Analysis device and analysis method for preparing glycol by-product light dihydric alcohol from natural gas

Abstract

The invention discloses a device for analyzing byproduct light dihydric alcohol in preparation of ethylene glycol from natural gas, the device comprises a gas chromatograph, the gas chromatograph comprises a sample inlet, a chromatographic column, a chromatographic workstation and a hydrogen flame ionization detector, the device also comprises a thermal conductivity cell detector, the head end of the chromatographic column is connected with the sample inlet, and the tail end of the chromatographic column is connected with the thermal conductivity cell detector; the tail end of the chromatographic column is connected with an inlet of the thermal conductivity cell detector, an outlet of the thermal conductivity cell detector is respectively connected with an inlet of the hydrogen flame ionization detector and the chromatographic work station, and an outlet of the hydrogen flame ionization detector is also connected with the chromatographic work station. The problems that a light dihydric alcohol sample needs to be jointly analyzed by a plurality of instruments in the chromatographic analysis process, and errors are large when water is analyzed by using a Karl Fischer moisture meter are solved, and less equipment is needed.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection of light diols as a by-product of natural gas production of ethylene glycol, and in particular to an analysis device and an analysis method for light diols as a by-product of natural gas production of ethylene glycol. Background Art

[0002] Using natural gas as raw material, high-purity hydrogen and carbon monoxide are obtained after conversion, decarbonization and purification. Carbon monoxide reacts with methyl nitrite to synthesize dimethyl oxalate, and dimethyl oxalate reacts with hydrogen to synthesize crude ethylene glycol. Crude ethylene glycol is distilled to obtain polyester-grade ethylene glycol. During the distillation process, the crude ethylene glycol will collect the light components, lipids, propylene glycol, butanediol, hexanediol and other impurities extracted to the ethylene glycol concentration tower. Such materials are no longer used in the ethylene glycol production process because they contain high levels of ethylene glycol, 1,2-butanediol, and 2,3-butanediol. They still have high utilization value for fine chemical companies such as pesticides and plasticizers. Therefore, selling them as by-products will bring considerable economic benefits to the company.

[0003] The organic composition of light diols is relatively complex. Currently, 23 organic components have been measured. When using gas chromatography, two chromatographs are often used for joint analysis. When using a hydrogen flame ionization detector alone, there is no response to the water content in the sample, resulting in the water content in the organic composition of light diols to be measured separately using a volumetric Karl Fischer titrator. Since the water content in the sample is relatively large, about 20%-30%, the weighing error increases when using a volumetric Karl Fischer titrator due to the small sample weight, resulting in poor repeatability and low accuracy of the water analysis data. When using the current method for analysis, three instruments are needed to obtain all the data, which is a large workload, complex analysis process, and requires a high level of operator proficiency. More analysis errors may be introduced during the analysis process.

[0004] The present invention can solve the problem that a plurality of instruments need to be used for analysis during the analysis of light diol samples and the moisture data has a large error. Summary of the invention

[0005] In order to solve one or some technical problems existing in the prior art, one of the purposes of the present application is to provide an analysis device for light diols, a by-product of ethylene glycol production from natural gas, which solves the problem that light diol samples need to be analyzed by multiple instruments during the chromatographic analysis process and that there is still a large error when the moisture is analyzed using a Karl Fischer titrator, and less equipment is required.

[0006] The second purpose of the present application is to provide an analysis method for light diols, a by-product of the production of ethylene glycol from natural gas, which can obtain all the test data through a single injection, and has simple operation, reduces employee workload, reduces analysis errors, and improves the accuracy of analysis data.

[0007] In order to solve the above existing technical problems, one of the purposes of this application is achieved by adopting the following technical solution:

[0008] A device for analyzing light diols as a byproduct of natural gas production of ethylene glycol comprises a gas chromatograph, wherein the gas chromatograph comprises an injection port, a chromatographic column, a chromatographic workstation and a hydrogen flame ionization detector, and further comprises a thermal conductivity cell detector, wherein the head end of the chromatographic column is connected to the injection port, the tail end of the chromatographic column is connected to the inlet of the thermal conductivity cell detector, the outlet of the thermal conductivity cell detector is respectively connected to the inlet of the hydrogen flame ionization detector and the chromatographic workstation, and the outlet of the hydrogen flame ionization detector is also connected to the chromatographic workstation.

