木质纤维素预处理物系的流变学特性表征以及计算流体力学模拟  

Characterization of Rheological Properties of Pseudo Corn Stover Fluid and Computational Fluid Dynamics Simulation

作　　者：乔庆安[1] 李传航[1] 张建[1] 鲍杰[1] 

机构地区：[1]华东理工大学生物反应器工程国家重点实验室,上海200237

出　　处：《华东理工大学学报（自然科学版）》2013年第4期419-426,共8页Journal of East China University of Science and Technology

基　　金：国家重点基础研究发展计划"973"计划(2011CB707406);国家"863"项目(2012AA022301);国家自然科学基金(20976051);教育部博士点基金(20090074110013);中国博士后基金(2011M500742/2012T50380/2012M520850);中央高校基本科研业务费专项资金(WF0913005/1114054/1214025);上海市重点学科建设项目(B505)

摘　　要：预处理是木质纤维素生物炼制中的关键环节。传统的预处理一般在实验室规模的小尺度条件下进行,并未考虑大尺度反应器内的搅拌及搅拌桨型式对混合、传热和传质及预处理效果的影响。研究了在无游离水相存在的干式稀酸预处理反应器中,引入螺带搅拌桨强化混合和传递的可行性,对由固体玉米秸秆颗粒构成的固相体系进行了"拟流体"假设,针对木质纤维素吸水性强、流变学特性无法直接测定的特点,通过测定搅拌体系的扭矩值间接获得秸秆物系的表观黏度(ηa)和表观剪切速率(γeff),从而获得了表征秸秆物系虚拟流体的流变指数(n)和稠度系数(Kpl);建立了干式预处理过程的计算流体力学(CFD)模型,并通过比对秸秆物系冷模实验和CFD模型计算的功率消耗和混合时间,验证了所建模型的准确性。CFD模拟和冷模实验的结果表明在无游离水相存在的干式预处理反应器中引入螺带搅拌桨进行强化混合和传递是可行的,并为带有搅拌的预处理反应器的放大和加工提供了依据。Pretreatment is the most important step during biochemical conversion of lignocellulose to biofuels and biochemicals. However, lack of mixing in the conventional pretreatment process resulted in the deficiency of mixing, heat- and mass-transfer, the non-conformity of the pretreatment intensity, and thus led to the partial insufficient of lignocellulose structure decomposition, and partial excessive decomposition of the lignoeellulose structure to generate inhibitors, which in turn impeded the subsequent enzymatic hydrolysis and microbial fermentation. This study aims to demonstrate the viability of introducing helical-impeller mixing into the dry dilute sulfuric acid pretreatment process. Firstly, considering the high ability of water-adsorption and the resulted difficulty of rheologcial property characterization of the corn stover system, the rheological property parameters of flow index （n） and the consistency coefficient （Kpl） were obtained through calculating the apparent viscosity （ηa） and the apparent shearing rate （γeff） of the corn stover system according to the power law model. Furthermore, CFD models of the dry dilute sulfuric acid pretreatment in a helical stirring bioreactor using the obtained rheological property parameters were constructed, and the CFD simulation results were in agreement with the cold- mold results in three different scale bioreactors. The results of both CFD simulation and cold-mold experiments showed that the practicability of introducing helical impeller into the dry dilute sulfuric acid pretreatment bioreactor.

关 键 词：木质纤维素拟流体 流变学参数 干式预处理 计算流体力学(CFD) 螺带搅拌桨 

分 类 号：TQ018[化学工程]