硫磺回收装置腐蚀若干问题探析

Discussion on several issues of corrosion of sulfur recovery unit

硫化氢(H 2S)具有高度危害和爆炸危险双重特性。H 2S浓度是管线腐蚀问题的主要影响因素之一,涉及高浓度湿H 2S的管道及设备的设计、制造应选择抗硫化物应力开裂和(或)抗应力腐蚀开裂的碳钢、低合金钢和耐蚀合金。胺液系统出现泡沫、颜色变深(黑)、过滤速度减缓以及硫化亚铁(FeS)或固体悬浮物等现象时,要及时分析形成热稳定盐的原因并采取措施。一般控制胺液系统的热稳定盐质量分数不大于1.0%,固体悬浮物质量浓度不大于50 mg/L,氯离子质量浓度不大于500 mg/L。硫磺回收装置原料酸性气的H 2S体积分数为40%~90%,对高浓度酸性气湿H 2S环境、液体硫磺环境和胺液系统,在停工和检(维)修过程中应避免出现过氧导致FeS自燃的现象,特别要注意硫磺会增大FeS自燃的危险性。

H 2S is a lethal highly hazardous poison with double characteristics of high hazard and explosion risk.H 2S concentration is one of the main influencing factors of pipeline corrosion problems.The design,manufacture and construction of pipelines and equipment involving high concentration of wet H 2S should choose carbon steel,low alloy steel and corrosion resistant alloy,which can resist SSC and/or SCC.If foam,darker(black),slower filtration speed and FeS or suspended solid appear in the amine liquid system,the reasons for the formation of thermally stable salts should be analyzed in time and measures should be taken.Generally,the thermally stable salt concentration of the amine liquid system should be less than or equal to 1.0%,the concentration of suspended solid should be less than or equal to 50 mg/L,and the concentration of chloride ion should be less than or equal to 500 mg/L.The H 2S concentration in the sour gas of the sulfur recovery unit is from 40%to 90%.For high-concentration sour gas wet H 2S environment,liquid sulfur environment and amine liquid system,care should be taken to avoid excess oxygen causing FeS spontaneous combustion during the shutdown and overhaul(maintenance)process.Special attention should be paid to the role of sulfur in increasing the risk of FeS spontaneous combustion.