[0009] Preferably, it also includes an ultra-clean gas purifier whose inlet end is connected to the nitrogen pipeline, a first gas supply pipeline is provided between the gas outlet end of the ultra-clean gas purifier and the sample inlet, and the gas outlet end of the ultra-clean gas purifier is also provided with a second gas outlet pipeline respectively connected to the hydrogen flame ionization detector and the thermal conductivity cell detector, and the nitrogen output by the second gas outlet pipeline is respectively used as the tail gas of the hydrogen flame ionization detector, the tail gas of the thermal conductivity cell detector and the reference gas of the thermal conductivity cell detector.

[0010] Preferably, the chromatographic column adopts an HP-FFAP gas chromatography column, and a multi-step temperature increase program is set.

[0011] In order to solve the above existing technical problems, the second purpose of this application is achieved by adopting the following technical solution:

[0012] A method for analyzing light diols as a byproduct of natural gas-based ethylene glycol production, using an analysis device for analyzing light diols as a byproduct of natural gas-based ethylene glycol production, the analysis method comprising:

[0013] S1. Setting gas chromatograph parameters and establishing an analytical method for light diols;

[0014] S2. Conducting qualitative analysis on the components to be tested of the light diols by single standard determination;

[0015] S3. Quantitatively analyze the organic component content and water content of the light diol by mixed standard determination;

[0016] S4, sample collection and processing, on-site sampling using glass reagent bottles with threaded caps;

[0017] S5. Sample analysis.

[0018] Preferably, the parameters in step S1 are: injection volume is 0.4 μL; number of solvent washings before injection is 3; number of sample washings before injection is 3; number of solvent washings after injection is 4; split ratio is 80:1; vaporization chamber temperature is 300°C;

[0019] The chromatographic column is HP-FFAP 50.0m×0.32mm×0.50μm; the column flow rate is 1.31mL / min;

[0020] The detector temperature was 300.0°C; the tail gas flow rate was 30 mL / min; the hydrogen flow rate was 40 mL / min; and the air flow rate was 400 mL / min.

[0021] Preferably, the single standard preparation step in step S2 includes:

[0022] A1. Take a small amount of methylal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutyl alcohol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, triethylene glycol, and primary water into 24 chromatographic injection vials;

[0023] A2. Add an appropriate amount of ethylene glycol and shake well, and place each single label in the sample tray of the gas chromatograph autosampler;

[0024] A3. Run the analysis method of light diols in step S2, and conduct qualitative analysis on methylal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutanol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, triethylene glycol, and primary water to determine the retention time of each component.

[0025] Preferably, the mass ratio of the single standard component to ethylene glycol in the 24 chromatographic injection vials is 0.8-1.5:20.

[0026] Preferably, the light diol sample mixed standard preparation step in step S3 includes:

[0027] B1. Use a 100,000 ppm electronic balance to weigh 0.01500 g ± 10% each of ethylene carbonate, dimethyl oxalate, methylacetal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutyl alcohol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, 1,2-propylene glycol, γ-butyrolactone, 1,4-butanediol, diethylene glycol, 1,2-hexanediol, and triethylene glycol, about 0.15000 g ± 10% of 2,3-butanediol, about 1.05000 g ± 10% of 1,2-butanediol, about 0.75000 g ± 10% of ethylene glycol, and about 0.75000 g ± 10% of primary water in a 10 mL crimp bottle in advance and shake well.

[0028] B2. Transfer the mixed standard into a chromatographic injection vial and place it in the sample tray of the gas chromatograph automatic injector;

[0029] B3. Run the analysis method of light diols in step S3 to perform quantitative analysis on the sample, and use the correction area normalization method to establish a light diol analysis calibration curve.

[0030] Preferably, the samples in step S4 are sampled on-site using glass reagent bottles with threaded caps; after the samples are taken back to the laboratory, they are placed in a constant temperature water bath preheated to 80°C.

