共查询到19条相似文献,搜索用时 109 毫秒
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采用改进皮托管测定了液固下喷自吸环流反应器中的液体平均速度及液相湍流强度分布,采用PV4A颗粒浓度速度测量仪测定了固含率分布。试验结果表明:随着液体喷射流量的增大,液体平均速度、液相湍流强度及固含率均增大;在导流筒内液相平均速度近似管流分布,在环隙中的速度分布基本均匀;在导流筒和环隙内固含率沿径向分布均匀。该研究对于下喷环流反应器的放大与优化有重要指导意义。 相似文献
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环隙鼓泡型环流反应器的研究 总被引:1,自引:0,他引:1
前言环流反应器是近年来发展较快的一种新型反应器。它不仅具有一定的回流作用还具有较好的传热、传质和混合特性,因此在生化工业和化学工业中已有较多的应用。环流反应器按进料方式,可分为内管进料和环隙进料两种,对于前者已有不少研究报告,而有关环隙进料环流反应器的研究只有 Koide 等做了一些工作,至于气、液混合特性至今尚未见到文献报导。本工作是在环隙鼓泡型环流反应器冷模装置中进行气含率、液侧体积传质系数和流动特 相似文献
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气升式环流反应器是一种结构简单,传质、传热效率高的多相反应器,反应器性能受物性参数和结构参数的影响,由于两相和三相流的复杂性,使得其在工业化设计放大和应用过程中存在困难。论述了气升式环流反应器内相间作用力类别和计算模型,对应用于气升式环流反应器模拟计算的简化模型、两相流模型和k-ε湍流模型进行总结,在分析现阶段气液两相流理论的基础上,明确反应器内不同流动形态下相间作用力、气泡的分散机理、气泡对湍流的影响、流动模拟模型的选取标准,能有效提高气升式环流反应器模拟的准确性及模型的普适性,为反应器的设计放大及传质模拟计算提供更加可靠的理论依据。 相似文献
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本文以空气-水为实验体系,考察了下喷式环流反应器的传质特性与空塔气速、液速以及反应器结构尺寸等参数的关系。得出了最优的导流筒直径与反应器直径之比为0.4—0.5,给出了谊反应器容积传氧系数的计算关联式:与其它反应器相比,该反应器表现出良好的传质特性,具有较大的容积传氧系数。 相似文献
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以空气-水为物系,对无导流筒的下喷式环流反应器中局部性能进行了研究,观测了各种操作条件和结构参数对反应器内流体力学参数的影响,并对反应器内的流动区域进行了划分。 相似文献
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带导流筒的下喷环流反应器的模拟及研究 总被引:1,自引:0,他引:1
本文通过引入二维拟均相κ-ε模型方程,建立了描述气液下喷环流反应器内管流区流体流动规律的数学模型,并进行了求解,模型值与试验值吻合较好。以空气-水-玻璃球为研究物系,对有导流筒的下喷式环流反应器中局部液相性能进行了较深入研究,并分析了各种参数对反应器内流体流动状况的影响 相似文献
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The local gas-phase flow characteristics such as local gas holdup (εg), local bubble velocity (Vb) and local bubble mean diameter (db) at a specified point in a gas-liquid-solid three-phase reversed flow jet loop reactor was experimentally investigated by a five-point conductivity probe. The effects of gas jet flow rate, liquid jet flow rate, solid loading, nozzle diameter and axial position on the local εg, Vb and db profiles were discussed. The presence of solids at low solid concentrations not only increased the local εg and Vb, but also decreased the local db. The optimum solid loading for the maximum local εg and Vb together with the minimum local db was 0.16 × 10-3 m3, corresponding to a solid volume fraction, εS = 2.5%. 相似文献
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为了研究倾角(q)和管径对低温气液两相流中Taylor气泡长度分布规律的影响,在6种管路倾角下,以液氮为工质,使用高速相机对4种内径透明抽真空Pyrex玻璃管内的弹状流动进行了可视化实验. 结果表明,低温弹状流动中Taylor气泡长度分布的统计特征可由对数正态分布函数描述,Taylor气泡长度分布的标准偏差受到液膜射流直接影响,并随q减小先增大后减小. Taylor气泡无量纲平均长度随管路轴向位置增大而线性增加,随管路内径增加呈指数下降趋势,随q减小而增大,最小值出现在70o≤q≤90o. 相似文献
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Keiji Yasuda Yufei Wang Koichi Haneda Testuya Naito Yoshiyuki Bando Tomokiyo Takeyama Yasuhito Kawase 《加拿大化工杂志》2010,88(4):518-522
Micro‐bubbles were dispersed in the bubble column with draft tube, and the length and diameter of draft tube were changed. The flow characteristics in air–water system were measured. Ozone gas and methylene‐blue aqueous solution were used, and the decomposition performance was examined. With increasing draft tube length, both the gas holdup and liquid velocity in the annular section increased. When the diameter ratio of draft tube to column was about 0.5, both the gas holdup and liquid circulation flow rate had maxima. For the decomposition by using ozone, the installation of draft tube enhanced the mass transfer and decomposition performance. 相似文献
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下喷自吸环流反应器内液相局部流动特性 总被引:1,自引:0,他引:1
对下喷自吸环流反应器内气-液两相流和气-液-固三相流体系的液相局部流动物性进行了深入的实验研究。采用改进皮托管法和线-线双探针电导法分别对液相瞬时速度和液含率进行了微机在线测量,并借助湍流统计理论对液相局部流动参数和局部液含率进行了统计分析和处理,着重讨论了喷射液体流量和固体粒子加入量分别对喷射有效区和导流筒内管流区液相局部流动参数和液含率的影响。 相似文献
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A. Bakopoulos 《Chemical engineering science》2006,61(2):538-557
