气升式环流反应器的研究进展

环流反应器在工业上正得到越来越广泛的应用,对其进行深入研究对于此类反应器的设计与放大具有重要意义。对环流反应器的流动、混合及传质特性参数随表观气速、液相物性、系统压力和反应器尺寸等操作条件的变化关系进行了综述。介绍了各特性参数的测量方法,并指出了这些方法的优缺点及可能存在的误差。对环流反应器的流动、混合及传质特性的数学模型进行了评述,并在此基础上对环流反应器研究的发展前景进行了展望。     

气升式环流反应器的研究进展

就气升式环流反应器的类别、操作条件和几何结构对环流反应器内两相流体力学行为的影响规律进行了评述。根据环流反应器的流体力学特性和传质特性指出了环流反应器的应用领域及要求。列举了环流反应器在工业上的应用实例。     

大型加压环流反应器的冷模试验

环流反应器结构简单,优点多,因而近年来应用广泛。为了将环流反应器引入煤炭液化领域,建立了大型环流反应器冷模试验装置。进行了氮气-水体系的冷模运转试验,考察了表观气速、压力和表面张力对环流反应器中气含率的影响。在此基础上,对鼓泡状态和环流状态下的气含率进行了比较,并考察了环流反应器的操作弹性,得出了有重要意义的结论。     

大型加压环流反应器局部气含率及气泡行为研究

为了将环流反应器引入煤炭液化领域,建立了大型环流反应器冷模试验装置.进行了氮气一水体系及其他体系的冷模运转试验,对环流反应器内小同部位的局部气含率进行了比较分析,并考察了压力和气体密度的影响.对反应器内的大小气泡上升速率进行了尝试汁算,得出了有重要意义的结论.     

用于微生物石油脱蜡的新型气升环流反应器

本文报导了一种新型气升环流反应器,对反应器中液相流型、气含率与操作条件之间的关系进行了实验考察。利用气升环流反应器强化传质和混合的原理,将一个100m^3鼓泡塔反应器改造成三管循环的气升环流反应器,发酵试验结果表明气升环流反应器微生物脱蜡周期比原鼓泡反应器缩短4倍,气升环流反应器能耗比鼓泡反应器降低约30％。     

气升式环流反应器特性参数的研究进展

介绍了气升式环流反应器的工作原理、分类及流型,综述了气升式环流反应器的流体力学特征参数(主要包含气含率和循环液速)、混合及传质特性参数的测量方法和影响因素。介绍了气含率和循环液速的数学模型,并评述了现有模型。展望了气升式环流反应器进一步的研究方向与发展前景。     

气升式环流反应器特性参数的研究进展

介绍了气升式环流反应器的工作原理、分类及流型,综述了气升式环流反应器的流体力学特征参数(主要包含气含率和循环液速)、混合及传质特性参数的测量方法和影响因素。介绍了气含率和循环液速的数学模型,并评述了现有模型。展望了气升式环流反应器进一步的研究方向与发展前景。     

气升式振荡环流反应器的数值模拟和结构优化

气升式振荡环流反应器（ARLR）作为一种新型的气升式环流反应器,能够有效地提高反应器的气含率和传质系数,并已得到生物发酵实验的验证。本文通过CFD的手段研究了反应器内的流动和传质状况,并利用CFD模拟和响应面分析相结合的方法,优化了反应器的结构参数,如高径比（H/D）、升液区降液区面积之比、导流筒高度等。经过实验测量,优化后的气升式振荡环流反应器与传统的气升式环流反应器相比,气含率提高了32%以上,传质系数提高了11%以上。结果表明,气升式振荡环流反应器作为生化反应器有着非常广阔的应用空间。     

反应器类型对流动影响的数值模拟

在油-氢气体系中使用欧拉-欧拉双流体模型考察了温度703.15 K和压力11 MPa下气升式环流反应器和鼓泡床反应器对气液两相流动的影响. 结果表明,环流反应器中气含率和轴向液速沿导流筒径向存在突增现象,环流反应器中气含率在径向0~0.5和0.75~1时明显大于鼓泡床反应器,在径向0.5~0.75处前者的平均气含率比后者高约6%;环流反应器中上升管内环流液速明显大于鼓泡床反应器,且在下降区有所增强,环流反应器平均轴向液速比鼓泡床反应器高约21%;反应器尺寸较小时环流反应器和鼓泡床反应器的流动特性相差不大,反应器体积放大过程中前者的流动特性优于后者的趋势逐渐明显.     

