Effect of water and nitrogen impurities on CO2 pipeline transport for geological storage

Abstract

Abstract Carbon dioxide capture and storage (CCS) technology is regarded as one of the most promising emission reduction options for the mitigation of climate change and global warming. The technology of CCS involves a process of capturing CO2 from industrial and energy-related sources (such as a power plant), transporting it from its sources to the storage sites, and storing it in the geological structures for long-term isolation from the atmosphere. Although the technologies for capture and storage of CO2 have been globally investigated and verified, the development of transport infrastructure is still in the initial stage except some typical cases. Especially, the effect of impurities on transport and injection is not clearly resolved yet. Up to now, process design researches for CO2 transport and storage have been carried out mainly on pure CO2 cases. Unfortunately the real captured CO2 mixture contains many impurities such as N2, O2, Ar, H2O, SOx, H2S. Some impurities can change the thermodynamic properties and then significantly affect the compression, purification, transport and injection processes. Among them, N2 can affect the CO2 transport process by its low boiling point. In other words, a small amount of nitrogen can make change flow conditions from single phase flow to two-phase flow. And a small amount of water in CO2 stream can trigger the clogging problem due to formation of hydrate. In this paper, a numerical evaluation of process design model was carried out. We compared and analyzed the relevant equations of state for CO2-N2 mixture. To quantitatively evaluate the predictive accuracy of the equation of the state, we compared numerical calculation results with reference experimental data. In addition, optimum binary parameters to consider the interaction of CO2 and N2 molecules were suggested based on the mean absolute percent error. With regard to CO2-H2O mixture transport, the hydrate formation possibility was analyzed based on the hypothetical scenario in republic of Korea. To understand the physical behavior of CO2-imputities mixture, experimental investigations are necessary. We made an experimental facility which is consist of high pressure compression module, liquefaction module, mixing module, cooling module and transport test section. The flow behavior such as single phase and twophase pressure drop of CO2-N2 mixture pipeline transport was experimentally analyzed. Based on this experimental data, we may suggest some design guideline for CO2 pipeline transport.