对二甲苯鼓泡塔氧化过程的实验研究

以醋酸为溶剂,醋酸钴、醋酸锰为催化剂,溴化物为促进剂,在实验室鼓泡塔式反应器中,进行了对二甲苯(PX)氧化生成对苯二甲酸(TA)的工艺过程的研究,考察了氧化反应温度、压力、催化剂浓度、溶剂比等条件对粗对苯二甲酸(TA)产品中对甲基苯甲酸(p-TA)和对羧基苯甲醛(4-CBA)两种主要杂质含量以及产品粒度的影响。为工业装置对苯二甲酸产品粒度的改善和杂质含量的降低提供基础实验数据。     

鼓泡塔内热质同时传递过程研究

在鼓泡塔内的热模实验表明,塔内存在一个适宜的液汽比。比较鼓泡塔和填料塔得出,完成相近的传热和传质负荷,鼓泡塔传热传质效率不及填料塔、鼓泡塔的蒸汽利用程度比填料塔高;鼓泡塔的操作弹性、设备堵塞等问题优于填料塔。故鼓泡塔亦是较理想的热水塔塔型,可用于水煤浆气化系统。     

对二甲苯富氧氧化的研究及工业化试验

研究了以Co-Mn-Br为催化剂,对二甲苯(PX)液相氧化下不同氧浓度(质量分数21％~31％)和不同空速对对苯二甲酸(TA)产率、中间产物含量、PX消耗速率和尾气中二氧化碳含量等的影响。结果表明:提高进气中氧浓度,尾气中氧浓度相应提高,有利于加快PX的氧化和TA的生成速率,且未加剧醋酸深度氧化生成二氧化碳。在PX处理量一定时,提高进气氧浓度可大大降低气体空速。工业化富氧(氧气质量分数23％)条件下的氧化反应安全可行,不影响产品质量。     

不同类型鼓泡塔气液并流时液相轴向扩散系数

在相同尺寸的鼓泡塔、筛板鼓泡塔、振动筛板鼓泡塔中采用脉冲示踪法对空气-水体系进行轴向返混实验研究,考察了水和空气流速对鼓泡塔、鼓泡筛板塔液相轴向扩散系数(EZ)和水、气体流率、筛板振动强度对振动筛板鼓泡塔液相轴向扩散系数的影响.结果表明,鼓泡塔EZ与uL0.696～1.158成正比(uL为液速);筛板鼓泡塔EZ与uL和气速(uG)关系式为EZ=0.798uG0.77uL1.252;振动筛板鼓泡塔的EZ与uL0.8354～1.2740成正比.     

亚硫酸铵微界面强化氧化特性研究

以亚硫酸铵水溶液的空气氧化为研究对象，考察了微界面强化对该体系传质与氧化过程的影响。在同一实验平台和操作工况下，对微界面强化与传统鼓泡塔氧化过程的传质和反应性能进行了实验研究。利用高速摄像与压差测量技术，分别对反应过程的空气气泡分布与气含率变化进行了测定。结果表明，相较于传统鼓泡塔空气氧化反应器，微界面强化氧化反应器以微界面体系取代了传统毫-厘米级宏界面，在不同盐离子浓度与氧化气量工况下均表现出了良好的强化效能。在微界面体系强化下，亚硫酸铵氧化过程气含率大幅提升，相界面积增加十余倍，反应速率平均提升56.8%，实验结论为微界面强化反应器的多相反应体系工业应用提供了一定的数据支撑。     

管壳式鼓泡降膜塔的流体力学研究

本文提出了管壳式鼓泡阵膜塔的结构构思与操作工况.该塔的列管具有两种流体分布器,上端口的液体分配器与降膜塔相似,下端口的气体分布器与鼓泡塔相似,以实现列管内上半段降膜、下半段鼓泡的鼓泡降膜联合操作.文中阐述了在φ16—36mm单管和多管(塔径φ200mm)中水-空气系统的流体力学实验结果.实验表明,该塔具有良好的操作性能:气液负荷大,操作弹性大,两相流状态稳定,鼓泡层返混较小,兼具鼓泡塔和降膜塔的特点.实验并为这种新型反应器提供了必要的设计数据.     