新型多级环流反应器流体力学研究

在传统的单级内环流反应器的基础上,对导流筒进行了改进,发展了一种新型多级环流反应器。研究了表观气速、开孔率、反应器底部结构等操作参数对整体平均气含率、局部气含率以及各级环流液速等流体力学行为的影响,从而确定了反应器的最佳结构。文中提出的新型多级环流反应器在石油化工、生物化工和环境工程等多个领域有广泛的应用前景。     

环流反应器研究现状

环流反应器靠气相浮力和液相动能来实现反应器内规则的循环流动,具有不需要附设循环泵和机械搅拌装置等优点,文章对近几年环流反应器气含率、混合和传质的影响因素、测量方法和模型作了总结,并对进一步研究方向进行了展望。     

Liquid flow texture analysis in trickle bed reactors using high-resolution gamma ray tomography

Trickle bed reactor performance and safety may suffer from radial and axial liquid maldistribution and thus from non-uniform utilization of the catalyst packing. Therefore, experimental analysis and fluid dynamic simulation of liquid–gas flow in trickle bed reactors is an important topic in chemical engineering. In the present study for the first time a truly high-resolution gamma ray tomography technique was applied to the quantitative analysis of the liquid flow texture in a laboratory cold flow trickle bed reactor of 90 mm diameter. The objective of this study was to present the comparative analysis of the liquid flow dynamics for two different initial liquid distributions and two different types of reactor configurations. Thus, the hydrodynamic behavior of a glass bead packing was compared to a porous Al₂O₃ catalyst particle packing using inlet flow from a commercial spray nozzle (uniform initial liquid distribution) and inlet flow from a central point source (strongly non-uniform initial liquid distribution), respectively. The column was operated in downflow mode at a gas flow rate of 180 L h⁻¹ and at liquid flow rates of 15 and 25 L h⁻¹.     

78.5升气升式环流反应器内构件优化

研究了78.5L气升式环流反应器内部结构对流动性能的影响规律, 并给出最佳区间来为工业装置提供理论指导。利用Fluent软件建立数学模型与实验装置作对比, 模拟了不同气液分离区高度与外筒高度比、导流筒长度与外筒长度比和筒内外直径比对流动行为的影响规律。结果表明:数学模型和实验结果误差较小, 可以用来预测气升式环流反应器流动行为。气液分离区高度与外筒高度比值过大会导致环流阻力增大, 从而不利于流动, 比值为0.34~0.36时流动性能最佳;导流筒长度与外筒长度的比值增大可增加气含率和环流液速, 但是比值过大会引起气泡的聚合, 从而影响流动性能, 当比值为0.60~0.62时流动性能最佳;在一定范围内增加内外筒直径比会改善流动效果, 但环隙面积过小会增加环形阻力, 内外筒直径比为0.73~0.77时流动效果比较理想。     

Modulation of liquid holdup along a trickle bed reactor with periodic operation

Temporal variations of the liquid holdup in a mini-pilot scale trickle bed reactor cold-mockup, induced by an ON-OFF liquid flow modulation strategy of operation, are explored at different axial positions. The reactor is packed with porous beads of γ-Al₂O₃ and the liquid holdup is approximately estimated with a conductimetric technique, using probes that mimic the packing. The effects of the liquid and gas superficial velocities, the bed depth and the cycling parameters, cycle period and split, on the liquid holdup modulation are examined for a wide range of conditions. For slow and intermediate cycle periods, the liquid holdup time dependence observed during the dry period is represented by an exponential function. The characteristic value of the decay is correlated to the examined variables. The correlation allows reconstruction of the liquid holdup time dependence along the column.     

Effects of reactors on the deposition of DLC films using liquid electrochemical technique

Carbon films were deposited on silicon substrates by liquid electrochemical technique at low temperature (60 °C) in ambient atmosphere. Glass reactor, glass reactor with PTFE-coating inside, glass reactor with quartz-coating inside and quartz reactor were used with the same experimental setup to compare the effects of reactors on the deposition of carbon films. The applied potential, the distance between anode and substrate and the deposition time were fixed at 900 V (4.2 kHz, 50%), 6 mm and 5 h, respectively. The morphology and microstructure of the films were analyzed by scanning electron microscopy (SEM) and Raman spectroscopy. Energy Dispersive X-ray Spectrometry (EDX) was used to measure the composition of the films. The SEM observations showed that the films deposited using glass reactor were composed of crystals of several micrometers which contained nearly 10 at.% of Ca. Raman spectroscopy analysis confirmed that DLC films have been deposited, but with an obvious sharp peak at 1085 cm^− 1 which is assigned to calcium carbonate (CaCO₃) crystals. The glass reactor is the possible source of Ca because the electrolyte was composed of analytically pure acetone and deionized water with the proportion of Ca below the determination of AAS (atomic absorption emission spectrophotometer AA-6200). Using glass reactor with PTFE-coating inside could successfully avoid the impurity of Ca from the glass reactor, but new non-metallic impurities coming from the PTFE-coating made the films rough. Continuous and smooth films were deposited by using a glass reactor with quartz-coating inside and quartz reactor, which could avoid both Ca (< 1 at.%) and other impurities. Raman spectroscopy analysis confirmed typical DLC films without CaCO₃. It can be concluded that the materials of the reactors could play an important role not only in the composition, but also the morphology and microstructure of films deposited by liquid electrochemical technique.     

