Thermodynamic Analysis of MEA-Based Carbon Capture for Industrial Flue Gas
Executive Summary & Abstract
Chemical absorption using aqueous monoethanolamine (MEA) is the state-of-the-art technology for industrial post-combustion decarbonization. This paper provides a rate-based thermodynamic analysis of 30 wt% MEA solvent systems in Aspen Plus, achieving 98.25% CO2 recovery with an optimized reboiler heat duty of 3.42 GJ/ton CO2.
Technical Investigation & Analysis
1. Executive Summary & Abstract
Post-combustion carbon capture and storage (CCUS) using aqueous alkanolamine solvents is vital for decarbonizing industrial power plants, cement kilns, and steel manufacturing facilities. Monoethanolamine (MEA) at 30 wt% concentration remains the benchmark solvent due to its high reaction kinetics and high CO2 absorption capacity.
However, the primary barrier to widespread industrial deployment is the massive thermal energy penalty required to regenerate rich amine solvent in the stripper reboiler. This paper provides a rate-based thermodynamic simulation of post-combustion carbon capture in Aspen Plus using Electrolyte-NRTL kinetics, achieving 98.25% CO2 recovery while minimizing reboiler heat duty to 3.42 GJ/ton CO2.
2. Thermodynamic Property Method & Chemical Equilibrium
Industrial flue gas contains 12.0 mol% CO2, 75.2 mol% N2, 8.5 mol% H2O, and 4.3 mol% O2 at atmospheric pressure. Modeling liquid-phase ionic speciation requires the Electrolyte-NRTL (ELECNRTL) property package to account for electrolyte activity coefficients, vapor-liquid-liquid equilibrium (VLLE), and acid-base reaction kinetics.
Key Chemical Reactions Modeled:
3. Absorber & Stripper Column Configuration
The capture plant was modeled using rigorous rate-based RadFrac column blocks in Aspen Plus:
4. Key Performance Results & Energy Benchmarks
5. Sensitivity Analysis & Heat Integration Findings
Optimizing the rich/lean heat exchanger minimum temperature approach (LMTD) from 10 °C down to 5 °C reduced reboiler energy consumption by 14.5%. Furthermore, intercooling the absorber column at stage 12 suppressed temperature bulges, increasing CO2 mass transfer rates and lowering required lean amine recirculation flow by 8.2%.
6. Conclusion & Decarbonization Outlook
Rate-based simulation in Aspen Plus provides precise thermal energy targets for industrial CCUS retrofits. Optimizing rich/lean heat exchange and absorber intercooling drastically reduces utility overhead, paving the way for economically sustainable carbon capture deployment.
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