1. EFFECT OF STEAM TO BIOMASS RATIO ON GASIFICATION OF BIOMASS
JH Moon, YK Sung, BR Bang, UD Lee*
KITECH, South Korea
The 33rd International Symposium on Combustion, Beijing, China, August 1-6, 2010.
Introduction
Results
In this study, effect of steam on biomass gasification was investigated in a tube furnace. Korean pine woodchip was used as a feedstock, and syngas compositions and yield were monitored as a function of time by varying temperature and steam to biomass ratio.
<700℃ Gas composition>
<800℃ Gas composition>
<900℃ Gas composition>
Syngas is mainly composed of H2,CO,CO2,CH4
The gas yield of steam gasification cases are much lager than pyrolysis
H2 yield is significantly affected by the steam and gasification temperature
<Gas rate at different temperature>
The gasification process can be separated in devolatization and char gasification
Steam has little effect on devolatization process but it can give a significant effect on char gasification
<Carbon conversion>
Carbon conversion is significantly affected by the steam and gasification temperature
Materials and methods
Materials: Korean pine woodchip (Average size: 5mm)
Methods
Biomass pyrolysis and gasification principal
Proximate analysis
Ultimate analysis(Dry basis)
LHV
Moist. VM
Ash FC C H N O S
Wt%
mg/kg
kcal/kg
6.4
75.9
0.3
17.4
50.8
5.4
0.0
43.6
61.8
4,518
Batch type
Sic electric heater
Continuous gas analyzer(ND-IR)
Dry gas meter
Cold traps followed by a ceramic filter
Sample amount: 20g
Steam/Biomass ratio(S/B)
: Pyrolysis, 1/1, 2/1, 3/1
Purging gas: N2 1L/min
Temperature(℃): 700,800,900
Conclusion
High concentration H2 is generated at high temperature and increase of S/B ratio when the biomass steam gasify. H2 concentration is significantly increased above 800℃.
The gasification process can be separated in devolatization and char gasification. Reaction time of devolatization stage at high temperature is shorter than lower temperature. Amount of syngas from char gasification is increased when adding steam.
Reaction time of biomass pyrolysis is about 2 min but on the other hand it is about 18 min at steam gasification and H2 concentration is significantly incresed.