During Coal Combustion, Hydrogen Chloride Control Mechanism

Chlorine is an element of great environmental interest and chloride is one of the pollution controlling species. Combustion of coal is a potential source .of chloride in the atmosphere and environment. The study in this paper was focused on the emission and removal of HC1 from coal burning, which was generally thought as one of key components of air pollution. The research results will be of significance for coal utilization, chloridation pollution appreciation and control.Three issues have been studied in this paper: the determination of chlorine in coal; the distribution regularities of fluorine in coals and its characteristics during coal combustion; chloride removal by blending lime with coal.The determination of chlorine in coal is a real difficult and challenging work. Combustion-hydrolysis/ion chromatography method is the most accurate, precise and successful method for the determination of chlorine in coal, the influence factors on determination of chlorine in coals by combustion-hydrolysis/ion chromatography method have been studied such as temperature, time of hydrolysis, oxygen flow rate and sample weight et al. achieved the optimal determination parameters and precision.Concentration of fluorine in typical coals from China have been determined, in order to build a national database for chlorine of all kinds of coals for the future research, and study existing forms of chlorine and the emission discipline of hydrochloric compound of raw coals. Chlorine emission characteristics during coal combustion are studied svstemically in tube furnace for the first time. The influence factors on chlorine emission and the relationship of chlorine emission with coal type, combustion temperature, retention period and combustion atmosphere are obtained and the production mechanism of gaseous chlorine during coal combustion are proposed.Experimental research and thermodynamic analysis about CaO-HCl reaction at high temperature are reported in this paper. Experimental results have identified that CaO or lime can restrain the emission of chlorine during coal combustion in fixed bed and fluidized bed. Ca/Cl or Ca/S molar ratio and combustion temperature show remarkable effect on the efficiency of chlorine removal by blending lime with coal in fluidized bed combustion. The efficiency of chlorine removal of fluidized bed combustion is superior to that of fixed bed combustion.