[0031] Preferably, the sample analysis step in step S5 includes:

[0032] C1. Take 1.0±0.1g of light diol sample into a chromatographic injection vial and place it in the sample tray of the gas chromatograph autosampler;

[0033] C2, running the analytical method of light diols in step S2;

[0034] C3. After the light diol analysis method is run, the quantitative calibration curve in step S3 is loaded to calibrate the chromatogram to obtain the contents of organic components and water in the light diol.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention can solve the problem that during the analysis of light diol samples, multiple instruments need to be used for analysis, and when the water content is measured using a volumetric Karl Fischer titrator, the weighing error increases due to the small sample weight, resulting in poor repeatability and low accuracy of the water content analysis data. All the data to be measured can be obtained through one injection, and the operation is simple, the workload of employees is reduced, the analysis error is reduced, and the accuracy of the analysis data is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the device connection structure of the invention;

[0038] Figure 2 A data reproducibility chromatogram for establishing a light diol analysis method with reference to the present invention;

[0039] Figure 3 A chromatogram for establishing a method for analyzing light diols with reference to the present invention;

[0040] In the figure: 1. Ultra-clean gas purifier; 2. Second gas outlet pipeline; 3. First gas supply pipeline; 4. Inlet; 5. Chromatographic column; 6. Thermal conductivity cell detector; 7. Chromatographic workstation; 8. Hydrogen flame ionization detector. DETAILED DESCRIPTION

[0041] Below, the present application is further described in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0042] In the description of the present application, it should be understood that the terms "up", "down", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0043] The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0044] Embodiment 1:

[0045] like Figure 1As shown, an analysis device for light diols as a by-product of natural gas production of ethylene glycol comprises a gas chromatograph, wherein the gas chromatograph comprises an injection port 4, a chromatographic column 5, a chromatographic workstation 7 and a hydrogen flame ionization detector 8, and further comprises a thermal conductivity cell detector 6, wherein the head end of the chromatographic column 5 is connected to the injection port 4, the tail end of the chromatographic column 5 is connected to the inlet of the thermal conductivity cell detector 6, the outlet of the thermal conductivity cell detector 6 is respectively connected to the inlet of the hydrogen flame ionization detector 8 and the chromatographic workstation 7, and the outlet of the hydrogen flame ionization detector 8 is also connected to the chromatographic workstation 7.

[0046] The connecting pipelines of the gas chromatograph gas circuit and the detector are improved, so that the head end of the improved chromatographic column 5 is connected to the injection port 4, the tail end is connected to the inlet of the thermal conductivity cell detector 6, the outlet of the thermal conductivity cell detector 6 is respectively connected to the inlet of the hydrogen flame ionization detector 8 and the chromatographic workstation 7, and the outlet of the hydrogen flame ionization detector 8 is also connected to the chromatographic workstation 7. When analyzing the complex organic composition of the light diol by-product of natural gas to ethylene glycol, since the thermal conductivity cell detector 6 is a non-destructive concentration detector, the thermal conductivity cell detector 6 responds to the moisture in the sample and does not destroy the composition of the sample; and the thermal conductivity cell detector 6 is connected in series with the hydrogen flame ionization detector 8 for gas chromatography analysis, so that the sample can be directly injected into the injection port 4 with an automatic injector, and the components to be tested are separated through the gas chromatography column 5, and all data of the content of the organic components and the moisture content of the light diol can be detected through one injection. This effectively solves the problem that during the analysis of light diol samples, multiple instruments such as gas chromatographs and volumetric Karl Fischer titrators need to be used for analysis, and the problem that the moisture data during the analysis still has large errors. During the entire operation, only one gas chromatograph is needed to achieve comprehensive one-time detection and obtain all accurate data, which effectively reduces the operating difficulty of operators, reduces employee workload, reduces analysis errors, and improves the accuracy of analysis data.

[0047] A further improvement is that it also includes an ultra-clean gas purifier 1 whose inlet end is connected to the nitrogen pipeline, a first gas supply pipeline 3 is provided between the gas outlet end of the ultra-clean gas purifier 1 and the sampling port 4, and the gas outlet end of the ultra-clean gas purifier 1 is also provided with a second gas outlet pipeline 2 connected to the hydrogen flame ionization detector 8 and the thermal conductivity cell detector 6 respectively, and the nitrogen output by the second gas outlet pipeline 2 is respectively used as the tail gas of the hydrogen flame ionization detector 8, the tail gas of the thermal conductivity cell detector 6 and the reference gas of the thermal conductivity cell detector 6.

[0048] Since the improved gas chromatograph will have large baseline noise and ghost peaks during detection, which affects the analysis accuracy of trace components in the sample, in order to solve this problem, an ultra-clean gas purifier 1 is added. By adding the ultra-clean gas purifier 1, hydrocarbons and moisture in the nitrogen can be effectively removed to provide stable high-purity nitrogen, thereby preventing baseline fluctuations and ghost peaks and improving the accuracy of the analysis results.

