[Stoves] Retort can inside TLUD gasifiers Re: Fine particles as fuel in TLUDs

Thu Feb 12 10:53:20 CST 2015

To all,   both Stovers and Biochar makers.

I thank Marc and Jock and Kirk (and probably some others, including 
Peter Hirst with his barrel-size unit, on video) for their efforts with 
a retort can inside of a TLUD gasifier.   (see some messages below).   I 
mention the following topics for consideration.

1.  Where inside the TLUD is the retort can to be placed?   The retort 
needs heat to it, but the TLUD _heat _INSIDE THE FUEL BED is only at the 
top and then progressing slowly downward with the MPF (Migratory 
Pyrolytic Front), meaning that the bottom of the can does NOT get heated 
until the MPF is getting close.

Therefore, should the retort can be above the fuel level but below the 
entry of secondary air?   Maybe not, because the can and its contents 
could chill the rising gases and hinder their combustion.  But maybe 
this is not so crucial?

Maybe the retort can is only in the upper half(?) of the TLUD fuel?

Or maybe this does not make much difference?

2.  I like Jock's idea of the outlet holes being upward in the retort 
can.   He reports seeing the small jets of flame.   That means that the 
retort gases are entering into an environment with sufficient secondary 
air for combustion.   This also is then an issue of the placement of the 
retort.

Please note that instead of outlet holes there could be an outlet 
Channel (pipe, tube, etc) that takes the retort gases to a different 
place.   Remember that retort gases come out in a sequence of types that 
start with water vapor, then mixed gases, and finally the pyrolytic 
gases that are combustible.   Retort processes do not occur the same way 
as TLUD processes.

3.  Placing the retort canister ABOVE the secondary air entry provides 
the maximum heat to the retort.   Maybe it could be in the "riser" 
section, or up where the cooking pot would otherwise be placed.   This 
has been done in barrel-size units by Doug Clayton and Hugh McLaughlin 
and is on video.  The main problem encountered is the difficulty / 
danger of handling full barrels well above ground level, sometimes full 
of hot char.

4.  Of course, issues of char qualities need to be considered. About 
putting fines (very small) biomass into retorts, it is known that the 
transfer of heat from the edges to the center is HINDERED if the 
materials are too packed together.

Many of us are looking forward to further reports on this topic.

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu
Skype: paultlud      Phone: +1-309-452-7072
Website:  www.drtlud.com

On 2/12/2015 6:35 AM, Jock Gill wrote:
> Marc,
>
> I have also done this.  I place feedstock in a smaller can that only 
> has a few holes in its lid to allow the pyrolytic gases to escape and 
> burn.  I then place this, as you did, in a larger can used as a ND 
> TLUD and surround the smaller can with fuel.  This creates a retort 
> within a TLUD.  The TLUD will burn some of the charcoal it has made in 
> order to finish the pyrolysis in the inner retort can.
>
> I find, contrary to the given wisdom, that the inner "retort" can be 
> placed with in the TLUD with the gas escape holes facing UP.  This 
> allows students to see the gas come out and ignite.  If they can see 
> the flames created by the gas coming out of the retort it much more 
> powerful  educational experience.
>
> Well done,
>
> Jock
>
> Jock Gill
> P.O. Box 3
> Peacham,  VT 05862
>
> Cell: (617) 449-8111
>
> google.com/+JockGill <http://google.com/+JockGill>
>
> :> Extract CO2 from the atmosphere! <:
>
> Via iPad
>
> On Feb 12, 2015, at 5:07 AM, Marquitusus <marquitusus at hotmail.com 
> <mailto:marquitusus at hotmail.com>> wrote:
>
>> Hi, in the mids December I consulted the list about my problems with 
>> almond husks as TLUD's fuel.
>> The problem is the smaller particles of this fuel obstruct the 
>> primary air flow and the pyrolisys stops.
>>
>> Kirk suggested me using the "can method": just screening the fuel and 
>> use the smaller fraction for filling a can that will be put inside 
>> the reactor, surrounded by the large particles fraction. I recently 
>> tried this method, and it really worked! You can see pics here: 
>> http://cuinessolars.jimdo.com/cuines/cuines-gasificadores/
>>
>> So, this opens the door for using any size of fuel in a ND-TLUD, from 
>> rice hulls to saw dust or any other little particles fuel ( I 
>> understand that in a FD-TLUD is not necessary, because of the forced 
>> air draft). Also, this method can allow to shorten the size of the 
>> chimneys or risers, because less draft is necessary.
>>
>> The bad news are we need a can (that is exposed to high temps that 
>> will deteriorate it) and we need to previously screen the fuel, but I 
>> think these are minor handicaps compared to the benefits it brings
>>
>> Marc
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