Over 60% of carbon dioxide (CO2) sent to the atmosphere comes
from fired heaters and utility or industrial power systems based
on fossil-fuel combustion.1 The industrial capture of CO2 from
emissions is possible with low pressure solvent absorption, a
simple process operation that becomes particularly important for
combustion furnaces, burners and incinerators. Traditionally,
the absorption of acidic gases has been done under pressure with
amine solutions, but typical combustion flue gases have large
flowrates. Inert N2 is the bulk constituent and CO2 is generally
diluted to 10% vol15% vol. Fig. 1 shows the example of a tenfold
polytropic compression at the 80% optimistic efficiency for
100,000 Nm3/h, a relatively small industrial gas flowrate. The
compression requires 12 MWh or 3.2 kW per kmole of gas and
determines a net loss, in spite of the power that can be
recovered through a turbine expander, located on the lighter
CO2-free gas returning from the absorber, and the heat
recuperated from various intercoo