摘要:

AbstractRecent progress in understanding crystallization processes is reviewed, especially with regard to the problem of crystal‐size distribution (CSD) and its many interactions with the design, analysis, and operation of crystalizers. This subject is considered from both the researcher's and practitioner's points of view, and special attention is given to the impact of recent theories on crystallizer design and operation.A generalized theory for the analysis and prediction of CSD, based on population balance mechanics, has been developed and tested over the past decade. Predictive design of CSD is now a possibility with the design techniques presented here and using suitable bench‐scale data. Published evaluations of the reliability of design methods utilized in commercial practice would be a valuable asset to the science of crystallizat

ISSN:0001-1541    

DOI:10.1002/aic.690190603

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractFive different fine powders with average particle size of about 100 microns or smaller were fluidized with air over their respective bubblefree ranges of fluidization. Photographs taken through the front transparent wall of the column showed that the beds contained cavities and microchannels whose sizes were of the same order of magnitude as the particle size. It is shown that interparticle van der Waals adn capillary forces play an important role in the bubble‐free expansion of small particles. Measurements of bed expansion and average particle drag coefficients are consistent with the proposed role of interparticle force

ISSN:0001-1541    

DOI:10.1002/aic.690190604

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractA liquid thermistor consisting of a salt‐triethylamine‐water solution shows a resistance increase of 100% per degree centigrade over a range of 8°C. Outside this specific temperature range, the resistance changes slowly. The altered resistance results from the phase change at the critical solution temperature. While devices of this type can show major hysteresis and are restricted to specific temperatures, their response is faster than a millise

ISSN:0001-1541    

DOI:10.1002/aic.690190605

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractIn reacting systems, the number of independent chemical reactions, the number of components, and the number of chemical chemical species are generally assumed to be so related that the sum of the first two equals the third. Standard methods of obtaining the number of independent reactions (that is, formation equations or rank of the element‐by‐species matrix) may fail when chemical isomers appear in reactant streams, product streams, or both. The errors encountered with various types of isomers are delineated in this paper along with corrective measures. The element‐by‐species matrix is judged to be more suitable as a starting point than formation equations when matrix size and number of manipulations are con

ISSN:0001-1541    

DOI:10.1002/aic.690190606

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractThe time on stream theory of catalyst decay is applied to gas oil cracking selectivity data from a static bed reactor operating with a diffusion limited catalyst. It is found that intraparticle diffusion affects the reactions leading to the disappearance of gas oil to a much greater extent than the reaction leading to the recracking of gasoline and catalyst poisoning. Reasons for this behavior are postulated. It is also found that the overall kinetic order for the rate of disappearance of gas oil is decreased with the result that maximum selectivity occurs at a higher conversion value than for a corresponding diffusion‐free catalyst. It is concluded that probably diffusion limitation is not a serious problem with respect to gasoline selectivity in commercial reactor

ISSN:0001-1541    

DOI:10.1002/aic.690190607

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractThe rate of the Diels‐Alder reaction of isoprene with maleic anhydride has been measured in the vicinity of the upper critical solution points of two liquid‐liquid mixtures, and the rate of the Menschutkin reaction of ethyl iodide and triethylamine has been investigated near a lower critical solution point. Anomalous behavior has been observed, with the former reaction rate augmented by up to 40% and the latter apparently running 25–30% too slow. A possible explanation for these results is presented in terms of transition state theory and the abrupt behavior of the solution activities of dilute solutes near a critical

ISSN:0001-1541    

DOI:10.1002/aic.690190608

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractThe gas chromatographic (GC) method for thermodynamic measurements of polymer‐solvent systems at finite concentration has been improved to extend its operating range from atmospheric pressure to over 70 atm and over 240°C. This paper describes the design and opertion of the equipment and the mathematical treatment of the GC data, and presents experimental results forn‐hexane and isooctane in high density polyethylene. These results include the solubility isotherms, activity coefficients, and polymer‐solvent interaction parameters. The activity coefficients covering a range from 4 to 70 atm forn‐hexane in the polymer solution were correlated successfully as a function of composition using a two‐parameter segment interactio

ISSN:0001-1541    

DOI:10.1002/aic.690190609

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractThe stability of crystal‐size distribution (CSD) in the classified product crystallizer with fines removal was investigated using spectral techniques to determine stable solutions of the linearized population balance. The model used to describe the crystallizer assumed rapid growth kinetics (high yield), magma‐dependent secondary nucleation, and recycle of dissolved fines. Fines removal and classified product removal were characterized in the model by piece‐wise constant removal rates (R– 1) andztimes the MSMPR removal rate, respectively.Stability regions were presented as critical values of the kinetic nucleation/growth rate exponenti=d(logB°)/d(logG) versus dimensionless parameters of the system. The parameters which influence CSD stability were maximum fines size and removal rate, product classification size and removal rate, and the magama‐characterizing exponent in the nucleation expression. Whether or not dissolved fines are recycled directly back to the crystal magma also influences

ISSN:0001-1541    

DOI:10.1002/aic.690190610

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractData are obtained and a model derived for describing particle size distribution for molten metals atomized by two water jets. The influences of water jet parameters on size distribution and median size are reported and discussed in terms of fundamental quantities and model predictions. The data, which were obtained using fan‐spray jets impinging at an apex angle of 60° to atomize Type 4620 steel, indicated that median size was primarly a function of water jet veloci

ISSN:0001-1541    

DOI:10.1002/aic.690190611

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY

摘要:

AbstractThe steady laminar boundary layer flow past two‐dimensional surfaces of a power‐law non‐Newtonian electrically conducting fluid in a transverse external magnetic field is studied. The Crocco boundary layer equation is presented and, for the flow over a flat plate, solved approximately by the use of the integral method. Three examples are studied in detail. The transverse magnetic field has a greater influence on the flow of a dilatant fluid than for a pseudo plastic fluid. Increasing the magnetic field strength increases the shear stress coeffi

ISSN:0001-1541    

DOI:10.1002/aic.690190612

出版商:American Institute of Chemical Engineers    

年代:1973

数据来源: WILEY