摘要:

AbstractA rotating drum with lifting flights is an important piece of industrial equipment used to contact granular solids with a gas stream. Applications include the drying of materials such as wood chips, coal, grain, and metallurgical ores, the cooling of fertilizer pellets and more recently the combustion of coked oil sand. A new mathematical model for a rotating drum with lifting flights that predicts the residence time of particles is proposed. Particle motion is considered in both the airborne phase and the dense phase. Moreover, the holdup and the axial flow rate of particles in the two phases are determined separately. Overall, the model is more flexible than previous models. The drum may be inclined or horizontal with cocurrent or countercurrent flow, may have any type of lifting flights and may be underloaded or overloaded.

ISSN:0008-4034    

DOI:10.1002/cjce.5450710302

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

年代:1993

数据来源: WILEY

摘要:

AbstractEvaluations of apparent slip and polymer adsorption are reported for laminar capillary flow of dilute aqueous solutions of the three homologues WSR 301, Coagulant and FRA of Polyox. Measurements were carried out using glass tubes coated with a silane compound (dimethyldiethoxysilane) as well as for the untreated glass tubes. The results indicate that flow enhancement is dominant at the very low polymer concentrations and flow retardation is dominant at the higher concentrations comprising the polymer concentration range investigated. A transition from a positive to a negative effective velocity at the wall was observed with increasing polymer concentration.A new analysis was applied to separate the contributions of polymer adsorption and slip in the evaluation of the effective velocity at the wall. Effective hydrodynamic thicknesses of the adsorbed polymer layers are presented as a function of the polymer molar mass and concentration and the wall shear stress. The thickness of the adsorbed layer at zero shear was also evaluated from the capillary flow data.

ISSN:0008-4034    

DOI:10.1002/cjce.5450710303

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper deals with the use of a two‐fluid model for predicting the thermal‐hydraulic characteristics of the rewetting and refilling of hot horizontal tubes. The two‐fluid model equations were simplified and solved using an explicit finite difference scheme. A set of constitutive equations is used for closure. A new film boiling model and a model for evaluating the rate of latent to total heat in film boiling were incorporated in the two‐fluid model. A newly proposed rewetting criterion, based on vapour film collapse, was used to mark the end of the film boiling regime. The model is capable of predicting the rewetting and refilling process in horizontal tubes under conditions of stratified or inverted annular refilling flow. The model predictions were found to be in good agreement with the experimental

ISSN:0008-4034    

DOI:10.1002/cjce.5450710304

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

年代:1993

数据来源: WILEY

摘要:

AbstractMass transfer of benzoic acid from drops dispersed into a continuous phase of mineral oil with high viscosity has been investigated both with and without an imposed non‐uniform d.c. electric field. Total mass transfer efficiency was significantly enhanced in the presence of the high voltage electric field. The results indicate that the application of the electric field to the drop formation process does not change the fundamental mass transfer mechanisms and the mass transfer during drop free fall can also be described by existing mass transfer models. The results also suggest that the high viscosity of the continuous phase inhibits the drops oscillation as well as circulation when the drop sizes become smaller under the applied high voltage electric field. Therefore the significant enhancement of mass transfer efficiency in the present work is mainly due to the increased specific interfacial are

ISSN:0008-4034    

DOI:10.1002/cjce.5450710305

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

年代:1993

数据来源: WILEY

摘要:

AbstractExperiments were carried out using nanofiltration to separate salts from a hydrogen sulphide scrubber solution taken from an iron‐based liquid‐redox process. The scrubber solution used in these experiments contained organic chelating agents, iron, and various alkali metal inorganic salts (i.e., sulphates, thiosulphates, carbonates, and bicarbonates). The nanofiltration unit was equipped with monovalent ion‐selective membranes.Results indicated that the nanofiltration membranes retained organic materials and iron and allowed ionic species (e.g., SO42‐, S23‐, CO32‐, HCO3‐) to permeate. Results also indicated that the nanofiltration membranes used in these experiments preferentially removed CO32‐and HCO3‐over SO42‐and S2O32‐. The nanofiltration tests did not show any sign of membrane degradation in terms of ion selectivity; however, at high total‐dissolved solids concentrations, the permeat

