STUDY ON THE SCALE-UP EFFECT OF CYCLONES

The scale-up effect, which is a key factor controlling the performance of industrial cyclones, is conventionally estimated through grade efficienty curves. A new principle based on the centrifugal separation factor (CSF) is proposed to improve the scale-up procedure in designing industrial cyclones.     

EFFECT OF OPERATING TEMPERATURE AND PRESSURE ON THE TRANSITION FROM BUBBLING TO TURBULENT FLUIDIZATION

Experiments have been carried out to investigate the effects of operating temperature(50 to 500℃)andpressure(1×10~5 to 8×10~5 Pa)on the transition from bubbling to turbulent fluidization by computer analysisof the pressure fluctuation in dense phase.In order to reveal the influence of particle properties on the tran-sition process,eight kinds of particles were employed.A empirical correlaton which takes into accountthe effects of temperature and pressure is recommended for the prediction of transition velocity     

EFFECT OF DRYING METHOD ON MESOPOROSITY OF RESORCINOL–FORMALDEHYDE DRYGEL AND CARBON GEL

Resorcinol–formaldehyde hydrogels were synthesized by sol–gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution. RF cryogels, RF xerogels, and RF xerogels (MW gels) were respectively prepared from RF hydrogels by freeze drying, hot air drying, and microwave drying. Carbon cryogels, carbon xerogels and carbon MW gels were subsequently obtained by pyrolyzing RF drygels in an inert atmosphere. Freeze drying and microwave drying were effective to prepare mesoporous RF drygels and carbon gels. RF cryogels and carbon cryogels showed high mesoporosity over wide ranges of the molar ratio of resorcinol to catalyst (R/C) and the ratio of resorcinol to water (R/W) used in sol–gel polycondensation. Although RF xerogels had a few mesopores, carbon xerogels had no mesopores. RF MW gels and carbon MW gels showed mesoporosity if appropriate values of R/C and R/W were selected.     

DRYING CHARACTERISTICS OF OSMOTICALLY PRETREATED CRANBERRIES—ENERGY AND QUALITY ASPECTS*

ABSTRACT

This study reports on finish drying of osmotically pretreated (dehydrated and sugar-infused) cranberries. The halved fresh berries pretreated in a standard osmotic solution (67.5 Brix at 50°C for 5 h) were then freeze-dried, vacuum-dried and air-dried in various dryers (cabinet-air-through, fluid bed, pulsed fluid bed, and vibrated fluid bed dryers) in order to identify the best drying technology. Energy consumption and product quality were chosen as the comparison criteria. The best product quality, quantified by the anthocyanins content, rehydration ratio, color and taste, was noted for freeze-dried berries. As all other drying methods gave similar, albeit slightly lower quality products than freeze-drying, the selection of a drying method could be based on the unit heat consumption. The vibrated fluid bed and the pulsed fluid bed should be favored because of the highest energy efficiency. Even though sugar infused into cranberries during osmotic pretreatment reduces drying rates during the second drying period as compared to untreated berries, osmotic dehydration reduces the total energy consumption on top of the preferential sensory characteristics of the final product.

     

THE EFFECT OF INCLUSION COMPOUNDS ON THE PHOTOPHYSICS AND PHOTOCHEMISTRY OF SCHIFF’s BASES

通过形成希夫碱分子与环糊精或脱氧胆酸的包合化合物的方法，不仅可以使一些固态时具有热致变色性质的希夫碱表现出光致变色的性质，延长光产物的寿命，而且也可以在室温下检测到具有光致变色性质的包合化合物的荧光．     

EFFECT OF SURFACTANTS ON KINETICS OF β-CAROTENE PHOTODEGRADATION IN EMULSIONS

The effect of surfactant type on photodegradation kinetics of β-carotene in oil-in-water emulsions has been investigated. The stabilized emulsions of lecithin, sodium stearoyl 2-lactylate (SSL), and polyoxyethylene sorbitan monolaurate (Tween-20) together with a β-carotene solution in corn oil were exposed to illumination. The rate of photochemical degradation was mathematically modeled by regression fitting. The lecithin-stabilized emulsion showed higher light fastness than the other samples. β-carotene photodegradation reaction followed a zero-order kinetic model for oil-based systems and lecithin emulsions, while β-carotene degraded by a first-order reaction in SSL and Tween-20 emulsions. Thermodynamic parameters revealed that water-based samples are more heat sensitive than oil-based samples. An isokinetic relationship was observed between the samples. Moreover, results indicated mixing of SSL and Tween-20 with lecithin leads to better protection of β-carotene than emulsions stabilized with SSL or Tween-20, separately.     

