Characterization of New Wire Gauze High‐Capacity Structured Packing with Varied Inclination Angle

A new high‐capacity structured packing (PACK‐1300) was investigated for the separation of mixtures with low separation factor. The effect of the inclination angle was studied. In order to enhance the pressure drop and the separation efficiency of PACK‐1300, the surface area and porosity were increased. In addition, comprehensive parametric studies were performed to evaluate the dry/wet pressure drop and mass‐transfer efficiency under various operating conditions. Increasing the inclination angle enhances the capacity and decreases the efficiency of the packings. PACK‐1300W reduced the dry and wet pressure drop significantly more than PACK‐1300Z. Finally, the separation efficiency results show that the height equivalent to a theoretical plate decreased with decreasing inclination angle.     

Characterization of a New Structured Packing by Computational Fluid Dynamics

The novel wire gauze structured packing PACK‐1300Y with high specific surface area was characterized by computational fluid dynamics. The main features of PACK‐1300Y were investigated including the dry and wet pressure drop as well as the height equivalent to a theoretical plate (HETP). Moreover, the flow structure of this packing was described via numerical simulations. To evaluate the amount of HETP and dry and wet pressure drop, 3D computational fluid dynamic modeling with respect to the Eulerian‐Eulerian multiphase approach was applied. The average relative errors were determined between the findings achieved from computational fluid dynamic simulation and experimental findings for mass transfer efficiency and wet and dry pressure drop, respectively.     

Mass transfer characteristics of liquid films flowing down a vertical wire in a counter current gas flow

The wetted-wire packing, mainly consisting of a bundle of vertical parallel wires, is a promising concept for the use in separation columns. To investigate the multiphase flow inside the packing in detail and to estimate the performance of the packing, experiments on liquid films on a single vertical wire in a counter current gas flow were carried out. To get information about the interfacial area, an optical measurement of the film thickness was carried out with a digital high speed camera and image recognition tools. By measuring the evaporation of water and aqueous polyvinylpyrrolidone solutions into air, the gas-side mass transfer was determined. The liquid-side mass transfer was examined by measuring the desorption of CO₂ from water into air. The results show that the mass transfer coefficients are comparable to those appearing in common structured packings. When assuming a sufficiently high wire packing density, a specific interfacial area similar to corrugated sheet structured packings can be reached. Previous studies predicted a low pressure drop per packing height and extended capacity limits compared to common packings. In consideration of these results, the wetted wire packing therefore is shown to be suitable especially for absorption processes where a low pressure drop is favourable.     

Liquid‐bridge flow in the channel of helical string and its application to gas–liquid contacting process

To solve the problems of the traditional packings, such as high pressure drop, mal‐distribution and short liquid residence time, a helical flow structured packings was proposed. Two different flow patterns, liquid‐bridge flow and liquid‐drop flow were identified when the width of the channel of the helical string was adjusted. Moreover, the characteristics of the helical liquid‐bridge flow including maximum liquid loading, mean thickness of liquid film, mean residence time and effective specific surface area, were examined. And the separation efficiency was studied by the lab‐scale distillation column. In comparison, the effective specific surface area of the helical flow type packings is almost as large as the traditional B1‐350Y structured packings, but with thinner liquid film, longer liquid residence time and finally higher separation efficiency. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3360–3368, 2018     

液相流动方式对波纹规整填料性能的影响

根据液相在波纹规整填料片上呈现渗流、膜状流等不同的流动方式,选择5种不同的波纹规整填料对其流体力学和传质性能进行研究,以探究液相在波纹片上的流动方式对波纹规整填料性能的影响.研究结果表明,液相呈渗流流动的泡沫碳化硅波纹规整填料(SCFP型)有利于液体横向扩散和液膜均匀分布,当液相喷淋密度和气相F因子均较小时,其压降最低,传质效率最高;液相主要呈渗流流动、兼有膜状流动的双层错孔丝网填料(DMⅢ型)有利于波纹片两侧液体交换,强化液体在流动过程中的扰动,其压降及传质性能略逊于SCFP型填料;液相主要呈膜状流动的BX型、DMⅠ型及DMⅡ型填料波纹片表面液膜较厚,横向扩散能力差,其传质效率低于SCFP型和DMⅢ型填料.研究揭示了依靠渗流作用的波纹规整填料具有较好的应用性能,为波纹规整填料的进一步发展开拓了新思路.     

