[Stoves] Understanding TLUDs, MPF and more. (was Re: Bangladesh TLUD )

[Paul Anderson]

Crispin,    see below.

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 12/11/2017 9:56 PM, Crispin Pemberton-Pigott wrote:
>
> Dear Paul
>
> I am surprised by the description of charcoal combustion offered 
> below. If you hold that a TLUD is making a combustible gas then 
> burning it separately, would you not also apply this same definition 
> to charcoal?
>
Certainly not.   And you provide the reason for  the difference. You 
point out (next lines that are your writing) that char-gasification 
occurs directly on the surface of the char.  So there is no movement of 
a gas (supposedly CO?) to a different position where it is combusted to 
CO2.
>
> A charcoal gasifier, such as that produced by YDD in Yogyakarta, is a 
> TLUD that makes CO. A charcoal burner might make gas first and might 
> now. Carbon will go directly to CO2 on the surface of the char above 
> 400 C with a probability of about 6/7. The other 1/7 it goes to CO.
>
> A bottom-lit updraft charcoal fire like a BBQ is fundamentally 
> different from a charcoal gasifying TLUD making CO, don’t you agree?
>
Again, no.   Both are piles of hot charcoal that are receiving air from 
underneath.   With equal amounts of air from underneath, both would make 
CO2 and CO is similar amounts.

The TLUD is not trying to create CO that will rise to then be burned 
where the secondary air enters. If that actually functioned well, we 
would expect to see a nice light blue flame of CO combustion at the 
level of the secondary air entry, which does not happen.

When air comes up under the hot char, there is char gasification that 
does not selectively stop at CO instead of going to CO2. (Reference:  
Your statement above about 6/7ths going to CO2.    I do not know the 
original source, but I will accept your statement as correct until shown 
otherwise.)

Do you accept my comments as correct?   As you have said at other times, 
established science is not subject to a vote.

Paul
>
> Thanks
> Crispin
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On 
> Behalf Of *Paul Anderson
> *Sent:* 12-Dec-17 08:07
> *To:* Discussion of biomass cooking stoves 
> <stoves at lists.bioenergylists.org>
> *Subject:* Re: [Stoves] Understanding TLUDs, MPF and more. (was Re: 
> Bangladesh TLUD )
>
> Dear Scott and Todd,       (another of 3 replies to about a dozen 
> messages on this topic.  Not in any special order.  I thank everyone 
> for their comments.)
>
> The essence of TLUD operations is the pyrolysis stage.  Stoves that 
> are true TLUDs and THEN continue to consume the char (which is called 
> "char gasification") will end up with only ash.  They were operated in 
> two ombustion modes (first was TLUD pyrolysis, and second was charcoal 
> burning).  Those could be valid as stoves, but the second mode should 
> be noted, and not simply called TLUD only stoves.
>
> The other type of stove is the "fan jet" or high vortex stoves like 
> the Philips /ACE, which are designed to push plenty of secondary air 
> downward onto the top of the created char, with the result of very 
> little char production.   I prefer to not call them TLUD stoves, and 
> instead use a name that is appropriate to recognize the distinctive 
> way those stoves work, which may be more desireable to some people.  
> Why call it a TLUD and not take credit for the powerful fan features?
>
> Todd might specifically identify which stoves he is mentioning.  [That 
> would be a very appropriate discussion of the stoves that he is able 
> to provide to interested people. And DO include the prices.]
>
> Ron's comments about the 3 main ways of handling the char (his message 
> dated 10 Dec) is well stated. (He asked for my opinion.)
>
> Paul
>
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:psanders at ilstu.edu <mailto:psanders at ilstu.edu>
> Skype:   paultlud    Phone: +1-309-452-7072
> Website:www.drtlud.com 
> <https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.drtlud.com&data=02%7C01%7C%7C6fd7255756764eba5e3908d54105804a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636486414232512073&sdata=OugKAl%2BAmoXbvfooVGjZ20b4q2VIOeOuf9ph4Bb129c%3D&reserved=0>
>
> On 12/10/2017 2:25 PM, Scott Zager wrote:
>
>     Thank you for helping a novice along. Todd has help clarify that
>     there are many types of TLUDs. Are they all intended to be
>     gasifiers with a secondary combustion chamber or collection tank
>     for wood-gas? Is it still pyrolysis if the stove combusts char to
>     ash?  Perhaps I should continue reading the literature.  Thanks
>     again for your patient assistance.
>
>     Scott Zager
>
>     *From:* Stoves [mailto:stoves-bounces at lists.bioenergylists.org]
>     *On Behalf Of *Todd Albi
>     *Sent:* Sunday, December 10, 2017 1:05 PM
>     *To:* Discussion of biomass cooking stoves
>     <stoves at lists.bioenergylists.org>
>     <mailto:stoves at lists.bioenergylists.org>
>     *Subject:* Re: [Stoves] Understanding TLUDs, MPF and more. (was
>     Re: Bangladesh TLUD )
>
>     Scott:
>
>     Different TLUD stoves are designed to accomplish different tasks. 
>     There are TLUDs  designed for different tasks.  Char production
>     will differs considerably from one design to another.  Many high
>     efficiency TLUDs designed for wok cooking produce minimal, if any
>     char.  There are lots of fan assisted TLUDs and natural draft
>     TLUDs, designed for cooking that produce minimal char, only
>     minimal fine ash. Therefore your glossary is incorrect leading off
>     with the statement /TLUDs automatically make char/ would be
>     incorrect for many TLUDs that are designed for cooking.  Although
>     there a number of natural draft cooking TLUDs designs too, that
>     the definition maybe be somewhat accurate for.  Our organization
>     has several TLUDs designed for cooking that produce only a thimble
>     full of fine ash after cooking.  Those cooking implements
>     obviously would no value for a stover, who sits on the bio char
>     production interest side of the fence.
>
>     Many of the stove designs on this list have variable design
>     advantages, disadvantages, /depending on desired performance
>     outcomes/ of stove design.   I'd contend more complicated
>     combination cooking and thermal siphon heating stove designs,
>     typically compact stove designs with fans, large combustion
>     chambers, and water tanks, would not be viable transferring heat
>     into larger volumes of water (high mass), if designed to produced
>     char at the same time.  Large volumes of char would impede
>     ventilation and heat transfer, that is required to maximize heat
>     transfer into the water.  Heating the water would be the greater
>     energy task,  to reach the desired goal of thermal siphoning in
>     this simplified example.  In this type of stove, char production
>     would reduce stove thermal efficiency required to maximize heat
>     transfer to the water tank.
>
>     Regards,
>
>     Todd Albi, SilverFire
>
>
>
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