自吸式反应器搅拌特性的实验研究和数值模拟

发布时间：2018-04-05 08:11

本文选题：自吸式反应器　切入点：临界吸气转速　出处：《华东理工大学》2016年硕士论文

【摘要】：自吸式反应器具有结构简单、能耗小、传质性能好等优点。分别研究了单层桨自吸式反应器和双层桨自吸式反应器的流体力学特性,并进行了单层桨自吸式反应器的CFD数值模拟研究。单层桨自吸式反应器的流体力学特性：临界转速随着搅拌器直径的增大而减小,随着浸没深度的增大而增大；吸气速率随着搅拌转速的增大而增大,随着浸没深度的增大而减小,存在吸气效率最高点,拟合得到了吸气速率的经验公式；整体气含率和体积氧传质系数均随着功率消耗的增加而增加；相对功率PG/P在转速超过临界吸气转速以后随转速增大而减小；临界转速随着液体粘度的增加而增大,吸气速率随着液体粘度的增加而减小,吸气效率最高点随着液体粘度的增加,向单位体积功耗增大的方向偏移。双层桨自吸式反应器的流体力学特性：下层搅拌器形式对临界吸气转速影响很小；采用轴流型下层搅拌器,吸气速率随着桨间距的增大先增大后减小,最佳桨间距为0.75D1。径流型下层搅拌器,吸气速率随着桨间距的减小而增大；单位体积功耗下,反应器整体气含率的性能由下层搅拌器功率准数决定；相对功率PG/P,上翻式下层搅拌器下降较快,下压式搅拌器下降较慢。建立了气液两相流(空气-水)的数学模型,对单层桨自吸式反应器的内部流场分布、局部气含率分布和压力场分布进行了数值模拟研究,并将模拟结果和实验结果进行了比较,两者吻合较好,证明计算流体力学(CFD技术)是进行各类自吸式反应器优化设计和放大的有效手段。
[Abstract]:The self-priming reactor has the advantages of simple structure, low energy consumption and good mass transfer performance.The hydrodynamic characteristics of single-layer propeller self-priming reactor and double-impeller self-priming reactor were studied, and the CFD numerical simulation of single-layer propeller self-priming reactor was carried out.The hydrodynamic characteristics of single-layer propeller self-priming reactor: the critical speed decreases with the increase of agitator diameter and increases with the increase of immersion depth, and the suction rate increases with the increase of stirring speed.With the increase of immersion depth, there exists the highest inspiratory efficiency, and the empirical formula of inspiratory rate is obtained by fitting, and the integral gas holdup and volumetric oxygen mass transfer coefficient increase with the increase of power consumption.The relative power PG/P decreases with the increase of the rotational speed, increases with the increase of the viscosity of the liquid, and decreases with the increase of the viscosity of the liquid.The peak of inspiratory efficiency shifts to the increase of unit volume power consumption with the increase of liquid viscosity.The hydrodynamic characteristics of double-layer propeller self-priming reactor: the form of lower layer agitator has little effect on the critical suction speed, and the suction rate increases first and then decreases with the increase of propeller spacing, and the optimum pitch is 0.75D1.Under the unit volume power consumption, the performance of the overall gas holdup of the reactor is determined by the power standard number of the lower layer agitator.The down-pressure agitator drops slowly.A mathematical model of gas-liquid two-phase flow (air-water) was established. The flow field distribution, local gas holdup distribution and pressure field distribution in single-layer propeller self-priming reactor were numerically simulated.The simulation results are compared with the experimental results. It is proved that computational fluid dynamics (CFD) is an effective method for optimal design and amplification of various self-priming reactors.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ027.2

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