An apparatus for analyzing heavy diols as a byproduct of natural gas to ethylene glycol

Abstract

The application discloses a kind of natural gas preparation ethyleneglycol byproduct heavy glycol analytical device, including gas chromatograph, gas chromatograph includes sample inlet, chromatographic column one, workstation, column oven and hydrogen flame ionization detector one, the two ends of chromatographic column one are respectively connected the inlet of sample inlet and hydrogen flame ionization detector one, hydrogen flame ionization detector one outlet is connected with workstation, sample inlet and workstation are also provided with chromatographic column two, hydrogen flame ionization detector two and aging box, the two ends of chromatographic column two are respectively connected the inlet of sample inlet and hydrogen flame ionization detector two, hydrogen flame ionization detector two outlet is connected with workstation, the programmed temperature process of chromatographic column one is completed in column oven, the programmed temperature process of chromatographic column two is completed in aging box. Solve the problem that heavy glycol sample is long in chromatographic analysis process, separation effect is poor.

Description

Technical Field

[0001] This invention relates to the field of analytical detection technology for heavy diols, a byproduct of ethylene glycol production from natural gas, and specifically to an analytical apparatus for heavy diols, a byproduct of ethylene glycol production from natural gas. Background Technology

[0002] Using natural gas as raw material, high-purity hydrogen and carbon monoxide are obtained through conversion, decarbonization, and purification. Carbon monoxide reacts with methyl nitrite to synthesize dimethyl oxalate, which then reacts with hydrogen to synthesize crude ethylene glycol. The crude ethylene glycol is then distilled to obtain polyester-grade ethylene glycol. During the distillation process, heavy components, lipids, propylene glycol, butanediol, hexanediol, and other heavy diol impurities are collected in the ethylene glycol concentration tower. These heavy diol materials are no longer utilized in the ethylene glycol production process. However, because they contain high levels of ethylene glycol, diethylene glycol, and triethylene glycol, they can improve the flexibility and plasticity of polyester resins, polyurethane resins, unsaturated resins, polycarbonates, diacrylates, and diglycidyl ethers. When used as additives in certain lubricant formulations, they can improve lubrication and corrosion resistance. Therefore, they still have significant utilization value in fine chemical enterprises, and selling them as byproducts can bring considerable economic benefits.

[0003] However, since heavy diols are fusel oils, they contain high levels of heavy and high-boiling-point components, but also small amounts of low-boiling-point alcohols and esters with boiling points close to those of the high-boiling-point substances. When using conventional methods with chromatographic columns for analysis, the simultaneous analysis of low-boiling-point and multiple high-boiling-point components requires reducing the carrier gas flow rate and the programmed temperature rise rate, resulting in a long analysis time. Furthermore, the high-boiling-point component peaks may merge or overlap, necessitating manual peak accumulation. Manual peak accumulation is susceptible to human error, thus compromising repeatability and leading to poor repeatability and accuracy of the resulting analytical data.

[0004] Therefore, it is necessary to improve existing gas chromatographs to shorten the analysis time and solve the problem of difficult separation of high-boiling-point alcohol ester components on the chromatographic column when analyzing heavy diols. Summary of the Invention

[0005] In order to solve one or more technical problems existing in the prior art, one of the objectives of this application is to provide an analytical device for heavy diols, a byproduct of ethylene glycol production from natural gas, which solves the problems of long analysis time and poor separation effect of heavy diol samples in chromatographic analysis.

[0006] The second objective of this application is to provide an analytical method for heavy diols, a byproduct of ethylene glycol production from natural gas. This method allows for the acquisition of all test data with a single injection, and is simple to operate, reduces employee workload, minimizes analytical errors, and improves the accuracy of analytical data.

[0007] To address the aforementioned technical problems, one of the objectives of this application is achieved through the following technical solution:

[0008] An analytical apparatus for the production of heavy diols, a byproduct of ethylene glycol from natural gas, includes a gas chromatograph. The gas chromatograph includes an injection port, a first chromatographic column, a workstation, a column oven, and a first flame ionization detector (FID). The two ends of the first chromatographic column are connected to the injection port and the inlet of the first FID, respectively. The outlet of the first FID is connected to the workstation. A second chromatographic column, a second FID, and an aging chamber are also provided between the injection port and the workstation. The two ends of the second chromatographic column are connected to the injection port and the inlet of the second FID, respectively. The outlet of the second FID is connected to the workstation. The programmed temperature rise process for the first chromatographic column is completed within the column oven, and the programmed temperature rise process for the second chromatographic column is completed within the aging chamber.

