共查询到19条相似文献,搜索用时 109 毫秒
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两级气液内环流反应器内气含率和循环液速 总被引:3,自引:2,他引:3
基于多釜串联可以有效减小返混的原理,通过引入特殊设计的级间构件构建了一种新型的两级内环流反应器。实验研究了级间构件形式、表观气速、表观液速和气液分离器对每一级内气含率和循环液速的影响。实验结果表明,表观气速对反应器二级(上一级)中上升管与下降管气含率之差和循环液速影响较大,而对一级(下一级)的影响较小;各级内上升管和下降管的气含率均随表观液速的增大而减小,但影响程度较小。基于推动力和阻力平衡建立了预测反应器中每一级的气含率和循环液速的流体力学模型,模型预测值与实验结果吻合较好。 相似文献
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利用计算流体力学(CFD)数值模拟方法.采用Euler法双流体模型研究了表观气速对气液两相气升式环流反应器的液体循环速率和气含率的影响.实验结果与数值模拟结果吻合较好.结果表明.气含率和液体速率在反应器内分布不均匀,气含率在相同的径向位置变化很小,液体速率随着表观气速的增加而增加. 相似文献
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气升式环流反应器在不同体系下的循环液速和局部气含率 总被引:12,自引:1,他引:12
在气升式环流反应器中,分别研究了空气—水、空气-0.1%乙醇水溶液和空气-水-活性污泥体系中的循环液速以及气含率随操作条件的变化规律。实验结果表明,循环液速随着表观气速的增加而增大,不同体系中的循环液速差别不大;导流筒内、外不同高度处的局部气含率均呈自下向上增大的趋势,且导流筒内部气含率高于导流筒外部的气含率。体系的聚并特性对平均气含率和局部气含率有较大影响。 相似文献
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外环流反应器的气含率及循环液速 总被引:9,自引:0,他引:9
研究了气体分布器的形式、体系的聚并特性及静液面高度对外环流反应器的气含率和环流液速的影响。实验结果显示,对于空气-1%乙醇体系(非聚并体系),气体分布器的形式对外环流反应器的气含率及环流液速有显著的影响;在相同的操作条件下,空气-1%乙醇体系(非聚并体系)的气含率及环流液速明显高于空气-水体系(聚并体系)。静液面高度对下降区的气含率有较大影响。 相似文献
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在空气-水-石英砂三相多室气升式环流反应器(MALR)中,调节底部转角连接处间隙高度分别为18,28,38mm,在表观气速1.2~4.2cm/s范围内,实验研究了底部阻力系数、相含率、循环液速随反应器底部间隙的变化规律。结果表明,随着底部间隙的增大,底部转角处的局部阻力系数减小,循环液速增大,流体夹带进入下降室的气泡和固体颗粒均增多,下降室的气含率和固含率均增大。 相似文献
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研究了气速、液速对喷射式环流反应器气-液传质比表面积以及全塔、导流管和环隙部分的平均气含率的影响。提出将喷射式环流反应器中传递性能参数随操作条件的变化规律进行分区研究可简化放大过程。根据实验数据和文献数据,获得了计算敏感区域全塔平均气含率(?)和气液传质比表面积a_R的关联式: (?)=7.18×10~(-4)U_g~(0.55)Re_1~(1.24)D~(-0.64) a_R=644U_(g)~(0.44)(ρ_L/V_R)~(0.46) 相似文献
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气升式外环流反应器的体积传质系数 总被引:1,自引:0,他引:1
以Higbie的渗透理论和Kolmogoroff的湍流理论为基础,提出了计算液体旋涡在气液相界面暴露时间的方法,并建立了预测体积传质系数的模型方程。在不同管径比下的外环流反应器中,对空气 水体系测定了操作气速对体积传质系数、循环液速和气含率的影响。将体积传质系数与表观气速和下降管与上升管的面积比按幂函数进行关联,其预测值和试验值符合较好。 相似文献
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Qiang Li Xuebing Zhao Keke Cheng Wei Du Dehua Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(4):704-710
BACKGROUND: The classical airlift loop reactor (ALR) has been widely used in petrochemical, biochemical, energy and environmental processes due to such advantages as simple structure, without motional mechanism, easy sealing and low energy consumption. A novel ALR has been designed using forced periodic reversible ventilation, termed an airlift reversible loop reactor (ARLR). RESULTS: Using computational fluid dynamics (CFD) simulation and experimental validation, the mass transfer characteristics of the ARLR were studied. The simulation results predicted the experimental data well, especially at low ventilation capacity. The oscillation period had significant effects on gas holdup and the mass transfer coefficient of the ARLR. When ventilation capacity was increased from 0.22 to 3.49 vvm, compared with central airlift and annular airlift reactors, ARLR increased the mass transfer coefficient by 9–31% and 10–58%, respectively, according