热解条件对秸秆热解特性及生物炭产率的影响

Effects of pyrolysis conditions on pyrolysis characteristics andbiochar yield of straw

为明确秸秆废弃物生物炭制备过程中的热解特性及其与生物炭产率之间的关联,探寻秸秆废弃物制备生物炭的最佳热解条件,以4种不同类型的秸秆废弃物为研究对象,通过热重模拟结合秸秆废弃物的组分特征,考察秸秆废弃物种类、热解终温、升温速率对秸秆废弃物热解特性及生物炭产率的影响.结果表明,4种秸秆废弃物在热解过程中其最大失重量和最大失重速率均出现在热解阶段,最大失重速率排序为:小麦秸秆>玉米秸秆>水稻秸秆>芦苇秸秆,与秸秆自身的纤维素含量相关.统计分析表明,秸秆废弃物种类、升温速率、热解终温、终温保持时间对生物炭产率均有显著影响.热解终温越高、升温速率越大、保留时间越长,生物炭产率越低.热解终温、升温速率对秸秆生物炭产率的影响规律均与热重模拟实验结果相吻合.综合热解特性、生物炭产率统计分析结果及能耗,选定生物炭的最佳制备条件为以10℃/min的升温速率升至500℃,保持30 min.

To clarify the pyrolysis characteristics of straw waste and the correlation with biochar yield in the preparation of biochar,and meanwhile explore the optimal condition for biochar preparation from straw waste,four different types of straw waste were selected to investigate the effects of straw waste type,final pyrolysis temperature,and heating rate on the pyrolysis characteristics and biochar yield of straw waste by thermogravimetric simulation combined with the component characteristics analysis of straw waste.Results show that the maximum weight loss and maximum weight loss rate both appeared at pyrolysis stage,and the order of maximum weight loss rate was:wheat straw>corn straw>rice straw>reed straw,relating to the cellulose content of the four types of straw.Statistical analysis shows that straw waste type,final pyrolysis temperature,heating rate,and retention time all had significant effects on biochar yield of straw waste.The higher the final pyrolysis temperature was,the faster the heating rate and the longer the retention time were,and the lower the biochar yield was.The effects of final pyrolysis temperature and heating rate on the biochar yield of straw were consistent with the thermogravimetric simulation results.According to the pyrolysis characteristics and statistical analysis of biochar yield and energy consumption,the optimal condition of biochar preparation was:heating to 500℃at a rate of 10℃/min and keeping for 30 min.