak area of ​​sulfur dioxide in the gas to be tested is obtained respectively. The peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation, and the volume concentration of sulfur dioxide in the gas to be tested is obtained respectively.

[0061] Example 4

[0062] The difference from Example 1 is that the process of programmed temperature increase includes: starting at 40°C and maintaining for 1.5 min, then increasing the temperature to 120°C at 110°C / min and maintaining for 3 min. The calibration equation is Area = 893.127253Amt 2-112.67078Amt+25.165642, the gas to be tested is tested three times in parallel by gas chromatograph, and the peak areas of sulfur dioxide in the gas to be tested are obtained respectively. The peak areas of sulfur dioxide in the gas to be tested are substituted into the calibration equation for calculation, and the volume concentrations of sulfur dioxide in the gas to be tested are obtained respectively.

[0063] Example 5

[0064] The difference from Example 1 is that the flow rate of the fuel gas is 45 mL / min, the flow rate of the auxiliary gas is 70 mL / min, the flow rate of the tail gas is 60 mL / min, and the flow rate of the carrier gas is 6 mL / min. The calibration equation is Area = 868.312808 Amt 2 -90.839274Amt+21.095894, the gas to be tested is tested three times in parallel by gas chromatograph, and the peak areas of sulfur dioxide in the gas to be tested are obtained respectively. The peak areas of sulfur dioxide in the gas to be tested are substituted into the calibration equation for calculation, and the volume concentrations of sulfur dioxide in the gas to be tested are obtained respectively.

[0065] Example 6

[0066] The difference from Example 1 is that the flow rate of the fuel gas is 55 mL / min, the flow rate of the auxiliary gas is 80 mL / min, the flow rate of the tail gas is 65 mL / min, and the flow rate of the carrier gas is 8 mL / min. The calibration equation is Area = 911.791699 Amt 2 -125.41122Amt+26.9666235. The gas to be tested is tested three times in parallel by gas chromatograph to obtain the peak areas of sulfur dioxide in the gas to be tested. The peak areas of sulfur dioxide in the gas to be tested are substituted into the calibration equation for calculation to obtain the volume concentrations of sulfur dioxide in the gas to be tested.

[0067] Example 7

[0068] The difference from Example 1 is that the split ratio of the injection system is 1.5:1, and the calibration equation is Area = 606.30594Amt 2 -94.0504615Amt+19.861944. The gas to be tested is tested three times in parallel by gas chromatograph to obtain the peak areas of sulfur dioxide in the gas to be tested. The peak areas of sulfur dioxide in the gas to be tested are substituted into the calibration equation for calculation to obtain the volume concentration of sulfur dioxide in the gas to be tested.

[0069] Example 8

[0070] The difference from Example 1 is that the split ratio of the injection system is 2:1, and the calibration equation is Area = 447.384421Amt2 -58.066049Amt+12.837398. The gas to be tested is tested three times in parallel by gas chromatograph to obtain the peak areas of sulfur dioxide in the gas to be tested. The peak areas of sulfur dioxide in the gas to be tested are substituted into the calibration equation for calculation to obtain the volume concentration of sulfur dioxide in the gas to be tested.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that the working conditions of the gas chromatograph are set as follows: the temperature of the injection port is 100°C, the column temperature is 150°C, the temperature of the flame photometric detector is 220°C, the flow rate of the fuel gas is 40mL / min, and the flow rate of the auxiliary fuel gas is 90mL / min. The calibration equation is Area = 892.301733Amt 2 -111.13678Amt+25.271247, the gas to be tested is tested three times in parallel by gas chromatograph, and the peak areas of sulfur dioxide in the gas to be tested are obtained respectively. The peak areas of sulfur dioxide in the gas to be tested are substituted into the calibration equation for calculation, and the volume concentrations of sulfur dioxide in the gas to be tested are obtained respectively.

[0073] Comparative Example 2

[0074] The difference from Example 1 is that the detector of the gas chromatograph is a TCD detector, and the gas to be tested is tested three times in parallel by the gas chromatograph, the peak area and standard curve of sulfur dioxide in the gas to be tested are calculated, and the volume concentration of sulfur dioxide in the gas to be tested is obtained.

[0075] The test results of the above embodiments and comparative examples are shown in Table 1.

[0076] Table 1

[0077]

[0078] It can be seen from Table 1 that the results of the determination method of the present application are reproducible. Among them, according to the test method of Comparative Example 2, due to the low concentration of sulfur dioxide in the gas to be tested, the test method cannot measure the peak, and therefore, the peak area and volume concentration of sulfur dioxide in the gas to be tested cannot be calculated. In Example 6, the carrier gas flow rate is as high as 8mL / min. If the gas chromatograph is operated according to this parameter for a long time, the life of the chromatographic column will be greatly reduced. The peak area values ​​obtained by the three parallel tests of Example 8 are all smaller than the peak area values ​​of Example 7, indicating that the response value of Example 8 is low.

[0079] in, Figure 1 It is a schematic diagram of the structure of a gas chromatograph. Figure 1 As can be seen from the figure, the gas chromatograph includes an injection valve 1, an injection port 2, a GS-Gaspro gas chromatography column 3 and a flame photometric detector 4.

[0080] Figure 2 This is a schematic diagram of the online dilution system structure of a gas chromatograph. Figure 2 It can be seen that the online dilution system includes a sulfur dioxide standard gas inlet 5, a dilution gas inlet 6, a mixed gas outlet 7 and a sulfur dioxide standard gas storage bottle 8.

