摘要:

AbstractThe flow around an accelerating spherical particle of diameter ranging from 50 to 200 m̈m is studied in the range of Reynolds number between 0.1 and 100. The flow around the sphere is assumed to be laminar and two‐dimensional axisymmetric. The calculated drag coefficient is compared with the theoretical predictions of added mass term and Basset history term. Appropriate corrections for those two terms are proposed as function of the acceleration rate and the particle diamet

ISSN:0008-4034    

DOI:10.1002/cjce.5450710602

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

年代:1993

数据来源: WILEY

摘要:

AbstractAccurate determinations of excess pressure losses at the entry and exit of capillary flows are essential for rheological characterization of fluids by capillary viscometry. A modification of Bagley's end correction method is presented which accounts for the effects of slight variations in the diameters of the tubes of varying length used in the evaluations. The method was applied to capillary flows of dilute aqueous Polyox solutions using the three homologues WSR 301, Coagulant and FRA of Polyox. The excess pressure losses were found to increase with increase in the apparent shear rate, polymer concentration and tube diameter.

ISSN:0008-4034    

DOI:10.1002/cjce.5450710603

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe flooding behaviour of a 150‐mm diameter Wirz‐II extraction column has been investigated for six different liquid‐liquid systems. Normally, flooding occurred by phase inversion but when the density difference was low could also occur by entrainment of dispersed‐phase drops at the continuous‐phase exit. Empirical expressions for flooding velocities and holdup at flooding are derived in terms of the operating variables, column geometry and physical properties of the liqui

ISSN:0008-4034    

DOI:10.1002/cjce.5450710604

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper reports an experimental study on the effect of oil viscosity on the rheology of oil‐in‐water (o/w) emulsions with added solids. Four oils having a viscosity range of 0.0024 to 306 Pa . s were used. The size ratio of the solids to oil droplets was varied from 2 to 16. The addition of smaller size solids to the emulsions yielded a higher viscosity than that of larger solids at the same solids volume fraction. However, when the solids were sufficiently large such that the emulsions behaved as a continuous phase towards the solids, the viscosity of the emulsion‐solids mixtures tended to be independent of the solids size.The critical size ratio of the solids to oil droplets, above which the emulsions behaved as a continuous phase towards the solids, increased with the oil viscosity. The critical size ratio varied between 3 a

ISSN:0008-4034    

DOI:10.1002/cjce.5450710605

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

年代:1993

数据来源: WILEY

摘要:

AbstractOxygen transfer in aqueous solutions of CMC, xanthan gum, and polyacrylamide in a vessel equipped with a helical ribbon screw impeller and a multi‐orifice ring sparger was studied. The KLa values obtained were comparable to those reported for radial flow impellers, but they are more representative of the oxygen transfer in the bulk of the liquid because of a more homogeneous mixing and absence of dead zones. Dimensionless correlations including the effect of the physical properties of the fluids, and those of operating conditions were developed. A dimensionless correlation for each fluid is propose

ISSN:0008-4034    

DOI:10.1002/cjce.5450710606

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe continuous pyrolysis of CANMET coprocessing residue in argon/hydrogen plasma was studied for the temperature range 2700 to 3670 K using an induction plasma torch. Hydrogen was injected into the argon plasma tailflame at molar concentrations ranging from 0 to 23 %. The residue was continuously fed in liquid form to a laboratory‐scale reactor specially built for the study. The residue flow rate ranged from 6 to 9 g/min. A maximum of 10% of the residue pyrolysed with up to 90 % conversion to gaseous hydrocarbons. The rate of residue pyrolysis and the rate of formation of the gaseous products were found to be strongly dependent on the rate of heat transfer at the residue surface. The only gaseous products detected were acetylene, ethylene and methane. Some soot was produced, but no liquid hydrocarbons were detecte

ISSN:0008-4034    

DOI:10.1002/cjce.5450710607

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effectiveness of benzyl diethyl phosphite as a coke inhibitor during naphtha pyrolysis was investigated in a tubular reactor at 1073 K and atmospheric pressure. Significant reduction in the coking rate was achieved by adding benzyl diethyl phosphite to the feed. The effect of toluene, methylcyclohexane, l‐octene and carbon disulfide on the rate of coke formation was also investigated. Toluene enhanced the rate of coke formation significantly, whereas with methylcyclohexane and l‐octene the increase was less appreciable. Carbon disulphide decreased the amount of coke deposited initially, but with increasing run time the asymptotic coking rates were found to be higher than for straight‐run naphtha. The yields of propylene, 1,3‐butadiene and butenes increased on addition of carbon dis

ISSN:0008-4034    

DOI:10.1002/cjce.5450710608

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe main objective of this investigation is to obtain experimental data for the sulfuric acid hydrolysis of cotton and mechanically pretreated cotton fibres. These data indicate that some glycosidic bonds of cellulose have very high accessibility to catalytic ions. It was also shown that milling increases the accessibility of some glycosidic bonds of cellulose and decreases the volume of the crystalline regions of cotton. From the glucose yield versus time data, it was found that the effect of milling on the rate of cellulose depolymerization depends on the reactivity and accessibility of the glycon rings of cellulose. It was also found that at 1OO°C, the rate of cellulose depolymerization was not affected by the extraction of cotton wax and this was related to a rolling up process of cotton wax caused by melting. The kinetic constants of glucose degradation and cellobiose hydrolysis have been determined for the stochastic simulation of cellulose depolymerization which is the subject of the second part of this work

ISSN:0008-4034    

DOI:10.1002/cjce.5450710609

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe solid state reduction kinetics by carbon monoxide of sodium sulfate mixed with sodium titanate are studied in a thermogravimetric system at 670‐750°C. It is found that the reduction of this mixture is much faster than that of pure sodium sulfate. The conversion‐time curves of the model mixtures are sigmoidal in shape and well described by the nucleation and growth kinetic model. The activation energy is 420 kJ/mol. The influence of the CO and CO2, concentration, mass fraction of sodium titanate and addition of sodium sulfide catalyst are investigated. Based on the present experiments and literature results, a mechanism is proposed for the CO reduc

ISSN:0008-4034    

DOI:10.1002/cjce.5450710610

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

年代:1993

数据来源: WILEY

摘要:

AbstractAn analytical reaction engineering model, recently presented by van Ede et al. (1992), which describes formation of inhibiting products associated with the growth of immobilized biofilms, is extended to describe simultaneous production associated with biofilm maintenance. The model accounts for both the metabolic rate controlling behaviour of an inhibitory product in the biofilm, and the effect of diffusion limitation in the transport of this product or a substrate, on the biofilm thickness.Simple criteria are presented to check the applicability of the model in the case of true Monod kinetics.As a potentially industrially important example, ethanol production by Zymomonas mobilis is treated.

ISSN:0008-4034    

DOI:10.1002/cjce.5450710611

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

年代:1993

数据来源: WILEY