The nonisothermal effectiveness factor (E. F. ) for reaction with kinetics r = kcm/(1 + Kc)a can be improved by catalysts with nonuniform activity distribution. The optimal distribution function in one-dimensional model with which the E. F. can be maximized is a δ-function which means that the activity of the catalyst should be concentrated on a layer with negligible thickness at a precise location x from the center of pellets. The general equations for predicting the value of x and the maximum E. F. as a function of thermodynamic, kinetic and transport parameters are derived and they can be given explicitly in the case of a = 0, m=a or isothermal reaction. For reactions with positive order kinetics the optimal position of the activity locates on the surface of the pellet in the case of endothermic or weakly exothermic heat of the reactions, and it moves towards the center as the exothermic heat of reaction or the activity energy gets larger. But for negative order or bimolecular Langmuir-Hinshelwood kinetics, it usually locates in the pellets except for severe endothermic or diffusion-control reaction. Both finite thickness of the active layer and a deviation from the optimal location x decrease the value of the E. F. It was shown numerically that the E. F. decreases slightly with an active layer at the inner side of x but seriously at outer side.

The determination of interfacial area in a packed column by the "chemical method" has been studied with absorpton of pure CO2 in carbonate buffer solutions in the presence of AsO2- or C1O- catalyst respectively. The mass transfer data were treated by means of the Danckwerts surface renewal model and the modified surface film renewal model, and then compared. It was shown that the specific interfacial area "a" calculated with these two models were very close to each other, while the values of the renewal frequency "S" seemed to be quite different. The average difference of the values of "a" measured with the two catalysts AsO2- and C1O- was +(9.2-15.5)%. In the modified model the transient mass transfer and reaction during the initial gas-liquid contact were considered, and it was proposed that k1θ>2 might be taken as a criterion to determine the gas-liquid interfacial area by the "chemical method", so that the range of value of k1 for absorption systems could be predicted.It could thus be considered that values obtained by the ClO- catalyst system when determining "a" and "S" were more correct. Moreover, experiments on physical absorption were carried out with the CO2-Na2SO4 system in the same packed column, and the results were correlated with the chemical absorption data. It can be concluded that the modified model seems to be more reasonable for analyzing the operating characteristics of gas-liquid absorption in a packed column.

This paper deals with the macrokinetics of water gas shift reaction on commercial iron oxide catalysts. In an internal recycle gradientless reactor, type B106 and B109 shift catalysts of commercial size and cylindrical in shape, have been studied under atmospheric pressure. Reaction conditions were: temperature 350° to 480℃, molar ratio of steam to carbon monoxide 2 to 11, dry gas space velocity 150 to 1500ml/(h. g). Experimental results showed that the macrokinetic equations for both catalysts can be expressed by the common formula: where pco, pH2o> pco2 and pH2 are the partial pressures of carbon monoxide, steam, carbon dioxide and hydrogen, respectively, KP the equilibrium constant of water gas shift reaction, k* the apparent rate constant. This equation can be used in the simulation of commercial shift converters. The apparent activation energy of B106 catalyst is 14,570 cal/mol and that of B109 catalyst, 16,200 cal/mol. They are approximately one half the corresponding intrinsic activation energy values, suggesting that the water gas shift reaction process is severely limited by intraparticle diffusion on the other hand, the effectiveness factors for both catalysts, as calculated by use of the experimental results and the intrinsic rates indicate that the apparent activity is much lower than the intrinsic activity, hence pointing out the importance of improving the pore structure and geometry of commercial shift catalysts.

The effects of stirrer speed, stabilizer concentration, ratio of dispersed to continuous phase, diameter of reactor and stirrer type, on the mean particle size and particle size distribution were investigated. The results can be correlated by This equation provides a Gfundamental basis for polymerization reactor design and selection of its optimum operating condition.

The operation of the moving bed coal gasifier is strongly influenced by five parameters: steam feed (Fs), oxygen feed (Fo), carbon feed (FC), bed height (H) and blast temperature (TB). These parameters interact closely, so that it is difficult to determine numerically the optimal operating conditions. On the basis of an analysis of the one-dimensional homogeneous model, this paper demonstrates the possible relations among these parameters. numerical computations indicate that an increase of 0.3m in the bed height can sometimes compensate for a decrease of 10-15K in the blast temperature without affecting the residual carbon in the ash and the heating value of the gas product. See Fig. 1. This paper suggests an energy-saving idea for decreasing both steam and oxygen feed at a slight increase of Tmax. For a constant feed of fixed carbon (coal charged, minus moisture, volatiles and ash), a reduction in the steam feed can accelerate the gasification process, while a simultaneous decrease in the oxygen feed can sometimes keep the maximum temperature lower than the permissible value.

