A Study on Modern High Effective Random Packings for Ethanol‐Water Rectification

Raschig Super‐Ring is a modern and high‐efficient packing used for intensification of absorption and distillation processes. The aim of this work is to characterize the efficiency of this packing applied to rectification of an important industrial system, ethanol‐water, and to compare its efficiency to that of some random packings of the third generation as well as to the structured packing, HOLPACK, which is used in the ethanol production industry. The experiments were carried out in a column installation, 0.213 m in diameter with a packing height of 2.8 m. The column is heated by a number of electrical heaters (total power 45 kW), which can be switched gradually. Operation at total and partial reflux is possible. Eight types of random packings were studied: five types of Raschig Super‐Ring, four metallic (with characteristic dimensions 0.5, 0.6, 0.7, and 1”) and one of plastic material 0.6”; two types of packing IMTP and one plastic Ralu Flow. Some experiments were conducted at total reflux operation at vapor velocity, 0.253–0.936 m/s, and liquid superficial velocity, 4.44 · 10^–4–1.63 · 10^–3 m³/(m²s). Experiments at partial reflux were carried out at constant liquid superficial velocity and changeable vapor velocity as well as at constant vapor velocity and changeable liquid velocity. The results are presented as height of transfer unit, HTU, and height equivalent to a theoretical plate, HETP, as a function of the velocity of phases.     

Enzyme mass transfer coefficient in aqueous two phase system using a packed extraction column

Fractional dispersed phase hold-up and dispersed side mass transfer coefficients for amyloglucosidase were measured in a 56 mm i.d. packed extraction column using a sodium sulphate-polyethylene glycol 4000 system. Raschig rings (3 to 13.3 mm), Berl saddles (12 mm), Pall rings (12.6 mm), glass spheres (5.2 mm) and structured wire gauze were used as packings. The effect of packing size was investigated in the case of ceramic Raschig rings. The effect of phase composition of the aqueous phase system also was studied. Correlations have been developed for fractional dispersed phase hold-up and volumetric mass transfer coefficient with packing voidage, dry surface area of packings, superficial dispersed phase velocity and the liquid phase physical properties.     

气流在板波填料内的径向混合——(Ⅰ)试验与关联

本文在φ200和φ287mm两种塔内,对4.5型和6.3型板波填料进行了气流径向混合试验,试验采用CO_2作为示踪剂.试验结果表明,板波填料具有良好的径向混合性能.4.5型板波填料的Pe_r仅为1.5左右,而φ15mm拉西环的Pe_r约为3.5.影响气流在板波填料中径向混合的因素有:填料的盘高、盘径、波纹倾角以及气速等.在低Re下,板波填料的Pe_r较低,且随Re的增大而增加,当Re>800以后.Pe_r趋于定值.本文提出了Pe_r与诸参数间的经验关联式.     

LDA measurements of liquid velocities in a refractive index matched packed bubble column

LDA has been used to measure liquid velocities in a small-scale bubble column, internal diameter of 50 mm, packed with glass Raschig rings, 10 and 15 mm. A mixture of benzyl-alcohol and ethyl alcohol was index matched against the packing material. A method to separate the signals from liquid and bubbles was developed. It was found that the axial time-averaged liquid velocity was lower than that obtained in empty bubble columns, and that both the time-averaged liquid velocity and the RMS value of the liquid increased for the larger packing size.     

开孔与层数对丝网波纹填料流体力学性能的影响

测定了单层无孔、双层无孔、单层开孔和双层开孔4种不同结构的金属丝网波纹填料的流体力学性能,以研究表面开孔和丝网层数对丝网波纹填料流体力学性能的影响。在直径100 mm的有机玻璃塔中使用空气-水体系对4种不同结构的金属丝网波纹填料进行了干填料压降、湿填料压降、泛点气速、持液量等流体力学性能测试。试验结果表明,4种丝网填料中双层开孔填料的干填料压降与湿填料压降低、泛点气速大、持液量适中,较其余3种填料流体力学性能更优秀。     

无油润滑填料密封的改进

无油润滑密封填料塞入填料函后受到压盖的压力,但是靠近压盖远端的填料受到的压力比填料压盖近端小,导致填料轴向和径向受力小,变形量小,引起泄漏.如果把压盖螺栓过力拧紧,会导致填料变形过大,轴受到的力过大,产生大量的摩擦热并加剧轴的磨损.本文从材料成分配比和填料环结构两方面入手,改进填料密封.经过实验表面,这种材料和结构大大提高了密封效果.     

