Technical Specification for Producing Ethylene Glycol from Coking Plant Gas
1Key Takeaways
This standard provides detailed guidelines on the process of producing ethylene glycol from coal gas. It outlines the technical requirements, operational procedures, and safety measures necessary for the efficient and safe implementation of this production method. The document covers key aspects such as raw material pr…
2Expert Interpretation
This article provides an in-depth interpretation of GB/T 47092-2026 "Technical Specification for Ethylene Glycol Production from Coke Oven Gas", covering core contents such as process flow, technical requirements, resource recycling and environmental protection requirements, and providing standardized guidance for the high-value utilization of by-product coal gas in the coking industry.
Background and Technological Evolution Analysis of Standard Development
The release of GB/T 47092—2026 "Technical Specification for Ethylene Glycol Production from Coke Oven Gas" marks a new stage of standardized and regulated development in the resource utilization and high-value utilization of by-product coal gas in my country's coking industry. This standard fills the gap in national technical standards for the production of ethylene glycol from coke oven gas, providing a unified technical standard and evaluation basis for this emerging coal chemical pathway.
From a technological evolution perspective, the utilization of coke oven gas has undergone an upgrade process from simple fuel to synthetic ammonia and methanol, and then to higher-value chemicals (such as ethylene glycol). Ethylene glycol, as an important chemical raw material, is widely used in polyester fibers, antifreeze, and other fields, and market demand continues to grow. Utilizing coke oven gas rich in hydrogen and carbon monoxide to produce ethylene glycol not only realizes "turning waste into treasure" and improves the economic benefits and risk resistance of coking enterprises, but also serves as a key technological path to promote the coupling of steel and chemical industries, achieve a circular economy, and reduce carbon emissions.
Against this backdrop, this standard integrates the engineering practice experience of pioneering enterprises such as Shanxi Jinan Iron and Steel and Jinan Iron and Steel, as well as the technological achievements of research institutions such as the Metallurgical Industry Planning and Research Institute and the Southwest Chemical Research and Design Institute. Its aim is to standardize process flows and ensure production safety, environmental protection, and product quality.
In-depth Interpretation of Core Process Flow and Principles
Chapter 4 of the standard clarifies the core "two-step" process route for producing ethylene glycol from coke oven gas. Its basic principle is: first, the effective components (H₂ and CO) in the coke oven gas are converted and purified through catalytic or non-catalytic conversion to obtain high-purity syngas; then, CO is catalytically coupled with methyl nitrite to form dimethyl oxalate (DMO); finally, dimethyl oxalate undergoes a multi-step hydrogenation reaction with H₂ under the action of a catalyst to ultimately synthesize the target product, ethylene glycol (EG).
The process flow (as shown in Figure 1) mainly includes six systems: a pretreatment system, a gas compression and purification system, a conversion system, a separation and purification system, a dimethyl oxalate synthesis system, and an ethylene glycol synthesis system. This is a typical, technology-intensive chemical process, and the stable operation and index control of each link directly affect the yield and quality of the final product.
