467987 Dynamic Simulation of CO2 Absorption Using Mixtures of Solvents
Jorge Gabitto and Costas Tsouris
The removal of CO2 from gaseous streams is a very important industrial technology with applications in (i) reduction of greenhouse gas emissions from flue gases in coal-fired power plants and (ii) removal of radioactive C14 in the nuclear industry, among others. One of the well-known technological alternatives for CO2 capture is absorption/stripping with aqueous solvents, such as alkanolamines and their mixtures. A dynamic model of the absorption process for dilute carbon dioxide mixtures in mixed solvents solutions is proposed. A new reaction scheme that allows the use of different solvents has been added to increase the versatility of the proposed model. Chemical reactions between CO2 and the high pH solution have been included in the model through the use of an enhancement factor for chemical absorption. Interfacial equilibrium constants have been calculated based upon Henry’s constant values for the different gas-phase species calculated using fugacity ratios obtained by the Peng-Robinson equation of state. Mass and energy balances have been derived for all the species in the gas and liquid phases. Numerical techniques have been used to calculate the axial profiles of temperature and concentrations of the resulting species in both phases. The model has been validated using experimental data available in the literature for different columns, packing materials, and operating conditions. Simulations under different operating variables and dynamic inputs have been conducted. Simulation results for different solvents have been compared and analyzed. These results show the potential of the proposed model to optimize the operation and control of these separation processes.