ROT: Drilling / Cutting Butane Tanks

"AJH" <[email protected]> wrote in message
news:[email protected]...
> On Wed, 03 May 2006 23:50:33 +0100, Steve Taylor
> <[email protected]> wrote:
>
>>Seen some incredibly efficient woodburning cooking stove plans too -
>>using small PC fans to force convect the fires
>
> It's a bit of a hobby with me, small stoves. Forced draught makes a
> load of difference to combustion performance. A researcher at Phillips
> has produced a stove with a fan powered from a cheapish thermoelectric
> generator, the aim is to mass produce them cheaply for those 2 billion
> people that still cook using wood stoves.
>
> AJH
>

TVS who pops in here once in a Blue moon converted an Oil Burning Boiler and
added a exhaust and Turbo which in turn pumped air in to the combustion
chamber. The Uni wouldn't let him run it on site... when they did run it I
seem to recall it glowed quite well from Tobys account... and the water got
warm PDQ too.

Lee

On Thu, 4 May 2006 20:05:33 +0100, "Lee_D"
<[email protected]> scribbled the following
nonsense:

>"AJH" <[email protected]> wrote in message
>news:[email protected]...
>> On Wed, 03 May 2006 23:50:33 +0100, Steve Taylor
>> <[email protected]> wrote:
>>
>>>Seen some incredibly efficient woodburning cooking stove plans too -
>>>using small PC fans to force convect the fires
>>
>> It's a bit of a hobby with me, small stoves. Forced draught makes a
>> load of difference to combustion performance. A researcher at Phillips
>> has produced a stove with a fan powered from a cheapish thermoelectric
>> generator, the aim is to mass produce them cheaply for those 2 billion
>> people that still cook using wood stoves.
>>
>> AJH
>>
>
>TVS who pops in here once in a Blue moon converted an Oil Burning Boiler and
>added a exhaust and Turbo which in turn pumped air in to the combustion
>chamber. The Uni wouldn't let him run it on site... when they did run it I
>seem to recall it glowed quite well from Tobys account... and the water got
>warm PDQ too.
>
>Lee
>

I have an old turbo kicking around, and I have just been offered
serious money for the one I've just built my my Head of Dept, who also
teaches DT......
--

Simon Isaacs

"Bad officials are elected by good citizens who do not vote"
George Jean Nathan (1882-1955)

AJH wrote:

> It's a bit of a hobby with me, small stoves. Forced draught makes a
> load of difference to combustion performance. A researcher at Phillips
> has produced a stove with a fan powered from a cheapish thermoelectric
> generator, the aim is to mass produce them cheaply for those 2 billion
> people that still cook using wood stoves.

Does a propane tank lend itself to a small, efficient HEATER, rather
than a cook stove though ? I've part made my contribution to the Afl
October cook-off, but these inverted downdraught stoves have really
intrigued me too, and I could modify what I have here....

Steve

On Thu, 04 May 2006 21:18:31 +0100, Steve Taylor
<[email protected]> wrote:

>Does a propane tank lend itself to a small, efficient HEATER, rather
>than a cook stove though ? I've part made my contribution to the Afl
>October cook-off, but these inverted downdraught stoves have really
>intrigued me too, and I could modify what I have here....

I think the IDD term is being phased out in favour of toplit
updraught. These TLUD devices really need a narrow cross section and
quite dry fuel but a 6" stove pipe makes quite a good patio heater run
this way. In theory they are so clean burning you can use them just
like an un flued paraffin or propane stove, in practice I wouldn't.
The thing is at the end of the burn they are simply CO generators,
during the initial burn if the flame goes out the thick acrid smoke is
a good warning at the end of the burn you might just wake up pink as a
lobster and rather *stiff*.


AJH

On Thu, 4 May 2006 20:05:33 +0100, "Lee_D"
<[email protected]> wrote:

>TVS who pops in here once in a Blue moon converted an Oil Burning Boiler and
>added a exhaust and Turbo which in turn pumped air in to the combustion
>chamber. The Uni wouldn't let him run it on site... when they did run it I
>seem to recall it glowed quite well from Tobys account... and the water got
>warm PDQ too.

We did that and actually netted some power from it. Trouble is that at
700C steel's strength is a tiny fraction of what it is at ambient and
45psi exerts quite a force over the pressure pot. So casting a ceramic
liner for the pressure vessel took some design and a lot of cost.

