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A Record of the Development of Pulverized Coal Pyrolysis Technology by Yulin Jiahe Coal Pyrolysis Company / Author/Source: Sinochem New Network / Date: 2020-08-05 / Clicks: 12 Recently, the **Energy Bureau conducted a special investigation in Shaanxi regarding the clean and efficient conversion as well as differentiated utilization of coal during the 14th Five-Year Plan period. The scientific and technological achievement developed by Yulin Jiahe Coal Pyrolysis Technology Development Co., Ltd., namely \"Research on the Industrialization Technology Development of Mobile Bed-Boiling Bed Coupled Pulverized Coal Pyrolysis (Low-Temperature Carbonization)\", has attracted the attention of relevant experts, who intend to adopt this achievement as one of the new technologies for pulverized coal pyrolysis. China’s resource profile, characterized by abundant coal but limited oil and gas, means that coal will remain the dominant energy source for a long time to come. The clean and differentiated utilization of coal has become a key focus and main direction of energy strategies. As an important method for the differentiated utilization of coal and its clean and efficient conversion, medium- and low-temperature pyrolysis technology has been included in the \"Action Plan for Clean and Efficient Utilization of Coal (2015-2020)\" and the \"Action Plan for Innovation in Energy Technology Revolution (2016-2030)\". Low-rank coal, which accounts for more than half of China’s total coal resources, is mainly found in Shaanxi, Inner Mongolia, Xinjiang and other regions. This kerosene has a high content of coal oil and water, making it suitable for medium- and low-temperature pyrolysis. However, the existing pyrolysis processes in China mainly rely on lump coal, which has significant limitations. With the development of comprehensive coal mining technology, 70% to 80% of the mined raw coal is in the form of pulverized coal, which is difficult to convert and utilize effectively. The new low-grade coal pyrolysis process developed by Jia and the company over many years employs an internally heated, externally burning fluidized-bed coal pyrolysis (low-temperature carbonization) technology with four distinct stages – drying, preheating, carbonization, and cooling – and is backed by independent intellectual property rights. This process achieves a tar yield of 8%, a fixed carbon content in the semi-coke product of over 84%, a total moisture content of only 0.2%, a volatile matter content of 6%–8%, and a calorific value of 7300–7500 kcal, meeting the specifications for anthracite. Its key parameters such as fixed carbon, moisture, strength, and specific resistance are all superior to those of grade 1.5 semi-coke products, making it an excellent raw material for the production of calcium carbide and ferrosilicon. Why is the quality of the semi-coke product better than that obtained using conventional coal pyrolysis techniques? Liu Xicun, the chairman of Jiahe Company, told reporters that the key lies in their use of a combination of moving bed and bubbling bed systems for coal pyrolysis. In this system, a moving bed is used in the preheating stage and a bubbling bed is used in the dry distillation stage, thereby enabling staged coupled pyrolysis of pulverized coal. This approach combines the advantages of internal and external heating, ensuring uniform heating of the pulverized coal and high thermal efficiency. The pyrolysis temperature can be maintained at a relatively low level of around 600°C, and it is also controllable. This scientific and technological achievement passed the evaluation organized by the Shaanxi Petroleum and Chemical Industry Federation in mid-April. Experts believe that this technology has overcome the key technical challenges associated with coal dust pyrolysis; it features significant innovation and is at the leading level in China, opening up new technological pathways for coal dust pyrolysis in our country. The development of medium- and low-temperature coal pyrolysis technology in our country is progressing rapidly, but the technology for pulverized coal pyrolysis has not yet seen complete breakthroughs; the main constraint is the online separation of pyrolysis oil, gas, and coal dust. Company A cleverly installed dust removal facilities in the preheating and carbonization sections, removing coal dust from the gas and reusing it, thereby solving the problems of easy clogging in the coal powder pyrolysis system and the high dust content in tar that made separation difficult. They also overcame the key technical challenge of gas-solid dust separation associated with fluidized bed reactors by using moving beds, resulting in a dust content in the tar of less than 0.2%, thus resolving the common technical problems existing in China’s coal pyrolysis industry. The raw materials for this technology are highly practical; all pulverized coal and fine pulverized coal with a particle size of 30 millimeters or less can be utilized. “Fine coal powder with a particle size of less than 0.2 millimeters is difficult to transport and handle, and is prone to catching fire. ”Liu Xicun said that, based on the characteristics of pulverized coal, the company developed its own drying device for it, using the hot flue gas from heated recycled gas to heat and dry the pulverized coal, reducing the moisture content to 3%–5%. Slight adjustments to the process parameters can also make it suitable for lignite with a higher moisture content. By utilizing this technology, Company A built an industrial demonstration facility for coal powder pyrolysis (low-temperature carbonization) with an annual capacity of 100,000 tons in the Yushen Industrial Zone in Shaanxi in May 2016. The facility was operated and optimized on multiple occasions, enabling the low-temperature carbonization of coal powder with a particle size of less than 30 millimeters. As of June 2019, the unit had accumulated over 3,000 hours of operation, and all performance indicators met the expected targets, confirming the rationality of the process and the reliability of the unit. Ma Fei, deputy director of the Yushen Industrial Zone Management Committee, told reporters that semi-coke (lignite carbon) is one of the key industries in Yulin; the region has a complete range of coal pyrolysis technologies, and its production capacity of lignite carbon accounts for more than half of the national total. However, there are still no large-scale industrial facilities for coal pyrolysis that can operate stably, and no significant breakthroughs have been achieved in this technology to date. Company A’s coal powder pyrolysis technology enables the full utilization of coal powder and fine coal powder, which is highly valuable; it provides a solution for the effective use of coal powder in large quantities at low costs. According to Liu Xicun, the company is currently working on the process package design for an industrial project of 300,000 tons per year for coal dust pyrolysis, which will further accelerate the industrial application and dissemination of this technology.