摘要:

AbstractThe correlation of axial mixing in the continuous and dispersed phases of rotating disc and asymmetric rotating disc columns is presented. Published experimental results on continuous‐phase axial mixing for both single‐ and two‐phase flows, obtained with tracer injection methods and by solute concentration profiles, are considered. The correlation developed is based on 1055 data points for 32 liquid systems obtained by 19 different investigators. The axial mixing in rotating disc columns is found to be up to 20% larger than in asymmetric rotating disc columns.Data for the dispersed phase are harder to correlate than those for the continuous phase. Since the available results are often contradictory, the correlation for the dispersed‐phase coefficient is thus less accurate than that for the continuousphase coef

ISSN:0008-4034    

DOI:10.1002/cjce.5450700112

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe objective of this work is to model the effect of simultaneous drop forward‐mixing and coalescence‐redispersion on the hydrodynamics and mass transfer efficiency of a two phase countercurrent extraction process. Based on the flow mechanism and drop size distribution in extraction columns, a novel model with a simplified sequential algorithm is developed. It is much easier to use, and computationally less expensive, than a direct simulation technique which would typically be a tedious boundary‐value iteration method. A new concept of Effective Mass Transfer Coefficient is presented, from which the effect of drop forward‐mixing and coalescence‐dispersion on extraction performance is directly evaluated from an analytical expression. The results calculated from the model are satisfactorily compared to experimental results obtained from three actual extraction system in two pulsed sieve‐plate extraction columns. The relationship between the present model and the diffusion model is discussed and a parameter transformation equation for the two mode

ISSN:0008-4034    

DOI:10.1002/cjce.5450700113

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe rate of dissolution of rock salt in drilling mud was measured as a function of flow rate and temperature under conditions simulating those in a well. A water based drilling mud, containing about 10% solids and additives was used, as well as a polymer “mud” composed of a Xanthan gum polymer solution and 5% salt, but no solids. The non‐Newtonian muds were pumped through a “slit” flow cell, with a slab of rock salt flush with one side of the cell wall. The data (including water over the same range of conditions) were described by a mass transfer coefficient, and were correlated in dimensionless form based on the theoretical solution of the analogous heat transfer problem, adapted to non‐Newtonian fluids. The non‐Newtonian properties were described by an effective viscosity, which is consistent with either the power law or Bingham plastic vi

ISSN:0008-4034    

DOI:10.1002/cjce.5450700114

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

年代:1992

数据来源: WILEY

摘要:

AbstractA semibatch, coaxial, two‐impinging‐stream (TIS) contactor was developed and tested for dissolving solid particles of sodium‐nitrate, sodium‐nitrite and urea in water. The feature of the contractor lies in the possibility of increasing and controlling the mean residence time of the particles in the reactor.The mass transfer coefficients determined in the semibatch device, where the water was in a continuous flow and the particles remained in the reactor for a certain period of time, can also be applied to a continuous TIS device. The comparison of mass transfer coefficients with values of other well‐known devices indicated that they are among the highest and that the present contactor is very effective.A physical model was established for the behaviour of the dissolving particles which yielded a two‐parameter correlation for predicting the Sherwood number as a function of the operational

ISSN:0008-4034    

DOI:10.1002/cjce.5450700115

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe gas‐liquid mass transfer in two‐phase flow through a capillary has been measured for water‐air, ethanol‐air and ethylene glycol‐air systems. A semi‐theoretical model has been developed and compared with experimental results. and a full computer simulations of the flow pattern and mass transfer using a flow simulation program have been made. The measured values are about 30% less than the calcul

ISSN:0008-4034    

DOI:10.1002/cjce.5450700116

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

年代:1992

数据来源: WILEY

摘要:

AbstractSome aspects of batch cooling crystallization in the industrial practice are analysed by computer simulations. The results indicate that without appropriate kinetics and very accurate process control, even the qualitative effects of applying controlled cooling and seeding are highly unpredictable. An increase in product size by applying controlled cooling is likely to be successful only rather randomly and the size distribution becomes broader. A linear or weakly non‐linear cooling curve usually produces larger crystals than a natural cooling curve, and a better reproducibility than a controlled cooling curve. Seeding increases both size and reproducibility, but is also likely to increase significantly the coefficient of variation of the product distribution. The product weight mean size and coefficient of variation may increase or decrease at increasing amount of seeds, depending on governing kinetic

ISSN:0008-4034    

DOI:10.1002/cjce.5450700117

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe oscillatory behaviour of the anodic dissolution of copper into an aqueous NaCl solution containing a small amount of thiocyanate ions has been studied experimentally in the absence and in the presence of a magnetic field. The latter has an inhibiting effect on the oscillation and, under specific conditions, it can fully suppress it.

ISSN:0008-4034    

DOI:10.1002/cjce.5450700118

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

年代:1992

数据来源: WILEY

摘要:

AbstractCe travail présente l'étude d'un réacteur électrochimique à matrice solide granulaire lorsque celle‐ci est placée dans un tronc conique. La solution à traiter percole le lit granulaire du réacteur en écoulement du fait de la gravité tout en lui assurant une bonne cohésion et donc une conductivité électronique satisfaisante.Les solutions numériques des équations différentielles liées aux bilans de masse et de charge permettent d'atteindre les distributions de concentration, de courant et de potentiel dans le cas où le lit granulaire est maintenu fixe. Une évolution de ces distributions expérimentales est discutée dans le cas où le lit granulaire est mis en mouvement.L'évolution des concentrations (écoulement piston) et l'influence des débits liquide et solide discutés et illustrés dans le cas de la récupération de cuivre de solutions diluées (<500 ppm) d'acide sulfurique. Un diagramme de dimensionnement pour chaque cas de perco

ISSN:0008-4034    

DOI:10.1002/cjce.5450700119

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe kinetics of ortho‐cresol ozonation in water has been studied using the film theory. At most experimental conditions investigated, the kinetic regime of the absorption has been fast pseudo first order with respect to ozone. At 30°C mass transfer plays an important role in controlling the absorption rate of ozone. The selfdecomposition reaction of ozone does not take place because of the great reactivity of o‐cresol with ozone. Reaction rate constants have been determined at pH 7 for different temperatures below 30°C. The following Arrhenius equation was obtained:kT= 2.2 × 1023exp(‐11784/T), L/mol ṁ sAt temperatures below 30°C there exists an ozone partial pressure value above which the ozone absorption kinetic regime changes to fast second order regardless of experimental

ISSN:0008-4034    

DOI:10.1002/cjce.5450700120

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

年代:1992

数据来源: WILEY

摘要:

AbstractAn optimum CFST bioreactor design equation is presented which can be used with linear growth‐associated product inhibition models. Batch experiments were performed to determineSaccharomyces cerevisiaegrowth parameters required for solving the optimum design equation.The three bioreactors were designed in decreasing volumes to achieve theoretical glucose conversions of 99.9% and 99.99%. At steady state, the bioreactors appeared to reach the theoretical conditions as long as the flowrates were held equal or slightly below the optimum conditions. At very low flowrates, biomass death was observed in downstream reactors while at high flowrates, the theoretical conversions were not achieved. The experimental results confirm that optimally designed bioreactors can offer lower processing volumes to achieve high substrate conversions as compared to single CFST bioreactor

ISSN:0008-4034    

DOI:10.1002/cjce.5450700121

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

年代:1992

数据来源: WILEY