The effect of varying the sieve tray perforation size on liquid-phase controlled absorption.

Abstract

A pilot plant sieve plate absorption column was used to study the effect of varying the perforation size in liquid phase controlled absorption. Four separate test trays were utilized which had hole diameters of 0.125, 0.250, 0.500, and 1.000 inches but which, at the same time had equal total gas flow areas. The gas-liquid systems used were carbon dioxide with water and carbon dioxide with aqueous glycol solution. Test runs were performed at 77°F. and at a pressure of approximately 830 mm. of mercury. Liquid flow rates ranged from 0.1 to 4.0 gpm. while gas flow rates ranged from 0.0 to 1.0 cu. ft./sec.. Experiments included the measurement of dry plate pressure drops, wet plate pressure drops, clear liquid depths and froth heights, the determination of Murphree liquid efficiencies, and also the determination of concentration profiles within the liquid froth for carbon dioxide and water. The Murphree liquid efficiencies were found to be almost independent of the hole diameter, and unexpectedly almost independent of liquid flow rates and also of gas flow rates. That is, the Murphree liquid efficiency was found to be approximately constant (70-90 percent). Murphree liquid efficiencies were found to be dependent on liquid viscosity and solute gas diffusivity. The wet plate pressure drops and depths of clear liquid were both found to be almost independent of hole diameter. The froth heights were found to be somewhat dependent on the hole diameter, smaller holes yielding greater froth heights. The concentration profiles showed that the major concentration gradient of the liquid in the froth occurred in the region below the weir height. From the results obtained by the integration of the concentration profiles, it was concluded that the mixing of the liquid on the tray could be adequately described by the "plug flow" mixing model.