摘要:

AbstractA flash‐evaporation technique is used to obtain vapor deposition characteristics for the binary alkali sulfates K2SO4+ Na2SO4at 1 atm above 1, 100 K. This technique gives results of immediate engineering interest, such as dewpoint temperatures, condensate composition and rates of vapor deposition as well as useful data on the system's thermodynamic characteristics. It is concluded that alkali sulfate deposition and vaporization in combustion environments are inevitably influenced by chemical reactions such as hydroxide formation. It is also concluded that solution nonideality is important even for homologous alkali‐salt mixtures.Predictions are made using convective‐diffusion mass transfer theory, accounting for chemical reactions by means of effective volatilities, and assuming regular, nonideal condensate solutions. The predicted dewpoints, condensate compositions and deposition rates are quantitatively consistent with experimental observations. This approach, validated here, can be extended to more extreme conditions of engineering interest, including turbulent, high‐temperature/pressure

ISSN:0001-1541    

DOI:10.1002/aic.690331202

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe role of inter‐ and intraparticle transport resistances in the sensitivity behavior of a fixed‐bed catalytic reactor is fully elucidated. The parametric sensitivity regions obtained using a heterogeneous one‐dimensional plug flow model are reported for various values of the involved dimensionless parameters. Comparisons with previous sensitivity criteria and with experimental data are also pres

ISSN:0001-1541    

DOI:10.1002/aic.690331203

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractNew data and analyses are presented for describing gas and solids behavior in a slurry bubble column. Axial solids concentration and bubble size distributions were measured in a 0.108 m ID slurry bubble column apparatus operated at steady state conditions. The column was operated with and without internal baffles. The slurry and gas superficial velocities ranged from 0.0077 to 0.009 m/s and from 0.031 to 0.24 m/s, respectively. The solid phase consisted of glass spheres in a narrow size range with a mean diameter of 96.5 μm; the liquid phase consisted of tap water.With a one‐dimensional sedimentation‐dispersion model, the data have been used to predict average solids loadings and axial distributions of the solids for specified operating conditions. Local bubble size and concentration measurements indicate that the slurry bubble column was operated in the churn‐turbulent flow regime throughout the entire range of operating conditions used in this study. The impact of internal baffles and solids concentration on the gas and solids behavior is dis

ISSN:0001-1541    

DOI:10.1002/aic.690331204

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThe oxidation of CO over aluminum‐supported Ag was studied at 147°C using transient experiments. Long‐time‐scale dynamics were observed that could not be explained by previously postulated kinetic mechanisms for this reaction system. A model is presented with kinetic parameters estimated from steady state and transient data that is able to reproduce a variety of cycled feed stream experiments. The model incorporates a slow reversible step which forms an adsorbed oxygen species that blocks reaction

ISSN:0001-1541    

DOI:10.1002/aic.690331205

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractA finite‐element method is given for efficient simulation of multiphase distillation systems. Breakpoints are adaptively located to coincide with phase discontinuities. Thermodynamic criteria for the states at these discontinuities are included in the equation system. The adjustable breakpoint locations are calculated simultaneously with the other system variables by global Newton iteration. Worked examples demonstrate the accuracy and efficiency of the metho

ISSN:0001-1541    

DOI:10.1002/aic.690331206

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractFuzzy set theory is used to describe similarity of chemical engineering systems. The development of system similarity is given, and methods of determining a similarity relation are discussed. The system similarity relation is applied to the problems of measuring correlation confidence and quantifying modeling error. Sample problems are examined.

ISSN:0001-1541    

DOI:10.1002/aic.690331207

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractDiffusion and chemical reaction in a catalyst pore is simulated as a Monte Carlo process. In this analysis the average diffusion distance, calculated for a large number of wall collisions, and the reaction probability are computed as two independent statistical events. This formulation yields results that compare very well with the theoretical values, yet uses minimal computer time. Results reported include typical concentration profiles and effectiveness factors for first‐ and second‐order isothermal reactions using the method described. These results show promise of extension to more complex systems where analytical solutions are not availa

ISSN:0001-1541    

DOI:10.1002/aic.690331208

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractIn turbulent flow the equations governing the development of conversion vs. distance are not closed because of the contribution of the concentration fluctuations to the average reaction rate. Toor's hypothesis permits closure from data obtained for mixing without reaction. This paper presents a critical review of the derivation of the hypothesis and discusses its validity.

ISSN:0001-1541    

DOI:10.1002/aic.690331209

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractA new, unobtrusive method for liquid‐liquid two‐phase flow data collection was proved to be reliable in this research. Drop size distributions and concentration profiles were determined for a dilute water‐inkerosene system under horizontal straight pipe flow using this technique, and the Segev model for predicting concentration profiles was tested with the data collected here.The drop size distributions were found to follow a Rosin‐Rammler function for a limited droplet diameter range, and the average value of the exponent in the Rosin‐Rammler equation was determined to be 2.0. The velocity where the flow regime makes a transition from stratified to adequately dispersed flow was found to be between 2.0 and 2.2 m/s. Concentration profiles predicted by the Segev model were in general agreement with the profiles determined in this work, and using the proper choice of model parameters noticeably improves the model pr

ISSN:0001-1541    

DOI:10.1002/aic.690331210

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractMass transfer rates in laminar and turbulent nonseparated boundary layers are asymptotically expanded for small values of the diffusivity

ISSN:0001-1541    

DOI:10.1002/aic.690331211

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY