摘要:

AbstractThe critical impeller speed for solid suspension in gas‐liquid‐solid systems has been measured in multi‐impeller agitated contractors of 0.15 and 0.30 m and ID and 1.0 m height. Three types of impellers, i.e. disk turbine (DT), pitched turbine downflow (PTD) and pitched turbine upflow (PTU) were used. Air, deionised water and sand particles were used as the gas, liquid and solid phases, respectively. The superficial gas velocity and solid loading were varied in the ranges 0–15 mm/s and 0.5 to 10% w/w, respectively. The effects of impeller type and its diameter, particle size and loading and gas flow rate were studied. Some measurements of gas hold‐up and mixing time were also made in order to get some insight of the hydrodynamic behaviour of the reactor. The critical impeller speed for solid suspension in the presence of gas (nisg) was found to be more than that in the absence of the gas and the increase of critical speed correlated well with the gas flow rate. The influence of particle—liquid parameters on solid suspension speed in the gassed system was similar to but relatively weaker than that in the ungasse

ISSN:0008-4034    

DOI:10.1002/cjce.5450730302

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

年代:1995

数据来源: WILEY

摘要:

AbstractA momentum integral model is developed to predict the size and maximum recirculating mass flow rate for the central recirculation zone produced by a swirling flow in a sudden expansion as a function of expansion ratio, swirl intensity, and inlet velocity profile shape. Experimental measurements of velocity profiles in the recirculating flow are presented for three different expansion ratios and are used to validate the model. The model is shown to give good agreement with the measurements. The recirculation rate is found to increase roughly linearly with inlet swirl intensity and expansion size.

ISSN:0008-4034    

DOI:10.1002/cjce.5450730303

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

年代:1995

数据来源: WILEY

摘要:

AbstractThree regimes of air‐core vortex formation are demonstrated to exist for the free draining of liquids containing angular momentum. These comprise of a rapidly intensifying air‐core vortex, a quasisteady vortex and a decaying vortex. The regimes are shown to be strongly influenced by the size of the drain‐port used in relation to the tank diameter. The influence of Froude number on air‐core vortex is di

ISSN:0008-4034    

DOI:10.1002/cjce.5450730304

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

年代:1995

数据来源: WILEY

摘要:

AbstractLe présent article a pour objet l'étude expérimentale du dépǒt de particules projetées par un jet gazeux sur une surface plane horizontale. La répartition granulométrique locale des particules déposées est analysée par une technique d'analyse d'images. Les mesures sont effectuées avec différents lots de particules et sous diverses conditions expérimentales. Les valeurs des distances d'arrět sont regroupées dans une représentation adimensionelle en fonction d'un nombre de StokesSt0défini en sortie de buse. La finesse de la séparation granulométrique observée dans le dépǒt est enfin évaluée en fonction d'un p

ISSN:0008-4034    

DOI:10.1002/cjce.5450730305

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe two‐dimensional spouted bed has been pointed out in recent research works as an improved configuration of spouted beds. The main advantages in relation to the conventional spouted beds are the easy construction and scale‐up. In this work we begin the study of coating of tablets in two‐dimensional spouted beds. An experimental system was constructed and the data obtained were used to determine the values of maximum pressure drop, minimum spout flowrate and gas‐to‐particle heat transfer coefficient, for 36 process conditions. The experimental results have been correlated with process and geometrical p

ISSN:0008-4034    

DOI:10.1002/cjce.5450730306

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

年代:1995

数据来源: WILEY

摘要:

AbstractMass transfer coefficients between particles and liquids in a slurry bubble column and a three‐phase fluidized bed containing small size particles were obtained with two mass transfer systems: (1) K+–Na+ion‐exchange in cation‐exchange resin bead beds, including anion‐exchange resin beads as inert particles; (2) zinc dissolution by HCl in zinc‐plated glass bead beds, and in beds of non‐plated glass beads. Operating parameters were gas velocity, liquid velocity, particle diameter, and particle concentration. The dependence of mass transfer coefficients on these parameters is discussed from the viewpoint of the energy supplied into the systems. Correlations of the experimental data using dimensionless groups are compared to previous