[0081] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0082] In the detection method of sulfur dioxide content provided by the present application, the gas to be tested does not need to be pretreated and can be directly detected by gas chromatograph. Therefore, the detection method of the present invention is simple to operate and has high efficiency. Setting the conditions of the gas chromatograph within the above range is helpful to fully separate sulfur dioxide from other components in the sulfur dioxide standard gas or the gas to be tested, thereby helping to improve the precision and accuracy of sulfur dioxide detection. In step S2 and step S3, sulfur dioxide standard gas of different volume concentrations is detected by gas chromatograph, and different volume concentrations of sulfur dioxide and their corresponding peak areas are obtained, and calibration curves and calibration equations are established. The peak area of ​​sulfur dioxide in the gas to be tested is substituted into the calibration equation for calculation, and the volume concentration of sulfur dioxide in the gas to be tested can be simply and accurately calculated. According to the detection method of the present application, thanks to the control of the working conditions of the gas chromatograph and the precision and accuracy test results that can be achieved, the volume concentration of sulfur dioxide that can be detected by the detection method of the present application can reach 10 -6 Therefore, the method for detecting the sulfur dioxide content of the present invention has the advantages of high detection sensitivity, selectivity and stability.

[0083] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting sulfur dioxide content, characterized in that: The detection method comprises the following steps: Step S1, setting the working conditions of the gas chromatograph: the temperature of the injection port is 120-140°C, the column temperature is 40-120°C, the temperature of the flame photometer is 195-205°C, and the flow ratio of the fuel gas to the auxiliary fuel gas is 45-55:70-80; Step S2, selecting sulfur dioxide standard gas with known volume concentration for dilution to obtain sulfur dioxide standard gas with different volume concentrations; Step S3, detecting sulfur dioxide standard gas of different volume concentrations by gas chromatograph, obtaining sulfur dioxide of different volume concentrations and their corresponding peak areas, and establishing a calibration curve and a calibration equation by the two; Step S4, detecting the gas to be tested by the gas chromatograph to obtain the peak area of ​​sulfur dioxide in the gas to be tested; Step S5, substituting the peak area of ​​sulfur dioxide in the gas to be measured into the calibration equation for calculation to obtain the volume concentration of sulfur dioxide in the gas to be measured; Wherein, the peak area is the maximum value of the response value at the corresponding retention time of sulfur dioxide; The volume concentration of sulfur dioxide in the gas to be tested is 10 -6 (V / V) level.

2. The detection method according to claim 1, characterized in that In step S3, the calibration equation is: Area=BAmt 2 -CAmt+D; Where, Area is the peak area of ​​sulfur dioxide, Amt is the volume concentration of sulfur dioxide, and the unit of Amt is ×10 -6 (V / V), B is 447.384421~911.791699, C is 58.066049~125.41122, and D is 12.837398~26.9666235.

3. The detection method according to claim 1 or 2, characterized in that: In step S3 and step S4, the retention time of sulfur dioxide is independently 2.70 to 2.80 min; and / or the volume concentration of sulfur dioxide in the gas to be measured is 0.1 to 2.0×10 -6 (V / V).

4. The detection method according to any one of claims 1 to 3, characterized in that: In step S3, the chromatographic column of the gas chromatograph is subjected to adsorption saturation treatment before detection. The process of the adsorption saturation treatment is to pass sulfur dioxide standard gas into the gas chromatograph until the response value no longer increases, and after standing by for 8 to 10 hours, detect sulfur dioxide standard gas with the same volume concentration, and the response value no longer changes.

5. The detection method according to any one of claims 1 to 4, characterized in that: In step S1, the column temperature is programmed, and the process of programmed temperature increase includes: taking 40°C as the initial temperature and maintaining it for 1 to 1.5 minutes, then heating it to 120°C at a rate of 100 to 110°C / min and maintaining it for 2 to 3 minutes.

6. The detection method according to any one of claims 1 to 5, characterized in that: In step S1, the working conditions of the gas chromatograph also include: the tail gas is nitrogen, and the flow rate of the tail gas is 50-60 mL / min; and / or, the carrier gas is hydrogen, and the flow rate of the carrier gas is 4-6 mL / min.

7. The detection method according to any one of claims 1 to 6, characterized in that: The fuel gas is hydrogen, and the flow rate of the fuel gas is 45-50 mL / min; and / or the combustion-supporting gas is air, and the flow rate of the combustion-supporting gas is 70-75 mL / min.

8. The detection method according to any one of claims 1 to 7, characterized in that: In step S1, the chromatographic column of the gas chromatograph is a GS-Gaspro gas chromatographic column, and / or the inner diameter of the GS-Gaspro gas chromatographic column is 0.32 mm, and / or the length of the GS-Gaspro gas chromatographic column is 30 m.

9. The detection method according to any one of claims 1 to 7, characterized in that: In step S1, the gas chromatograph includes an injection system, and the sampler of the injection system is sulfur passivated; and / or the injection system includes an online dilution system; and / or the injection system is in split mode; and / or the split ratio of the injection system is 1:1 to 1.5:1; and / or the injection volume of the injection system is 1 mL.

10. The detection method according to claim 9, characterized in that: In step S2, the dilution is performed by the online dilution system; and / or the volume concentration of the sulfur dioxide standard gas is 10 to 20×10 -6 (V / V).

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