滴流床中的气液传质

本文提出了同时估算滴流床内气液传质系数和持液量的阶跃响应S域分析法,着重讨论了液体表面张力对床内气液传质系数的影响,并给出了计算床内气液传质系数和持液量的关联式。     

小颗粒滴流床反应器的流体力学研究

在内径为０．０４７ｍ，床层高０．７ｍ的滴流床反应器内，采用空气－水－玻璃珠（１．８，３．１８ｍｍ）体系，在常温、常压下进行实验。气、液流速分别在０．０５４－０．２３ｋｇ／（ｍ＾２ｓ）和３．２０－１４．７３ｋｇ／（ｍ＾２ｓ）内，用电导信号脉动法、压降波动法结合目测法测定了滴流床的流动状态及其变化，实验结果可用于确定不同操作条件下的流动状态。本研究还分别是用差计、示踪剂法和体积法对滴流床的压降，总持流     

滴流床小颗粒催化剂滴流区和脉动流区传质的研究

本文研究了滴流床小颗粒催化剂在滴流区和脉动流区的气相容积传质系数k_Gα,气液接触有效界面积“α”和脉动流形成时分散气泡的平均直径d_b。实验表明:不同流区的传质与流型和流动介质的能量损失有关。强化传质会增加流动介质的能量消耗及减小催化剂粒度。     

滴流床反应器的压降和持液量

在空气、水和固体玻璃或陶瓷球颗粒床层中,测定了两相并流时的压降和持液量。讨论了流体流率、颗粒粒度及材质对压降和持液量的影响,比较了大颗粒和小颗粒的特性,修正了前人的一些关联式。     

滴流床式固定化植物细胞反应器中的压降和持液量

滴流床式固定化植物细胞反应器中的压降和持液量袁丽红，周名立，欧阳平凯（南京化工学院应用化学系，南京２１０００９）关键词：滴流床反应器，固定化植物细胞，压降，持液量１前言植物细胞的固定化通常采用海藻胶进行包埋，然后源源不断地提供其营养成分并通入空气，以...     

Gas‐Liquid Mass Transfer in a Bench‐Scale Trickle Bed Reactor used for Benzene Hydrogenation

The gas‐liquid mass transfer coefficients (MTCs) of a trickle bed reactor used for the study of benzene hydrogenation were investigated. The Ni/Al₂O₃ catalyst bed was diluted with a coarse‐grained inert carborundum (SiC) particle catalyst. Gas‐liquid mass transfer coefficients were estimated by using a heterogeneous model for reactor simulation, incorporating reaction kinetics, vapor‐liquid equilibrium, and catalyst particle internal mass transfer apart from gas‐liquid interface mass transfer. The effects of liquid axial dispersion and the catalyst wetting efficiency are shown to be negligible. Partial external mass transfer coefficients are correlated with gas superficial velocity, and comparison between them and those obtained from experiments conducted on a bed diluted with fine particles is also presented. On both sides of the gas‐liquid interface the hydrogen mass transfer coefficient is higher than the corresponding benzene one and both increase significantly with gas velocity. The gas‐side mass transfer limitations appear to be higher in the case of dilution with fine particles. On the liquid side, the mass transfer resistances are higher in the case of dilution with coarse inerts for gas velocities up to 3 · 10^–2 cm/sec, while for higher gas velocities this was inversed and higher mass transfer limitations were obtained for the beds diluted with fine inerts.     

Liquid/Solid Mass Transfer in Fixed Beds

The liquid/solid mass transfer behavior of a fixed bed of cylinders was studied using the diffusion‐controlled dissolution of copper in acidified potassium dichromate. Variables studied were solution velocity and cylinder diameter. For a steady flow, the data were correlated for the conditions 25 < Re < 600 and Sc = 990 by the equation Sh = 2.65 Sc^0.33 Re^0.5. A comparison between the present data and previously obtained data for a fixed bed of Raschig rings has revealed that cylinder packing produces higher rates of mass transfer than Raschig rings.     