新型垂直板规整填料流体力学及传质性能

采用氧解吸实验,在直径190 mm的有机玻璃塔内,液相喷淋密度10～38 m³·m^-2·h^-1,F因子0.2～3.2 m·s^-1·（kg·m^-3）^0.5的实验条件下测定了一种新型垂直板规整填料的流体力学及传质性能。实验结果表明：垂直板填料的操作压降及传质性能均显著优于商业波纹填料。通过与几种经改进的250型波纹填料相比发现,两者泛点F因子整体上相当;在较高液体喷淋密度下,垂直板填料传质性能及压降均高于改进250型波纹填料;在低喷淋密度下,垂直板填料可实现压降低于改进250型波纹填料,而两者传质性能相当。此外,对填料结构改进对其性能的影响进行了单因素考察。     

规整丝网填料旋转填充床的气相压降特性及脱硫性能

采用空气-水体系,对装有4种不同规格规整丝网填料的旋转填充床的压降特性进行了实验研究,考察了转速、气体流量、液体流量等操作参数及填料特性对气相压降的影响规律,并与传统不锈钢波纹丝网填料旋转填充床压降进行了比较. 结果表明,装有规整丝网填料的旋转填充床压降可降低35%~70%. 进一步采用压降较低的规整丝网填料以(NH4)2SO3为吸收剂进行氨法脱硫性能研究,结果表明,随转子转速和(NH4)2SO3浓度增大,SO2脱除率升高;随进气口SO2浓度升高及气液比增大,SO2脱除率降低;SO2脱除率最高可达97%,可满足国家排放标准.     

新型高效规整填料的性能研究

为了获得可靠的设计依据,实验在不同回流比条件下,用环己烷-庚烷和庚烷-甲苯2种二元测试物系对CDG1700Y和CDG2500Y型金属丝网规整填料的流体力学性能和传质性能进行了考察。实验结果表明,这2种填料的压降随着液体流量的增大而增大,单位填料层高度的HETP变化趋势则相反;CDG1700Y和CDG2500Y型填料具有较高的理论板数,且CDG1700Y型填料具有较大的操作弹性。在SRP(II)模型的基础上,获得了实验室条件下传质单元高度的经验关联式,其计算值与实验结果吻合较好,可以为化学交换法分离硼同位素的工业化提供理论指导。     

Liquid film flow on structured wires: Fluid dynamics and gas‐side mass transfer

The liquid film flow on different structured wires and chains is observed experimentally to assess the suitability of a structured packing consisting of vertical wires. The results show that liquid beads as they appear on cylindrical wires are inhibited by certain chain geometries. This increases the flooding gas load up to F = 12 Pa^0.5. As the stabilized film shows no liquid bead motion, the liquid velocity at the interface is less which results in lower gas‐side mass‐transfer coefficients. An estimation of the packing characteristics for different chain geometries with an assumed wire packing density of 40,000 wires/m² is made. The interfacial area, mass‐transfer coefficients, and consequently the separation efficiency strongly depend on the liquid load. However, the proposed gas‐side separation efficiencies are slightly lower compared to common structured packings but the advantages are higher load limits, a better liquid distribution, and lower pressure drop. © 2012 American Institute of Chemical Engineers AIChE J, 59: 295–302, 2013     

Comparative study of dry pressure drop and flow behaviour of gas flow through sieve plate packing

Sieve plate packing is a newly developed packing that has been used in several industries due to its simple structure and operating flexibility, and no liquid flooding. In this work, first, systematic experiments were conducted to measure the pressure drop of gas flow through six sieve plate packings. The results indicated that the geometric characteristics of the packing have complicated effects on the pressure drops. Based on this, CFD simulations on the gas flow field were conducted using the realizable k-ε model, and flow behaviours such as the pressure drop, pressure nephogram, and velocity distributions within different packings were obtained. The simulation results clearly showed interesting flow patterns, including the contraction and expansion of the gas stream through the sieve hole, the flow separation on the sharp edge of the hole, and the vortexes formed when gas impacts the downstream plate. By comparing the flow patterns and the pressure drop under different packings operating at different conditions, the effects of the geometric characteristics of the packing on the pressure drop could be clearly distinguished from the flow behaviours, so that the variations in pressure drop with various packing structures were clearly indicated. Finally, based on the experimental data and the simulated results, correlations for the prediction of the pressure drops were proposed. This work will provide a useful basis for understanding the flow behaviour of gas and liquid two-phase flow in sieve plate packing.     

