Influence of solvent properties on capture cost

“The screening discloses the interaction between chemistry, thermo-physical properties, and techno-economic performance and is highlighted by a sequential step-by-step optimization of the solvent’s properties starting with MEA and reaching the limiting solvent (see Fig. 4). The biggest cost contributors are steam and the absorber, with the operating expenditure dominating the overall capture cost. The first optimization step involves the transport properties (i.e., viscosity, heat capacity, thermal conductivity, surface tension, and density), the second step includes kinetics, the third one is heat of absorption, and the last step, the VLE. The limiting solvent shows that improved heat and mass transfer rates lead to lower solvent flowrate and smaller equipment. The specific reboiler duty decreases to 1.55 MJ/kgCO2, which is roughly a third of MEA’s reboiler duty and 34% lower than CESAR1. We predict a lower limit of $26/tCO2 for capture cost (34% of MEA’s capture cost) for the limiting solvent utilized in an archetypal process capturing 90% of the CO2 in a typical gas-power flue gas. We observe the upper bound of the second law efficiency of an archetypal post-combustion capture unit to be limited to 32% (gas-power) and 55% (coal-power).”


Fig. 4. Deriving the limiting solvent starting from MEA by optimizing the solvent properties and its impact on capture cost (colour bar, left scale) and specific reboiler duty (red, right scale) at flue gas CO2 concentration of 4 mol% and 90% capture rate.”


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