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Indicators for sustainability assessment 93

10 Pretreatment of bagasse

The pretreatment step comprehends drying, roasting, and crushing, and pre-
pares biomass for the fluidized bed gasification process, providing adequate
granulometry and humidity, and improving energy density.

11 Production and cleaning of syngas

Production and cleaning of syngas encompasses the gasification steps in flu-
idized bed and cleaning of the obtained gas. Gasification is a complex pro-
cess, sensitive to several factors such as gasification temperature, equivalence
ratio, biomass granulometry, and demands oxygen with elevated purity.
Therefore the production step of syngas includes a unit for air separation,
which produces the oxidizing agent for gasification. The quality of syngas
limits its utilization in other processes, and therefore cleaning has the objec-
tive of removing unwanted compounds, enabling its utilization in BIG-
GTCC cycles and in FT synthesis.
Fig. 4.13 presents the mass balance of the syngas production step. It con-
siders the energy flows associated with the processing of 1 tonne of sugarcane
for the Base Case (BSE), where 50% of syngas goes to the FT synthesis and
50% to the BIG-GTCC.

Dryer Electricity Electricity Electricity
agent in 26 kWh 4.9 kWh 41.16 kWh
Pretreatment
Bagasse Bagaço Bagasse
50% moisture Dry 15% moisture Torrefaction torrefeid Grind
1000 kg 588 kg 411.6 kg

Torgas Torrefied bagasse
176.4 kg
Dryer agente out Water granulometry 0.1 mm
412 kg 411.6 kg
Syngas
production
Electricity
12.8 kWh
Electricity ASU O 2 Gasification
86.4 kWh 288.1 kg
Ash
14.4 kg
Syngas
Electricity 685.3 kg
2.54 kWh
Rectisol
Acid gases
Steam (4.8 bar, 180°C) (CO 2 e H 2 S)
33.6 kg 211.4 kg
Clean syngas
473.9 kg
Fig. 4.13 Mass and energy balances for the production and cleaning of syngas.