Carbon Capture and Storage Hazard Investigation: Numerical Analysis of Hazards related to Dry Ice Bank Sublimation following Accidental Carbon Dioxide Releases

Abstract

Climate Change is caused by greenhouse gases such as CO₂. Worldwide increase in energy demand coupled with a continued reliance on fossil fuels have contributed to a significant increase in atmospheric levels of CO₂. Scenarios for stabilizing the emissions of CO₂ suggest mitigation actions including the deployment of Carbon Capture and Storage projects (CCS). One of the process steps consists in the transportation of the CO₂ to a storage location by buried pipelines. Any accidental release determined by failures is followed by a pressurized release of CO₂ with dry ice formation. Under specific conditions a dry ice bank will form contributing to atmospheric dispersion through superficial sublimation (Vianello et al., 2014). This study focuses on the importance of the bank sublimation emission to the near field dispersion of CO₂. The application of CFD techniques show that hazardous conditions exist over an area close to the source. Within 50 m from the pipeline the volumetric fraction of CO₂ still amounts to 7 – 10 % at 1.5 m above the ground, causing serious health effects on operators in a short time. In addition, a decrease in wind velocity coupled with an increase in both the ambient temperature and the intensity of solar radiation worsens the risk of health hazards. The danger persists for days after the accident given the slow dry ice bank sublimation process which becomes the dominant hazard source afterwards.