A solution methodology is proposed for the process development and process engineering of a continuously operated jet loop bubble column including integrated external or internal steam generation for, e.g., a high-efficiency large-scale medium pressure methanol and or dimethyl ether production, or other gas to liquid Fischer-Tropsch applications.A jet loop bubble column is defined in the present process development to study the combined integration of a jet-eductor draft tube system with an upper bubble column. The major advantages resulting from the integrated jet-eductor draft tube system in large-scale bubble columns are the guidance and good mixing efficiency of the multiphase flow up to the upper part of the bubble column. Reducing the bubble column operating liquid level at about 2.5-3.0 times of the column diameter above the upper end of the draft tube results in a classical jet-eductor draft tube reactor suitable for small and or medium-scale industrial applications.Methanol synthesis is usually executed catalytically in multistage packed beds at higher pressure, e.g. 26 MPa, and about 350-, resulting in a higher plant installation and operating cost. The successful scale-up of a slurry jet loop bubble column can achieve a higher catalytic selectivity at a lower pressure and temperature , and therefore reduce the overall plant investment and production cost [Toseland, 1999. Three phase flows under extreme conditions of pressure and temperature, Part II: industrial applications, Air products and Chemicals, Inc. Presented at the A.I.Ch.E. Annual Meeting, Dallas, TX; Fan, 1999. Three phase flows under extreme conditions of pressure and temperature, Part I: fundmental characteristics, Department of Chemical Engineering, The Ohio State University. Presented at the A.I.Ch.E. Annuxal Meeting, Dallas, TX]. In addition, the separate slurry production of dimethyl ether, or even coproduction with methanol, can be a more cost-effective process than the classical methanol dehydration process.The new Modified Slurry Process© for large-scale methanol and or dimethyl ether production is presented including internal or external heat exchanger location for steam production.A process concept is developed of a Large Scale Slurry Jet Loop Bubble Column© with external separator, auxiliary internal heat exchanger equipment and high-efficiency gas-liquid slurry jet-eductor mixing system including draft tubes and an upper bubble column. In addition, as comparison a simplified concept is discussed for a small-to-medium-scale slurry jet loop reactor including external steam production and bottom nozzle jet-eductor installation without the presence of an upper bubble column.The basic geometrical parameters of the proposed slurry jet loop bubble column and jet loop reactor are discussed. The influence of the selected geometrical parameters on the gas holdup, interfacial area and mixing is analyzed. Information about catalyst type and particle size distribution is also presented.The definition of optimal operating conditions related to the influence of the fluid dynamics and mixing on mass transfer efficiency and also information for the minimum required power input per unit volume for startup or stable reactor operation are discussed.A simplified estimation method is presented for the expected axial temperature difference across the overall length of the jet bubble column, and also the required heat transfer area of a new construction-type internal compact heat exchanger for efficient reactor cooling and operation.Scale-up is possible for large diameter jet loop bubble columns, typically up to 5 m diameter and 60 m height, including continuous three-phase slurry operation at higher power input and interfacial area, for more efficient synthesis gas absorption and reaction than in classical slurry bubble columns. Integration of suitable designed sieve trays can further guarantee an efficient operation of the lower jet loop draft tube system at higher column diameters and also achieve an efficient reactor operation in the upper bubble column section. 相似文献