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

[Anand Karve]

Dear Crispin,

Our kiln is just an enlarged version of our Sampada stove. It consists
of two chambers, one inside the other. The inner chamber holds the
biomass, which is ignited from the top. The primary air is supplied by
holes at the bottom of this chamber. The outer chamber surrounds the
inner chamber, but there is a gap of 2.5cm between the two chambers.
Secondary air is supplied through this gap. We get about 30% char in
this kiln, whereas in the case of the oven-and-retort kiln, we got a
yield of only 20%. The new design works quite well with sugarcane
leaves, but with smaller leaves, the primary combustion can get choked
to congestion of the biomass.

Yours A.D.Karve
***
Dr. A.D. Karve

Chairman, Samuchit Enviro Tech Pvt Ltd (www.samuchit.com)

Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)


On Sun, Feb 15, 2015 at 5:26 PM, Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:
> Dear AD
>
> Very interesting. Are you using the drums 'as is' without the encompassing
> shell and cover? Does the TLUD process yield less char?
>
> I would appreciate seeing a description of the new system.
>
> Thanks
> Crispin in Monsoon Yogya
>
>
> Dear Crispin,
> we no longer use the oven and retort process for charring agricultural
> waste but use the TLUD principle, because the old oven and retort
> process required more hardware, resulting into higher capital cost.
> Yours
> A.D.Karve
> ***
> Dr. A.D. Karve
>
> Chairman, Samuchit Enviro Tech Pvt Ltd (www.samuchit.com)
>
> Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)
>
>
> On Fri, Feb 13, 2015 at 5:52 AM, Crispin Pemberton-Pigott
> <crispinpigott at outlook.com> wrote:
>> Dear Jock and Paul and All
>>
>> This is conceptually very similar to what Dr AD Karve has been doing with
>> the sugar cane leaves except for two things. He is using 7 barrels at a
>> time
>> in the fire and the gas exits the bottom of the containers (barrels) so as
>> to use the heat for cooking the char instead of cooking the pot.
>>
>> The Karve Koncept uses the least total fuel to make the char (the primary
>> product). The capping of the top to keep air out and heat in allows for
>> simultaneous cooking but requires more fuel (to make the char) but has a
>> second task to accomplish so it doesn't matter.
>>
>> In both cases the systems are able to make char from material that is hard
>> to work with. In the second case an 'easier to burn fuel' is used to char
>> a
>> 'hard to burn fuel'.
>>
>> When sawdust is used for cooking it is often burned using the 'central
>> hole' drum approach with a stick forming the hole while it is packed
>> around
>> with sawdust. A second stick makes the side air entrance.
>>
>> Cecil reports that a standard way of having that approach not have to burn
>> at high power all the time and to reduce the smoke bursts is to put a
>> single
>> stick of fuel into the side hole where it provides a continuous ignition
>> source for the gases inside. This burns slowly and is pushed in now and
>> then. Viewed systemically it is also a co-firing burner that uses a
>> different fuel to maintain the production and burning of the gases.
>>
>> Most practical cooking stoves have some measure of power control. As this
>> approach is micro-tized please consider how it might be controlled up and
>> down. For space heating it is not much of a requirement so a MPFront would
>> suit the power requirment well.
>>
>> Regards
>> Crispin in the Monsoon
>>
>> Paul,
>>
>> I will try to answer your questions from the perspective of a teaching
>> tool,
>> not a production unit.
>>
>> Cheers,
>>
>> Jock
>>
>> Jock Gill
>> P.O. Box 3
>> Peacham,  VT 05862
>>
>> +1 (802) 503-1258
>>
>> Stewardship: not dominion, extraction or exploitation
>>
>>
>> On Feb 12, 2015, at 11:53 AM, Paul Anderson <psanders at ilstu.edu> wrote:
>>
>> 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.
>>
>>
>> My approach is to simply place the retort can on the bottom of the empty
>> TLUD - centered.  I have the primary air come in from the sides, not the
>> bottom, to avoid cooling of the lower portion of the retort.  The top of
>> the
>> retort can is at about at the level of the secondary air supply, perhaps a
>> bit below.
>>
>> Then I fill the space between the retort can and the TLUD with fuel -- I
>> use
>> wood pellets for demos.
>>
>> Start the TLUD in the usual fashion.
>>
>> When the TLUD has pyrolized the last of the pellets, the retort is left
>> sitting in a very hot bed of charcoal that reaches part way up its sides.
>> I
>> allow the charcoal to continue to burn, with primary air, until the retort
>> is finished -- no more combustible gases coming out.  While the charcoal
>> is
>> burning, the upper part of the retort is bathed in very hot exhaust gases.
>> Thus it is important (?) that the top of the retort can be below the
>> cooling
>> secondary air.
>>
>> At the end, since both the TLUD and the Retort are small, it is not
>> difficult to extract the retort can and then dump the charcoal remaining
>> in
>> the TLUD into quenching water.  I sometimes empty the retort into a mason
>> jar and seal it in the usual way.  This gives me bone dry biochar.
>> Quenching hot biochar in water gives me instantly fully saturated
>> [hydrated]
>> biochar - or so says Hugh.  It is also safe to handle and will not
>> spontaneously re-ignite.
>>
>> Keeping the retort in the the TLUD, below the secondary air, and away from
>> the primary air, both of which would tend to cool the retort, seems to
>> work
>> well.
>>
>> Note:  Wood pellets work well in my system.  Larger grass tablets seems to
>> be have a more difficult time transferring heat inside the retort.
>> Perhaps
>> part because they expand when they get hot?
>>
>> In my educational units, the TLUD is a large coffee can from Costco - very
>> nice steel.  The resort is a 1 quart paint can - not such nice steel. BTW,
>> you  only need two or three holes in the lid of the 1 quart can to allow
>> the
>> gases out.  I suspect this also helps to keep heat in the retort.  The
>> escaping gases will take heat away as they exit the retort - yes?
>>
>> I hope this helps.
>>
>> Cheers,
>>
>> Jock
>>
>>
>> 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
>>
>> :> Extract CO2 from the atmosphere! <:
>>
>> Via iPad
>>
>> On Feb 12, 2015, at 5:07 AM, Marquitusus <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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