滴流床中液体流动的随机模型

本文以状态离散、时间离散的齐次Markov过程描述滴流床内液体的滴流与脉动流流动,提出了可直接计算任一床层高度上液体的流率分布和极限流率分布的方法和计算式。推导出了随机堆积球型颗粒床层中液体流动的转移概率矩阵。计算结果表明,本文模型计算值与实验值吻合较好。     

Study of Single Phase Flow Heat Transfer and Friction Pressure Drop in a Spiral Internally Ribbed Tube

The experimental results of single‐phase flow heat transfer and pressure drop experiments in the turbulent flow regime in a spirally ribbed tube and a smooth tube are presented in this paper. The ribbed tube has an outside diameter of 22 mm and an inside diameter of 11 mm (an equivalent inside diameter of 11.6 mm) and the smooth tube has an outside diameter of 19 mm and an inside diameter of 15 mm. Both tubes were uniformly heated by passing an electrical current along the tubes with a heated length of 2500 mm. The working fluids are water and kerosene, respectively. The experimental Reynolds number is in the range of 10⁴–5 · 10⁴ for water and is in the range of 10⁴–2.2 · 10⁴ for kerosene. The experimental results of the ribbed tube are compared with those of the smooth tube. The heat transfer coefficients of the ribbed tube are 1.2–1.6 fold greater than those in the smooth tube and the pressure drop in the ribbed tube is also increased by a factor of 1.4–1.7 as compared with those in the smooth tube for water. The corresponding values for kerosene are 2–2.7 and 1.5–2, respectively. The heat‐transfer enhancement characteristics of the ribbed tube are assessed. This tube is especially suitable for augmenting single‐phase flow heat transfer of kerosene. Correlations for the heat transfer and the pressure drop for the spirally ribbed tube are proposed, according to the experimental data.     

Intensification of Deep Hydrodesulfurization Through a Two-stage Combination of Monolith and Trickle Bed Reactors

Deep hydrodesulfurization (HDS) is an important process to produce high quality liquid fuels with ultra-low sul-fur. Process intensification for deep HDS could be implemented by developing new active c...     

Local Structure Effects on Pressure Drop in Slender Fixed Beds of Spheres

For slender fixed beds, the void fraction and flow properties are complex topics. Different factors can influence the local bed structure. For statistical analysis, 2800 fixed beds have been generated and the impact of friction factor and reactor-to-particle diameter ratio on the distribution has been shown. With particle-resolved computational fluid dynamics, all local structure effects are taken into account for the flow simulations. Pressure drop measurements and simulations showed that these effects can lead to areas with low flow resistance, leading to overestimated pressure drop by typical correlations up to 85 %.     

Mass Transfer In Trickle‐Bed Reactors With Structured Packing

An experimental investigation was carried out to examine the fluid dynamic and mass transfer behavior of structured packing, with the liquid and gas phase flowing co‐currently downwards in the column. Liquid to packing mass transfer coefficients for three positions within the pack were measured by an electrochemical method, varying both the liquid and gas loads as well as the physical properties of the liquid phase. Due to the high void fraction of structured packing, much higher liquid flow rates can be used than in traditional particle trickle‐beds. It was found that in the range studied, the gas superficial velocity has no effect on the mass transfer rate and thus, a general mass transfer correlation in terms of liquid Reynolds number only, was developed. Wetted areas and the radial distribution of liquid through the packing element were determined by a colorimetric method. Within the range of liquid flow rates investigated, complete wetting is not achieved, even with the low viscosity solutions. The measured ratios of hydraulic to geometric area, agree reasonably well with values predicted by existing relationships.     

Pressure Drop and Mass Transfer Study in Static Mixers with Gas Continuous Phase

The aim of this work was to characterize both the influence of the gas and the liquid flow rates on the pressure drop generated by static mixers type Sülzer, and on the mass transfer performances of these gas‐liquid contactors. The originality of this work rests on the use of the static mixers with a gas continuous phase. Several configurations were studied: vertical upward flow, vertical downward flow, and horizontal positions, with one to five mixing elements. It was concluded that the pressure drop is mainly generated by the gas phase, whatever the configuration chosen. Moreover, the volumetric mass transfer coefficients k_La found were lower than those obtained with the same static mixers used in classic conditions (that is with a liquid continuous phase), but greater than values obtained with classic reactors like bubble columns or packed columns. The efficiency of these gas‐liquid reactors was found high, as well as the energy dissipated, unfortunately.