[Stoves] Belonio burner top on TLUD stoves was Re: radiant heat capture, total heat measurement

Paul Olivier paul.olivier at esrla.com
Fri Mar 16 18:43:44 CDT 2012


See comments.

On Fri, Mar 16, 2012 at 11:56 PM, Crispin Pemberton-Pigott <
crispinpigott at gmail.com> wrote:

> Dear Paul A
>
> I think quite a bit more experimentation is needed before copying the top
> end of Alexis' burner.


In this sentence, you use the word "before".
Why not skip the "before: and begin experimenting "with" the Belonio burner?


> The evolution is that it was not a premixed flame and
> the structure was built with that in mind. The change to a premixed flame
> was not matched by a change in the structure.


I do not understand what you are saying here.


> The result is that there is a
> very high excess air rate passing through the underside and emerging by the
> pot. This has the effect of heating a lot of air and lowering the gas
> temperature beside the pot.
>

Why do you think that there is necessarily a "very high excess air rate"?
I would agree that the Belonio burner all by itself might have a high
excess air rate.
That is why I designed a housing around the burner,
 and this housing is surely not the best that could be done in this case.
After the housing there is still another part needed to limit excess air.

Of course one could design a true premix burner and situate this on top of
the reactor.
Here a distinction would be made between the lid of the gasifier and the
burner.
The two would no longer be the same.
But air entrainment before burning the gas requires pressure,
 and pressure requires gaskets that do not leak,
since gaskets that leak are quite dangerous.
I suppose that pressure has to be controlled with a high degree of
precision.
This might call for a fan with a good speed regulator.
But with a fan, the unit is no longer natural draft.

You are right: with a lot of excess air, combustion might be good, but heat
transfer might be poor.
The dome looked so promising from the point of view of limiting excess air.
And now without the dome, I am testing the design of still another part
 that limits excess air and protects the flame from wind.

Thanks.
Paul Olivier



> I feel that a 30% improvement in heat transfer efficiency can be achieved
> by
> addressing this issue.
>
> I have noticed that stove builders fall roughly into two groups: those who
> build high neat transfer efficiency stove bodies but with mediocre
> combustion, and those who make really good combustion but neglect the
> detail
> of getting good heat transfer. In some cases there is a sort of blind
> adherence to the idea that a fuel is 'clean' and there is no need for
> either. 'Clean burning means efficient,' which is nonsense.
>
> We should all be paying a lot of attention to both aspects of stove
> building: efficient combustion and efficient heat transfer. One does not
> automatically derive from the other.
>
> Regards
> Crispin
>
>
> -----Original Message-----
> From: stoves-bounces at lists.bioenergylists.org
> [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Paul S.
> Anderson
> Sent: Friday, March 16, 2012 6:07 PM
> To: Discussion of biomass cooking stoves; Paul Olivier
> Cc: zong at ilstu.edu; Belonio - Philippines; Corey Berman; Hugh McLaughlin;
> Bob Fairchild; Alexis; Chua He
> Subject: [Stoves] Belonio burner top on TLUD stoves was Re: radiant heat
> capture, total heat measurement
>
> Dear all,
>
> Paul Olivier commented:   (full message is still below, with link to a
> photo)
>
> > ..... which has always led me to wonder  why the Belonio burner hole
> > pattern was not adopted on natural draft units.
> > If a burner housing were added, I think the unit I experimented with
> > would work much better.
>
> Paul O. raises an excellent point.  I think that the moderate complexity of
> the Belonio hole pattern and secondary air inlet (contrasted to simple
> concentrator hole) has kept me and probably most others from experimenting
> with it.  Perhaps we incorrectly associated it too much with the forced air
> (Fan Assisted = FA) aspects of Belonio's rice husk gasifiers.
>
> Very little is known about the tops of TLUDs except that some amount of
> constriction is needed to force the mixing of air and gases.
>
> I hope that the engineers (such as Bob Fairchild and student
> engineers) and others who are now working on TLUD stove issues will
> seriously consider the Belonio top and related enhancers of combustion of
> the gases.
>
> Paul    (Paul A.; not to be confused with Paul O.)
> --
> Paul S. Anderson, PhD
> Known to some as:    Dr TLUD      Doc      Professor
> Phone (USA): 309-452-7072   SKYPE: paultlud   Email: psanders at ilstu.edu
> www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf (excellent ref.)
> My website specific for TLUD information: www.drtlud.com  =
> www.DrTLUD.com
>
>
> Quoting Paul Olivier <paul.olivier at esrla.com>:
>
> > Kevin,
> >
> > You say:
> > *# OK!! A 50% reduction in boiling time is very significant.
> > What can you now tell us that will enable us to apply it to other stoves
> > and combustion conditions?*
> >
> > I once did an experiment in which I made the 150 Belonio about half its
> > original height.
> > I then filled it with chunks of wood and put a Belonio burner on top.
> > This was a natural draft unit without a fan.
> > This is what it looked like:
>
> > http://dl.dropbox.com/u/22013094/150%20Burner/Image2097.jpg
>
> > But looking back on this, I see that there were so many problems with
> this
> > burner,
> >  even aside from the fact that it had no burner housing.
> >
> > You raise an interesting question, though, which has always led me to
> wonder
> >  why the Belonio burner hole pattern was not adopted on natural draft
> units.
> > If a burner housing were added, I think the unit I experimented with
> would
> > work much better.
> > The central problem that I see with a natural draft unit is an uneven
> > upward flow of primary air.
> > At times too much CO2 is created, and some burner holes lose their
> flames.
> > Also I would imagine that the inlet of primary air has to be strictly
> > control to get a consistent outlet of gas at the burner.
> >
> > A natural draft TLUD is very complicated,
> >  and I truly marvel at those who get them to work on such a broad variety
> > of fuels.
> >
> > Thanks.
> > Paul
> >
> > Thanks.
> > Paul
>
>
> ----------------------------------------------------------------
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>
>
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-- 
Paul A. Olivier PhD
27C Pham Hong Thai Street
Dalat
Vietnam

Louisiana telephone: 1-337-447-4124 (rings Vietnam)
Mobile: 090-694-1573 (in Vietnam)
Skype address: Xpolivier
http://www.esrla.com/
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