Sub-ambient CO2 Capture
via Heat Integrated Multi-stage
Separation
Hybrid separations like the one considered here have a variety of
operating conditions that may be varied to boost the performance of the
separation. Operating a PSA or membrane system at higher pressures,
lower levels of vacuum, or different temperatures can have wide ranging
effects on performance. This discussion focuses on the direct effects of
changing these parameters on the economics and energetics of the process
assuming the separation performance is held constant. The overall
process flowsheet is first described in some detail, after which, the
sensitivity of the CO2 capture process energetics are
discussed in detail as they relate to four important operating
conditions: 1. primary separator high pressure condition, 2. primary
separator vacuum condition, 3. primary separator temperature, and 4.
liquefaction pressure. The first three variables play a major role in
the size and performance of the primary separator. The liquefaction
pressure is the key parameter controlling the system temperature profile
when overall system recovery is held constant.