The first part of this paper concerns with optimum reflux ratio of packed column for close-boiling fractionation. A correlation is proposed to find the NTU at finite reflux and from which a graph representing the optimum reflux ratio is derived. It is found that the maximum value of optimum reflux ratio is about 1.4Rm. The second part of this paper concerns with optimum ratio of column diameter to packing size. Experimental work has been conducted with four laboratory columns of 20, 28,32 and 44 mm in diameter respectively, the height of packed bed ranging from 1020 to 1475mm, the packing used being 2.5x2.5 mm angular helices and the testing system to be n-heptane-methylcyclohe-xane. The true separation efficiency (i. e. true HTU or true NTU per meter of bed height)is evaluated from the experimental composition profile by discarding the end effect at the top and the bottom ends of packing. By plotting the true separation efficiency versus the ratio of column diameter to packing size, all the curves at constant vapor velocity exhibit an optimum reflux ratio with nearly identical value. The optimum reflux ratio for this packing is found to be 13-14 which is in rough agreement with that for ordinary or industrial size of packing.

A new type of internal baffles has been developed for the purpose of improving the performance of gas-fluidized bed. The fluidizing behavior of the new pagoda type baffles has been studied in a two-dimensional bed in comparison with those of other types, and both photographs and moving pictures have been taken to demonstrate their viability in breaking up bubbles and enhancing gas-solid contact. The pagada baffles installed in a 30-cm-dia. pilot plant fluid-bed reactor for manufacturing phthalic anhydride from catalytic oxidation of naphthalene have been found to increase the feed load from 50-100 to 100-160 grams per hour per kilogram of catalyst, as compared to horizontal baffles originally used in the same reactor, corresponding to an increase in duty of 50 to 100%. The experimental data has been treated with a two-phase model. Results show that fluidized reactor with pagoda internal baffles has a very high interchange coefficient between the bubble phase and emulsion phase.

Studies were made on certain characteristics of gas-lift reactor. This type of reactor is called Pachuca tank in hydrometallurgy and is used widely as gas-liquid-suspended solid particles 3-phase reactor. Methods were developed to calculate gas-liquid and gas-liquid-solid particles circulation capacity through the central tube of the reactor based on energy balance principle. Starting from the force balance on a solid particle, equations with dimensionless groups were also developed to calaulate the critical settling velocity of particles at the reactor bottom. Based on experimental results, the critical plug-up velocity of reactor can be calculated by an equation developed. Results can be used for the design and operation of this kind reactor.

A mathematical model using zone method to calculate radiating heat transfer is described. In the zone method, the system is divided into surface zones and gas zones and the number of which depends on the accuracy of results desired and calculation time required. The temperature profiles in a furnace are obtained by solving simultaneously energy balances on each zone. As originally developed by Hottel and Cohen, the direct exchange areas are limited to cubes and squares. In this paper, the derivation of the direct exchange area equations is extended between any two zones in the box or cylindrical furnace.These equations are adaptable to any dimension of rectangles, coaxial cylinder walls, end rings and other shapes. A design method for the primary reformer of hydrogen production unit and cylindrical furnace is proposed. By considering the reaction kinetics,convective heat transfer and pressure drop inside the tubes, the zone method has been adopted to predict temperature profiles of process gas, furnace gas, tube surface and refractory surface in such furnaces. Results of calculation agree well with data obtained from commercial units.

Starting from non-isothermal excess enthalpy data (two or more than two sets) and isothermal vapor pressure data (one set), and based on the principle of corresponding states of solutions, a complete computation procedure of vapor-liquid equilibrium data is proposed. (1) Calculation of excess enthalpy HE, based on the principle of corresponding states of solutions; (2) Calculation of Gibbs free energy GE or its Q function; (3) Calculation of bubbling point; (4) Calculation of vapor-liquid equilibrium data. The computation results for benzene-cyclohexane, benzene-n-hexane, benzene-n-heptane, benzene-n-octane, carbon tetrachloride-benzene, carbon tetrachloride-cyclohexane and carbon tetrachloride-n-heptane, compared with the corresponding vapor-liquid equilibrium experimental data are quite satisfactory. The proposed computation procedure is appropriate to non-polar and slightly polar binary systems under relatively low pressures.

The four well-known activity coefficient models (Wilson, NKTL, McCann and UN1FAC),coupled with virial equation and tridiagonal matrix method, have been successfully applied to the vigorous computation of various non-ideal distillation processes. The N1DISTL program developed by authors has been tested for 33 distillation systems, with more than on hundred calculations performed. To make a parallel comparison of these activity coefficient models, 18 sets of binary vapor-liquid equilibrium data were chosen, each set was fitted to Wilson, NRTL and McCann equations respectively by using non-linear least square technique. The binary parameters so determined were used to predict the bubble point equilibrium data of 18 binary and 8 derived multicomponent systems. The predictions of four models were compared with experimental data. To illustrate the consistency of distillation calculation results using different activity coefficient models, four examples were presented. The temperature, flow rate and composition profiles calculated were compared and the cause of discrepancy in some cases were discussed.

With the aid of fundamental correlations of statistical mechanics and some assumptions,a simple method for calculating pseudocritical constants of mixtures containing nonpolar and slightly polar components is proposed in this paper. A detailed comparison of pseudocritical constants by this method with that by Lee-Keslers rule has been made. Finally, using this method together with Lee-Kesler tables, compressibility factors for some gas mixtures have been calculated, obtaining good agreement with experimental data.