硫磺回收装置腐蚀机理与防护分析

Corrosion Mechanism and Protection of Sulfur Recovery Unit

目的对硫磺回收装置的腐蚀机理进行细化研究。方法研究NH4HS垢下腐蚀、CO2-H2O腐蚀、H2S-H2O腐蚀、H2SO4/H2SO3腐蚀、硫高温腐蚀等几种腐蚀情形,为预防设备管线腐蚀提供相应的理论依据,并且通过硫磺回收装置的液硫及管线腐蚀、高温掺和阀腐蚀、阀门腐蚀及点火枪部位腐蚀等典型案例进行详尽分析。结果通过能谱(EDS)对现场损坏管线分析得知,在液硫界面产生的氧、碳、硫等腐蚀产物导致液硫池蒸汽管线和伴热管腐蚀断裂、液硫泵壳腐蚀。该部分腐蚀产物与液硫池中的水发生反应,生成多种酸(硫酸、亚硫酸等)造成腐蚀。随着液位逐渐升高,腐蚀范围不断上升和扩大。结论由于高温掺和阀阀芯基本处于800~1000℃的高温环境中,大量的单质硫、二氧化硫、硫化氢及有机硫物质在高温环境中,形成高速气流,设备经过高速气流的冲刷,造成严重的腐蚀。同时NH4HS结晶在阀门或点火枪部位析出,在流速较低的部位发生沉积,导致设备功能下降和电化学垢下腐蚀。通过分析硫磺回收装置的工艺原理、腐蚀机理及腐蚀现状,结合具体案例分析,提出相对应的防护措施。

The work aims to study the corrosion mechanism of the sulfur recovery device in detail.Several corrosion types such as NH4HS scale corrosion,CO2-H2O corrosion,H2S-H2O corrosion,H2SO4/H2SO3 corrosion and high temperature sulfur corrosion were studied to provide corresponding theoretical basis for preventing equipment pipeline corrosion.Typical cases such as liquid sulfur and pipeline corrosion,high temperature blending valve corrosion,valve corrosion and ignition gun corrosion were analyzed in detail.The energy spectrum(EDS)analysis of the on-site damaged pipeline showed that the main corrosion products such as oxides,carbon compounds and sulfur compounds of the liquid sulfur interface caused breakage of the low-pressure steam pipe of the liquid sulfur pool,corrosion breakage of the heat tracing pipe and corrosion of the pump casing.The corrosion product reacted with water in the liquid sulfur pool,generating a variety of acids(sulfuric acid,sulfurous acid,etc.)and causing corrosion.As the liquid level gradually rose,the corrosion range continued to rise and expand.Due to the high temperature blending valve core is basically in a high temperature environment of 800~1000℃,a large amount of elemental sulfur,sulfur dioxide,hydrogen sulfide and the organic sulfur substance form a high-speed airflow in the high-temperature environment,and the equipment is washed by the high-speed airflow,causing serious corrosion to the equipment.At the same time,NH4HS crystallizes in the valve or ignition gun,and it is likely to deposit on the parts with lower flow rate,which will not only reduce the equipment function,but also cause corrosion under electrochemical scale.By analyzing the process principle,corrosion mechanism and corrosion status of the sulfur recovery device,combined with specific case analysis,corresponding protective measures are proposed.