The hydrothermal sulfidization process, which has attracted attention in recent years, involves the disproportionation of elemental sulfur in aqueous solution. The kinetics of this disproportionation reaction was carried out. The effect of cupric ions in aqueous solution on this reaction was also investigated. The reaction was carried out in an autoclave. It was shown that elemental sulfur disproportionated in aqueous solutions of pH 6-10 according to the following equation: Experimental results can be correlated by a model of diffusion of elemental sulfur from sulfur droplets to the aqueous solution followed by a pseudo-first-order disproportionation reaction in the aqueous phase. The rate expression has the following form: -ln(1-α)=kt·t where kt = aCs, a is the interfacial area of 1 g of liquid sulfur in water, k1 is the pseudo-first-order reaction rate constant, Cs and D1 are solubility and diffusion coefficient respectively of sulfur in the aqueous phase, α is the fraction of conversion of elemental sulfur, and t is the time of reaction. The effect of pH on reaction rate was studied at 130℃. It was shown that the pseudo-first-order rate constant k1 is directly proportional to the concentration of OH- in the pH range of 6-7.5. The temperature dependence of k, was also studied at pH 6.3 and the apparent activation energy derived was 24.0 kcal/mol.

Pressure drop for flowing mixtures of sized sand particles in water through a vertical tubular leacher has been measured. When the particle size is between 60 and 80 mesh, the volume fraction of solid smaller than 0.175, and the velocity between 0.09 and 1.5m/s, the operation is stable. For different solid/liquid ratios, all experimental curves for pressure drop versus flowing velocity show minima, and the greater the solid/liquid ratio, the higher the flowing velocity at which the minimum occurs. The gravitational pressure drop for vertical tubes is given by △pg = △ε(ρs-ρf)gH. The difference in voidage between the up-and down-flow tubes may be calculated by equations for generalized fluidization, and is approximately equal to △ε= 2q/(1 + q)"+2R. The frictional pressure drop for vertical tubes may be calculated by treating the solid-liquid mixture as a continuum by other existing correlations.

Hydrodynamic data of sieve trays with hole diameters of 5, 10, 15, 20 and 25 mm were experimentally obtained and studied. A set of equations to correlate pressure drop, weeping velocity, entrainment and froth height was established, and was considered precise enough for design requirements. The performance and operating flexibility of large-holed sieve trays were studied and discussed. It can be shown that for properly designed sieve trays, operating flexibility can be achieved with a loading ratio 2 to 4, which is adequate for fluctuation of commercial-scale columns.

Liquid polybutadiene(cis-1, 4 = 45-60%, trans-1,4 = 10-40%, vinyl = 15-40%, Mn=1500-6000) was prepared by using Co (naph)2-AliBu3-PhCCl3 as catalyst, extract gasoline as solvent and ethylene, propylene, isobutene as molecular weight regulator. The effect of α-olefine to butadiene molar ratio, polymerization temperature, monomer concentration, polymerization time on conversion, number-average molecular weight and microstructure of the productwere investigated. The adjusting mechanism of α-olef ine was proved.

Mass transfer in the falling film of laminar non-Newtonian liquid was studied experimentally. A wetted column was used to measure the rate of absorption of carbon dioxide in aqueous polymer solutions, the rheological behavior of which is well characterized by the power-law model. The experimental results showed that the exact solution of the differential equation of diffusion, which considers the velocity distribution in the falling film of non-Newtonian power-law fluids, are proper. It was found that for pseudoplastic fluids it is adequate to use the dimensionless length Z<0.1 as the criterion for the applicability of the penetration theory, which the exact expressions would be applicable to the entire range of the dimensionless length.

This paper deals with an experimental study on the rate of heat transfer in helical ribbon mixers and its relation with power requirement. Four ribbon impellers and eight test fluids of different consistencies and ranging from pseudoplastic non-Newtonian to highly viscous Newtonian were used in the experiment. It was found that heat transfer coefficient is a function of impeller geometry at Reynolds number less than about 0.1.Accordingly there are four correlations corresponding to the four ribbon impellers. At Reynolds number higher than 10, Heat transfer coefficient is independent of impeller geometry and a single correlation is therefore obtaind for all the four impellers. Since both the heat transfer coefficient and power consumption are functions of Reynolds number, a relation is presented between them.