振动筛板鼓泡塔中NaCO_3-CO_2-H_2O体系的反应速率

研究了不同CO_2流量、筛板振幅、筛板振动频率下,反应时间对振动筛板鼓泡塔中NaCO_3-CO_2-H_2O体系的NaHCO_3浓度和NaHCO_3生成速率的影响,测定了振动筛板鼓泡塔、鼓泡塔和筛板鼓泡塔在相同条件下的反应速率.结果表明,在振动筛板鼓泡塔中反应20~25min时,CO_2高流量与低流量下的NaHCO_3浓度比为1.39.反应进行5min时,NaHCO_3生成速率在筛板振幅为0.5cm时是1.5cm时的1.76倍,振动频率为120min~(-1)时是60min~(-1)时的1.46倍.振动筛板鼓泡塔比筛板鼓泡塔节省反应时间10%,比鼓泡塔省时26%.     

多级鼓泡塔内液体速度分布的实验研究

液体循环流动是多级鼓泡塔重要流体力学特征之一,文中在内径为282 mm,高2000 mm的鼓泡塔内,采用不同类型的筛板将普通鼓泡塔分割成双级气液鼓泡塔.采用Pavlov管测液速的方法考察了不同筛板、不同表观气速下该鼓泡塔中上下二侧的液体速度分布.根据实验结果得出了液体速度在塔中心处最大,且与表观气速有关,随着表观气速的...     

列管束内构件对鼓泡塔流动发展的影响

在Φ500 mm×4000 mm的大型冷模实验装置内考察了列管束内构件对鼓泡塔流动发展的影响。以空气-水为工作体系,分别采用电导探针和Pavlov管测量了有、无列管的鼓泡塔内不同轴向高度的气含率和液体流速径向分布。实验表明,在安装密集列管束的鼓泡塔内也存在一个充分发展段。与空塔不同的是,列管束的存在使分布器影响区显著延长,从空塔的约两倍塔径高度增至约四倍塔径高度,在冷模装置中占据塔体积的50%以上。在实验条件下,鼓泡塔高径比或液位高度对分布器影响区大小没有明显影响。     

鼓泡塔反应器中亚硝酸甲酯合成工艺研究

在鼓泡塔反应器中采用半连续操作,对亚硝酸甲酯(MN)再生反应进行了研究,考察了反应温度、甲醇溶液进科浓度、NO/O2比和表观气速等工艺条件对MN收率等的影响.实验认为,在填料湍流鼓泡塔反应器内NO/O2比和表观气速是影响MN收率的主要因素,确定了在常压条件下适宜的操作参数:反应温度为293～308 K,甲醇溶液浓度为4...     

A structured catalytic bubble column reactor: hydrodynamics and mixing studies

This paper reports the results of a comprehensive experimental study of the hydrodynamics and mixing in two bubble column reactors of 0.1 and 0.24 m in diameter with KATAPAK-S^® as packing material. Total gas hold up and axial dispersion coefficients were measured in the structured bubble columns and the values were compared with experimental results obtained in the same work with empty bubble columns. The results reveal that the gas hold up in structured bubble columns is practically the same as in empty bubble columns when compared at the same superficial gas velocity based on open area available for gas–liquid dispersion. The presence of the structured elements in the bubble column reactor reduces the liquid phase backmixing by one order of magnitude.     

