Process Simulation of a Dual Fluidized Bed Ca-Looping Biomass Gasifier with CuO/CaO for Enhanced Hydrogen Production

In this study, H₂ production through Calcium-Looping (Ca-Looping) gasification process using biomass feedstocks, including wood waste (WW), cow manure (CM), and biocrude (BC), was investigated. This novel system employed a dual fluidized bed system, comprising a gasifier reactor with a mixture of CuO and CaO fluidized by steam, and a regenerative air reactor. Hydrogen production was investigated as a function of variations in key operating parameters, including gasification temperature (T_g), equivalence ratio (E/R), steam mass flow rate (M_steam), and CaO circulation rate (C_CaO). Enhancement in hydrogen production was not observed at temperatures above 700 °C for all feedstocks, which was confirmed to be due to the deactivation of the carbonation reaction. An increasing CO₂ volume fraction and decreasing H₂ volume fraction in the synthesis gas were observed as the E/R ratio increased. Additionally, H₂ production increased continuously with higher steam flow rate. CO₂ capturing capacity, through carbonation of CaO increased with CaO circulation rates, reaching a plateau as the circulation rate reach above 100 kg/hr. These findings highlight the potential of the biomass Ca-Looping gasification process to produce high-purity H₂ while significantly reducing CO₂ emissions, positioning it as a promising pathway for sustainable energy production.