Optimal Process Design of Commercial-Scale Amine-Based CO₂ Capture Plants

Reactive absorption with an aqueous solution of amines in an absorber/stripper loop is the most mature technology for postcombustion CO 2 capture (PCC). However, most of the commercial-scale CO 2 capture plant designs that have been reported in the open literature are based on values of CO 2 loadings and/or solvent circulation rates without an openly available techno-economic consideration. As a consequence, most of the reported designs may be suboptimal, and some of them appear to be unrealistic from practical and operational viewpoints. In this paper, four monoethanolamine (MEA) based CO 2 capture plants have been optimally designed for both gas-fired and coal-fired power plants based on process and economic analyses. We have found that the optimum lean CO 2 loading for MEA-based CO 2 capture plants that can service commercial-scale power plants, whether natural-gas-fired or coal-fired, is about 0.2 mol/mol for absorber and stripper columns packed with Sulzer Mellapak 250Y structured packing. Also, the optimum liquid/gas ratio for a natural gas combined cycle (NGCC) power plant with a flue gas composition of approximately 4 mol % CO 2 is about 0.96, while the optimum liquid/gas ratio for a pulverized-coal-fired (PC) power plant can range from 2.68 to 2.93 for a flue gas having a CO 2 composition that ranges from 12.38 to 13.50 mol %.