The wake model based on the wake concept of Stewart and Davidson divides the bed into three regions : bubble, bubble wake and particulate fluidiza-tion. It can predict only the mean value of phase holdups, but not their radial distribution. The authors reported in their paper presented at the 5th conference of Fluidization in Denmark 1986 year, a four-region model to account for liquid vortex with a few solid particles. In this work the radial distributions of local holdups and liquid vortex in G-L-S two-dimensional fluidized bed were measured by conductivity probe with microcomputer-sampling technique. The experimental results show that the liquid vortex holdup is equal to almost zero at the center and near the wall and has a maximum value at about the position r/R =0.7. On the basis of experimental data, the bed could be divided into gas bubble, gas bubble wake, liquid vortex and solid liquid fluidization regions. A four-region mathematical model of calculating the phase holdups was developed and gave a good match to the experimental da-ta. The four-region model can not only simulate the distributions of phase holdups in the radial direction, but also predict the contraction of a three-phase fluidized bed.

A general unsteady state solution is obtained by means of Greens function for a dispersion-type tubular reactor with a non-flow zone. Arbitrary initial concentration profiles along the reactor for the flow zone and the non -flow zone are allowed and the feed concentration is time-varying. Firstly a self-adjoint operator is defined and the Greens function is constructed, then the unsteady state solution is found from the Greens function.

In this work, the characteristics and enhancement of pervaporation for the separation of alcohol-water mixtures especially for ethanol-water azeotrope, have been demonstrated with several kinds of membranes such as CTA, PSf, PVAc/PSf, PAA-PAN/CA, etc. along with the investigation of a modified solution-diffusion model. In addition to the determination of separation factor and permeability, the effective direct determination of solubility of solute (or solvent) inside the membrane was carried out by a novel device coupled with GC-103. Meanwhile, the diffusivity was determined by a transient approach and pervaporation separately. A multicoefficient diffusion model was correlated. The results conform with the theoretical prediction and would provide the scientific basis for further industrial application.

This paper presents the research work on the mechanism of flow regime transition (from bubbling to turbulent fluidization) in gas-solid fluidized beds. Combined with statistical measurement in time domain, coherence function was employed to analyze the pressure fluctuation in the bed. When the breaking of bubbles dominates over coalescence, turbulent fluidization occurs. This mechanism was directly proved by the experimental results.

In this paper a general correlation has been developed on liquid dispersion in three-phase fluidized bed reactor based on the principle of energydissipation. Liquid dispersion can be described by the characteristics of turbulence of fluid as well as geometric parameters of the reactor. Correlation of recently published data can be represented as PeL= 3.31(Fr")0.35, in which Fr" is the modified Froude number. The above relation is very close to the theoretical relation with Fr" covering a wide range of 6 orders of magnitude and a correlation coefficient R=0.98.

The mechanism of the formation of formic acid and sodium bicarbonate by GLLDD has been studied. The absorption rate of CO2 by the organic phase was found to be almost ten times that by sodium formate solution. It was also shown by experiment that the mass transfer of CO2 from the gas phase into the aqueous phase proceeded essentially through the organic phase rather than directly. CO2 was absorbed in the organic phase before reacting with sodium formate solution to form NaHCO3 and complex amine carbonate. The organic phase was both the extractant of formic acid and the transporter of CO2.

The mechanism of the colloidal protection of aqueous dispersions of C. I. Disperse Blue 79 by nonionic surfactants (as dispersing agents) was studied. A good correlation of the settling parameter, electrokinetic properties and adsorption isotherms of surfactants on the surfaces of the dye particles was obtained with these dispersions. The results show that the stabilization of the dispersions by the surfactants is achived by their adsorption on the dye particles, and an optimum surfactant concentration corresponds to the best stability of the dispersions. It is considered that the adsorption layer might influence the structure of the electric double layer by the so-called squeezing effect.

Modified photo-electric capillary probe technique with improved sampling accuracy was used to measure bubble size distribution in an aerated stirred vessel. Simulated calculation indicates that the ratio of Sauter mean diameter or standard deviation to maximum diameter can approximately keep constant despite of change in operating conditions. The main factors governing the bubble size in impeller region and in circulation region have been deduced according to turbulence theory. Experimental findings show that the probability density of bubble diameter approaches that of normal distribution in air-water systems. There exists obvious difference in magnitude between bubble diameter in impeller region and that in circulation region. The quantitative relations between the Sauter mean dimeter in different regions and the power per unit volume, superficial gas velocity and the ratio ot impeller diameter to tank diameter have been given.

