Gas-liquid phase separation

Noyes G, Microporous hydrophobic hollow fiber modules for gas-liquid phase separation in microgravity, 23rd International Conference on Environmental Systems, Colorado Springs, CO, July 12-15, 1993. 

Rescic, J., and Linse, P. Gas-liquid phase separation in charged colloidal systems. Journal of Chemical Physics, 2001, 114, No. 22, p. 10131-10136. 

The most widely used atomiser for hydride generation is the heated quartz T-tube atomiser with a typical diameter of 10 mm and a length of 100—150 mm, making it compatible with the optical path of most AA spectrometers. The quartz tube is electrically heated to 700—1000 °C which permits one to optimise the atomisation temperature for each element. The quartz tube may either have open ends, or these ends are sealed by removable quartz windows, and holes at the extreme ends of the quartz tube provide the gas flow outlets. This set-up increases the residence time of the atoms in the light path and thus improves sensitivity. With continued use the performance of the quartz tube atomiser invariably deteriorates in terms of sensitivity and precision. This is attributed both to devitrification of the inner surface of the quartz tube to a less inert modification, and to contamination of the inner atomiser surface by deposition of small particles and droplets that were not efficiently removed by the gas—liquid phase separator. 

To summarize, theory and experiment clearly demonstrate that the types of phase equilibria encountered in unmixed colloid-polymer mixtures are rather sensitive to the size ratio q. For sufficiently large ( 0.3) a colloidal gas-liquid phase separation is encountered. For 0.4, the simple model of hard spheres plus penetrable hard spheres fails to accurately describe the phase behaviour of well-defined hard-sphere eolloid plus polymer mixtures. For large -values it is essential to improve the simple description of polymer chains as penetrable hard spheres. 

The multiple phase contact inside the column is promoted by internal mass transfer equipment. Three groups of mass transfer equipment are commonly differentiated, which are separation trays, random packings and structured packings. Besides mass transfer equipment, further column internals are required in rectification to ensure the proper operation of the mass transfer equipment. Such internals may include support and hold-down plates, liquid distributors and redistributors, vapour distributor devices, gas-liquid phase separators and liquid collectors that usually do not participate on mass transfer. 

Fig. 7. Gas liquid phase separator to prevent fl-om the hit of liquid in the impulse pipes 1- column wall 2- orifice 3- separator space 4- exit pipe to the impulse pipe.

The column internals are these important imte of the apparatus idiidi are cxmstructed to ensure i oper conditions fo oi ration of die packiii Ihere are support plates, hoU-4own phrtes, liquid distributors and redistributors, gas (vapour) distributors, gas-liquid phase separators, and liquid collators. As an additional type of column internals, combined devices rinch ensuring redistribution of the phases act also as mass transfer vices. 

S, L, G curves upward and intersects the gas liquid line to form critical end points Ug and Ub. No liquid phase exits between the temperatures of and U,. The three-sided region is a region of gas-liquid phase separation. At temperatures between this region and U, the solid phase of component C] is in equilibrium with C2 rich gas phase. 

The van der Waals approach is applicable to gas-liquid phase separation in a one-component system. Another type of phase separation is observed in binary mixtures. Depending on thermodynamic conditions the components may be miscible or not. A simple model describing this is based on the following molar free enthalpy approximation... 

Fig. 6.2 Gas-liquid phase separation via Gibbs-Ensemble Monte Carlo...

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