(500g) Chemical Looping Gasification and Hydrogen (CLGH) Process from Solid Biomass in a Dual Fluidized-Bed System

Chemical looping
gasification and hydrogen (CLGH) process from solid biomass in a dual fluidized-bed
system

Jimin
Zeng, Rui Xiao^*,
Yihong Wang, Shanshan Shao and
Dewang Zeng

Key Laboratory of Energy Thermal
Conversion and Control, Ministry of Education, School of Energy and
Environment, Southeast University, Nanjing, 210096, P.R. China

E-mail: ruixiao@seu.edu.cn

ABSTRACT

Chemical looping gasification (CLG) process is one of CO₂
capture technologies for producing syngas with high system conversion
efficiency and inherent separation of CO₂. Chemical looping hydrogen
(CLH) process with renewable energy sources is the other promising technology
for producing H₂ and decreasing emission of greenhouse gas. Chemical
looping gasification and hydrogen (CLGH) process from solid biomass is a
promotion of the existing steam-iron process by combining CLG process and CLH
process in one step (Fig. 1).

This process in a dual fluidized-bed system can not only avoid highly
concentrated CO₂ gas but also generate hydrogen with no direct
efficiency loss. Meanwhile, the system offers two separate fluidized-bed
reactors for biomass gasification and H₂ production. Iron-based
oxygen carrier is used as bed material in the two fluidized beds to provide
with lattice oxygen for gasification in the gasifier and to create a reduced
environment for H₂ production in the reducer. In this study, the
experiment for CLGH process with pine sawdust was conducted in a dual
fluidized-bed system, aiming to a suitable H₂/CO-ratio syngas and
the best H₂ yield for the whole system. The effects of gasifier
temperature, reducer temperature, steam preheating temperature and
steam-to-biomass ratio (S/B) on the process were investigated. The optimum
operating conditions concluded in the experiment were: gasifier temperature at
760 °C, reducer temperature at 780 °C, steam preheating temperature at 500 °C and S/B at 1.0 kg/kg. At this condition, the H₂/CO-ratio syngas of 1.22 mol/mol and H₂ yield in the reducer of 0.735 Nm³/kg were obtained. And the results enhance understanding of CLGH process and facilitate
commercial utilization of solid biomass.

Key words: Chemical looping gasification and hydrogen; A
dual fluidized-bed system; Biomass