Ours occupied a good part of the floor of Cardiff's engineering dept,
it got so embroiled in funding and grant bodies I never got to play
with it. I still have the original MAN turbo and oil pumps in my
garage and the spare lucas APUs are floating around on a farm in
Worcester.

At the same time a researcher at the university was working on pulse
combustors, they sounded just like a machine gun being fired.

AJH

TLUD ? Must remember that - its a much more obvious way of puting it !

How long is your 6" tube ? My son and I made a tiny camping stove last
week, but the ratio of diameter to length seemed wrong to me, too
narrow, too tall so bugger all out, very quickly.

Can you blow a column of wood chippings or even sawdust in one ? I saw
one guy burning rice hulls in an elegant indonesian design I think it
was,

If you made a gasifer, and then lit the gas, so flames were played over
a radiant, like a gas fire, would that be much less efficient than a
length of stove pipe ?

Steve

On Thu, 04 May 2006 19:50:50 +0100, AJH <[email protected]> wrote:

>A researcher at Phillips
>has produced a stove with a fan powered from a cheapish thermoelectric
>generator, the aim is to mass produce them cheaply for those 2 billion
>people that still cook using wood stoves.

Woodburning stoves for cooking has become a serious environmental
issue in some areas. The research (I think) which your are talking
about was a mad cloggie who started by doing something very similar to
the cutting up a gas bottle strategy. ISTR he achieved the same
results using a third of the fuel or somesuch.

There was a huge alternative living expo a few years ago which looked
at low-tech solutions - one was based on a very high efficiency burner
- which also had a feed to boil water for safe(er) drinking. Other
rather neat, equally low-cost low-tech gadgets included a condensation
water collector (big sheet of plastic over a hole type stuff).

A lot of the 'survivalist' techniques originally came from 'grass
roots', have been modified and are now going back home as it were.
The best and most officient means I've found for heat and coffee (erm,
boiling water) has to be my well battered Kelly kettle.


--
"We have gone from a world of concentrated knowledge and wisdom to one
of distributed ignorance. And we know and understand less while being
increasingly capable." Prof. Peter Cochrane, formerly of BT Labs
In memory of Brian {Hamilton Kelly} who logged off 15th September 2005

On 4 May 2006 15:38:41 -0700, "[email protected]"
<[email protected]> wrote:

>How long is your 6" tube ?

I've done it several times at about 4 ft. There's one chap
experimenting with an inclined tube model.

http://www.sylva.icuklive.co.uk/temp/tlud.jpg

is a picture I just uploaded of a 6" ventilation pipe stuffed with
dried heather clippings. The galv burned off ages ago but there is a
hazard as it does. You can see the pyrolysis offgas rising from the
tube and igniting as a diffuse lazy flame.

If you look at the bottom of the tube on the right you will see white
crayon marks, I used these to show the downward progress of the
pyrolysis front.

> My son and I made a tiny camping stove last
>week, but the ratio of diameter to length seemed wrong to me, too
>narrow, too tall so bugger all out, very quickly.

Many of the experimenters used old food cans, the term tincanium was
coined for this resource. My first ones were natural draught and 6"
diameter, I think they held about 500g of dried woodchip. Of course
woodchip is not very dense and a much longer burn can be had with wood
pellets
>
>Can you blow a column of wood chippings or even sawdust in one ? I saw
>one guy burning rice hulls in an elegant indonesian design I think it
>was,

Yes but fan pressure becomes an issue with deep beds, there are work
arounds. Are you familiar with the "boy scout's candle"? A tlud
version of these with multiple holes can be made.
>
>If you made a gasifer, and then lit the gas, so flames were played over
>a radiant, like a gas fire, would that be much less efficient than a
>length of stove pipe ?

I think it would be more efficient because you would be rejecting heat
directly into the room, just like a propane fire, but just as with a
propane fire there are problems like condensation and CO. Flue pipes
get the gases out of the room but at the cost of losing some heat.
Unlike gas boilers wood burners don't do well run in a condensing
mode.

AJH

AJH wrote:
> On 4 May 2006 15:38:41 -0700, "[email protected]"
> <[email protected]> wrote:
>
>> How long is your 6" tube ?
>
> I've done it several times at about 4 ft. There's one chap
> experimenting with an inclined tube model.
>

Soon weld a tube like that up. Just a grill at the bottom ?

