HYDRODYNAMIC CHARACTERISTICS OF THE PROCESS OF DEPRESSURIZATION OF SATURATED WATER

Experiments were carried out to find the effects of dissolved gas pressure,liquid flow rateand nozzle geometry on the bubble generation when saturated water was depressurized through anozzle.A new method,high speed camera system was developed to measure the generated microbubblesdynamically.On the basis of the laws of ideal gas and solution,theoretical generated gas flow ratewas deduced,while the Smoluchowski′s equation was applied to describe the kinetics of bubblenucleation.It was found that the size distribution of nucleated bubbles was of skewed distribution.An explanation to this phenomenon was made and the Gamma function distribution was employedfor mathematical simulation.The results show good agreement between the experimental data and thepredictions by proposed model.     

THE CALCULATION OF CRITICAL PROPERTIES OF MIXTURES FROM EQUATIONS OF STATE

The rigorous critical state criteria based on Helmholtz free energy is used with equations of state fordirect calculation of critical properties(T_c,P_c and V_c)of 44 binary and 5 ternary systems.Special at-tention is paid to systems containing polar component(s)and the improvement in critical volume prediction.For extending this method to polar systems,the recently developed Cubic Chain-of-Rotators equation ofstate has been applied.As compared with SRK and PR equations of state,the improvement in V_c pre-diction is most impressive.     

CALCULATION OF THERMODYNAMIC PROPERTIES OF FLUID MIXTURES WITH A NEW EQUATION OF STATE †

The subject of this paper is the evaluation of the applicability of constant temperature anemometry (CTA) with a modified version of Delhaye's method to aerated stirred tanks. A calibration technique that takes into account the variation in medium temperature was developed and verified experimentally. The directional sensitivity of the conical film probe was investigated in a streamline flow field as well as in the impeller discharge stream in an stirred tank.

The reliability of the setup and the technique was verified through the comparison of the vertical and radial velocity profiles of water in a stirred tank with those obtained from the literature. The directional response of the conical probe follows the cosine law for intersection angles smaller than 45° in a streamline flow field, but the directional sensitivity in the impeller discharge stream is rather poor, owing to the rolling characteristics of flow in this region. Due to the inability to detect bubbles smaller than the sensing element of the conical probe, the CTA usually gives lower values of local gas holdup. However, this discrepancy is considered to have no influence on the velocity measurement.     

EFFECT OF MAGNETIZATION OF WATER ON INDUCTION TIME AND GROWTH PERIOD OF NATURAL GAS HYDRATE

The effect of diluted solution's magnetization on induction time and growth period of natural gas hydrate (NGH) has been investigated in quiescent reaction system at pressure of 4.5 MPa and temperature of 274 K with SDS as surfactant, by using volume fixed and pressure falling method. Experimental results show that magnetization will have effect on the induction time of NGH. After magnetization with magnetic field intensity of 0.33 T, the induction time of NGH has been reduced to 47 min (average) from 99 min (average) in which there is no magnetization. On the other hand, the induction time has been prolonged after magnetization of the diluted solution with magnetic field intensity of 0.05 T, 0.11 T, 0.22 T, 0.44 T. Especially with magnetic field intensity of 0.11 T, the induction time had even been prolonged to 431 min (average). The effect of magnetization on the growth period of NGH has not been found at the experimental condition.     

EXTENSION OF SOAVE EQUATION OF STATE TO LIQUID DENSITY

On the basis of vapor pressures, volumes of saturated vapor and liquid, both parameters "a" and "b" in Soave equation of state are treated as temperature dependent and an extended Soave equation is proposed in this work. The VLE for 38 pure components including polar substances have been calculated. The comparison of calculated results with experimental data shows the prediction of liquid density is improved over Soave equation without losing the accuracy of prediction in vapor pressure and vapor density.     

