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.