CO₂ PROPERTIES AND EOS FOR PIPELINE ENGINEERING WORKSHOP – 11 NOVEMBER, YORK

Victor Emeka Onyebuchi, a PhD student of Cranfield University working on “Development of a Methodology for CO₂ Transport Implementation in a Region”

I am immensely grateful to UKCSSRC and my supervisor Prof Sai Gu for their support towards this one day workshop. I report on my experience at the workshop and how it has helped broaden my knowledge base. This workshop was held at the beautiful town of York.

The keynote presentation was by Professor Roland Span, Ruhr-Universität Bochum, Germany: “Thermodynamic Property Models for Transport and Storage of CO₂”. He reiterated that CCS is not a well known or already established technology, but rather a broad variety of technical options. This was followed by Russell Cooper of National Grid and the theme of his presentation was on “The Certainties and Uncertainties of CO₂ Transport and Storage”. Javier Rodriguez from the Process Systems Enterprise Ltd followed this with a presentation on “gSAFT: Advanced Physical Properties for Carbon Capture and Storage System Modelling”. Martin Trusler of Imperial College London was next with “Phase Behaviour and EoS Modelling of the Carbon Dioxide-Hydrogen System”. And Richard Graham, University of Nottingham ended the morning session with his presentation captioned “Understanding and Predicting CO₂ Properties for CCS Transport”.

A group discussions with academic presentations filled the afternoon where Solomon Brown, University College London presented on the “Impact of Equation of State on Simulating CO₂ Pipeline Decompression”. Xiaobo Luo, University of Hull made a presentation on the “Study of the Pipeline Network Planned in the Humber Region of the UK”. And Chris Wareing, University of Leeds presented on the “Numerical Modelling of Trans-Triple Point Temperature Near-Field Sonic Dispersion of CO₂ from High Pressure Dense Phase Pipelines”. It was suggested that researchers developing EoS should work closely with computation experts to minimise error.

One of the highlights of the workshop was during the presentation from Russell Cooper of the National Grid centring on “The Certainties and Uncertainties of CO₂ Transport and Storage” One of the issues highlighted was the need to adequately understand what is happening when CO₂ is being transported in a dense phase and it changes to a vapour phase resulting in the separation of component impurities. How quickly can the impurities mix again in such an upset to prevent a two phase fluid?

I found this particularly interesting, as part of my research on Process simulation of CO₂ pipeline Transport for flow assurance and energy analysis. I am investigating the effect of impurities, pipeline trajectory, gravity and frictional loses resulting from distance on pipeline repressurisation distance/ depressurisation trajectory.

I designed a potential CO₂ pipeline linking big emitters in Cambridgeshire area to a storage hub in Humberside covering a distance of 171km. The pipeline terrain crosses areas of land with high elevation, resulting in a sudden drop of pressure. Although, this drop in pressure does not result in the formation of a vapour phase, it was big enough to dip below 90bar which was my design basis to the critical pressure of 84.4 bar.

The result of this simulation shows that the pressure dip was not long enough (about 4km) to cause a phase split. However, if the dip in pressure is prolonged, it may result into the formation of a vapour phase which will cause the impurities to separate. The seperation triggers a whole lot of pipeline integrity issues such as corrosion if water is sufficiently present and embittlement if there is hydrogen.