to simulation results, and by 11–25% and 14–58%, respectively, according to experimental data. CONCLUSION: The results showed that the ARLR could significantly enhance gas holdup and mass transfer coefficient compared with traditional central airlift and annular airlift reactors. Results indicated that the optimum oscillation period decreased with increase of ventilation capacity. ARLR has the potential for application in aerobic fermentation. © 2012 Society of Chemical Industry 相似文献
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The helical flow promoter (HFP), inserted in the downcomer of an airlift reactor (ALR), generates a helical flow pattern in the circulating gas–liquid (solid) mixture. Data on the fluidization capacity, gas holdup, liquid velocity and mass transfer rate for two- and three-phase systems with two different carboxymethylcellulose solutions collected in a 58 L ALR-HFP are presented and compared with those of common pneumatic reactors. Generally, an increasing solid concentration led to a slight decrease in gas holdup and liquid velocity but to a considerable decrease in mass transfer rates. Insertion of HFPs produced a significantly enhanced fluidization capacity of solid particles compared to the common systems. 相似文献
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由于环流反应器内存在定向循环,与鼓泡塔反应器相比,其混合性能大幅提升,已广泛应用于许多工业过程,如发酵、反应器结晶等工业过程,近年来成为国内外学者研究的热点。针对环流反应器内操作条件下的流动形态、流体力学(包括相含率分布、循环液速、混合时间以及离集指数等)及传质/传热特性,总结了其最新研究进展,分析了相含率尤其是固含率变化对反应器中关键参数如循环液速和化学反应速率的影响,展望了从机理上研究相互耦合的多相流动、传质/传热和化学反应规律,为进一步推动其工业应用提供参考。 相似文献
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The radial profiles of axial liquid velocity and gas hold‐ups are investigated in the riser of a pilot plant scale external loop airlift reactor (ELAR) using a modified Pavlov tube and differential pressure technique. The experimental investigation reveals that there exist two different kinds of liquid circulation structures in an ELAR, which has rarely been reported in the literature, namely internal liquid circulation, which exists only in the riser and external liquid circulation, which circulates through the downcomer. A power–law relationship is used to correlate the gas hold‐up and superficial gas velocity, which gives good agreement with experimental data. Experiments for axial liquid velocity profiles are analysed in analogy to a model described for a conventional bubble column. The results predicted by the model are in excellent agreement with the experimental data obtained under various operating conditions. © 2011 Canadian Society for Chemical Engineering 相似文献
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利用计算传质学方法对内循环气升式环流反应器(ILALR)内生物降解苯酚废水过程进行了研究。采用欧拉多相流模型结合RNG k-ε湍流模型对ILALR中气-液两相流动过程进行模拟,采用气泡群平衡模型(PBM)对反应器内气泡的尺寸分布进行预测。利用近年来提出的计算传质学 -εc模型对湍流扩散系数进行计算,从而摆脱了传统需要预估湍流Schmidt数的经验方法。模拟得到的液相苯酚和菌体浓度与实验测量值吻合良好,从而证明了所建立模型的有效性。研究结果表明ILALR内湍流传质过程中湍流扩散系数及湍流Schmidt数并非常数,因此基于传递相似性假设得到的湍流Schmidt数经验模型不适用于ILALR内湍流传质过程的模拟。模拟得到的ILALR中液相剪应力随表观气速的增大而增大,局部最大值出现在导流筒的上部。 相似文献