A direct method for evaluating equilibrium vapor compositions from measurements of the vapor pres-sure or boiling point of the solutions is presented.The basic differential equations are derived from Gibbs-Duhem equation and can be solved easily by iterative method.This method can be successfully used forbinary systems,and in principle can also be applied to multicomponent systems.Several examples ofbinaries and ternaries are presented for demonstration.Calculated results are in good agreement with ex-perimental data.

In a previous investigation in 1963 Wang and Shen et al,found that the well known flow equationfor pulsed sieve plate column given by J.D.Thornton should be modified and written asV_s=V_d/X+V_c/(1-x)=V_0(1-x)~nThis paper is a continuation of the previous works.Four kinds of liquid-liquid system were examinedin this study.The parameters n and V_o,the Sauter mean diameter of dispersed droplets D_(3.2) arc corro-leted in terms of physical properties of the systems and operation variables.Calculated flooding veloci-ties are close to the experimental values with deviation within ±15%.

The cobalt catalyzed oxidation of cyclobexane in acetic acid solution to adipid acid by pure oxygenhas been studied.Under the following conditions of investigation:reaction temperature 80—90℃,con-centration of cyclobexane 1.08-2.97 mol/l,concentration of Co (OAC)_2·4H_2O 0.031-0.0803 mol/l,aceticacid/cyclohexane 10—20 (by weight) and oxygen pressure 5-30 kg/cm~2.,it is found that the kinetics ofadipic acid formation could be expressed by the follwoing equationr=k[C_6H_(12)][Co~(+++)]~2[Co~(++)]~(-1)[P_(o_2)]~(1/2)where r rate of formation of adipic acid;[C_6H_(12)] concentration of cyclohexane;[Co~(+++)] concentration of cobaltic ion;[Co~(++)] concentration of cobaltous ion;[P_(o_2)] pressure of oxygen;k rate constant of reaction.The temperature dependence of rate constant can be correlated with the Arrhenius equation:lnk=(-ΔE)/(RT)+AThe apparent activated energy ΔE is 32.74 kcal/g-mol.A tentative reaction mechanism is presented to explain the phenomena observed,in which the ratedetermining step is the formation of cation radical species through the interaction of Co~(+++) and cyclohex-ane molecules with Co~(+++) and Co~(++) serving as chain carriers.

An imperfect pulse injection stimulus-response technique and an on-line computer system are usedto improve the experimental and data processing technique in the study of axial mixing in the pulsed-sieve-plate extraction column.Comparison of different methods for parameter estimation proves that the“Least-squares fitting method in the time domain”is superior to the moment method and some weightedmoment methods.The uncertainty in parameter estimation is discussed.The effects of pulsation onthe axial mixing coefficient of single phase flow in the column are examined.

The exact expressions of concentration and local or average Sherwood number,Sh or Sh for non-Newtonian fluids which obey the famous power law:τ={K|1/2(1/2)~(1/2)|~(n=1)}in which the flow index n takes any positive rational value,have been obtained by solving the differen-tial equation of diffusion together with the velocity distribution in the falling film flow.The use of Fourth-order Runge-Kutta method and Wegstien’s iteration method by means of thecomputer yields results which are a series of values of dimensionless concentration O,local and averageSherwood number for n equal to 1/4,1/3,1/2,1/1.4,1/1.2,1,1.25,2.5,and ∞.When the flow indexn=1,i.e.for Newtonian fluids,the result agrees well with the data from the literature.

The mass transfer coefficient k is an important parameter for predicting the concentration polar-ization of reverse osmosis and other membrane separation processes.In order to determine the k valueprecisely,a limiting diffusion current method with specially designed porous electrode has been devel-oped.This method can be used to determine the k values for both one dimensional and two dimensionalflow.It seems that the actual situation of membrane process is closely approached,so the dimensionlessempirical equations obtained have a practical significance.The equations of present work have been compared with the data of previous authors,and manyresults seem to be in good agreements.Therefore this paper offers useful reference for the investiga-tion and design of diversified membrane separation systems in future.

Luus’ random search algorithm does not converge to the optimal solution when the selected initialvalue X~((0)) and initial search region R~((0)) are not proper.This paper has found out a reason of thefact that the above mentioned algorithm took a systematic reduction of the sizo of search region underthe constant factor.The modified random search algorithm has been proposed by the author.The idea of this al-gorithm lies in that the search region is expanded when the search is proceeding with big strides,viceversa.Thus the search region was reduced from the overall situation,but,on the contrary,it wasexpanded occasionally from the partial situation.The modified algorithm is noted as below:whether X~((0)) or R~((0)) was selected has no influence overthe reliability;it goes a way towards solving the problem of rather high dimension in theory;it issuitable not only to solving the problem of constrained nonlinear programming but also to that of un-constrained;the feasible region is not necessarily limited on convex region.The application of the modified random search algorithm was described with illustrations and thecomparison between modified and Luns’ random search algorithm has been made.