KINETIC STUDY OF THE CATALYTIC STEAM REFORMING OF PARAFFINS

Kinetics of the steam reformig of n-butane,n-hexane,n-heptane,n-nonane and i-octane on Z409 catalystwere studied at atmospheric pressure by using an internal recycle gradientless reactor.The reaction temperaturewas varied in the range of 743-853K,the steam carbon molar ratio 3-5.The experimental results showed thatthe reforming products contained no hydrocarbon other than methane.In addition,the product distributionof different n-paraffins were similar,but the product distribution of i-octane was different from that of n-paraffins.A reaction scheme for the steam reforming of paraffin has been proposed and the hyperbolic type rateequations were derived.It is clear that the obtained kinetic model could simulate the experimental results ofi-octane as well as different n-paraffins satisfactorily.     

KINETICS OF PHASE TRANSFER CATALYZED DISPROPORTIONATION OF ELEMENTAL SULFUR

The kinetics of phase transfer catalyzed (PTC) disproportionation of elemental sulfur was studied in the range of OH~- concentrationlin the aqueous phase from 0.02 to 0.14 mol/dm~3 and temperature from 45 to 70℃. A kinetic expression, R_sa=k*[Q~ ]_(aq)[OH~-]_(aq)[S]_(org)~(1/2), derived from the theory of mass transfer with rapid chemical reaction in liquid liquid system can be adopted to correlate the experimental data, and the apparent activation energy of the reaction was found to be 79kJ/mol. Kinetic evidence for PTC reaction of the system was given and a mechanism of PTC disproportionation of elemental sulfur was proposed.     

EXTENSION OF MARTIN-HOU EQUATION OF STATE INTO LIQUID REGION

The range of application of the equation of state proposed by Martin and Hou for gases was extendedinto liquid region.The improvement was achieved by retaining the constant,B_,in the original equation,namelyP=(RT)/(V-b)+(A_2+B_2T+C_2e~(-5.475))T_r+(A_3+B_3T+C_3e~(-5·475))T_r+(A_4+B_4T)/(V-b)~4+(B_5T/(V-B)~5)and imposing the condition,PdV=P_0(V_v-V_l),on the equation.The constant,B_4,was then evaluatedfor a given compound.The calculated values of the saturated liquid molar volumes for carbon dioxide,normal butane,argon,methane and nitrogen,were compared with the data reported,in the reduced temperature rangefrom about 0.65 to 1.0.The average deviation was less than 5% in each case,without loss of accuracyin gaseous region.Furthermore,no additional data were required for evaluation of the constants of theimproved equation.     

SYNTHESIS OF UNSATURATED POLYESTER RESIN—EFFECT OF CHOICE OF REACTANTS AND THEIR RELATIVE PROPORTIONS

Unsaturated polyesters are synthesized in the laboratory by the condensation of saturated and unsaturated anhydrides with glycols. The condensate obtained is mixed with styrene monomer to get an unsaturated polyester resin formulation. The properties of the polyester resin synthesized are affected by the synthesis parameters. In this study, the parameters investigated are the effect of choice of reactants and their relative proportions. Properties such as tensile strength, tensile modulus, elongation-at-break, toughness, impact strength, surface hardness, abrasion resistance, and water absorption were tested after curing the resin. Various combinations of (a) maleic anhydride and phthalic anhydride, (b) propylene glycol and ethylene glycol, and (c) propylene glycol and diethylene glycol were used to investigate the effect on the properties of the synthesized resin. The combinations of the anhydrides and glycols that give optimum properties are identified. The results show that most of the properties are maximum at 60% maleic anhydride composition in a mixture of maleic anhydride and phthalic anhydride. Similarly, a better balance of properties is obtained when propylene glycol is mixed with 30% ethylene glycol or 20% diethylene glycol.     

