新型旋转填料床强化气膜控制传质过程

转子结构为相互嵌套填料环的新型旋转填料床是基于强化气膜控制传质过程的新型高效传质设备,可适用于受气膜控制的吸收、精馏和低浓度工业气体的净化等过程。分别以化学吸收体系CO2-NaOH和物理吸收体系NH3-H2O测定了不同气量、液气比和超重力因子条件下的有效比表面积a和气相体积传质系数kya,并由此得到气相传质系数ky,对其传质性能进行研究。实验结果表明：a、kya和ky均随着气量、液气比和超重力因子的增大而增大。通过对比可知,新型旋转填料床的气相体积传质系数在相近操作条件下是文献逆流旋转填料床的2倍。并对实验数据进行了回归,拟合出了a、kya和ky分别与气相雷诺数ReG、液相韦伯数WeL和伽利略数Ga之间的关联式。     

超临界条件下甲醇合成的气液传质系数测定

以液体石蜡为惰性液相载体,正己烷为超临界介质,合成气制甲醇为研究体系,测定了超临界条件下三相浆态床中甲醇合成的气液传质系数。在反应温度238℃、合成气分压3.7 MPa、气体空速2744 h^-1条件下,通过不断增加催化剂浓度提高气液传质阻力和反应阻力的相对大小,采用外推法获得完全处于气液传质控制下的气液传质系数。计算结果表明：催化剂浓度对CO的气液传质系数的影响较大,而对CO₂的气液传质系数的影响较小;液相条件下CO、CO₂的气液传质系数分别是0.161、0.03 s^-1,而超临界三相甲醇合成中CO、CO₂的气液传质系数分别是0.199、0.042 s^-1,说明三相浆态床甲醇合成中引入超临界流体利于气液传质,验证了超临界介质中三相甲醇合成的优越性。     

不同填料错流旋转填料床气液传质特性研究

为了探索不同填料错流旋转填料床的传质性能,以Na2CO3水溶液吸收空气中硫化氢为实验体系,对装有不锈钢丝网、塑料波纹孔板和θ环填料的错流旋转填料床的气液传质性能进行研究。实验确定的适宜操作条件为:超重力因子7.8,气体流量2 m3/h,液气比20 L/m3,碳酸钠质量浓度12 g/L;在此条件下,3种填料的脱硫率均可达到90%以上。在相同操作条件下,不锈钢丝网填料的脱硫率及气相总体积传质系数大于塑料孔板填料大于θ环填料;错流旋转填料床中,规整填料的气液传质效果优于乱堆填料。文中的研究结果为错流旋转填料床填料的选取及在脱硫方面的应用提供了依据。     

多孔波纹板错流旋转床的传质性能

以CO2-NaOH为介质,研究了两种板间距填料结构的传质性能。结果表明：多孔波纹板错流旋转床的体积传质系数在相近的操作条件下分别比文献丝网错流旋转床高0.95～2.1倍、比逆流旋转床略低,比传统气液传质设备高1～2个数量级。应用MATLAB语言编制应用程序对实验数据的回归分析得出了体积传质系数的关联式。     

超重力旋转填充床氧解吸过程的数值模拟

基于旋转填充床流体流动的可视化结果,建立了超重力旋转填充床气液传质过程的数学模型,模拟氮气解吸水中溶解氧的传质过程。模拟结果表明,缩短液相停留时间、提高液相扩散系数都能增大液相传质分系数k_L;总体积传质系数K_La随超重力因子的增加而增大、随温度的上升而增大、随气相流率的增加略有下降、随液相流率的增加明显增大;空腔区传质贡献率随空腔区的增大而增大,随超重力因子的增大而减小;且短暂的停留时间是超重力旋转填充床对传质过程强化的本质原因。模型较好地符合文献的实验数据,误差在±16%以内。     

超重力旋转填充床氧解吸过程的数值模拟

基于旋转填充床流体流动的可视化结果,建立了超重力旋转填充床气液传质过程的数学模型,模拟氮气解吸水中溶解氧的传质过程。模拟结果表明,缩短液相停留时间、提高液相扩散系数都能增大液相传质分系数kL;总体积传质系数KLa随超重力因子的增加而增大、随温度的上升而增大、随气相流率的增加略有下降、随液相流率的增加明显增大;空腔区传质贡献率随空腔区的增大而增大,随超重力因子的增大而减小;且短暂的停留时间是超重力旋转填充床对传质过程强化的本质原因。模型较好地符合文献的实验数据,误差在±16%以内。     

化学吸收法测定多级离心雾化旋转填料床有效相界面积及体积传质系数

对多级离心雾化旋转填料床的有效相界表面积及体积传质系数,用化学吸收法做了实验测量。实验结果表明：多级离心雾化旋转填料床不仅具有超低气阻,而且可产生良好的喷雾扩展相界面积的作用,体积传质系数比传统填料塔提高一个数量级,接近气液逆流型旋转填料床。多级离心雾化旋转填料床开拓了新的气液传热传质途径。     

超重力旋转床中水脱氧过程的模型化研究

超重力旋转床是一种高效的强化传质和混合的新型设备。今提出了超重力旋转床中的水脱氧过程的传质模型,分别采用欧拉方法和拉格朗日方法对超重力旋转床中的气相和液滴的运动行为进行了数值模拟;在此基础上计算了液滴的传质系数,计算结果和实验结果符合较好,平均误差为7．9％。当超重力旋转床中液体存在的主体形式更接近于液滴时,模型计算结果误差减小。进一步讨论分析了液体和气体流量、转速以及填料内径的变化对于超重力旋转床体积传质系数的影响,分析表明旋转填料对液体剧烈地剪切破碎分散作用是强化传质过程的主要原因。     

