(2019) Journal of CO₂ Utilization_Reduction of Na and K contents in bio-heavy oil using micro-/nano-sized CO₂ bubbles

Kim Y., Oh J.-I., Zhang M., Lee J., Park Y.-K., Ho Lee K., Kwon E.E.

(Elsevier Ltd) Journal of CO2 Utilization ISSN: 22129820 Vol.34 Issue. Article No. DOI: 10.1016/j.jcou.2019.07.031

Co-combustion of bunker-C oil and bio-heavy oil for power generation provides a strategic way for mitigating the environmental burdens (climate change) due to the intrinsic carbon neutrality of bio-heavy oil. Prior to the co-combustion process, the high content of Na and K in heavy oil should be removed for the operational safety. Given that the washing process has been currently practiced for metal removal, it is desirable to develop the chemical-free washing process. Note that H₂SO₄ was commonly used during the washing process. To this end, this study laid great emphasis on the possible use of CO₂ for the washing process. To increase the removal efficiency of Na and K, this study particularly employed micro-/nano-sized CO₂ bubbles. To access the in-depth insights, a computational fluid dynamics (CFD) simulation was conducted prior to a lab-scale experimental work. The CFD simulation suggests that CO₂ bubbling expedited the mixability during the washing process. Also, the CFD simulation suggested that the CO₂ bubbling effects could be enhanced because the high viscosity of bio-heavy oil cancelled out the buoyancy force. A lab-scale experimental work was also in good agreement with the CFD simulation. In the presence of CO₂ bubbles, 80% of Na and K was removed when the volumetric ratio of water and bio-heavy oil was 8. Even under the volumetric ratio condition of 0.125, the metal removal efficiency was not substantially reduced. Thus, all experimental findings signify that metal removal by micro-/nano-sized CO₂ bubbling should be done by a cascade system. © 2019 Elsevier Ltd.

This work was supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20163010092290 ).