A new model for liquid membrane mass transfer is developed. This model takes into account botb the permeation process of solute through the inner core of emulsion globule and the effect of interf acial resistance enhancement caused by surfactant, thus providing reasonably accurate predictions for the mass transfer process in a liquid membrane system. Another feature of the present model is that the factor of membrane leakage isincluded in the model descriptions. This suits the mode] further to the practical conditions of the system. Both experimental results and theoretical analysis show that molecular diffusion through the very thin liquid layer of surfactant existing at the interface between emulsion globules and the continuous phase is the rate-controlling step for mass transfer in a liquid surfactant membrane system. This conclusion will lead to a deeper understanding of the membrane structure and will be helpful for improving membrane systems.

The kinetics of cobalt extraction with P5709 has been studied in a Lewis cell. The aqueous phase consisted of Co2+ (0.5-5g/l) and Na2SO4 (9%) at pH = 5.5, and the organic phase, 15%(V/V) P5709 and 85%(V/V) kerosene, saturated with hydrogen. In order to determine the controlling regime of the extraction process, the stirring speed, the interface area between the two phases and the op-erating temperature were varied in the experiments,the results showed that cobalt extraction with P5709 was,mainly diffusion-controlled, with the following overall mass-transfer coefficients: Both experimental and calculation results showed that neither Kw nor Ko remained constant during extraction. The reasons for this variation wera discussed.

This paper deals with the conditions for criticality and other related problems for the continuous-flow stirred tank reactor(CSTR) operating adi-abatically under steady state. A new technique for analyzing the thermally sensitive region of adiabatic CSTR is discussed, and mathematical expressions for two important thermally sen sitive boundaries, ignition and extinction, are given. A new concept on the transition phenomenon or the dis appearance of criticality is pointed out theoretically, and expressions for the conditions of this transition to occur are given. The present paper finally discusses the times-to-ignition for marginally supercritical systems, which are very close to the thermally sensitive boundary of ignition.

The maximum profit policy in the operation of a batch distillation column separating a binary mixture has been studied. A generalized mathematical model was derived with consideration of tray efficiency and liquid hold-up in the plates and the condenser. The optimal scheme of reflux control was worked out by a digital method. Computation showed that the proposed optimal control scheme could lead to much higher profit than the conventional mode of operation using constant reflux ratio or constant overhead composition. To demonstrate the practical usefulness of the proposed scheme, experimental work was conducted for the separation of ethanol-water mixture in a 0.17 meter diameter batch distillation column which was operated both under the optimal reflux control scheme and according to the conventional mode of constant reflux ratio. The economic profit obtained from the former operation was found to be 207% higher than that from the latter, the theoretically predicted value being 220%.

The thermodynamic properties of aqueous NaCl solutions at high temperatures and pressures are important for many industrial and geological systems and also possess theoretical significance. It is shown that a very simple semiempirical equation can be used to represent the composition of aqueous sodium chloride solutions up to saturation over the range, 373-573 K and 0.1-100 MPa. This equation comprises a term of long-range electrostatic force derived from the well-known osmotic pressure equation by statistical mechanics, and another term of short-range intermolecular (or inter-ionic) force deduced from the non-electrolyte solution theory. The excess Gibbs energy of aqueous NaCl solutions can thus be expressed as follows:The activity coefficient of water and the mean ionic activity coefficient of NaCl are respectively. In the above equations, the pure liquid H2O and the supercooled liquid NaCl are taken as reference states, and the mole fraction on an ionized basis as the measure of composition. Only parameter w is freely adjustable, because all the other parameters are determined by the properties of pure water. A simple programmable calculator is adequate for the calculations. Agreement of the calculated osmotic coefficient (φ) with the experimental is excellent, the standard deviation of φ being ±0.0076 for the range 373-573 K at saturation pressure. According to the physical meaning of w illustrated by the Scatchard-Hildebrand theory, the large and negative value of w at low temperatures represents a dominance of ion hydration over the other inter-particle interactions. The Gibbs energy of fusion of NaCl in the range 373-573 K is obtained The calculated chemical potentials of NaCl in aqueous solutions with different reference states coincide with one another, showing the reliability of the equations.

Vapor pressures were measured by the static twin-ebulliometer method at five temperatures adjacent to the normal boiling point for solutions of calcium chloride in water, in methanol and in ethanol, and for solutions of potassium acetate in water and in ethanol. The cubic chain-of-rotators (CCOR)equation of state was used to correlate the experimental data. The average deviation of correlated results is ±0.42%. The parameters of the CCOR equation of state obtained can be used for calculating vapor-liquid equilibria for other salt-containing systems.

