竹粉在CO_2气氛中的热解气化特性及动力学研究

Kinetic Study on Pyrolysis and Gasification Characteristics of Bamboo Powder

利用热重分析仪研究了竹粉在二氧化碳气氛中的热解气化特征,考察了不同升温速率下(5℃/min,10℃/min,20℃/min和30℃/min)竹粉的热解气化动力学参数.竹粉的热解气化主要经历干燥、玻璃化转变、纤维素和半纤维素热解、木质素热解以及炭气化五个反应阶段,重点考察后三个反应阶段.采用Satava-Sesták模型函数法计算竹粉的热解气化动力学参数,结果表明:频率因子随升温速率的增加而增大,反应活化能在纤维素和半纤维素热解反应和炭气化反应两个阶段随升温速率增加而增大,积分形式机理函数是随机成核随后生长型反应模型,模型验证得到的预测结果和试验结果吻合较好.该研究对竹类生物质热解气化利用的工艺参数优化具有重要指导意义.

Thermo-gravimetry （TG） experiments of bamboo powder in CO2 atmosphere conducted with different heating rate ranging from 5 to 30℃/min within 40 to 1200℃ are studied in this paper. The kinetics on pyrolysis and gasification characteristics of bamboo powder are then investigated. The TG experiments results show that the bamboo powder mainly undergoes five stages： drying stage, glass transition stage, cellulose and hemicellulose pyrolysis stage, lignin pyrolysis stage and biochar gasification stage. Classic model -fitting method （Satava - Sesták ） is used to analyze the kinetics parameters in the last three reaction stages. It is shown through the results that the frequency factors in the three reaction stages are increased with the increasing of heating rate. The active energies show the same rule in cellulose and hemieellulose pyrolysis stage and biochar gasification stage. The random nucleation and later growth kinetic model is validated for the pyrolysis and gasification of bamboo, which fits well with the TG experimental results. The study provides a good reference for bamboo pyrolysis and gasifica-tion device design, as well as process parameters optimization.