(86k) Guidelines for Designing Amine-Based CO2 Capture Systems Onboard LNG Fuelled Ships

With the ever-growing concerns on the rise in Global Greenhouse (GHG) emissions, the International Maritime Organization has set timelines to reduce the GHG contribution of the maritime industry. Liquified Natural Gas (LNG) has emerged as a fuel of great interest, as it has 20-30% lower CO₂ emissions and negligible SOx emissions. Hence, a surge is expected in the manufacturing of LNG run ships (Al Baroudi et al., 2021). However, this alone is insufficient to meet the eventual target of 50 % reduction (with 2008 as benchmark). Therefore, Carbon Capture and Concentration (CCC) must still be studied and pursued as a potential remedy.

The existing literature has several studies on CO₂ capture onboard LNG fuelled ships. (Luo & Wang, 2017) and (Lee et al., 2021) studied amine-based aborption for engines of 15 MW and 18.2 MW. (Feenstra et al., 2019) studied both PZ and MEA as a solvent for a 3 MW ship. (Awoyomi et al., 2020) evaluated NH₃ based absorption as a technology for CCC for a 8.8 MW engine. (Oh et al., 2022) performed simulation studies on membrane-based capture for an 18.2 MW main engine. Our previous simulation studies on a 47,000 DWT MR Tanker suggested that amine-based absorption is the cheapest option for maritime capture.

All the above studies focused on specific ships, engines, or exhaust gas conditions only. To enhance the practical utility of their works, we develop a spectrum of designs for several combinations of flue gas conditions (flow rate, temperature, composition), maximum CO₂ storage time, and voyage length for LNG run ships. A rate-based model was simulated in Aspen Plus, and uses models/correlations, and numerical parameters were validated against the pilot plant data from (Notz et al., 2012) in our previous study. The design comprises the selection of key variables for separation, e.g., the absorber and regenerator column sizing, solvent flow rate, as well as selection of optimal CO₂ storage conditions. Additionally, the best configuration for cold energy integration to minimize the extra power demand for CO₂ compression and liquefaction is also assessed. The design is based on 90% recovery of CO₂ from the effective flue gas to be processed, including emissions stemming from extra fuel burnt for the fulfilment of the energy deficit for capture and the power demand for CO₂ compression. To this end, a novel non-iterative approach to calculate effective flue gas to be processed as a function of the flue gas conditions under optimized design conditions is also developed. Lastly, volume and weight losses incurred as a result of the installation of the capture unit are also presented.

References:

Al Baroudi, H., Awoyomi, A., Patchigolla, K., Jonnalagadda, K., & Anthony, E. J. (2021). A review of large-scale CO2 shipping and marine emissions management for carbon capture, utilisation and storage. Applied Energy, 287, 116510.

Awoyomi, A., Patchigolla, K., & Anthony, E. J. (2020). Process and Economic Evaluation of an Onboard Capture System for LNG-Fueled CO2 Carriers. Industrial & Engineering Chemistry Research, 59, 6951-6960.

Feenstra, M., Monteiro, J., van den Akker, J. T., Abu-Zahra, M. R. M., Gilling, E., & Goetheer, E. (2019). Ship-based carbon capture onboard of diesel or LNG-fuelled ships. International Journal of Greenhouse Gas Control, 85, 1-10.

Lee, S., Yoo, S., Park, H., Ahn, J., & Chang, D. (2021). Novel methodology for EEDI calculation considering onboard carbon capture and storage system. International Journal of Greenhouse Gas Control, 105, 103241.

Luo, X., & Wang, M. (2017). Study of solvent-based carbon capture for cargo ships through process modelling and simulation. Applied Energy, 195, 402-413.

Notz, R., Mangalapally, H. P., & Hasse, H. (2012). Post combustion CO2 capture by reactive absorption: Pilot plant description and results of systematic studies with MEA. International Journal of Greenhouse Gas Control, 6, 84-112.

Oh, J., Anantharaman, R., Zahid, U., Lee, P., & Lim, Y. (2022). Process design of onboard membrane carbon capture and liquefaction systems for LNG-fueled ships. Separation and Purification Technology, 282, 120052.