The main advantage of Online Gas Chromatographs technology is its excellent selectivity. By using different chromatography columns and detector techniques, online chromatography instruments achieve high sensitivity and analytical precision. They also feature multi-point and multi-component simultaneous detection, making them widely used in industries such as petroleum refining, chemical processing, and metallurgy.
Applications of Online Gas Chromatographs in the Petrochemical Industry
Online gas chromatography has become the most important analytical method for online analysis in the petrochemical industry. With the development of petrochemical processes and the application of advanced control and real-time optimization technologies, online chromatography analysis information has become an indispensable control parameter. Additionally, the importance of online gas chromatography in petrochemical industries is growing due to increasing demands for environmental protection, safety, high quality, energy saving, and cost reduction. The number of online gas chromatographs used in petrochemical enterprises, especially those with similar scale and processes, is also increasing. The most significant application in the petrochemical industry is in ethylene units, with some units using nearly 100 online gas chromatographs. Ethylene plants are the leading units in petrochemical production, characterized by large scale, long processes, complex process control, and high reliability and safety requirements, placing high demands on the stability of online chromatographs.
In the ethylene process analysis setup, the most frequently used and most important instruments are online gas chromatographs. We set up online gas chromatographs at various measuring points, such as the cracking furnace distillate, alkaline wash tower inlet and outlet, hydrogenation reactors, de-methanation tower, de-ethanation tower, de-propanation tower, de-butanation tower, C2 and C3 separation towers, and for the purity analysis of ethylene and propylene products, from the feed of light hydrocarbon raw materials to the products of ethylene and propylene. The application points continue to increase. For example, with the introduction of dielectric barrier discharge ionization detectors (DBDID), online gas chromatographs can measure trace components like oxygen and ammonia in ethylene products. Recently, we have applied online gas chromatography to directly measure trace total hydrocarbons (THC) in ethylene plant steam condensates. This method offers a more direct, faster, and accurate approach, overcoming previous drawbacks such as low measurement accuracy and high maintenance costs associated with TOC analyzers.
Applications of Online Gas Chromatographs in the Refining Industry
In the refining industry, online gas chromatographs were previously used primarily in catalytic cracking, gas separation, aromatics and BTX processes, reforming, hydrogen production, hydrogenation, alkylation, and MTBE (Methyl Tert-Butyl Ether) production. With the application of advanced and optimized control technologies, the usage of online gas chromatographs is increasing, especially to replace traditional oil quality instruments for measuring oil product distillation (including dry point, initial distillation point), ice point, flash point, vapor pressure, etc.
During the refining process, critical oil quality indicators like distillation range, Reid vapor pressure (RVP), flash point, ice point, and pour point are important production and product control parameters. The common method for measuring these indicators is by using specialized online oil quality analyzers, such as online full-distillation analyzers, flash point analyzers, and pour point analyzers. We often automate these analyzers and adapt them to online versions of American Society for Testing and Materials (ASTM) laboratory methods for real-time measurement of specific quality indicators. However, these instruments are complex, expensive, have limited analysis parameters, harsh operating conditions, and require high maintenance, resulting in low equipment uptime.
Using gas chromatography to simulate distillation methods (ASTM D3710, ASTM D2887) offers accurate data, fast analysis speed, minimal sample requirements, high automation, and compliance with environmental protection standards. It can provide accurate, timely measurement data for distillation cutting, optimizing process operations, improving product yield, and controlling oil quality in refining. With online gas chromatography, it is also possible to measure RVP, flash point, ice point, and pour point during the process, providing an important technology for improving automation control in refining. This technology has been widely used in foreign refineries, and its application in domestic refineries is just beginning.
Applications of Online Gas Chromatographs in the Chemical Industry
In ammonia synthesis and ammonia processing industries, online gas chromatographs are used to analyze the components of raw gases, conversion gases, and synthesis gases, controlling hydrogen-nitrogen ratios, water-carbon ratios, and ammonia-carbon ratios. With the rapid development of coal chemical processes, online gas chromatography has also found widespread use in industries like coal-based methanol to olefins (MTO). The importance and usage of online gas chromatography in the MTO process is comparable to that in ethylene units in the petrochemical industry. In coal-based ethylene glycol processes, online gas chromatographs are used in various stages, including gasification, transformation, purification, cryogenic separation, hydrogen reactions, and hydrogenation distillation.
| Industry | Application Area | Main Role |
| Petrochemical Industry | Ethylene unit (cracking furnace, separation towers, etc.) | Real-time monitoring of raw materials, cracking products, and gas components to improve production stability and safety |
| Refining Industry | Catalytic cracking, gas separation, aromatics reforming, oil quality control | Replacing traditional oil quality instruments to measure distillation range, flash point, vapor pressure, etc., improving data accuracy |
| Chemical Industry | Ammonia synthesis, coal chemical, coal-based ethylene glycol process | Controlling key parameters like hydrogen-nitrogen ratio, carbon ratio, optimizing processes, and improving product quality |
Conclusion
Online gas chromatographs have extensive applications in the petrochemical, refining, and chemical industries, particularly in process analysis and quality control. Their main advantages include high sensitivity, strong selectivity, and the ability to simultaneously detect multiple points and components.
In the petrochemical industry, online gas chromatography is widely applied in ethylene units to analyze various stages from raw materials to final products, with increasing detection applications.In the refining industry, online gas chromatographs are replacing traditional oil quality instruments to measure distillation ranges, flash points, and other quality indicators, improving data accuracy and analysis efficiency. In the chemical industry, online gas chromatography is used in processes like ammonia synthesis and coal chemical processes for real-time analysis, controlling key parameters and improving production efficiency and product quality. Thus, online gas chromatographs play a crucial role in optimizing production processes, enhancing automation, and reducing costs.
