(125a) Amine Absorption with Vacuum Stripping for Post-Combustion Carbon Capture

As a part of this work, we have performed a comparison of 4 amine-based absorbents for CO₂ capture from a pulverized coal-fired power plant capture under a wide range of stripper operating conditions. We explore a range of stripper operating pressures between 30 kPa and 300 kPa. For performing the simulations, we use the process simulation software ProMax^® with TSWEET^®. The criteria for comparison of absorbents are the energy requirement and and stripper dimensions for 90% CO₂ capture (separation + compression) from a 400 MW pulverized coal fired power plant. Separated CO₂ is compressed to a pipeline pressure of 8MPa. The amine absorbents considered for comparison are monoethanolamine (MEA), diethanolamine (DEA), diglycolamine (DGA) and 2-amino-2-methyl-1-propanol (AMP). The parameters explored as a part of this study includes – amine absorbent concentration and stripper pressure. On the basis of our findings, we report that diglycolamine (DGA) and diethanolamine (DEA) are superior absorbents than monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP) for CO₂ capture. Operating at a high pressure (e.g. 300 kPa) and under low vacuum (e.g. 75 kPa) is more advantageous than the conventional stripper operation (e.g. 150 kPa). A higher stripper pressure reduces the overall energy requirement for CO₂ capture by decreasing the stripping steam requirement as well as reducing the compression costs. A vacuum stripping unit operates at a lower temperature and can consequently use very low pressure steam, downstream of the Low Pressure (LP) turbine. The more advantageous of the two configurations will depend on various factors like corrosion costs – which increase with pressure and equipment sizing – which decreases with pressure.