Why is the corrosion caused by hydrogen sulfide and ammonia together so severe?
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The ammonia level is 300 g/L and that of hydrogen sulfide is 230 g/L; the corrosive effect is quite strong. After operating for about six months,
It will definitely corrode, and it will corrode quickly
In my opinion, hydrogen sulfide reacts with iron to form ferrous sulfide, while ammonia dissolves in water to create an alkaline environment. Ferrous sulfide then reacts with this alkaline solution formed by ammonia, which accelerates corrosion; ammonia acts as a catalyst in this process! If it’s just corrosion, the material can be replaced! !
What is your material? It seems the material needs to be replaced; the heat exchangers are completely clogged. There is no heat exchange effect left. Depending on the material, ordinary carbon steel, copper, and similar materials corrode very quickly. Try a 310S instead, or one made of graphite, lined with fluoropolymer, or coated.
It is recommended to use graphite heat exchangers to ensure hassle-free operation. --
No obvious corrosion was observed; scaling was prominent, consisting of ammonium salts formed by hydrogen sulfide and ammonia. Removing the scaled layer did not necessarily reveal any obvious corrosion
Well, the corrosion caused by hydrogen sulfide isn’t that severe; the water is alkaline, as you said. The pump has been replaced with a 304 stainless steel one that is resistant to corrosion in Dalian, but the mechanical seal doesn’t work well – a Hastelloy seal would be needed, yet its cost is too high. We still can’t make a decision at the moment. For heat exchangers, 304L is the best choice; currently, 304 is being purchased
Carbon steel, ordinary, third time.
Use graphite heat exchangers to ensure a service life of over ten years. --
Graphite would be good, and it’s also relatively cheap.