[0009] When analyzing the complex organic composition of heavy diols, a byproduct of ethylene glycol production from natural gas, the system can automatically inject the liquid to be analyzed through the injection port and deliver it to two different chromatographic columns (column one and column two). Low-boiling-point components are programmed to rise on column one using the gas chromatograph's built-in column oven, while high-boiling-point components are programmed to rise on column two using an added aging chamber. This effectively solves the problems of long analysis time and difficulty in separating high-boiling-point components, reduces the operational difficulty for operators, reduces the workload of employees, reduces analytical errors, and improves the accuracy of analytical data.

[0010] Preferably, it also includes an ultra-clean gas purifier whose inlet end is connected to nitrogen, hydrogen, and air pipelines.

[0011] An ultra-clean gas purifier was added. By adding the ultra-clean gas purifier, not only can hydrocarbons and moisture in nitrogen be effectively removed, but also moisture and dust in hydrogen and air can be removed. This provides the gas chromatograph with a stable supply of high-purity nitrogen, high-purity hydrogen, and clean air. This not only prevents baseline fluctuations and ghost peaks, improving the accuracy of analytical results, but also ensures the heating rate of the column 2 in the aging chamber and the stability of the detector's internal circuitry or electronic components. Furthermore, it prevents dust particles from clogging the detector nozzles or depositing on the electrode surface, thus affecting ion collection efficiency.

[0012] Preferably, the nitrogen outlet of the ultra-clean gas purifier is connected to the sample inlet, the first hydrogen flame ionization detector, and the second hydrogen flame ionization detector, respectively.

[0013] Preferably, the hydrogen outlet of the ultra-clean gas purifier is connected to the hydrogen flame ionization detector one and the hydrogen flame ionization detector two, respectively.

[0014] Preferably, the air outlet of the ultra-clean gas purifier is connected to the first hydrogen flame ionization detector and the second hydrogen flame ionization detector, respectively.

[0015] Preferably, the first chromatographic column is an HP-FFAP gas chromatographic column, and the second chromatographic column is a DB-624 gas chromatographic column, both of which are equipped with multi-stage temperature programs.

[0016] Heavy diols, a byproduct of natural gas-to-ethylene glycol production, are liquid at room temperature. When using two sets of parallel hydrogen flame ionization detectors for gas chromatography analysis, low-boiling-point components are analyzed using an HP-FFAP gas chromatography column, while high-boiling-point components are analyzed using a DB-624 gas chromatography column. A multi-stage temperature program is also set, allowing for direct injection of the sample into the autosampler-equipped inlet. The two gas chromatography columns then perform targeted separation of the analytes, enabling the acquisition of all analytical data with a single injection, effectively shortening the analysis time.

[0017] Preferably, the aging chamber is 480mm long, 750mm wide, and 520mm high; the maximum operating temperature is 400℃; the temperature control accuracy is ±0.1℃; the power is 2kW; and the voltage is 220V.

[0018] Since the temperature ramp rate of column 2 in the aging chamber is higher than that of column 1, independently aging column 2 can be heated independently to ensure the temperature ramp rate and enable automatic injection.

[0019] Preferably, the column oven is located on the main unit of the gas chromatograph and is used to stably control the operating temperature of the first chromatographic column to ensure the separation effect of the first chromatographic column.

[0020] Preferably, the injection port is a capillary column split / splitless injection port: located at the top of the gas chromatograph main unit, 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.

[0021] Preferably, the electronic pressure control (EPC) of the gas chromatograph is located inside the gas chromatograph main unit. Through high-precision pressure control, pressure and flow parameters are set, and the carrier gas flow rate is automatically adjusted to adapt to different analytical needs.

[0022] Preferably, the hydrogen flame ionization detector is located on the top of the gas chromatograph main unit to detect and identify the separated organic components.

[0023] Preferably, the automatic liquid sampler is installed above the gas chromatograph and connected to the injection port. This automates the sample injection process, thereby improving analytical efficiency, reducing injection costs, and enhancing the accuracy and reproducibility of analytical data.

