VOLUMETRIC MASS TRANSFER COEFFICIENT BETWEEN SLAG AND METAL IN COMBINED BLOWING CONVERTER

The effects of operation parameters of combined blowing converter on the volumetric mass transfer coefficient between slag and steel are studied with a cold model with water simulating steel, oil simulating slag and benzoic acid as the transferred substance between water and oil. The results show that, with lance level of 2.1m and the top blowing rate of 25000Nm3/h, the volumetric mass transfer coefficient changes most significantly when the bottom blowing rate ranges from 384 to 540Nm3/h. The volumetric mass transfer coefficient reaches its maximum when the lance level is 2.1m, the top blowing rates is 30000Nm3/h, and the bottom blowing rate is 384Nm3/h with tuyeres located symmetrically at 0.66D of the converter bottom.

Experimental determination of gas holdup and volumetric mass transfer coefficient in a jet bubbling reactor

The hydrodynamics and mass transfer characteristics of a lab-scale jet bubbling reactor(JBR)including the gas holdup,volumetric mass transfer coefficient and specific interfacial area were assessed experimentally investigating the influence of temperature,pH and superficial gas velocity.The reactor diameter and height were 11 and 30 cm,respectively.It was equipped with a single sparger,operating at atmospheric pressure,20 and 40℃,and two pH values of 3 and 6.The height of the liquid was 23 cm,while the superficial gas velocity changed within 0.010-0.040 m·s^(-1)range.Experiments were conducted with pure oxygen as the gas phase and saturated lime solution as the liquid phase.The liquid-side volumetric mass transfer coefficient was determined under unsteady-state oxygen absorption in a saturated lime solution.The gas holdup was calculated based on the liquid height change,while the specific interfacial area was obtained by a physical method based on the bubble size distribution(BSD)in different superficial gas velocities.The results indicated that at the same temperature but different pH,the gas holdup variation was negligible,while the liquid-side volumetric mass transfer coefficient at the pH value of 6 was higher than that at the pH=3.At a constant pH but different temperatures,the gas holdup and the liquid-side volumetric mass transfer coefficients at 40℃were higher than that of the same at 20℃.A reasonable and appropriate estimation of the liquid-side volumetric mass transfer coefficient(kla)in a pilot-scale JBR was provided which can be applied to the design and scale-up of JBRs.

A convenient method for measuring gas-liquid volumetric mass transfer coefficient in micro reactors

The research on gas-liquid multiphase reactions using micro reactors is becoming increasingly widespread, given their excellent mass transfer performance. Establishing an accurate and reliable method to measure the gas-liquid mass transfer performance of micro reactors is crucial for evaluating and optimizing the design of micro reactor structure. In this paper, the physical absorption method of aqueous solution-CO_(2) and the chemical absorption method of sodium carbonate solution-CO_(2) were proposed. By analyzing the chemical reaction equilibrium during the absorption process, the relationship between the mass transfer of CO_(2) and the solubility of hydroxide ions in the solution was established, and the total gas-liquid mass transfer coefficient was immediately obtained by measuring the p H value. The corresponding testing platform and process have been established based on the characteristics of the proposed method to ensure fast and accurate measurement. In addition, the chemical absorption method takes into account temperature factors that were not previously considered. The volumetric mass transfer coefficient measured by these two methods is in the same range as those measured by other methods using the same microchannel structure in previous literature. The methods have the advantages of low equipment cost, faster measurement speed, and simpler procedures, which can facilitate its wide application to the evaluation of the mass transfer performance and hence can guide the structure optimization of microchannel reactors.

Gas–liquid mass transfer and flow phenomena in the Peirce–Smith converter: a water model study

A water model with a geometric similarity ratio of 1：5 was developed to investigate the gas-liquid mass transfer and flow charac- teristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume （Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coeffi- cient）, and gas utilization ratio （t/） were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and n steadily increased. When the converter was rotated clockwise, both Ak/F and t/increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these para- meters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3.h-1 and 10°, respectively.

Catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-Mn-Cu/γ-Al2O_(3) in a rotating packed bed

This study investigated catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-MnCu/γ-Al_(2)O_(3)(Cat)in a rotating packed bed(RPB)for the first time.The results showed that the value of the overall decomposition rate constant of ozone(K_(c))and overall volumetric mass transfer coefficient(K_(L)a)are 4.28×10^(-3) s^(-1) and 11.60×10^(-3) s^(-1) respectively at an initial pH of 6,βof 40,Co3(g)of 60 mg·L^(-1)and Q_(L) of 85 L·h^(-1) in deionized water,respectively.Meanwhile,the K_(c) and K_(L)a values of Fenhe water are0.88×10^(-3) s^(-1) and 2.51×10^(-3) s^(-1) lower than deionized water,respectively.In addition,the K_(c) and K_(L)a values in deionized water for the Cat/O_(3)-RPB system are 44.86%and 47.41%higher than that for the Cat/O_(3)-BR(bubbling reactor)system,respectively,indicating that the high gravity technology can facilitate the decomposition and mass transfer of ozone in heterogeneous catalytic ozonation and provide some insights into the industrial wastewater.

