High Temperature Removal of Alkali and Particulates in Pressurized Gasification Systems

Abstract

Extensive thermodynamic and preliminary experimental studies have identified the potential use of aluminosilicate materials to simultaneously remove volatile alkali and particulate released during pressurized gasification of coal. The gettering capacity of three selected materials have been evaluated in a bench-scale reactor operating at 1114 kPa total pressure and 1123–1173K in alkali-laden inert, and simulated fuel gas environments. At 1123 K, alkali gettering has been established to result through reaction within the amorphous acid-insoluble alumino-silicate fraction of these materials, while at 1173 K saturation of the insoluble matrix is achieved, with gettering occurring mainly through acid-soluble complexes. The gettering mechanism as either a chemical reaction or a physical adsorption phenomenon and reaction kinetics will be delineated through future thermogravimetric (TG) analyses.

Control of alkali species in gasification systems: Final report

“…Thermogravimetric methods were used to study the effects of carrier gas flowrate, 16 alkali concentration in the carrier gas, 16 carrier gas species composition, 19,20 sorbent temperature, 16,19,22 sorbent particle size, 16 and elapsed time [19][20][21][22] on the capture of alkali species, and to obtain data suitable for modeling the rate kinetics of single particle alkali sorption. 16,[19][20][21][22] Packed bed investigations were used to study the effects of sorbent temperature, 14,23 superficial gas velocity, 14 space velocity, 14 carrier gas moisture content, 17 partial pressure 17 of SO 2 , and carrier gas composition. 23 In most cases, pure alkali or an alkali compound was vaporized in a hot gas stream that was directed over a sample of the sorbent.…”

“…16,[19][20][21][22] Packed bed investigations were used to study the effects of sorbent temperature, 14,23 superficial gas velocity, 14 space velocity, 14 carrier gas moisture content, 17 partial pressure 17 of SO 2 , and carrier gas composition. 23 In most cases, pure alkali or an alkali compound was vaporized in a hot gas stream that was directed over a sample of the sorbent. The gas streams varied in origin and composition and included simulated flue gas (SFG) mixtures, 14,17,21,22 inert gases, 16,19,23 simulated producer gas, 23 methanol combustion products, 19 and air.…”

“…23 In most cases, pure alkali or an alkali compound was vaporized in a hot gas stream that was directed over a sample of the sorbent. The gas streams varied in origin and composition and included simulated flue gas (SFG) mixtures, 14,17,21,22 inert gases, 16,19,23 simulated producer gas, 23 methanol combustion products, 19 and air. 18 Packed beds were also used to study the release of alkali from as-received and regenerated getter materials, and the displacement of alkali inherent in the getter material by alkali from the gas stream.…”

“…Tests were performed exposing kaolin samples to 80 ppmv NaCl in various carrier gases at 850°a nd 900°C, 11 bar pressure for 4 h. 23 The study included three carrier gases: (1) argon, (2) 10% H 2 with balance N 2 , and (3) a synthetic fuel gas composed of 7.5% CO 2 , 23% CO, 14% H 2 , 55% N 2 , and the balance composed of H 2 S and HCl. Surprisingly, the synthetic fuel gas contained no water vapor.…”

“…Getter beds were to be employed to simultaneously remove particulate and vapor-phase alkali. Gasifier combined cycle applications 19,23 were explored to a lesser extent and always in the context of using coal as the fuel source. In all the research, Na removal received greater emphasis than K removal.…”