What material is suitable for upgrading the bottom reboiler of the wastewater stripping tower?
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The tube bundle of the reboiler at the bottom of the wastewater stripping tower is suffering from severe corrosion. Steam flows inside the tubes, while sulfur-containing wastewater flows outside them; the temperature is around 150 degrees. Carbon steel was used in the past and suffered severe corrosion within half a year, while grade 09 steel was used later, but it also experienced severe corrosion after about one and a half years. Do any experts have any suitable materials to recommend?
After researching a lot, it was found that only surface-aluminized materials are used; using stainless steel would lead to chloride stress corrosion cracking
This post was last edited by ylb913 on 2018-7-24 07:07. We have been using stainless steel for over twenty years; in the meantime we also tried aluminum infiltration and nickel-phosphorus plating, but none of those methods worked. When it came to stainless steel, at that time we only knew about 0Cr18Ni9Ti or 1Cr18Ni9Ti.
Is it better if stainless steel contains molybdenum?
Is it better if stainless steel contains molybdenum?
Corrosion still occurs, but the reason for it might be that the heat exchanger was not cleaned for a long time after the unit stopped operating; residue such as coke powder accumulated inside the shell side, resulting in under-scale corrosion (at room temperature). If the unit keeps running, there is no problem. We have a set of sewage stripping units, with two sewage towers serving as backups for each other.
Is the chloride content high in the wastewater?
Since corrosion can also occur with stainless steel, some companies consider the cost factor and opt for carbon steel instead; it can last for a year or longer, and it needs to be replaced only when there is leakage. Additionally, the reboiler is of the kettle type. For this as well, the material should be chosen based on cost-effectiveness, taking into account the conditions of one’s own equipment.