摘要
目的分析烷基化废酸处理系统中风机叶轮的失效特征和失效位置分布并研究其失效机理。方法采用理化检验分别对失效叶轮和腐蚀物进行微观形貌检测、元素分析、化学结构和物相分析,最后选用VOF模型且以过程气为主相、硫酸为次相,利用Fluent软件进行计算,流体动力学(CFD)仿真分析风机叶轮内部流场对叶轮失效的影响。结果风机叶轮化学成分符合相关标准,金相组织无异常,叶轮的后轮盘及叶片的腐蚀比前轮盘腐蚀严重并有显著减薄现象,叶轮基体在硫酸的化学腐蚀作用下,主要腐蚀物为多种Fe、Cr和Ni的硫酸盐,包括FeSO_(4)·H_(2)O、NiSO_(4)·H_(2)O和Cr_(2)(SO_(4))_(3)等,CFD仿真结果表明,流体在叶轮中速度和压力的不均匀分布导致流体的不稳定流动和腐蚀介质积聚,从而加剧叶轮腐蚀;腐蚀介质硫酸主要集中在后轮盘、叶片压力面外缘及吸力面靠近后轮盘的区域,硫酸体积分数最大值为3.22%。由于流体速度变化和腐蚀介质的不稳定流动,靠近叶轮中心的叶片吸力面和后轮盘中心位置的剪切应力较大。结论过程气在化工风机叶轮高速旋转时形成了产品酸,且破坏了叶轮基体表面钝化膜,在流体腐蚀与冲刷的交互作用下,叶轮减薄直至穿孔失效。研究为分析风机叶轮的失效行为和提高其服役寿命提供了依据。
This study aims to analyze the failure characteristics,the distribution of failure locations and the failure mechanism for the blower impeller used for the alkylation waste acid treatment system.The study integrates experimental analysis and computational simulations to identify specific factors contributing to impeller deterioration,providing a comprehensive approach to understanding the complex interactions between impeller components and corrosive environments.Based on a series of physical and chemical testing,microscopic morphology,elemental analysis,chemical structure and phase analysis of the failed impeller and corrosion products are studied.With process gas as the primary phase and sulfuric acid as the secondary phase in the VOF(Volume of Fluid)model,Computational Fluid Dynamics(CFD)simulations are applied to analyze the internal flow fields of the impeller and their effect on failure.The results show that the chemical composition of the blower impeller meets the relevant standards,and the metallographic structure shows no abnormalities.The rear disk and blades of the impeller suffer from significantly more severe corrosion than that the front disk suffers.Specifically,the impeller surface exhibits extensive deposition of dark green corrosion products and significant thinning resulting from corrosion.Scanning Electron Microscopy(SEM)analysis reveals a distinct wavy striation pattern,along with numerous pits of varying sizes aligned with the direction of fluid flow.Additionally,the surface displays a network of extensive cracks,numerous voids,and substantial accumulation of corrosion residues.Energy dispersive spectroscopy(EDS)results show that the corrosion products are mainly Fe,S,Cr and O.Fourier-transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)analysis further confirm that the chemical corrosion of the impeller substrate is primarily caused by sulfuric acid,resulting in the formation of various sulfate compounds of Fe,Cr,and Ni,including FeSO_(4)·H_(2)O,NiSO_(4)·H_(2)O,Cr_(2)(SO_(4))_(3),etc.,as the predominant corrosion products.The CFD simulations reveal that the uneven distribution of velocity and pressure results in fluid unsteady flow and corrosive medium accumulation,and eventually increases corrosion of the impeller.Sulfuric acid as the corrosive medium is mainly concentrated on the areas of the rear disk,the outer edge of the blade's pressure surface and the blade's suction surface close to the rear disk.And the maximum volumetric concentration is 3.22%.This corresponds with the areas where the impeller exhibits significant corrosion thinning and ultimately suffers perforation failure.Due to variations in fluid velocity and the unstable flow of the corrosive medium,the shear stress on the blade's suction surface and at the center of the rear blade is elevated,reaching a maximum of 79.6 Pa.As a result,significant corrosion is observed with increased depth on the blades near the center of the impeller,and severe corrosion is evident at the central region of the rear disk.These findings are consistent with the actual corrosion conditions observed on the impeller.With the high speed of the chemical industry blower impeller for the process gas,the product acid is formed and the passive film of the impeller substrate is destroyed.The coupling of fluid corrosion and erosion leads to impeller thinning until perforation failure.This study can offer valuable insights into the impeller failure behavior and provides recommendations for extending its service life,including strategies for design and material enhancements to mitigate corrosion and erosion.
作者
孙建芳
陈勇
李吉
杨鹏飞
周胜军
蔡嘉吉
苏峰华
SUN Jianfang;CHEN Yong;LI Ji;YANG Pengfei;ZHOU Shengjun;CAI Jiaji;SU Fenghua(School of Mechanical and Automotive Engineering,South China University of Technology,Guangzhou 510641,China;Fujian Refining&Petrochemical Company Limited,Fujian Quanzhou 362800,China)
出处
《表面技术》
北大核心
2025年第12期114-123,共10页
Surface Technology
基金
广东省基础与应用基础研究基金项目(2023A1515240006,2024A1515010452)
粤港澳大湾区(佛山)先进制造业国家卓越工程师创新研究院联合培养扶持项目(2023FCXM002)。
关键词
化工风机叶轮
理化检验
CFD仿真
腐蚀
chemical industry blower impeller
physical and chemical testing
CFD simulation
corrosion
