**Technology Awards: Reports on Achievements in Chemical Equipment ③ Large Coke Ovens Enable Cleaner and More Efficient Coke Production

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**Report on Achievements in Chemical Equipment for Science and Technology Awards ③: Large Coking Ovens for Cleaner and More Efficient Coking. Author/Source: China Chemical Industry News. Date: February 20, 2019. Clicks: 6. In the evaluation of the **Science and Technology Awards in 2018, the project “Development and Application of Clean and Efficient Coking Technologies and Equipment,” led by MCC Coking Engineering Co., Ltd. and jointly carried out by Beijing University of Science and Technology and Anshan Iron and Steel Group Corporation, made it through all rounds of evaluation and won the **First Prize for Scientific and Technological Progress. This project aims to address the key issues related to clean and efficient production in the coking industry, playing an important role in supporting the integrated, green, and high-quality development of China’s coking sector. According to data released by the Ministry of Science and Technology, thanks to the achievements of this project, the research and development entities have generated direct sales revenues of 37 billion yuan and profits of 4 billion yuan over the past three years. Meanwhile, the industry concentration in China’s coking sector has increased by 3.8 times, pollutant emissions have been reduced by 12%, consumption of high-quality resources has decreased by 7.5%, and energy consumption has fallen by 4%. The project’s technology features many innovative highlights. 　　No longer subject to others’ control. Coking is an important industry that underpins metallurgy, the chemical industry, and machinery manufacturing; however, due to its high consumption and high emissions, there has been increasing pressure to transform and upgrade it in recent years. Wang Mingdeng, deputy chief engineer at MCC Coking, said that the enlargement of coke ovens is one of the key approaches for the transformation and upgrading of the coking industry; only by using larger coke ovens can large-scale, centralized production be achieved, thereby reaching the goals of cleanliness and efficiency. 　　According to statistics from the China Coking Industry Association, at the beginning of the 20th century, most coking ovens in China were of small to medium size; large-scale coking ovens accounted for only about 15% of the total national coke production capacity, and the height of these ovens did not exceed 6 meters. By 2008, China still had to import 7-meter-high coke ovens from abroad. By the 1980s, Germany and Japan had already begun building a large number of coke ovens with heights exceeding 7 meters. 　　Developing a 7-meter-scale coke oven is not simply a matter of creating a larger furnace; the key lies in understanding the mechanisms of heat transfer, combustion, flow, and high-temperature carbonization of coal within the oven, as well as addressing how super-large carbonization chambers can provide adequate and uniform heating to the coal material and enable rapid and even coke production. The larger the size of the coke oven, the more difficult it is to effectively control its internal temperature. If the local flame temperature in the coke oven is too high, not only does energy consumption increase, but large amounts of nitrogen oxides are also generated, making it impossible to reduce emissions at the source; in addition, the oven structure may even be damaged. If the temperature is too low or uneven, crude coke will form, which prevents the maintenance of production quality. 　　To this end, MCC Coking & Refractory, in collaboration with the University of Science and Technology Beijing and Anshan Iron and Steel Group, and relying on the key project \"Development of New Generation Clean and Efficient Coking Processes and Equipment\" under the Ministry of Science and Technology’s \"863\" program, started work on theoretical research, technology development, and equipment design. After more than 10 years of joint efforts, significant scientific and technological achievements have been made in areas such as clean and efficient coking processes, core equipment, and intelligent production. Starting from the mechanism of nitrogen oxide formation, the R&D team developed a mathematical model for coke oven production. By using continuous-process and multi-unit coupling simulations, they guided the structural design of the ovens; as a result, the designed coke ovens achieved full scalability and cleaner operation. 　　Today, China’s coking industry is no longer at the mercy of others; it has also succeeded in exporting its technology and equipment overseas. To date, the achievements of this project have been applied in series across 47 projects at home and abroad, making it the dominant technology in the field of clean and efficient coking. It holds a 96% market share in China’s large-scale coke oven market; moreover, the technology and equipment developed have been exported to overseas markets, accounting for 60% of new large-scale coke oven projects abroad. 　　No more high levels of pollution emissions. Yu Zhendong, chairman of MCC Coking Refractories, pointed out that nitrogen oxides, particulate matter, and sulfur dioxide are the pollutants most difficult to control in coking production, which is why the coking industry was previously considered by outsiders to be one of those industries prone to causing environmental degradation. Greening, efficiency, and intelligence are the main trends in the future development of coking technology. 　　