新型规整网孔填料萃取性能实验研究

为了得到一种新型规整网孔填料在萃取中的传质效率,在Φ50 mm的填料塔中,采用质量分数为30%磷酸三丁酯(TBP)-煤油-醋酸-水中等界面张力的物系,测定了3种不同齿度新型网孔规整填料的液液萃取性。与Φ10 mm鲍尔环相比,在相同的操作条件下新型网孔规整填料的表观传质单元高度比鲍尔环降低15%—45%。固定连续相流速,随着分散相流速的增大,表观传质单元高度变小,传质效率高。固定分散相流速,随着连续相流速的增大,表观传质单元高度变大,传质效率变低。在所测物系条件下,小网孔具有高的传质效率。     

气-液-液萃取的流体力学研究

在液-液萃取过程中,提高分散相的表面更新速率可有效提高萃取的传质效率。研究发现,在萃取过程中使用气体搅拌可以增加液液之间的接触面积,促进液相内的湍动和循环。本文研究了气-液-液三相下油滴的流动形态,并对不同填料的流体力学性能进行了测定。实验结果表明,气相速度的增加可导致气含率、液含率的增加,从而提高分散相在填料萃取塔中的停留时间,在一定的速度范围内明显降低萃取的表观传质单元高度,极大地强化传质效果。通过与散装填料对比,发现规整填料更利于强化萃取效果,其液泛速度平均增加25%。     

气体搅拌萃取过氧化氢实验研究

在内径为50 mm的筛板塔内,研究了空气-水-蒽醌工作液三相体系萃取过氧化氢过程.萃取温度为40℃,空气和分散相的表观流速分别为(1.31～3.22)×10-3m·s-1和(1.27～1.70)×10-3 m·s-1,分散相和连续相的表观流速之比为50:1.结果表明,在普通液-液萃取过氧化氢过程中引入气体作搅拌,可减小分散相的液滴直径,增大相际接触面积,明显提高萃取效率,降低萃余相中过氧化氢的含量.传质单元高度随气体表观流速的增加而降低,传质系数随气体表观流速的增加而增大.     

气-液-液萃取传质效率的研究

在液-液萃取过程中,提高分散相的表面更新速率可有效提高萃取的传质效率.研究发现,在萃取过程中使用气体搅拌可以增加液液之间的接触面积,促进液相内的湍动和循环.据此,本文在气-液-液萃取条件下对不同填料的传质性能进行了测定.实验表明,通入气相后分散相液滴呈现稳定的“油包气”空心状态,这种结构大大降低了分散相液滴的传质层厚度,减小了传质距离,极大地强化传质效率.在适宜气速下,气-液-液萃取效率较传统萃取效率提高20％～40％.通过与散装填料对比,发现规整填料更利于强化萃取效果,传质效率提高约50％.     

一种用于液液萃取的网架规整填料

通过一种新型网架规整填料与Φ12mm的鲍尔环填料的萃取对比试验,测定了该填料和Φ12mm的鲍尔环填料在不同操作条件下的表观传质单元高度,论述了该填料在液液萃取应用上的高效性,并对其工业化应用进行了展望。     

新型网架规整填料的传质性能

对一种新型网架规整填料用于萃取时的传质效率进行了实验研究。在Φ50mm的填料萃取塔中,选用煤油–苯甲酸–水和30%TBP(煤油)–乙酸–水两种不同界面张力的物系,测定了该填料和Φ10mm的鲍尔环填料在不同操作条件下的表观传质单元高度。扣去影响因素,网架填料的表观传质单元高度至少会比鲍尔环填料低25%,而网架填料的堆积密度仅为鲍尔环的38%。同时对影响传质的因素进行了分析,并针对该填料的特点,提出了优化设计原则。     

气相扰动下高效萃取填料的开发及性能研究

针对气液液三相萃取,开发出一种新型高效开窗导流式规整填料,该填料片是在板波纹规整填料片的波峰、波谷处开设导流窗口,从而增加气相的流通空间和扰动频率,进而增加液滴的破碎-聚并频率。实验测定了新型填料的流体力学性能及传质性能。实验结果表明:随气相速度的增加,填料的液泛速度降低,传质单元高度先减小后增加。新型开窗导流式规整填料可有效提高分散相的滴膜交替流动频率,增加传质效果,在相同的操作条件下,新型规整填料的流体力学效果和传质效果较超级扁环填料平均提高11%和44.7%。     

