三相淤浆床冷态特性研究—气体—石腊油—催化剂系统

本文研究了气体－石腊油－催化剂三相体系在淤浆床反应器中的流体力学特性，考察了各种因素对气含率和压降的影响，并回归得到如下关联式：εｇ＝０．１１５２ｕｇ＾０．４１ｃｓ＾０．０９３ρ＾０．０１８。     

三相淤浆床冷态特性研究──空气─水─石英砂系统

本文研究了空气─水─石英砂三相淤浆床的流体力学特性．同时回归山含气率与其影响因素的关联式：εｇ＝０．０４９７ｕｇ１．０３７Ｃｓ－０．２５７．本文为研究三相淤浆床甲醇合成提供了流体力学数据。     

合成气制二甲醚三相淤浆床反应器气含率

引　言二甲醚是近年来国内外竞相开发、性能优越的碳一化工产品 .二甲醚不仅是从合成气制汽油、低碳烯烃的重要中间体 ,而且也是多种化工产品的重要原料 .同时由于二甲醚具有优良的燃烧性能和高的辛烷值 ,作为柴油的替代品日益引起人们的普遍关注 .随着对环境和生态平衡保护力度的加大 ,二甲醚的作用和地位将越来越重要 .与传统的采用固定床反应器以甲醇为原料脱水生成二甲醚的生产工艺相比 ,以煤或天然气为原料 ,通过合成气在三相淤浆床反应器中一步法合成二甲醚新工艺具有巨大的优越性 .三相淤浆床反应器流体力学性质十分复杂 ,目前还不能…     

三相淤浆床甲醇合成反应器大型冷模研究

以空气－水－催化剂和空气－液体石蜡油－催化剂两种系统为对象,研究了内置垂直管束式换热器三相淤浆床甲醇合成反应器的流体力学性质－－平均气含率、床层压降、固体完全悬浮的临界表观气速。考察了各种因素对流体力学性质的影响。并得到关于气含率的经验关联式：εＧ／（１－εα）＾４＝０．００５７４４〔ｕＧμＬ／σ〕＾０．１０〔１＋ｃｓ／〔１－ｃｓ／ｐｓ〕σＬ＋ｃｓ〕＾－１．７３。     

三相携带床的流体力学特性研究

研究了空气一水-黄沙三相系统在携带床反应器中的流体力学特性。反应器直径0．07m。实验考察了表观气速Ug、表观浆液流速UsL、固含率εs等因素对气含率εg和床层压降△P的影响以及三相携带床的操作特性。回归实验数据得到气含率及床层压降与各因素的关联式为εg=0.4084U△P=5783．672U研究结果为三相携带床工业反应器提供了流体力学依据。     

三相淤浆床甲醇含成反应器大型冷模研究

以空气-水-催化剂和空气-液体石蜡油-催化剂两种系统为对象,研究了内置垂直管束式换热器三相淤浆床甲醇合成反应器的流体力学性质──平均气含率、床层压降、固体完全悬浮的临界表观气速。考察了各种因素对流体力学性质的影响,并得到关于气含率的经验关联式：     

三相淤浆床反应器的连续化研究——内部过滤法

在热态条件下,采用的内过滤装置性能稳定,可以用作连续淤浆鼓泡搅拌釜的液固分离。研究表明,单釜连续可以逐级模拟多釜串联连续过程,这种多釜串联过程的开发,具有一定实际意义。     

再分布板和径向挡板对淤浆鼓泡床流体力学特性的影响

研究了在以空气-水-石英砂为实验体系的淤浆鼓泡床中加入内构件?再分布板和径向挡板对床层气含率和固含率的影响,并与不加内构件的情况进行了对比. 实验结果表明,再分布板可明显提高床层的平均气含率,且开孔孔径越小,作用越显著;但径向挡板的作用不明显;再分布板和径向挡板均可改善气含率和固含率的轴向分布,且不会大幅度增加压降. 通过对Smith关联式进行修正,得到了带有再分布板的淤浆鼓泡床中床层平均气含率的经验关联式.     

液相法三相淤浆床甲醇合成技术

液相法三相淤浆床甲醇合成技术是一种使用三相淤浆床反应器将合成气转化为甲醇的生产新技术。与传统生产工艺相比，三相淤浆床甲醇合成工艺具有单程转化率高，出口甲醇浓度高；床层等温，反应条件优良；温度易于控制，换热简单；生产的技术经济指标优良等优点，因此成为一种应用前景非常广阔的新兴甲醇生产新技术。     

Catalyst mixing in bubble column slurry reactors

The reported experimental data of Pandit and Joshi (1984) on axial and radial steady-state catalyst concentration in a semibatch bubble column slurry reactor is interpreted by the dispersion model. The elliptic partial differential equation with its associated boundary conditions is solved analytically for catalyst concentration by the method of separation of variables. The proposed model adequately fits the experimental data.     

