Evaluation and characterization of reboiler heat-duty for carbon dioxide absorption process using single- and blended-alkanolamines.

摘要

Gas absorption process using aqueous solutions of alkanolamines is a promising technology for capturing carbon dioxide (CO2) from high-volume and low-pressure industrial flue gas streams for the purpose of greenhouse gas mitigation. At present, the cost of this process is prohibitively high due to the intensity of energy used during solvent regeneration. This creates a great incentive to improve the existing process by developing a new design and operation strategy for the reduction of energy requirement for solvent regeneration. To achieve such improvement, adequate and reliable data of reboiler heat-duty must be available and also the behavior of reboiler heat-duty must be understood.; This work focuses on extending the knowledge of the reboiler heat-duty of the CO2 absorption process using aqueous solutions of both single- and blended-alkanolamines. The reboiler heat-duty was measured directly from a bench-scale gas stripping and solvent regeneration system. The obtained data were correlated as a function of process parameters, including CO 2 loading of lean- and rich-solutions, alkanolamine type and concentration, and composition of blended-alkanolamine. The results show that the reboiler heat-duty increases with decreasing lean- and rich-CO2 loading but is not sensitive to the alkanolamine concentration. Monoethanolamine (MEA) requires the highest reboiler heat-duty followed by diethanolamine (DEA) and methyldiethanolamine (MDEA). Adding MDEA or 2-amino-2-methyl-1-propanol (AMP) to MEA or DEA reduces the reboiler heat-duty to different values depending upon its mixing ratio. Synergy exists between mixing ratio and reboiler heat-duty. MEA-MDEA and DEA-MDEA are mostly regenerated by CO2 flashing, but MEA-AMP is not.