Tom Buck on sun 20 jun 04
Ivor: Lee: ???
this question of producing hydrogen from water has been debated on
Clayart before....see the archives.
in a fossil-fueled kiln especially a wood-fired kiln there always
will be residual incandescent carbon particles present at high
temperatures. these in turn will bring about the "water-gas" reaction
yielding CO and H2 ...these gases will then turn copper green to copper
red and other reduced glaze effects.
the Chinese have long used water in this way...see papers by
Dr Pam Vandiver (pronounced van de veer).
so far, researchers have been unable to the convert water into
Hydrogen and Oxygen at any temperature below 5000 oC, in any method that
yields a surplus of energy... like nuclear fusion at present, cracking
water takes far more energy than that recovered when the hydrogen is
later burned. the secret catalyst to do this remains elusive.
If we hope to get to the "Hydrogen Economy" one path seems
possible, namely, solar power satellites in synchronous orbit sending
energy to the ground for conversion to electricity and it in turn sypplies
an electrolysis facility making hydrogen. The hurdle? $100 billion per
one gigawatt SPS, space trucks to get the panels in orbit, and much more
efficient electrovoltaic cells (this latter is in prospect now).
Perhaps some totally unexpected discovery will lead us to a method
of energy production that is both low-cost and pollution-free.
later peace Tom.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
Ivor and Olive Lewis on mon 21 jun 04
Dear Tom Buck,
You and I know the score on this business of water in the kiln. We are
familiar with the Water Gas Reaction with free carbon at elevated
temperatures. But the canard about water decomposing to give free
oxygen and hydrogen in a potters kiln is frequently repeated popular
ceramic literature written for the ceramic artist. It is also one of
the main planks in salt glaze chemistry.
Thanks for your support.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
Paul Taylor on thu 24 jun 04
Dear Tom
I will try to get hold of this paper
but I doubt if the Chinese put water in their kilns to do any thing but
control the cooling of the kiln.
All other theories I have herd are contradicted by my experience of making
celadons.
--
Regards from Paul Taylor
'Craftmanship is art'
http://www.anu.ie/westportpottery
phone 098 21239
Paul Taylor
Westport pottery
Liscarney
Westport
County Mayo
Ireland
> From: Tom Buck
> Reply-To: Clayart
> Date: Sun, 20 Jun 2004 13:28:43 -0400
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: cracking water
>
> Ivor: Lee: ???
> this question of producing hydrogen from water has been debated on
> Clayart before....see the archives.
>
> in a fossil-fueled kiln especially a wood-fired kiln there always
> will be residual incandescent carbon particles present at high
> temperatures. these in turn will bring about the "water-gas" reaction
> yielding CO and H2 ...these gases will then turn copper green to copper
> red and other reduced glaze effects.
>
> the Chinese have long used water in this way...see papers by
> Dr Pam Vandiver (pronounced van de veer).
>
> so far, researchers have been unable to the convert water into
> Hydrogen and Oxygen at any temperature below 5000 oC, in any method that
> yields a surplus of energy... like nuclear fusion at present, cracking
> water takes far more energy than that recovered when the hydrogen is
> later burned. the secret catalyst to do this remains elusive.
>
> If we hope to get to the "Hydrogen Economy" one path seems
> possible, namely, solar power satellites in synchronous orbit sending
> energy to the ground for conversion to electricity and it in turn sypplies
> an electrolysis facility making hydrogen. The hurdle? $100 billion per
> one gigawatt SPS, space trucks to get the panels in orbit, and much more
> efficient electrovoltaic cells (this latter is in prospect now).
>
> Perhaps some totally unexpected discovery will lead us to a method
> of energy production that is both low-cost and pollution-free.
>
> later peace Tom.
>
> Tom Buck ) -- primary address.
> "alias" or secondary address.
> tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
> mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Paul Taylor on thu 24 jun 04
Dear Ivor
I'm a little confused by this discussion . I always thought that the
sodium in a salt gaze kiln was part of a loose bond with super heated steam.
The bond between the hydrogen and oxygen in the water could only be
separated by extremely high temperatures and at a point where there was no
gain in energy, but the sodium would separate if it had something to adhere
to.
if that was not so we could all heat our kilns to 1260c and quiet
happily keep them at that temperature with water. We could also use a water
injected high temperature boiler to heat the house.
I always supposed that the salt glaze was a distillation of the sodium by
the clay . sodium combined with the clay to flux its surface where as the
super heated steam had no reaction, or very little, with the surface of the
pot.
I have always wondered if the super heated steam did have some reaction
with the clay. The action of oxidation from the oxygen in the water coupled
with the reducing effects of hydrogen gave the oranges and reds from some
clays.
but that I suppose that does not explain the warm colours of some salt
glazed porcelains -- but then I supposed it to be the iron in the steam
coloured the ware. This contradicts the notion that the water does not break
down into its atoms. --- but maybe enough atoms from some of the water do
break down, in the way that water does contain free oxygen and other atoms
which could effect the atmosphere and/or give colour.
