Combustion, pyrolysis and char CO2-gasification characteristics of hydrothermal carbonization solid fuel from municipal solid wastes

• Combustion, pyrolysis and char CO2-gasification of hydrochar from MSW were evaluated.
• Study on char CO2-gasification behavior of MSW hydrochar was novel.
• Effects of HTC temperature and residence time were investigated.
• HTC treatment exerted significant effects on the thermal behavior.
• Thermal process kinetic parameters were determined by Arrhenius analysis.

Hydrothermal carbonization (HTC) is a promising pretreatment for converting wet biomass waste into a solid fuel. In this paper, the resource utilization of municipal solid wastes (MSW) for energy purposes was studied. Experiments were employed at several temperatures (210, 230, 250 and 280 °C) and residence times (30, 60 and 90 min) to investigate the effects on the combustion, pyrolysis and char CO2-gasification characteristics of hydrothermal carbonization solid fuel from MSW. The results of thermogravimetric analysis illustrated that HTC did remarkable influences on the thermal behavior and kinetics of MSW. In most cases, the HTC temperature had more obvious effect than residence time. It proved the potential of HTC as a sufficient way to provide a more suitable feedstock for further thermochemical conversion processes as it improved the thermal performance of MSW. These findings suggested combining hydrothermal carbonization upgrading treatment with subsequent thermochemical process could be a soundly positive way for both energy generation and waste remediation. The kinetics parameters of thermal process were obtained by the Coats−Redfern model, which could contribute to getting knowledge on the reaction mechanisms of hydrochars. These experimental results help to understand and predict the behavior of hydrochars from HTC of MSW and hydrothermal disposal of MSW in practical applications.