Determination of the operating characteristics of an absorption tower

Abstract

Certain modifications in the design of an 18-inch stone-ware absorption tower, packed with 3-inch coke and located in the Unit Operations Laboratory of Virginia Polytechnic Institute, wer emade and experiments to determine the operating characteristics of the tower in the absorption of carbon dioxide by water were performed, after the changes in design were made. A distribution plate to reduce channeling, a sampling system to insure the obtaining of representative samples, and modified Orsat apparatus to permit greater accuracy of gas analyses, were designed. Channeling appeared to be somewhat reduced by the new plate and the data showed that the new sampling system obtained more representative gas sample for analysis. The modified Orsat apparatus did not appear to give more accurate gas analyses. The liquid film coefficient was calculated from data on nine experimental runs at water flow rates varying from approximately 5 to 36 pounds per minute. Temperatures of gas and water, gas flow rate, and carbon dioxide content of the flue gas were held to as limited a range of variation as possible and the data used in the calculations were taken after the tower was operating under conditions of equilibrium, as shown by the constancy of the readings. The equation, k1a = 0.0000153 (L)1.64 where k1a = liquid film absorption coefficient (lb./(hr.)(cu.ft.)(lb./cu.ft.) L = liquid flow rate (lb./(hr.)(sq.ft. tower cross section) Was derived from the experimental data. It was assumed that the relation was a power equation of the form set forth in the literature by Sherwood. No relationship between the absorption coefficients and either the gas rate of flow, temperature of the gas, temperature of the water or carbon dioxide content of the flue gas was observed.