CO2 transport in supercritical state: Nikiski, Alaska pipeline study

Abstract

Carbon dioxide (CO₂) in the supercritical state, being denser yet less viscous, is suitable for long-distance transportation. Despite this well-known principle, implementing an operational scheme with appropriate inlet pressure and mass flow rate for supercritical CO₂ (srCO₂) transportation is challenging due to the complex interplay among state variables, fluid properties, pipeline dimensions and materials, and the intricate boundary and ambient conditions surrounding the pipeline. This paper utilizes PIPESIM software to conduct a feasibility study of srCO₂ transportation over a 10-mile-long model pipeline in the Cook Inlet region of Alaska, USA. The study aims to understand the limitations of operational parameters and develop a scheme for selecting feasible parameters for srCO₂ transportation. Considering geographic location, elevation profiles, and ambient conditions, the simulations calculated pressure and temperature profiles, erosion kinetics, and fluid states for various conditions derived from a combinatorial set of pipeline diameters ranging from 11 to 16 in, inlet pressures between 1,400 and 1,900 psia, and mass flow rates from 10 to 275 lbm/s, with an inlet temperature of 200 °F. The major findings indicate that larger pressure losses are expected in smaller pipelines that are well-insulated and/or operated at lower inlet pressures. Turbulent flow is more likely to occur in smaller pipelines and at higher mass flow rates, potentially altering the state of the transported fluid. The parametric modeling results provide a scenario-driven approach to determining a feasible range of mass flow rates, pipeline inner diameters, and inlet pressures for srCO₂ transportation. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.