Biomass gasification using chemical looping (BGCL) is an innovative biomass gasification technology,
which utilizes lattice oxygen from oxygen carrier instead of molecular oxygen from air. This work
attempted to investigate the BGCL performance with nickel-based oxygen carrier in a 25 kWth reactor.
The new prototype is composed of a high velocity fluidized bed as an air reactor, a cyclone, a bubbling
fluidized bed as a fuel reactor, and a loop-seal. At first, the major reactions in the process were presented
and chemical reaction thermodynamics in the fuel reactor was analyzed. The NiO/Al2O3 oxygen carrier
was then applied in the reactor. Different variables, such as gasification temperature, steam-to-biomass
(S/B) ratio and NiO content, were analyzed. The carbon conversion efficiency increased smoothly within
the temperature range of 650e850 C, while the syngas yield reached the maximum of 0.33 Nm3kg1 at
750 C. Additionally, based on the tradeoff between carbon conversion efficiency and syngas yield, it was
concluded that 30 wt.% was the optimal NiO content. Besides, in order to get high quality syngas with
low CO2 emission, CaO-decorated NiO/Al2O3 oxygen carrier was investigated. Experimental results
showed that the addition of CaO enhanced the biomass gasification process and increased the syngas
yield.
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