Optimization of cryogenic facilities for carbon dioxide capture

Cryogenic CO2 capture technologies represent a promising alternative for
large-scale decarbonization of industrial processes. This PhD thesis is dedicated to
the optimization of cryogenic facilities for carbon dioxide capture applied to
complete industrial cases such as cement or power production. The main objective
is to minimize the specific energy consumption of cryogenic processes while
maintaining a high CO2 recovery and purity. Indeed, despite their ability to produce
high-purity CO2 streams, cryogenic units remain strongly limited by the energy
demand related to deep refrigeration. Therefore, the optimization of such systems
is crucial to make them energetically and economically viable for industrial
deployment.
The work presents a detailed literature review and process analysis highlighting
the advantages and limitations of existing cryogenic technologies compared to
other capture routes. Then, several process configurations are investigated,
including a standalone cryogenic purification unit assisted with membrane, a hybrid
VPSA-CPU process, a sub-ambient membrane and a full cryogenic desublimation
system. Each configuration is modeled and simulated using process simulation
tools, and an optimization strategy is developed. Genetic algorithms are employed
to identify the optimal operating conditions leading to minimum energy
consumption and to evaluate the sensitivity of key design parameters.
The results show that the developed optimization framework allows a
significant reduction in energy demand compared to conventional reference
designs. For instance, the optimized cryogenic purification unit achieved energy
savings of up to 15% while ensuring more than 95% CO2 recovery and high purity.
Similar trends are obtained for the hybrid and desublimation schemes, confirming
the robustness of the methodology. The simulations are based on industrial flue gas
demonstrating the applicability of the proposed approach.
Finally, this thesis provides a comprehensive study on micro gas turbine for
improving the energy efficiency of cryogenic CO2 capture systems. The proposed
work contributes to the development of advanced and competitive capture
technologies capable of reducing the carbon footprint of heavy industrial sectors
while maintaining technical feasibility and reliability.