Determining the corrosivity of HF gas
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The aluminum electrolysis industry generates large amounts of low-temperature flue gas that can be used for waste heat recovery. The issue at hand is that the flue gas contains a small amount of HF (within 10 mg/m3) as well as trace amounts of SO2. Can heat exchangers made of stainless steel or carbon steel be used for dealing with this small amount of HF?
The flue gas waste heat recovery process involves high temperatures and the presence of corrosive gases; under such harsh operating conditions, graphite heat exchangers are recommended. --
Graphite heat exchangers aren’t resistant to wear, right? There is a lot of dust in the flue gas from electrolytic aluminum production; I forgot to mention that.
A small amount of low-temperature HF and SO2 gases can be handled using Menol K500 material; for carbon steel, several more units are needed in order to allow for replacement!
High-nickel materials work well, but they are a bit expensive. Does low-concentration HF gas cause severe corrosion of carbon steel and stainless steel?
In other words, are there any data related to the corrosion rate?
In other words, are there any data related to the corrosion rate?
A small amount of dust is not a problem, as the flue gas pressure is low and the gas flow velocity is not high; the accumulated flue gas dust can be washed regularly to prevent blockages.
There is a unit that uses 17-4PH, and the results are said to be very good; you can check that out. MONEL K500 is the only material other than MONEL400 that can be used in HF.
Oh? Thank you, I’ll inquire about this material.
This post was last edited by Myth/ty Taotao on 2017-11-27 at 14:29. Carbon steel is sufficient; using other materials is a waste. Graphite is not recommended. I have been working with the AHF process for 6 years – believe me, HF is the best option. C alloy is too expensive; carbon steel is the next best choice, while stainless steel should be avoided