无油润滑填料密封的研究

无油润滑密封填料塞入填料函后受到压盖的压力,但是靠近压盖远端的填料受到的压力比填料压盖近端小得多,导致填料轴向和径向受力小,变形量小,引起泄漏。如果把压盖螺栓过力拧紧,会导致填料变形过大,轴受到的力过大,产生大量的摩擦热并加剧轴的磨损。从材料成分配比和填料环结构两方面入手,改进填料密封。经过实验表面,这种材料和结构大大提高了密封效果。     

分层填料对旋转填料床气相流场影响的数值模拟

通过设计简化的分层填料旋转床(SP-RPB)模型,采用计算流体力学方法(CFD)对比同尺寸旋转填料床(RPB)的稳态气相流场。分析转速和进料速度对气相压力、相对速度及湍动能分布的影响,同时还考察了单位丝网圈上的压降情况。结果表明,在气体进入各级填料位置的相对速度出现峰值,湍动能分布与之相同,各峰的出现位置仅由填料位置决定,两者共同表明SP-RPB具有多个端效应区域。转速增加对相对速度峰值大小有更明显的提升,较大的进料速度使填料内气体的速度波动更大,也使湍动能的峰值有所增加。由于SP-RPB内填料厚度较RPB变薄,从整个设备范围上看,SP-RPB表现出更低的压降。进气速度提高和转速降低使SP-RPB两层填料间的高压范围变窄,但SP-RPB的单位丝网圈数压降更大。     

Numerical prediction of residual stresses and birefringence in injection/compression molded center‐gated disk. Part II: Effects of processing conditions

The accompanying paper, Part I, has presented the physical modeling and basic numerical analysis results of the entire injection molding process, in particular with regard to both flow‐induced and thermally‐induced residual stress and birefringence in an injection molded center‐gated disk. The present paper, Part II, investigates the effects of various processing conditions of injection/compression molding process on the residual stress and birefringence. The birefringence is significantly affected by injection melt temperature, packing pressure and packing time. However, the thermally‐induced birefringence in the core region is insignificantly affected by most of the processing conditions. On the other hand, packing pressure, packing time and mold wall temperature affect the thermally‐induced residual stress rather significantly in the shell layer, but insignificantly in the core region. The residual stress in the shell layer is usually compressive, but could be tensile if the packing time is long, packing pressure is large, and the mold temperature is low. The lateral constraint type turns out to play an important role in determining the residual stress in the shell layer. Injection/compression molding has been found to reduce flow‐induced birefringence in comparison with the conventional injection molding process. In particular, mold closing velocity and initial opening thickness for the compression stage of injection/compression molding have significant effects on the flow‐induced birefringence, but not on the thermal residual stress and the thermally‐induced birefringence.     

散装填料塔载点气速的计算与应用

指导出了散装填料层的载点关联式,通过对6种填料的填料层载点气速的计算表明,本文关联式的计算值与实验值吻合较好,计算准确性优于文献公式。简述载点气速的应用。     

COMPARISON OF HYDRODYNAMIC AND MASS TRANSFER PERFORMANCE OF SMR,RASCHIG RING AND PULSED PERFORATED PLATE COLUMN

ABSTRACT

Cyanex 923 has been proposed as an extractant for the removal of sulphuric acid from copper tank house bleed streams. This process requires many stages and so is ideal for column operation. This paper presents a comparison between three types of column for this service. The new SMR packing marketed by Glitsch is the first packing developed specifically for liquid-liquid extraction service and is compared with a column packed with Raschig rings and a pulsed perforated plate column.     

填料层阻力的实验研究

对鲍尔环、阶梯环和多面空心球三种填料的阻力进行了测试,得出了填料层的阻力系数。结果表明：在相同的条件下,鲍尔环阻力最大、阶梯环阻力最小、多面空心球阻力居中。干填料层的阻力系数随空塔气速的增大而减少,湿填料层的阻力系数随空塔气速的增大而增大。利用阻力系数法计算填料层阻力具有简单、准确的优点。     

XD-1新型锥度螺旋填料的流体力学特性与机理

XD-1型锥度螺旋填料独特的锥度螺旋结构能使气液二相由逆流接触转变为错流接触,使之与常规填料有完全不同的流体力学特性。在80 mm的冷模实验塔内,用空气-水物系测定了填料的流体力学特性,还与θ环、拉西环和丝网波纹填料进行了比较。实验结果表明,在相同喷淋密度下,锥度螺旋、拉西环、θ环和波纹丝网4种填料的空隙率之比为:0.823∶0.781∶0.947∶0.855时,单位填料层压降之比为:0.58∶1.35∶1.08∶0.65,泛点气速之比为:0.725∶0.280∶0.658∶0.703。     

Determination of mass transfer coefficients for packing materials used in biofilters and biotrickling filters for air pollution control—2: Development of mass transfer coefficients correlations

Correlations that allow determination of gas film mass transfer coefficients (k_Ga_t, k_Ga_w) and liquid film mass transfer coefficients (k_La_w) for packing materials used in biofilters and biotrickling filters for air pollution control are presented. Lava rock, polyurethane foam cubes (PUF), Pall rings, porous ceramic beads, porous ceramic Raschig rings, and various compost-woodchips mixtures were used as packing materials. The functionality of gas and liquid velocity on mass transfer coefficients (k_Ga_t,k_Ga_w,k_La_w) obtained experimentally (see Part 1 of this paper) was correlated using modified Onda-type equations. The correlation equations helped to better understand the sensitivity of gas and liquid velocities on mass transfer, and the effects of packing wetting. Each packing had a different functionality with gas and liquid velocity and different wetting property, hence different correlation equations were needed for the different packing materials. Most of the fitted data fell within ±20% of the experimental values.     