> http://www.sylva.icuklive.co.uk/temp/tlud.jpg
>
> is a picture I just uploaded of a 6" ventilation pipe stuffed with
> dried heather clippings. The galv burned off ages ago but there is a
> hazard as it does. You can see the pyrolysis offgas rising from the
> tube and igniting as a diffuse lazy flame.

Kicks out a warming amount of heat for what ? an hour or so ?
>
> diameter, I think they held about 500g of dried woodchip. Of course
> woodchip is not very dense and a much longer burn can be had with wood
> pellets
Where do you get pellets from ?

>> Can you blow a column of wood chippings or even sawdust in one ? I saw
>> one guy burning rice hulls in an elegant indonesian design I think it
>> was,
>
> Yes but fan pressure becomes an issue with deep beds, there are work
> arounds. Are you familiar with the "boy scout's candle"? A tlud
> version of these with multiple holes can be made.

No, thats a new term for Googling. I didn't know you could burn the
little buggers for heating purposes....

Thanks for the tips.

Steve

On Fri, 05 May 2006 22:59:48 +0100, Steve Taylor
<[email protected]> wrote:

>Soon weld a tube like that up. Just a grill at the bottom ?

There's no real need for a grill at the bottom unless you intend to
burn out the char in bottom lit updraught mode, in which case you will
up the temperature everything has to withstand from the 600C of the
tlud to >1100C (steel burns out quickly above 700C)
>
>> http://www.sylva.icuklive.co.uk/temp/tlud.jpg
>>
>> is a picture I just uploaded of a 6" ventilation pipe stuffed with
>> dried heather clippings. The galv burned off ages ago but there is a
>> hazard as it does. You can see the pyrolysis offgas rising from the
>> tube and igniting as a diffuse lazy flame.
>
>Kicks out a warming amount of heat for what ? an hour or so ?

This depends entirely on the amount of primary air you let in and the
mass of material yo stuff in the tube. Basically you "liberate" about
2.5kWhrs of heat and produce some char for every 1kg of dry wood.

With the lazy flame I showed most of the heat is lost in convection
and you only benefit slightly from the radiant heat from the tube
above the pyrolysis front and flame. You'd need to add a "bluff body"
of some sort to get heated up and radiate this down. At the same time
premixing the secondary air will stabilise the flame.

>Where do you get pellets from ?

I service a pellet boiler that has been installed in a solar thermal
system who's control system has needed a lot of snagging. Each time
something goes wrong I have to clean out the boiler. As the silo hatch
is 3 floors up I give them the opportunity of carrying the pellets I
empty out of the boiler back up or I offer to dispose of them ;-).

There are half a dozen places making them, 3 major ones (Bridgend,
Chester and Durham) and the firm I sub to imports them from France and
Latvia.

>No, thats a new term for Googling. I didn't know you could burn the
>little buggers for heating purposes....

Wow two non PC thoughts in one sentence!

It's simply a tin can, pierced at the bottom, with a wooden dowel
stood vertically in the middle. The section around this packed and
pounded with dry sawdust. Then withdraw the dowel and light the top.

These tlud things are very sensitive to moisture. Above 25% and they
simply refuse to burn because the heat feedback to the fuel below is
low compared with a conventional updraught fire. The interesting thing
is that at the moisture content rises from 0-25% the char decreases
from 25% of the dry mass to zero.

The other main criteria is that bits of burning debris should not be
able to fall to the bottom of the fuel bed, else it simply turns into
an updraught fire. I just started a simple one using some wood from a
broken softwood wardrobe, pictures posted at

www.sylva.icuklive.co.uk/temp/tlud.html

one for Martyn (cork stuck so for demo purposes only), and this is
exactly what happed as I had not packed it well enough. You can see
how rudimentary primary air control can be. Also note the secondary
air path.

AJH

AJH wrote:

>> No, thats a new term for Googling. I didn't know you could burn the
>> little buggers for heating purposes....
>
> Wow two non PC thoughts in one sentence!

Oi Fank you.

>
> It's simply a tin can, pierced at the bottom, with a wooden dowel
> stood vertically in the middle. The section around this packed and
> pounded with dry sawdust. Then withdraw the dowel and light the top.

Ah, I see.

Steve