(58d) Analysis of Different Solvent Performance in UKy-CAER’s 0.7 MWe CO2 Capture Pilot Plant
AIChE Annual Meeting
Monday, October 29, 2018 - 8:54am to 9:12am
In the UKy-CAER CO2 technology, novel concepts are employed in a heat integrated process to maximize heat utilization to lower the parasitic energy of the capture process. These include, first, a two-stage stripping process for solvent regeneration for enhanced solvent capacity and a reduction in the associated energy for regeneration. Here, after the conventional primary steam-driven solvent regeneration, the lean solvent is sent to a secondary air-stripping column where air is used counter-currently to further lower the lean loading of the solvent providing a higher free-amine solvent to the top of the absorber. The higher CO2 volume air from the top of the secondary stripper is recycled to the plant boiler as secondary combustion air, which in turn would increase the amount of CO2 entering the absorber. The lower liquid phase CO2 concentration from the leaner solvent and higher gas phase CO2 concentration will increase the driving force for CO2 diffusion through the liquid/gas reaction film with resultant higher mass transfer. Second, a heat integrated liquid desiccant-based cooling tower loop recovers waste energy from the CCS, improves power plant efficiency and reduces parasitic load. The benefits for economic savings are derived with the use of advanced solvents with the process.
In this work, the performance of two advanced solvents were evaluated to demonstrate the energy savings of the process. For the more energy efficient advanced solvent, a reduction of about 36% in regeneration energy was obtained relative to DOE reference case 10. The energy ranged from 900 â 1500 Btu/Ib CO2 from the parametric studies. The impacts of process parameters such as solvent circulation, lean loading, stripping temperatures, intercooling effects among others were examined. The heat integrated process is impacted by many process variables acting in tandem. Statistical analysis was used to determine the relative impacts of process variables and showed that intercooling effects in the absorber were more significant for the faster kinetics solvent from the observed temperature profile providing insights to the different behavior of the solvents and how the process could be operated to maximize the energy savings.