Cindy Strnad on sun 4 feb 01
Erik,
If you want to build your own gas kiln, I highly recommend a copy of Nils
Lou's "Art of Firing". There's also "The Kiln Book" by Olsen (sp?), a
classic which I wasn't really able to follow, but that doesn't mean you
won't understand it. Talk to Steven Branfman at sbranfpots@aol.com --he can
set you up with these books and recommend others you might like.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Tom Buck on sun 4 feb 01
The Btu is "British thermal unit" which is a unit of heat used in the
Imperial system, and it is the heat required to raise one pound of water
one degree Fahrenheit when the water is at its maximum density, ie, at
39.1 degree F.
In Systeme International ("metric") the same amount of heat would
be described by 1055 joules, or 1.055 kJ.
good conversions. Peace. Tom B.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
Erik Buitenhuis on sun 4 feb 01
Hallo everybody,
I'm looking into building a natural gas heated kiln. There is a lot of
information in the archives, but a BTU doesn't mean anything to me. What is
it the abbreviation of and does anyone know the conversion factor to kW
?(which is 3.6 MJ/hour)
Also, does anyone know a good reason not to build a gas oven like a typical
wood heated oven, like this:
...*.*
...*.*
...*.*
...*.*********
...*.*.......*
...*.......*.*
...*********.*
->..........*
...***********
? It strikes me as a simpler design than a downdraft oven with the flue
between and below the burner ports.
Thanks in advance,
Erik Buitenhuis.
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dayton j grant on mon 5 feb 01
BTU's are british thermal units ,i dont know any conversion tables but im
sure they have been standardized and are available somewhere ,and on the
subject of oven or kiln construction ,i didnt make the rules that heat
follows ,but it does follow them without fail , and to make an oven you
should study heat with someone who has more experience than you do at
this point and soon the rules of heat transfer will become clear to you
and you will be able to make heat based machines to your own specific
needs whether they be pottery or casting or distillation or whatever
.....for starters this is the" golden triangle"HEAT is flat at the bottom
of the triangle and is a direct result of molecular friction ,FUEL is at
the left summit of the triangle and is always a vaporised prior to
ignition (when you burn wood and you look up close the wood is not really
burning it is the liquid oils that come out when the wood is heated and
the oils are vaporised and this is what burns ) so all solid fuel goes
through three stages before it can ignite the stages are solid ,liquid
and vapor..liquid fuel is one step closer and gas is ready to ignite
immidiately ...and on the right side of the summit of the triangle is
oxygen i dont know that much about oxygen ,i think you would need a vacum
chamber to fully study the full effects of oxygen on heat but i think it
is generally assumed that oxygen is necessary for flame which is the main
element of a non-electric non-solar oven or kiln (im not really sure
about any of this im just passin on stories that i heard )
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Erik Buitenhuis on tue 6 feb 01
Hi Dayton,
Thanks for the effort of trying to explain fire to me, but I know more about
thermodynamics than I need to build a kiln. My question was directed at the
practical side of it, which stone do I put where, and especially, why do
people use certain setups that to me look like a waste of space?
>fuel is always vaporised prior to ignition
This is not true. Pure carbon for one doesn't evaporate until it is
extremely hot, and liquid carbon doesn't even exist, but it can burn anyway.
Oxygen has free electrons that "attack" the atoms in the fuel molecules,
which then rearrange (the electrons) to give different molecules, in the
case of hydrocarbon fuels (natural gas, wood) water and carbon dioxide.
Heat is not the friction of molecules rasping against each other, but simply
molecules moving (the faster they move the hotter). Molecules are almost
completely elastic, like billiart balls, and if they collide there is no
friction; the movement of the one is transferred to the other.
There's a lot of talk about Nils Lou's book, and somebody gave the title,
which is useful.
Have a nice day,
Erik Buitenhuis.
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ferenc jakab on tue 6 feb 01
Each British thermal unit = (1.055 056 E3) joules
or 1000000 joules is equivalent to: 948.6 btu
or 1 kilowatts is equivalent to: 56.92 btu«IT» per minute
copied from... Conversion Buddy. available at http://ntr.net/~jpresley/
dayton j grant on wed 7 feb 01
hi Erik
yeah i guess there are some dicrepencies in what i said ,i was led to
beleive that proir to ignition, of even gunpowder, there is a change from
solid ,that a solid could not ignite, but this is just the talk of laymen
over beer ,and i guess that 'molecular acceleration' would be a better
description than 'molecular friction',for the cause of heat ,and heat
transfer is due to faster moving molecules coming in contact with slower
moving molecules and causing them to, in turn be accelerated ,so then i
guess molecular acceleration is transferred my molecular contact (like
billiard balls) and oxygen becomes catalytic with certain forms of fuel
at certain different (rates of acceleration) tempratures?
you dont have to answer me, i know that i dont know what im talking about
except im comparing inforation from different people ,but now that we
know that you know about heat you must figure out the most efficient
configuration of 'stones ' or whatever you are using for insulation or
containment you must consider the characteristics and properties of the
materials that you will use to produce the heat and to transfer the heat
and to accumulate the amount of heat that you will need to affect your
chosen materials in the desired way ,or you could use a plan out of a
book ...
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