(628g) ASPEN Plus Simulation of Combined Biomass Gasification and Fisher-Tropsch Synthesis of Liquid Fuels

APSEN Plus Simulation of Combined
Biomass Gasification and Fisher-Tropsch synthesis of liquid fuels

Mohammad Rafati, Lijun Wang,
Abolghasem Shahbazi

Abstract

Combined biomass gasification and
subsequent Fischer-Tropsch (FT) synthesis is a promising pathway to replace the
fossil-based fuels. In a FT process, a mixture of H₂ and CO (syngas)
is converted to dominantly olefins and paraffins with various carbon
chain-length in the presence of typically a Fe- or Co-based catalyst. CO₂
is a major constituent of syngas derived from biomass gasification which it
typically removed from syngas with expensive and energy intensive separation
unit operations prior sending the syngas to the FT reactor. CO₂
could be reactive in presence of Fe-based catalysts as Fe exhibits water-gas
shift activity, in contrast to Co-based catalysts.  We have developed and examined several
process flow diagrams of combined gasification and FT synthesis for the
production of liquid fuels from biomass using the ASPEN PLUS process modeling
package. Intrinsic kinetic rate equations and detailed product distribution models
of Fe- and Co-based catalysts are implemented into a FT reactor block using
FORTRAN subroutines to accurately compare the effect of FT catalysts on process
product distribution. The effects of various process parameters including
catalyst type and recycling ratio on carbon conversion efficiency, energy
conversion efficiency, and CO₂ emissions are examined.