油水分层流条件下腐蚀动力学特性模拟  

Simulation of corrosion kinetics in stratified oil-water flows

作　　者：王凯[1] 黄慧 南翠红 王跃社[2] 卢金玲[1] WANG Kai;HUANG Hui;NAN Cuihong;WANG Yueshe;LU Jinling(State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China,Xi'an University of Technology,Xi'an 710048,Shaanxi,China;State Key Laboratory of Multiphase Flow in Power Engineering,Xi'an Jiaotong University,Xi'an 710049,Shaanxi,China)

机构地区：[1]西安理工大学西北旱区生态水利国家重点实验室,陕西西安710048 [2]西安交通大学动力工程多相流国家重点实验室,陕西西安710049

出　　处：《化工进展》2021年第S02期40-47,共8页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(51906200,51839010,51879216);陕西省教育厅重点实验室科研计划(19JS045)。

摘　　要：当石油输送管道内处于油水分层流条件时,管道底部与酸性水层接触极易造成内腐蚀,严重威胁管道安全,传统的静止和单相流条件的腐蚀预测方法已不能指导管道的安全运行,而多相流动、离子传质、化学反应及电极动力学等多种不同尺度的物理化学过程对多相流腐蚀预测提出了挑战。本文基于多相流动特性及电化学腐蚀特性的耦合机理提出了分层流条件下腐蚀动力学模型,首先建立油水三层流传质计算模型,进而基于溶液区域和产物膜内部的传质计算,依据阴阳极电化学反应电流密度与传质通量之间的平衡关系,形成多相流条件下腐蚀预测方法。探究了离子传质、电极反应以及产物膜动态生长的耦合过程对腐蚀行为的作用机理,揭示了CO_(2)分压、温度对腐蚀发展规律的影响机制。研究发现温度、CO_(2)分压的改变会导致平衡反应方向的移动,从而改变离子浓度;离子的扩散系数是决定传质系数变化的内在原因;腐蚀速率的变化规律由产物膜生长和电极反应两种因素共同决定:腐蚀产物膜的生长会阻碍反应离子的传质效应,从而抑制腐蚀;而离子浓度的升高或传质增强会加快电极反应,促进腐蚀。The stratified oil-water flow regime is always encountered in long-distance crude oil transmitting pipelines,and then the acid-containing water layer probably lead to the serious internal corrosion of the bottom of the pipe,which becomes a significant threat to the long-term safe running.The multiphase flow,mass transfer,chemical reaction and electrode kinetics pose a challenge to corrosion prediction.A novel flow-induced corrosion kinetics model was proposed on the basic theory of multiphase flow dynamics and corrosion kinetics.Firstly,a mass transfer model under the oil-water three-layer flows was established.Secondly,based on the mass-transfer calculation of the ions across the bulk solution and the corrosion film,a prediction method for the multiphase flow corrosion was established according to the current density equilibrium of the anodic and cathodic electrochemical reactions.The interrelationship between the corrosion process and the ion mass transfer,electrode reactions and the dynamic growth of the corrosion film was revealed.Furthermore,the effects of CO_(2) partial pressure and temperature on the corrosion evolution were investigated.The results indicate that the CO_(2) partial pressure and temperature could change the ion concentration by altering the moving direction of the equilibrium reactions.The diffusion coefficient was the intrinsic factor to determine the mass transfer process.Moreover,the corrosion evolution process was determined by two factors:the dynamic growth of corrosion film and the electrode reactions.The continuous growth of corrosion film could impede the mass transfer of the ions involved in the reactions,thereby hindering the corrosion process,while the increment of ion concentration and mass transfer could speed the electrode reactions and then promote the corrosion process.

关 键 词：石油 多相流 腐蚀 电化学 动力学模型 

分 类 号：TK17[动力工程及工程热物理—热能工程]