Selection of multi-strand water treatment corrosion-resistant materials
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I. Components of copper-containing wastewater (water volume to be treated: 300 t/d)Parameter | Value
Acidity (as HCl) | 17%
CODCr | 20,000–25,000 mg/L
BOD5 | Approximately 1,000 mg/L
NH3-N | Approximately 30 mg/L
Cu2+ | 0.08 mol/L
Salinity | ~18%
Toluene | 570 mg/L
Sulfonyl chloride | ~
Methyl ortho-chlorobenzoate | ~
Ortho-chlorobenzoic acid | ~
Ortho-aminomethyl compound | ~
Components of ammonia-containing wastewater (water volume to be treated: 600 t/d)
Parameter | Value
pH | ~4
CODCr | ~15,000 mg/L
BOD5 | Approximately 4,000 mg/L
NH3-N | Approximately 50 mg/L
Cu2+ | Approximately 150 mg/L
Salinity | ~10%
Toluene | Small amount
Methanol | ~0.1%
Ortho-chloro** | ~0.15%
Ortho-aminomethyl** ester | ~
Carboxylic acids | ~
Aromatic nitrocompounds | ~
III. Acid-extracted insoluble saccharin washing water
(Accumulated water from acid extraction of insoluble saccharin; water volume to be treated: 150 t/d)
Parameter | Value
pH | ~1
CODCr | ~20,000–40,000 mg/L
BOD5 | Approximately 3,000 mg/L
NH3-N | Approximately 80,000 mg/L
Salinity | Ammonium chloride content: approximately 17%
Insoluble saccharin | Small amount
Amidated oil | Small amount
I have a project involving these three types of wastewater, and the client requires treatment using evaporation crystallization equipment. Could you please advise me on whether 316L steel or duplex steel would be more suitable for this purpose? Is corrosion more severe in factory MVR equipment when it operates at 90 degrees? Thank you!
How high is the temperature? Metal materials are not suitable
Apply high-temperature anti-corrosion treatment to the equipment
The third stream of ammonium chloride solution is at around 90 degrees, while the first and second streams are generally treated at room temperature
Silicon carbide heat exchangers should be suitable for use in what you mentioned; we also manufacture MVR units, as well as silicon carbide heat exchangers that have been developed recently!
I just want to ask whether 316L or duplex steel can be used to handle these three types of water; if other materials work as well, please let me know
The effects of using these two may not be ideal
What constitutes the ideal material?
I checked the CHEMICAL RESISTANCE GUIDE FOR METALS AND ALLOYS; the Hastelloy B series can basically meet your requirements. However, in the presence of salt and acid at 90°C and a concentration of 20%, there is an annual corrosion rate of 0.02 inches for Hastelloy B, which is approximately 0.5 mm. Tantalum heat exchangers – you might want to take a look at those as well. After checking, they meet all your requirements perfectly. The initial cost is a bit high, but the maintenance costs are generally low in the later stages; overall, the cost is lower than that of graphite and silicon carbide heat exchangers. :lol