[Stoves] Designation of TLUD gasifier devices.

Crispin Pemberton-Pigott crispinpigott at outlook.com
Mon Sep 21 07:31:30 MDT 2015


Dear AD

Do you agree that what you describe, when it is running, is a bottom-lit updraft gasifier?

Crispin


Dear Crispin,
In India, there are many stove models which are ignited at the top
like a TLUD stove. The primary air comes through a grate at the bottom
of the stove, and the secondary air is introduced into the flame to
burn the gases completely. The secondary air is provided either by
natural draft or by means of an electrically driven fan. These stoves,
whether with a fan or without, can be fed continuously from the top
and the ash can be continuously removed from the bottom. Some time
ago, when I called such a stove, a TLUD stove, Paul asked me not to
use the term TLUD for such stoves. So we describe our model, which we
are marketing, as a gasifier stove. Your explanation has cleared the
air.
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 Mon, Sep 21, 2015 at 11:20 AM, Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:
> Paul
>
>
>
> You just can't just make stuff up.
>
>
>
> We talked about this years ago and the direction of gas flow is the first
> categorisation of devices. If you have included in your book that a TLUD
> which does not separate gas combustion from the gas generation is not a
> TLUD, even if it is, you will have to change the book.
>
>
>
> You can easily have a bottom lit downdraft stove that is not a gasifier. You
> can just as easily have one that is - depending on whether there is a
> pyrolysis zone that is very short of air and is creating gas at a rate that
> it cannot burn within the fuel bed. The gas escapes and burns below the
> grate.
>
>
>
> Wood can be burned in both modes in a downdraft fashion. It can just as well
> burn upwards in both modes. The difference between them is related to the
> air flow and O2 availability in the gas generation zone, do you agree?  Tom
> Reed proposes that the superficial velocity of the air dictates whether the
> system is a pyrolyser or a gasifier.
>
>
>
> ‘Any old fire' is not a characterisation of gas flow direction or the
> separation of generation from final combustion.
>
>
>
> I would hold that there are three states: TLUD burning, TLUD gasification,
> and TLUD pyrolysation. Exactly the same divisions can be made for cross
> draft and downdraft combustors.
>
>
>
> To my surprise I found out from Hirendra in India that he is making BLUD
> gasifiers - lots of them, and big too. I had never heard you talk about this
> layout. The fire is on the bottom and the MPF is rising through the fuel,
> the flow of air and gases is upwards. The fuel is continuously added from
> the top, and the ash is removed from the bottom. It runs continuously 24/7.
>
>
>
> That is clearly a BLUD gasifier, as it does not produce charcoal so it is
> not a pyrolyser. Do I have that correct? I am following your lead on this.
> It is not a TLUD and it is refuellable which is a very big deal.
>
>
>
> It means you could be having a micro-gasifier that is refuellable (from the
> top or just to the side), while creating gases that rise to a combustor
> above the top – clear separation from the gas generation zone. It does not
> have a hot char zone through which the gases rise. How is it we have not
> heard this system being described here before? He has been making them for
> years.
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
> Dear readers,
>
>
>
> All readers are advised that some people insist on using a valid GASIFIER
> term of TLUD when referring to other types of fires because there is
> ignition at the top of a fuel pile and the air flow is
>
> upward.   And they do this without regard to the GASIFIER structure that
>
> allows the creation of the gases to be separate in time and space from
>
> the burning (or other usage) of the created gases.   The creation and
>
> the burning of the gases can be very close, but they CAN be separated.
>
> For example, the top flame (the secondary combustion) can be extinguished in
> a TLUD gasifier (but not in just any old bucket or open fire).
>
>
>
> Paal Wendelbo observed the Norwegian resistance fighters having top
>
> lighting of open campfires, and they were not using gasifier devices.
>
> 40 years later he contained that pyrolysis and gas burning processes inside
> metal cylinders and had the start of what is today called TLUD gasifiers.
>
>
>
> Today, after 30 years of development of TLUD stoves and other true
> micro-gasifiers that now have respectable recognition, it is becoming trendy
> to call other things TLUDs when they are not or are mere shadows
>
> of what is involved with gasifier stoves.   There are no "terminology
>
> police" or copyrights on TLUD.   Readers need to be aware of the details
>
> of the actual operations, regardless of what it is being called.
>
>
>
> Readers are encouraged to use as a reference the book on
> Micro-gasification.... by Christa Roth (GIZ publisher) and my article
> "Micro-gasification Terminology...", both of which are available in the
>
> Quick Picks list on my website   www.drtlud.com
>
>
>
> I did not invent TLUD gasifiers, but I did give them that name 10 years
>
> ago.   People can use the words top lit and up draft to describe other
>
> things, but the acronym TLUD should appropriately refer to a reasonably well
> defined TYPE OF GASIFIER DEVICE, most specifically as a cookstove or
> char-maker.  Use of that TLUD designation for other devices is a form of
> mimicry and getting on a bandwagon, or worse, which is just to make
> confusion.
>
>
>
> Dr TLUD
>
>
>
>
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