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

[Greg and April]

As this is going to be the experimental model, I'm not currently worried about drying out the next batch.

Greg H.


----- Original Message ----- 
From: "MFH" <mfh01 at bigpond.net.au>
To: "'Greg and April'" <gregandapril at earthlink.net>; "'Kevin Chisholm'" <kchisholm at ca.inter.net>; "'Terra Preta'" <terrapreta at bioenergylists.org>
Sent: Thursday, May 15, 2008 15:36
Subject: RE: [Terrapreta] Let's talk retort materials for a little bit


SNIP

> 
> Chimney routing - absolutely from the base before rising. Take it
> horizontally for a while before rising and use the heat to pr-dry the next
> batch.
> 
> M
> 
> 
> 
> 
> -----Original Message-----
> From: terrapreta-bounces at bioenergylists.org
> [mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Greg and April
> Sent: Thursday, 15 May 2008 11:51 PM
> To: Kevin Chisholm; Terra Preta
> Subject: Re: [Terrapreta] Let's talk retort materials for a little bit
> 
> I'm willing to put up with a little cost to gain some efficiency and life. 
> I don't want to use more than 1/4" of material, since thinner walls improve 
> thermal efficiency.    I figure that some warping is fine, and not really 
> going to change the overall efficiency.
> 
> Temperature will be fairly uncontrolled, unless/until a thermocouple and 
> damper is installed.
> 
> I am planning on a layer of castable refractory on the inside of the outer 
> shell, so it will have a layer of protection and so it can be of lesser ( 
> cheaper ) material.
> 
> I am thinking about improving thermal efficiency by routing the chimney so 
> that it dips below the level of the retort, before going up as it normally 
> would - in this way the heat builds up around the inner shell, before 
> exiting.
> 
> 
> Greg H.
> 
> 
> ----- Original Message ----- 
> From: "Kevin Chisholm" <kchisholm at ca.inter.net>
> To: "Greg and April" <gregandapril at earthlink.net>
> Cc: "Terra Preta" <terrapreta at bioenergylists.org>
> Sent: Wednesday, May 14, 2008 15:07
> Subject: Re: [Terrapreta] Let's talk retort materials for a little bit
> 
> 
>> 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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