[0049] A further improvement is that the chromatographic column 5 adopts a HP-FFAP gas chromatographic column 5 and a multi-step temperature rising program is set.

[0050] Light glycol, a by-product of ethylene glycol production from natural gas, is liquid at room temperature. When a thermal conductivity cell detector 6 is used in series with a hydrogen flame ionization detector 8 for gas chromatography analysis, a HP-FFAP gas chromatography column 5 with strong water resistance is used, and a multi-step heating program is set up at the same time, so that the sample can be directly injected into the injection port 4 with an automatic sampler, and the components to be measured are separated by the gas chromatography column 5, so that all the data to be measured can be obtained through a single injection.

[0051] Embodiment 2:

[0052] like Figure 2 and Figure 3 As shown, a method for analyzing light diols as a byproduct of natural gas production of ethylene glycol is provided. The method adopts an analysis device for analyzing light diols as a byproduct of natural gas production of ethylene glycol. The analysis steps include:

[0053] S1. Setting gas chromatograph parameters and establishing an analytical method for light diols;

[0054] The parameters are as follows: injection volume is 0.4 μL; number of solvent washes before injection is 3; number of sample washes before injection is 3; number of solvent washes after injection is 4; split ratio is 80:1; vaporization chamber temperature is 300°C;

[0055] The chromatographic column is HP-FFAP 50.0m×0.32mm×0.50μm; the column flow rate is 1.31mL / min;

[0056] The detector temperature was 300.0°C; the tail gas flow rate was 30 mL / min; the hydrogen flow rate was 40 mL / min; and the air flow rate was 400 mL / min.

[0057] The detailed parameters are: injection volume: 0.4μL; number of solvent washes before injection: 3; number of sample washes before injection: 3; number of solvent washes after injection: 4; split ratio: 80:1; vaporization chamber temperature: 300℃; purge flow rate: 3.0mL / min; column flow rate: 1.31mL / min; column: HP-FFAP 50.0m×0.32mm×0.50μm; heating program: initial temperature is 80℃, keep for 5min; first-order heating rate is 10℃ / min, heating to 140℃, keep for 6min; second-order heating rate is 10℃ / min, heating to 240℃, keep for 3min; total analysis time: 30min; detector: hydrogen flame ionization detector, temperature 300℃; nitrogen is used as carrier gas, hydrogen as fuel gas, and air as auxiliary gas, hydrogen: air = 1:10, tail gas flow rate: 30mL / min; hydrogen flow rate: 40mL / min; air flow rate: 400mL / min.

[0058] Among them, the technical indicators of gas chromatograph include:

[0059] (1) Column temperature box: located on the main unit of the gas chromatograph, it stably controls the operating temperature of the chromatographic column to ensure the separation effect of the chromatographic column.

[0060] A. Temperature range: Low temperature: 10℃ above room temperature, high temperature ≥420℃

[0061] B. Temperature setting: ≤0.1℃;

[0062] C. Heating speed: slowest 0.1℃ / min, fastest ≥120℃ / min

[0063] D. Temperature stability: better than 0.01℃ when the ambient temperature changes by 1℃

[0064] E. Temperature program: 20 steps 21 platform

[0065] F. Maximum running time: 999.99 minutes

[0066] (2) Capillary column split / splitless inlet: Located at the top of the gas chromatograph mainframe, the sample is introduced into the gas chromatography system and vaporized here, and then carried into the chromatographic column by the carrier gas for separation and analysis.

[0067] A. Maximum operating temperature: 400℃

[0068] B. Electronic parameters set pressure, flow rate and split ratio, the maximum split ratio is not less than 5000:1

[0069] C. Pressure setting range: 0-150Psi

[0070] D. Flow rate setting range: N2: 0-600ml / min, H2: 0-500ml / min and above

[0071] (3) Electronic Pressure Control (EPC): Located in the main unit of the gas chromatograph, it uses high-precision pressure control to set pressure and flow parameters and automatically adjust the carrier gas flow rate to meet different analysis requirements.

[0072] A. Control accuracy is not less than 0.01psi; automatic temperature and pressure compensation

[0073] B. Retention time reproducibility: <0.008%

[0074] C. Peak area reproducibility: <1% RSD

[0075] (4) Hydrogen flame ionization detector: Located on the top of the gas chromatograph main unit, it detects and identifies the separated organic components.