[0024] The second objective of this application is achieved through the following technical solution:

[0025] A method for analyzing heavy diols, a byproduct of ethylene glycol production from natural gas, comprising the following steps: using a heavy diol analysis device for ethylene glycol production from natural gas, the method includes the following steps for analyzing the heavy diols using the analysis device:

[0026] S1. Set the gas chromatograph parameters as follows:

[0027] The injection volume at the injection port is 0.4 μL;

[0028] Column: HP-FFAP, 50.0m × 0.32mm × 0.50μm, flow rate: 1.31mL / min; temperature program: initial temperature 40℃, hold for 2min; first-order temperature ramp rate: 10℃ / min, ramp to 140℃, hold for 6min, analysis time 18min;

[0029] Column 2 DB-624: 60m × 0.25mm × 1.40µm, flow rate 1.53mL / min; temperature program: initial temperature 120℃, hold for 2min; first-order temperature ramp rate 15℃ / min, ramp to 180℃, hold for 6min; second-order temperature ramp rate 10℃ / min, ramp to 220℃, hold for 2min; analysis time: 18min;

[0030] The temperature of the two detectors was 300.0℃, the flow rate of the tail gas was 30 mL / min, the flow rate of hydrogen was 40 mL / min, and the flow rate of air was 400 mL / min;

[0031] S2. Establish a standard curve for heavy diols: After preparing single standards and mixed standards, run a gas chromatograph. Perform qualitative analysis of the analytes in heavy diols by single standard determination; perform quantitative analysis of the organic components in heavy diols by mixed standard determination; and establish a mixed standard quantitative calibration curve for heavy diols.

[0032] S3. Sample collection and processing: Samples are collected on-site using glass reagent bottles with screw caps.

[0033] S4. Sample analysis: The system generates component chromatograms.

[0034] Preferably, in step S1, the number of solvent cleaning cycles before injection is 3; the number of sample cleaning cycles before injection is 3; the number of solvent cleaning cycles after injection is 4; and the split ratio is 80±5:1.

[0035] Because continuous automated injection analysis is used, multiple solvent washes before and after injection remove residues from the previous sample, ensuring the chromatographic autosampler needle is clean and does not contaminate the sample to be analyzed. In particular, four solvent washes after injection effectively prevent incomplete removal of sample residues. A split ratio that is too small can lead to peak merging or overlap, while a split ratio that is too large results in poor peak shape, small peak area, and unresponsive trace components. Therefore, a split ratio of 75–85:1 produces better peak shape, especially at a split ratio of 80:1.

[0036] Preferably, the single standard preparation step in step S2 includes:

[0037] A1. Take small amounts of methyl acetal, 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-propanediol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, and triethylene glycol into 23 chromatographic vials.

[0038] A2. Add an appropriate amount of ethylene glycol to each vial and shake well. Place each single standard in the sample tray of the gas chromatograph's autosampler.

[0039] A3. The analytical method for heavy diols in step S2 is used to qualitatively analyze 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-propanediol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, and triethylene glycol to determine the retention time of each component.

[0040] Preferably, the mass ratio of the single standard component to ethylene glycol in the 23 chromatographic injection vials is 1:10.

[0041] It can solve the problem of the difference between the retention time of each component and the actual sample. After being configured at a ratio of 1:10, the retention time of each component can be made close to that of the actual sample.

[0042] Preferably, the heavy diol sample mixed standard preparation step in step S2 includes:

[0043] B1. Using a 100,000 ppm electronic balance, weigh the following components in sequence: ethylene carbonate, dimethyl oxalate, methyl acetal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutanol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, 1,2-propanediol, γ-butyrolactone, 1,4-butanediol, 1,2-hexanediol, 2,3-butanediol, and 1,2-butanediol, approximately 0.35000 g ± 10% of diethylene glycol and triethylene glycol, and approximately 2.10000 g ± 10% of ethylene glycol into a 10 mL clamp-top bottle and shake well.

[0044] B2. Transfer the mixed standard into the chromatographic injection vial and place it in the sample tray of the gas chromatograph's autosampler.

[0045] B3. Run the analytical method for heavy diols in step S2 to perform quantitative analysis on the sample, and use the calibration area normalization method to establish a calibration curve for heavy diol analysis.

[0046] By using the calibration area normalization method, a calibration curve for the analysis of heavy diols can be established. This allows the established standard working curve to directly obtain the ratio of peak area to content for each analyte. As a result, when analyzing actual samples, the specific content can be determined directly after obtaining the peak area, significantly shortening the analysis time. It also avoids the problem of high-boiling-point component chromatographic peaks connecting or overlapping, which necessitates manual peak accumulation, resulting in high repeatability and accuracy of the analytical data.

[0047] Preferably, the sample analysis step in step S4 includes:

[0048] C1. Take 1.0±0.1g of heavy diol sample into a chromatographic vial and place it in the sample tray of the gas chromatograph's autosampler;

[0049] C2. Run the analytical method for heavy diols in step S2;

[0050] C3. After the heavy diol analysis method is completed, a quantitative calibration curve is loaded to correct the chromatogram, and the contents of organic components and water in the heavy diol can be obtained.

