CO2 Transportation with Pipelines - Model Analysis for Steady, Dynamic and Relief Simulation

Abstract

“Carbon dioxide or CO₂ capture and storage” (often defined by its acronym CCS) is the term used to describe a set of technologies aimed at capturing carbon dioxide emitted from industrial and energy-related sources before it enters the atmosphere, by compressing and injecting it underground in secure geological formations. The scope would be the mitigation of greenhouse effects and the reduction of related global warming and climate changes. A large number of papers have been devoted to this topic, Some recent publications, also in this series, has been devoted to the risk assessment of CO₂ relief (Vianello et al. 2012) and overall risk analysis of CO₂ transportation (Samadi et al. 2012). It is not the aim of this paper to discuss the effectiveness of the technology but to only focus on the transportation of CO₂ from production points to the storage location. The only feasible way of performing this task is the use of pipelines of high-capacity. Though carbon dioxide is not very poisonous, however its relief in large quantities combined with its density higher than air could fill populated regions with large dangerous effects. This paper analyses the thermodynamic methods required for a reliable simulation of steady state as the initial requirement for the subsequent calculation of relief conditions (flow rate, pressure and temperature) as a preliminary critical step to the calculation the dispersion effects. The availability of reliable calculation methods of the most relevant CO₂ properties (enthalpy, entropy, density and viscosity) which play a key role in the fluid-dynamic calculations required by for safe and cost-effective pipeline design. These projects are usually carried out by means of commercially available process simulators (HYSYS, AspenPlus, ChemCad, etc.) and fluid-dynamics simulators (OLGA, LedaFlow, etc.). The selection of convenient equations of state and numerical methods is a key factor in engineering design as well as in the identification of possible hazards scenarios and the calculation of consequences. In summary the requirements of a reliable and high-precision simulation tool for overall engineering design are presented.