But in terms of a complete breaking down of the bonds between hydrogen
ad oxygen you would need a lot more heat and or a lot more time plus a
catalyst for its elements to bond to.
I also supposed that the orange peel effect, came from a highly viscous
soda/clay glaze crawling, but at the same time the gaps formed by the
crawling being instantly filled in by more soda vapour to form a complete
glaze.
Too much can be made of supposition and common sense. For example the
main argument against the world spinning was that we would all be spun off
by centrifugal force. SO Is there any definitive research on what actually
happens in a salt kiln.
-----------------------------
I have also searched in the archive for discussions on water in the kiln and
I find the suppositions as to why the Chinese put water put in the kiln, a
little wanting as well.
Its twice repeated when any body suggests opening up the discussion again
that "its all in the archives" but "I think she (they) doth protest too
much"
--
Regards from Paul Taylor
'Craftmanship is art'
http://www.anu.ie/westportpottery
phone 098 21239
Paul Taylor
Westport pottery
Liscarney
Westport
County Mayo
Ireland
> From: Ivor and Olive Lewis
> Reply-To: Clayart
> Date: Mon, 21 Jun 2004 15:57:00 +0930
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: cracking water
>
> Dear Tom Buck,
> You and I know the score on this business of water in the kiln. We are
> familiar with the Water Gas Reaction with free carbon at elevated
> temperatures. But the canard about water decomposing to give free
> oxygen and hydrogen in a potters kiln is frequently repeated popular
> ceramic literature written for the ceramic artist. It is also one of
> the main planks in salt glaze chemistry.
> Thanks for your support.
> Best regards,
> Ivor Lewis.
> Redhill,
> S. Australia.
>
Lee Love on fri 25 jun 04
Tom Buck wrote:
Thank you Tom. I didn't see this post originally. I think I was
having fun with visitors at the time!
> the Chinese have long used water in this way...see papers by
>Dr Pam Vandiver (pronounced van de veer).
>
>
Tom, There is an article on the use of water in anagama kilns in
Ceramics Technical #17 (it is right next to the article by Euan Craig
that has photos of my kiln I took while I was building it.) The
article is from the authors MFA thesis and is being published in
installments.
Many of the traditional uses were incidental. Modern
wood firers are tying to figure out how to make use of what was done by
accident in the past, I think.
> so far, researchers have been unable to the convert water into
>Hydrogen and Oxygen at any temperature below 5000 oC, in any method that
>yields a surplus of energy... like nuclear fusion at present, cracking
>water takes far more energy than that recovered when the hydrogen is
>later burned. the secret catalyst to do this remains elusive.
>
>
This is good for potters actually. Ivor more or less
gafawed at the notion of hydrogen and oxygen being separated saying it
would blow the kiln apart or something. Unlike folks trying to "crack
water" to produce H2 for fuel, we are just trying to effect the
atmosphere of the kiln. So, temporary "re-arrangement" of the
molecule is enough to change the atmosphere. No need to actually
permanently split them. There is too much stuff in the wood kiln
atmosphere to hope for that.
I achieved some good results in my first trails.
First thing I noticed was a jump in temperature, especially when
spraying water in the firebox after stoking. I am guessing that what
happens, is that usually the temp drops when you first stoke, because
you are putting in much more fuel than there is oxygen to burn it. It
is like when a carburetor is set too rich. I don't know for sure, but
the water may slow the burning down and keep the fuel from choking out.
The other thing I notice is that the kiln was evened out
by the introduction of water. Steam carries the heat energy around
the kiln efficiently.
The third effect was that I got more color inside the
footring. I think the pressure of the steam forced the kiln
atmosphere into the enclosed space.
> If we hope to get to the "Hydrogen Economy" one path seems
>possible, namely, solar power satellites in synchronous orbit sending
>energy to the ground for conversion to electricity and it in turn sypplies
>an electrolysis facility making hydrogen. The hurdle? $100 billion per
>one gigawatt SPS, space trucks to get the panels in orbit, and much more
>efficient electrovoltaic cells (this latter is in prospect now).
>
>
We live in exciting times! Maybe energy
created from fusion can help too.
> Perhaps some totally unexpected discovery will lead us to a method
>of energy production that is both low-cost and pollution-free.
>
>
>
Maybe our next step in kilns is hydrogen fuel? Or
fuel cells to power electric kilns. Or.... a combination of both.
--
Lee in Mashiko, Japan http://mashiko.org
http://journals.fotki.com/togeika/Mashiko/ Commentary On Pottery
| |
|