[0051] Preferably, the ratio of hydrogen to air in step S2 is 1:10.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0053] By introducing a second chromatographic column and an aging chamber, the analytical efficiency of heavy diols was significantly improved, achieving efficient separation of high-boiling-point alcohol ester components such as ethylene glycol, 1,2-butanediol, 1,4-butanediol, 2,3-butanediol, γ-butyrolactone, ethylene carbonate, diethylene glycol, and triethylene glycol. Compared with traditional methods, this method solves the problems of long analysis time and difficult component separation in conventional chromatographic columns for heavy diol samples, significantly shortening the analysis time, improving separation efficiency and the accuracy of analytical data. It allows for obtaining all analyte data with a single injection, eliminating the need for manual chromatogram processing and reducing staff workload. This technological improvement provides a more convenient and efficient solution for research in related fields, contributing to the further development of related analytical techniques. Attached Figure Description

[0054] Figure 1 A schematic diagram of the device connection structure for the invention;

[0055] Figure 2 To establish a repeatability chromatogram for the heavy diol analysis method based on the present invention;

[0056] Figure 3 The chromatogram for the analytical method of heavy diols established with reference to the present invention;

[0057] In the diagram: 1. Nitrogen, hydrogen, and air pipelines; 2. Ultra-clean gas purifier; 3. Flame ionization detector I; 4. Workstation; 5. Flame ionization detector II; 6. Column II; 7. Aging chamber; 8. Column oven; 9. Injector; 10. Column I. Detailed Implementation

[0058] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0059] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0060] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship. Example

[0061] like Figure 1 As shown, an analytical apparatus for heavy diols, a byproduct of ethylene glycol production from natural gas, includes a gas chromatograph (GC). The GC includes an injection port 9, a column 10, a workstation 4, a column oven 8, and a flame ionization detector 3. The two ends of the column 10 are connected to the injection port 9 and the inlet of the flame ionization detector 3, respectively. The outlet of the flame ionization detector 3 is connected to the workstation 4. Between the injection port 9 and the workstation 4, a second column 6, a second flame ionization detector 5, and an aging chamber 7 are also provided. The two ends of the second column 6 are connected to the injection port 9 and the flame ionization detector 5, respectively. The inlet of detector 25, column 10 is located in column oven 8, column 26 is located in aging chamber 7, and one path of column 10 and flame ionization detector 3 and one path of column 26 and flame ionization detector 25 are connected in parallel between injection port 9 and workstation 4. The programmed temperature rise process of column 10 is completed in column oven 8, and the programmed temperature rise process of column 26 is completed in aging chamber 7. After staged programmed temperature rise of column 10 by column oven 8, the analysis of low boiling point components is realized. After staged programmed temperature rise of column 26 by aging chamber 7, the analysis of high boiling point components is realized.

[0062] The main technical specifications of the gas chromatograph components are as follows:

[0063] (1) Gas Chromatograph: The electronic pressure control (EPC) on the gas chromatograph is located inside the gas chromatograph main unit. Through high-precision pressure control, it sets pressure and flow parameters and automatically adjusts the carrier gas flow rate to adapt to different analytical needs. The technical specifications of the electronic pressure control (EPC) component are as follows:

[0064] A. Control accuracy not less than 0.01 psi; automatic temperature and pressure compensation.

[0065] B. Retention time reproducibility: < 0.008%

[0066] C. Peak area reproducibility: < 1% RSD.

[0067] (2) Column oven 8: The column oven 8 is located on the main unit of the gas chromatograph and is used to stably control the operating temperature of the chromatographic column 10 to ensure the separation effect of the chromatographic column 10. The technical specifications of the component are as follows:

[0068] A. Temperature range: Low temperature: 10℃ above room temperature; High temperature: ≥420℃

[0069] B. Temperature setting: ≤0.1℃;

[0070] C. Heating rate: slowest 0.1℃ / min, fastest ≥120℃ / min

[0071] D. Temperature stability: Better than 0.01℃ when the ambient temperature changes by 1℃.

[0072] E. Program warm-up: Stage 20, Platform 21

[0073] F. Maximum running time: 999.99 minutes

[0074] (3) Inlet 9: The inlet 9 is a capillary column split / splitless inlet: located at the top of the gas chromatograph main unit, 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. The technical specifications of the component are:

[0075] A. Maximum operating temperature: 400℃

[0076] B. Electronic parameter settings: pressure, flow rate, and split ratio; maximum split ratio not less than 5000:1.

