An Open Source Tool for Calculating CO2 Pipeline Decompression Wave Speed

This paper describes a simplified calculation method for pipeline decompression wave speed based on a rigorous equation of state for pure CO 2 as well as mixtures with significant impurities.Calculations are performed assuming homogeneous equilibrium for the estimation of the speed of sound in the two-phase region and calculations are performed along an isentropic decompression path.These calculations are important for the design of pipelines and can be used to estimate the required wall thickness and/or material toughness when combined with e.g. the Battelle two curve method, thereby ensuring that a potential running ductile fracture is arrested.The calculations are validated against available literature data and is offered as an open source tool.For pure CO 2 at supercritical conditions the model results match experimental results very well, whereas for the dense liquid phase the pressure plateau in the decompression wave speed curve is over-predicted.For CO 2 with impurities the model calculations generally match experimental data, except for the experiment with a significant fraction of hydrogen and for the experiment with the highest amount of impurities of approx.6%.In these two cases the pressure plateau is under-predicted.