»
»
Energy Transition
RUB was verified and found to be accurate. The obtained results were the basis to investigate the practical application of desublimation as a carbon capture method. One such application was found in bio-LNG production. Biofrigas with its headquarters in Göteborg, Sweden, offers small scale, container based, liquefaction plants for bio-LNG production from biogas or biomethane. When biogas comes out of the digestors, it contains too much CO 2 to put directly into LNG. Kelvion supplied desublimators for a full-scale pilot project, which was very succesful. Obtained results:
• Concentration of CO 2 in the specified range of bio- LNG
• Cycle times confirmed for continuous operation
• Morphology of crystals confirmed desublimator process design
• Required CO 2 capturing capacity of desublimators confirmed
Direct air capture For direct air capture( DAC) two main groups of technologies exist. There are liquid-based systems and solid capture technologies. In a liquid-based system, the air is brought into contact with a liquid that contains a chemical solution and removes the CO 2 from the air. In another step of the process, the liquid must be regenerated and the CO 2 released for further processing and which can then be stored underground for instance in geological formations. Big amounts of air are being processed, and these will be large-scale installations. The principle of the‘ air contactor’ or‘ contact tower’, in which a large contact area between air and a liquid must be provided, shows many similarities to a wellestablished technology in industry: the cooling tower. In both a cooling tower and a contact tower, the fluid is divided and sprayed from the top over a polymeric fill structure. The polymeric fill enlarges the contact area and contact time with air. The air is sucked through the fill by using a large fan which is installed in a fan hood on the top of the tower. Different fill structures can be provided. The finer the structure, the higher the efficiency. However, a finer structure is also more sensitive to fouling because of dust and particles from the air, or, in the case of DAC, precipitation material. An optimisation must be made. An important aspect that distinguishes the Kelvion Polacel cooling tower from other types is the stainless steel, bolted construction. It enables ultra-fast onsite erection or even offsite pre-assembly in complete cells, or building blocks which are then hoisted easily on the basins to minimise site work.
Figure 10: Kelvion Polacel cooling tower.
Figure 9: Process diagram direct air capture [ 3 ].
Conclusion The journey towards effective carbon capture and storage( CCS) is marked by significant technological advancements and engineering challenges, particularly in the realm of heat transfer. This article has explored three prominent CCS methods: amine-based absorption, cryogenic carbon capture, and direct air capture, each presenting unique heat exchanger challenges. Amine-based absorption, a well-established method, relies heavily on efficient heat exchangers for solvent regeneration and energy optimisation. Innovations such as the Groovy fin and DIESTA tube have significantly improved heat transfer efficiency, reducing the size and cost of installations. Cryogenic carbon capture through desublimation offers a novel approach, with successful pilot projects demonstrating its potential. The development of accurate mathematical models and practical applications, such as in bio-LNG production, highlight the method’ s viability. Direct air capture( DAC) technologies, both liquid and solid-based, require large-scale installations with optimised heat transfer systems. The similarities to cooling tower technology and the use of advanced materials and designs underscore the importance of efficient heat exchangers in these systems. As the demand for scalable and sustainable CCS solutions grows, continuous innovation in heat exchanger technology will be crucial. By addressing the heat transfer challenges inherent in these methods, we can enhance the efficiency and effectiveness of carbon capture, contributing to a more sustainable future.
References
[ 1 ]“ Power 101: Flue Gas Heat Recovery in Power Plants, Part I” POWER Magazine, 1 April 2010. [ Online ]. Available: https:// www. powermag. com / power-101-flue-gas-heat-recovery-inpower-plants-part-i.
[ 2 ] N. Mirza en D. Kearns,“ State of the art: CCS Technologies 2022,” Global CCS Institute, 2022.
[ 3 ] D. Hospital-Benito, C. Moya, M. Gazzani en J. Paloma,“ Direct air capture based on ionic liquids: From molecular design to process assessment,” Chemical Engineering Journal, pp. Volume 468, 2023, 143630, 2023.
About the author
Roy Niekerk has more than 22 years of experience in heat exchangers, both in suppliers as well as in an oil & gas major. He is now VP Hydrogen & New Energies within Kelvion.
www. heat-exchanger-world. com Heat Exchanger World April 2025
27