[0077] C. Pressure setting range: 0-150Psi

[0078] D. Flow rate setting range: N2: 0-600ml / min, H2: 0-500ml / min and above

[0079] (4) Hydrogen flame ionization detector (I, II): Located on the top of the gas chromatograph, it detects and identifies the separated organic components. The technical specifications of the component are as follows:

[0080] A. Maximum operating temperature: 420℃

[0081] B. Limit of detection: 3 pg C / s (dodecane)

[0082] C. Linear dynamic range: ≥107.

[0083] (4) Automatic Liquid Sampler: Installed above the gas chromatograph main unit and connected to the injection port 9. It automates the sample injection process, thereby improving analytical efficiency, reducing injection costs, and enhancing the accuracy and reproducibility of analytical data. The component's technical specifications are as follows:

[0084] A. Same brand as the chromatograph, dual-tower injection.

[0085] B. 15 sample vial positions, excluding wash bottles.

[0086] C. Cross-contamination: less than 10⁻⁴ (using 4 solvents for washing, determining 1% biphenyl in n-hexane).

[0087] When analyzing the complex organic composition of heavy diols, a byproduct of ethylene glycol production from natural gas, the separation of high-boiling-point components is difficult due to the large variety of organic components. Analyzing with a single chromatographic column and a single flame ionization detector makes it challenging. The retention times of the chromatographic peaks are also similar, leading to peak overlap or contiguous peaks. Each analysis requires manual peak processing to obtain analytical data, and the processed data exhibits poor repeatability and a long analysis time. Therefore, based on the existing gas chromatograph, an independent analytical route was added for programmed temperature rise of column 6 via aging chamber 7. After the liquid to be analyzed is automatically injected through injection port 9, it can be delivered to column 10 and column 6 for targeted and rapid heating to the required temperature. Low-boiling-point components are programmed temperature rise of column 10 via the gas chromatograph's built-in column oven 8, with the initial temperature set at 40℃, analyzing only low-boiling-point components with boiling points below 120℃. High-boiling-point components are programmed temperature rise of column 6 via the added aging chamber 7, with the initial temperature set at 120℃, analyzing only high-boiling-point components. This effectively solves the problems of long analysis time and difficulty in separating high-boiling-point components, reduces the operator's workload, decreases analytical errors, and improves the accuracy of analytical data. This avoids the problem of prolonged analysis time caused by reducing the carrier gas flow rate and temperature program when heavy diols contain small amounts of low-boiling-point esters that are close to the boiling points of high-boiling-point substances. It also avoids the situation where the chromatographic peaks of two high-boiling-point components merge or overlap, requiring manual peak accumulation and resulting in poor repeatability and accuracy of analytical data.

[0088] A further improvement includes an ultra-clean gas purifier 2, whose inlet end is connected to nitrogen 1, hydrogen, and the hydrogen in the air pipeline; a first gas supply pipeline is provided between the nitrogen 1 outlet end of the ultra-clean gas purifier 2 and the sample inlet 9; the nitrogen 1 outlet end of the ultra-clean gas purifier 2 is also provided with a second outlet pipeline connected to the hydrogen flame ionization detector 1 3 and the hydrogen flame ionization detector 2 5 respectively, and the nitrogen 1 output from the second outlet pipeline is used as the tail gas for the hydrogen flame ionization detector 1 3 and the hydrogen flame ionization detector 2 5 respectively. The hydrogen outlet end of the ultra-clean gas purifier 2 is also provided with a third outlet pipeline connected to the hydrogen flame ionization detector 1 3 and the hydrogen flame ionization detector 2 5 respectively, and the hydrogen output from the third outlet pipeline is used as the fuel gas for the hydrogen flame ionization detector 1 3 and the hydrogen flame ionization detector 2 5 respectively. The air outlet of the ultra-clean gas purifier 2 is also provided with a fourth air outlet pipeline that is connected to the hydrogen flame ionization detector 3 and the hydrogen flame ionization detector 5 respectively. The air output from the fourth air outlet pipeline is used as the combustion aid for the hydrogen flame ionization detector 3 and the hydrogen flame ionization detector 5 respectively.

[0089] Due to moisture and dust in the gas, without purification, the flame temperature inside the aging chamber 7 will decrease, affecting the heating rate. Simultaneously, condensation may occur inside the detector, corroding circuits or affecting the stability of electronic components. In particular, dust particles may clog detector nozzles or deposit on electrode surfaces, affecting ion collection efficiency and easily leading to high baseline noise and ghost peaks during detection, impacting the accuracy of trace component analysis. Therefore, to address these issues, an ultra-clean gas purifier 2 is added. This purifier effectively removes hydrocarbons and moisture from nitrogen gas 1, as well as moisture and dust from hydrogen and air, providing a stable supply of high-purity nitrogen gas 1, high-purity hydrogen, and clean air to the gas chromatograph. This prevents baseline fluctuations and ghost peaks, improving the accuracy of analytical results, ensuring the heating rate of column 6 within the aging chamber 7 and preventing corrosion of circuits or impact on electronic components inside the detector. It also prevents dust particles from clogging detector nozzles or depositing on electrode surfaces, thus affecting ion collection efficiency.