| Process System | Core Functions | Key Technical Indicators | Main Equipment/Methods |
|---|---|---|---|
| Pretreatment System | Crude Removal of Tar, Naphthalene, and Particulate Matter | Tar ≤10 mg/m³, Naphthalene ≤30 mg/m³ | Fixed Bed Adsorption, Fiber Bed Washing |
| Compression Purification System | Pressurized, Deep Purification of Impurities | Tar, Naphthalene ≤1 mg/m³, Ammonia ≤10 mg/m³ | Two-Stage Compression, Adsorption Method |
| Conversion System | Adjust H₂/CO ratio to convert CH₄ | Outlet CH₄ ≤ 0.6% (catalytic) or 0.3% (non-catalytic) | Conversion furnace (catalytic/non-catalytic) |
| Separation and Purification System | Remove CO₂, sulfur, and water; separate H₂/CO | CO purity ≥ 99%, H₂ purity ≥ 99.9% | Low-temperature methanol washing, molecular sieve, cryogenic/PSA |
| DMO Synthesis System | CO coupling to synthesize dimethyl oxalate | Total conversion rate ≥ 99%, purity ≥ 99% | Coupling reactor, distillation column |
| EG Synthesis System | DMO Hydrogenation to Ethylene Glycol | Total Conversion Rate ≥ 99% | Hydrogenation Reactor, Distillation Column |
Key Technical Requirements and Index Analysis
5.1 Pretreatment and Compression Purification System
Coke oven gas has a complex composition, containing various impurities such as tar, benzene, naphthalene, ammonia, and sulfides. These impurities are "poisons" for subsequent catalysts and must be effectively removed at the front end. The standard stipulates that after pretreatment, the tar content ≤ 10 mg/m³, particulate matter ≤ 5 mg/m³, and naphthalene ≤ 30 mg/m³. After two stages of compression (to 2.0-4.0 MPa) and an intermediate deep purification unit, the indicators are even more stringent: tar, naphthalene, and particulate matter must all be ≤ 1 mg/m³, and ammonia ≤ 10 mg/m³. This requires companies to select highly efficient purification technologies and equipment, such as composite adsorbents and high-efficiency filters, to ensure the cleanliness of the raw gas entering the conversion section. 5.3 Conversion System: Comparison of Catalytic and Non-Catalytic Routes The purpose of the conversion system is to partially oxidize hydrocarbons such as methane in coke oven gas, adjust the H₂/CO ratio in the syngas, and reduce the residual methane content to meet the requirements of subsequent synthesis. The standard provides two technical routes: catalytic conversion and non-catalytic conversion, which companies can choose according to their own conditions.
| Comparison Dimensions | Catalyzed Conversion | Non-Catalyzed Conversion |
|---|---|---|
| Reaction Temperature | Inlet 610-660℃, Outlet ~960℃ | Outlet ~1200℃ |
| Core Requirements | Conversion water-to-gas ratio >0.9, steam salinity <3 mg/m³ | Extremely high requirements for oxygen purity and mixing uniformity |
| Outlet Methane Control | ≤0.6% (volume fraction) | ≤0.3% (volume fraction) |
| Technical Characteristics | The reaction is mild and has relatively low energy consumption, but requires the use and regular replacement of nickel-based catalysts | High reaction temperature, no catalyst required, but has stringent requirements for refractory materials, equipment materials, and control |
| Applicable Scenarios | Suitable for enterprises sensitive to operating costs and with catalyst management capabilities | Suitable for enterprises that wish to avoid catalyst investment and replacement and have experience in high-temperature operation |
5.4 Separation and Purification System: “Refinement” of Syngas
This is crucial for obtaining qualified syngas. The standard recommends using a mature low-temperature methanol wash process to remove CO₂ and sulfides (total sulfur ≤ 0.14 mg/m³), and molecular sieve dehydration (water content ≤ 0.8 mg/m³).
For the separation of carbon monoxide and hydrogen, the standard provides options for cryogenic separation or pressure swing adsorption (PSA). Cryogenic separation yields products with higher purity (CO ≥ 99%) and higher recovery rates, but requires higher investment and energy consumption; PSA requires lower investment and is more flexible in operation, but the product purity or recovery rate may be slightly lower. Enterprises need to conduct a techno-economic comparison. The standard sets forth clear requirements for the purity of the product gas (see Tables 3 and 4), which is a prerequisite for ensuring the long-term stable operation and high selectivity of the subsequent DMO and EG synthesis catalysts.
5.5 & 5.6 Synthesis System: From DMO to EG
Dimethyl oxalate (DMO) synthesis is a CO coupling reaction, and ethylene glycol (EG) synthesis is a DMO hydrogenation reaction. The standard requires that the total conversion rate of both steps be no less than 99%, and sets requirements for the purity of the intermediate product DMO and the final product EG (DMO ≥ 99%, EG conforming to GB/T4649).
