CO2 and stainless steel compatibility

[ports394]

We'e looking at some drying equipment that will have its 'wetted' parts made of 304 or 316 stainless steel.

I was told by someone that CO2 is not a good drying gas to run with spray dryers because at the higher temps (150C+) it can cause corrosion and damage the stainless. And so they recommend using Nitrogen as the gas.

Has anyone else seen this or know about this?

 

[EdStainless]

What pressure?
The CO2 will dissolve in the water and dissociate into carbonic acid, a weak acid. At high pressure and temp you can get the pH down to 3 or so. At ambient conditions it will only go down to about 5.5

Look at using a lean duplex stainless (2101, 2102, 2202). They will be twice as strong as 316, about the same price, and the welds will have better corrosion resistance.

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Plymouth Tube

 

[ports394]

EdStainless,

Thank you. I was hoping someone would bring up carbonic acid. Since we're removing ethanol and water from the feed stream.. CO2 and water can-will form it. But that should fall apart in the condenser because of the low temperatures and be removed from the CO2 stream.

I'll look into the duplex stainless. Looks like an interesting idea.

Overall, I think we're looking at using Nitrogen as our carrier gas... but we may have an option to get very cheap, bulk, CO2... we would just need to clean it up and dry it.

 

[emxhps06]

What are the 'wetted' parts, if I may ask? If the equipment should lose some of the 'wetted' parts, would it cause a major outage or business consequence?

 

[ports394]

emxjps06,

Good question. I've worked in test labs and production labs, and what I've been taught is.. a wetted part is anything that contacts your product/process.

So for a heating jacket, I may not care that the jacket is made of carbon steel... but I care that the inside area of the tank that my product is touching, is 316L.

 

[emxhps06]

Life cycle cost is ultimately the contributory factory that ties in with the inspection/maintenance periodicity. How long did the previous sprayer dryer last before a replacement is needed?


I don't know this would help much but it talks about carbon capture plants and carbon dioxide corrosion issue.