摘要:

AbstractA one‐dimensional model of pulse or plug flow is proposed. This type of flow is observed at high mass ratios of solids to gas and requires gas velocities orders of magnitude less than dilute phase systems.Plug stability criteria are examined by considering the axial interparticle stresses within single plugs and the effect of the radial transmission of these stresses on wall friction. Establishment of the fluid pressure gradient within the plug and the existence of a settled layer of solids in the interplug space are shown to be important requirements.These concepts are used in the formulation of an empirical pressure drop equation which is used in the correlation of experimental data. Comparison of predicted and experimental values is reasonable for the air‐sand system considered.The model should be of value in the planning and interpretation of future experimental stud

ISSN:0008-4034    

DOI:10.1002/cjce.5450600501

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn a two‐phase concentric jet the second phase, consisting of solids, influences the development of the jet and the effect of its presence needs to be assessed quantitatively. An experimental study of such a jet with particles in the secondary stream was therefore undertaken. It is seen that particles enhance the mixin

ISSN:0008-4034    

DOI:10.1002/cjce.5450600502

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

年代:1982

数据来源: WILEY

摘要:

AbstractHeat transfer between a wall and a two‐dimensional fluidized bed has been studied. The fluidized bed remains isothermal for thicknesses as small as 8 mm, with significant values of the heat transfer coefficient up to the wall of the column.The bubbling properties in the two‐dimensional bed have been recorded using a rapid cine camera. These data have been used to test several heat transfer models. A convenient agreement has been obtained when taking into account a wall contact resistance t

ISSN:0008-4034    

DOI:10.1002/cjce.5450600503

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe impulse response technique for the injection of a tracer has been applied to both liquid phases in a pilot plant sized reciprocating plate extraction column of the type introduced by Karr. The responses obtained have been interpreted using the piston flow model, and employing three analysis techniques to determine the Péclet number, Pe, and the residence time, π, namely the moments method, the least‐squares method in the time and frequency domains and the Vergnes' method.The least‐square method was found to give the most coherent results, even for the dispersed phase, because this method is less sensitive to instrument drift (noise) than the two other methods.The piston flow model successfully described and correlated the longitudinal mixing in the continuous phase, and fairly well for the dispersed

ISSN:0008-4034    

DOI:10.1002/cjce.5450600504

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetic parameters of a biological reactor, operating under monoculture and monosubstrate conditions, have been determined. Pure cultures ofNocardia corallinaandPseudomonas fluorescensspecies have been used with phenol as the only organic carbon source. The experimental runs have been carried out both in a batch and in a continuous stirred reactor.The batch results have been interpreted by zero order kinetics in phenol and first order kinetics in biomass. The kinetic‐constants have also been calculated. The activation energy has been determined only for theNocardiaspecies. Using this strain, the continuous reactor, working without biomass recycle, has confirmed the first order kinetics with respect to biomas

ISSN:0008-4034    

DOI:10.1002/cjce.5450600505

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

年代:1982

数据来源: WILEY

摘要:

AbstractCopper has been added as a second metal to a nickel‐dispersed‐on‐alumina methanation catalyst. Compared with the nickel catalysts without copper, the initial methanation activity was reduced drastically but the tendency to deactivate with time‐on‐stream was much less. There were also less carbon deposition and less sintering of metal particles with the copper‐adde

ISSN:0008-4034    

DOI:10.1002/cjce.5450600506

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

年代:1982

数据来源: WILEY

摘要:

AbstractWe present evidence which indicates that the nature of the active sites is the same for amorphous catalysts as it is for crystalline alumina silicate cracking catalysts. The only differences we find in the various cracking catalysts lie in the total concentrations of active sites and in the ratio of Bronsted to Lewis sites.In view of this, and because even zeolites have only a fraction of their cationic sites active in cumene cracking, we suggest that it is possible that a silica alumina catalyst could exist that is more active by as much as an order of magnitude than any catalyst presently available for cumene cracking.

ISSN:0008-4034    

DOI:10.1002/cjce.5450600507

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

年代:1982

数据来源: WILEY

摘要:

AbstractA detailed analytical study of the products of cumene cracking over amorphous silica alumina shows that the mechanism of cracking over these catalysts is identical to that observed over crystalline LaY and HY at various levels of exchange. Additional analytical details are developed in this work and are used to elaborate on the previously proposed reaction network for this reaction. In particular we find that hydrogen and propane appear as secondary products in the cracking reaction network. We also find that within the limits of our measurement all the observed coke is formed from product propylene.

ISSN:0008-4034    

DOI:10.1002/cjce.5450600508

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

年代:1982

数据来源: WILEY

摘要:

AbstractAn analysis of a tube‐wall reactor with varying volume is considered under turbulent flow conditions for the case in which both the kinetic and diffusional resistances are important. The implicit molar flux expression is approximated by three successive approximations and the mass and energy balances are combined to obtain a single explicit design equation. This equation takes the form of a simple numerical integration which requires only physical and chemical properties of the inlet gas and reactor operating conditions. The method also predicts the temperature and heat flux along the reactor length. Comparison of the model predictions with a limited number of previous experimental results is goo

ISSN:0008-4034    

DOI:10.1002/cjce.5450600509

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

年代:1982

数据来源: WILEY

摘要:

AbstractSynthetic residual waters from dairies have been subjected to a laboratory‐scale treatment study.A thoroughly‐stirred continuous‐flow reactor involving no recirculation of the biomass has been used. The operation‐control two parameters have been (a) the mean residence time of the biomass and (b) the bioreactor temperature. The variables have been (i) the substrate removal expressed in terms of the chemical demand in oxygen (D.C.O.) and (ii) the biomass production expressed in terms of volatile suspended matters.The Monod model has adequately described the system behavior. The kinetic constantsk, kd. Y, K, have been determined at 5, 15 and 25°C. The values of the substrate maximum rate of assimilation per biomass unit (k) and of the specific rate of the biomass deterioration rate (kd) have characterized the constants according to the Arrhenius Law in the range covered. The values of the half‐rate constantKshave been high at the above‐mentioned three temperatures in comparison with the conventional values. The maximum coefficient of the yield (Y) has varied little with the

ISSN:0008-4034    

DOI:10.1002/cjce.5450600510

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

年代:1982

数据来源: WILEY