Thread Content
Creating a new model for coal utilization via “pyrolysis+” – A look at the key technologies and applications for the clean and efficient use of low-grade coal. Author/Source: Sinochem News Network. Date: June 22, 2022. Clicks: 13. A few days ago, the People’s Government of Shaanxi Province announced the list of winners of the 2021 Shaanxi Provincial Science and Technology Awards; many achievements in the field of petroleum and chemicals were recognized among them, with three outstanding technical achievements winning first prizes in the categories of Technical Invention Award and Scientific and Technological Progress Award. To this end, starting today, a series of reports titled \"Display of Awards Won in the Shaanxi Science and Technology Awards – First Prize\" will be published, providing an analysis of the innovative concepts behind these three technologies as well as their contributions to the industry, for the reference of readers. Among the projects that won awards in Shaanxi Province’s science and technology awards in 2021, the project titled “Key Technologies for the Clean and Efficient Utilization of Low-Rank Coal on a Differential Basis and Their Applications”, developed jointly by Shaanxi Coal and Chemical Industry Group Co., Ltd., Beijing Guodian Futong Technology Development Co., Ltd., Shenmu Fuyou Energy Technology Co., Ltd., and others, received the first prize for scientific and technological progress. This achievement adheres to the new coal utilization model of \"pyrolysis+\", overcomes various technical barriers, and enables the clean, efficient, and diversified production of coal-derived products. It allows for the manufacture of high-end chemicals as well as special oils suitable for both military and civilian use, thus providing a new approach to ensuring **energy security**. Original innovation reshapes the “pyrolysis+” model. Coal is the primary energy source in China, and accelerating its clean, efficient, green, and low-carbon conversion and utilization is of great significance for advancing the country’s energy revolution and helping to achieve the \"dual carbon\" goals. In 2004, Shaanxi Coal Group put forward the concept of \"clean and efficient comprehensive utilization of low-grade coal based on differentiated treatment,\" which involves using coal pyrolysis as a key approach, with the goals of achieving high efficiency in energy conversion, high utilization rates of carbon, hydrogen, and oxygen, energy conservation and emission reduction, as well as the production of high-quality products. This approach entails a multi-product production route for the clean and efficient transformation of low-grade coal, achieved through the integrated use of four different levels of coal transformation technologies. Low-grade coal is a product formed in the early stages of coalification; it has a low carbon content and calorific value, while its tar yield and hydrogen-oxygen content are relatively high. “This chemical composition and heating behavior of low-rank coal determine the need for classification by quality in order to enable efficient conversion and utilization. It involves converting this coal into three types of products through medium- and low-temperature pyrolysis: gas (coal gas), liquid (coal tar), and solid (semi-coke). Further processing then yields clean fuels such as oil, gas, and electricity, as well as high-value chemical products; this process is distinctly different from methods such as combustion, gasification, and liquefaction. ”Shang Jianxuan, deputy general manager of Shaanxi Coal Group Company and director of the **Key Laboratory for Clean Conversion of Coal Based on Different Quality Levels, told reporters. Leveraging the abundant reserves of low-rank, oil-rich coal in northern Shaanxi, Shaanxi Coal Group has been committed to innovative exploration in the field of clean and efficient utilization of low-rank coal. Through collaboration among industry, academia, and research institutions, it has carried out numerous efforts to develop key core technologies as well as conduct industrialization trials and demonstrations, striving to maximize the dual functions of coal as both a fuel and a raw material. As a result, a series of internationally leading industrial technology achievements have been developed. Two technologies address industry challenges. Coal pyrolysis and coal tar processing, as key technologies for the selective conversion of coal, face various technical issues such as low heat transfer efficiency, difficulties in separating oil, dust, and gas, challenges in converting asphaltene, and low yields of specialty oils. To address these bottlenecks, the project team carried out extensive technical research and development, creating two core technologies: segmented multi-layer pyrolysis of low-rank coal using gas as a heat carrier, and directional conversion of naphthenic oils through hydrogenation of all fractions of medium- and