Scale effects in fluidized multiphase reactors

It is shown that the two-phase model for bubbling gas—solid fluidized beds can be extended to bubble column slurry reactors operating in the heterogeneous flow regime by proper definition of the ‘dilute’ and ‘dense’ phases. The ‘dilute’ phase in a bubble column slurry reactor is to be identified with the fast-rising ‘large’ bubbles. The ‘dense’ phase consists of the slurry phase in which ‘small’ bubbles are finely dispersed. With the aid of extensive experimental data obtained in columns of 0.1, 0.19 and 0.38 m diameter it is shown that the rise velocity of the ‘dilute’ phase for gas—solid fluid beds and slurry reactors show analogous scale dependencies and can be modelled in a similar manner. It is also demonstrated that fluidized multiphase reactors can be modelled in a common manner using Computational Fluid Dynamics (CFD) within the Eulerian framework. It is concluded that CFD is an invaluable tool for scaling up of fluidized multiphase reactors.     

Rückvermischung in Blasensäulen mit Einbauten

Back-mixing in Bubble Columns Fitted with Internals. Interals installed in bubble column reactors serve mainly for heat transfer and for influencing (suppressing) liquid circulation. Reinforcement of mixing is observed for experimentally for internals subjected to longitudinal flow, which is attributable in limitation of transverse exchange and the resulting increase of axial eddy dimensions. The experimental findings can be readily described by the axial dispersion model for uniform cross sections and equations are given for estimating the dispersion coefficients of the gaseous and liquid phases as a function of the central liquid circulation velocity. Internals subjected to transverse flow hinder the establishment of a large scale circulatory motion and therefore suppress mixing on the bubble column. Two calculation procedures of differing model depth are presented which permit determination of concentration and temperature profiles in bubble column reactor cascades. Moreover, equations are given for estimating reflux conditions on sieve plates and bundled tube heat exchangers in cross flow which are based on experimental investigations.     

Quality of mixing in a downflow bubble column based on information entropy theory

Quality of mixing in a modified downflow bubble column has been analyzed by using information entropy theory. Mass transfer efficiency based on quality of mixing has also been enunciated in this work. Empirical models have been developed for downflow system with the parameters which affect the quality of mixing and mass transfer efficiency. The developed correlation for quality of mixedness in the downflow bubble column was interpreted by the mass transfer phenomena. The present analysis on the quality of mixing in downward two-phase flow in bubble column may give insight into a further understanding and modeling of multiphase reactors in industrial applications.     

Effect of bubble deformation on stability and mixing in bubble columns

The paper deals with hydrodynamics in bubble columns. The objective of the paper is to study stability and mixing in a bubble column. The modeling of parameters such as stationary drag and added mass is addressed. In addition, the effect of bubble deformation in terms of eccentricity is highlighted. In a previous paper, the transition between homogeneous and heterogeneous regimes in bubble column without liquid flow has been shown to be driven by the deformation of the bubbles associated to drag and added mass. In the present paper, this work is generalized to bubble column with liquid flow and to the transition from bubble flow to slug flow in a vertical pipe. Numerical simulations of gas-liquid reactors are presented. The numerical simulations are validated in the case of gas plume after the Becker et al. data (Becker, S., Sokolichin, A., & Eigenberg, G. (1994) Gas-liquid flow in bubble columns and loop reactors: Part II. Comparison of detailed experiments and flow simulations. Chemical Engineering Science, 49 (24B), 5747-5762. The numerical simulations are finally applied to a bubble column. The simulations of residence time distribution coupled to transient hydrodynamics are shown to be very sensitive to the modeling of interfacial transfer of momentum from the bubbles to the liquid in terms of drag and added mass, including the effect of bubble deformation.     

Modeling the ultrasonic cavitation‐enhanced removal of nitrogen oxide in a bubble column reactor