多孔板鼓泡塔流动与传质特性数值模拟

采用Euler-Euler双流体模型对安装不同数量的水平多孔板的鼓泡塔内气液两相流动及传质特性进行数值模拟研究,并探究了不同表观气速条件对鼓泡塔内气含率、气泡直径分布和气液传质系数的影响。结果表明,不同数量的多孔板和不同位置的多孔板都会影响气含率的分布;随着多孔板的数目增加,鼓泡塔液相上方区域的气含率增加,但影响区域有限;安装多孔板后,鼓泡塔内径向位置的平均气含率变化明显,出现“M”形状的分布。不同表观气速下,未安装多孔板的鼓泡塔内直径为1~2mm的微小气泡占比超过30%;安装多孔板后,微小气泡占比明显增加;气液传质系数在中心区域(径向无量纲为-0.5~0.5)较为平缓,波动不大。最后将模拟计算得到的气液体积传质系数与Akita的关联式计算值进行比较,本文计算结果略高。

生物反应器气液传质强化的研究进展

生物反应器是生物过程工程的核心设备,应用广泛,已实现了巨大的经济价值,但仍然存在较低的气液传质效率,这是降低生物转化效率的关键因素。本文综述了生物反应器中基于溶质渗透模型的传质机制及常用的体积传质系数(k_(L)a)测量方法,剖析了气含率(Φ)、气泡直径(d B)、扩散系数(D_(L))、湍动能耗散率(ε)、液相密度(ρ)、流体黏度(μ)以及表面张力(σ)等因素对k_(L)a的影响机制,论述了最新的气液传质强化方法及应用进展,以期为生物反应器的气液传质强化提供研究思路。

沼气提纯过程中醇胺溶液吸收CO_2传质性能

醇胺溶液吸收CO2是沼气提纯领域重要的研究课题。在实验填料吸收塔中,以乙醇胺（MEA）、二乙醇胺（DEA）为吸收剂,研究了吸收剂浓度、进气流量、CO2浓度、进液温度对吸收过程转化率η、吸收速率N以及气相总体积传质系数KGae的影响。结果表明,吸收剂浓度增加可有效提高η、N及KGae;进气流率增加,η逐渐降低,N先增加后降低,KGae先增加后降低最终趋于稳定;随着CO2浓度增加,η和KGae不断降低,N逐渐增加;随着进液温度升高,η和KGae均先升高后降低;MEA、DEA的最佳进液温度在40～60℃之间,并随CO2负载量增大而逐渐降低。研究结果对于醇胺溶液吸收法沼气提纯技术的研究开发和实际应用有参考作用。

喷雾强化空气冷却器的实验研究

文献上常采用有效膜传热系数的方法来考虑管外水膜传热传质的综合效果，用析湿系数考虑对空气增湿降温的效果，这种基于对数平均温差或ε～ＮＴＵ方法对湿式空冷器进行热计算是比较粗糙和近似的．本文基于Ｍｅｒｋｅｌ的焓差法，用容积散质系数的方法对水膜的传热传质进行分析．在实验过程中改变了空气质流量以及喷水强度，测得有关数据，整理得出βｘｖ值．用多元回归方法得出的βｘｖ关联式。

填料塔中钠碱溶液吸收低浓度SO2的体积传质系数

在填料吸收塔中测定和计算了钠碱溶液吸收烟气中低浓度SO2的体积总传质系数(KGa),并研究了进口气体中SO2浓度、气体流量、吸收液喷淋密度以及溶液中Na+浓度对体积传质总系数的影响。结果表明,进口气体中SO2浓度、气体流量及吸收液喷淋密度对KGa的影响较大;随着进口气体中SO2浓度的增大,KGa逐渐减小,而随着进口气体流量及吸收液喷淋密度的增大,KGa逐渐增大;吸收液中Na+浓度对KGa的影响较小。

溴化锂溶液除湿器性能的实验研究

对逆流、散装填料、LiBr溶液的除湿器进行实验研究,实验过程中溶液流量为800～1600 L.h-1,入口溶液浓度为49%～54%,温度为28～41℃,空塔气速为0.39～0.96 m.s-1,入口空气湿度为10～21 g.kg-1。采用除湿量和体积传质系数来描述除湿性能,分析了溶液和空气入口参数对除湿性能的影响,得出平均体积传质系数为1.0 kg.m-3.s-1,液气比为2.5～3时可获到较好的除湿效果。比较了不同填料的除湿性能,鲍尔环填料除湿效果较好。同时对除湿过程进行了能量守恒分析,表明实验测量数据的准确性。实验结果为溶液除湿系统的性能分析及设计提供了依据。

蒸发式冷却器的传热传质试验研究

对蒸发式冷却器传热传质试验结果的数据处理进行了讨论，重点是它的容积散质系数以及工艺水到水膜的传热系数．介绍了试验台和各测试仪表，给出了对两个试件的测试结果，整理了βｘｖ和Ｋ的变化规律。

