(78d) An Energetic Comparison Between Heat Integrated Pressure-Temperature-Swing Adsorption Using Alkaline-Earth Oxide Sorbents and Amines for the Capture of CO2 From Coal Fired Plants



In this work, we present a comparison on an energy basis between a heat integrated process using Alkaline-Earth Oxide sorbents and traditional amines for the capture of CO2 from the flue gas of coal-fired plants. State of the art amines require 1550 Btu/lb of CO2 captured. This drastically reduces the output and efficiency of the plant since this energy is drawn from low-pressure steam used to heat the reboiler of the amine process instead of producing useful work.  An alternative design relies on using Alkaline-Earth Oxide sorbents in a multi-bed arrangements and cycle of desorption/adsorption steps to adsorb the CO2 from the flue gas and desorb it in a water stream at lower pressure (higher temperature) before sending the mixture for separation, liquefaction and sequestration. The heat integration part involves using a heat-pump cycle around the adsorber/desorber unit to channel the heat released by the lower temperature exothermic adsorption reaction in the adsorber to the higher temperature endothermic desorption reaction occurring in the desorber. Current studies based on modeling the adsorber/desorber beds as equilibrium reactors show a 10% increase in output at the same level of CO2 capture when compared with amines.