高固含量木质纤维同步糖化与发酵反应器内流体力学特性研究
时间:2018-03-24 21:21 来源:毕业论文 作者:毕业论文 点击:次
| 摘要：搅拌反应器是一种在化工、医药、能源和废水处理等领域应用比较广泛的设备，其中气含率是表征搅拌槽持气特性参数，混合时间是表征搅拌反应器内物料混合状况的一个重要参数，氧传递系数是影响发酵的一个重要参数。针对高固含量木质纤文素同步糖化与发酵生产燃料乙醇过程,本文以羧甲基纤文素钠(CMC)水溶液为液相, 空气为气相, 研究了粘度、转速、通气量等对搅拌过程中气含率、混合时间和氧传递的影响。结果表明，实验体系下，搅拌槽内的氧传递系数在8-16h-1的数量级，其大小随通气量及转速的增大而增加，随体系粘度的增大而降低；实验体系下，气含率最高值可达12%，其值随同通气量及转速的增大而增加，随粘度的增大而降低；对于自来水体系，转速100-300rpm范围内，随着通气量由4L/min升高至8L/min,体系的混合时间大致由（1200-900）s降低至（1000-800）s；对不同粘度体系，混合时间随转速升高而降低，以2%（wt）CMC体系为例，当转速由300rpm增大至700rpm时，混合时间由1180s降低至大约880s左右。20098 关键字： 搅拌器；气含率；氧传递系数；混合时间 Study on the hydrodynamics of the simultaneous saccharificatin and fermentation of lignocelluose reactor at high solids loading ABSTRACT Abstract：Stirred tank is a kind of widely used equipment in chemical, pharmaceutical, energy and waste water treatment industry. The gas hold up is a measurement of the ability to retain the gas of the tank, the mixing time is an important parameter representing the mixing conditions in stirring reactor and the oxygen transfer coefficient is an important influencing factor in fermentation. This article is in the context of simultaneous saccharification and fermentation of lingnocellulose at high solids loading to produce fuel ethanol. Sodium carboxymethyl cellulose dissolved in water was employed as the liquid phase and air as gas phase. The influence of viscosity, rotation speed and gas volumetric flow rate on the above three parameters were investigated. The results show that the mass transfer coefficient(KLa) is in the range of 8-16h-1 under conditions studied. KLa increased with the rotational speed and gas flow rate and decreased with the liquid viscosity. The gas hold up can reach a maximum of 12% and it has the same trend with studied factors as KLa. The mixing time decreased from （1200-900）s to（1000-800）s as the gas volumetric flow rate increased from 4L/min to 8L/min for tap water system. And for the 2%CMC system, the mixing time decreased from 1180 to 880s as the impeller rotational speed increased from 300rpm to 500rpm. Keyword：agitator；gas holdup；the oxygen transfer coefficient；mixing time: 目录 1 引言 1 1.1 研究背景 1 1.2 搅拌流体力学特性概述 3 1.2.1 气含率 3 1.2.2 传质系数 3 1.2.3 混合时间 4 1.3 搅拌原理及其流体流型 4 1.4 国内外反应器内流体力学特性研究概述 5 1.5 研究目的和意义 6 2 材料试剂、仪器设备和采取的方法、技术 7 2.1实验物料和装置的选用 7 2.2 使用的材料试剂、仪器设备 7 2.2.1实验主要设备 9 见图5、6 9 2.2.2实验所用设备概述 11 2.3 搅拌反应器内流体力学特性测定 12 2.3.1 气含率测定 12 2.3.2 气液体系中氧传递系数测定 12 2.3.3 混合时间测定 13 3 实验内容 13 3.1 气含率测定 13 (责任编辑：qin) |