[Stoves] Low cost charcoal gasifiers

Crispin Pemberton-Pigott crispinpigott at gmail.com
Sun Sep 30 08:29:57 PDT 2012


Dear Paul

 

It is sorta funny so I have to point it out: 

 

"... and then use phrases like "...in use (as I understand it) in the UK for
a long time before 

that..."       "

 

I was referring to the use of the UK of downdraft gasification plants which
supplied coal gas to municipalities. Please read it again.

 

Here is your information: (from
http://shop.silver.com.tr/?icerik/512/0/The-Profile-of-the-Company- watch,
the English is a bit mixed up.)

 

"Dökümiş Co. Ltd. which was established in 1958 produces Silver branded
stoves. It has the manufacturing capacity of 90.000 unit/year solid fuel,
50.000 unit/year LPG stove, 500.000 unit/year pipes and bends. Our factory
which is located on 47.650 m2 has 20.500 m2 indoor area."

 

'Silver' is the marketing company, officially called Silver Trade Inc. which
was formed in 1982.  All their solid fuel stoves are TLUD's. They burn both
coal and wood. They are working overtime I think. They had only a 40,000
TLUD stove capacity in 2010. It has been increased because of Mongolian
sales.

 

The stoves all have an unusual grate which is circular, and mounted on a
central pivot. 

 

Description: cid:image005.png at 01CD9E97.95786C80

 

A handle can be used to shake it in a rotating fashion. In addition, pulling
a pin outwards allows the grate to flip over 180 degrees, dumping all
accumulated clinkers and stones into a large tray underneath which is housed
in a sealed door (the body is very gas tight).

 

Note the vertical grooves in the ceramic chamber that pipe air up to the top
to serve as secondary air. This is not done in any of the small TLUD's that
I have heard about. Perhaps you have seen it. This preheats the air as it
passes through the pyrolysation deck. As it comes from professionals with
50+ years of experience it is perhaps something other producers should
consider. 

 

They manufacture 25 types of solid fuel stoves plus LPG and natural gas
models. Many of the wood/coal stoves will operate for 24 hours unattended
when loaded with about 15 kg of coal. Other models are suited to a 12 hour
burn which is the need in some of their region (Turkey).

 

This is a pot on the stove with the flames directly underneath:

 

Description: cid:image002.jpg at 01CD9EA7.6710E560

 

And here is a front quarter view of their smallest unit, about 7 kW. I have
tested this one. It was more than 99% cleaner than the baseline stove+burn
cycle, burning the same unprocessed lignite (Nalaikh Mine coal).

 

Description: cid:image004.jpg at 01CD9EA7.6710E560

 

There is another larger model visible in the right corner.

 

So with regard to claims, I feel everyone needs to prove they are correct
when making sweeping statements about names and origins. There is no
'default' correct position, especially in the face of alternate claims from
various quarters.

 

For the benefit of others I will include some photos here so it is clear
what we are talking about.

 

John's original stove is similar to all the current crop of TLUD's save that
it had more holes drilled into the fuel holder at various heights. The
lowest portion of the stove (the cylinder) has an open bottom with the fuel
sitting on a fine mesh. This aspect is unlike the TLUD's which strictly
control air access to the fuel from the bottom.  The addition of a secondary
preheater around the outside of the upper portion of the fuel hopper
improved the combustion quite a bit. If he had a ceramic liner, he could use
the internal groove method instead but that would mean a change in the air
and draft control. I believe he gets a 6 hour burn with the standard sized
ones. I think Tom Reed would call it a packed bed gasifier, right? John says
that is its correct description.  It depends on the fuel packing to restrict
the upward air flow through the fuel, not external bodywork and a regulated
air hole like the Silver (and others).

 

Description: cid:image010.png at 01CD9E9A.85955140

SeTAR Centre test 2008

 

In this later model the row of horizontal holes is a power regulator,
controlling air entry into the secondary air heater. By bleeding in extra
air it reduced the portion of the draft that is applied to the primary (gas
evolving) section.

 

The essential differences between the Davies stove and the Silver are:
secondary air heated outside v.s. inside; packed bed small coal pieces
(about 12mm) v.s. unsized coal (though I recommend <40mm); constricting cone
bringing gases and flames together above the fuel (adapted from the Vesto
coal stove that slightly preceded it, thanks to your visits to both of us):

 

 

 

 

 

 

 

 

 

 

 

 

                                                   Last version of the
stumpy Vesto coal stove, 2003

                                                   The outlet of the
'concentrating disk' as you call it is in the centre

   except that it is a removable cone. John drilled holes in it and has 

   the secondary air blowing down onto the burning coal top which 

   is a good idea.