low-temperature coal tar. The gas-based heat carrier segmented multi-layer low-rank coal pyrolysis technology features the following innovations. First, a gas heat carrier pyrolysis process was developed, which improved the quality of the gas and the yield of tar. The effective content in the gas increased from 45% to over 84%, and the tar yield increased by more than 35%. Secondly, an efficient separation technology for oil, dust, and gas was invented, overcoming the challenges associated with such separation; the dust content in the tar is less than 0.5%. Thirdly, a high-efficiency multi-stage pyrolysis furnace for mixed coal was developed, featuring an innovative three-stage design for drying, carbonization, and cooling. A heat circulation system for coke dry quenching as well as for the hot and cold gases generated during raw material drying was established, thereby improving the efficiency of mass and heat transfer between the heat carrier and the raw coal. This enabled the pyrolysis of mixed coal particles of all sizes up to 30 millimeters; the system’s energy conversion efficiency increased from 85% to over 91%. Medium- and low-temperature coal tar contains a wide variety of compounds, with the main components being polycyclic aromatics, alkanes, phenols, and sulfur- and nitrogen-containing compounds. Due to technical limitations, the existing processing technologies can only produce conventional fuel oil and delayed coking. The technology for the directional hydrogenation transformation of the full fraction of medium- and low-temperature coal tar into naphthenic oils, developed by the project team, has opened up a new route for producing specialty oils from medium- and low-temperature coal tar. An efficient pretreatment technique for coal tar was also invented, enabling the removal of water, metal ions, and chloride ions from coal tar with an efficiency of over 95% ； Overcoming the technical challenge of converting asphaltenes, with a conversion rate of over 98% ； Catalysts for the directed conversion of coal tar into naphthenic oils were developed, increasing the naphthenes yield to over 45%. On this basis, through systematic optimization, the project team developed a complete set of integrated technologies for the differentiated conversion of low-grade coal into special oil products. This system comprises 35 units related to pyrolysis, coal tar processing, the utilization of gas and semi-coke, as well as the recycling of waste materials, thereby creating a system that integrates the conversion of substances and energy derived from low-grade coal. Model projects drive industrial transformation; currently, these two core technologies have been put into industrial use at Shaanxi Coal Group. In March 2016, a 500,000 tons per year mixed coal pyrolysis plant was put into operation at Shaanxi Northern Shaanxi Qianyuan Energy and Chemical Co., Ltd. In July 2018, this technological achievement was evaluated by the China Petroleum and Chemical Industry Federation and found to have comprehensive performance at an internationally leading level. In October 2020, an industrial demonstration plant for the hydrogenation of the full fraction of coal tar at a capacity of 500,000 tons per year to produce naphthenic oils was built by Shenmu Fuyou Technology Energy Co., Ltd. This project has opened up a new pathway for producing high-value specialty oils and fine chemical products from coal tar, thereby expanding the production options for naphthenic oils, which are scarce resources in China. The person in charge of Shenmu Fuyou Company said that since the full production process was put into operation in May 2021, the plant has been running stably, producing naphthenic oil products such as transformer oil, refrigerant oil, white oil, and rubber filling oil, as well as the fine chemical cyclohexane; as a result, the added value of these products has increased significantly. At the same time, they also successfully developed coal tar-based rocket kerosene and special military oils, mastering the key core technologies. The successful operation of this demonstration device lays the foundation for large-scale application. The reporter learned that the system integration technology for the selective conversion of low-grade coal into specialty oils has been applied in the world’s largest modern coal chemical project – the Shaanxi Coal Chemical Yulin 15 million tons/year coal selective, clean, and efficient conversion demonstration project. The reserves and production of low-rank coal in our country account for over 55% of the total national figures and 57% respectively, and are mainly found in regions such as Shaanxi, Inner Mongolia, and Xinjiang. If this technological achievement is widely applied, it will not only significantly improve the level of clean and efficient utilization of coal in our country, but it will also contribute to the industrial upgrading and high-quality development of the northwest region.