[0076] A. Maximum operating temperature: 420℃

[0077] B. Minimum detection limit: 3pg C / s (dodecane)

[0078] C. Linear dynamic range: ≥107

[0079] (5) Liquid automatic sampler: installed above the main unit of the gas chromatograph and connected to the sample inlet. It automatically completes the sample injection process, thereby improving analysis efficiency, reducing injection costs, and improving the accuracy and reproducibility of analysis data.

[0080] A. Same brand as chromatograph, double tower injection.

[0081] B.15 sample bottle positions, excluding cleaning bottles

[0082] C. Cross contamination: less than 10-4 (using 4 solvents for cleaning, determining 1% biphenyl in n-hexane)

[0083] In step 2, an analytical method for light diols is established, and its detailed parameters include:

[0084] (1) Gas system

[0085] Nitrogen was used as carrier gas, hydrogen as fuel gas, and air as auxiliary fuel gas, with hydrogen: air = 1:10, tail gas flow rate: 30 mL / min; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min.

[0086] (2) The injection system includes

[0087] Injection volume: 0.4 μL; number of solvent washes before injection: 3; number of sample washes before injection: 3; number of solvent washes after injection: 4; split ratio: 80:1; vaporization chamber temperature: 300 °C; purge flow: 3.0 mL / min; column flow: 1.31 mL / min;

[0088] (3) Separation system includes

[0089] Chromatographic column: HP-FFAP 50.0m×0.32mm×0.50μm; Temperature program: initial temperature 80℃, hold for 5min; first-order heating rate 10℃ / min, heating to 140℃, hold for 6min; second-order heating rate 10℃ / min, heating to 240℃, hold for 3min; total analysis time: 30min;

[0090] (4) Detection system includes

[0091] Detector 1: Hydrogen flame ionization detector, temperature 300°C;

[0092] Detector 2: thermal conductivity cell detector, temperature 200°C;

[0093] (5) Data processing system includes

[0094] High-precision control QA / QC function supports automatic calculation of methodological indicators such as noise, drift, signal-to-noise ratio, LOD, LOQ, precision and recovery rate, and has instrument system inspection function and user safety management function.

[0095] The thermal conductivity detector only retains the water chromatographic peak, while the hydrogen flame ionization detector retains the chromatographic peaks of all organic components.

[0096] S2. Conducting qualitative analysis on the components to be tested of the light diols by single standard determination;

[0097] S3. Quantitatively analyze the organic component content and water content of the light diol by mixed standard determination;

[0098] S4, sample collection and processing, on-site sampling using glass reagent bottles with threaded caps;

[0099] S5. Sample analysis.

[0100] Further improved, the single standard preparation step in step S2 includes:

[0101] A1. Take a small amount of methylal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutyl alcohol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, triethylene glycol, and primary water into 24 chromatographic injection vials;

[0102] A2. Add an appropriate amount of ethylene glycol and shake well, and place each single label in the sample tray of the gas chromatograph autosampler;

[0103] A3, the analysis method of the light diol in the operation step S2, methylal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butyl alcohol, isobutyl alcohol, n-butyl alcohol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, ethylene glycol, 1,2-propylene glycol, 1,2-butylene glycol, 2,3-butylene glycol, γ-butyrolactone, dimethyl oxalate, 1,4-butylene glycol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, triethylene glycol, and primary water are qualitatively analyzed to determine the retention time of each component. Its specific preparation is shown in Table 1.

[0104] Table 1: Light diols single standard

[0105]

[0106]

[0107] By taking a small amount of 24 single-standard reference substances and shaking them evenly with ethylene glycol, a comprehensive qualitative analysis of the components to be tested can be achieved, thus solving the problem of incomplete testing of components in mixed standard samples.

[0108] Preferably, the mass ratio of the single standard component to ethylene glycol in the 24 chromatographic injection vials is 0.8-1.5:20. Within this ratio range, the chromatographic peak retention times of the component to be tested, ethylene glycol, and other impurities in the single standard can be effectively distinguished.

[0109] Preferably, the light diol sample mixed standard preparation step in step S3 includes:

[0110] B1. Use a 100,000 ppm electronic balance to weigh 0.01500 g ± 10% each of ethylene carbonate, dimethyl oxalate, methylacetal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutyl alcohol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, 1,2-propylene glycol, γ-butyrolactone, 1,4-butanediol, diethylene glycol, 1,2-hexanediol, and triethylene glycol, about 0.15000 g ± 10% of 2,3-butanediol, about 1.05000 g ± 10% of 1,2-butanediol, about 0.75000 g ± 10% of ethylene glycol, and about 0.75000 g ± 10% of primary water in a 10 mL crimp bottle in advance and shake well.

