(2010) Chemosphere_An investigation into the impact of CO₂ co-feed on pyrolysis and gasification

Kwon E., Kim S.

() Chemosphere ISSN: 456535 Vol.80 Issue.8 DOI: 10.1016/j.chemosphere.2010.04.068

This paper presents experimental results of the impact of CO₂ co-feed on a gasification/pyrolysis process for various feedstocks (biomass, coal, and municipal solid waste (MSW)). Various feedstocks were thermo-gravimetrically characterized under various atmospheric conditions and heating rates. A substantial amount of char burn out was identified in the presence of CO₂ via a series of thermo-gravimetric analysis tests, which enabled high conversion of final mass (∼99%) to be achieved. The impact of CO₂ co-feed on the volatilization regime during the pyrolysis/gasification process was not apparent at a heating rate of 10-40°C min^-1. However, the impact of CO₂ on the volatilization regime at a fast heating rate (950°C min^-1) was substantial. For example, significant enhancement in the generation of CO, by a factor of ∼2, was observed in the presence of CO₂. The generation of major chemical species, such as CH₄ and C₂H₄, were enhanced, but this was not as apparent as in the case with CO. In addition, introducing CO₂ to the pyrolysis/gasification process enabled the amount of condensable liquid hydrocarbons, such as tar (∼30-40%) to be significantly reduced in the presence of CO₂, in that injecting CO₂ into the pyrolysis/gasification process expedites cracking the volatilized chemical species. Experimental work confirmed that biomass and MSW could be feasible and desirable feedstocks for the pyrolysis/gasification process as these feedstocks can be easily treated compared to coal. To extend this understanding to a more practical level, various feedstocks were tested in a tubular reactor and drop tube reactor under various experimental conditions. © 2010 Elsevier Ltd.