Simulated concentration profiling of liquid-phase products in the quaternary solvent system of (carbon dioxide + monoeth-anolamine / diethanolamine + triethanolamine + water)

Abstract

An understanding of the potential environmental impacts of amine solvents used in Carbon Capture and Storage (CCS) is important as more of these technologies are moving to the pilot stage of development and will be more regularly operated. It is clear that solvents with otherwise promising performance may have challenges and considerable inherent problem due to by-product formation, of which often neglected. In this regard, it is also necessary to study the concentration profiles of the by-products formed in aid of treating liquid waste streams. The study also includes the chemistry and reaction mechanisms of amine transformation products. The studied quaternary systems in varying blends were generally written as CO2- amine-TEA-H2O, where amine could be MEA or DEA. TEA corresponds to triethanolamine, MEA to monoethanolamine, and DEA to diethanolamine. The simulation was done using Aspen Plus® v8.6 at different mass flow rates (kg/h): 500, 750, and 1,000; temperatures (oC): 25, 30, 35, 40, 45, and 50; and pressures (atm): 1, 2, and 3. The results shows direct proportionality between the efficiency and solvent’s flow rate, pressure, higher secondary amines ratio along with temperature in majority. At constant temperature, pressure, and mass flow rate, the highest removal efficiency was that of MEA-TEA (10-20 %wt) and the lowest was DEA-TEA (10-20 %wt). In addition, the results yield reasonable predictions on liquid-phase product concentration profiles. The components behave according to their expected trends and the results are very promising.