Experimental study on coal-fired flue gas HCl removal by injecting adsorbent into flue duct

Abstract Adsorbent injection into flue ducts is an effective technology for controlling gaseous pollutant in coal-fired power plants. This study proposed a new technique of injecting dechlorinater into flue duct for HCl removal in order to realize the wet flue gas desulfurization (WFGD) wastewater sequestration and upgrade the gypsum quality, known as the source dechlorination method. Four alkaline-based adsorbents of CaO, Ca(OH) 2 + 5 % NaOH, ethanol-modified CaO, and NaHCO 3 were developed and investigated in a pilot scale 6 kW coal-fired circulating fluidized bed (CFB) combustion system for capturing flue gas HCl. The physical and chemical properties of the adsorbents were characterized to explore the reaction mechanisms affected by the adsorbent size and its distribution, active component loading, micro-structure, morphology, and crystal structure. The influences of the injection amount, resident time and flue gas temperature on the HCl removal efficiency were carried out, the dechlorination mechanism of the ethanol-modified CaO were discussed. The distribution of flue gas chlorine species across the air pollutant control devices (APCD) were obtained. This study provides basis for developing the technology of injecting dechlorinater into flue gas for HCl removal.