小型搅拌热解气回燃式生物质炭化炉设计与试验

Design and Experiment of Small Carbonization Kiln with Biomass Stirring and Backburning Mechanism

摘要:

针对传统炭化工艺温度不均、尾气净化难、能量消耗大的问题，设计了一种小型搅拌热解气回燃式生物质炭化设备。采用双螺旋带搅拌，使生物质横向对流，受热均匀；设计热解气引流装置使其回流至燃烧室引燃，减少热解气排放的同时，为生物质炭化提供能量，降低了炭化能量投入。基于计算机仿真技术建立了样机模型，并对炭化炉温度场及热流场进行了矢量分析，计算结果表明炉内温度分布均匀。设计了炭化炉样机，以稻壳为原料进行生物质炭化试验。结果表明，热解气引燃后炭化室温度能够保证生物质炭化所需条件。正交试验结果表明，最佳炭化率因素水平组合为：螺旋搅拌器转速为43 r/min、炭化室物料充满系数为88.68%、炭化时间为15 min，此时，炭化率最高为50.86%。

Abstract:

Biochar plays a significant role in improving soil properties, promoting restoration of the cultivated land, fixing carbon and reducing emissions, improving the environment, and alleviating the energy crisis. Aiming at the problems of uneven temperature, difficult purification of pyrolysis gas and high energy consumption of traditional carbonization process, a small charring kiln with biomass stirring and pyrolysis reigniting mechanism was designed. The main structure of the kiln included combustion chamber, carbonization chamber, preheating chamber, dual-spiral agitator, and motor. A dual helix auger structure was employed to facilitate the circulation of biomass. By utilizing smoke exhaust technology, the recirculation of exhaust gases back to the combustion chamber for ignition was achieved. This approach not only reduced tailpipe emissions but also decreased the energy input required during carbonization. A prototype simulation model was established and vector analysis on the temperature field and heat flow field of the carbonization furnace was performed based on computer simulation technology. The calculation results indicated that the temperature distribution inside the furnace was uniform. The biomass carbonization experiments were conducted by using rice husks with this charring kiln. The results showed that the biomass can be ignited with the leaded back combustible exhausted gases produced in charring process, and it can keep the temperature within the carbonization chamber in the range of 420℃ to 470℃, which met the requirements for carbonization. Orthogonal experimental results indicated that under certain conditions, the optimal combination of factors for the highest carbonization rate were spiral mixer speed of 43 r/min, material filling coefficient of 88.68% in the carbonization chamber, and carbonization time of 15 min. The highest carbonization rate achieved 50.86%. These research findings can serve as a reference for biomass carbonization technology.