Release of HCl and H₂S during pyrolysis of aged refuse derived-fuels

Based on the horizontal tubular reactor-chemical absorption together with TG-FTIR-MS methods, release characteristics of corrosive gases, viz., HCl and H₂S, during pyrolysis of refuse derived-fuels were investigated. The effects of pyrolysis temperature and pyrolysis type on their release behaviors for the aged (ARDF) and normal (NRDF) categories were compared. Meanwhile, the occurrence properties of corrosive elements (Cl and S) in solid products were also explored. The results indicate that the release of each corrosive gas has similar characteristic temperature range for slow pyrolysis of two categories. The release of HCl occurs at 200-400 and 420-500℃, respectively, while the emission of H₂S is observed at 230-370 and 380-670℃, respectively. In addition, ARDF has a lower emission amounts of both HCl and H₂S compared to NRDF under this condition. With regard to fast pyrolysis, the release of corrosive gases show different regularities, which largely depends on pyrolysis temperature. With increasing temperature, the emission of HCl and H₂S present a nonlinear and an increasing trends, respectively, reaching peak values at 850℃; It is 48.8% (ARDF) and 29.4% (NRDF) for HCl, 6.8% (ARDF) and 44.6% (NRDF) for H₂S. Subsequently, due to the distinctive release characteristics of corrosive gases, the occurrence of corrosive elements in solid phase relating to temperature differs in two categories. The retained amounts of Cl and S reach to 59.4% (450℃) and 84.3% (750℃) for ARDF, respectively. But for NRDF, that is 36.7% (850℃) and 15.2% (650℃), repetitively. It can be inferred that ARDF has the more stable corrosive elements difficult to be released into gases, which could provide some guidelines on thermal utilization of refuse derived-fuels.