However, due to the complex formation mechanisms, controlling nitrogen oxides in coke ovens is a global challenge. Calibration data from conventional coke ovens show that when heating with coke oven gas, the average nitrogen oxide content in the exhaust gases is above 1000 milligrams per cubic meter, while when using gas with a lower calorific value, this value ranges from 450 to 650 milligrams per cubic meter. According to Wang Mingdeng, in 2008 China introduced 7.63-meter coke ovens using German technology. At that time, the most advanced coking technologies in the international coke industry could reduce nitrogen oxide emissions to below 350 milligrams per cubic meter, with furnace capacities reaching over 2 million tons per year. However, with China’s own technology, nitrogen oxide emissions could only be kept at levels between 600 and 1,000 milligrams per cubic meter, and the production capacity of these furnaces was only 3/4 that of those in Germany. 　　To address this challenge, the project’s R&D team started with combustion theory and simulation analysis to study the mechanism of nitrogen oxide formation during diffusive combustion in the narrow flues of coke ovens. By integrating the entire structure of the carbonization chamber, combustion chamber, and regenerator, they developed simulation methods for unsteady processes such as heat and mass transfer, combustion, flow, and high-temperature carbonization of coal within complex structural systems. They proposed a theory for controlled staged supply of low-nitrogen combustion, and invented a technology for uniform heating through such controlled staged supply, which reduced the nitrogen oxide content in flue gases by over 50%, thus solving the global problem of reducing nitrogen oxides at their source in coke ovens. 　　It is reported that the outcomes of this project not only provide solutions for low-nitrogen emissions and clean production in China’s coking industry, but also offer applicable technologies for the newly established **standard ‘Emission Standards for Pollutants in the Coking Chemical Industry (GB16171-2012)’. 　　No more high consumption and low efficiency. In line with China’s principle of efficient utilization of coal resources, coking ovens must be able to minimize the use of coal while enhancing production efficiency. Industry experts believe that to achieve efficient production in ultra-large capacity coke ovens, two major issues must first be resolved: first, how to ensure uniform heating of more than 40 tons of coal material in a 7-meter-high carbonization chamber under partitioned heating conditions; and second, how to prevent the segmented heating technique used to reduce nitrogen oxide levels from having an adverse effect on the smooth operation of the oven. 　　Wang Mingdeng said that as the size of coke ovens increases, it becomes extremely difficult to provide uniform and adequate heating to the coal material; precise control over the high-temperature flames in the more than 2,000 heating channels can only be achieved through the oven’s own structure. Furthermore, if an emphasis is placed solely on increasing production intensity by **raising the heat supply, combined with the newly developed segmented heating technology, it can easily lead to problems such as excessively high temperatures in the furnace roof area and poor operational continuity. 　　To this end, the R&D team, based on the caking, binding, and shrinkage properties of coking coal in China, developed a new type of perforated structure that allows for segmented heat supply within a 7-meter-high heating channel to meet the requirements for coal coking. Through a unique technique for adjusting vertical temperature gradients, they achieved uniform heating in the vertical direction as well as effective control of the top temperature of the furnace, thereby completely solving the global problem of excessive temperatures in the upper part of large-scale coke ovens. This approach also significantly reduced the amount of high-quality coking coal required. To achieve uniform heating in the longitudinal direction, the R&D team divided the 18-meter-long walls of the carbonization chamber into 18 heating units, corresponding to the heat requirements during the coking process of the coal, thereby enabling precise regional heating. They also developed a technology for coordinated distribution of airflow at the bottom of the furnace, and invented a longitudinally oriented airflow distribution structure that allows for simultaneous adjustment from both the top and bottom. 　　Compared with the technologies previously introduced in our country, this new technology can reduce the usage of high-quality coking coal by more than 7.5%, ensures uniform heating in both the longitudinal and vertical directions of the coke oven, and also significantly reduces energy consumption. At the same time, the R&D team has also developed key unmanned equipment such as remote switching of coke oven heating gas types and remote operation of high-temperature gas collection system devices, which can reduce the labor force required for coke production by 30% and enable the intelligentization of coke production processes.