摘要:

AbstractA non‐invasive γ‐ray emission system, employing eight NaI detectors, has been developed to follow the motion of a single radioactive particle in a three‐dimensional spouted bed reactor. The count‐rates measured simultaneously by the detectors are converted into tracer coordinates (x, y, z) using a pre‐established calibration model which accounts for every physical and geometrical aspects involved in the spouting facility. Typically four hundred thousands successive coordinates, obtained over 3.5 hours of particle tracking, are used for determining the average particle velocity field and other hydrodynamic quantities such as the cycle time distribution, the spout shape and the solid exchange distribution at the spout boundary, which could not be evaluated accurately using any available

ISSN:0008-4034    

DOI:10.1002/cjce.5450720602

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

年代:1994

数据来源: WILEY

摘要:

AbstractA computational procedure is employed in the present work to predict the flow field in a hydrocyclone. Computations are carried out for turbulent flow under assumptions of axial symmetry. Turbulence closure has been affected with the help of the conventionalk→ ϵ model that includes a new formulation of the turbulence dissipation equation. The existing formulation of the dissipation equation proved to be inadequate in predicting the true nature of the present flow field. Results of the procedure are discussed. The new model appears to predict correctly the behaviour of a conventional water‐fed hydrocyclone in the absence of an air

ISSN:0008-4034    

DOI:10.1002/cjce.5450720603

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

年代:1994

数据来源: WILEY

摘要:

AbstractConnaissant le débit initial d'un film mince de liquide tombant sur un ou plusieurs tubes horizontaux, on propose un modèle de calcul permettant la détermination des coefficients de transfert de chaleur locaux. Ce travail est effectué pour des nombres de Reynolds inférieurs à 2000 et pour un flux ou une température constant. Le modèle prend en compte non seulement les effets convectifs mais aussi la courbure de l'interface liquide‐vapeur. On évalue globalement la partie du film évaporée après son passage sur la surface d'échange. Les résultats de ce modèle montrent que dans le cas où le flux de chaleur pariétal est imposé, ce dernier n'a pas d'influence sur la valeur du coefficient d'échange. La prise en compte de la courbure de l'interface permet un meilleur accord avec l'expérience, en particulier en ce qui concerne l'évaluation du nombre de Nusselt moyen quand le nombre de Reynold

ISSN:0008-4034    

DOI:10.1002/cjce.5450720604

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

年代:1994

数据来源: WILEY

摘要:

AbstractHeat transfer has been investigated for several Newtonian and non‐Newtonian liquids mixed in a flat bottomed vessel equipped with a screw agitator and a coil acting simultaneously as draft tube and heat exchanger. Heat transfer rates from coil to liquid were determined for different coil designs, rheological properties and operating conditions in the heating and cooling modes. A circulation Reynolds number is defined, the characteristic length being the effective height of the heat exchanger (the coil) and the characteristic velocity being the circulation velocity of the fluid which was determined experimentally. Using this Reynolds number, it was possible to establish a single correlation for the Nusselt number as a function of Reynolds and Prandtl numbers. Geometric ratios do not appear in this correlation which could adequately represent more than 200 experimental data. A similar single correlation could not be obtained when using the conventional mixing Reynolds number. This novel system is shown to be very efficient for handling rheologically complex fluid

ISSN:0008-4034    

DOI:10.1002/cjce.5450720605

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

年代:1994

数据来源: WILEY

摘要:

AbstractA model is examined in order to predict the behaviour of a granular bed made with conductive particles subjected to an inductive electromagnetic field. The model shows how heat generated in the bed can be described by its electric impedance for the high‐frequency generator required for inductive heating. Once the relationship between electrical characteristics and power dissipation has been established, comparisons between experimental and theoretical results are presented and the validity of the model is discusse

ISSN:0008-4034    

DOI:10.1002/cjce.5450720606

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

年代:1994

数据来源: WILEY

摘要:

