Comparative study of process simulation, energy and exergy analyses of solar enhanced char-cycling biomass pyrolysis process.

[Display omitted] • A novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. • Solar enhanced char-cycling biomass pyrolysis process was modeled for the first time. • In SCCP process, pyrolysis has the highest exergy destruction due to no combustion. • Due to the external biochar, the SCCP process showed the highest CH 4 and CO yields. Pyrolysis is an efficient technology for converting biomass into value-added products, characterized by endothermal reactions. The introduction of induced solar irradiance can boost product yields and reduce carbon emissions associated with incineration. However, direct solar pyrolysis faces challenges due to difficulties in maintaining a clean solar window, which is essential to ensure efficient sunlight penetration. To address this issue, a novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. In this work, to demonstrate the potential of solar enhanced biomass pyrolysis process as a promising biomass treatment technology, energy and exergy analyses of Autothermal Pyrolysis (AP), Solar Direct Pyrolysis (SDP), and Solar Char-Cycling Pyrolysis (SCCP) processes were studied in Aspen Plus. The results showed that SCCP has the highest energy and exergy efficiencies, which were 90.81% and 76.51%, respectively. In comparison, the solar energy utilization efficiency of char-cycling was 82.18% due to the high radiative heat absorptivity of biochar. Meanwhile, the energy efficiencies for AP and SDP were 87.17% and 80.23 %, respectively. The lower efficiency of SDP was attributed to window contamination. When the solar adsorption efficiency of the SDP process falls below 82.18%, it leads to a lower efficiency than the SCCP process. Through the energy analysis, it was proved that in the SCCP process, solar energy could fully cover the pyrolysis energy requirement since it overcame the problem of window contamination. Through the exergy analysis, it was shown that the SCCP process has the highest exergy efficiency compared to AP and SDP, which was caused by avoiding biochar incineration and enhanced solar energy utilization. This study gives a comprehensive evaluation of biomass solar pyrolysis applications, with the char-cycling method presenting an innovative approach for the efficient utilization of solar energy. [ABSTRACT FROM AUTHOR]