Study on water hammer characteristics and protection measures of supercritical/dense CO2 pipelines

Abstract

Pipeline transportation under supercritical and dense phases is commonly adopted for carbon dioxide (CO₂) long-distance transportation due to its high transportation capacity and low energy consumption. When valves are accidentally shut off in CO₂ pipeline systems, there might exist phase transitions or local overpressure due to water hammer effects. In this paper, a rapid transient method is proposed by improved characteristic line algorithm to simulate dynamic behaviors of water hammer scenarios, and characteristics of phase transitions in CO₂ pipelines under water hammer scenarios are investigated. It was found that time-consuming by proposed method is about 4–10 times faster than that by implicit difference methods. Elevation differences have significant effects on operating pressure of CO₂ pipelines under water hammer scenarios. CO₂ fluids in downward sloping pipelines with a large drop is more likely to undergo phase transitions due to water hammer effects. Corresponding downstream valve can be closed simultaneously to extend fluid phase transitions in pipelines when a upstream valve in CO₂ pipelines is accidentally shut off.