A bench-scale unit was fabricated and used to investigate use of carbonic anhydrase (CA) promoted K2CO3 solvent as an option for CO2 capture from coal-fired power plants. Bench-scale parametric tests were performed at various CA concentrations, solvent flow rates, and reboiler duties. The CO2 capture efficiency significantly increases, and regeneration energy requirement decreases, with increasing CA concentrations up to 2.5 g/L, with capture performance leveling off at higher enzyme doses (up to 4 g/L). Thus, at higher enzyme doses, the capture efficiency is equilibrium rather than kinetically controlled at the top of absorber, when using solvent regenerated via vacuum stripping at high (>35%) lean carbonate to bicarbonate (CTB) conversion levels, which limits the driving force for CO2 absorption. The CO2 capture efficiency also increases when reboiler duty was increased from 0.85 to 1.1 kW, although this also increases the regeneration energy penalty. In contrast, the effect of solvent flow rate on CO2 capture efficiency is less pronounced. Further improvements to the CO2 capture process using CA promoted K2CO3 solvent with low temperature vacuum stripping could be potentially advanced by lowering vacuum pressure, improving strategies for increasing rich CTB conversion (e.g., advanced packing column and optimized L/G ratio), and decreasing absorption temperature.
|Number of pages
|Industrial and Engineering Chemistry Research
|Published - Dec 7 2016
Bibliographical noteFunding Information:
This material is based upon work supported by the Department of Energy under Award Number DE-FE0007741. The guidance of Andrew P. Jones, Project Manager in DOE/NETL’s Carbon Capture Division, for this work is gratefully acknowledged. The authors also acknowledge the constructive discussions with Charles Freeman, Mark Bearden, and Greg Wyatt from the Pacific Northwest National Laboratory, and David Fitzgerald and Jonathan Slater from Doosan Power Systems.
© 2016 American Chemical Society.
ASJC Scopus subject areas
- Chemistry (all)
- Chemical Engineering (all)
- Industrial and Manufacturing Engineering