Process Simulation and Techno-Economic Analysis of CO₂ Capture from Syngas Using Potassium Carbonate in Aspen Plus
Process Description
A chemical absorption system is simulated in Aspen Plus to model carbon dioxide (CO₂) capture from syngas using an aqueous potassium carbonate (K₂CO₃) solution. The simulation utilizes the Electrolyte Non-Random Two-Liquid (Electrolyte NRTL) thermodynamic model, which accurately represents the behavior of electrolyte systems involving ionic species in aqueous phases. A rate-based approach is applied to simulate mass transfer in the packed columns, providing a more realistic representation of the absorption and desorption processes.
In the absorber column, syngas containing CO₂ enters from the bottom, while lean K₂CO₃ solution is introduced from the top. As the streams flow counter-currently through packed internals, CO₂ is absorbed into the solvent. The purified syngas exits the top of the column, while the CO₂-rich solvent leaves from the bottom. This stream undergoes depressurization through a pressure relief valve and enters a flash drum, where steam and acid gases are released. The partially degassed solution is then fed into a stripper column comprising 12 stages. Heat supplied at the reboiler facilitates CO₂ desorption, regenerating the solvent, which is subsequently cooled and recycled to the absorber with the addition of makeup solution.
The model includes hydraulic calculations to assess pressure drop and column performance based on the specified internals. Aspen Plus Economic Analyzer is used to estimate capital and operating costs, while process emissions are quantified to evaluate environmental performance. This simulation serves as a foundation for further optimization, integration with upstream or downstream processes, and scale-up for industrial carbon capture and storage (CCS) applications.
Process Flow Diagram
Project Insights
Solvent Selection
Potassium carbonate offers a low-cost, non-toxic alternative to traditional amine-based solvents.
The electrolyte NRTL model enables accurate representation of ionic equilibrium behavior.
Rate-based Modeling
Rate-based approach captures real mass transfer resistance across packed column stages.
Provides more precise predictions of absorption performance under varying conditions.
Economic Evaluation
Capital and operating costs were estimated using Aspen Plus economic analysis tools.
The model supports early-stage investment decisions and process feasibility screening.
Design Feasibility
Column hydraulics were validated against flooding and pressure drop constraints.
Design is scalable for industrial deployment with minimal structural modifications.
Conclusion
The Aspen Plus simulation successfully demonstrates the feasibility of capturing CO₂ from syngas using a potassium carbonate (K₂CO₃) absorption-stripping system. By applying the Electrolyte NRTL property method and rate-based column modeling, the process achieves accurate representation of thermodynamics and mass transfer behavior. Economic evaluation confirms that the system is cost-effective and environmentally favorable for industrial-scale deployment. Overall, the model provides a strong foundation for further process optimization, integration, and scale-up within carbon capture and utilization frameworks.