Experimental Study Of HCl Real-time Emission Characteristics In The Co-combustion Of Coal And Simulated Municipal Solid Wastes

The rapidly increasing municipal solid wastes (MSW) production, the scarcity of landfill sites and constantly growing disposal costs have hastened efforts to adopt MSW combustion technologies. However, the public is concerned primarily about the potential emissions of toxic compounds during such MSW incineration process. Hydrogen chloride emitted from incinerators results primarily from the decomposition of various chlorides and from reactions with hydrogen resources in MSW, which respectively contributes most of organic and inorganic chlorides for HC1 formation. Therefore, it is necessary to study the secondary pollution problem in MSW incineration process.According to the composition of municipal solid waste, simulated municipal solid wastes (SMSW) were prepared and used in the tests. The physical and chemical characteristics, especially the chloride content of MSW were analysized. which enriches the database of the characteristics of MSW and provides the theoretical and data basis to the studies of solid waste in the future.The chlorine content of SMSW was regulated by adding different content of organic chloride(PVC) and inorganic chloride(NaCl), and a lab-scale tube furnace was applied to investigate the emission characteristics of HC1 during SMSW incineration and the compound of SMSW and coal incineration. The gaseous HC1 emission was measured by Fourier transform infrared spectrometer(FTIR) and the impact of temperature, the source of chlorine, the chlorine content and the ratio of coal and SMSW to the HC1 concentration were investigated.Results indicate that compared to the combustion of SMSW with NaCl, the HC1 concentration is relatively higher in the incineration of SMSW with PVC. With the chlorine content increasing, the HC1 absorption from SMSW combustion with PVC quickly increases. However, there is no significant change in the case of SMSW incineration with NaCl. The HC1 release beginning temperature in the incineration of SMSW with PVC is around 250℃and the maximum concentration value of HC1 occurs at 300℃. Gaseous HC1 emission can be detected above 900℃in SMSW incineration with NaCl. With R value (the ratio of coal and SMSW including organic chloride PVC, inorganic chloride NaCl) increasing, the chlorine content of mixtures decreases, which shows the chlorine source of mixtures mostly comes from SMSW and addition of PVC, NaCl. Correspondingly, the maximum concentration value of HC1 decreases and the releasing area becomes larger when the mixtures of coal and SMSW with PVC, which explains that the addition of coal leads to lower HC1 emissions. However, the maximum concentration value of HC1 increases with the amount of coal in the incineration of the mixtures of coal and SMSW with NaCl. Whether adding organic or inorganic chloride, the conversion of C1-HC1 increases.Two samples of MSW including NaCl were burning under 750℃and 850℃for 1 hour respectively. Then the ash after incinerating was analyzed by means of EDX, XRD and SEM. The chemical thermodynamics balance simulation software FACTSage was used to simulate the compositon of the production and the developing trend with temperature under a given initial condition. The facts suggest that potential for HCl formation show a close relationship between the experimental results and the model prediction.