A model study of the sonochemical removal of nitric oxide (NO) in a bubble column reactor is presented. The detailed model is developed to investigate the actual cavitation phenomena taking place during the absorption of NO. The expansion and subsequent collapse of cavitation bubble according to the theory of cavity collapse—initially developed by Lord Rayleigh and then improved on by coupling the energy balance equation of the bubble and the chemical reactions taking place inside the cavity to calculate the composition of different species formed during the collapse—are modeled. The model takes into consideration (1) cavitation bubble dynamics, (2) generation and transfer of oxidizing species from bubble collapse through reaction kinetics, (3) transfer of NO from gas to liquid, and (4) chemical reactions of oxidizing species with dissolved NO. The results of the simulations surprisingly indicate that the chemistry induced by ultrasonic cavitation cannot explain the absorption of NO beyond about 30% of the inlet concentration if the mass transfer is assumed to be the same as that in the bubble column without ultrasound. When experimental values of mass‐transfer coefficients, calculated in the studies by other researchers (which are in the range of about five times the physical mass‐transfer coefficient in a bubble column), are used, absorption up to 80% are calculated in the simulations consistent with experimental results obtained from the sonochemical bubble column reactor. The present model provides a framework on which more robust and rigorous models can be developed for the complex gas‐liquid sonochemical systems and reactors. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2397–2411, 2012     

鼓泡塔细胞反应器流体力学与传质特性

以超大规模细胞培养为目的,构建了与细胞培养体系十分接近的冷模实验体系,系统地研究了微载体(Cytodex I)、细胞保护剂(Pluronic F68)和消泡剂(Antifoam C)对鼓泡塔反应器中气、固、液三相流流体力学和氧传质特性的影响。在0.04~0.17 cm/s表观气速范围内采用50 μm孔径的烧结金属滤芯曝气时,在含有0.5和1.0 g/L的Pluronic F68的磷酸盐缓冲溶液冷模体系中,气含率与表观气速成线性增加关系,而气泡直径受表观气速影响较小;相同气速下的冷模体系与空气-水体系相比,气含率显著提高,气泡直径明显减小。在所研究的表观气速范围内微载体均可全悬浮,对气含率有一定增强,但微载体浓度为14%~20%时对气泡大小几乎无影响。消泡剂用量在1.60×10-4时,可以有效抑制泡沫的形成。添加剂对液膜传质系数kL有较大负面作用,抵消了小气泡带来的传质面积增加,总的体积传质系数kLa变化不大。Euler-Euler多相流计算流体力学模型与拟稳态实验数据吻合较好,可用于指导反应器放大设计。     

A scale-up strategy for low-temperature methanol synthesis in a circulating slurry bubble reactor

Slurry bubble column reactors are being increasingly utilized in the large-scale conversion of coal or natural gas to liquid hydrocarbons and alcohols. A new suite of tools for developing low-temperature methanol synthesis in circulating slurry bubble reactors is explored in this study. The scale-up strategy consisting of hydrodynamics in cold flow units, catalyst performance evaluation in an autoclave, and process investigation in a pilot-scaled circulating slurry bubble reactor is presented. This methodology should be helpful for designing and scaling-up the low-temperature methanol synthesis and other related processes in slurry bubble column reactors, which will enhance and speed them towards commercial application.     

SIGNIFICANCE OF THE CENTRAL PLUME VELOCITY FOR THE CORRELATION OF LIQUID PHASE MIXING IN BUBBLE COLUMNS

The knowledge of the flow patterns of each phase of bubble column reactors is of considerable importance for the rational design and scale-up. The hydrodynamic models for the liquid phase have been reviewed. The models have been based on some form of pressure balance or energy balance. These two approaches have been compared and recommendations have been made regarding the range of applicability of the individual models. A comparison between the predicted and the experimental liquid velocities has been presented whenever possible. The range of variables has been pointed out for which further investigations are needed. The empirical and theoretical models for the mixing behavior of the different phases of bubble column reactors have also been reviewed.     

INVITED REVIEW HYDRODYNAMIC AND MIXING MODELS FOR BUBBLE COLUMN REACTORS

The knowledge of the flow patterns of each phase of bubble column reactors is of considerable importance for the rational design and scale-up. The hydrodynamic models for the liquid phase have been reviewed. The models have been based on some form of pressure balance or energy balance. These two approaches have been compared and recommendations have been made regarding the range of applicability of the individual models. A comparison between the predicted and the experimental liquid velocities has been presented whenever possible. The range of variables has been pointed out for which further investigations are needed. The empirical and theoretical models for the mixing behavior of the different phases of bubble column reactors have also been reviewed.