Efficiency Improvement of CO2 Capture

Abstract

Carbon dioxide capturing processes from industrial gases are widely applied to enrich valuable gas and to reduce green-house gas emission. The highest amount of anthropogenic CO2 is emitted in flue gas form. Flue gas composition varies in a wide scale therefore designing such plants that are able to operate on a good removal efficiency scale is vital. A typical method for such gas separation is an absorber-desorber system where the absorbent is 30 w% aqueous monoethanolamine solution.
The aim of this work is to setup computer based process model that is capable of simulating CO2 capture from flue gases and to study its performance at different operating conditions. We investigate possible process improvements by enhancing the CO2 removal efficiency with the variation of different key parameters and different plant setups. We also take into account the regeneration energy demand by optimizing the system to the lowest specific energy demand. Results show that the least attractive option is the overload of the existing absorber-desorber system. By introducing a second absorber-desorber step, high removal efficiency can be reached while maintaining low desorber temperature. The best performance can be achieved with increasing the absorber height and elevated desorber pressure that can reduce the specific regeneration energy especially at high removal efficiency region. This result is in agreement with the argued classical absorber design and operation philosophy that the absorber should be operated at extremely low loads, which is in association with overdesigned absorber column packing heights. This offers the possibility for flexible operation.