[0111] B2. Transfer the mixed standard into a chromatographic injection vial and place it in the sample tray of the gas chromatograph automatic injector;

[0112] B3. Run the analysis method of light diols in step S3, perform quantitative analysis on the sample, and use the correction area normalization method to establish a light diol analysis calibration curve. See Table 2 for detailed parameters of the mixed standard.

[0113] Table 2: Light diol standard samples

[0114]

[0115]

[0116]

[0117] The mixed standard should be used as soon as possible after preparation to avoid alcohol-ester exchange reaction among the components in the mixed standard, which would affect the actual concentration of the components in the mixed standard sample. The dissolution rate of chromatographically pure or analytical standard dimethyl oxalate is slow, and it can be accelerated by ultrasonic dissolution in an ultrasonic cleaner.

[0118] A further improvement is that the samples in step S4 are sampled on-site using glass reagent bottles with threaded caps; after the samples are taken back to the laboratory, they are placed in a constant temperature water bath preheated to 80°C.

[0119] Since the organic component dimethyl oxalate in the sample may easily crystallize upon cooling if not handled in time after being sampled on-site through a glass reagent bottle, in order to avoid crystallization, after the sample is taken back to the laboratory, it should be placed in a constant temperature water bath preheated to 80°C to prevent the organic component dimethyl oxalate in the sample from crystallizing upon cooling.

[0120] Further improved, the sample analysis step in step S5 includes:

[0121] C1. Take 1.0±0.1g of light diol sample into a chromatographic injection vial and place it in the sample tray of the gas chromatograph autosampler;

[0122] C2, running the analytical method of light diols in step S2;

[0123] C3. After the light diol analysis method is run, the quantitative calibration curve in step S3 is loaded to calibrate the chromatogram to obtain the contents of organic components and water in the light diol.

[0124] Take about 1.0g of light diol sample in a chromatographic injection vial, place it in the sample tray of the gas chromatograph automatic injector, and run the light diol analysis method in step S2. The sample passes through a chromatographic column, a thermal conductivity cell detector, a hydrogen flame ionization detector, and a workstation to obtain a chromatogram of each component of the sample, and the chromatogram is processed so that the thermal conductivity cell detector only retains the chromatographic peak of water, and the hydrogen flame ionization detector retains the chromatographic peaks of all other organic components.

[0125] After the light diol analysis method is run, the quantitative calibration curve in step 3 is loaded to calibrate the chromatogram to obtain the content of organic components and water in the light diol.

[0126] pass Figure 2 and Figure 3 It can be seen that the light diol analysis method established with reference to the present invention is used for data repeatability chromatographic analysis, which has stable operation and high repeatability of analysis data; and the effect of obtaining the contents of all components through one injection can be achieved.

[0127] The above-mentioned implementation modes are only preferred implementation modes of the present application and cannot be used to limit the scope of protection of the present application. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present application shall fall within the scope of protection required by the present application.

Claims

1. An analytical device for light glycols as a by-product of natural gas to ethylene glycol production, comprising a gas chromatograph, characterized in that: The gas chromatograph comprises an injection port (4), a chromatographic column (5), a chromatographic workstation (7) and a hydrogen flame ionization detector (8), and further comprises a thermal conductivity cell detector (6), wherein the head end of the chromatographic column (5) is connected to the injection port (4), the tail end of the chromatographic column (5) is connected to the inlet of the thermal conductivity cell detector (6), the outlet of the thermal conductivity cell detector (6) is respectively connected to the inlet of the hydrogen flame ionization detector (8) and the chromatographic workstation (7), and the outlet of the hydrogen flame ionization detector (8) is also connected to the chromatographic workstation (7).

2. The analysis device for light glycol as a by-product of natural gas to ethylene glycol according to claim 1, characterized in that: It also comprises an ultra-clean gas purifier (1) whose inlet end is connected to a nitrogen pipeline, a first gas supply pipeline (3) being provided between the gas outlet end of the ultra-clean gas purifier (1) and the sample inlet (4), a second gas outlet pipeline (2) being provided at the gas outlet end of the ultra-clean gas purifier (1) and being respectively connected to the hydrogen flame ionization detector (8) and the thermal conductivity cell detector (6), and the nitrogen gas outputted from the second gas outlet pipeline (2) being respectively used as tail gas for the hydrogen flame ionization detector (8), tail gas for the thermal conductivity cell detector (6) and reference gas for the thermal conductivity cell detector (6).

