共查询到19条相似文献,搜索用时 671 毫秒
1.
2.
3.
4.
陈迎 《化学反应工程与工艺》2017,33(3)
羰基合成反应一般采用射流鼓泡反应器,该类反应器气液混合的方式采用射流而非机械搅拌,其主要优点是结构简单、制作简便、维护费用低。研究该类型反应器的传质系数对于其设计、优化及放大操作均具有重要意义。本研究采用缩颈式圆形喷嘴,以动态溶氧法对射流鼓泡反应器内的液相体积传质系数进行测定,考察了表观气速、射流雷诺数对液相体积传质系数的影响。研究发现,随气速增大液相体积传质系数的变化规律为先增大而后保持不变。维持表观气速不变,随雷诺数增加液相体积传质系数增大,但当表观气速小于0.0012 m/s时,雷诺数对传质改善较小。建立了液相体积传质系数的经验关联式,当气体输入功率占总功率56%时,液相体积传质系数最大,气体鼓泡和液体射流的协同作用最强。 相似文献
5.
引言 鼓泡床是一种重要的气液或气液固多相反应器.液体循环流动是鼓泡床的一个重要流体力学特征,从20世纪50年代人们就开始对此进行了比较系统的实验研究[1-6].这个特征对鼓泡床的流体返混行为、气含率、气液界面积以及传热传质系数都有很大影响,特别是液体返混行为可以由液体循环特性直接决定.如何准确地描述和预测鼓泡床中的液体流速沿径向的分布,关系到鼓泡床反应器的设计、放大和优化.因此,许多年来它一直是人们致力探讨的重要课题之一[7-8]. 相似文献
6.
为了解浆态床鼓泡反应器中气含率的分布规律,在浆态床鼓泡反应器冷模试验装置中,以空气-液体石蜡-氧化铝微球为试验介质对装置内部的气含率进行研究。利用压差法研究了表观气速、浆液固含量等操作条件对反应器床层总体气含率的影响,利用光纤探针法研究了浆态床反应器不同操作条件对局部气含率的影响,总结了反应器内部气含率的分布规律,并由此对工业浆态床鼓泡反应器的设计进行了研究。结果表明:浆态床反应器的总体气含率随表观气速的增大而增大,固体细颗粒的加入能适当降低总体气含率;在反应器底部,分布器对气体的均布作用明显,但表观气速的增大能够弱化分布器的作用;在反应器的中上部气含率不受分布器的影响,沿反应器径向呈现"中间高,边缘低"的分布趋势;在工业费托浆态床中,表观气速不宜低于0.12 m/s,内过滤系统适宜设置于反应器中上部靠近器壁的位置。 相似文献
7.
喷嘴结构对射流鼓泡反应器的混合和传质性能具有重要的影响。以空气-水作为模拟介质,使用双探头电导探针、电解质示踪法和动态溶氧法,对比研究了缩径式圆形喷嘴和旋扭三角形喷嘴对射流鼓泡反应器中气泡尺寸分布、平均气含率、液相混合时间和气液传质系数的影响规律。实验发现,随着气速或液体射流Reynolds数的增大,两种喷嘴对应的平均气含率、液相混合时间和气液传质系数具有相同的变化规律;与缩径式圆形喷嘴相比,采用旋扭三角形喷嘴的射流鼓泡反应器中气泡尺寸更小,平均气含率更高,宏观混合时间更短;当气体输入功占总输入功比例超过20%时,喷嘴结构对气液传质系数的影响较小,当气体输入功占总输入功比例小于20%时,旋扭三角形喷嘴的气液传质性能优于缩径式圆形喷嘴。研究结果可为工业射流鼓泡反应器喷嘴结构的优化提供理论指导。 相似文献
8.
9.
本文开发了一种新型微孔膜气体分布器,并对使用该分布器时鼓泡塔反应器内气液传质性能进行了研究。实验结果表明,使用这种新型膜气体分布器可以得到细小均匀的气泡,较大幅度地增大了气液传质比表面积,从而大大强化了反应器的传质能力。 相似文献
10.
射流鼓泡反应器通过耦合射流与鼓泡两种作用机制实现了气液理想混合,避免了甲醇羰基化制醋酸工艺中搅拌内构件的腐蚀。射流、鼓泡的耦合加剧了混合过程的复杂性,阻碍了对该反应器气液流动、传质、混合的认识。文章分别综述了均相体系射流混合、鼓泡反应器流动规律及喷射式气液反应器流动规律。结果表明,混合时间、气泡直径及气含率分别用于表征射流和鼓泡混合效果,气液顺流喷射反应器性能需同时考虑液相体积传质系数。因此,射流鼓泡反应器的研究需以上述所有参数作为特征参数,通过实验和模拟剖析反应器内部气液传质及射流与鼓泡的协同机制。 相似文献
11.
以空气-水-黄沙以及空气-液体石蜡-黄沙两种系统为对象,在常压下用溶氧仪研究了采用小孔式及金属烧结板两种分布器的高固含率三相淤浆反应器的气液传质特性,以及固含率和表观气速等因素对容积气液传质系数kLa的影响,最后得到采用上述两种气体分布器的高固含率三相淤浆床关于容积气-液传质系数的经验关联式。实验证明,金属烧结板具有更好的气液传质特性。 相似文献
12.
