摘要:

AbstractA uniflow cyclone is being studied to achieve the separation of hot solids from the gaseous products of ultra‐rapid fluidized (URF) processes. An experimental method with hot wire probes was developed to study the gas flow around the gas outlet, where the solids exit. The vortex penetration in the solids exit could be determined. The presence of solids greatly reduced the vortex penetration in the uniflow cyclone. Restricting gas circulation around the gas outlet dramatically impaired the cyclone collection efficiency. Therefore, good cyclone performance requires a proper design below the gas outle

ISSN:0008-4034    

DOI:10.1002/cjce.5450700201

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

年代:1992

数据来源: WILEY

摘要:

AbstractA model for calculating the minimum spouting flowrate and pressure drop in a conical spouted bed has been developed and described in our previous paper (Hadžismajlovi et al., 1986). In the present work, this model was examined at a wider range of experimental conditions and it was found that measured and predicted values of the minimum spouting flowrate and pressure drop differed by about 10.3% and 20.0%, respectively.It is shown that the spouted bed in a conical column is stable when the inlet tube diameter is less than 25 particle diameters

ISSN:0008-4034    

DOI:10.1002/cjce.5450700202

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

年代:1992

数据来源: WILEY

摘要:

AbstractA method for predicting the transverse motion of a granular bed in a rotary cylinder is proposed, based on a non‐Newtonian rheological model of the pseudo‐plastic type, i.e. with a flow behaviour index (n) between 0 and 1. For a good simulation of bed motion, the model must be able to adequately reproduce the bed velocity profile in both the upper (downward flowing) and the lower (upward moving) zones. It is shown that to do so there is the need to adjust not only the consistency indexKbut even more importantly the flow behaviour index,n. The mass and momentum conservation equations are solved by the CFD code FLUENT. The model is applied to the simulation of the motion of an alumina bed and the computed results compared with experimental d

ISSN:0008-4034    

DOI:10.1002/cjce.5450700203

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe liquid‐liquid‐plate contact angles of several plate materials were measured using a “preferential wetting method” proposed by the authors. The adhesional work (ISL), calculated on the basis of contact angles was utilized to evaluate plate wettability. The experimental results indicate that different plate materials affect differently plate wettability. The plate wettability of stainless steel in an aqueous phase was observed to be different from that in an organic phase. The droplet diameter in the mixer‐settler region of operation of a pulsed perforated‐plate extraction column using several different plate materials, was measured. An empirical correlation of mean droplet diameter: dp= 0.222(af/lSL1/3)−0.13is proposed except for alumina plates with dispersed aqueous ph

ISSN:0008-4034    

DOI:10.1002/cjce.5450700204

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

年代:1992

数据来源: WILEY

摘要:

AbstractOn étudie le rǒle de la viscosité dépendant linéairement de la température sur la convection laminaire le long d'une plaque verticale soumise à un flux de chaleur constant. L'analyse est basée sur la résolution numérique des équations de couche limite instationnaire utilisant une procédure implicite de différences finies. On présente les profils de vitesse de température et du nombre de Nusselt à l'état permanent et dans la période transitoire. En régime transitoire, les champs de vitesse et de température atteignent une valeur maximale avant de décroǐtre légèrement jusqà leurs valeurs permanentes. Ce phénomène appelé “overshoot”, peut ětre amplifié ou atténué selon les valeurs que l'on donne au paramètre sans dimension caract

ISSN:0008-4034    

DOI:10.1002/cjce.5450700205

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

年代:1992

数据来源: WILEY

摘要:

AbstractActivated carbon was found more active than molécular sieve 13X and silica gel in adsorbing 1,1,2 trichloro‐1,2,2 trifluoroethane (CFE). Batch adsorption experiments were carried out with activated carbon to adsorb CFE at 15, 25 and 30°C. The adsorption isotherms of CFE on activated carbon were of the Langmuir type:q(C) =qmKC/ (1 +KC) whereqmandKwere evaluated for the three temperatures. The measured bulk concentration‐time data were interpreted equally well with the surface diffusion model and the pore diffusion model; for the former model the surface diffusivity increased with increasing initial CFE concentration, and for the latter the pore diffusivity was independent upon the initial CFE concentr