Based on the analysis of some equivalent diameters of non-spherical particles, both the Stokes diameter and Newton diameter are recommended as the characteristic dimensions of non-spherical particles settling in the intermediate region. Through the use of Kaskas correlation on drag coefficient, a new equation for estimating the terminal falling velocity has been derived as following: The equation is applicabe to both Stokes Law region and Newtons law region. The characteristic dimensions were dependent upon the size distribution. The data from sieve analysis were processed with cubic spline function interpolation, and two equations for estimating the nominal diameter were derived for the particles settling in Stokes law region or Newtons law region respectively. The nominal diameter may be modified by shape coefficient to obtain the Stokes diameter and Newton diameter. A series of experiments carried out in a fluidized bed equipment showed that the calculated values fitted well the experimental data.

By combining a pseudo-binary model with the Barkers method, it ispossible to predict the vapor phase mole fractions of a three-component salt-containing system from the relative P-T-x, data. The predicted values were compared with the experimental ones, point by point, to test the thermody-narnic consistency of VLE data. The isobaric VLE data for alcohol (ethanol, isopropanol)-water-salt(CaCl2, KAc)systems were tested, and good results were obtained. The success in predicting vapor phase mole fractions from P-T-x data paves the way for improving the determination of VLE for salt-contain-

In the multi-solvent salt-containing solutions, there are different solva-tion effects surrounding salt ions for different solvation effects surrounding salt ions for different solvents. The present work combine a model of solvation for the solvents around the salt with activity coefficient correlation or MH-81 equation of state to correlate vapor liquid equilibria of more than forty salt-containing systems. The calculated valuer were in good agreement with the experimental data.

Permeation of pure gases and binary gas mixtures through glassy polymeric membranes have been investigated. The separation factors of Langmuir permeation environment αH and Henry permeation environment αD, were introduced and their relationship with apparent separation tactor α was derived. The effects of feed pressure, composition, temperature and glassy transition of polymer on selective permeability were analysed and the applicabilities of dual-sorption dual-mobility model and its extended formula used for the description of permeation of gas mixtures were also verified experimentally. The phenomena occurring sometimes in practice that "the presence of a slow gas can reduce the permeability of a fast gas, the presence of a fast gas can increase the permeability of a slow gas" and that "the ratio of permeabilities of pure gases is usually larger than the practical apparent separation factor" were discussed with theoretical analysis and experimental data. It was found that these phenomena are not universal and may change conversely un-der specific conditions.

In this paper the effect of distributor pressure drop on the state of flu-idization is analyzed. A mathematical model is proposed for the absence of partial fluidization and channeling in the bed. According to the distributor pressure drop and fluid velocity the regions of channeling, partiaJ fluidization and full fluidization are divided. The results form a new basis for the rational design ot the distributor.

The Variations of hydrodynamic, heat and mass transfer behavior for systems of type B particles (according to Geldart s classification) with the addition of type A particles have been investigated. Based on experiments of more than twenty different systems composed of particles of FCC(A), A12O3 (A). AN(B)and CA(B), the correlations for the calculation of incipient fluidiza-tion velocity, incipient bubbling velocity and heat transfer cofficient of the bed to immersed surface have been obtained. Furthermore, a criterion for the classification of particle mixtures has been proposed, and the interphase mass transfer coefficients between bubble phase and emulsion phase have been determined and quantitatively analyzed.

In liquid-phase oxidation of hydrocarbon by air, liquid carryover in the off gas returns to the reaction system from the condeser and separator. There are three modes of carryover return, as shown in Fig. 1: backward refluxing, refluxing in situ and forward refluxing. It. is apparent that the reactant concentration distribution would vary in the reactors in series with the mode of carryover return, thus affecting the overall oxidation process. In this paper, the influence of the mode of carryover return and the reflux ratio on hydrocarbon conversion and selectivety for hydroperoxide formation are discussed. It is shown that in backward refluxing, both conversion and selectivity may be improved if the carryover consists mainly of hydrocarbon, and one obtained: Lim R→∞ Sb=1

A fluorometric-tracing technique with optical fiber detecting and microcomputer data acquisition was developed and applied to the studyof tray entrain-ments. The proper structure of the optical fiber probe, the disturbance of gas bubbling, the liquid collecting device, and the location of detection etc. were investigated. In comparison with the traditional weighing method, this system is superior to the former in quick, sensitive and reliable measurement and continuous measurement of entrainments on any tray in question.

A thermodynamic model of vapor-liquid equilibria in NH3-H3PO4-HO system has been studied. In the vapor liquid equilibria calculation by using extended Pitzer equation, water activity and solute activity coefficients in aqueous phase were obtained. By the modified Redlich-Kwong equation of state, vapor phase fugacity coefficients were obtained. Based on the assumption of Edwards et al (1975) of the molecular thermodynamics of aqueous weak electrolytes, a molecular thermodynamic correlation was established to calculate vapor liquid equilibria in NH3-H3PO4-H2O system. The correlation model calculated data agreed well with the experimental equilibrium vapor pressure data up to concentrations 25 mol/kgH2O.