[Stoves] [Biochar] Rocket stove design for retort heating #rocketstove #retort

[ajheggie at gmail.com]

From: K McLean <kmclean56 at gmail.com>
Date: Mon, Jan 4, 2021 at 1:42 PM

We designed the AGWA, a crude TLUD (<$2) for very poor households in
developing countries.  It works well with maize cobs as fuel and makes
biochar.  Hundreds of women are now using the AGWA and like it.  We
are testing a larger version for use in school kitchens.

We are also revisiting sawdust stoves.  They burn long and clean
without tending.  They are cheap to make and easy to use.  And they
make a lot of biochar.  We are testing with crop residues and are
having success.   I'm sure sawdust stoves can be adapted to
institutional settings.  Sawdust stoves have been used for decades.
I'm not sure why they are not ubiquitous.

We are also training farmers to mix the biochar with urine to use in
their fields.

Kevin McLean
Sun24



On Sun, Jan 3, 2021 at 6:36 PM Ronal Larson <rongretlarson at comcast.net> wrote:
>
> Trevor and biochar list with 5 ccs:
>
> Inserts below but first:  why I’ve added 5 more .  (all with whom I ‘ve had multiple valuable conversations; and all in this area as volunteers - not needing to make a profit - and all I believe highly willing to share biochar (and stove/retort) experiences )
>
> Kevin(FL):  Sees a need for something like you are designing for the large cook pots (200 liter or more?) now often/mainly using 3 rocks in many rural public schools - especially in Africa.
>
> Ken (OR):  Has written a great report on using 200-liter barrels/drums, not as TLUDs or retorts, but split to enclose something like a really large flame-cap Kon-Tiki
>
> Bill (NM):  Has built and tested a char making TLUD bigger than yours  both in diameter and height.  Not a retort above a TLUD, but similar issues below.
>
> Norm (WA);  has the best knowledge I know re 200 liter barrels/drums as TLUDs
>
> Kirk (CA);  Has designed a large TLUD for use with planchas - with run time exceeding 2 (3?) hours
>
> Your  5-point description below is first rate.  I hope Kevin, Ken, Bill, Norm, and, Kirk will add to my thoughts.
>
> This is an important topic.
>
> Needs to be on the stoves list as well. (I’ll send next.)
>
>  Last remark reminds me there is a new beginning ISO effort on how to rate and rank stoes above 150 liter cook-pot size  - and you might find thatt helpful or vice versa.
>
>
> On Jan 3, 2021, at 2:00 PM, Trevor Richards <trevor at soilcarbon.org.nz> wrote:
>
> Hi Paul,
> This is an option being considered & was also suggested by Ron. These are some design considerations:
>
> The pressure vessel we have for conversion to retort is 1000mm between dome ends & 800Dia (~500L). Current idea is to elevate retort to comfortable access height on its side (say 1m above ground) & fabricate swing door from one dome end. This gives 1m to play with under the retort. This could be extended with a pit but then we are handling TLUD's below our feet or in a trench or we house separately and duct heat/gasses to the retort furnace chamber.
>
> [RWL1 - should work.
>
>  I have been thinking with Kevin of the lower part of a vertical 200 liter drum/barrel operated as a TLUD that would sit under your “pressure vessel”, whose height above ground would then be less than a meter (as are 200 liter drums).
>
> The additions we have been considering to your TLUD thinking below is an added skirt whose height will cover both the lower TLUD and the upper “cook-pot/retort”.  Separating primary and secondary air has many possible alternatives.  We can discuss that more, if you wish.
>
> Need to be able to extract (swap out?) a hot TLUD from the furnace chamber to quench.
>
> [RWL2:  Yup.  Your upper retort is too big to move as one with a cook pot above a small TLUD.  I’ve been thinking of sliding the big TLUD out - maybe on rails if needed. Of course needs to have a smaller  OD than your retort.
>
> TLUD would need to be sized to complete the retort heating phase ... how to size & design based on limitations
>
> RWL3:  Yup   Same issue for Kevin, Bill  and Kirk (not Norm and Bill)
>
> A rocket stove could more easily fit within space available & be kept fed until gas ignition but maybe slow & labor intensive... again, how to estimate fuel load needed for our retort?
>
> [RWL4:  Yup.  A cook pot can’t give off useful gases as can your retort design, so you might not need too much “stove” below - especially with a skirt (which will help on operator comfort, speed ,and efficiency.
>
> Could assume 200-300kg of wood @25-35%MC when loaded.
>
> [RWL5:  All of the above experts can help with that estimate.  Use maybe 15 MJ/kg  (wet) wood, use maybe density of .6 or .7?   Kevin will recommend much lower density corn cobs because of cost.  I have never seen a good analysis of energy needed for your sort of  retort.   Anyone on the list cable to give Trevor and estimate based on his 200-300 kg size/shape retort.
>
> In sum,  I hope you stick with the TLUD over the Rocket
>
>
> Good luck.  Keep us informed.
>
> Ron
>
>
> Your comments appreciated.
>
> On Mon, 4 Jan 2021 at 09:08, Paul S Anderson <psanders at ilstu.edu> wrote:
>>
>> Trevor,
>>
>>
>>
>> Why not start your retort with heat from a TLUD that will give you 70% of the heat and a lot of char in addition to what you get from the retort?
>>
>>
>>
>> Paul
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>
>
>
>> From: main at Biochar.groups.io <main at Biochar.groups.io> On Behalf Of Trevor Richards via groups.io
>> Sent: Friday, January 1, 2021 4:57 PM
>> To: main at Biochar.groups.io
>> Subject: [Biochar] Rocket stove design for retort heating #rocketstove #retort
>>
>> Looking for advice on designing a rocket stove to provide startup heating for a 500L retort.
>> The plan is to cut one dome end off a steel pressure vessel to create a door. The vessel (Dia~0.8, L~1.0m) would on its side within a well insulated fire box. The idea is to use a rocket stove under the retort until gas ignition is sustained. I assume this has been tested before so I'm interested in...
>>
>> guidance on H&MB calcs to estimate heating time to gas ignition, based on some typical wood biomass assumptions
>> design & sizing of rocket stove (will it even be practical heating solution).
>>
>> supplement with a small TLUD to kick off retort heating?
>>
>>
>> comments & suggestions welcome.
>> Thanks, trevor
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