Approaching a reversible stripping process for CO2 capture

Amine scrubbing is the most mature CO2 capture technology for coal-fired power plants. However, the energy consumption for regeneration incurs a 20-25% penalty on electricity output. This loss can be reduced by alternative stripper design. This work uses exergy analysis to quantify the inefficiencies and demonstrate the effectiveness of a new configuration, the advanced flash stripper, without having to consider numerous alternatives. The lost work from the overhead condenser and the cross exchanger makes the simple stripper inefficient. The advanced flash stripper successfully eliminates the lost work of the condenser and improves the reversibility of the cross exchanger. It reduces the reboiler duty by 16% and the overall work requirement by 11% compared to the simple stripper. The new design when used with piperazine showed a remarkable 74% thermodynamic efficiency. Further improvement of energy efficiency is expected to be marginal. This work not only provides a better design that reduces the energy consumption, but also indicates that the state-of-the-art is approaching the theoretical work limit.