Study on transient characteristics of shutdown and restart of supercritical CO2 pipeline containing impurities
To study the change law of temperature,pressure,and phase inside the supercritical CO2 pipeline after shutdown,taking a domestic CO2 pipeline as the research object,the OLGA software was used to conduct the transient numerical simula-tion of shutdown and restart,and the influence of different operating conditions and working medium on the pipeline shutdown and restart process was explored.The results show that when remaining the phase state and downstream user flow rate un-changed,the larger the flow rate,the shorter the maximum shutdown time,and the phase transition occurs first at the mid-front part and high points of the pipeline.Under the same operating conditions,the existence of non-polar impurities such as H2 and N2 can cause the phase envelope of CO2 to move upwards,reducing the maximum shutdown time,while the polar impurities such as H2S and CO can cause the phase envelope of CO2 to move downwards,increasing the maximum shutdown time.Dur-ing the shutdown and restart process,if the density of contained impurities is less than that of pure CO2,the time required for pipelines containing this type of impurities to restore the stable operation status is shorter than that of pure CO2 pipeline.The research results can provide guidance and suggestions for related organizations to develop the CO2 pipeline design and safety shutdown plans.
OLGAimpure CO2shutdown and restartsafety shutdown time
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