Removal of Gaseous Alkali Metal Compounds from Hot Flue Gas by Particulate Sorbents

Six commercially available materials have been tested as granular sorbents to be used in granular-bed filters for the removal of gaseous alkali metal compounds from the hot (1073 to 1153 K) flue gas of pressurized fluidized-bed combustors (PFBC) for proposed combined-cycle power generation. Tests were performed using a simulated dry flue gas of PFBC in a laboratory-scale, fixed-bed combustor. Diatomaceous earth and activated bauxite were found to be the two most promising sorbents. The experimental results of screening tests are presented, along with the effects of temperature and superficial velocity and space velocity of the flue gas on the sorption performance for the two sorbents. Possible sorption mechanisms, applications of the sorbents and preliminary cost evaluations are discussed.