Integration of biomass/steam gasification with heat recovery from hot slags: Thermodynamic characteristics

• Thermodynamics of an emerging strategy was systemically investigated herein.
• Biomass gasification was integrated with the heat recovery from hot slags.
• Optimum gasification temperatures for biomass and sludge were determined.
• Steel slags increased the H2 production and syngas HHV at low temperatures.
• Blast furnace slags showed a more prominent influence on polluted gas releases.

Herein the thermodynamics of an emerging strategy, biomass/steam gasification integrated with heat recovery from hot slags, were systematically investigated following the principle of minimum Gibbs free energy to simultaneously deal with the issues of biomass disposal in agricultural sector and heat recovery in steel industry. Not only the syngas yields but also the influence of slags were identified including blast furnace slags (BFS) and steel slags (SS). The results demonstrated that, from viewpoint of maximization of H2 production and higher heating value (HHV) of syngas, the optimum gasification temperatures for biomass and sludge were 1000 °C and 1100 °C, respectively. Compared to BFS, SS remarkably increased the H2 production and syngas HHV at lower temperatures; while for polluted gas releases including NH3, NO and NO2, BFS showed more prominent influence. The present results thus provided significant clues for syngas yield optimization and pollution mitigation toward application of this novel route.