3. The analysis device for light glycol as a by-product of natural gas to ethylene glycol according to claim 2, characterized in that: The chromatographic column (5) adopts a HP-FFAP gas chromatographic column, and a multi-step temperature increase program is set.

4. A method for analyzing light diols as a by-product of natural gas to ethylene glycol production, characterized in that: The method comprises using the analytical device for analyzing the light glycol by-product of natural gas to ethylene glycol as described in any one of claims 1 to 3, wherein the analytical method comprises: S1. Setting gas chromatograph parameters and establishing an analytical method for light diols; S2. Conducting qualitative analysis on the components to be tested of the light diols by single standard determination; S3. Quantitatively analyze the organic component content and water content of the light diol by mixed standard determination; S4, sample collection and processing, on-site sampling using glass reagent bottles with threaded caps; S5. Sample analysis.

5. The method for analyzing light glycol as a by-product of natural gas to ethylene glycol according to claim 4, characterized in that: The parameters in step S1 are: injection volume is 0.4 μL; number of solvent washings before injection is 3; number of sample washings before injection is 3; number of solvent washings after injection is 4; split ratio is 80:1; vaporization chamber temperature is 300°C; The chromatographic column (5) is HP-FFAP 50.0m×0.32mm×0.50μm; the flow rate of the chromatographic column (5) is 1.31mL / min; the detector temperature is 300.0℃; the tail gas flow rate is 30mL / min; the hydrogen flow rate is 40mL / min; and the air flow rate is 400mL / min.

6. The method for analyzing light glycol as a by-product of natural gas to ethylene glycol according to claim 4, characterized in that: The single standard preparation step in step S2 comprises: A1. Take a small amount of methylal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutyl alcohol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, triethylene glycol, and primary water into 24 chromatographic injection vials; A2. Add an appropriate amount of ethylene glycol and shake well, and place each single label in the sample tray of the gas chromatograph autosampler; A3. Run the analysis method of light diols in step S2, and conduct qualitative analysis on methylal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutanol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, triethylene glycol, and primary water to determine the retention time of each component.

7. The method for analyzing light glycol as a by-product of natural gas to ethylene glycol according to claim 6, characterized in that: The mass ratio of the single standard component to ethylene glycol in the 24 chromatographic injection vials was 0.8 to 1.5:

20.

8. The method for analyzing light glycol as a by-product of natural gas to ethylene glycol according to claim 4, characterized in that: The light diol sample mixed standard preparation step in step S3 includes: B1. Use a 100,000 ppm electronic balance to weigh 0.01500 g ± 10% each of ethylene carbonate, dimethyl oxalate, methylacetal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutyl alcohol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, 1,2-propylene glycol, γ-butyrolactone, 1,4-butanediol, diethylene glycol, 1,2-hexanediol, and triethylene glycol, about 0.15000 g ± 10% of 2,3-butanediol, about 1.05000 g ± 10% of 1,2-butanediol, about 0.75000 g ± 10% of ethylene glycol, and about 0.75000 g ± 10% of primary water in a 10 mL crimp bottle in advance and shake well. B2. Transfer the mixed standard into a chromatographic injection vial and place it in the sample tray of the gas chromatograph automatic injector; B3. Run the analysis method of light diols in step S3 to perform quantitative analysis on the sample, and use the correction area normalization method to establish a light diol analysis calibration curve.

9. The method for analyzing light glycol as a by-product of natural gas to ethylene glycol according to claim 4, characterized in that: The samples in step S4 are collected on-site using glass reagent bottles with threaded caps; after the samples are taken back to the laboratory, they are placed in a constant temperature water bath preheated to 80°C.

10. The method for analyzing light glycol as a by-product of natural gas to ethylene glycol according to claim 4, characterized in that: The sample analysis step in step S5 includes: C1. Take 1.0±0.1g of light diol sample into a chromatographic injection vial and place it in the sample tray of the gas chromatograph autosampler; C2, running the analytical method of light diols in step S2; C3. After the light diol analysis method is run, the quantitative calibration curve in step S3 is loaded to calibrate the chromatogram to obtain the contents of organic components and water in the light diol.

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