THEORETICAL AND EXPERIMENTAL STUDIES ON BUBBLE DIAMETER AND GAS HOLDUP IN AERATED STIRRED TANKS

1 INTRODUCTIONBubble diameter distribution and gas holdup are very important parameters indicatingthe characteristics of gas-liquid dispersion,works done are mostly experimentalobservation.Theoretical analysis of bubble diameter has been mostly focused on thebreak-up of bubbles in the impeller region,and only the theoretical relationship be-tween bubble diameter and operating variables in the impeller region has been reported     

STUDY ON EBULLIOMETRIC METHOD AND LEANING EBULLIOMETER

The relation between the gravimetric liquid concentration (χ_(10)) and equilibrium one (χ_1) is developed for the system within an ebulliometer or a still operating steadily. From the relation, the necessary and sufficient condition for χ_(10)→χ_1, and a new equation for calculating limiting activity coefficient (γ~∞) are deduced. This equation proves more accurate than that proposed by previous researchers. The leaning ebulliometer, a new apparatus, is designed to measure bubble points and γ~∞ without composition analysis, its operating line (T, P, χ_(10)) proves a good approximation to the bubble-point line (T, P, χ_1): |(χ_(10)-χ_1)/χ)|<0.005|K_1-1|, where K_1=y_1/χ_1 is the K-value.     

A STUDY ON HEAT TRANSFER IN INCLINED REFLUX CONDENSERS

The condensation heat transfer in the inclined reflux condensers is investigated at various inclinations. A condensation heat transfer model is set up. The calculated values of the model agree well with the experimental data. Both the experimental data and the theoretical calculations show that the condensation heat transfer coefficient in the inclined reflux condensers varies with the inclinations and will be maximum when the inclination angle is about 10°.     

A STUDY ON FLOODING VELOCITIES IN INCLINED REFLUX CONDENSERS

This paper deals with the flooding velocities of the reflux condensers with various inclinations.The flooding phenomena and two-phase flow patterns in such condensers have been observed. A physical and a mathematical models for calculating flooding velocities are developed, which agree well with the experimental data. The flooding velocity in an inclined reflux condenser varies with the inclination and may reach the maximum value when the inclination is between 30° and 50°.     

EXPERIMENTAL INVESTIGATION ON GAS HYDRATE FORMATION IN PRESENCE OF ADDITIVE COMPONENTS

Additives were used to increase gas hydrate formation rate and storage capacity. Experimental tests of methane hydrate formation were carried out in surfactant water solutions in a high-pressure cell. Sodium dodecyl sulfate (SDS) and alkyl polysaccharide glycoside (APG) were used to increase hydrate formation. The effect of SDS on hydrate formation is more pronounced compared APG. Cyclopentane (CP) also improves hydrate formation rates while it cannot increase methane gas storage capacity.     

A STUDY ON MASS TRANSFER IN PULSED SIEVE-PLATE EXTRACTION COLUMN

Mass transfer experiments have been carried out in a 40mm diameter pulsed sieve-plate extraction column. Both standard and "dispersion-coalescence" type cartridges were tested with 30％ TBP (kerosene as diluent)/ Nitric Acid/Water system. "Ture" volumetric mass transfer coefficient and backmixing     

STUDY ON RED-SENSITIZED PHOTO-POLYMER SYSTEM FOR HOLOGRAPHY AND ITS PROPERTIES

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FLOW REGIME TRANSITIONS IN GAS-LIQUID JET-PUMP REACTOR

It is found that the reactor has four types of flow regimes:a,b,c,and d,of which b is desirable inoperation.Therefore it is essential to find the criteria for flow regime transitions.On the basis of momen-tum,energy and mass balance principles,theoretical criteria are obtained and agree well with the experi-mental results,which can be expressed ascri1     

HYDRODYNAMICS AND GAS-LIQUID-SOLID INTERFACIAL PARAMETERS OF CO-CURRENT DOWNWARD TWO-PHASE FLOW IN TRICKLE-BED REACTORS†

Design of trickle-fixed bed reactors requires knowledge of the hydrodynamics of two-phase co-current downward flow through fixed porous catalytic media and interfacial parameters. Unfortunately, most of the published papers deal exclusively with the hydrodynamics of an air-water system and the determination of gas-liquid-solid interfacial parameters in highly ionic solutions. In this paper, we present some experimental results on the hydrodynamics, pressure drop, liquid holdup, different flow patterns, gas-liquid interfacial areas and liquid-side mass transfer coefficients for organic non-viscous and viscous liquids and liquid-solid mass transfer coefficients with different packings: glass beads (d_p = 1.16 × 10^?3 m and 4 × 10^?3 m), spherical catalyst (d_p = 2.4 × 10^?3 m) and glass Raschig rings (d_p = 6.48 × 10^?3 m). Comparison between our values and correlations in the literature will be discussed.     

ON THE STUDY OF TIME-VARYING TEMPERATURE DRYING—EFFECT ON DRYING KINETICS AND PRODUCT QUALITY

ABSTRACT

The ability of heat pump dryer to produce controlled transient drying conditions, in terms of temperature, humidity and air velocity, has given it an edge over other drying systems. Exploiting this characteristic, we studied and compared the effect of different temperature-time profiles on the quality of agricultural products in a tunnel heat pump dryer capable of providing up to 14.6 kW of cooling capacity. The product quality refers to the color change of the products. Samples of banana and guava were dried in batches in a two-stage heat pump dryer. The effects of the starting temperature of a selected profile and the cycle time on both drying kinetics and product quality were studied. It was observed that by employing a step change in drying air temperature with the appropriate starting temperature and cycle time, it was possible to reduce significantly the drying time to reach the desired moisture content with improved product color.     

