[Terrapreta] Let's talk retort materials for a little bit

[Kevin Chisholm]

Dear Greg

Greg and April wrote:
> What kind of materials make a good retort?
>  
> Titanium?
> Carbon Steel?
> Stainless Steel?
>  
> What?

There are several answers...

1: If you want low cost... then carbon steel
2: If you want longer life, then use thicker carbon steel
3: If you want longer life still:
    lower the temperature of the metal to hold it to about 700 F
4: If you want longer life still, use SS, and limit shell temperature to 
aprox. 900 F

Enclose the heated surfaces so that they only "see" products of 
combustion, with minimum possible excess air.

Titanium is very expensive, but would probably be good to a higher 
temperature. However, it has a significant tenancy to form Nitrides and 
Carbides.

Hope this is helpful.

Best wishes,

Kevin
>  
> Greg H.
>  
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