The bio-oil stabilization system incorporates four process steps,
an extractor operated at 23 C and 3.5 MPa followed by three high
pressure separators operated at 3 MPa, 2 MPa, and 0.2 MPa. Extraction
is carried out in a counter-current liquid–liquid extraction column
with preheated and pressurized bio-oil entering at the top
and near critical propane solvent entering through the bottom at
a conservative solvent to feed ratio of five to one. The mixture then
flows to the first separator where the pressure is reduced and a
portion of the propane is removed. This is repeated through the
second and third separator. The pressure is stepped down through
the collectors to minimize energy requirements for solvent recycle.
Propane that is removed from the first extractor does not require as
much energy for recompression before it is recycled back into the
extractor, compared to propane that is recovered in the last separator.
The solvent is condensed to a liquid state by cooling, and any
non-condensable components are purged from the system. The
recycle stream is pressurized, reheated, and pumped back to the
extractor. Make up solvent