An Experimental Investigation of Alkali Removal from Biomass Producer Gas Using a Fixed Bed of Solid Sorbent

A bench-scale gasifier system composed of a fluidized-bed gasifier, high-temperature ceramic filter, and fixed-bed solid sorbent reactor was used to study the removal of alkali from a hot product gas stream. During a test conducted with an empty solid sorbent reactor, dry gas-phase concentrations of 28 ppmw K, 11 ppmw Na, and 1309 ppmw Cl were measured. Four subsequent tests utilized 2.4−3.4-mm-diameter particles of activated bauxite or emathlite in the solid sorbent reactor. Over these four tests, K concentrations ranged from 0.03 to 0.07 ppmw, and Na concentrations ranged from 0.2 and 0.9 ppmw at the exit of the solid sorbent reactor. Chlorine concentrations at the exit of the reactor were essentially unaffected. Hot-water leaching tests indicated that alkali capture by activated bauxite and emathlite was through physical adsorption and chemisorption, respectively.