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2007年04月04日

【期刊论文】MFI沸石中MaxweII-Stefan扩散系数与覆盖率的关系

刘辉, 张舟, 刘辉, 陈标华

化工学报2005年11月第56卷第11期/Journal of Chemical Industry and Engineering (China) November 2005, Vol. 56, No. 11,-0001,():

-1年11月30日

摘要

基于描述多孔介质中表面扩散的 Maxwell-Stefan(M-S)方程,结合本文动力学Monte Carlo(KMC)模拟及文献中分子动力学(MD)模拟数据,提出了MFI沸石中M-S扩散系数与覆盖率依赖关系的新表达式。该关系式考虑了分子间相互作用以及饱和吸附覆盖量对扩散系数与覆盖率依赖关系的影响,用于预测强受限组分CF4、 弱受限组分CH4 以及中度受限组分Xe等7种单组分在 MFI沸石中的 M-S扩散系数时,结果较现有其他关系式更为合理。

扩散系数, 覆盖率, Maxwell-Stefan方程, MFI沸石, 动力学 Monte Carlo

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2007年04月04日

【期刊论文】Mass transfer from Taylor bubbles rising in single capillaries

刘辉, C.O. Vandu, H. Liu, R. Krishna

C. O. Vandu et al. Chemical Engineering Science 60 (2005) 6430-6437,-0001,():

-1年11月30日

摘要

Gas–liquid mass transfer from Taylor bubbles rising in 1, 2 and 3mm diameter capillaries of circular and square cross-sections was investigated for air–water system. The liquid-phase volumetric mass transfer coefficient kLa was obtained from experimental oxygen absorption dynamics. The experimental kLa values are in good agreement with the model developed by van Baten and Krishna (2004.Chemical Engineering Science 59, 2535–2545), with the additional assumption that the

Mass transfer, Taylor bubbles, Vertical capillary, Penetration model, Monolith reactors

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2007年04月04日

【期刊论文】Identification of hydrodynamic similarity in risers of circulating fluidized beds

刘辉, HUI LIU, BIAOHUA CHEN, CHENGYUE LI

H. Liu et al. Chemical Engineering Science 55 (2000) 2741-2744,-0001,():

-1年11月30日

摘要

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2007年04月04日

【期刊论文】Hydrodynamics of Taylor Flow in Vertical Capillaries: Flow Regimes, Bubble Rise Velocity, Liquid Slug Length, and Pressure Drop

刘辉, Hui Liu, Chippla O. Vandu, and Rajamani Krishna

Ind. Eng. Chem. Res., Vol. 44, No. 14, 2005,-0001,():

-1年11月30日

摘要

Two-phase flow hydrodynamics in vertical capillaries of circular and square cross sections were experimentally studied, using air as the gas phase and water, ethanol, or an oil mixture as the liquid phase. The capillary hydraulic diameters ranged from 0.9 mm to 3 mm, with the superficial gas and liquid velocities covering a span of 0.008-1 m/s, which is typical of that obtained in monolith reactors. Using a high-speed video camera, four distinct flow regimes were observed within the range at which experiments were conducted: bubbly, slug-bubbly, Taylor, and churn flows. Annular flow was observed at excessively high gas and low liquid flow rates, well beyond those of interest to this study. Based on the definition of a two-class flow regime, the combination of two parameterssthe slip ratio (S) and the ratio of the superficial gas velocity to two-phase superficial velocity (UG/UTP)-was observed to be suitable for determining the transition from homogeneous flow to nonhomogeneous flow. The influence of capillary geometry, capillary hydraulic diameter, and fluid properties on bubble rise velocity (Vb) were investigated and determined to be of little significance. Furthermore, a new and simplified correlation for predicting Vb and, by implication, the gas holdup (∈G) was proposed. Liquid slug lengths were also experimentally studied, using a correlation that was developed to estimate them. Pressure drop experiments were also performed, and the peculiar phenomenon of negative frictional pressure drops was observed at very low liquid velocities. By defining a new dimensionless quantitysthe pressure factor, FE-a flow-regime-dependent method for estimating the total pressure drop in two-phase vertical capillary flows was developed.

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2007年04月04日

【期刊论文】HIGH PURITY SEPARATION OF EUTECTIC MIXTURES IN A CONTINUOUS MOVING CRYSTAL BED COLUMN CRYSTALLIZATION

刘辉, Q. LI, H. LIU, B. WANG and Y. ZHANG

Trans IChemE, Vol. 81, Part A, November 2003,-0001,():

-1年11月30日

摘要

This paper presents new experimental results on the separation of an o-dichlorobenzene/p-dichlorobenzene mixture in a continuous moving crystal bed crystallization column under the top-fed operation mode. Local concentration distributions of the binary eutectic mixture were investigated as a function of the feed composition, reflux ratio, crystal bed height, and internal stirring speed. It is demonstrated that the key factor that is decisive to the separation capability of column crystallization is the reflux ratio. The experiments showed that product purities can easily exceed 99.0% over a wide range of feed compositions, 68-94 wt%, reflux ratios, 1.0-4.7, and crystal bed heights, 200-900 mm within a column of 50 cm i.d.

crystallization, fractional, continuous, mass transfer, purification.,

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    北京化工大学,北京

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