EFFECT OF TEMPERATURE ON THE ADSORPTION OF METHYLENE BLUE DYE ONTO SULFURIC ACID–TREATED ORANGE PEEL

The present study explains the preparation and application of sulfuric acid–treated orange peel (STOP) as a new low-cost adsorbent in the removal of methylene blue (MB) dye from its aqueous solution. The effects of temperature on the operating parameters such as solution pH, adsorbent dose, initial MB dye concentration, and contact time were investigated for the removal of MB dye using STOP. The maximum adsorption of MB dye onto STOP took place in the following experimental conditions: pH of 8.0, adsorbent dose of 0.4 g, contact time of 45 min, and temperature of 30°C. The adsorption equilibrium data were tested by applying both the Langmuir and Freundlich isotherm models. It is observed that the Freundlich isotherm model fitted better than the Langmuir isotherm model, indicating multilayer adsorption, at all studied temperatures. The adsorption kinetic results showed that the pseudo-second-order model was more suitable to explain the adsorption of MB dye onto STOP. The adsorption mechanism results showed that the adsorption process was controlled by both the internal and external diffusion of MB dye molecules. The values of free energy change (ΔG ^o) and enthalpy change (ΔH ^o) indicated the spontaneous, feasible, and exothermic nature of the adsorption process. The maximum monolayer adsorption capacity of STOP was also compared with other low-cost adsorbents, and it was found that STOP was a better adsorbent for MB dye removal.     

EFFECT OF HEATING MODES ON INTERNAL STRAIN–STRESS FORMATION DURING DRYING OF MOLDED CERAMICS

Parametric analyses in drying processes of molded ceramics are performed to investigate the influence of heating modes on the formation of drying-induced strain–stress as well as the drying characteristic. The transient three-dimensional problem of strain–stress and heat and moisture transfer in a slab is solved simultaneously by the finite element method. Three modes of hot air, intermittent and internal heating are compared by modeling in the normalized parameters. The tensile and compressive stresses fluctuate, and fall remarkably during the low Biot number period when the slab is heated intermittently. In the internal heating mode, the drying rate is the fastest but stress formation is maintained at the lowest level among the three modes. This effectiveness of the internal heating is investigated experimentally by employing the microwave heating as well.     

EFFECT OF FIRING AT 1500°C ON THE POROSITY AND SPECIFIC GRAVITY OF QUARTZITES1

Quartzites from the various deposits being commercially utilized for the manufacture of silica brick in the United States, Canada, and Europe were tested for porosity and apparent specific gravity before and after firing at 1500 °C for 2 hours. Petrographic examination was made of several of the raw quartzites, and the differences in crystalline structure are shown by photomicrographs. The rate of conversion of the quartz. was not constant for the quartzite? reported. The porosity after firing varied from 2 to 30% and the apparent specific gravity varied from 230 to 244. A fine-grained quartzite tends to give lower porosity after firing.     

LIQUID AND SOLID PHASE REACTION KINETICS OF PHOSPHORIC ACID COMPLEX SYSTEM(Ⅱ) EXPERIMENTAL STUDY ON DIGESTION KINETICS OF PHOSPHATE ORE PARTICLE SYSTEM

(Ⅰ )报已对磷矿颗粒的扩散和反应过程进行了理论探讨 ,在系统研究金河磷矿、晓峰磷矿、开阳磷矿这3种有代表性的磷矿晶体微结构参数、物相组成等物理化学特征的基础上 ,实验研究了这些磷矿中包括杂质在内的反应动力学过程 ,并发现了铁铝杂质在反应中的负温度效应 .采用 (Ⅰ )报得到的动力学方程描述这些过程 ,获得了较满意的结果 ,分形扩散中的特殊现象和扩散中所产生的自相似结构均在实验中获得了证实     

