含杂质超临界CO2输送管线流体相行为及腐蚀机理

As one of the key technologies for reducing CO2 emissions worldwide, there is an urgent need to accelerate the commercial deployment of carbon capture and storage (CCS).Accordingly, the transmission of supercritical CO2 by pipelines will be necessary if large volumes of captured CO2 are to be stored in geological formations. For the supercritical CO2 fluid, the interaction between various kinds of impurity components complicates the corrosion mechanism of the pipelines. The internal corrosion of pipelines containing impurities will be a challenge of pipeline integrity management and an urgent scientific problem to be solved in the field of corrosion research. In this project, based on the analysis of phase behavior and water chemistry characteristics, the thermodynamic model is established to expound the relationship between impurities and precipitated water phase as well as water chemistry characteristics. In order to clarify the corrosion synergistic effect mechanism among the impurity components on the corrosion of pipeline steels, corrosion simulation tests, in-situ electrochemical tests under high pressure and microstructure characterization of corrosion scales are employed to reveal the growth mechanism of corrosion scale and electrochemical corrosion mechanism. It is expected to illustrate the essential corrosion mechanism of supercritical CO2 transmission pipeline containing impurities. On this basis, the corrosion model of supercritical CO2 pipeline containing impurities is established eventually. This research will provide the experimental and theoretical basis for the establishment of quality specifications of supercritical CO2 fluid, and provide the scientific basis and technical support for corrosion prediction and integrity management of supercritical CO2 transmission pipeline in CCS.

碳捕集与封存（CCS）作为全球CO2减排的关键技术之一，其规模化和商业化应用需要大规模地建设超临界CO2输送管线，在超临界CO2流体中杂质组分的相互作用决定了其腐蚀机理的复杂性，该类管线的内腐蚀既是工程领域管道完整性管理面临的难题，又是腐蚀研究领域亟待解决科学问题。本项目以CCS过程中含杂质的超临界CO2输送管线为研究对象，通过相行为和水化学特性分析，建立超临界CO2-H2O-杂质体系流体热力学模型，阐述杂质与水相析出及水化学特性的关系。通过腐蚀模拟实验、高压原位电化学测试和腐蚀膜的微观表征，揭示超临界CO2输送管线钢腐蚀膜生长演化机制及腐蚀电化学机理，同时澄清杂质组分之间对管线钢腐蚀的协同作用机理，从本质上阐明含杂质超临界CO2输送管线的腐蚀机制。在此基础上，建立含杂质超临界CO2输送管线的腐蚀模型，从而为CCS中含杂质超临界CO2输送管线的腐蚀预测和完整性管理提供科学依据和技术支撑。

随着化石能源消耗的增加，二氧化碳的大量排放引起的温室效应和全球变暖已成为全球最受关注的问题之一。碳捕集与封存（CCS）作为全球 CO2 减排的关键技术之一，其规模化和商业化应用需要大规模地建设超临界 CO2 输送管线，在超临界 CO2 流体中杂质组分的相互作用决定了其腐蚀机理的复杂性，该类管线的内腐蚀既是工程领域管道完整性管理面临的难题，又是腐蚀研究领域亟待解决科学问题。本项目以 CCS 过程中含杂质的超临界 CO2 输送管线为研究对象，通过相行为和水化学特性分析，建立超临界 CO2-H2O-杂质体系流体热力学模型，阐述杂质与水相析出及水化学特性的关系。通过腐蚀模拟实验、高压原位电化学测试和腐蚀膜的微观表征，揭示超临界 CO2 输送管线钢腐蚀膜生长演化机制及腐蚀电化学机理，同时澄清杂质组分之间对管线钢腐蚀的协同作用机理，从本质上阐明含杂质超临界 CO2 输送管线的腐蚀机制。获得的主要研究结果如下：.建立了CO2-H2O-杂质互溶度热力学模型，从热力学上证明了在超临界CO2流体中杂质可以促进水相析出。确定了杂质浓度对水相析出的影响程度，明确了主要杂质及杂质之间交互作用对析出水相化学性质的影响。提出用腐蚀影响因子(Ci)和协同作用影响因子(Sm)表征杂质及杂质间协同作用对X65管线钢腐蚀的影响程度。揭示了杂质间协同效应的本质：通过产生新的腐蚀性物质加速管线钢的腐蚀。确定了杂质之间交互作用对腐蚀膜特性及演化的影响，探明了管线钢局部腐蚀演化过程。探明了随着含水量变化杂质对X65钢腐蚀的影响机理，拓展了DYNAMIS CO2质量标准建议的H2O和SO2的许用浓度。超临界CO2输送管线腐蚀的特殊规律和机理丰富了现有的腐蚀理论体系，为建立CCS中超临界输送流体的质量标准提供实验和理论基础，并为超临界CO2输送管线的腐蚀预测和完整性管理提供科学依据和技术支撑。