AbstractExperimental results are presented for the separation of monoclonal IgM antibodies from hybridoma cell cultures using tangential flow ultrafiltration with total recycle of the retentate. IgM antibodies are pentameric immunoglobulin molecules with a molar mass of 900 kDa and a tip‐to‐tip distance of 38 nm. The major impurity (foulant) in the supernatant sample was albumin, whose molar mass and diameter are 67 kDa and 7 nm, respectively. The antibody (product) recovery rate, variations in the permeation velocity and the time for a 90%‐reduction in feed volume were investigated using 100 and 300 kDa NMWCO membranes at three transmembrane pressures and two tangential velocities. A model is also presented, in which the ultrafiltration process is divided into two regimes: the surface fouling regime (characterized by the adsorption of antibody molecules on the membrane surface) and the internal fouling regime (characterized by pore‐blockage due to deposition of foulant protein molecules). Approximately 16% of the effective membrane area was blocked in the surface fouling regime. The model predictions are in satisfactory agreement with the experimental

ISSN:0008-4034    

DOI:10.1002/cjce.5450720607

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

年代:1994

数据来源: WILEY

摘要:

AbstractThree ultrafiltration membranes in series with molar mass cutoffs of 130,000, 15,000, and 5,000 Da, respectively were used to pretreat Kraft pulp bleach plant effluent prior to biological treatment. TheTOC(total organic carbon),COD(chemical oxygen demand) andAOX(adsorbable organic halogen) reductions for the permeate were 65, 70 and 85%, respectively with no significant change of toxicity. Treatment of the ultrafiltration permeate using tighter ultrafiltration (UF) and nanofiltration (NF) membranes with molar mass cutoffs less than 1,500 Da, yieldedTOCandAOXreductions of 90 and 99%, respectively with a permeate Microtox EC50level of 100%.

ISSN:0008-4034    

DOI:10.1002/cjce.5450720608

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

年代:1994

数据来源: WILEY

摘要:

AbstractA mechanistic mathematical model for the chemical absorption of mercaptan in sodium hypochlorite solution has been derived. In order to describe the process adequately, a semi‐verified complex scheme of the involved kinetic reactions based on stopped‐flow measurements with UV‐detection has been implemented. The overall system of differential equations has been solved numerically. For some asymptotic cases, approximation formulae are given. The process has been carried out in an aerosol operated jet loop reactor which is characterized by high interfacial areas at low liquid flow rates. Fitting the model solution to the experimentally obtained conversion data enabled determination of the unknown hydrodynamic parameters. By means of a sensitivity analysis, the influences of the different parameters are disc

ISSN:0008-4034    

DOI:10.1002/cjce.5450720609

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe electrocoagulation of kaolinite and bentonite suspensions was studied in a pilot electrocoagulation system at the Western Research Center of CANMET to assess the operating cost and efficiency of the process. Factors affecting the operating cost such as, the formation of passivation layers on electrode plates, flow velocity and concentration of sodium chloride in the suspension were examined. The operating costs investigated in this paper were the power cost of the electrocoagulation cell and the material cost due to the consumption of the aluminum electrode. Comparison was based on the settling properties of the treated product: turbidity, settling rate, and cake height. Higher concentration of sodium chloride resulted in greater amount of aluminum dissolved chemically and electrochemically into the suspension and thus a better clarity of the supernatant of the treated product. Increased flow velocity could reduce significantly the operating cost while improving both clarity of the supernatant and the compactness of the sludge volume. The passivation layers developed quickly with time during the electrocoagulation process and more energy became wasted on the layers.

ISSN:0008-4034    

DOI:10.1002/cjce.5450720610

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

年代:1994

数据来源: WILEY

摘要:

AbstractBioconversion of sludge from the primary clarifier of a sulphite pulping operation to ethanol offers a number of advantages over conventional disposal options. The amount of material which must be disposed of is reduced while, at the same time, salable and environmentally friendly fuel‐ethanol is produced. In this study, primary clarifier sludge (PCS) was shown to be hydrolysed to produce fermentable sugars at a rate proportional to enzyme loading. Initial (1 hour) hydrolysis rates as high as 12.6 g reducing sugar/L · h were observed at an initial enzyme loading of 10 filter paper units (FPU)/g. Hydrolysis was inhibited by spent sulphite liquor (SSL), an inhibition which could be completely overcome by fermenting the SSL to remove sugars. Surfactants were found to only marginally improve the production of sugars. To reduce the deleterious effects of end product inhibition, single stage simultaneous hydrolysis and fermentation (SHF) was carried out using cellulase enzymes andSaccharomyces cerevisi

ISSN:0008-4034    

DOI:10.1002/cjce.5450720611

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

年代:1994

数据来源: WILEY