含硫气体处理中硫化铁的利与弊

Analysis on Advantages and Disadvantages of Iron Sulfides in Sour Gas Treatment

为了减少含硫气体处理中硫化铁对装置的腐蚀,有必要弄清腐蚀机理,识别影响腐蚀严重性的条件。在处理含硫天然气的装置中,一定会有硫化铁存在。硫化铁是在无氧条件下铁(Fe)与硫(S)反应生成的。在胺系统中,这样的反应在铁(Fe)与硫化氢(H2S)之间进行。这种反应起初只是金属腐蚀,但在理想条件下,生成的硫化铁会"粘"在管壁和容器内部构件上,起保护膜的作用,具有防止管道或容器进一步腐蚀的优点。但硫化铁膜一旦破损,就可能形成电偶型腐蚀电池。硫化铁膜越弱,越容易被除去或分层,致使二氧化碳进入沉积物下,形成攻击性腐蚀。一般说来,化学清洗是清除系统中硫化铁的最有效方法。所以,清除胺系统中破损的硫化铁十分重要。

In order to reduce corrosion of iron sulfides on amine plant in sour gas treatment,it is necessary to make clear relative corrosion mechanism and recognize the conditions that affect corrosion severity.Amine plants treating gas containing H2S will have iron sulfides in the system.FeS is the reaction product of iron(Fe) and sulfur(S) in the absence of oxygen.More especially to amine systems,this reaction is between iron and H2S.This initial reaction is a form of metal corrosion;however,under ideal conditions the FeS formed then 'sticks' to the walls of piping and vessel internals and acts as a protective film thus retarding further metal corrosion.Once the FeS scale is compromised,the chance of developing a galvanic-type corrosion cell is increased.Weaker scales are also easily removed or subject to delamination,allowing for the potential ingress of CO2 under the deposit and the subsequent aggressive under-deposit corrosion.Chemical cleaning,in general,is the most effective method of FeS removal.So,removal of those compromised iron sulfides out from the amine system is very important.