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-This work presents aspects of the parastillation process, which employs a unique distillation column where the vapor stream is divided into two equal parts and the falling liquid is alternately in contact with both vapor parts on a stage-by-stage basis. A laboratory-scale apparatus was used to study the parastillation column. Experiments were carried out under total and partial reflux conditions using an ethanolwater system. Experiments were conducted to analyze the effects of vapor flow rate and initial ethanol concentration in the reboiler on the hydrodynamic conditions. Limiting operating conditions were defined. Murphree separation efficiencies were calculated and discussed.

-The purpose of this work was to study the mass transfer performance of rotating packed beds applying the "Higee" process. The operations were carried out with the n-hexane/n-heptane distilling system at atmospheric pressure and under total reflux conditions. The rotating speed could be varied between 300 and 2500 rpm, which provided centrifugal forces from 5 to 316 times the Earth's gravity. The effects of concentration, vapor velocity, rotating speed and packing type (two different Raschig ring sizes and structured wire mesh packing) on mass transfer behavior were analyzed. Experimental results showed that the mass transfer coefficient depends on the liquid flow rates and rotating speed. The equipment had high separation efficiency in a reduced bed volume.

This paper investigates some aspects of the parastillation process, which employs a unique distillation column. A laboratory scale apparatus was used to study the parastillation column. Experiments were carried out under total and partial reflux conditions, using an ethanol‐water system. Experiments were conducted to analyze the influence of the vapour flow rate and reboiler initial ethanol concentration on the hydrodynamic conditions. Limiting operating conditions were defined. Murphree separation efficiencies were calculated and discussed.

istillation is an energy-intensive operation and any increase in separation efficiency leads to a sharp reduction in operational costs. D Trays without downcomers or dual-flow trays have several advantages over conventional trays. These trays have a greater capacity and lower pressure drop than trays with downcomers. In addition, dual-flow trays are the only device suitable for services with fouling or dirt. A considerable amount of basic experimental work has been carried out on the hydrodynamic behaviour of this type of tray. In contrast, studies on mass transfer are sparse. However, all the work shows the high sensitivity of operational parameters to physical properties, in particular the surface tension gradient.Experimental observations in several studies on the hydrodynamic behaviour of distillation co~umns using perforated trays without downcomers (Fane and Sawistowski, 1968;Mahendru and Hackl, 1979; Ravagnani et al., 1990) show that neutral and negative systems, according to Zuiderweg and Harmens (1 958) classification, have large bubbles and gas jets, which means a significant decrease in separation efficiency.Solid particles are added in many gas-liquid operations in order to improve the mass transfer rate. In these operations, the particles are fluidized by the fluids and the resulting operations are called three-phase fluidization operations. Their main application has been the solid catalytic reactions where gases and liquids are involved. In general, particles can also be added to the vapour-liquid dispersion formed on distillation trays without downcomers to improve the separation efficiency of the negative and neutral systems or be applied as a catalyst in catalytic distillation. Efficiency on plates without downcomers can also be increased by diminishing the diameter of the holes at the cost of an increase in pressure drop and a decrease in the range of stable operations. However, independent of hole size, negative and neutral systems have big bubbles and jets in their dispersions, and the particles may break these bubbles and jets into small ones or even prevent their formation, thus increasing the separation efficiency. The developed liquid-solid-vapour dispersion can be characterized as a three-phase fluidized bed. Thus, studies (Ostergaard, 1971; Fan, 1989) show that the addition of particles in some operations, such as absorption and/or reaction using bubbling columns, can increase the mass transfer rate, depending on the size, wettability and amount of the particles.In the present work, the hydrodynamic and mass transfer behaviours of a three-phase distillation column using the ethanol-n-butanol system are studied. The effects of mount, size and type of particles on the vapour phase Murphree efficiency is analyzed under several operating conditions.Separation efficiency in distillation operations can be improved by modifying the characteristics of the dispersions formed on the trays. The present work reports on the hydrodynamic and mass transfer characteristics of liquid-solid-vapour dis...

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