Holdup and Pressure Drop of Packed Beds Containing a Modular Catalytic Structured Packing

A comparative experimental study has been carried out to establish the hydraulic behavior of a new modular catalytic packing (Sulzer's Katapak^®‐SP 12) and the hybrid packed bed consisting of a catalytic packing section placed in between two sections comprising elements of a high capacity structured packing (MellapakPlus 752.Y). Air‐water experiments were carried out at ambient conditions using a Perspex column with an internal diameter of 0.45 m. As expected, the liquid holdup and the pressure drop of the combined bed were between those measured for beds consisting purely of the catalytic and structured packings. However, unlike the two reference beds, the combined bed exhibited a clear upper gas load limit due to a pronounced liquid buildup at the transition from the structured packing to the top element of the catalytic packing section. Also it appeared that the Delft model, with appropriate packing geometry modifications is capable of reliably predicting the preloading region holdup and pressure drop of a hybrid packed bed containing Katapak‐SP.     

Experimental Investigation of the Froth Height in Columns with Sandwich Packings

Sandwich packings, consisting of alternatingly stacked conventional structured packings with different geometric surface areas, are promising for increasing capacity and efficiency of separation columns. Film flow and froth flow evolve along a stack, which requires comprehensive fluid dynamic analysis. In particular, the froth height is an essential parameter to determine the spatial extent of the flow regimes. Ultrafast X‐ray tomography and a 3D‐printed pressure drop profile measurement module were applied to independently estimate this parameter. The results are compared with existing correlations.     

CFD Studies of Pressure Drop and Increasing Capacity in MellapakPlus 752.Y Structured Packing

Packed columns equipped with structured packings are widely used in separation processes. In this study, the hydrodynamics of MellapakPlus 752.Y was investigated using a computational fluid dynamics (CFD) approach. This packing includes short smooth bends at both ends of each corrugated sheet. Two adjacent sheets of a whole packing module were considered as computational domain. The CFD results indicated that the gas phase should be simulated using a turbulent model for F factors higher than 0.8. Thus, various two‐equation turbulence models were evaluated for the gas phase in the CFD model. It was shown that the baseline k‐ω (BSL) model leads to a slightly improved prediction of the pressure drops compared with the experimental data. The effects of the bends on the structured packing were studied by the model. It was found that using bends in the packings is useful for increasing the capacity and decreasing the pressure drop of the systems.     

CFD‐assisted Characterization and Optimization of the Structured Mass Transfer Packing QVF DURAPACK®

The glass packing QVF DURAPACK® was developed to use the advantages of structured mass transfer packings, especially when handling corrosive media. To match up with the latest developments for sheet metal packings, further optimization for liquid‐liquid separation processes was performed for the QVF DURAPACK®. The complex geometry of structured packings and the wall thickness of glass sheets complicate the numerical investigations. The modeling strategy is presented, and the limitations of CFD tools are given. The experimental and numerical results show similar trends as known for perforated metal structures. The extraction efficiency of the packing prototype could also be reproduced with the column design tool LLECMOD.     

Towards the Development of Advanced Packing Design for Distillation in Rotating Packed Beds

The growing demand for flexible and compact separation technologies has promoted the application of high‐gravity technology, like rotating packed beds (RPBs). Mass transfer characterization and packing design play an important role in the development of this technology. This article provides a systematic approach towards the evaluation of packing and the development of advanced packing design for distillation in RPBs. For the latter, an additive manufacturing approach is used to develop a new Zickzack packing for RPBs. The new packing provides better mass transfer at reduced pressure drop compared to available conventional packings, while being competitive in terms of mass transfer with the industrially applied rotating zigzag bed at significantly reduced pressure drop.     