ISSN:0008-4034    

DOI:10.1002/cjce.5450700206

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

年代:1992

数据来源: WILEY

摘要:

AbstractDans cet article, les performances de quatre membranes tubulaires d'alumine SCT de diamètres de pores différents (0.2, 0.8, 1.4 et 2.0 μm respectivement) ont été étudiées pour différentes conditions de pression, vitesse tangentielle et concentration de fluide. L'analyse des résultats obtenus (débits de perméation au solvant pur des membranes propres ou conditionnées, débits d'ultrafiltration, taux de rétention des espèces protéiques) au moyen de modèles simples (théorie de la filtration, théorie du film) amène les auteurs à émettre des hypothèses originales quant au mode de fonctionnement particulier de chaque élément filtrant. En particulier, il est établi que les mécanismes de mise en place et le type du colmatage évoluent fortement d'une membrane à l'autre. Enfin, les auteurs concluent que, pour les conditions expéri‐mentales choisies, c'est la membrane de 0.2 μm qui en règie générate permet d'atteindre les débits d'ultrafi

ISSN:0008-4034    

DOI:10.1002/cjce.5450700207

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

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper focuses on two‐phase (e.g., fluid‐solid catalyst) chemical reactors where one phase participates in the feed and effluent, first order chemical reactions proceed in the other phase and linear, species‐dependent, interphase transport connects the phases. A class of reactors exists in which the Laplace transform of the dynamic reaction/interphase transport equations reduces to essentially that of an effective set of first order reactions amongst effluent phase species only, in an imaginary single phase reactor.This result bears on scale‐up: Since the imaginary reactor simply scales with the usual residence time distribution, so too do reactors of this class scale with its analog. This easily measurable analog turns out to be just the non‐adsorbing tracer experiment. Significantly, certain reactors outside of this class do not scale likewise, even with first order chemistry; an example illustrates.The class in question includes, but is not limited to, fixed bed and Berty (CSTR) reactors. The analysis allows design inferences for two‐phase reactors, including flu

ISSN:0008-4034    

DOI:10.1002/cjce.5450700208

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

年代:1992

数据来源: WILEY

摘要:

AbstractEffects of temperature (250−275°C), pressure (0.1‐1.03 MPa) and feed gas exposure velocity (139‐722 μm/s) were studied on carbon monoxide hydrogenation in a tube‐wall reactor using plasma‐sprayed cobalt catalyst. The specific catalytic activity and hydrocarbon selectivity increased with an increase in pressure and temperature and a decrease in the exposure velocity. The results showed that the formation of olefins especially ethylene and propylene was favored at low pressures, low temperatures and high exposure velocities. This catalyst was found to be selective for C5+hydrocarbons (27‐34 wt.%) at increased pressures (0

ISSN:0008-4034    

DOI:10.1002/cjce.5450700209

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

年代:1992

数据来源: WILEY

摘要:

AbstractA mathematical model was developed to predict the performance of Fischer‐Tropsch Synthesis over cobalt catalyst in a tube‐wall reactor. Comparison was made between model predictions and previous experimental results (part 1 of this paper) for pressures 0.35‐1.03 MPa, temperatures 250−275°C, and exposure velocities 139‐722 μ/s. The agreement was good. The model predicts an increase in methanation activity with temperature. Carbon monoxide and hydrogen conversions, and water and carbon dioxide concentrations increase along the reactor axis. With an increase in exposure velocity, hydrocarbons and carbon dioxide production increase, but water production decreases. However, the water‐gas shift activity increases continuously along the reactor axis. The model is based on two‐dimensional transport equations, and employs the orthogonal collocation method in its numeri

ISSN:0008-4034    

DOI:10.1002/cjce.5450700210

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

年代:1992

数据来源: WILEY