双相不锈钢在管流系统中的流动腐蚀动力学模型

针对管流体系 ,根据动量、能量和质量守恒原理 ,应用壁函数、k -ε湍流运动模型确立了管流体系中的计算流体力学模型和质量传递模型 ;结合腐蚀实验确定双相不锈钢流动腐蚀过程中的主要控制因素及其影响程度 ,分析了动力学过程 ,建立了双相不锈钢在 3.5 %NaCl溶液中的流动腐蚀动力学模型 .同时 ,采用数值计算方法计算了流动腐蚀速度 ,并与实验结果进行了验证 .揭示出双相不锈钢的流动腐蚀受阳极钝化过程控制 ,离子在电极表面钝化膜中的迁移、扩散过程为速度控制步骤 .腐蚀电化学因素在双相不锈钢流动腐蚀过程中起着主导作用

FLOW-INDUCED CORROSION KINETICS MODEL OF DUPLEX STAINLESS STEEL IN FLOW LOOP SYSTEM

Wall function, k-ε turbulence model are used in the present study.The numerical hydrodynamics models and mass transfer models in flow loop system are defin ed in accordance with the basic theory of hydrodynamics and conservation of mass ,momentum and energy.Flow-induced corrosion kinetics model of duplex stainless steel in flowing 3.5% NaCl solution is set up on the basis of determining main controlling factors and their degree of influence in flow-induced corrosion by some electrochemical experiments,and of analyzing the kinetics process of f low-induced corrosion of duplex stainless steel. The numerical method used in this study is based on the control volume approach for discretization of partial differential equations that express the characteri stics of fluid flow and mass transfer.The user program is compiled.In accordance with flow-induced corrosion kinetics models,flow-induced corrosion rates are numerically calculated with SIMPLE algorithm.The flow-induced corrosion rates calculated by numerical method are compared with the ones measured by mass loss.The numerically computed flow-induced corrosion rates are mostly equal to the ones measured by mass loss experiments.It proves that the flow-induced corrosion kine tics models are correct and accurate,and that the user program is reasonable.Th e models are founded on the basis of some electrochemical experim ents and reasonable hypothesis. Flow-induced corrosion of duplex stainless steel in flowing 3.5% NaCl solution is controlled by anodic pass ivation process and the diffusion or transfer process of ions in passivation fil m is a speed-controlling step.Corrosion electrochemical factor plays a dominant role in flow-induced corrosion of duplex stainless steel.