Removal of Alkali Vapors by a Fixed Granular-Bed Sorber Using Activated Bauxite as a Sorbent

Abstract

Studies have been conducted to develop a fixed granular-bed sorber for the removal of alkali vapors in a pressurized fluidized-bed combustion (PFBC) combinedcycle system. A laboratory-scale pressurized alkalivapor sorption test unit was used to characterize activated bauxite, the most effective sorbent identified earlier, for its alkali vapor sorption capability in a gas stream with temperature (≤900°C), pressure (10 atm absolute), and composition closely simulating the actual PFBC flue gas. A scale-up of laboratory tests is being conducted in a 15.2-cm-dia (6-in.-dia) PFBC system to demonstrate the granular-bed sorber concept. The NaCl-vapor sorption chemistry of activated bauxite is described. The extent of alkalivapor evolution from the activated bauxite bed itself is discussed, along with an evaluation of the significance of its alkali vapor contribution to a downstream gas turbine. Details of the design of a high-temperature/high-pressure alkali sorber system for the demonstration of the sorber are presented.