32.5% urea Diesel Exhaust Fluid - heat exchanger tube material?

[dru8923]

I'm looking for the best material with high corrosion resistance to 32.5% urea, that also has high thermal conductivity to be used in a heat exchanger. The urea will be in the tube side, pumped in at 60F and heated to 350F. Therefore, the tubes will initially contain urea liquid then after boiling point - ammonia gas, co2 and h2o vapor.

From my research:

Copper alloy - high thermal conductivity, poor ammonia corrosion resistance.
Aluminum - high thermal conductivity, unclear about ammonia corrosion resistance.
Stainless - high corrosion resistance, poor thermal conductivity.

 

[mrfailure]

Copper-free aluminums resist gaseous and anhydrous ammonia though pitting can result if the solution contains "contaminants". Al is resistant to CO₂. Type 3003 Al is resistant to urea solid and solution (reference: Handbook of Corrosion Data, 2nd Edition, ASM International).

Aaron Tanzer

http://www.lehightesting.com

 

[dru8923]

Thank you.

Any idea why ISO specifies no aluminum for 32.5% urea (AdBlue brand)

 

[EdStainless]

Your perception of SS having poor heat transfer is out of line.
If you have 1/3 the wall thickness that you would need in Al or Cu then the difference is negligible.
The largest resistance to heat transfer is the surface film anyway, the tube walls in any metal will only be a few % of the total resistance.

Worth reading:
Material Corrosion Investigations for Urea SCR Diesel Exhaust Systems
Date Published: 2009-10-06
Paper Number: 2009-01-2883

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[dru8923]

Thank you

 

[MJCronin]

Consider the Sandvik 3R60 (Urea grade)stainless steel.

It is a variant of 316 developed for urea service.

See: ASTM 316L; UNS S31603; EN 1.4435

http://www.matweb.com/search/datasheet.aspx?matguid=4c3357cbe6a64de2ab1948878c8c86c1&ckck=1

also see:

http://www.matweb.com/search/datasheet.aspx?MatGUID=69fd020c300843eaa62e37d1d45b8909

 

[EdStainless]

At the concentrations and temperatures that you are dealing with standard 316L would be plenty good.
This is DEF right?
So it will be clean with minimal contaminates.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[dru8923]

Thank you.

We only have air for the reactor do you know of any heater/blower combos that will supply 350-400F air at 500-800scfm?