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

[MFH]

If by "retort" you mean the drum used to contain the material to be
pyrolised, then the decision about material is between cost and longevity.

 

Normal steel will last for years and won't heat-distort if the retort is
heated and cooled reasonably evenly.

 

A retort made from "boiler plate" will last longer and be more resistant to
distortion.

 

Cast iron is better still. I've been hunting for scrap cast iron pipes.

 

My experience in this area is from using various materials in various shapes
as fireboxes under drying beds for produce like cocoa beans or copra. We
once fluked some cast iron pipes left behind by the Japs from WWII, which
proved to have very long lives when used as fireboxes. Also had some made
using normal steel plate and also boiler plate, with the latter having a
longer life.

 

Shape was important. Flat surfaces as in a box-shaped firebox distorted in a
matter of weeks. Cylindrical shapes were best, particularly if the sides
were supported by concrete walls thus preventing a gradual change from
cylindrical to oval. Best of all was to line the inside of the cylinder with
2" of cast refractory cement, giving a life despite 24/365 use of many
years. This is not suitable for char production as the cement has a
considerable insulating effect.

 

316 or other stainless steels may be okay but at a serious cost escalation.
I'd suggest that its more cost-effective to use the cheapest steel and toss
it out in a couple of years.

 

Max H

 

 

 

 

  _____  

From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Greg and April
Sent: Thursday, 15 May 2008 5:18 AM
To: Terra Preta
Subject: [Terrapreta] Let's talk retort materials for a little bit

 

What kind of materials make a good retort?

 

Titanium?

Carbon Steel?

Stainless Steel?

 

What?

 

Greg H.

 

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