THE EFFECT OF LIQUID PHYSICAL PROPERTIES ON DRIFT VELOCITY

Drift velocity is a very important paramcter for predictirg the pool volumetric void fraction. Two-phase system of gas and high viscous liquids pool is encountered in various engineering applications. A review of the literature shows no data for explaining the effect of highly viscous liquids on the drift velocity. This paper's analysis shows that there is a considerable influence. It is shown that the foaming behaviour of liquids is dependent on the surface properties. For some highly viscous liquids at a given superficial gas velocity, the viscosity changes with time. The effect of "foam" and "time" on drift velocity is clearly elucidated.     

A STUDY ON KINETICS OF OXIDATION OF CYCLOHEXANE TO ADIPIC ACID BY ONE-STEP PROCESS

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.     

STUDY ON THE PERFORMANCE OF VERTICAL TUBULAR LEACHING REACTOR

Hydrodynamics in vertical tubular leaching reactor was studied in this work. Based on the observation of particle saltation in curved and square return bends, the inclined return bend was developed and examined. For the narrow and wide size distribution particle system, the method for calculating the particle holdup in upflow and downflow tubes was derived on the basis of generalized fluidization equation. The model of unit pressure drop was given and examined by experiments.     

KINETICS OF METHANOL SYNTHESIS IN THE PRESENCE OF C301 Cu-BASED CATALYST (Ⅰ) INTRINSIC AND GLOBAL KINETICS

The intrinsic and global kinetics of methanol synthesis from carbon monoxide, carbon dioxide and hydrogen in the presence of C301 commercial catalyst is studied. The investigation is performed under typical commercial conditions in an isothermal plug-flow integral reactor and an     

STUDY ON THE INFLUENCE OF ANNULAR SPACE WIDTH ON THE AXIAL MIXING IN PULSED-SIEVE-PLATE EXTRACTION COLUMN

1 INTRODUCTIONAnnular pulsed-sieve-plate extraction column is an unique extraction equipment that can beused to ensure critical safety in reprocssing of irradiated nuclear fuel,The study of this kind ofextraction column has been carried out and some results were published in resent years [1—9]. It is known that axial mixing is one of most important parameters effecting column be-     

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.     

THE STUDY ON THE MASS TRANSFER MECHANISM OF EUROPIUM ION THROUGH LIQUID SURFACTANT MEMBRANES

The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forrecovering trivalent lanthanides and actinides.A layered structure model for the emulsion globule is sug-gested.The equations describing the relationship among the effective membrane thickness,the time andother factors are derived and verified experimentally.Results show that under certain conditions the decreas-ing concentration of europium ion in the external phase is proportional to the square root of the time,the acidity of the internal phase and the carrier concentration in the membrane phase.The membrane phase consists of kerosene(solvent),Span-80(surfactant)and di-(2-ethylhexyl) phosphoricacid(HDEHP,carrier).The internal phase is dilute nitric acid and the external phase is aqueous solu-tion containing Eu(NO_3)_3.The mass transfer rate of europium in this system is high and the recovery ofeuropium may be more than 99%.     

KINETICS ON EPOXIDATION OF PROPYLENE WITH ETHYLBENZENE HYDROPEROXIDE

In the range of 76° to 1200C,Dalin and others studied the kinetics on molybdenum-catalyzed epoxi-dation of propylene with ethylbenzene hydroperoxide,proposed a mechanism model of this reaction andsuggested that effective concentration of catalyst is constant during the process of epoxidation.In thispaper the reaction has been studied experimentally based on Dalin's investigation.After analyzing thedata obtained in our experiment and those of Dalin,it is shown that the effective concentration of thecatalyst is not a constant but a variable,and its rate of consumption behaves in accordance with the firstorder reaction.Thus,the authors have modified the mechanism model in literature [3] and pointed outthat the deactivation mechanism of the catalyst is different from the inhibition mechanism described byFarberof.