A low-energy chilled ammonia process exploiting controlled solid formation for post-combustion CO₂ capture.

Area of Science:

• Chemical Engineering
• Carbon Capture Technologies
• Process Optimization

Background:

• Ammonia-based processes are common for CO2 capture but face energy penalties.
• Conventional methods can involve solids in critical equipment, complicating operations.
• Reducing energy consumption and water usage is crucial for carbon capture viability.

Purpose of the Study:

• To develop and assess a new ammonia-based CO2 capture process utilizing solid ammonium bicarbonate formation.
• To compare the energy efficiency of the new process against a standard process without solid formation.
• To investigate the impact of solid phase formation on CO2 concentration and water consumption.

Main Methods:

• Development of a novel process incorporating precipitation, separation, and dissolution of ammonium bicarbonate.
• Rigorous performance assessment using the Specific Primary Energy Consumption for CO2 Avoided (SPECCA) index.
• Equilibrium-based process simulations and optimization algorithms to screen operating conditions.

Main Results:

• The new process achieved a SPECCA of 2.43 MJ/kg CO2, a 17% reduction compared to the standard process (2.93 MJ/kg CO2).
• Solid formation in a dedicated section kept absorption and desorption columns free of solids.
• CO2 wash section utilized solid formation to reduce wash water consumption.

Conclusions:

• Controlled solid formation in ammonia-based carbon capture significantly reduces energy penalty.
• The developed process offers a more energy-efficient alternative for CO2 capture from flue gas.
• Further research is needed to validate improvements and refine optimization accuracy.