摘要:

AbstractModels of the role of the interstitial fluid for dispersion in a fixed bed for very high Reynolds numbers are examined in detail to determine how well they fit the physical requirements of finite speed of signal propagation, no backmixing, conservation and correct asymptotic form. It is concluded that no linear continuous partial differential equation of finite order can satisfy all of these requirements as well as the cell model, although all models for sufficiently large axial space and time variables are very good approximations to the cell model. Some new hyperbolic models are presented and their solutions obtained and compared with the standard solutions. In present day design it appears that no model has an outstanding advantage over any other.

ISSN:0001-1541    

DOI:10.1002/aic.690260402

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractThe phenomenon of unsteady heat transfer from a spherical droplet or solid particle moving slowly in a different fluid is analyzed, for the case in which the thermal resistances of the dispersed and continuous phases are comparable. The effect of the Peclet number (over the range 0 ⩽Pe⩽ 1,000) and of the internal circulation of the droplet on the development of temperature fields is investigated. The energy equations for the interior and exterior of the droplet are solved by the finite‐difference method of alternating directions. The results are compared with a number of previously published approximate m

ISSN:0001-1541    

DOI:10.1002/aic.690260403

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractHeat transfer from a vertical tube in fluidized beds was investigated by measurement of emulsion packet residence times. The root‐square‐mean residence times were then used in a modified packet model to successfully predict effective heat transfer coefficie

ISSN:0001-1541    

DOI:10.1002/aic.690260404

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractIn slurry transport, the critical velocity is defined as the minimum velocity demarcating flows in which the solids form a bed at the bottom of the pipe (bed load flows) from fully suspended flow. An analysis based on balancing the energy required to suspend the particles with that derived from dissipation of an appropriate fraction of the turbulent eddies is used to develop a correlation for prediction of the critical velocity. Comparison of the results with available experimental critical velocity data, relating to a rather wide variety of slurry systems, confirms that the present correlation does a superior job of prediction than all previously proposed critical velocity correlations.

ISSN:0001-1541    

DOI:10.1002/aic.690260405

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractThe continuous membrane column provides a revolutionary separation technique. Both the most and the least permeable components can be separated continuously to any degree without cascading. Experimental data for several binary systems show good agreement with theory.

ISSN:0001-1541    

DOI:10.1002/aic.690260406

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper extends previous modeling calculations of concentration profiles and reaction rates in tubular flow reactors by including very fast wall reactions such as surface catalyzed atom recombinations. The plug flow assumption is investigated and found to be valid in tubular flow reactors when the dimensionless wall reaction rate is less than on (H1). If these criteria are not met, this work provides a correlation yielding a correction factor which can be applied to the mean residence time. The method is applied to experimental data relating to the deactivation probability of two types of atoms on teflon and quartz. Values of 1.0 + 0.2 × 10−4and 1.7 + 0.4 × 10−4for the deactivation probabilities of 0 and N atoms, respectively, are re

ISSN:0001-1541    

DOI:10.1002/aic.690260407

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractPorous particles are described by a random capillary model predicting the frequency of pore intersections and the evolution of pore volume and surface area during reaction. The model is applied to char gasification at chemically controlled rates, and the results are compared with data from the literature.

ISSN:0001-1541    

DOI:10.1002/aic.690260408

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractThe simultaneous solution of all the equations for a general system of interlinked, multistaged separators is considered. The interlinks may be simple streams or reciprocal streams, and a particular separator may have bypassing streams (for example, pumparounds). Algorithms are developed that automatically arrange the linearized equations so that for a Newton‐Raphson type of solution procedure using, for example, the Naphtali‐Sandholm technique, a minimum or nearly minimum number of nonzero blocks occur outside the tridiagonal band so that computational memory and time requirements are minimized. The nonzero and nonidentity blocks are stored in a single vector of variable dimens

ISSN:0001-1541    

DOI:10.1002/aic.690260409

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractExpressions are derived for the steady state flux of sulfur dioxide through films of water and neutral and alkaline salt solutions. A local equilibrium approximation yields and analytical expression for the flux through water and neutral salt solutions. To account for deviations from local equilibrium, the conversion from sulfur dixoxide (aq) to sulfur containing ions (and vice versa) is assumed frozen near the boundaries of the film (x= 0,x= 1). The thickness of the boundary layer nearx= 1 ispH dependent, indicating an increasing deviation from equilibrium flux in increasingly alkaline solutions. Strong nonequilibrium behavior can be realized under some conditions for a film of concentrated sodium hydroxide operating as a liquid membrane and in conventional scrubbers.

ISSN:0001-1541    

DOI:10.1002/aic.690260410

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY

摘要:

AbstractMeasurements were made of the steady state flux of sulfur dioxide through films of water and solutions of neutral and alkaline sodium salts (0.1 to 2.0 M sodium chloride, 10−3to 3.0M sodium hydroxide, NaHSO3or sodium sulfite) with sulfur dioxide partial pressures between 10 and 100Pa. In agreement with equilibrium theory (Part I), data from water and sodium chloride solutions show that HSO 3−is responsible for 83 to 95% of the flux (facilitation factor F between 5 and 19). In alkaline solutions, HSO 3−and other sulfur containing species cause F to be as large as 1 370. Equilibrium theory, however, overpredicts F by up to a factor of 7. The NEBLA (Part I) accounts for this

ISSN:0001-1541    

DOI:10.1002/aic.690260411

出版商:American Institute of Chemical Engineers    

年代:1980

数据来源: WILEY