摘要:

AbstractNew experimental data indicate that mass flux in cocurrent gas‐liquid flows may be determined by the use of Pitot tubes in conjunction with a local mixture density measurement technique. The data were taken over a wide range of flow regimes in a horizontal pipe and included separated patterns such as stratified and annular flows. Local mixture densities were obtained by a computer‐assisted algebraic reconstruction technique that used chordal average densities measured by traversing gamma beam attenuation.The results extend the applicability of this mass flux measurement technique well beyond the relatively homogeneous, high‐pressure, steam‐water flow situations originally studied by Banerjee and Nguyen

ISSN:0001-1541    

DOI:10.1002/aic.690270202

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractSome fluid mechanical information concerning mixing generation in complex flow fields can be obtained from conversion data of fast chemical reactions. Computation of such information and averages required in the procedure are presented here. Complex turbulent flow fields present deterministic‐like behavior when analyzed in average sense with regard to mixing generatio

ISSN:0001-1541    

DOI:10.1002/aic.690270203

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractDust particles originally generated by two steelmaking processes were dispersed in an air stream and passed through a pilot‐scale high gradient magnetic filter. In accordance with theoretical predictions, the experimental results showed that collection was improved by increasing the depth or density of the steel wool filter, increasing the applied magnetic field, or decreasing the filtration velocity. Collection efficiency increased with particle size up to about 2 μm, above which the efficiency tapered off, apparently due to reentrainment effects. Collection efficiencies of greater than 99% were obtained, indicating that high gradient magnetic filtration may be a practical method of controlling particulate emission from processes in the iron and steel indust

ISSN:0001-1541    

DOI:10.1002/aic.690270204

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractA new static cell for vapor‐liquid equilibria up to 100 MPa between 233 and 433 K is presented. A detachable sampling microcell and a special chromatographic injector are used in a new sampling system suitable for gas chromatographic analysis of mixtures with high boiling components. The test system is N2—n‐Heptane at 305

ISSN:0001-1541    

DOI:10.1002/aic.690270205

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractA viscous lamina of given mean thickness flows down a wavy incline. Assuming low Reynolds number and small perturbations due to the wavy striations, the velocity profiles and the free surface profile are determined. It is found that the amplitude and phase shift of the free surface depend, in a complicated manner, on the surface tension and the wave length and orientation of the wavy striations. The motion of a particle on the free surface experiences drift which is also a function of the surface tension, the amplitude, wave length and orientation of the wavy incline.

ISSN:0001-1541    

DOI:10.1002/aic.690270206

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractKinetics of thermal regeneration of powdered activated carbon containing adsorbed sucrose was studied from 298 to 1033 K. Most of the data were obtained (by measuring mass vs. time of spent carbon samples) in a thermal gravimetric apparatus. The regeneration process was interpreted in terms of a two‐step process: (1) low‐temperature decomposition to an adsorbed intermediate and gaseous products; and (2) a higher temperature decomposition of adsorbed intermediate into adsorbed residual carbon and gaseous products.Surface area measurements indicated that most of the original carbon surface, but not all, could be recovered by thermal (with inert gas) regeneration up to 773 K. If permanent loss in surface is to be avoided during continued, cyclical use of the carbon, reaction with an oxidizing gas would be required after thermal regenerat

ISSN:0001-1541    

DOI:10.1002/aic.690270207

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractThe kinetics of the reaction between steam and spent activated carbon (from sucrose deposition) was studied at 1003 to 1123 K and 1 atm pressure. At these conditions some virgin carbon, upon which the sucrose was originally adsorbed, was also gasified. Rates of oxidation were essentially the same for spent and virgin activated carbon.The kinetics data fit a Langmuir‐Hinshelwood equation, originally proposed for gasification of other types of carbon, with an activation energy of 2.3 × 105J/mol.Surface area and pore volume measurements indicated that the adsorption capacity of the original carbon could be completely restored by thermal regeneration followed by reaction with steam. However, some activated carbon is lost implying that there would be an optimum extent of steam gasification in a cyclical adsorption‐regeneration pro

ISSN:0001-1541    

DOI:10.1002/aic.690270208

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractThe effect of varying pore structures on the kinetics of fluid‐solid reactions is investigated through the random pore model developed in prior papers (Bhatia and Perlmutter, 1980, 1981). By considering several idealized pore‐size distributions it is shown that a solid having a uniform pore size is intrinsically less reactive than one possessing a pore‐size distribution. For solids with bimodal pore size distributions optimal structures are shown to exist for which the reactivity is a maximum.Numerical solutions were obtained to the model equations for various values of the parameters characterizing the pore structure, the diffusion, and the chemical kinetics. The results show that the conversion‐time behavior and the expected ultimate conversion can be very sensitive to variations in surface area and porosity for reactions accompanied by an increase in volume of the solid phase.These findings are in agreement with experimental literature on the SO2‐lime reaction (Ulerich et al., 1978; Borgwardt and Harvey, 1972; Potter, 1969; Falkenberry and Slack, 1968) and the model is shown to fit the data of Borgwardt (1970), and of Hartman and Coughlin (1974, 1976). It is seen that this reaction is diffusion controlled under the conditions of Hartman and Coughlin, in consonance with their own finding using the grain model, and a prior Pigford and Sliger (1973) interpretation. The temperature behavior of the diffusion coefficient in the product layer suggests the participation of an activated process, possibly a solid state diffu

ISSN:0001-1541    

DOI:10.1002/aic.690270209

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractA sudden reduction in the feed temperature to a packed‐bed reactor leads to a transient temperature rise, which is referred to as the wrong‐way behavior. A pseudo‐homogeneous plug‐flow model is used to analyze the structure of this transient behavior. The key parameters which determine the magnitude of this response are the dimensionless adiabatic temperature rise, activation energy, heat transfer capacity, coolant temperature, magnitude of temperature drop and length of the reactor. A simple expression is derived for predicing the maximum transient temperatu

ISSN:0001-1541    

DOI:10.1002/aic.690270210

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY

摘要:

AbstractThe prior random pore model for kinetically controlled fluid‐solid reaction (Bhatia and Perlmutter, 1980) is generalized to include transport effects arising from boundary layer, intraparticle, and product layer diffusion. Numerical solutions are presented for a variety of conditions. The results show that the rate and surface area maxima predicted in the kinetic regime are shifted to lower conversions as intraparticle or product layer diffusional resistances increase. In addition, with increasing temperature a decrease in the overall reaction surface is predicted, in agreement with experimental findings (Kawahata and Walker, 1962).For reactions accompanied by an increase in the volume of the solid phase, it is shown that incomplete conversion may be expected, the ultimate conversion decreasing with an increase in the intrapellet diffusional resistance. Optimal temperatures for such reactions are also identifie

ISSN:0001-1541    

DOI:10.1002/aic.690270211

出版商:American Institute of Chemical Engineers    

年代:1981

数据来源: WILEY