ISSN:0008-4034    

DOI:10.1002/cjce.5450730307

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

年代:1995

数据来源: WILEY

摘要:

AbstractUsing a portion of the product N2to purge the permeate side of a membrane module in order to reduce the membrane area for the separation of air for nitrogen production is considered. A simulation program was developed and used to compare a purge system to a conventional non‐purge permeator. Both the selectivity of the membrane and the feed/permeate pressure ratio were found to affect the ability of the purge stream to reduce the membrane area. The purge stream reduces the recovery of nitrogen, which results in a minimum in the membrane area per unit of product flo

ISSN:0008-4034    

DOI:10.1002/cjce.5450730308

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe methane oxidative coupling performance of a fixed‐bed reactor was successfully translated to a bubbling fluidised‐bed reactor and this reaction mode was superior to spouted‐bed, inclined and mechanically‐agitated fluidised‐bed units. Also, a two‐stage bubbling fluidised‐bed reactor with inter‐stage addition of oxygen had the same performance as the single‐stage unit, for the same total oxygen input, over a wide range of operating conditions. Overall the bubbling fluidised‐bed is preferred, catalytic reactions dominate over non‐catalytic gas phase reactions in determining the reactor performance, the gas phase exhibited plug‐flow behaviour and the performance was independent of the gas phase oxygen partial pressure for a given oxygen input. The best hydrocarbon yield achieved

ISSN:0008-4034    

DOI:10.1002/cjce.5450730309

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

年代:1995

数据来源: WILEY

摘要:

AbstractModified Ni catalysts supported on alumina and reduced in CH4have been investigated for the synthesis of C4hydrocarbons from CH4and C3H6. Addition of K or P to the Ni/Al2O3catalyst increased C4selectivity and C3H6conversion. A maximum selectivity to the desired C4product of 9 mol % was obtained at 350°C and 101 kPa with a feed gas composition of 90 mol% CH4/10 mol% C3H6, but the catalyst activity declined rapidly with time‐on‐stream. Large amounts of unreactive carbon were deposited on the catalyst surface following reduction in CH4and reaction in CH4/C3H6. However, the relative amount of a much more reactive species identified from Temperature‐Programmed‐Surface‐Reaction that was formed in the presence of CH4and C3H6, is shown to correlate with the catalyst C4yield. Both the C4yield and the relative amount of this low temperature carbonaceous species increased in the order Ni

ISSN:0008-4034    

DOI:10.1002/cjce.5450730310

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

年代:1995

数据来源: WILEY

摘要:

AbstractSelective non‐catalytic reduction of nitric oxide (NO) using ammonia was studied with up to 15% (by volume) oxygen at 102 kPa. The experiments were conducted in an electrically heated laminar‐flow, quartz reactor using mixtures of N2, O2, NO, and CO to simulate exhaust gas. The base case condition included 330 ppmv of NO, 495 ppmv of NH3, and 15% O2. At a reactor temperature of 1050 K, 77% of the NO was removed. For a lower oxygen concentration of 1%, the NO removal was as high as 98% at 1100 K. The degraded performance at high oxygen concentrations is attributed to increases in the oxidation reactions.A major result of this work was the quantification of the amount of N2O in the treated gases. For the base case conditions, 21 ppmv of N2O was measured for a reactor temperature of 1075 K. Increasing the ratio of NH3to NO (by increasing the NH3concentration) increased the maximum NO removal and decreased the temperature at which this level of NO removal was achieved. For the higher NH3concentrations, however, the N2O concentration increased to as high as 54 ppmv. The oxidation products of ammonia (in the absence of NO) for these conditions were found to include first N2O beginning at 900 K and then NO beginning at 1050 K. Comparisons between these experimental results and predictions from the Miller and Bowman (1989) model indicate that further enhancements of the model may be necessary to incorporate the features of high oxygen conditi

ISSN:0008-4034    

DOI:10.1002/cjce.5450730311

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

年代:1995

数据来源: WILEY