2 minute read
Sustainable steel solutions for CO2 transport and storage
The European Green Deal and the de-carbonisation efforts of hard-to-abate sectors have put the topic of Carbon Capture and Storage (CCS) high on the agenda of policy makers, industry and society. Various CCS pilot projects are on the radar screen, aiming to capture CO2 at (for example) blast furnaces, thermal power plants and cement factories, and store the CO2 in depleted offshore reservoirs or aquifers. In addition to liquid CO2 transport by vessels, worldwide deployment of CCS will require a vastly expanded network of CO2 transport pipelines. At OCAS, we are designing new steel grades to build the backbone for these de-carbonisation efforts.
INTEGRITY OF CO2 PIPELINES: A TOUGH CHALLENGE!
Challenges related to the design of CO2 transport pipelines are well documented and include the risk of low temperatures following Joule-Thompson decompression, and the susceptibility of sweet corrosion in the presence of water and impurities. By far the biggest challenge, however, is the fracture control strategy. Indeed, the thermodynamic properties of carbon dioxide are distinctly different than those of conventional natural gas. This imposes much more stringent requirements on the toughness of the pipeline steel. At OCAS, we have extensive experience in toughness testing of high-strength pipeline steels, including instrumented Charpy V-notch experiments and Battelle Drop Weight Tear Testing. In addition to these standardised fracture tests, we are investigating the crack arrest capabilities of pipeline grades by means of Dynamic Tear Testing. Moreover, we have developed a home-grown numerical toolkit based on computational fracture mechanics, which allows us to simulate crack initiation, propagation and arrest in CO2 pipelines. This combined experimental/numerical approach allows the specifications for new steel solutions for Carbon Capture and Storage to be derived. Finally, our metallurgical department designs the corresponding metallurgies to produce coil skelp, plate skelp and crack arrestors.
In addition to dense phase CO2 transport pipelines, some CCS projects require pressure vessels to store and transport liquid CO2. Due to the stringent process conditions for liquid CO2, with pressures
Our new steel solutions enable the safe transport of dense phase CO2 through pipelines. At OCAS, we feel we are truly inventing smarter steels for people and planet.
Steven Cooreman
between 5 and 25 bars and temperatures down to -60°C, conventional carbon steels cannot be used. The pressure vessels need to be constructed in expensive, nickelalloyed high-strength steel. OCAS is working on a breakthrough project to tailor steels to provide a cost-competitive alternative solution for liquid CO2 pressure vessels. Thanks to the extraordinary combination of high-strength, low-temperature toughness and lean alloying, such steels can become a game-changer for CCS projects.
Today, calculation of the thermal profile for upcoming production cases should be possible before the production starts. This will minimise the number of expensive trials that are required to optimise process parameters.
Jan Rens & Özlem Esma Ayas Güngör