立装规整填料的性能研究

以空气-水为工质研究了立装规整填料的流体力学性能;利用CO_2-空气-水体系研究其传质性能,并与相同试验条件下的平装规整填料进行对比。结果表明,在相同条件下,2者的压降没有明显变化,但立装填料比平装填料的壁流量和液相总传质单元高度分别降低了10.7%和17.4%,其流体力学和传质性能均优于平装填料。     

气体扰动萃取过氧化氢的试验研究

在内径为50mm的筛板塔内,研究了蒽醌工作液-过氧化氢-水体系的气体扰动萃取过程。萃取温度为40℃,空气和分散相的表观流速分别为（0～3．22）mm／s和（1．27～1．70）mm／s,分散相和连续相的表观流速之比为50：1。结果表明,在过氧化氢萃取塔中引入扰动气体,增大了分散相滞液率,提高了总板效率,降低了萃余相中过氧化氢的含量。     

气液液三相体系中的气液传质特征

选取CO2-K2CO3/KHCO3为吸收体系,次氯酸钠为催化剂,甲苯、异戊醇为第2液相,应用Danckwerts图来同时确定液侧传质系数KL和界面面积a,通过实验研究了分散第2液相的加入对气液传质的影响。实验结果表明,随着分散相体积分数φ(1%—10%)的增大,或分散相形成的液滴直径的减小,以及传质组分在分散相和连续相中溶解度的比值m(即传质组分在实验体系的分配系数)增加,或在二相间的相对扩散系数增加时,可显著增强气液传质,为气液液三相体系的系统化研究提供了实验依据。     

HD低温蒸发系统中填料蒸发器传质传热的分析

通过研究系统中填料蒸发器的蒸发传质传热过程以及两相流动特性，采用计算流体力学（computational fluid dynamics，CFD）中离散相与连续相耦合的方法来模拟规整填料内部通道的蒸发传质传热过程，实现了填料蒸发器中两相传质传热的过程以及液滴流动的可视化，为研究气液两相在规整填料内的流动提供了一种模拟方法。通过与实验结果的比较，最终选用RNG k-ε湍流模型来分析规整填料内部气液两相传质传热以及流动情况。数值模拟研究了规整填料板间距对填料内部气液两相传质传热以及液滴运动影响，发现随着板间距的增大，填料内部压力降逐渐降低，出口空气中水蒸气的含量不断减小，液滴蒸发速率降低，液滴进出口质量差减小，气相出口温度逐渐降低，蒸发传质传热效率降低。随着气速的增大，出口空气中水蒸气的含量不断减小，液滴蒸发速率增加，气相出口温度降低，气液两相传质传热效率降低。     

规整填料在高压精馏条件下的传质性能

Performance of Mellapak 250Y and 350Y corrugated structured packing in distillation applications at pressures ranging from 0.3 to 2.0MPa is analysed by using HTU-NTU method.These data are obtained in distillation column with 0.15m diameter operated with n-butane/n-pentane system at total reflux.In considering the axial backmixing effects.the height of an overall gas phase transfer unit,HTUOG,is divided into two parts.One part represents the height of an overall gas phase transfer unit,without backmixing, designated as HUTOG,and the other part,designated as the height of a backmixing unit(HBUO),accounts for the backmixing effects.The HTUOG is evaluated from the measured concentration profile of n-butane in liquid phase.The HBUO obtained experimentally is correlated in terms of the properties of the materials being separated and the equivalent diameter of the structured packing.Our result shows that HBUO varies from 0.12 to 0.34m as pressure increases from 1.0 to 1.9MPa.It indicates that the overall efficiency of the structured packing decreas gradually at high pressure,as a result of the vapor backmixing.     

