Environmental Engineering Reference
In-Depth Information
Table 2 Dual fluidized bed gasi
cation facilities
Gasi
cation facility
HV MJ/m
3
Size
Bed
material
H
2
(vol%)
CO
(vol%)
CH
4
(vol%)
McNeil plant, Vermont;
DFB
50 MW
22
44.4
15.6
17.3 (HHV)
Gussing, Austria; demo
DFB plant
8 MW Limestone 50.6
16.5
12.9
ECN (DEN) pilot-scale
DFB
800 kW Austrian
olivine
21.2
37.2
12.1
FSU, Florida; single bed 100 kW Silica
28.7
43.5
14.6
16.5 (HHV)
University of Vienna;
lab-scale DFB
100 kW Calcite
65.1
9.3
8.8
13.1
-
16.5 (LHV)
University of Zaragoza,
DFB
45 kW Catalyst
30.1
15.8 (LHV)
ECN (DEN) lab-scale
DFB
30 kW Austrian
olivine
27.3
27.5
9.5
University of Zaragoza,
single bed
20 kW Silica
50
22
6
12.75 (LHV)
Yokohoma, Japan; DFB 25 kW Silica
23.2
37.8
16.9
15.8 (HHV)
Dalin, China; dual
moving beds
5 kW
Olivine
40
30
9
Onogawa, Japan;
circulating DBFB
0.22 kW Alumina
35
27.5
7.5
endothermic, most of the systems cited above require additional heating to maintain
required reactor bed temperature. Since steam generation requires a signi
cant
fraction of the energy and the affordability of the process is questionable. Hence,
only the 8-MW Gussing, Austria plant is currently in operation for power
production (Koppatz et al.
2011
). As a result, a careful investigation of process
thermodynamics along with energy balance needs to be carried out for the design of
an optimal DFB gasi
er. With this in mind, a program of research was undertaken
at FSU to produce affordable hydrogen-enriched synthesis gas using multiple
biomass feedstock.
Figure
2
shows a sustainable DFB gasi
cation facility schematic for a complete
hydrogen-enriched syngas/H
2
production plant. The process begins with renewable
biomass feedstock. The advantage of this facility is that it can process any and all
parts of a biomass, even cellulosic wastes. This increases the total energy ef
ciency
of the syngas production process. The biomass is chipped and dried with the com-
bustion exhaust before being inserted into the gasi
cation reactor. Inside the reactor,
superheated steam is injected at up to 800
°
Cto
fl
fluidize and react with the bed
material. Char formed in the gasi
cation reaction is transferred to the combustor
where it is burned by the addition of air. The heat generated by this combustion is
then put back into the gasi
er to continue the reactions. The superheated steam and
product gas mixture leaves the gasi
cation reactor where it is cooled in a heat
exchanger exiting at a temperature of 350
400
°
C. The gas then goes through the
-
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