Black liquor char gasification with CO2 in oxy-combustion conditions

Abstract

Black liquor char from American softwood was prepared by slow and fast pyrolysis, identified as IPL and IPR, and gasified under CO/CO₂ atmospheres relevant to oxy-combustion in recovery boilers. Dynamic and isothermal experiments were used to evaluate the effects of gas composition, temperature, and char preparation on reactivity. IPR showed higher reaction rates and faster conversion than IPL, indicating that fast pyrolysis produced a more reactive char. Higher CO₂ concentration promoted gasification, while increasing temperature strongly enhanced conversion. The results provide useful kinetic data for modelling black liquor char behaviour under oxy-combustion conditions.