The rubber(R) phase and polystyrene (PS) phase of high impact poly-styrene(HIPS)prepolymer were separated by means of ultracentrifuge, in order to investigate their rheological behavior separately. Below 17% conversion, the rheological behavior of the PS phase is Newtonian, and this viscosity can be estimated by where CPS and Mw, are, respectively, wt% concentration and weight-average molecular weight of PS in the PS phase, while above 17% conversion, the PS phase begins to exhibit pseudoplastic behavior, with its apparent viscosity rising drastically as the conversion increases. On the other hand, the R phase shows pseudoplastic behavior during the whole range of prepol-ymerization, and its apparent viscosity can be correlated with the graft de-gree(E)and the concentration(CR)of rubber as well as shear rate(r)bywhere The influence of conversion and shear rate on the two-phase viscosity ratio (ηR/ηps)were also discussed. Finally, viscosities of the prepolymer system and of its two phases were correlated by the following equation, which was derived from an alternative layer model Where A and B are adjustable parameters, φPS is volumetric fraction ot polystyrene.

A semitheoretical equation, log P=A- (B/TN) (I), and an empiricallymodified Antoine equation,logP= A-(B/T-C)+DTM(Ⅱ), are proposed for cor- relating liquid pressure with temperature. These two equations together with the regular Antoine equation, logP=A-(B/T-C) (Ⅲ), and the equation, logP = A-(B/TN) + CTM (Ⅳ), proposed by Thodos et al., have been used to fit the high-pressure data of 1631 points for 68 substances, published since 1962 through 1982. The results show that all these four equations are applicable up to the critical points. The grand average deviations between the calculated and experimental values are about 0.4% for the three-constant equations ( I ) and (Ⅲ), and about 0.2% for the four-constant equations(Ⅱ) and (Ⅳ). The effect of adopting different values of M in equations (Ⅱ) and (IV) is not significant, and M=l is therefore suggested. The values obtained for the parameters of equations ( I ) and ( Ⅱ) are presented for the 68 substances. The three-constant equations ( I ) and (Ⅲ) are recommended for general use, equation (I) being more convenient than (Ⅲ) for mathematical treatment.

In this paper a generalized extension of the block correction technique is developed including formulae for a multiple block(arbitrary number of blocks)correction technique, and the effect of the number of correction blocks on convergence is studied, with the following findings: 1. There is an optimal number of correction blocks for a problem, for which the CPU time is the smallest. 2. As the number of grid points in the calculation domain increases, the optimal number of correction blocks increases. Generally speaking, when the number of grid points between 20×20 and 10×10, double block correction is the best, when the number of grid points is about 30 × 30, triple block correction might be the best, while if the number of grid points is even greater, multiple block correction may be needed to save computer time. 3. Boundary conditions may have a significant influence on the optimal number of blocks. In general, boundary condition problems of the second type may nead more blocks in the correction technique than the first type.

Experiments on radial dispersion of a gas stream in three different types of packings were carried out in φ200- and φ287- mm perspex columns with CO2 as a tracer. The packing used were corrugated plate with 4.5- or 6.3- type extruded holes, 15-mm Raschig rings, and 25-mm cascade rings. Experimental results indicated that the corrugated plate packing has an excellent radial dispersion behavior. The value of Peclet number Per depends on the height and diameter of the packing element, inclination angle of corrugation and the Reynolds number Re. Peclet number increases with increasing Re at low Re, but approaches a constant value as Re>800.

According to structure and fluid flow characteristics, the mixing mechanism of a gas stream in the corrugated plate packing was analyzed. Three types of mixing were identified: 1. Mixing at the channel intersections between adjacent plates, 2. Mixing near the wall region, 3. Mixing at the interface between adjacent elements. A mathematical model with three parameters has been proposed for predicting the radial concentration profile at a given height. The results showed that the predicted values fit the experimental data satisfactorily.

In order to improve the rotating-flow-plate separator to remove smaller particles at higher gas velocities, especially for preheating cement raw mix, a series of three-dimensional measurements were conducted and the experimental results were analyzed. Based on the flow profiles thus elucidated, the following improvements were made: a baffle plate was installed around the rotating-flow-plate to prevent particles from backflow, and a rib along the wall of the separator was added to counteract dust-ring whirling near the wall. These improvements resulted in lowering the critical diameter of the particles separated to 10-15μm at a gas velocity of 3 m/s. Formulae for critical particle diameters and data on pressure drop of the improved separator are presented.

Liquid adsorption in fixed bed was studied at room temperature for the binary system, para-xylene and ethylbenzene, with two types of zeolites- one prepared by our group, and the other imported. The mathematical model included a mass transfer equation involving the total mass transfer coefficient, and the equilibrium and the mass balance equations. These three equations were integrated numerically. The predicted breakthrough curves was close to the experimental. To explore further the mechanism of mass transfer, three models-liquid-phase controlling, solid-phase controlling and both-phase controlling were examined. The results showed that the solid-phase controlling model is the most appropriate for a system studied.