Survey of heat transfer mechanisms in a slurry bubble column

Heat transfer mechanisms in the bulk and distributor regions of a slurry bubble column are investigated based on the measurements of local heat transfer in a 0.28 m diameter Plexiglas column. The gas, liquid and solid phases used are oil‐free compressed air, tap water and 35 μm glass beads. The slurry concentration and superficial gas velocity are varied from 0 to 40 vol% and 0.05 to 0.30 m/s respectively. Measurements have been made with a fast response heat flux probe which provided local instantaneous heat transfer coefficients. The time‐averaged heat transfer coefficients in the bulk region were on average about 50% higher than the distributor region of the column. The wall region heat transfer coefficients are well predicted by the correlation of Deckwer et al. (1980). Heat transfer mechanism in column centre can be adequately described by the consecutive film and surface renewal model.     

浆态床鼓泡反应器中气含率的分布

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。     

Liquid-Solid mass transfer in a slurry bubble column and a gas-liquid-solid three-phase fluidized bed

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.     

Effects of sparger height and orifice orientation on solids dispersion in a slurry bubble column

The effects of gas distributor height and the orientation of its orifices are investigated on solids dispersion and gas holdup profiles in a three-phase slurry bubble column. The height of the distributor was varied to cover locations from near column bottom to above the settled solids bed height. The orifice orientations were changed from upward facing to downwards facing directions. The measurements were conducted in a Plexiglas column of 0.15 m ID and 2.5 m height. The gas phase was oil-free compressed air while tap water was used as liquid phase. Glass beads with an average particle diameter of 35 μm and density of 2450 kg/m³ constituted the solid phase. The settled bed height was about 0.4 m which provided an average slurry concentration of about 15% (v/v) when all solids were dispersed. Both axial and column average phase holdups were measured. Effects of sparger location, gas jets formation and liquid circulation patterns on gas holdups and solids dispersion are analyzed. Empirical correlations are developed to relate sparger location to solids dispersion as a function of gas velocity. Optimum sparger height and orifice orientation is proposed based on the measurement of this study.     

Gas hold-up in non-newtonian solutions in a bubble column with internals

Bubble characteristics and gas hold-up were studied in a two phase (air-aqueous CMC solution) bubble column provided with helical coils and straight tubes as internals. The effects of superficial gas velocity, rheological properties, and volume fraction covered by the internals, on gas hold-up were studied. Hold-up values determined directly and by simultaneous pressure drop measurements matched well. Enhancement of gas hold-up values up to 55 per cent was achieved in systems using internals. The gas hold-up results were also compared with the values obtained from correlations reported in the literature.     

Experimental study of a cocurrent upflow packed bed bubble column reactor: pressure drop, holdup and interfacial area

Gas–liquid interfacial areas have been determined by means of chemically enhanced absorption of CO₂ into DEA in a packed bed bubble column reactor with an inner diameter of 156 mm. The influence of the gas velocity and particle diameter on the interfacial areas, pressure drops and liquid holdups has been investigated. For both packings the limiting values of the gas velocities have been determined above which the interfacial areas and liquid holdups stabilize. In particular gas channelling has been found, which is less pronounced in the bed of larger particles.     

CFD modeling of slurry bubble column reactors for Fisher-Tropsch synthesis

Industrial bubble column reactors for Fischer-Tropsch (FT) synthesis include complex hydrodynamic, chemical and thermal interaction of three material phases: a population of gas bubbles of different sizes, a liquid phase and solid catalyst particles suspended in the liquid. In this paper, a CFD model of FT reactors has been developed, including variable gas bubble size, effects of the catalyst present in the liquid phase and chemical reactions, with the objective of predicting quantitative reactor performance information useful for design purposes. The model is based on a Eulerian multifluid formulation and includes two phases: liquid-catalyst slurry and syngas bubbles. The bubble size distribution is predicted using a Population Balance (PB) model. Experimentally observed strong influence of the catalyst particles concentration on the bubble size distribution is taken into account by including a catalyst particle induced modification of the turbulent dissipation rate in the liquid. A simple scaling modification to the dissipation rate is proposed to model this influence in the PB model. Additional mass conservation equations are introduced for chemical species associated with the gas and liquid phases. Heterogeneous and homogeneous reaction rates representing simplified FT synthesis are taken from the literature and incorporated in the model.Hydrodynamic effects have been validated against experimental results for laboratory scale bubble columns, including the influence of catalyst particles. Good agreement was observed on bubble size distribution and gas holdup for bubble columns operating in the bubble and churn turbulence regimes. Finally, the complete model including chemical species transport was applied to an industrial scale bubble column. Resulting hydrocarbon production rates were compared to predictions made by previously published one-dimensional semi-empirical models. As confirmed by the comparisons with available data, the modeling methodology proposed in this work represents the physics of FT reactors consistently, since the influence of chemical reactions, catalyst particles, bubble coalescence and breakup on the key bubble-fluid drag force and interfacial area effects are accounted for. However, heat transfer effects have not yet been considered. Inclusion of heat transfer should be the final step in the creation of a comprehensive FT CFD simulation methodology. A significant conclusion from the modeling results is that a highly localized FT reaction rate appears next to the gas injection region when the syngas flow rate is low. As the FT reaction is exothermal, it may lead to a highly concentrated heat release in the liquid. From the design perspective, the introduction of appropriate heat removal devices may be required.