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-     

HYDROGEN BONDING IN AGGREGATES OF DIALKYL-SUBSTITUTED DLPHOSPHONIC ACIDS AND MONOFUNCTIONAL ANALOGUES∗

ABSTRACT

Hydrogen bonding of dialkyl-substituted diphosphonic acids in nonpolar (toluene and CC1₄) and alcohol (1-decanol) solutions is examined. The compounds are monomeric in 1-decanol and dimeric or higher in nonpolar organic diluents. Infrared spectroscopy and molecular mechanics calculations suggest that the dimers of P,P'-di(2-ethylhexyl) methanediphosphonic acid (H₂DEH[MDP]) and its straight-chain isomer, P.P'-dioctyl methanediphosphonic acid (H₂DO[MDP]), adopt rigid highly hydrogen-bonded structures such as C or D. The homologous P.P'-di(2-ethylhexyl) ethane- and butanediphosphonic acids, H₂DEH[EDP] and H₂DEH[BuDP], respectively, adopt structures that are also intermolecularly hydrogen-bonded but more flexible. The effect on the P=0 stretching vibration of increasing 1-decanol concentration in the solvent differs for these compounds. In the case of H₂DEH[MDP]and H₂DO[MDP], the frequency remains constant until all CC1₄ has been replaced by the alcohol, then the P=0 stretching frequency shifts to a lower energy. In the case of H₂DEH[EDP] and H₂DEH[BuDP], a gradual shift to higher energy occurs as the alcohol concentration increases. The magnitude of the difference in the P=0     

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     

STUDY ON THE ELECTROCHEMICAL BEHAVIOR OF ION EXCHANGE MEMBRANE IN PREPARING POTASSIUM CARBONATE

This investigation describes the one step preparation of potassium carbonate by electrolysis of potas-sium chloride solution in electrolyzers with various Nation membranes.Potassium bicarbonate solution wasfed to the cathode compartment,where it was converted into carbonate by reaction with the hydroxideformed at cathode.Because of the low OH~- concentration in the cathode compartment,the back migrationof OH~- through the membrane was almost negligible,resulting in a higher current efficiency,say 90% or more.In this study,electroconductivity,mass transfer,current efficiency and cell voltage were measured.Thefeasibility of the process was discussed and the optimal conditions examined.     

HYSTERESIS OF GAS-LIQUID MASS TRANSFER IN A TRICKLE BED REACTOR

1 INTRODUCTIONTrickle bed reactors are widely used in the process industry,particularly in petroleumhydroprocessing operations,and have been extensively studied by chemical engineers.In atrickle bed reactor,the gas and liquid flow cocurrently down through the packed bedand undergo chemical reactions.However,there exist multiple hydrodynamic stateswhich correspond to either uniform or,in most cases,nonuniform radial distributionof the gas and liquid flows in the packed section.Moreover,the hydrodynamic state is     

A PRELIMINARY STUDY ON LIQUID MEMBRANE SEPARATION IN ROTATING DISK CONTACTORS WITH PERFORATED DISKS

A rotating disk contactor (RDC) with perforated disks was employed for liquid membrane separation. Hydrodynamic characteristics and rate of mass transfer in the contactor were studied. Experimental results indicated that the rotating perforated disks contributed tremendously to liquid-liquid dispersion as well as to the rate of mass transfer. It is claimed, therefore, that contactors equiped with perforated disks is well adaptable to the continuous processing of liquid membrane separations     

STUDY ON LIQUID PHASE MIXING IN PACKED COLUMN (Ⅰ) A PSEUDO-ONE-DIMENSIONAL MODEL

A pseudo-one-dimensional model comprising different coaxial mixing is proposed for the study of the liquid phase mixing in packed column. The model parameters are estimated by the optimal method of nonlinear programming, and the equivalent mixing coefficient is regressed in the form of dimensionless equation.     

A STUDY ON TWO-PHASE FLOW CHARACTERISTICS IN PULSED SIEVE PLATE COLUMN FOR LIQUID-LIQUID EXTRACTION

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%.     

A STUDY ON THE SCALING RATE MODEL OF CALCIUM CARBONATE IN SATURATED WATER SYSTEM

1 INTRODUCTIONCalcium carbonate scaling is quite common in chemical processes,especially in heatexchangers.Only limited work has been done in mathematical modelling describingthe calcium carbonate scaling phenomenon.Hasson’s ionic diffusion model happenedto be one being rather broadly accepted.     

STUDY ON LIQUID PHASE MIXING IN PACKED COLUMN (Ⅱ) A TWO-DIMENSIONAL MODEL

A two-dimensional model involving both radial and axial mixing under the condition of steady tracer injection from a point source is presented. The model parameters are estimated by the optimal method of nonlinear programming, using the two-dimensional RTD experimental data obtaincd in a 1m diameter packed column. Dimensionless equations for the evaluation of axial and radial Peeler numbers are regressed.