Performance Evaluation of Torrefaction Coupled with a Chemical Looping Gasification Process under Autothermal Conditions: Flexible Syngas Production from Biomass

Abstract

Herein, a coupled biomass torrefaction and chemical looping gasification (BTCLG) process was proposed, and process simulations were performed under autothermal conditions. The effects of operational parameters on product distribution with torrefaction temperatures from 240 to 300 °C, gasification temperatures from 700 to 880 °C, and steam/biomass (S/B) ratios from 0.5 to 1.5 were explored. The results showed that the process could stably operate under autothermal conditions. Torrefaction increased the syngas yield, heating value, and cold gas efficiency by 12.44, 5.11, and 36.73%, respectively. Moreover, it reduced the bed material circulation rate required for autothermal operation by 59.03%. At the torrefaction temperature of 240 °C, the syngas yield reached a maximum value of 0.78 Nm 3 /kg. Increases in the gasification temperature also positively impacted syngas production. However, the optimal gasification temperature was 810 °C based on the bed material circulation rate constraint. The syngas H 2 /CO ratio could be flexibly adjusted from 1.62 to 3.34 by changing the S/B ratio to meet downstream demands. Overall, the simulation results support the technical viability and demonstrate the excellent performance of the BTCLG process compared to the biomass CLG process.

Carbon‐negative syngas production: A comprehensive assessment of biomass pyrolysis coupling chemical looping reforming

“…Figure 9 displays the syngas products of various processes, depicting syngas yield, syngas purity, and syngas HHV, respectively. To facilitate comprehensive comparison of different processes, we compared the results of previous studies, including the autothermal biomass torrefaction and chemical looping gasification (BTCLG) process by Gen Liu et al, 14 the autothermal coal chemical looping gasification (CCLG) process by et al, 73 and the unautothermal 25 kWth biomass gasification using chemical looping (BGCL) experiment by Huijun Ge et al 74 As demonstrated in Figure 9A, the CCLG process exhibits the highest syngas yield of 1.52 Nm 3 /kg coal, whereas SG process shows the lowest yield of 0.61 Nm 3 /kg biomass. CCLG's higher syngas yield is attributed to the higher heating value of coal.…”

“…12,13 Chemical looping gasification (CLG) has emerged as a promising gasification technology, garnering significant attention from researchers. 14,15 A schematic of a typical CLG process is illustrated in Figure 1, where two interconnected fluidized bed reactors serve as an air reactor (AR) and a fuel reactor (FR). The fuel is mixed with an oxygen carrier that provides the necessary lattice oxygen for fuel gasification in the FR.…”

Thermodynamic Analysis of Optimal Performance of Three Modes of Operation of Autothermal Chemical Looping Gasification

“…Exergy analysis revealed that the major destruction of exergy occurred at a carbonator and a calciner. Liu et al 11 simulated CLG combined with a torrefaction reactor and identified optimal torrefaction and gasification temperatures. Torrefaction was found to enhance the cold gas efficiency and reduce bed material circulation rate.…”