(235b) Experimental Validation of a Rigorous Model for CO2 Post-Combustion Capture System Using Monoethanolamine (Mea)

Since large scale CO2 capture operations are very expensive to build for research purposes, process simulation and modelling have an important role to play for system optimization and in evaluation of the various process alternatives. A computational model of the regeneration system of a monoethanolamine (MEA) based absorption plant for CO2 removal has been developed. The rigorous steady-state model consists of both an absorber and a desorber with connecting unit operations; cross flow heat exchanger, condenser, reboiler and pumps. The desorber gives numerical solutions that exhibit narrow regions of very fast variation and a collocation algorithm for solving stiff boundary-value problems is used. Much of the work includes developing a stable solution strategy for the stiff system. Progressively lower under-relaxation is used during the sequential iterations around the unit operations. The mass transfer model for the absorber is based on the penetration theory, while the speciation in the liquid phase has been described with the use of a modified Kent-Eisenberg model, tuned to fit experimental data at the desorber temperatures. The model has been validated using data obtained from a fully computerized pilot plant built in our labs. The plant consists of a 4.36 meter absorber and a 4.1 meter desorber, capable of removing about 20 kg CO2 per hour. The experimental data have been gathered in a time frame of 3 months continuous operation. The goal is to use the model to run the entire CO2 capture spreadsheet at an optimum by minimizing the energy demand required for regenerating the amine solution. Important parameters have been identified and varied in order to see the overall performance effects, which determines the majority of the operational cost of the overall gas cleaning process. The reduction of the energy demand required for CO2 post-combustion capture is essential in order to make this strategy a viable option for mitigation of the atmospheric CO2 emissions from coal- and natural gas fired power plants.