State Key Laboratory of Coal Conversion,Institute of Engineering Thermophysics,Chinese Academy of Sciences
Shanxi Key Laboratory of Coal Flexible Combustion and Thermal Conversion,Datong Institute of Coal Clean and Efficient Utilization
University of Chinese Academy of Sciences

我国低阶煤储量丰富,以热解为龙头的低阶煤梯级利用技术快速发展,其热解产生大量半焦,占原料煤质量的50%~70%,所含能量占原煤的80%左右,然而因半焦挥发分低,燃烧过程中存在着火稳定性差、燃尽难和NOx排放水平高等问题,制约半焦燃烧利用。预热燃烧技术能较好解决上述问题,燃料首先在预热燃烧器中进行高温热改性,由一元固体燃料转化为二元高温气、固混合燃料,再送入锅炉炉膛进行高效、低氮燃烧,已在2MW试验平台上开展了相关中试验证。为进一步验证技术效果,在一台60t/h现役煤粉锅炉上开展了不同中、高负荷条件下纯燃半焦运行特性、NOx排放特性试验,该锅炉配备了2个对冲布置的预热燃烧器。试验结果表明:热解半焦在50%~90%锅炉负荷下运行状态稳定、良好,炉膛温度分布合理;26MWth预热燃烧器各参数合理、循环状态稳定、对称性好;经预热后热解半焦在各负荷下锅炉燃烧和热效率均分别在98%、92.5%以上,实现了高效燃烧;通过调整配风,锅炉各负荷下NOx原始排放均低于200mg/m3(φ(O2)=6%),低氮燃烧效果显著。试验结果为纯燃半焦预热燃烧锅炉的设计与工程放大提供重要支撑,可直接为对冲锅炉应用提供理论数据参考。

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.

国家重点研发计划资助项目(2017YFB0602005)

朱书骏,田继林,朱建国,等.60 t/ h 预热燃烧锅炉纯燃热解半焦试验[J].洁净煤技术,2023,29(12):103-109.

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.