 

 

 

 

Next difference: regulation by breaking the draft in the chimney with a
controller v.s. controlling the primary air entry into the fuel with a
rotating star-disk.

 

The rest is similar. 

 

Here is a traditional TLUD in South Africa burning coal:

Description: cid:image012.png at 01CD9E9B.5B265250

 

The upper section is only placed there after ignition to provide draft. The
holes are made with a pick axe.

 

This is the description given to a national project in 2004:

 

"Bassa Njengo Magogo Project - The local name for the so-called 'Scotch'
Method of lighting a coal fire by inverting the contents, so that the
volatiles are burned off first, dramatically reduces the time during which a
fire produces smoke and creates a slower-burning fire in a matter of
minutes, and in so doing reduces energy consumption by up to 30% or more
(depending on the user)."

 

http://www.slideshare.net/cenafrica/energy-efficiency-strategy

 

Prof Annegarn (Univ of Johannesburg) remembers, "The "Scotch" method of top
down fire lighting was already current in South Africa in the late seventies
as a way of reducing smoke. Unsuccessfully marketed by the then air
pollution agency."

 

(Quoting from a document) "Rediscovered in the late nineties by the Nono
Institute, a faith based group doing poverty relieve in eastern highveld
(town of Leandre) where they attribute the "discovery" to Granny Mashinini
(sp?), who is used as the poster child/granny for marketing purposes."

 

Hence the name (Gogo means Granny).

 

Further, he says, "There was a smokeless stove developed and marketed - A
modified Dover stove, with a baffle plate that forced the air downward
through the stove and then up again behind the baffle."

 

I am trying to nail down the year it was marketed. Dover is a well-known
cast iron stove making company.

Some of the above is repeats from earlier conversations. The TLUD for fires
in cylindrical containers was 'common knowledge' in South Africa more than
30 years ago and having the tag 'scotch method' probably indicates it dates
back into the 19th century at least. I am sure more evidence will emerge if
we look for it.

 

How far back will we look for TLUD charcoal making technologies?

 

".type of charcoal making system used for centuries in the western part of
Maharashtra State, India used what we now call TLUD (Top Lit UpDraft)
technology."  How about that?

 

<http://www.google.co.za/url?sa=t
<http://www.google.co.za/url?sa=t&rct=j&q=charcoal%20making%20centuries%20we
stern%20part%20maharashtra%20state%2C%20india&source=web&cd=1&cad=rja&sqi=2&
ved=0CB8QFjAA&url=http%3A%2F%2Fwww.garyjones.org%2Fmt%2Farchives%2F001502.ht
ml&ei=cn1nUK_SLcaHhQegxYG4BA&usg=AFQjCNEI0LxVVUA6YQxgfX30Iu3wbZvaWA>
&rct=j&q=charcoal%20making%20centuries%20western%20part%20maharashtra%20stat
e%2C%20india&source=web&cd=1&cad=rja&sqi=2&ved=0CB8QFjAA&url=http%3A%2F%2Fww
w.garyjones.org%2Fmt%2Farchives%2F001502.html&ei=cn1nUK_SLcaHhQegxYG4BA&usg=
AFQjCNEI0LxVVUA6YQxgfX30Iu3wbZvaWA>

 

Regards

Crispin

 

 

Crispin,

 

No.   It is not agreed.   YOU need to provide info that discusses the 

issue, not just telling us to go contact somebody and then use phrases like
"...in use (as I understand it) in the UK for a long time before 

that..."       To say "(as I understand it)" is not very convincing.

 

I would be happy to accept that COAL units the might have been 

substantially larger (I do not know) could have been lit at the top.    

Just present evidence.    We are not here to spend our time to prove you 

are wrong.  You need to prove that you are correct.   You can contact 

the Turkey folks and request sufficiently technical drawings and
descriptions.  We await the results of your investigations.

 

   But as far as I KNOW, John Davies in South Africa was the first to
utilize the Reed-style IDD (Inverted DownDraft that became TLUD in

2004-05) gasification with COAL.

 

Paul

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