Pipeline Transportation of Carbon Dioxide Containing Impurities
12 Atmospheric Dispersion of CO2 Containing Impurities
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- Ris (Zotero)
- Reference Manager
Dispersion modeling of CO2 release scenarios needs to be included as part of a quantitative risk analysis when designing or operating CO2 pipelines, as discussed in Chapter 11. Analysis of release conditions, and subsequent dispersion, can help evaluate factors that increase the risk of a loss due to physical or toxicological impacts (e.g., emergency shutdown valve spacing). Simulation of a CO2 release presents new challenges when compared to simulation of natural gas releases. One of these challenges is the dispersion characteristics of a CO2 pipeline release to atmosphere. Although a CO2 release does not pose an explosion risk as with a natural gas pipeline, the released CO2 disperses as a nonflammable dense (i.e., heavier than air) cloud that can potentially create hazardous conditions for some distance from the release site. Dispersion modeling techniques need to address the dense-gas specific behavior of a CO2 release, for example, gravity slumping that leads to increased dispersion and air entrainment in the cross-wind direction. As CO2 pipelines are a relatively young technology, compared to hydrocarbon pipelines, the dispersion modeling techniques are still being refined to account for CO2-specific phenomena such as solid particle (dry ice) formation in the cold depressurized jet.
Risk analysis of CO2 dispersion must address the potential toxic or asphyxiant hazards posed by a CO2 cloud, as well as the potential toxic hazards posed by any impurities (e.g., H2S, NH3, CO) that are mixed within the CO2 cloud. The CO2 release scenarios that should be simulated are dependent on the risk analysis application; a new-construction risk analysis would need to account for accidental rupture, puncture of the pipeline, or equipment failure, whereas a maintenance risk analysis could require that dispersion modeling be performed for a planned pipeline depressurization (blowdown).
The following chapter provides a discussion on the release hazards specific to CO2 pipelines, a brief background on atmospheric dispersion and pipeline release dynamics, and an introduction to dispersion modeling techniques. Atmospheric dispersion results from simulating controlled blowdowns of a CO2 pipeline with impurities as well as results from modeling a full pipeline rupture are also presented.