多层百页窗式挡板三相流化床中液相混合行为

采用脉冲应答技术测定了矩形气液固三相流化床反应器中液相混合时间和下降速度。考察了挡板结构、气液流量、固体浓度对床层液相混合行为的影响。实验结果表明，在床中设置挡板构件，对液体混合时间与液体下降速度的影响不明显。     

BACK MIXING AND LIQUID HOLD-UP IN A COCURRENT UP-FLOW PACKED BED BIOREACTOR

The hydrodynamics of an up-flow three phase packed bed bioreactor were investigated experimentally using tracer techniques. The effects of the liquid and gas velocities, and the particle size on the Peclet number (Pe) and on the liquid hold-up (ε_L) were determined. While the range of gas and liquid flow rate were chosen according to biotic conditions. It was found that the Pe was not influenced from liquid flow rate, however decreased with increasing gas flow rate and particle/reactor diameter ratio (d_p/D_c). Also, it was found that liquid hold-up was not influenced from gas flow rate, however increased with increasing liquid flow rate and decreased with increasing d_p/D_c ratio. The correlation which connected the Bodenstein number to gas phase particle Reynolds number and d_p/D_c ratio and the correlation which connected the liquid hold-up, liquid phase particle Reynolds number and d_p/D_c ratio were found using Marquardt-Levenberg approach.     

Hydrodynamics and flow regime transition study of trickle bed reactor at elevated temperature and pressure

The hydrodynamics in a trickle bed reactor (TBR) in non-ambient conditions are studied for air-water and air-acetone (pure organic liquid of low surface tension) systems. A flow map experiments for air-water and air-acetone systems are performed in a pilot plant reactor of 0.05 m i.d. and 1.25 m height. It has been demonstrated from the experimental results that the pressure drop tends to increase with increasing superficial gas and liquid velocity and reactor pressure, while it tends to decrease with increasing bed temperature. The results also show that the dynamic liquid holdup increases with increasing liquid velocity and decreases with increasing superficial gas velocity, reactor pressure and bed temperature. The dynamic liquid holdup and pressure drop values are obviously higher than those measured for air-water system at the same fluid fluxes, reactor pressure and bed temperature due to the surface tension effects. For higher reactor pressure and temperature, the trickle to pulse transition boundary shifts towered higher superficial velocities of both gas and liquid.     

Slow-mode gas/liquid-induced periodic hydrodynamics in trickling packed beds derived from direct measurement of cross-sectional distributed local capacitances

Hydrodynamics of a periodically operated trickling packed bed was studied with a high-speed wire-mesh sensor technique based on direct measurement of cross-sectional distributed local capacitances. Liquid cycles in the alumina packing were generated by periodic induction of gas and/or liquid phase in distinctive slow-mode. Hydrodynamics were characterized with respect to liquid saturation and liquid saturation distribution varying period length, split and time-averaged superficial gas and liquid velocities. The sensors technique allows direct access to local phenomena during liquid pulse breakthrough, to distribution patterns and their reproducibility at different cycle positions that were studied based on transient liquid saturation distribution data of different periodicity variables. Due to simultaneous measurement at four different axial reactor positions, pulse attenuation along the reactor and pulse velocity could be analyzed. Furthermore, hydrodynamics of different modes of gas-induced periodic cycling, e.g. gas cycling only, asynchronous and synchronous cycling of gas and liquid flow rate and alternating gas–liquid cycling, were studied.     

环流反应器流体力学参数测定技术研究

介绍了环流反应器流体力学参数的测定方法,这些参数包括气含率、循环液速、固含率、气泡大小及速度。综述了这些参数测量方法的原理、设备及优缺点,评价了它们目前的发展状况及动向,提出了参数测定方法今后工作的重点,对于环流反应器的流体力学研究具有重要的指导意义。