In the quest to mitigate climate change, carbon capture, utilization, and storage (CCUS) technology stands as a beacon of hope, promising to reduce CO2 emissions significantly. However, the presence of impurities in CO2 streams can pose substantial challenges, particularly when it comes to the safe and efficient transmission of CO2 through pipelines. A recent study published in You-qi chuyun, which translates to ‘Oil and Gas Storage and Transportation’ sheds light on the phase equilibrium characteristics of impurity-containing CO2 systems, offering crucial insights for the energy sector.
At the heart of this research is Naiya Xie, a researcher from the College of Pipeline and Civil Engineering at China University of Petroleum (East China) and the Shandong Key Laboratory of Oil & Gas Storage and Transportation Safety. Xie and her team developed an experimental setup to measure the phase characteristics of CO2 systems contaminated with nitrogen (N2), a common impurity. The setup leverages the compressibility difference between gas and liquid phases to calculate pressure at the bubbling and dew points, providing a comprehensive understanding of the system’s behavior over a wide temperature range, from -30℃ to 50℃.
The study compared experimental results with simulations generated by five state equations: the Peng-Robinson (PR) equation, GERG-2008 equation, Benedict-Webb-Rubin-Starling (BWRS) equation, Soave-Redlich-Kwong (SRK) equation, and Peng-Robinson-Stryjek-Vera (PRSV) equation. The findings revealed that the predictive accuracy of these equations diminishes as the N2 content increases, with varying performance across different temperature intervals.
“Our research highlights the importance of selecting the appropriate state equation based on the specific conditions and composition of the CO2 stream,” Xie explained. “This is crucial for ensuring the safety and efficiency of CO2 pipeline transmission, especially as we strive to advance CCUS technology.”
The implications of this research are far-reaching for the energy sector. As CCUS technology gains traction, the ability to accurately predict the phase equilibrium of impurity-containing CO2 systems will be vital for designing and operating safe and efficient pipeline networks. This study provides a roadmap for optimizing state equations, ensuring that they deliver reliable predictions across different temperature ranges and impurity concentrations.
For instance, the PR equation demonstrated enhanced accuracy in pressure prediction at both the bubbling and dew points below 0℃, making it an ideal choice for low-temperature applications. Conversely, the PRSV equation showed better performance above 0℃, offering a suitable alternative for higher temperature scenarios. These insights will enable engineers and operators to make informed decisions, minimizing risks and maximizing the potential of CCUS technology.
As the energy sector continues to evolve, the need for accurate and reliable predictions of CO2 system behavior will only grow. This research, published in You-qi chuyun, marks a significant step forward in our understanding of phase equilibrium characteristics, paving the way for future developments in the field. By optimizing state equations and tailoring them to specific conditions, we can unlock the full potential of CCUS technology, driving us closer to a more sustainable and low-carbon future.