[0090] A further improvement is that the first chromatographic column 10 is an HP-FFAP gas chromatographic column, and the second chromatographic column 6 is a DB-624 gas chromatographic column, both of which are equipped with multi-stage temperature programs.

[0091] Heavy diols, a byproduct of natural gas-to-ethylene glycol production, are liquid at room temperature. When using two sets of parallel hydrogen flame ionization detectors for gas chromatography analysis, low-boiling-point components are analyzed using an HP-FFAP gas chromatography column, while high-boiling-point components are analyzed using a DB-624 gas chromatography column. A multi-stage temperature program is also set, allowing the sample to be directly injected through the autosampler inlet 9. The two gas chromatography columns then perform targeted separation of the analytes, enabling the acquisition of all analytical data with a single injection, effectively shortening the analysis time. Example

[0092] The second objective of this application is achieved through the following technical solution:

[0093] A method for analyzing heavy diols, a byproduct of ethylene glycol production from natural gas, comprising the following steps: using a heavy diol analysis device for ethylene glycol production from natural gas, the method includes the following steps for analyzing the heavy diols using the analysis device:

[0094] S1. Set the gas chromatograph parameters as follows:

[0095] The injection volume at inlet 9 is 0.4 μL; the number of solvent washes before injection is 3; the number of sample washes before injection is 3; the number of solvent washes after injection is 4; the split ratio is 80±5:1; the vaporization chamber temperature is 300℃; and the purging flow rate is 3.0 mL / min.

[0096] Column 10HP-FFAP: 50.0m × 0.32mm × 0.50μm, flow rate 1.31mL / min;

[0097] Column 2 6DB-624: 60m × 0.25mm × 1.40µm, flow rate 1.53mL / min;

[0098] The temperature of the two detectors was 300.0℃, the flow rate of the tail gas was 30 mL / min, the flow rate of hydrogen was 40 mL / min, and the flow rate of air was 400 mL / min;

[0099] S2. Establish a standard curve for heavy diols: After preparing single standards and mixed standards, run a gas chromatograph. Perform qualitative analysis of the analytes in heavy diols by single standard determination; perform quantitative analysis of the organic components in heavy diols by mixed standard determination; and establish a mixed standard quantitative calibration curve for heavy diols.

[0100] A new analytical method for heavy diols has been established, which includes multiple systems. The detailed parameters of the main systems are as follows:

[0101] (1) Gas system

[0102] The sample injection system uses nitrogen as the carrier gas, hydrogen as the fuel gas, and air as the combustion-supporting gas, with a hydrogen:air ratio of 1:10. The make-up gas flow rate is 30 mL / min; the hydrogen flow rate is 40 mL / min; and the air flow rate is 400 mL / min. The system includes...

[0103] (2) The separation system includes

[0104] Column 10: HP-FFAP: 50.0m × 0.32mm × 0.50μm; Flow rate: 1.31mL / min; Temperature program: Initial temperature 40℃, hold for 2min; First-order temperature ramp rate 10℃ / min, ramp to 140℃, hold for 6min, analysis time 18min;

[0105] Column 26: DB-624: 60m × 0.25mm × 1.40um; Flow rate: 1.53mL / min; Temperature program: Initial temperature 120℃, hold for 2min; First-order temperature ramp rate 15℃ / min, ramp to 180℃, hold for 6min; Second-order temperature ramp rate 10℃ / min, ramp to 220℃, hold for 2min; Analysis time: 18min;

[0106] (3) The data processing system includes

[0107] The system features high-precision QA / QC control, supporting automatic calculation of methodological parameters such as noise, drift, signal-to-noise ratio, LOD, LOQ, precision, and recovery. It also includes instrument system inspection and user safety management functions. Detailed parameters during the system's process are as follows: injection volume: 0.4 μL; pre-injection solvent washes: 3; pre-injection sample washes: 3; post-injection solvent washes: 4; split ratio: 80:1; vaporization chamber temperature: 300℃; purge flow rate: 3.0 mL / min; column oven temperature program: initial temperature 40℃, hold for 2 min; first-order ramp rate 10℃ / min, ramping to 140℃. The analysis time was 18 min; the temperature program for the chromatographic aging chamber 7 was as follows: initial temperature 120℃, hold for 2 min; first-stage heating rate 15℃ / min, increase to 180℃, hold for 6 min; second-stage heating rate 10℃ / min, increase to 220℃, hold for 2 min; analysis time: 18 min; detector: flame ionization detector, temperature 300℃; nitrogen 1 was used as carrier gas, hydrogen as fuel gas, and air as combustion-supporting gas, with a hydrogen:air ratio of 1:10; make-up gas flow rate: 30 mL / min; hydrogen flow rate: 40 mL / min; air flow rate: 400 mL / min.

