Model Development, Validation, and Optimization of an MEA-Based Post-Combustion CO₂ Capture Process under Part-Load and Variable Capture Operations

Existing power plants are frequently load-following due to increasing penetration of the renewables into the grid. For power plants integrated with CO2 capture, optimal operation of the capture unit at part-load and variable capture conditions can be exploited to reduce the operating costs. This paper presents insights into the performance of a reference monoethanolamine (MEA)-based post-combustion CO2 capture unit under steady-state part-load and variable capture operations. A rigorous plant-wide model for the capture unit is developed in the Institute for Design of Advanced Energy Systems computational platform. The contactor model is validated with the data from a wetted wall column (WWC) and two pilot plants. The plant-wide model is used for steady-state optimization under part-load operations and variable capture rates using flue gas similar to pulverized coal and natural gas-combined cycle power plants. Analysis on the performance of the reference rich/lean amine heat exchanger shows that the hot-end temperature approach can considerably vary under part-load operations for a given heat exchanger area. The study shows that if the plant is not optimally operated under part-load and variable capture operations, there can be a high penalty depending on the deviation of the liquid/gas flowrate with respect to its optimal value. This study shows that the optimal operation of an existing capture unit is crucial for minimizing the energy penalty under part-load and variable capture operations.

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