This involves a comprehensive test of catalyst performance, reactor design, process condition control (temperature, pressure, space velocity), and product distillation technology. Highly efficient palladium-based and copper-based catalysts are the core components of these two steps, respectively.
Application Case Insights: A company using this route improved CO conversion from 98.5% to 99.2% and extended catalyst life by approximately 15% by optimizing the gas distributor in the DMO synthesis reactor. Simultaneously, the introduction of thermal coupling technology in the EG distillation section significantly reduced steam consumption. This demonstrates that continuous technological optimization, while meeting the basic requirements of the standard, is key to improving the project's economic viability.
Resource Recycling, Environmental Requirements, and Monitoring
Chapter 6 of the standard emphasizes the concepts of circular economy and green production.
The standard requires that process water (demineralized water, circulating water) comply with the relevant national standards (GB/T1576, GB/T50050) to achieve cascade utilization and conservation of water resources. Regarding pollutant emissions and solid waste (such as spent catalysts and adsorbents) disposal, the standard clarifies the minimum requirements that must be met by referencing mandatory environmental protection standards such as GB18597 and GB18599, requiring enterprises to construct complete environmental protection facilities. Chapter 7 specifies comprehensive monitoring and testing methods. For coal gas components, GB/T28901 (gas chromatography) is referenced; for impurities (sulfur, tar, naphthalene, etc.), GB/T12208 is referenced; for trace moisture, four optional methods from the GB/T5832 series (electrolysis, dew point method, cavity ring-down spectroscopy, and quartz crystal oscillation method) are provided, allowing enterprises to choose according to their accuracy and cost requirements. Establishing a standardized and accurate testing system is the foundation for production process control, quality assurance, and environmental compliance.
Operation, Maintenance and Implementation Recommendations
8.1 Management System and Personnel Support
The coke oven gas to ethylene glycol production plant is a large-scale, continuous, and highly automated chemical plant. The standard requires the establishment of sound management systems and operating procedures (8.1.1), and the establishment of a dedicated management department (8.1.2). Operators must undergo rigorous professional training (8.2.1), and must not only understand the process but also possess safety, environmental protection, and emergency response capabilities.
8.3 Maintenance Strategy
The standard emphasizes preventative maintenance (8.3.1).
Enterprises should develop detailed maintenance plans, paying particular attention to the following key equipment: compressors, converters, cryogenic methanol washing tower systems, reactors, and various pumps and valves. Regular inspection, recording, and analysis of operating data are fundamental to achieving safe, stable, long-term, full-capacity, and high-quality operation of the plant.
Implementation Recommendations for Enterprises
- Preliminary Design and Selection: During the project design phase, this standard should be used as a benchmark for process package selection, equipment selection, and plant design to ensure inherent compliance.
- Catalyst Management: Establish a full lifecycle management system for catalysts, including procurement, acceptance, loading, reduction, use, monitoring, and replacement.
- Process Optimization and Intelligent Control: On the basis of meeting standards, actively apply advanced process control (APC), real-time optimization (RTO), and other information technologies to optimize operating parameters and reduce material and energy consumption.
- Industry Chain Collaboration: Strengthen collaboration with upstream coking and downstream polyester industries to stabilize raw material supply, expand product markets, and enhance overall competitiveness.
- Follow Standard Dynamics: This standard is being released for the first time and may be revised in the future as technology advances. Enterprises should continuously monitor relevant national policies, environmental standards, and industry technology dynamics to maintain technological advancement and compliance.
In conclusion, the promulgation of GB/T 47092—2026 lays the technological foundation for the healthy development of the coke oven gas-to-ethylene glycol industry. Enterprises should thoroughly study and strictly implement this standard, using it as the fundamental basis for technical management, production operation, and quality control, thereby achieving sustainable and high-quality development under fierce market competition and stringent environmental requirements.