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鼓泡流化床中结构与“三传一反“的关系””; StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow Stru Basic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow Stru Basic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow Stru Basic Researches on Relationship between Flow Structure and cture and cture and cture and cture and cture and cture and cture and cture and “Transport “Transport “Transport “Transport “Transport “Transport “Transport “Transport “Transport “Transport -Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” in Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling
吕小林
学位类型博士
导师李洪钟
2015-05
学位授予单位中国科学院研究生院
学位专业化学工程
关键词鼓泡流化床 三传一反 多尺度结构 动力学 一氧化碳催化氧化
摘要鼓泡流化床在微观上存在颗粒,在介观上存在气泡及乳化相,是个复杂多尺度结构,其中气泡的汇聚和破碎,以及颗粒群的聚散对气固间传递具有重要的影响。这使得研究鼓泡流化床内介观结构与传递之间的关系尤为重要。目前鼓泡流化床结构研究主要通过单个结构参数如气泡或聚团,或采用稳定条件的方法来研究,没有采用封闭建模的方法研究床结构。同时,过往描述鼓泡流化床气固曳力以及传质系数时,常采用均匀结构的方法,这没有体现鼓泡床内非均匀结构特性,特别是介观结构的作用。针对以上问题,本课题将根据力平衡,质量守恒定律及经典的经验公式,建立封闭模型得到鼓泡流化床内介观结构参数,从而进一步研究介观结构与动量传递,质量传递及反应过程之间的关系。具体过程为采用多尺度分析方法,建立结构参数模型,再通过动量守恒,质量守恒定律建立基于不均匀结构的曳力系数模型,传质系数模型,并使用双流体模型分析气固流动行为,以及采用臭氧分解和CO催化氧化为模型反应分析流化床内传质与反应。 针对鼓泡流化床复杂的结构,先对整个床层进行尺度分解,再根据力平衡,质量守恒及经典的结构关联式,建立可描述鼓泡流化床内部结构的结构参数模型,以及根据动量,质量守恒定律建立基于不均匀结构的曳力系数模型。在研究过程中,描述鼓泡流化床的六个结构参数通过结构参数模型封闭求解得到。对比计算结果中的各个结构参数之间关系,可以发现各个结构变量能正确描述鼓泡流化床,并能反应鼓泡流化床结构参数之间的关系。 动量传递与床层结构密切相关,也是质量传递研究的基础。为研究床层结构对动量传递的影响规律,本文借用Fluent中自定义函数将结构参数模型以及基于不均匀结构的曳力模型耦合到双流体模型中,对A、B类颗粒在鼓泡流化床中流动行为进行二维或三维模拟。在模拟过程中对A类颗粒在二维三维床中的轴向、径向浓度,运动速度大小及方向等进行分析研究。模拟结果显示颗粒运动呈现中间向上运动,边壁向下运动形态,并显示出明显的环核结构,而且二维三维轴、径向浓度与实验值基本吻合。在B类颗粒模拟中,通过分析可以清晰看到气泡的形成,生长过程,以及完全流态化后气泡稳定的运动形式。 在前面对结构以及动量传递的研究基础上,进一步研究鼓泡流化床内结构和质量传递的关系。首先根据物料守恒建立局部平均结构传质系数,乳化相结构传质系数以及相间相结构传质系数。采用臭氧分解作为模型反应,分析了臭氧在流化床内浓度分布以及传递的控制步骤。结果显示在鼓泡流化床内气泡相和乳化相之间的目标组分交换是臭氧分解的控制步骤,同时通过与实验值比较,结构传质系数模型能很好预测臭氧浓度分布。 最后采用CO催化氧化对鼓泡流化床质量传递进行实验研究,弥补文献上鼓泡流化床质量传递实验控制步骤模糊这个不足之处。在消除外扩散影响下,测量CO催化氧化的指前因子和活化能。此外在鼓泡流化床中测量轴向浓度及出口浓度。通过CO催化氧化的动力学分析可知此反应在速度0.017m/s-0.025m/s属于外扩散控制,并测得表观动力学方程为:。同时在模拟结果中CO的轴向浓度,出口浓度能够很好预测。
语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/20337
专题研究所(批量导入)
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吕小林. 鼓泡流化床中结构与“三传一反“的关系””, StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow Stru Basic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow Stru Basic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow StruBasic Researches on Relationship between Flow Stru Basic Researches on Relationship between Flow Structure and cture and cture and cture and cture and cture and cture and cture and cture and “Transport “Transport “Transport “Transport “Transport “Transport “Transport “Transport “Transport “Transport -Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” Reaction” in Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling Fluidized Bedn Bubbling[D]. 中国科学院研究生院,2015.
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