超重力场内气液传质强化研究进展

气液传质过程广泛存在于化学工业当中。气液传质强化技术的研究, 对缩短工艺流程、缩小设备尺寸、降低投资和运行成本等具有重要的意义。以旋转床为核心装备的超重力技术, 是气液传质过程强化的有效技术之一。经过30多年的发展, 超重力过程强化技术在基础和应用研究方面都取得了长足的进展, 特别是在受混合和传递限制的过程中得到广泛应用。本文从旋转床转子结构出发, 综述了整体旋转式、双动盘式、动静结合式等转子结构的超重力旋转床气液传质强化的研究进展和理论成果, 并展望了超重力旋转床气液强化传质的发展方向。     

超重力旋转床中的传质研究

超重力旋转床是８０年代出现的新型传质设备，该设备利用远大于重力的离心力，极大地强化了气液或液固间的接触，增强了传质效果。在相同的传质条件下，与重力场中的设备相比，该设备的体积小、操作强度大、体积传质系数ＫＬα大，可广泛适用于各种气液传质，也适用于液固传质。理论研究由传统的重力作用下的传质发展到超重力场作用下的传质。本文对近年来关于超重力旋转床中的薄膜厚度、比表面积、传质系数等的研究结果作了综述、分     

多级雾化旋转填料床的传质性能

以两级雾化超重力旋转床为例,用化学吸收法考察了超重力因子β、液体流量、气体流量等对体积传质系数kyα的影响。结果表明:多级雾化超重力旋转床的体积传质系数随气液流量的增加而增加,在β较小时,实验曲线的斜率较大,kyα随β的增加急剧增加;但是当β超过100后,曲线的斜率减小,kyα随β的增加缓慢增大。     

新型旋转填料床的气相传质特性

以CO2-NaOH体系化学吸收测定不同超重力因子、液量和气液比(体积流量比)条件下的有效传质比表面积a,在相同操作条件下,以氨-空气-水体系进行空气吹脱含氨富液测定不同超重力因子、液量和气液比条件下的气相体积传质系数kya,从而得到气相传质系数ky,对其气相传质特性进行了研究. 结果表明,a随超重力因子、液量和气液比增大而增大,kya和ky均随超重力因子和气液比增大而增大,随液量增大而减小. 通过对比可知,在相近操作条件下新型旋转填料床的气相体积传质系数比文献折流旋转填料床的提高36%. 对实验数据进行回归,拟合出a, kya和ky分别与气相雷诺数ReG、液相韦伯数WeL和伽利略数Ga之间的关联式.     

旋转填充床内高黏介质脱挥过程的传质模型(英文)

A mass transfer model for devolatilization process of highly viscous media in rotating packed bed(RPB) was developed based on penetration theory and mass conservation.Before establishing the model,some mass transfer experiments of thin film were conducted in a designed diffusion cell including vacuum and feeding system. In this study,acetone was used as the volatile organic compound(VOC) and syrup as the highly viscous media.The thickness of thin film was changed by using different liquid distributor.It was found that bubbling played an important role in the devolatilization.The correlation of diffusion coefficient of acetone in highly viscous dilute solution was proposed.The relative error between predicted and experimental data was within the range of ± 30% for diffusion coefficient of acetone in syrup.A comparison of experimental data of RPB with model indicated that the relative error was within ± 30% for efficiency of acetone removal.     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid-solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid-solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid-solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ±12%. The liquid-solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04-0.14 1^-1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

Modeling and experimental studies on absorption of CO2 by Benfield solution in rotating packed bed

This work presents the modeling and experimental investigation on absorption of CO₂ by Benfield solution in rotating packed bed (RPB). A model was established to illustrate the mechanism of gas–liquid mass transfer with reactions in RPB at higher gravity level. Experiments were carried out at various rotating speeds, liquid flow rates, gas flow rates and temperatures in RPB, with Benfield solution as the absorbent. The validity of this model was demonstrated by the fact that most of the predicted y_o (mole fraction of CO₂ in outlet gas) agreed well with the experimental data with a deviation within 10%. The presented profile of K_Ga (gas-phase volumetric mass transfer coefficient) along the radial direction of the packing could reasonably explain the end effect in RPB. As a result, this model is reliable in describing the removal of CO₂ by Benfield solution in RPB at higher gravity level.     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ± 12%. The liquid–solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04–0.14 1⁻¹, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

并流旋转床压降与传质特性的研究

利用水-空气系统对并流旋转床的气相压降进行了研究,并与逆流旋转床气相压降进行了对比。研究结果表明：并流较逆流旋转床的气相压降低;并流旋转床的气相压降随气体流量的增大而增大,随液体流量的增大而减小,随转速的增大明显降低;而逆流旋转床的气相压降随转速的增大明显升高。利用水吸收SO2的实验对并流旋转床的传质特性进行了研究。研究结果表明：并流旋转床填料层内各点的体积传质系数随着气体流量、液体流量和转速的增大而增大;填料层半径由70mm增大至90mm时,并流旋转床的体积传质系数迅速增大,而后并流旋转床的体积传质系数随半径的增大而减小。对并流和逆流旋转床填料层内体积传质系数进行了对比。结果表明：填料层半径由70mm增大至130mm时,并流旋转床的体积传质系数较逆流时大;当半径大于130mm后,逆流旋转床的体积传质系数大于并流旋转床的体积传质系数,且随半径增大而增大。根据研究结果,提出了降低系统压降的设想,即并流与逆流旋转床串联操作。