Low rank coal reserves are abundant in China, and pyrolysis technology has rapidly developed as the core of cascade utilizationof low rank coal. The pyrolysis of low-rank coals produces a large amount of semi-coke, constituting approximately 50% to 70% of theweight of raw coal and about 80% of the energy of raw coal. However, due to its low volatile content, pure burning semi-coke is restrictedby its poor ignition stability, difficult burnout and high pollutant emission level.The preheating combustion technology emerges as an effective solution to address these issues. In this process, fuel is modified at high temperature in the preheating burner, converting from a singlesolid fuel to a binary high temperature gas and solid mixed fuel, and then sent into the boiler furnace for high efficiency and low nitrogen combustion. Relevant pilot tests have been carried out on the 2 MW test platform. In order to further verify the technical effect, the operating characteristics and NOx emission characteristics of pure burning semi-coke with different loads were carried out on a 60 t/ h preheating combustion boiler for pulverized coal, equipped with two preheating burners in hedged arrangement. The experiment results show thatsemi-coke run stably and satisfactory under boiler loads in the range of 50%-90%, with a rational distribution of furnace temperatures.The parameters of the 26 MWth preheating burners are reasonable,exhibiting stable circulation states and good symmetry. After preheated,semi-coke achieves high efficiency combustion, the combustion and thermal efficiency of the boiler are above 98% and 92.5% under eachload, respectively. By adjusting the air distribution, the original NOx emission under each boiler load is lower than 200 mg/ m3(φ(O2)=6%), indicating that low NOx combustion effect is remarkable. The experimental results provide important support for the design and engineering scale-up of pure semi-coke preheating boiler and can directly provide theoretical data reference for the application of hedge boiler.

朱书骏(1992—),男,黑龙江七台河人,助理研究员,博士。E-mail:zhushujun@iet.cn

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ZHU Shujun,TIAN Jilin,ZHU Jianguo,et al.Experimental study on pyrolysis of semi-coke pure combustion in 60 t/ h preheating combustion boiler[J].Clean Coal Technology,2023,29(12):103-109.