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鼓泡塔反应器内的气含率结构分析及模型计算
Alternative TitleModelling and Analysis of Gas Holdup Structure
王玉华
Subtype博士
Thesis Advisor李静海
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline化学工程
Keyword能量最小多尺度   鼓泡塔   模拟退火   床层塌落法
Abstract摘 要 鼓泡塔反应器被广泛应用于化学工业、生物化工和环境工程等领域。然而,由于鼓泡塔反应器内流体力学的复杂性,反应器的放大、设计依然没有足够的理论依据。本文的研究目的主要是:(1)借助实验测量结果来分析鼓泡塔反应器内的气含率演化过程及气含率结构,为鼓泡塔反应器的设计和放大提供理论基础;(2)将气-液DBS模型推广到MBS模型。具体内容如下: 1、考察了分布器结构对气含率轴向演化规律的影响。结果表明,气相的初始分布是影响气含率轴向演化的一个重要因素。对于气体初始分布严重恶化的情况下,当h/D=3.33时,轴向气含率的演化仍不够充分;对于性能良好的分布器,在h/D=0.93时,气含率轴向演化已经基本达到充分。 2、应用差压传感器研究气含率的床层塌落曲线形状时发现,床层塌落曲线的形状与检测位置有关。只有低压点的位置距离反应器底部足够的高度时才能获得相对理想的床层塌落曲线。 3、分布器的结构影响了气泡的初始分布,从而影响了体系的气含率结构。在反应器内,小气泡的气含率在径向的分布基本是均匀的,而大气泡则主要往塔中心聚集。 4、将模拟退火算法应用于DBS模型的求解,并将DBS模型推广到MBS模型。当m≥2时,MBS模型退化成DBS模型。这意味着双泡分布是鼓泡塔气液系统中的内在特性,反应了该系统中两种不同的控制机制。 关键词:能量最小多尺度,鼓泡塔,模拟退火,床层塌落法
Other AbstractAbstract Bubble columns are widely used in chemical, biochemical and petrochemical industries. The design and scale-up of bubble column reactors are still very difficult due to the complex characteristics of hydrodynamics. The purposes of this paper is to analyze the structural evolution of gas holdup in bubble columns through experiments and to extend the DBS(dual-bubble-size) model to MBS(multi-bubble-size) model, which will provide the theoretical basis for the design and scale-up of reactors. The effect of gas distributor on the axial evolution of gas holdup is investigated, showing that the radial diffusion of gas phases has an important influence on the axial distribution of the gas holdup. If the performance of gas distributors is very poor, the axial evolution of gas holdup does not still finish even at h/D=3.33. However, the axial evolution of gas holdup is nearly developed at h/D=0.93 if the performance of gas distributor is very good. The profile of gas disengagement is investigated with Differential Pressure Sensor(DP). Experimental results show that the profile of DGD is related to the testing location. The nearly ideal profile is obtained only when the low pressure testing point is high enough from the bottom of the reactor. The structure of gas distributor influences the initial distribution of small bubbles and large bubbles and thus influences the structure of gas holdup in the bubble column. The radial distribution of gas holdup of small bubbles is uniform in the bubble column. However, large bubbles mainly move to the center of the bubble column. Simulated annealing(SA) algorithm is applied to solve the DBS model, and the DBS model is extended to MBS model. In-depth analysis of the variation of structure parameters and bubble size distributions of MBS models(m>=2) indicates that two bubble classes are still predominant just as the situation of DBS model. Therefore the MBS models are essentially reduced to the DBS model. This implies that the DBS model may be an intrinsic model for describing the system evolution and gas-liquid interaction, reflecting two different dominant mechanisms in the system. Key words: Energy-Minimization-Multi-Scale, Bubble Column, Simulated Annealing, Dynamic Gas Disengagement
Pages117
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8276
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
王玉华. 鼓泡塔反应器内的气含率结构分析及模型计算[D]. 中国科学院研究生院,2013.
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