【作者】 王旭；

【导师】 史启才； 刘志军；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2006， 硕士

【摘要】 涡旋波膜生物反应器是将涡旋波流动与膜生物反应器技术相结合,利用涡旋波流动在雷诺数较小的层流状态下良好的局部混合特性,产生强制对流,加快动量交换速率,达到增强传质的目的。而且其剪切应力和能量消耗与传统的依靠湍流来强化气液传质相比要小得多,提高了微生物细胞在膜生物反应器中的存活率,解决了传统膜生物反应器堵塞和浓差极化等问题,有很重要的研究价值。 本文通过实验的方法对涡旋波膜生物反应器进行传质性能测试,并利用数值模拟的手段对反应器内的剪应力分布等参数进行了计算,主要内容如下: 建立涡旋波膜生物反应器实验装置,本反应器为间歇式反应器。对不同槽道结构进行冷模传质实验,并用反应器对人工合成废水进行生化处理,对生化反应过程中的传质性能进行测试,不同时刻出水处理效果通过测试化学需氧量(COD)值来衡量。通过对实验结果的分析,可以得出:①涡旋波流动可以显著增强气液传质效果,相对于稳定流动而言体积传质系数k_La平均增幅为26.67%;②减小折流间距L可以进一步强化传质效果,折流间距越小,k_La值越大,强化效果越显著,L与k_La平均增幅符合对数形式增长关系:k_La(%)=-14.537Ln(L)+79.846;③不同槽道结构中Re数对k_La都具有显著性影响。在此基础上对涡旋波在层流流动下强化传质的机理进行了分析。 通过对涡旋波膜生物反应器中的两相流流场进行数值模拟,系统地研究了反应器内的剪应力的分布规律:①壁面、涡心、旋涡生成处及非旋涡生成区的剪切应变依次降低;②随着Re数的增大,扩张区内剪应力的平均值呈线性增加趋势。 本文定量的分析了涡旋波流动在低雷诺数下气液传质特性,为今后进一步研究涡旋波膜生物反应器及其工业化应用提供了一定的实验基础。更多还原

【Abstract】 In order to enhance performance of mass transfer, the vortex wave MBR can be used as a novel technic. It combines vortex wave flow and MBR technic, which using vortex wave can generate very effective local mixing and come into being forced convection, expedite momentum exchange under the condition of laminar flow with low Re number. Compared with traditional methods of enhancing mass transfer by using turbulent flow, the shearing stress and the power dissipation in the vortex wave MBR are rather low. It is very worthy, which increases survival rate of microorganism cells and can also solve some problems such as clogging and concentration polarization in the traditional MBR.In this paper, the parameters of mass transfer performance are experimentally tested in the vortex wave MBR, and the distribution of shearing strength in the vortex wave MBR is investigated by using numerical simulation method. The following contents are discussed.A set of experimental equipment of vortex wave MBR is established, which is sequence reactor. The mass transfer experiments of water and synthesis wastewater are carried out for different channel structures. The mass transfer performance and the results of wastewater treatment are evaluated by chemical oxygen demand (COD) of influent and effluent. Some experimental results are obtained: ① Vortex wave flow may remarkably enhance gas-liquid mass transfer, and the overall volumetric mass transfer coefficient (k_La) averagely increases 26.67% comparing with that of the steady flow. ② Mass transfer can be further enhanced by reducing deflector spacing L in the channel. The relation between L and k_La can be described as following: k_La(%)= -14.537Ln(L)+79.846. ③ The Re number has an important effect to k_La in all kinds of channel structures. Based on the above research results, the mechanism of significant mass transfer enhancement under laminar flow conditions is analyzed.The numerical simulation of two-phase flow field in the reactor is carried out in this paper. The distribution of shearing strength in the channel is systematically obtained: ① The shearrates of wall, vortexcore, vorticity and non-vorticity regions are descending sort. ② With Re number increasing, the average of shearing strength becomes linearly increasing tendency in the back step expand channel.This paper quantitatively studies the mass transfer characteristic of the vortex wave with low Re number. It provides experimental and design foundation for further study andindustrialization of the vortex wave MBR.更多还原