Source strength and dispersion of CO2 releases from high-pressure pipelines: CFD model using real gas equation of state

Abstract

Transportation of CO2 in high-pressure pipelines forms a crucial link in the ever-increasing application of Carbon Capture and Storage (CCS) technologies. An unplanned release of CO2 from a pipeline presents a risk to human and animal populations and the environment. Therefore it is very important to develop a deeper understanding of the atmospheric dispersion of CO2 before the deployment of CO2 pipelines, to allow the appropriate safety precautions to be taken. This paper presents a two-stage Computational Fluid Dynamics (CFD) study developed (1) to estimate the source strength, and (2) to simulate the subsequent dispersion of CO2 in the atmosphere, using the source strength estimated in stage (1). The Peng-Robinson (PR) EOS was incorporated into the CFD code. This enabled accurate modelling of the CO2 jet to achieve more precise source strength estimates. The two-stage simulation approach also resulted in a reduction in the overall computing time. The CFD models were validated against experimental results from the British Petroleum (BP) CO2 dispersion trials, and also against results produced by the risk management package Phast. Compared with the measurements, the CFD simulation results showed good agreement in both source strength and dispersion profile predictions. Furthermore, the effect of release direction on the dispersion was studied. The presented research provides a viable method for the assessment of risks associated with CCS.

Study of the consequences of CO2 released from high-pressure pipelines

“…On the other hand, dispersion modelling is space-consuming, requiring a large enough domain to allow the spread of the pollutant without the results being adversely affected by the boundary condition. For an overall CFD model including both the depressurisation and dispersion domains, the required computing time would be unacceptably long (Liu et al, 2014;Novembre et al, 2006). Therefore the problem was divided into three parts, as shown in Fig.…”

“…This requires precise modelling of the thermodynamic properties of CO 2 using a 'real gas' EOS (Liu et al, 2014). The first real gas EOS was developed by van der Waals in 1873 (van der Waals, 1873).…”

“…Meanwhile, in the vicinity of the exit, an under-expanded jet flow exits from the orifice into the ambient with very high momentum. The prediction of highly transient high-speed flow requires a dense mesh and a very small time step (Liu et al, 2014;Novembre et al, 2006). On the other hand, dispersion modelling is space-consuming, requiring a large enough domain to allow the spread of the pollutant without the results being adversely affected by the boundary condition.…”

“…In the CCS chain, transportation of CO 2 in highpressure pipelines from source to storage location constitutes an important link, especially when transporting large quantities of CO 2 over long distances. It is expected that extensive networks of CO 2 pipelines would be required in the near future with the growing application of CCS (Liu et al, 2014;Mazzoldi et al, 2012).…”

Modelling ruptures of buried high pressure dense phase CO 2 pipelines in carbon capture and storage applications—Part I. Validation

“…Further, the CFD model appears to under-predict the spreading rate of the jet. Liu et al (2014) (Woolley et al, 2013) and the COOLTRANS research programme (Wareing et al, 2014a). previously considered the validation of FLACS and ANSYS-CFX in the far-field for this application, using Leeds predictions for the near-field, albeit again modified for input into such commercial software.…”