Environmental Engineering Reference
In-Depth Information
Fig. 10 Equilibrium syngas
composition (Koppataz et al.
2011
)
region was required to be in excess of 1,100
C. At this temperature, corrosion of
the reactor exterior surface occurred rapidly. As a result, the reactor surface would
shed oxidized metal dust and
°
flakes that accumulated in the gap between the heaters
and reactor surface. This collection of solids created an electrical bridge between
the heaters and the reactor, short circuiting the heaters. The resulting electrical
discharge destroyed heaters and deformed the reactor surface. To test gasification
at higher temperatures, a reactor material capable of withstanding such high tem-
peratures is necessary, or oxygen must be eliminated from the environment.
Due to the dif
fl
C, most
experimental facilities do not test above this temperature. Equilibrium models, such
as the one by Koppatz et al. (
2011
) shown in Fig.
10
, predict a slow increase in
hydrogen concentration until 1,000
culty of reaching gasi
cation temperatures above 850
°
C. Equilibrium models usually over predict
hydrogen concentration at low temperatures due to slow reaction rates that resist
changes in composition. When reactor temperature is increased to 800
°
C and
above, experimental results tend to more closely match equilibrium predictions.
This explains the linear trend seen in the hydrogen concentration measured in this
study. It is expected that at higher temperatures, the hydrogen concentration will
taper off similar to the prediction of the equilibrium models.
°
3.2 Syngas Heating Value
The syngas heating value is an important parameter when determining the possible
end uses for syngas. When used as a fuel to power an engine or turbine, the heating
value must be within acceptable limits of the particular device. Hydrogen-enriched
syngas can have a high heating value per unit mass, while having a low heating value
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