Material selection for anti-corrosion evaporation tanks
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The mother liquor produced during our company’s manufacturing process contains about 50% ethanol, which needs to be evaporated and recovered using an evaporation tank. The pH of the mother liquor is around 4.5–5.5, the chloride ion concentration is approximately 4000 PPm, and the temperature is around 100°C; steam is used for heating. The entire body of the current kettle is made of 316 stainless steel, and the steam coil (which is in direct contact with the mother liquor) is also made of 316 stainless steel. Corrosion is severe, and the material becomes brittle as a result of corrosion, making it impossible to repair. Is there any material that is more corrosion-resistant and offers better cost-performance for this application? Thank you so much.
Chloride ions cause corrosion of stainless steel. Titanium and titanium-molybdenum-nickel alloys are used.
For such operating conditions, titanium alloy of TA10 material can be considered.
Under process conditions with high chloride ion content, it is recommended to use a graphite evaporative recovery unit.
Enameled steel equipment, titanium materials, zirconium materials. Evaporation stirring is recommended; the evaporation rate is 1.5 to 2 times that of frame or anchor types
Change the heating method to use steam or a jacket
If chloride ions are too high, intergranular corrosion occurs; use a lining in the absence of pressure, and titanium material in the presence of pressure.
For equipment that uses steam for heating, I consulted manufacturers specializing in linings and coatings, and they all said they couldn’t do it; titanium is quite expensive. I’m not sure whether duplex steel 2205 could work
The results are rather special: glass lining is not suitable, nor is evaporation stirring. I’m not sure whether duplex steel 2205 will work for these operating conditions
If you have no experience in using containers made of duplex steel, you can consult the equipment manufacturer.