poultry litter mat'l handling- SS grade =? 1

[davefitz]

OK. We will have to generate 12.5% of our electric power in North Carolina by renewable energy, by 2020. In NC , that means biomass ( wood, poultry litter)co-fired in boilers or gasifiers.

I heard the UK feather burners needed to upgrade to SS to combat excessive corrosion in the mat'l handling equipment. No clue as to how far they had to go 304==>316==>317==>2205==>al6xn==hastelloy ??

Any experience out there?

 

[EdStainless]

It depends on which part of the system you are talking about.
On the front end I would suppose that something like 2205 would be suitable.
I won't even touch the subject of coatings for the boiler tubes.
For waste gas handling you will need to think about what special requirements there are. I would relate this to trash burners and look at it being slightly worse than a coal fired environment. This usually would be starting with AL-6XN and working up from there.

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Plymouth Tube

 

[PeterCharles]

If you are talking about the bulk materials handling of the biomass PRIOR to combustion, then it's down to what actual material you're actually handling.

Dry wood chips are no problem.
Wet wood chips are a bit corrosive. In general mild steel is OK as long as some corrosion is acceptable. However wood chips are frequently handled in chain conveyors and corrosive attack to the joints of the chain is well known. For hoppers and conveyor casings you could use 1.4003 (3CR12 as was).
Poultry litter is more corrosive than wet wood chips but I haven't heard the need for anything more than 304.

 

[davefitz]

Thanks for this information.

I am mostly concerned with the front end handling- poultry litter. In the US , it is common practice for the farmers to add a lot of alum (aluminum sulfate) to the litter, to suppress ammonia formation during the weeks the litter sits below the henhouse. So, the litter has chlorine, sulphur , urea, moisture, etc.

PeterCharles: are you certain 314 is the likely required limit?

 

[PeterCharles]

Am I certain -- NO
Some years ago I was involved in selecting some materials for use in corrosive conditions. I took the easy option and tested different materials.
Application 1
Mild steel (control), MS Sherardized, 3CR12(1.4003), 304, 316
MS and Sherardized - equally useless
3CR12, 304, 316 - all equal with no corrosion
So we used 3CR12!
Application 2
3CR12, 304, 316
3CR12 - pitted and stained
304, 316 - equal with no corrosion
Used 304!

Suggest you get some different materials and bury them in poultry litter and see what happens.

 

[EdStainless]

I would stick with 3Cr12 or go to a duplex (LDX2101 or similar) I don't see 304 or 316 being a good solution for this with the risk of stress corrosion cracking.

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Plymouth Tube

 

[PeterCharles]

But how serious a risk is stress corrosion cracking?
As yet we have no idea what "front end handling- poultry litter" actually is.
Then there is the question of price and availability of "LDX2101" in the correct form.
Had plenty of recommendations for materials in the past only to find you can't get it in the form you need!

 

[EdStainless]

I have seen 304 crack in exposure to full sunshine. Exposure to acidic chloride media will make this a higher risk.
I know that a lot of 304 and 316 are used in salt exposure with no cracking, but if these parts are going to see mechanical loading I wouldn't risk it.

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Plymouth Tube

 

[davefitz]

It is my understanding that one can avoid SCC in 304 if you can maintain the (unsensitized) metal temp below 140 F .OR. maintain max stress at raisers to below 10 ksi. If there are welded parts or risk of operation over 140 F then we would investigate duplex.

One would think that MIC would be an issue in this application.

Anyhow, for purposes of an initial cost estimate, I will spec 304 SS.

Thanks for the help