氨水细喷雾吸收CO_2的体积总传质系数

二氧化碳减排已经成为国际关注的焦点问题,近年来,二氧化碳捕集与封存技术(capture and storage of CO2,CCS)被认为是减少CO2排放的有效途径。氨水作为一种新的吸收剂得到普遍关注。为了为进一步的工业设计提供参考依据,该文采用喷雾塔对氨水细喷雾吸收CO2进行试验研究,考察氨水流量和氨水浓度对CO2脱除率的影响,测定了氨水细喷雾吸收CO2的体积总传质系数,研究氨水浓度、氨水流量、进口气体流量、CO2进口浓度和温度对体积总传质系数的影响。实验结果表明,体积总传质系数随着气体流量、氨水流量、氨水浓度的升高而增大,随着CO2进口浓度升高略微下降;当温度低于40℃,体积总传质系数随反应温度升高而增加,至40℃达到最大值。研究发现氨水浓度是影响体积总传质系数的关键因素。

三相下喷式环流反应器的传质性能

在三相非牛顿型流体体系中，对下喷式环流反应器传质特性进行了实验研究。讨论了表观气速、能量耗散速率、导流筒直径与反应器直径比、喷嘴直径、导流筒下端距反应器底部的距离、固体装填量、羧甲基纤维素钠（ＣＭＣ）溶液浓度及其流变特性对它的影响。实验结果表明，容积传质系数随表观气速和能量耗散速率的增加有所增加，在实验条件下，发现最优的导流筒直径与反应器直径比在０．４～０．４５这一范围、固体装填量大约为３％（体积百分比）、导流筒下端距反应器底部的距离为０．０８ｍ左右。同时提出了容积传质系数的经验关联式。

高压搅拌釜中H_2、CO在不同液体介质中的溶解度和体积传质系数的研究

使用高压搅拌釜，应用气体间歇吸收技术，在温度３７３～５７３Ｋ、压力１．０～４．０ＭＰａ，转速８００ｒ／ｍｉｎ的实验条件下，测定了Ｈ_２、ＣＯ在液体石蜡，正二十八烷烃和ＦＴ３００蜡中的溶解度和体积传质系数。实验结果表明Ｈ_２、ＣＯ在３种液体介质中的溶解度和体积传质系数均随温度和压力的升高而增加，随液体介质分子量增加而减少。同时获得了溶解度随温度变化的关联式和气体在液体中的溶解热数据。

复吹转炉钢-渣间容量传质系数的水-油模型

在熔池直径 880mm、深 2 5 8mm的冷态模型中 ,利用水模拟钢水、机油模拟渣、苯甲酸模拟钢 渣间传输物质来研究熔池直径 5 2 85mm、深 15 4 5mm的复吹转炉吹炼工艺参数对钢 渣间容量传质系数的影响。结果表明 ,枪位 35 0mm ,顶吹流量 117m3 /h ,底吹流量 1 6 8m3 /h至 2 36m3 /h时 ,传输物质苯甲酸的容量传质系数变化最显著 ,在采用枪位 35 0mm ,顶吹流量 14 0m3 /h ,底吹流量 1 6 8m3 /h ,底枪布置方式为 8孔对称布置在 0 6 6直径的圆上时 ,传输物质的容量传质系数最大。

鼓泡床反应器内流动与传质行为的研究进展

总结了有关浆态鼓泡床反应器内流动、混合用气液传质特性的研究成果,详细地介绍了鼓泡床反应器内气含率、液速、液体轴向扩散系数、传质系数的测量方法,阐述了鼓泡床反应器性能的主要影响因素,如系统压力、温度、气体表观气速、液体性质及固含率等对流动、液相混合和传质特性的影响,并对鼓泡床反应器的应用前景进行了详述。

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。

气升式环流反应器的研究进展

环流反应器在工业上正得到越来越广泛的应用,对其进行深入研究对于此类反应器的设计与放大具有重要意义。对环流反应器的流动、混合及传质特性参数随表观气速、液相物性、系统压力和反应器尺寸等操作条件的变化关系进行了综述。介绍了各特性参数的测量方法,并指出了这些方法的优缺点及可能存在的误差。对环流反应器的流动、混合及传质特性的数学模型进行了评述,并在此基础上对环流反应器研究的发展前景进行了展望。

填料塔中混合胺吸收二氧化碳的研究

在填料塔中考察了常压下混合胺吸收剂[20%乙醇胺(MEA)+2%N-甲基二乙醇胺(MDEA),20%羟乙基乙二胺(AEE)+2%MDEA]对CO2的吸收与解吸效果。同时测得了AEE+MDEA混合胺体系吸收剂脱除空气中体积分数约10%的CO2的体积总传质系数KGav的近似值,并考察了进口气体中CO2摩尔流量、气体流量、液体流量等因素对KGav的影响。实验结果表明,AEE+MDEA吸收效果明显好于MEA+MDEA,并且二者解吸效果相同;KGav随CO2摩尔流量、气体流量、液体流量增大而增大。