The results of adsorption equilibrium measurements show that the saturation adsorbed amounts (x/m)_Mof some organic acids increase in the following order:Acetic

The flooding point and hold-up of the dispersed phase in an extraction column with reciprocating-sieve plates of 32 mm inside diameter and 1960 mm effective column height have been investigated under thefollowing conditions:Percent perforation of the plates 40%,53.5% and 63.7%,diameters of perforatedholes 7.8,9.0 and 9.8 mm,and distances between plates 20 and 40 mm respectively.Experiments werecarried out with three different liquid-liquid systems covering a rather wide range of physical properties.The relative velocity of the two phases passing through the perforations of the plates is consideredin the present work to be related to the work done by the oscillating plates in the column on unit massof liquid in unit time.Therefore the flooding velocity and hold-up in extraction column with reci-procating sieve plates should be related to A~2F~3 instead of AF as reported before.Equations weredeveloped to correlate the experimental data of flooding point and hold-up respectively.

The mathematical model of diffusion process in polarographic determination of dissolved oxygen hasbeen thoroughly studied with an electric simulator.It is found that the combination of microelectrodeand impulse operating technique is a possible way to improve the characteristics of present Clark electrode.The quantitative relations between the electrode size and operating condition are given in this paper indimensionless form,and the range of the optimum condition has been discussed.

A modified Newton-Raphson method is presented in this paper.It consists of introducing relaxationfactor ωand parameter a into general Newton-Raphson method.Since physical variables are reasonablyupdated in a physically meaningful range at each of the iterations,they converge smoothly to a solutionto the problem.This method was examined by applying it into some examples.The results show thatthe present method was characterized by more rapid rate of convergence and better stability than eitherNewton-Raphson method or successive substitution.

A simulated occluded corrosion cell was used to study the changes within corrosion cracks or crev-ices of 1Crl8Ni9Ti austenitic stainless steel in NaCI solution.As anodic currents passed through thecell,a series of changes took place,the most important of which were pH fall and CI-migration.Itwas found that the pH fall is proportional to current density and duration of current flowing,consequentlyit is a function of the quantity of electricity passing the occluded anode.The pH in the occluded cellmight be negative value when current density was 3.5mA/cm~2 after 168 hours.Meanwhile the CI-migratedinto occluded cell increased the CI-concentration 18 times as much as the original concentration.A linear relationship existed between CI-migration in g-equivalents per cm~2 of anode area and currentdensity,and also a linear relation existed between CI-migration per hour and current intensity.Conse-quently,the number of equivalents of CI-migration into crack tip was proportional to the quantity ofelectricity passing through it.It was interesting to discover that for each faraday passed almost always1/2 g-equivalent of CI-migrated into the occluded cell.This relationship did not change whatever werethe concentration of bulk solution,current density,temperature,and time elapsed.Two empirical for-mulas regarding the relationship between pH and Cr~3+ dissolution or Cl-migration respectively werederived based on the relationships between quantity of electricity passed and other variables found in thepresent experiments.

A simulated occluded cell which can be loaded by lever system was designed to study the changesof potential and pH in it with polarization of hulk specimen for the system "lCrl8NigTi-Cl-".It wasfound that the critical stress corrosion potential lies in the same range as the corrosion potentials ofthe occluded cell.The rule of changes of potentials and pH in the occluded cell could be classifiedinto three categories:1.When the bulk specimen is polarized above the critical potential,the occluded potentials re-main nearly constant within corrosion potential range.Meanwhile,the pH in the occluded cell decreasesrapidly from 7 to 2-3.5.The stress corrosion starts and propagates because a corrosion cell of sufficientvoltage difference is established.2.When the bulk s tyecimen is polarized below the critical potential,the occluded potential alwayskeeps a few mV more positive than the bulk potential,and the pH in the occluded cell increases to higherthan bulk pH (>7).The crevice is cathodically protected.3.When the potential of bulk specimen remained in the range of the critical potential,no changeof pH and potential in the occluded cell took place.By the above relations it would be easy to evaluate occluded potential of pH from the bulk poten-tial,and one may determine whether there is danger of crevice or stress corrosion by measuring the bulkpotential.By controlling the bulk potential one could make the initiation and propagation of crevice orstress corrosion prevented.

Pseudo solid-solid reactions,which proceed through gaseous intermediates are of considerable im-portance in metallurgy,such as the reduction of metal oxides with carbon and the segregation roastingof oxidic copper or niche ores.A model for paired processes has been derived for describing in detail the reduction of ferrousoxide with carbon in various rate-controlling regimes.This model is characterized by two parameters,k_1’and k_2’which include the intrinsic chemical reaction rate constants,k_1 and k_2,the diffusion coefficientD~A_c1 and the mass transfer coefficients,h~A_m1 and h~C_2:Analytic solutions have been obtained for eight extreme cases,and a series of numerical solutiousobtained with the aid of an electronic computer are presented.A calculated example based on expcri-nental data is included at the end of the paper.