[0108] S3. Sample collection and processing: Samples are collected on-site using glass reagent bottles with screw caps.

[0109] S4. Sample analysis: The system generates component chromatograms.

[0110] When using the new method for analysis, because continuous automated injection analysis is employed, all analyte data can be obtained with a single injection. This simplifies operation, reduces employee workload, minimizes analytical errors, and improves the accuracy of analytical data. Multiple solvent washes before and after injection remove residues from the previous sample, ensuring the automated injection needle remains clean and does not contaminate the sample to be analyzed. In particular, four solvent washes after injection effectively prevent incomplete removal of sample residues. A split ratio that is too small can lead to peak merging or overlap, while a split ratio that is too large results in poor peak shape, small peak area, and unresponsive trace components. A split ratio of 75–85:1 produces better peak shape, especially at a split ratio of 80:1.

[0111] A further improvement is made to the single standard configuration step in step S2, which includes:

[0112] A1. Take small amounts of methyl acetal, 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-propanediol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, and triethylene glycol into 23 chromatographic vials.

[0113] A2. Add an appropriate amount of ethylene glycol to each vial and shake well. Place each single standard in the sample tray of the gas chromatograph's autosampler.

[0114] A3. The analytical method for heavy diols in step S2 is used to qualitatively analyze 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-propanediol, 1,2-butanediol, 2,3-butanediol, γ-butyrolactone, dimethyl oxalate, 1,4-butanediol, diethylene glycol, ethylene carbonate, 1,2-hexanediol, and triethylene glycol to determine the retention time of each component; the mass ratio of the single standard component to ethylene glycol in the 23 chromatographic injection vials is 1:10.

[0115] By analyzing 23 chromatographic vials in the sample tray of a gas chromatograph's autosampler using a method for analyzing heavy diols, qualitative analysis of the analytes in heavy diols can be achieved. The mass ratio of the single standard component to ethylene glycol in the 23 vials is 1:10; within this ratio range, the retention times of the chromatographic peaks of the analyte, ethylene glycol, and other impurities in the single standard can be effectively distinguished. This solves the problem of discrepancies between the retention times of each component and the actual sample.

[0116] A further improvement is made to the step S2, which involves preparing a mixed standard of heavy diol samples, including:

[0117] B1. Using a 100,000 ppm electronic balance, weigh the following components sequentially: ethylene carbonate, dimethyl oxalate, methyl acetal, methyl formate, methanol, ethanol, dimethyl carbonate, n-propanol, sec-butanol, isobutanol, n-butanol, ethylene glycol methyl ether, methyl glycolate, 2-pentanol, 1,2-propanediol, γ-butyrolactone, 1,4-butanediol, 1,2-hexanediol, 2,3-butanediol, and 1,2-butanediol, approximately 0.35000 g ± 10% of diethylene glycol and triethylene glycol, and approximately 2.10000 g ± 10% of ethylene glycol into a 10 mL clamp-top bottle and shake well. Detailed parameters for the mixed standard are shown in Table 1.

[0118] B2. Transfer the mixed standard into the chromatographic injection vial and place it in the sample tray of the gas chromatograph's autosampler.

[0119] B3. Run the analytical method for heavy diols in step S2 to perform quantitative analysis on the sample, and use the calibration area normalization method to establish a calibration curve for heavy diol analysis.

[0120] Table 1: Standard Samples of Heavy Diols

[0121] Mixed standards should be used as soon as possible after preparation, to avoid alcohol-ester exchange reactions among the components in the mixed standard, which would affect the true concentration of each component in the mixed standard sample. Chromatographic grade or analytical standard dimethyl oxalate dissolves slowly, therefore, ultrasonic dissolution is accelerated in an ultrasonic cleaner.

