Finite Element Based Fatigue Life Evaluation of Anthropogenic CO<sub>2</sub> Pipeline Containing an Inner Defect

Abstract

The great effort for reducing emissions of CO2 to atmosphere will inevitably involve the carry-out process of Carbon Capture and Storage(CCS), a novel plan which intends to capture and store anthropogenic CO2 produced at many existing industrial sources, such as power stations and petrochemical works. In particular, anthropogenic CO2 pipeline transportation from the energy plant to the remote sequestration area(both onshore and offshore) is a fundamental issue regarding the feasibility of applying the CCS technology. CO2 pipelines have been in operation in USA, Europe and North Africa for almost three decades. However, the technical challenges for pipelines transporting CO2 due to the relevant effects of different impurities coming from flue gases, are still needed to get people to take up, especially for China which is focusing on the roll-out of CCS. This paper will address a FE-based method which can assess residual life of a supercritical CO2 transmission pipeline containing an inner defect induced crack. Specifically, a portion of welded round steel pipeline is selected as the object of our analysis and an ANSYS finite element procedure is generated to simulate the stress state of an element volume along the radial direction and hence to calculate the effective stress due to the effects of crack closure. Afterwards, combining the effective stress we get in the above numeric analysis, the Paris equation is modified to build an integral analysis method for the residual life evaluation of CO2 pipeline. Lastly, in order to verify the validity of the proposed method, a pipeline example in a published paper is used as the benchmark model, the full-scale test results of which are compared with those from our method. Based on this, a section of CO2 pipeline, with an initial defect (assumed as a crack source), is analyzed and its residual life is evaluated by using the presented method. The analysis of numerical results indicates that the method presented in this paper can give us a valuable reference to life-evaluation for CO2 pipeline in CCS.