ISSN:0008-4034    

DOI:10.1002/cjce.5450710306

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe upgrading of bio‐oil, obtained by fast pyrolysis of maple wood, was studied over HZSM‐5 in a fixed bed micro‐reactor operated at atmospheric pressure and in the temperature range 330‐425°C. The objective of upgrading was to maximize the amount of organic distillate product with a high yield of aromatic hydrocarbons. A maximum organic distillate of 38 wt.% of bio‐oil, which represented 28.6 wt.% of wood, was obtained at 370°C. The yield of aromatic hydrocarbons was 19.9 wt.% of wood. Above 400°C, nearly 50 wt.% of the bio‐oil was converted to coke and char. The conversion of non‐volatile components of the bio‐oil (pitch) to volatiles was at a maximum of 68 wt. % at 370°C. However, when the bio‐oil was co‐processed with tetralin, the maximum conversion of non‐volatiles increased to 86 wt.% at 410°C and the amounts of coke and char decreased. The yield of aromatic hydrocarbons also decreased to a maximum of 10.3 wt. % of wood. The role of tetralin was mainly as a diluent and not a

ISSN:0008-4034    

DOI:10.1002/cjce.5450710307

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe reaction rates for the hydrolysis of COS on both alumina (Kaiser 201) and titania (CRS 31) were measured from 270 to 330°C using a laboratory Berty reactor over ranges of water concentration, 2‐12 mol %, and COS concentrations, 0.5‐2 mol %. Four mechanism‐related model functions were tested in the search for the best fitting function by using nonlinear regression techniques. The results indicate that an Eley‐Rideal model provides the best fitting rate function for the hydrolysis of COS for both alumina and titania, even though their catalytic activities are different. The Bates and Watt's (1980) curvature measure along with simulation studies were used in the nonlinear regression search for the best values of the model parameters. The kinetic parameters obtained confirm that CRS 31 appears to be the better of the two catalysts for COS hydrolysis. The adsorption of water vapor significantly retards the hydrolysis rate, more so for Ka

ISSN:0008-4034    

DOI:10.1002/cjce.5450710308

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe capture of sulphur via the H2S‐CaO reaction during gasification of delayed coke has been investigated in a 6.4 cm dia. semi‐batch stirred bed reactor. Calcines from one of three limestones or a dolomite were mixed with coke which was then gasified in a steam‐nitrogen mixture at atmospheric pressure and 930°C. The H2S content of the gas, and the sulphur content of the sorbent were determined as functions of time. The effects of sorbent surface area, percentage calcination, and the Ca/S ratio on the extent of sulphur capture and the conversion of sorbents were determined. The sulphidation reaction was analyzed using continuous and grain models. After an initial stage of chemical control the reaction appears to be controlled by diffusion through the product layer of the

ISSN:0008-4034    

DOI:10.1002/cjce.5450710309

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe bulk polymerization ofn‐butylmethacrylate was investigated in a counter‐rotating twin screw extruder. It appeared that the gel effect, occurring with bulk polymerizations, affected the polymerization progress very strongly. Due to this effect the conversion of the reaction is independent of the rotation speed of the screws. The reactive extrusion diagram, presented in this paper, indicates how the different phenomena interact with each other and helps to understand the influences of extruder parameters and reaction parameters on the proc

ISSN:0008-4034    

DOI:10.1002/cjce.5450710310

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn this work, the traditional external loop, airlift bioreactor has been fitted with a spinning sparger. Baffles were located beyond the sparger circumference to prevent vortex motion throughout the bioreactor. The flat plate, spinning sparger had six orifices and was located below the downcomer connection to prevent the generation of a high shear environment inside the bulk medium as would be found in a stirred tank bioreactor. The spinning motion of the sparger produces smaller diameter bubbles with higher gas hold‐ups and interfacial areas inside the bioreactor. Data and empirical correlations are presented for these features as well as liquid circulation velocity and mixing characteristics as functions of the spinning rate, superficial gas velocity and type of mediu

ISSN:0008-4034    

DOI:10.1002/cjce.5450710311

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

年代:1993

数据来源: WILEY