Crystallographic study of two monoazo disperse dyes with a D–π–A system

Two azo disperse dyes, 2,6‐dichoro‐4‐nitro‐4′,4′‐N‐cyanoethyl‐N‐benzyl‐azobenzene ( D1 ) and 3‐(3‐methyl‐4‐N‐ethyl‐N‐benzyl‐phenyldiazenyl)‐5‐nitro‐2,1‐benzisothiazole ( D2 ), were synthesised and characterised. The crystal morphologies and single crystal structures were measured. The various packing and supramolecular interactions were described. D1 formed stellate crystals. The two benzene rings bilateral to the azo unit were not coplanar. Their dihedral angle was 75.72°. They were linked by the azo unit and were twisted. The coupling‐component N‐substituted benzyl and benzene rings were not coplanar. The chemical structure was not the typical azo structure. A dimeric packing mode was formed between adjacent molecules in a head‐to‐head and tail‐to‐tail manner. One molecule was inserted between two dimeric molecules in a head‐to‐tail manner. D2 formed globe crystals. The isothiazole and benzene rings of the azo unit were coplanar, with the typical π–π conjugated structure. The benzene rings of the azo unit and the coupling‐component N‐substituted benzyl were vertical. Their torsion angle was 179.9°.     

基于颗粒堆积理论的管壁水合物沉积层力学特性研究

管壁水合物沉积层的稳定性与管壁水合物沉积层的力学特性密切相关,研究管壁水合物沉积层的力学特性对深水流动安全保障具有重要意义。为研究管壁水合物沉积层的力学特性,假设沉积层内所有水合物均为大小相同的球形颗粒,且沉积层是由多层水合物颗粒相互堆积而成。根据水合物颗粒堆积方式的不同,将管壁水合物沉积层分为简单立方堆积型、六方堆积型、复六方堆积型、四面体堆积型、角锥堆积型和随意堆积型6类。不同类型的水合物沉积层对应有不同的空隙率和层间受力特性,以此为基础,分别计算分析了各类水合物沉积层的压缩波速、剪切波速、泊松比、弹性模量、抗拉强度,并依据摩尔--库仑强度准则给出了各类管壁水合物沉积层的抗剪强度。同时,计算分析了退火作用对管壁水合物沉积层抗拉强度和抗剪强度的影响。本文研究成果可为油气管道水合物防治技术的发展提供理论支持。     

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.     

利用同步辐射X射线小角散射研究超低水灰比水化水泥早期微结构

利用同步辐射X射线小角散射技术表征超低水灰比水泥水化早期产物分形结构,研究水化水泥早龄期微结构及演变。水泥水化早期水化产物双分形结构表明：水泥水化硅酸钙纳米凝胶颗粒随机堆积,内外层水化产物中纳米凝胶粒子结构分别具备不同的自相似性;内层水化产物中高密度凝胶堆积紧密,早龄期时随水化时间增加,堆积密度降低。外层水化产物中低密度凝胶堆积较为松弛,早龄期时随水化时间增加,堆积密度也在降低;水化诱导期生成结构最为致密的一层凝胶产物,诱导期后,凝胶产物层堆积密度随水化龄期的增加而减小,水化反应平缓后,凝胶堆积密度的演变也趋于平缓。     

Performance characteristics of a packing with boundary layer turbulizers. IV. Gas-film controlled masstransfer

The gas-film controlled mass-transfer rate in a honeycomb packing, with stamped groove turbulizers (Turbo-Pack) which affect the region of the boundary layer, has been studied. An equation for determining the mass-transfer coefficient as a function of gas velocity and the geometrical dimensions of the packing has been derived. It is found that the effect of the height of packing blocks is far less than that forecast by Zhavoronkov's equation which was derived for packings with a much higher wall thickness. Comparison of experimental data relevant to the novel design with reference packings cited in the literature shows that as far as its low values of pressure drop per mass transfer unit are concerned the Turbo-Pack packing is superior to all other known packings.     

Hydrodynamics and mass transfer in a pulsed packed column

The hydrodynamics and mass transfer characteristics of a pulsed packed column (PPC) filled with a stainless steel super mini ring (SMR), ceramic and stainless steel Raschig rings have been studied using a 30% tributyl phosphate‐kerosene (dispersed phase)/acetic acid/water (continuous phase) system. Experiments were performed in a 100 mm internal diameter column with 1.0 m height of packing. The mass transfer and axial mixing parameters were estimated simultaneously from the measured concentration profiles of two‐phase based on the backflow model. It was found that pulsation has great influence on hydrodynamics and mass transfer characteristics of PPC with the SMR. H_oxp and H_ox decrease significantly with pulsation, whereas flooding velocity decreases only slightly. Comparison among the three types of packing showed that the SMR has superior characteristics both in terms of capacity and mass transfer efficiency. The influence of mass transfer on characteristics of PPC was also studied. New empirical equations of characteristic velocity, H_oxand H_oxd were proposed and good agreement between calculated and experimental data was obtained.