The gas-liquid mass transfer of H2 and CO in a high temperature and high-pressure three-phase slurry bubble column reactor is studied. The gas-liquid volumetric mass transfer coefficients kLa are obtained by measuring the dissolution rate of H2 and CO. The influences of the main operation conditions, such as temperature, pressure,superficial gas velocity and solid concentration, are studied systematically. Two empirical correlations are proposed to predict kLa values for H2 and CO in liquid paraffln/solid particles slurry bubble column reactors. 相似文献
13.
Mass transfer in a slurry bubble column reactor was examined. A theoretical correlation for liquid-phase mass transfer coefficient was developed using a combination of Higbie's penetration theory and the Einstein-Li periodic viscous sublayer model. The proposed correlation predicts that the liquid-phase mass transfer coefficient decreases with an increase of the yield stress of slurries. The measurement of mass transfer rates was conducted in a 40-L bubble column reactor. The slurries containing low-density particles were simulated by aqueous carboxypolmethylene solutions. Satisfactory agreement was found between the proposed correlation and the experimental data. 相似文献
14.
Experimental study on bubble behavior and CFD simulation of large-scale slurry bubble column reactor
Haoyi SUN Tao LI Weiyong YING Dingye FANG 《Frontiers of Chemical Engineering in China》2010,4(4):515-522
Slurry bubble column reactors (SBCR) is a three-phase fluidized reactor with outstanding advantages compared with other reactors
and is difficult to scale-up due to lack of information on hydrodynamics and mass transfer over a wide range of operating
conditions of commercial interest. In this paper, an experiment was conducted to investigate the bubble behavior in SBCR with
a height of 5600 mm and an interior diameter of 480 mm. Bubble rise velocity, bubble diameter, and gas holdup in different
radial and axial positions are measured in SBCR using four-channel conductivity probe. Tap water, air, and glass beads (mean
diameter 75–150 μm) are used as liquid, gas, and solid phases, respectively. It shows that hydrodynamic parameters have good
regularity in SBCR. Moreover, a commercial computational fluid dynamics (CFD) package, Fluent, was used to simulate the process
in SBCR. The simulations were carried out using axi-symmetric 2-D grids. Data obtained from experiment and CFD simulation
are compared, and results show that the tendency of simulation is almost uniform with the experiment, which can help to obtain
further understanding about multiphase flow process and establish a model about the synthesis of alcohol ether fuel in SBCR. 相似文献
15.
Fundamental characteristics of hydrodynamics and mass transfer have been measured in an air lift slurry reactor with a draft tube. The solid suspension capacity, i.e., the critical solid holdup, the gas holdup and the volumetric gas-liquid mass transfer coefficient were measured in the two draft tube columns of 0.1485 and 0.10?m in diameter. Four activated carbon beads ranging in size from 0.25 to 2.19?mm in average diameter were utilized as suspended solids in the experiments.
The critical solid holdup in the draft tube slurry column is found to be much greater than that in the conventional bubble column. An empirical correlation is developed to account for the critical solid holdup behavior in the draft tube column. The gas holdup in the draft tube column agrees well with that in the bubble column. The overall gas-liquid mass transfer coefficient, k1awas measured by the oxygen probe method. The effect of solid holdup on k1a is found to be negligible in the present system. The empirical equation is developed to correlate k1a in the draft tube slurry reactor. 相似文献
16.
In this paper, a multi-scale approach is followed to study gas-liquid mass transfer in bubble columns. First, a single bubble of equivalent diameter d is considered. Its morphology and its gas to liquid relative velocity are related to the bubble diameter through the use of known correlations. Then, the gas-liquid mass transfer between the bubble and the surrounding liquid is studied theoretically. An equation describing the transport of the transferred species in the viscous boundary layer around the bubble is solved. In a second step, a bubble column of 6-10 m height is studied experimentally. The gas phase in the column is characterized experimentally by means of a gammametric technique. Finally, the two studies are linked, yielding a 1D mathematical model able to predict the gas-liquid mass transfer rate in a bubble column operated in the heterogeneous regime. 相似文献
17.
Xiao Xu Junjie Wang Qiang Yang Lei Wang Hao Lu Honglai Liu Hualin Wang 《中国化学工程学报》2020,28(12):2968-2976
As the scale of residual oil treatment increases and cleaner production improves in China, slurry bubble column reactors face many challenges and opportunities for residual oil hydrogenation technology. The internals development is critical to adapt the long-term stable operation. In this paper, the volumetric mass transfer coefficient, gas holdup and bubble size in a gas–liquid up-flow column are studied with two kinds of internals. The gas holdup and volumetric mass transfer coefficient increase by 120% and 42% when the fractal dimension of bubbles increases from 0.56 to 2.56, respectively. The enhanced mass transfer processing may improve the coke suppression ability in the slurry reactor for residual oil treatment. The results can be useful for the exploration of reacting conditions, scale-up strategies, and oil adaptability. This work is valuable for the design of reactor systems and technological processes. 相似文献
18.
Mass transfer coefficients between particles and liquids in a slurry bubble column and a three-phase fluidized bed containing small size particles were obtained with two mass transfer systems: (1) K+ –Na+ ion-exchange in cation-exchange resin bead beds, including anion-exchange resin beads as inert particles; (2) zinc dissolution by HCl in zinc-plated glass bead beds, and in beds of non-plated glass beads. Operating parameters were gas velocity, liquid velocity, particle diameter, and particle concentration. The dependence of mass transfer coefficients on these parameters is discussed from the viewpoint of the energy supplied into the systems. Correlations of the experimental data using dimensionless groups are compared to previous correlations. 相似文献