MEASUREMENT OF TURBULENT FLUCTUATIONS OF VELOCITY GRADIENT ON THE WALL WITH A PAIR OF SEMICIRCULAR ELECTRODES

Measurement of turbulent fluctuations of vclocity gradient on the wall is important for thorough understanding of turbulence structure, mass transfer and heat transfer in the vicinity of the wall. This paper describes the principle of electrochemical technique as well as the measurement of two-dirnensional fluctuations of velocity gradient with a pair of semicircular electrodes. In a fully developed turbulent pipe flow with pipe diameter of 0.194 m and with a solution of iodine and potassium iodide as flow medium, the measured axial and transversal turbulent intensities of velocity gradient at the wall arc 0.3-0.33 and 0.11 0.12 respectively.     

OPTIMIZATION OF FLOW RATE OF MOBILE PHASE IN COUNTERCURRENT CHROMATOGRAPHY

1 INTRODUCTIONCountercurrent chromatography(CCC)[1,2] is distinguished from other chromatographicmethods by its eliminating the solid support matrix from the separation column.Themethod employs an open tubular column where the partition process takes place be-tween the flowing mobile phase and the stationary phase retained by the effect of gra     

KINETICS OF THE DECOMPOSlTION OF SCHEELITE CONCENTRATE BY LEACHEX PROCESS

The new method named as LEACHEX process which combines leaching of minearl and extraction of metalfrom leaching liquor is used to proccss scheelite concentrate.Elimination of solid film consisting of tungstic acidand the controlling step of chemical reaction are illustrated and an empirical kinetic equation is proposed basedon unreacted-shrinking-core model.90 percent decomposition of scheelite can be attained in 1800 seconds.     

DETERMINATION OF THE SOLUBILITIES OF 2,4-DICHLOROBENZALDEHYDE IN ORGANIC SOLVENTS

Solubilities of 2,4-dichlorobenzaldehyde in five single organic solvents,namely,n-propanol,n-butanol.cyclohexane,chloroform and dichloromethane as well as in two mixed solvents,namely,cyclohexane-acetone and cyclohexane n-butanol,have been measured.These data are correlated withWilson,NRTL and UNIQUAC activity coefficient models and can be used for the process design inthe purification of 2,4-dichlorobenzaldehyde.     

KINETICS OF THE EXTRACTION OF COBALT WITH EXTRACTANT P5709

The kinetics of extraction of cobalt with P5709 was studied in a Lewis cell. In the extraction system the aqueous phase was the solution of CoSO_4 (8.8×10~(-4)—3.4×10~(-2)M) and Na_2SO_4 (0.63M.) at pH 5.5; the organic phase was 15% (v/v) P5709 in kerosene (saturated with hydrogen).In order to determine the control regime of extraction of cobalt, the stirring speed, the interracial area between the two phases and the operating temperature were varied in the experiments. Experimental results showed that the extraction process of cobalt was predominantly governed by the diffusion process, and the overall mass transfer coefficients were found to be as follows:_((a)): (2-5)×10~(-3)cm/s, _((o)): (0.3-1)×10~(-3)cm/s.The results of the experiments and calculations indicated that K did not remain constant during the extraction process, Reasons for the variations in K were discussed.     

STUDIES ON CYANATION OF O-HALOGENATED AZO DYES(Ⅰ)IDENTIFICATION OF THE PRODUCTS OF THE CYANATION

The molecular structures of the products of the cyanation of 2,6-bromo-4-nitro-4′-(N,N-diethy1)-azo dye withCuCN were analyzed and identified.Mechanism of the formation of the by-products was also discussed.     

EFFECT OF FLOW PATTERNS ON EPOXIDATION OF PROPYLENE WITH ETHYLBENZENE HYDROPEROXIDE

The process of producing propylene oxide by epoxidation of propylene with ethylbenzene hydroper-oxide is one of the most promising methods in recent years.In order to select an optimum reaction equip-ment technologically,the mathematical models of epoxidation reactor for plug flow,single-stage andmultistage perfect mixing have been founded in this paper by means of the kinetic model on epoxidationand the effects of various flow patterns on the reaction are also discussed.The analyses show that themultistage reactor is a more ideal one for industrial equipment,and its optimum operating conditions aresuggested.