About the project
As part of the challenge to reduce the impact of global warming, pressurised pipelines are considered to be the most practical option for transporting captured CO2 from fossil fuel power plants for subsequent sequestration. A large release from a pipeline transporting fluids between the capture and injection facilities could have major accident potential due to the toxicity of CO2 at high concentrations.
The European CO2PipeHaz project was concerned with the modelling and validation of source terms and dispersion for potential major releases from CO2 pipelines. This was led by University College London, UCL, (UK) with the other partners being the University of Leeds (UK), INERIS (France), Gexcon (Norway), Demokritos (Greece), Dalian University of Technology, DUT, (China) and the Health and Safety Laboratory, HSL, (UK).
Main objectives
The CO2PipeHaz project is focused on the development and validation of mathematical models and decision support tools for hazard assessment of CO2 transportation pipelines to be employed as an integral part of the CCS chain. The main objectives as outlined in the Description of Work (DoW) are to:
- Define an optimum level of impurities in the CO2 stream based on safety, environmental and economic analysis;
- Develop a computationally efficient multi-phase heterogeneous outflow model for the accurate prediction of the time-variant release rate and the physical state of escaping CO2 following pipeline failure, based on a reliable equation of state for CO2 and CO2 mixtures;
- Develop multi-state dispersion models for predicting the subsequent concentration of the released CO2 as a function of time and distance from the release, both in terms of a detailed near- and far-field modelling capability;
- Conduct small- and large-scale experimental validations of the models developed;
- Provide a detailed understanding of the hazards presented by CO2 releases through experimentation and, using the data generated, validate the outflow and dispersion models developed;
- Embody the understanding and predictive capabilities developed in decision support tools, assessing and improving existing safety, risk assessment methods, tools for CO2 pipeline application, and producing refined best practice guidelines; and
- Demonstrate the usefulness of the tools developed through their application to possible CO2 pipeline designs.
Work packages
WP1: Accidental discharge phenomena
- WP1.1 - CO2 Composition and cost-benefit analysis
- WP1.2 - Phase equilibrium and thermodynamic and transport properties
- WP1.3 - Multi-phase heterogeneous discharge model and emergency isolation
- WP1.4 - Near-field dispersion model
- WP1.5 - Far-field dispersion model
WP2: Experimental data
- WP2.1 - Small-scale experimental investigation
- WP2.2 - Industrial scale experimental investigation
WP3: Decision support
Gexcon's involvement
Gexcon coordinated the efforts related to WP1.5 on the modelling of far-field dispersion of carbon dioxide resulting from accidental pipeline releases, including the importance of terrain and the wind field on the dispersion behaviour.
Far-field dispersion modelling used computational fluid dynamics (CFD) and methods were developed to import realistic terrain data into the FLACS software. To model the behaviour of solid CO2 particles formed in the near-field jet, a Lagrangian particle-tracking model for multiphase dispersion has been successfully implemented in FLACS. The model can predict the spatial and temporal evolution of the CO2 concentration during pipeline release scenarios. The model takes into account the two-way coupling effects between the continuous gas phase and the dispersed particle phase, and also particle sublimation and deposition. The validation of both FLACS and CFX models against results from the small-scale experiments of INERIS and the large-scale experiments of DUT was successfully carried out.
Publication
