Single and combined removal of HCl and alkali metal vapor from high-temperature gas by solid sorbents

The amounts of HCl and alkali metal vapor in hot gas are generally small, compared to those of sulfur compounds, nitrogen compounds, and particulates. Nevertheless, the removal of these contaminants is very beneficial in any power plant because of corrosion when they contact metal components. In this paper, the experiments by single and combined methods were carried out to remove HCl and alkali metal vapor in hot gas cleaning. The results indicated that all sorbents for the removal of HCl vapor can reduce HCl to less than 1 mg/m³ at 550 °C; sorbent E1 self-prepared by montmorillonite and Mg(OH)₂ presents the highest chlorine content and the longest breakthrough time. It is found that the activated Al₂O₃ having a specific surface area of 258.3 m²/g displays the highest efficiency for the removal of alkali metal vapor at 840 °C. The tests indicate that the removal of alkali metal vapor with activated Al₂O₃ is not a physical adsorption process in the presence of moisture. A multifunctional four-zone reactor system was developed for the combined removal of HCl and alkali metal vapor, and the results show that the removal of HCl and alkali metal vapor with high efficiency is feasible by solid sorbents in a reactor.