Environmental Engineering Reference
In-Depth Information
Table 7. Main simulation results and details of calculated syngas characteristics
Cycle main results
Syngas characteristics at gasific a tion reactor exit
Gasification air mass flow rate [kg/h]
23.112
Temperature [°C]
875
Evaporated water in the scrubbing
process [kg/h]
1.080
Mass flow rate [kg/h]
31.197
Syngas mass flow rate after scrubbing
process [kg/h]
32.277
LHV [kJ/kg]
2.210
Combustion air mass flow rate [kg/h]
34.700
Compounds
Mass fraction
Exhausts mass flow rate [kg/h]
66.977
N 2
0,59
Steam produced in the first syngas
cooler [kg/h]
9.870
CO
0,096
Steam produced in the boiler [kg/h]
18.072
CO 2
0,176
Exhausts boiler exiting temperature
[°C]
200
H 2 O
0,124
Turbine power output [kW]
5.345
H 2
0,01
Pump consumptions [kW]
72
Other trace compounds
0,004
Table 8. Gasification and energy recovery cycle synthetic results
Combustible fraction
Waste mass flow rate [kg/h]
9.537
LHV [kJ/kg]
12.201
Entering thermal power [kW]
32.322
Net Power output [kW]
5.273
Net efficiency [%]
16,31
CO 2 mass flow rate output [kg/h]
10.280
Pyrolysis with Energy Recovery
The simulation of the pyrolysis process with energy recovery was carried out using the
commercial software Aspen Plus ® (Aspen Technology Inc.), considering as input only the
combustible fraction, in reference to the elemental composition and mass flow rate reported in
table 3.
The simplified schematic of the proposed pyrolysis process with energy recovery is
shown in figure 4.
The waste enters the pyrolysis reactor were the temperature is kept at the assumed value.
A syngas is produced and the solid products/residues are discharged from the bottom. In this
study the attention was focussed on syngas production, rather than on liquid and solid
outputs, since the assumed operating temperature is relatively high. Part of the syngas is burnt
to supply the heat required by the pyrolysis reactor. The remaining syngas is burnt with air
combustion in a reciprocating engine to produce electric energy. This layout solution was
proposed on the basis of the very good LHV obtained for the pyrolysis syngas, which can be
accepted by the reciprocating engine. The possibility of using relatively high efficiency
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