Investigation of Operational parameters and Optimization of Flue Gas Carbon Dioxide Absorption Process by Diethanolamine via Response Surface Methodology

In this study, to evaluate the performance of aqueous diethanolamine (DEA) CO2 absorption process from flue gas, the volumetric overall gas phase mass transfer coefficient (KGaV) and the volumetric mass flux (NAaV) was investigated under different operating conditions, including: inlet solvent temperature 35-55 °C, the CO2 concentration in flue gas 5-15 vol.%, flue gas flow rate 50-100 lit/min, solvent flow rate 0.75- 1.25 lit/min, DEA concentration 15-25 wt.% and reboiler heat load:1.4-2.2 kW. To evaluate the results and optimize the conditions, the Box-Behnken Response Surface methodology was used. The results showed that by increasing solvent flow rate, gas flow rate, reboiler heat load and DEA concentration in the solvent, the NAaV and KGaV values were increased. However, increasing the CO2 concentration in the flue gas increased NAaV, and decreased KGaV. The temperature changes and carbon dioxide concentration through the absorption column showed that carbon dioxide absorption was more in the higher ratio of solvent flow to gas flow rate. However, increasing the length of the column increases the CO2 absorption. Finally, optimization of the operating conditions has been done. The maximization of NAaV and KGaV simultaneously was considered as objective function. At optimal operating conditions, the NAaV and KGaV values reached 15.01 (kmol/h.m3) and 3.07 (kmol / h.m3.kPa), respectively.