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Technology for segmented coupling of fluidized bed and bubbling bed for coal powder pyrolysis – Author/Source: Collaborative Group on Advanced Processing and Hydrogenation of Coal Tar; Date: 2020-04-21; Clicks: 5. On April 19, the technological achievement titled “Industrialization Development Research on Coupled Fluidized Bed and Bubbling Bed Pyrolysis of Coal Powder (Low-temperature Carbonization)” developed by Yulin Jiahe Coal Pyrolysis Technology Development Co., Ltd. was evaluated in Xi’an by the Shaanxi Petroleum and Chemical Industry Federation. Experts deemed that this technology overcame key technical challenges associated with coal powder pyrolysis, exhibited significant innovation, and reached a level leading in China, thus opening up new technological pathways for coal powder pyrolysis in the country. Jia and Liu Xicun, the chairman of the company, explained that China’s technology for medium- and low-temperature coal pyrolysis has developed rapidly, but progress in coal powder pyrolysis technology has not yet been fully achieved; the main constraint is the online separation of pyrolysis oil, gas, and coal dust. The new pyrolysis process for low-grade coal dust (0-15mm) developed by this company utilizes a proprietary, four-stage (drying, preheating, dry distillation, cooling) external combustion internal heating type fluidized bed coal dust pyrolysis (low-temperature dry distillation) method, combining the advantages of both internal and external heating approaches. The preheating section uses a moving bed, while the dry distillation section employs a bubbling bed; this setup enables staged coupled pyrolysis of coal powder, with the pyrolysis temperature being controllable. At the same time, dust removal facilities are cleverly installed in the preheating section and the carbonization section, effectively removing coal dust from the gas and reusing it, thus solving the problems of easy clogging in the pulverized coal pyrolysis system and the high dust content in tar that makes separation difficult. The appraisal committee, headed by Li Wenhong, a professor at the School of Chemical Engineering at Northwest University, concluded that the segmented coupled pyrolysis technology using a moving bed and a bubbling bed enables controllable pyrolysis temperatures, ensures uniform heating of the pulverized coal, and achieves high thermal efficiency. The key technical challenge of gas-solid dust separation, which arises in fluidized bed reactors, was resolved by using a moving bed; the dust content in the tar is less than 0.2%. This approach overcame the common technical difficulties faced by China’s coal pyrolysis industry, and it is recommended that its industrial application be accelerated. In May 2016, Party A and the company built an industrial demonstration facility for coal powder dry distillation with a capacity of 100,000 tons per year in the Yushen Industrial Zone in Shaanxi. The operation of this facility was carried out on multiple occasions, with optimizations made to enable the low-temperature dry distillation of coal powder with a particle size of less than 30 mm. As of June 2019, the unit had accumulated over 3,000 hours of operation, and all performance indicators met the expected targets, verifying the rationality of the process and the reliability of the unit. Among them, the tar yield reaches 8%, the fixed carbon content in the semi-coke product is greater than 84%, the moisture content is less than 1%, the volatile matter content is as high as 6%-8%, and the calorific value is 7300-7500 kcal, meeting the specifications for anthracite. To date, Company A has obtained 8 utility model patents, with 2 invention patents currently under review.