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

Abstract

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 commercialscale 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 %.

Process Analysis of Selective Exhaust Gas Recirculation for CO2 Capture in Natural Gas Combined Cycle Power Plants Using Amines

“…It is important to highlight that the estimated L/G ratios are similar to those found in other works for systems with similar flue gas CO2 concentration (e.g. [9,17]), thereby validating the procedure described above. Moreover, the CO2 separation efficiency of the membrane used in the S-EGR case is fixed at 95%, whilst the pressure drop of both the air and flue gas across the selective membrane is assumed to be of 0.1 bar (approx.…”

“…This value is in accordance with previous studies on similar amine systems capturing CO2 from a diluted (3.9%vol. CO2 in this case) flue gas stream (see for example [8,17]). …”

“…as the solvent. The solvent lean loading was fixed at 0.2 mol CO2/mol MEA, as it was shown to be optimal in previous studies [17]. The temperature of the flue gas entering the absorber was fixed at 40°C, and the stripper reboiler was taken to operate at 1.75 bar.…”

“…The design procedure followed for the absorber and stripper columns was similar to that shown in previous works [9,17]. The column diameter was calculated according to two criteria [9,17]: (i) a maximum flooding factor of 80%; (ii) a maximum pressure drop across the columns of ~204 Pa/m, which is a recommended value for moderately foaming amine systems [18].…”

Effect of the CO2 enhancement on the performance of a micro gas turbine with a pilot-scale CO2 capture plant

“…The lean loading is fixed at 0.2 mol CO 2 /mol MEA for all the cases. The solvent flow rate was estimated based on the 90 % CO 2 capture rate, and also it has been verified by the literature (Agbonghae et al, 2014). Further, the solvent flow rate varies from 404 kg/hr at no injection of the CO 2 to 600 kg/hr at CO 2 injection of 125 kg/hr.…”