Kinetic studies of dry sorbents for medium temperature application. Final report, September 1, 1993--August 31, 1994

Abstract

The purpose of this project is to study the fundamental nature of the sorbent reactivity and reaction kinetics in the medium temperature range from 600{degrees}F to 1200{degrees}F available in the convective pass of a boiler upstream of the economizer, where dry sorbents are injected to remove SO{sub 2} from the flue gas. Research focus is on the fundamental mechanisms of sorbent-flue gas interaction under economizer and hot baghouse conditions utilizing the experimental setup and the results of the first three years of research. During the fourth year, the interference of carbonation reaction to sulfation reaction was studied as well as the concentration dependency of the sulfation reaction. The data to date showed that the carbonation did not interfere the sulfation reaction rate for reactions taking place less than 1 second. However, there was significant decrease in carbonation conversion when the sulfation reaction took place simultaneously. The levels of SO{sub 2} concentration had negligible effects on reaction rates when the concentration was maintained above 3000 ppM. An n-th order deactivation kinetic model was also developed during the fourth year to model the kinetics of various reactions. This model is particularly useful for the dry sorbent reactions, since the apparent rate constants rapidly decrease during the first 1 second of exposure to various gaseous reactants.