HOLDUP MEASUREMENT IN A SCHEIBEL EXTRACTION COLUMN

ABSTRACT The total holdup of a dispersed organic phase in a rotary-agitated Scheibel liquid-liquid extraction column of the first type is studied experimentally. The column is 2 inches in diameter and contains 11 stages with a 4-inch height packed section and a 1-inch height mixing section. The packed section is made of stainless steel wire mesh packing with a 93.74% free area and acts as a settler for the coalescence of droplets. Three systems are studied: benzene/water, methyl isobutyl ketone (MIBK)/water and 20% TBP-80% kerosene/1?M nitric acid. The effects of different phase flow rates and rotation speeds (300-670?rpm) on the dispersed phase holdup are investigated. The results show that the holdup increases with increasing dispersed phase flow rate but does not vary with continuous phase flow rate. For benzene, the holdup is large at low rotation speeds and decreases with increasing rotation speed until a minimum holdup is reached, after this transition point, the holdup increases with increasing rotation speed. This phenomena is analogous to that found in a pulse column. For MIBK and 20% TBP-kerosene, the holdup always increases with rotation speed in our experimental range and the transition point is not observed as M in benzene. This is attributed to the much larger interfacial tension of benzene-water as compared with the other 2 systems.     

Investigation of hydrodynamic and mass transfer of mercaptan extraction in pulsed and non-pulsed packed columns

We investigated the hydrodynamic behavior and mass transfer characteristics of a pilot-scale conventional packed bed extraction column of mercaptan removal from liquid propane. The extraction column was filled with pall rings structured packing where mercaptan was extracted from the continuous phase to the dispersed phase, accompanied by a chemical reaction in propane-mercaptan-caustic system. The pulsing was introduced into the column to enhance the mass transfer rate. Hydrodynamic parameters such as hold up, flooding velocity and mean drop size were studied together with the effect of chemical reaction on increasing mass transfer performance. Finally, the mass transfer and axial mixing coefficients were obtained from the optimization of data by ADM. It was found that at the pulsation intensity from 0.003 to 0.007 m/s, the maximum mass transfer and minimum axial mixing occurred and it can be concluded that pulsation improves the efficiency of mass transfer just at low intensities.     

CFD Study on the Local Mass Transfer Efficiency in the Gas Phase of Structured Packing

Visualization of local mass transfer coefficients over the dry surface of corrugated‐sheet structured packing is essential for optimizing the existing geometry of structured packing and for improving mass transfer efficiency to develop new structured packing. The local flow patterns between packing sheets and the gas‐phase mass transfer coefficient at each point over the surface are illustrated by employing a wall‐surface reaction model. Different turbulence models are utilized, i.e., a standard κ‐? model and three different low‐Re‐κ‐? models. The numerical calculation results with the Lam‐Bremhorst low‐Re‐κ‐? turbulence model is found to agree well with experimental data. There are three similar regions with enhanced mass transfer efficiency in each mass transfer unit cell of structured packing.     

用可视化方法实验研究规整填料的局部传质(英文)

A chromochemical reactive mass transfer technique has been employed to study local mass transfer characteristics of structured packing. This technology adopted by experiment is an Ammonia Adsorption Method (AAM) that yields the surface distribution of transferred mass by analyzing the color distribution on a filter paper with the results of the color chemical reaction. A digital image processing technology is applied for data visualiza-tion. The three-dimensional plot of the local mass transfer coefficients shows that there exist three peak values on different positions of a unit cell of structured packing. In order to improve mass transfer efficiency of the structured packing, one piece of baffle is added between packing sheets. As a result, the average mass transfer coefficient in-creases by (10-20)% and the pressure drop decreases by (15-55)%.     

Drop formation mass transfer coefficients in extraction columns

Mass transfer coefficients (MTC) of single liquid drops during drop formation period, in the presence and absence of down flow of the continuous phase, were measured in an extraction column. The effects of formation time, needle size, and flow rates of the continuous and dispersed phase were evaluated experimentally. It was found that the drop size increases with increasing formation time and decreasing down flow of the continuous phase. The mass transfer coefficients are the largest in the initial stages of drop formation when convection is the most significant. Both flow rates have a significant effect on the rate of the mass transfer, and the convection caused by the dispersed phase flow is more important than the continuous phase. The mass transfer coefficient and the degree of extraction increase with increasing down flow rate of the continuous phase.