Effect of Structured Packing Characteristics on Styrene Monomer/Ethylbenzene Distillation Process

The application of various types of structured packings to separate styrene monomer/ethyl benzene in packed columns is presented. The investigation was conducted over a wide range of operating conditions such as packing type, pressure, and reflux ratio. Several structured packings were used for separation of styrene monomer/ethyl benzene and the optimum conditions were determined for each of them. The proper condition of separation process and appropriate parameters for achieving better efficiency was discussed. The calculated results were compared with those obtained in industrial scale. It was shown that Mellapak‐Plus 252Y and 452Y packings can provide the maximum capacity with an acceptable level of efficiency over a wide range of operating conditions.     

Investigation of flow parameters and efficiency of mixture separation on a structured packing

Results of experimental study of the effect of initial maldistribution of structured packing irrigation on efficiency of binary mixture separation are presented in this article. The studies were carried out in the experimental distillation column with the diameter of 0.9 m using the R114 and R21 freon mixture. Experiments were performed on the structured Mellapak 350.Y packing of stainless steel 316L, containing 19 layers with the total height of 4.016 m at the ratio of mole liquid and vapor flow rates L/V = 1 and 1.7, respectively, and the pressure in the upper part of the column p_top = 3 bars. Nonuniformity at the packing inlet was generated via the blocking of some holes in the liquid distributor. Here, we present some results on efficiency of mixture separation, pressure drop on the packing, distribution of local liquid flow rate under the packing over the cross‐section and on the column wall within the range of vapor loading factor (0.69 < F_v < 1.61 Pa^0.5), as well as experimental data on distribution of local concentration of the low‐boiling component over the cross‐section and along the height of the structured packing. It is found out that significant maldistribution of mixture concentration and liquid flow rate over the cross‐section slightly changes along the height in the lower part of the column at a change in the degree of packing irrigation nonuniformity at the inlet. It is shown that efficiency of mixture separation depends considerably on the value of parameter L/V, vapor flow factor F_v, and size of the zone underirrigated by liquid at the inlet. In the studied range of liquid and vapor flow rates, the relative pressure drop on the packing does not depend on the ratio of liquid and vapor flow rates L/V and degree of irrigation maldistribution. © 2013 American Institute of Chemical Engineers AIChE J 60: 690–705, 2014     

复合板网填料性能研究

对一种新型的金属复合板网填料进行了研究,它是由三层板网贴合为复合基材后加工成波纹填料。在500冷模实验塔内对250Y型填料的测试结果表明复合板网填料具有显著的性能优势。三层复合板网填料的压降比常用的金属板波纹填料低60%以上,通量大20%～40%。氧解吸实验结果表明三层复合板网填料的分离效率明显高于单层板网填料,尤其在液气比低的工况下,效率可以倍增,和广泛应用的金属Mellapac填料相比,复合板网填料的分离效率能高30%左右。     

Cover Chem. Eng. Technol. 4/2013

CFD‐assisted Packing Optimization The glass packing QVF DURAPACK® was developed to use the advantages of structured mass transfer packings, especially when handling corrosive media. To match up with the latest developments for sheet metal packings, further optimization for liquid‐liquid separation processes was performed for the QVF DURAPACK®. The complex geometry of structured packings and the wall thickness of glass sheets complicate the numerical investigations. The modeling strategy is presented, and the limitations of CFD tools are given. The experimental and numerical results show similar trends as known for perforated metal structures. The extraction efficiency of the packing prototype could also be reproduced with the column design tool LLECMOD. DOI: 10.1002/ceat.201200531 CFD‐assisted Characterization and Optimization of the Structured Mass Transfer Packing QVF DURAPACK® C. Dreiser, G. Gneist, H.‐J. Bart* Chem. Eng. Technol. 2013 , 36 (4), 545–551     

Computational Fluid Dynamics Characterization of High-Capacity Structured Packing

The novel wire gauze structured packing, PACK-860, was characterized by means of numerical methods. The main features of PACK-860 such as height equivalent to a theoretical plate (HETP) and dry/wet pressure drop were evaluated. The flow structure in this packing was described by numerical simulation. To estimate the amount of HETP and dry/wet pressure drop, three-dimensional computational fluid dynamics (3D CFD) modeling with the Eulerian-Eulerian multiphase approach was applied. The average relative errors between the results obtained from CFD simulation and experimental findings for mass transfer efficiency and wet and dry pressure drop were assessed. Numerical observations were found to agree well with the empirical results, proving the reliability of CFD simulations for modeling separation processes.