New Process Combining Fe-Based Chemical Looping and Biomass Pyrolysis for Cogeneration of Hydrogen, Biochar, Bio-Oil and Electricity with In-Suit CO2 Separation

Abstract

Fe-based chemical looping gasification is a clean biomass technology, which has the advantage of reducing CO2 emissions and the potential of self-sustaining operation without supplemental heating. A novel process combining Fe-based chemical looping and biomass pyrolysis was proposed and simulated using Aspen Plus. The biomass was first subjected to pyrolysis to coproduce biochar, bio-oil and pyrolysis gas; the pyrolysis gas was subjected to an Fe looping process to obtain high-purity hydrogen and carbon dioxide. The influences of the pyrolysis reactor operating temperature and fuel reactor operation temperature, and the steam reactor and air reactor on the process performance are researched. The results showed that, under the operating condition of the established process, 23.07 kg/h of bio-oil, 24.18 kg/h of biochar, 3.35 kg/h of hydrogen and a net electricity of 3 kW can be generated from 100 kg/h of rice straw, and the outlet CO2 concentration of the fuel reactor was as high as 80%. Moreover, the whole exergy efficiency and total exergy loss of the proposed process was 58.98% and 221 kW, respectively. Additionally, compared to biomass direct chemical looping hydrogen generation technology, the new process in this paper, using biomass pyrolysis gas as a reactant in the chemical looping hydrogen generation process, can enhance the efficiency of hydrogen generation.

Life Cycle Assessment of Wheat Straw Pyrolysis with Volatile Fractions Chemical Looping Combustion

“…Chemical Looping Combustion has previously been coupled with biomass pyrolysis for syngas or hydrogen production, but there are some disadvantages to direct biomass chemical looping pyrolysis, like looping material deactivation, a high solid recirculation rate, and the requirement for separation of looping materials and biomass ash [12][13][14]. For these reasons, CLC has been used to burn the volatile fractions [15] or the biochar fraction [16] in biomass pyrolysis for hydrogen or syngas production. In this study, CLC was coupled with volatile fractions with the aim of covering pyrolysis reactor thermal energy requirements, with the surplus thermal energy considered a credit.…”