Comparative Study of Membrane and Absorption Processes Performance and their Economic Evaluation for CO2 Capturing from Flue Gas

As the main aim of this study, simulation and economic assessment of membrane technologies in comparison absorption process for CO2capturing from specified flue gas was conducted. For this purpose, the PRO/II v.10 software and Aspen Process Economic Analyzer v.10 were used. In this simulation, the flue gas flow rate is 8162 kmole/h and the concentration of CO2 in flue gas is 8-22% mole. The objective function in the simulation of CO2 capturing is to remove 85% of CO2 from the flue gas stream. The amount of required solvent and membrane surface, as well as various costs such as equipment costs, installed costs, total capital cost, total utility cost and total operating cost for different concentrations of CO2 in flue gas (8-22% mol.) was assessed for both membrane-based and absorption-based units. For CO2 selectivity and permeability values of 28 and 1097 barrer, respectively, the total capital cost in the membrane-based process is very higher than the absorption process. So, the total capital cost of the membrane unit was about 2.3 times higher than the total capital cost of the absorption process. In a low concentration of CO2, the total utility cost and total operating cost of the membrane-based process were about 2.2 times higher than the absorption process. However, by increasing the CO2 concentration the difference between these costs in two processes decreased. By analyzing the selectivity effects on the total capital costs, it is obtained that with a selectivity value of 280 and the same permeability the costs of the membrane-based process became comparable to the costs of the absorption process.