摘要:

AbstractLongitudinal dispersion data are reported for a straight tube (internal dia. 1¼′ (2.77 cm)). Three binary gas systems were examined over the regime 3 × 102

ISSN:0008-4034    

DOI:10.1002/cjce.5450470201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe imperfect pulse method is a powerful technique for experimental analysis of chemical engineering flow systems. The authors have employed this method in studies of holdup and mixing in gas‐liquid fluidized beds. In the present paper are discussed two problems connected with reduction of the experimental data obtained in such studies.Tailing is a phenomenon that may seriously affect the accuracy of mixing coefficients determined by the imperfect pulse method. Accurate methods of data reduction, based upon analysis of moments, have been developed, and their applicability is demonstrated by analysis of experimental data.Interphase transfer of tracer material is of particular importance in investigations of gas phase mixing in a gas‐liquid system where absorption of tracer gas into the liquid phase normally takes place. A semiempirical method is described for correction of the experimental data in such ca

ISSN:0008-4034    

DOI:10.1002/cjce.5450470202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe axial dispersion of liquid in a 12‐in. turbulent‐bed contactor has been investigated for three packing sizes: ½‐in., 1‐in. and 1½‐in. The gas and liquid flow rates were varied from 500 to 2700 lb./(hr.)(sq. ft.) and from 1500 to 11,000 lb./(hr.)(sq. ft.) respectively. The transient response technique usingKClsolution as the tracer was employed for this purpose.The experimentally determined residence‐time distribution curves were interpreted by means of a one‐dimensional dispersion model. The axial dispersion coefficient,DL, was found to increase with increasing gas flow rate, liquid flow rate, or packing size. In terms of Peclet number (NPe= ūdp/DL), the present data showed thatNPewas dependent on Reynolds number (N Re L, =dpūρ/μ), Gallileo number (NGa=dp3ρ3g/μ2), and reduced gas mass velocity (Δ = (G‐Gmf)/Gmf), but the ratio of the Peclet number for a turbulent contactor to the Peclet number for a fixed‐bed contactor,NPe/NPeo, depended only on Δ, and the diameter ratiodp/dt. A correlation ofNPe/N

ISSN:0008-4034    

DOI:10.1002/cjce.5450470203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractMutually dependent heat and mass transfer for laminar gas flow in a parallel‐plate channel is investigated analytically. Sublimation occurs at one of the channel walls, while the other wall is nonsubliming. Both walls are thermally insulated from the external environment. The analysis of the problem requires simultaneous treatment of the energy and mass diffusion equations, with coupling provided by the boundary conditions. Mathematical expressions are derived and numerical results are presented for various quantities that characterize the heat and mass transfer processes. Comparisons are made with the case of symmetric transfer (i.e., both walls actively participating). In general, unsymmetric transfer is found to slow down the axial development of the temperature and mass fraction field

ISSN:0008-4034    

DOI:10.1002/cjce.5450470204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe porosity of a fluidized bed at any superficial velocity may be calculated by Richardson and Zaki's method if the terminal velocity of a representative particle is known. This terminal velocity can be calculated under any operating conditions by Beranek's atmospheric elutriation criterion.Porosities were measured at 331 superficial velocities in fluidized beds of cracking catalyst, using hydrogen, nitrogen and argon at pressures of 300 to 800 p.s.i.g. as the fluidizing media. It was postulated that the “largest significant particle” was representative for beds fluidized with high‐pressure gases such as these.The porosities at these same velocities were calculated using Beranek terminal velocities of the “largest significant particles” in Richardson plots. A 16.6% standard deviation was found in the values of the calculated porosities when compared with the measur

ISSN:0008-4034    

DOI:10.1002/cjce.5450470205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractSome structural properties of packed bed systems on both the local and overall scales which are available in the literature and of interest in chemical engineering applications are discussed. Regular and random packings of uniformly sized spheres are initially analyzed as a basis for the later examination of the more general case of random packed beds containing particles of various sizes and shapes, with or without restraining surfaces.

ISSN:0008-4034    

DOI:10.1002/cjce.5450470206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractTwo progression models which can be employed to represent flow systems with varying degree and mode of mixing along the direction of flow such as a shallow fluidized bed, radial flow reactors, and short tubular reactors, etc. are proposed. Residence time distributions are derived from the standpoint of stochastic processes. The use of progression models is illustrated with a second order, isothermal reaction.

ISSN:0008-4034    

DOI:10.1002/cjce.5450470207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractA modified group solution model for liquid mixtures is presented. The model differs from previous models in that the Bronsted‐Koefoed congruence principle is used to describe the effect of molecular size. The model has been tested for mixtures involving paraffin hydrocarbons, alcohols and water at low pressures. Such systems involve binary mixtures of the groups methylene and hydroxyl, and are reasonably represented by the model.Data presented enable the approximate equilibrium properties of such solutions at low pressures to be predicted at 40°C and 90°C. Interpolation and reasonable extrapolation from these temperatures should be satisfact

ISSN:0008-4034    

DOI:10.1002/cjce.5450470208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe kinetics of ethane hydrogenolysis catalyzed by a commercial 58% nickel‐on‐kieselguhr catalyst were studied at 1 atm. and from 220° to 250°C. The kinetic data could be fit by a simple power rate equation that is a limiting case of a more general equation. The reaction rate of ethane was first order with respect to ethane and —2 order with respect to hydrogen. A possible reaction mechanism is discussed. The apparent activation energy was 46.4 kcal. Ethane/hydrogen ratios as high as 1:1 were studied without catalyst deactivation. Kinetic data were obtained in a novel stirred‐tank catalyti

ISSN:0008-4034    

DOI:10.1002/cjce.5450470209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractAcetone, methyl ethylketone, methyl isopropylketone and toluene were oxidized separately in the liquid phase by oxygen at 140°C, under 15 atm partial pressure of oxygen with 1 wt % di‐ ter‐ butylperoxide. The main product is acetic acid. Acetone is much less reactive than the other two ketones. Cooxidations of binary mixtures composed of a ketone and toluene were performed under the same experimental conditions. In these cooxidation systems, the three ketones have similar reactivities. The discrepancy between the relative reactivities of the ketones oxidized alone or with toluene is interpreted by the theory of the branched chain oxidations, and indicates the great influence of the chain branching coefficients and the stability of the free peroxy radicals on the total rate of oxidation of the ket

ISSN:0008-4034    

DOI:10.1002/cjce.5450470210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY