Numerical simulation of coupling characteristics between fracture propagation and internal decompression of CO2 pipelines
CHEN Lei1,2,HU Yanwei1,YAN Xingqing1,YU Shuai1,LIU Zhenxi1,QIAO Fanfan1,YU Jianliang1,CHEN Shaoyun1,2

1.School of Chemical Engineering, Dalian University of Technology; 2.School of Chemical Engineering and Technology, Xinjiang University

CO2 pipeline safety, bidirectional fluid-structure interaction, crack propagation angle, crack propagation velocity

DOI: 10.6047/j.issn.1000-8241.2024.05.006


【目的】管道是CCUS(Carbon Capture, Utilization and Storage)技术最主要的输送工具,研究其动态断裂扩展规律显得尤为重要。全尺寸断裂实验的准备周期长、技术门槛高、资金投入大、不确定因素多,严重制约了CO2输送管道断裂扩展过程中管道断裂与管内减压规律的研究。【方法】基于双向流固耦合技术,使用Frotran语言开发了用户自定义子程序来描述流体减压特性,通过材料性能实验构建管道材料的GTN(Gurson-Tvergarrd-Needleman)本构方程,在ABAQUS/Explicit软件中构建了超临界CO2输送管道裂纹动态扩展与管内减压的流固耦合数值模型,用于开展管道裂纹扩展特性与管内介质减压规律的协同分析,通过Python脚本完成模拟结果批量处理。【结果】数值模拟得到的管道断裂形态与实验结果非常相似;管道断裂速度在管内介质溢出后呈现快速上升并逐渐稳定的趋势,最终稳定在约225m/s;裂纹尖端张开角(Crack Tip Opening Angle, CTOA)呈现先减小后增大的趋势,最终稳定在约7.22°;CO2在裂纹扩展尖端附近仍保持高压状态,其在裂纹尖端处降压膨胀所形成的饱和蒸汽加大了管道止裂难度。【结论】通过开展仿真模拟可以准确复现全尺寸断裂实验,在揭示管道断裂过程中CTOA、裂纹尖端及开裂区压力演变历程等诸多实验无法捕捉的参数方面具有优势。所构建的CO2流固耦合数值模型有助于对CO2输送管道断裂特性开展深入分析,可为不同管道尺寸及气体参数下的CO2管道安全控制评估提供参考。(图 12,参[19]
[Objective] Pipelines serve as the primary transportation means for Carbon Capture, Utilization and Storage (CCUS) technology, so it is vital to study their dynamic fracture propagation laws. However, the prolonged preparation periods, technical complexities, substantial financial investments, and numerous uncertain factors associated with full-scale fracture experiments significantly impede progress in studying pipeline fracture and the internal decompression laws during CO2 transmission pipeline fracture propagation. [Methods] Leveraging bidirectional Fluid-Structure-Interaction (FSI) technology, a user-defined subprogram was developed with Frotran to delineate fluid decompression characteristics. A Gurson-Tvergarrd-Needleman (GTN) constitutive equation for pipes was established through an experiment focusing on material properties. Moreover, a fluid-structure interaction numerical model was constructed in ABAQUS/Explicit software to simulate supercritical dynamic crack propagation and internal decompression of CO2 transmission pipelines. This model was subsequently used for a collaborative analysis of pipeline crack propagation characteristics and internal medium decompression laws. The simulation results were further processed in batches through Python scripts. [Results] The pipeline fracture morphology from numerical simulation closely mirrored the experimental results. The crack propagation velocity showed an initial rapid increase after medium spillage, followed by gradual stabilization, and finally reaching approximately 225 m/s. The crack tip opening angles initially decreased, then increased before stabilizing at around 7.22°.CO2 remained under high pressure near the crack propagation tip, while saturated steam formed through decompressional expansion at the crack tip worked against crack arrest. [Conclusion] This study demonstrates the accurate replication of full-scale fracture experiments by simulation and showcases the advantages of simulation in revealing many parameters that can hardly be captured through experiments, such as crack tip opening angles, as well as pressure evolution at crack tips and fracture zones during pipeline fractures. The constructed numerical model of CO2 fluid-structure interactions facilitates an in-depth analysis of CO2 transmission pipeline fracture qualities. The simulation results can serve as references for safety control assessments of CO2 pipelines with varying dimensions and gas parameters. (12 Figures, 19 References)