The application of ramming coking technology in the urban gas industry

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The application of ramming coking technology in the urban gas industry. Keywords: coal resources, ramming coking, gas production. Chinese Library Classification Numbers: TU996, TQ522.15. In China’s gas industry, the process of coal dry distillation for gas production remains the primary method used by many gas plants to generate gas. Due to the uneven pace of economic development in different regions, large-volume coke ovens with low heat consumption and high efficiency are difficult to be adopted by gas plants in medium and small cities because of their high investment costs. As a result, medium and small coke ovens with lower investment costs and high heat consumption continue to be used, retaining their unique practical value. In recent years, with the continuous expansion of the gas market, meeting the urban gas supply needs is no longer the only goal for gas plants. Reducing coke costs, improving coke quality, ensuring coke sales, and guaranteeing a steady supply of urban gas have become important strategies for many gas plants in order to survive. Due to the limitations in the types of coking coal available in our country, along with the specific supply and demand dynamics for high-quality coking coal among key enterprises in various regions, although there have been significant changes in the coal supply channels, these factors still pose new challenges to the coal usage patterns and coking costs of gas plants in medium and small cities. How to make full use of the local coal resources to produce high-quality coke, meet the demand for gas supply, and reduce gas production costs has become an important issue that gas plants in medium and small cities urgently need to address. This article presents several views on the coking coal resources in East China, as well as the application of rammed coking technology in the urban gas industry to address the aforementioned issues. 1 Impact of raw coal on coke quality Although China is rich in coal resources, 63.3% of them are non-coking coals, while only 36.2% are coking coals. On the other hand, the distribution of coal types is highly uneven; the coal types used for coking in the East China region account for only about 6.73% of the country’s total coking coal reserves. Regarding the coal resources in the entire region, bituminous coal (1/3 coking coal) accounts for 78.10%, fat coal accounts for 12.26%, lean coal accounts for 1.93%, coking coal accounts for 2.57%, and other types of coal account for 5.14%. Among them, fat coal is mainly produced in Shandong, while coking coal and 1/3 coking coal are mostly produced in the Lianghuai region. In the use of coal for coking, due to the specific requirements for high-quality coking coal from companies such as Shanghai Baosteel, Anhui Magang, and Shanghai Coking Plant, as well as the increasing scarcity and high prices of such coal, it has become even more difficult for medium and small-scale gas plants that use the top-charging coking process to select and obtain coking coal. 　　As is well known, coking coal has a significant impact on the quality of the coke produced. Generally, medium and small coal gas plants use coke ovens with small carbonization chambers; it is difficult to achieve an ideal density for the coal cakes using the top-charging coking process. Coupled with limitations in the types of coal used for coking, it is not possible to produce satisfactory metallurgical coke. As a result, large quantities of coke remain unsold and accumulate, preventing the plants from maintaining proper capital flow. They are forced to reduce their production volume in search of sales channels, which ultimately affects the supply of gas for production. Therefore, making full use of the local coal resources, selecting an ideal coking process to produce high-quality coke, and ensuring a stable supply of gas for cities has become the consensus among many gas plants. 2 Application and Development of Ramming Coking Technology In recent years, the ramming coking process has gradually matured, and the equipment used for this process has been continuously improved. The effective treatment of raw gas generated during the side-loading of coal offers promising prospects for addressing the issue of rational resource utilization and the production of high-quality coke. 　　The ramming coking process can increase the bulk density of the coal fed into the furnace and improve its coking properties, allowing a larger proportion of bituminous coal and weakly caking coals to be used in coal blending for coking, while still yielding satisfactory coke quality. 　　In the coking theory, colloids are the bonding components that facilitate the combination of coal particles; the bonding process of particulate coal occurs at the contact interfaces between these particles. An increase in the bulk density of the coal fed into the furnace enhances the bonding effect of the gelatinous substances, and during pyrolysis it improves the contact between the softened coal particles. This compensates for the loss of contact between coal particles that usually occurs due to uneven flow of the gelatinous substances. Therefore, the structural strength of coke increases as the bulk density of the coal fed into the furnace increases; it is evident that increasing the bulk density of the coal fed into the furnace is one effective way to improve coke quality. The use of the ramming coking technology in areas such as Huainan, Zhenjiang, Fushun, and Beitai in our country has yielded significant results. In particular, in Huainan, coking is achieved using only 1/3 bituminous coal through ramming, and coke that meets the requirements of medium-sized blast furnaces can be produced. Zhenjiang, on the other hand, uses a coal blending method combined with ramming coking to produce high-quality casting coke. These achievements have drawn considerable attention from the coking industry to the application and development of ramming coking technology, giving it great practical significance. 　　(1) It effectively solved the problem of producing high-quality coke from coal with low caking strength, thereby ensuring the normal operation of gas plants. 　　(2) By making full use of the local coal resources, long-distance transportation of coal is reduced, thereby lowering the costs associated with its transport ； At the same time, as the grade of coke improves, its price rises, effectively reducing the cost of gas production. 　　(3) It allows for a significant increase in the proportion of fat-coal and 1/3 coking coal, thereby expanding the effective means for regulating gas production levels. 　　(4) For medium and small coke ovens, due to their smaller carbonization chamber volume, the length-to-width-to-height ratio of the coal cake offers greater advantages for its shaping and proper loading into the oven. 　　(5) Various high-quality cokes can be produced to meet the different demands of the coke market. 　　In summary, the use of ramming coking technology for the development of city gas holds significant value in terms of making rational use of local coal resources, ensuring a stable supply of city gas, managing peak demand, and meeting the market demands for coke. It represents an effective approach and offers great prospects for the development of the gas industry in small and medium-sized cities.