[0122] By placing the mixed standard chromatographic vial into the sample tray of the gas chromatograph's autosampler for analysis of heavy diols, quantitative analysis of the organic components in heavy diols can be achieved, thus establishing a mixed standard quantitative calibration curve for heavy diols. Using the calibration area normalization method, the established standard working curve directly yields the ratio of peak area to content for each analyte. This allows for direct determination of the specific content based on the peak area when analyzing actual samples, significantly shortening the analysis time and avoiding the problem of peak overlap or connection at high-boiling-point components, which necessitates manual peak accumulation. This results in high repeatability and accuracy of the analytical data.

[0123] A further improvement is made to the sample analysis step in step S4, which includes:

[0124] C1. Take 1.0±0.1g of heavy diol sample into a chromatographic vial and place it in the sample tray of the gas chromatograph's autosampler;

[0125] C2. Run the analytical method for heavy diols in step S2;

[0126] C3. After the heavy diol analysis method is completed, a quantitative calibration curve is loaded to correct the chromatogram, and the contents of organic components and water in the heavy diol can be obtained.

[0127] Approximately 1.0 g of heavy diol sample was placed in a chromatographic vial and then placed in the sample tray of the gas chromatograph's autosampler. The analytical method for heavy diols in step S2 was run. The sample was passed through column 10, flame ionization detector 3, and workstation 4 to obtain chromatograms of the components with boiling points below 120℃. The sample was then passed through column 6, flame ionization detector 5, and workstation 4 to obtain chromatograms of the components with boiling points above 120℃.

[0128] After the heavy diol analysis method is completed, the quantitative calibration curve from step 3 is loaded to correct the chromatogram, and all components in the heavy diol can be obtained.

[0129] pass Figure 2 and Figure 3 It can be seen that the heavy diol analysis method established according to the present invention is stable in operation, with high data repeatability and high resolution; it can achieve the effect of obtaining the content of all components with a single injection.

[0130] The above embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of protection of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application shall fall within the scope of protection claimed by this application.

Claims

1. An analysis device for heavy glycols byproduct of natural gas to ethylene glycol, comprising a gas chromatograph, the gas chromatograph comprising a sample inlet (9), a chromatographic column I (10), a workstation (4), a column oven (8) and a hydrogen flame ionization detector I (3), both ends of the chromatographic column I (10) are connected with the sample inlet (9) and the inlet of the hydrogen flame ionization detector I (3) respectively, and the outlet of the hydrogen flame ionization detector I (3) is connected with the workstation (4), characterized in that: Between the injection port (9) and the workstation (4), a second chromatographic column (6), a second flame ionization detector (5), and an aging chamber (7) are also provided. The two ends of the second chromatographic column (6) are respectively connected to the injection port (9) and the inlet of the second flame ionization detector (5). The outlet of the second flame ionization detector (5) is connected to the workstation (4). The programmed temperature rise process of the first chromatographic column (10) is completed in the column oven (8), and the programmed temperature rise process of the second chromatographic column (6) is completed in the aging chamber (7).

2. The apparatus for analyzing heavy diols byproduct of ethylene glycol production from natural gas according to claim 1, characterized in that: The first chromatographic column (10) is an HP-FFAP gas chromatographic column, and the second chromatographic column (6) is a DB-624 gas chromatographic column, both of which are equipped with multi-stage temperature programs.

3. The apparatus for analyzing heavy diols byproduct of ethylene glycol production from natural gas according to claim 1, characterized in that: It also includes an ultra-clean gas purifier (2) whose inlet end is connected to nitrogen, hydrogen and air pipelines.

4. The apparatus for analyzing heavy diols byproduct of natural gas to ethylene glycol of claim 3, wherein: The nitrogen (1) outlet of the ultra-clean gas purifier (2) is connected to the sample inlet (9), the first hydrogen flame ionization detector (3), and the second hydrogen flame ionization detector (5), respectively.

5. The apparatus for analyzing heavy diols byproduct of natural gas to ethylene glycol of claim 3, wherein: The hydrogen outlet of the ultra-clean gas purifier (2) is connected to the hydrogen flame ionization detector one (3) and the hydrogen flame ionization detector two (5), respectively.

6. The apparatus for analyzing heavy diols byproduct of ethylene glycol production from natural gas according to claim 3, characterized in that: The air outlet of the ultra-clean gas purifier (2) is connected to the hydrogen flame ionization detector one (3) and the hydrogen flame ionization detector two (5), respectively.

7. The apparatus of claim 1, wherein: The aging chamber (7) is 480mm long, 750mm wide, and 520mm high; the maximum operating temperature is 400℃; the temperature control accuracy is ±0.1℃; the power is 2kw; and the voltage is 220V.

8. The apparatus of claim 1, wherein: The injection port (9) adopts a capillary column split / splitless injection port.

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