(406g) Techno-Economic Optimization of a Solvent Absorption Process for CO2 Capture with 3d-Printed Intensified Packing

A significant challenge in implementing post-combustion CO₂ capture technologies for commercial use is the high cost. For a typical MEA process, costs can be upwards of 80 USD/ton¹. A majority of the cost for these solvent-based absorption processes can be attributed to the operation of the reboiler in the solvent regeneration process, which typically requires 3.7 MJ of steam for every kilogram of CO₂ due to a high heat of absorption, upwards of 100 kJ/mol CO₂². Although much work on developing novel solvents that have properties of higher capacity and lower heat of absorption has been done, considerable energy is still needed. Therefore, these systems should be operated as close as to their maximum thermodynamic efficiency for minimizing the energy requirements.

Heat generated from CO₂ absorption increases the temperature of the process, which in turn reduces the driving force for mass transfer². To reduce the temperature bulge, intercoolers between beds of the absorption tower^3,4 are often used to cool the solvent. Intercoolers, however, are incapable of maintaining an optimal temperature profile since they are implemented at discrete locations between the beds. A potentially better solution is to utilize 3d-printed intensified packings with internal channels for flow of a cooling medium, thus allowing for simultaneous heat and mass transfer within the process⁵. Such devices can help to operate the towers close to their maximum thermodynamic efficiency. In this work, we also investigate the application of the intensified device in the stripper. Instead of providing the entire heat at the reboiler, which creates a considerably non-uniform temperature profile across the tower, the intensified packing can help to operate the stripper at the optimal temperature profile.

Rigorous properties models are used in this work. Modified e-NRTL model is used as the thermodynamic model². Validated models for hydraulics, transport properties, heat transfer, and interfacial area are also implemented within the tower models. Optimal design and operation of the towers and the balance of the plant for the solvent-based CO₂ capture system are accomplished by solving a mixed integer non-linear programming problem by considering a flowsheet level model of the capture process⁶. The model is developed using the IDEAS modeling framework and considers a costing model to accurately evaluate the tradeoff between the capital and operating costs of the process⁷. The results show that the intensified packing when used in both absorber and stripper can lead to significant reductions in capture cost.

Acknowledgement

The authors graciously acknowledge funding from the U.S. Department of Energy, Office of Fossil Energy and Carbon Management, through the Carbon Capture Program.

Disclaimer

This project was funded by the Department of Energy, National Energy Technology Laboratory an agency of the United States Government, through a support contract. Neither the United States Government nor any agency thereof, nor any of its employees, nor the support contractor, nor any of their employees, makes any warranty, expressor implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof, or any of their contractors.

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