Gas Treatment and Energy Recovery
The flue gas treatment and energy recovery section of the flowsheet
performs on water removal and compression of the flue gas and expansion
of the N2-enriched product of the separator. Ideally,
these expansion and compression systems will share a joint driveshaft to
reduce mechanical efficiency losses. The compression of the flue gas
feed to the target condition is carried out via two-stage compression,
with pressure ratios between 3 and 5. Multiple intercoolers are used to
make the compression more efficient while also providing boiler
feed-water (BFW) preheating for the plant. Further discussion of BFW
integration can be found in the Supporting Information S1.2. Using just
the first stage of compression, the heat for the first three boiler
feed-water preheaters is provided as modeled in comparison to DOE Base
Case 11a.34 Cooling water can then be used to cool the
feed gas. The compressed gas can be further cooled between compression
stages using excess low quality (> 0 °C) cooling available
from the product and byproduct gas. Following the second compression
stage, the gas is cooled to 2 °C to further dehydrate the gas prior to
the complete drying necessary to enter the sub-ambient heat exchange
system.