Study on the conversion of CaCl2 with H2O and CO2 for dechlorinating pyrolysis of municipal solid waste

Abstract

In a pyrolysis-combustion combined process for treatment of municipal solid waste (MSW), the removal of HCl from the volatile before combustion, with a calcium-based absorbent has been broadly investigated, but the conversion of CaCl2 as the reverse reaction of the absorption of HCl has seldom been reported. In this work, the conversion of CaCl2 with H2O and CO2 (main products from pyrolysis of MSW) in the temperature range of 350 °C-650 °C is studied by fixed-bed experiments and thermodynamic analysis. The results show that the conversion of CaCl2 increases with the increase of temperature and with the increasing contents of CO2 and H2O. Comparatively, the impacts of CO2 and H2O are both stronger in lower temperatures, and the influence of H2O is more distinct than that of CO2. The existence of H2O is a prerequisite for the conversion of CaCl2, and the component of CO2 is promotive to the reaction of CaCl2.