Michael Wendt on sat 16 feb 08
I have a thought about how we can actually
measure the effect of the thickness on the
thermal efficiency of an electric kiln.
I have a standard electrical meter I can install
in the circuit to the test kiln to record the
actual KWH used.
I will build a single element 120 volt test kiln
with 4.5 " thick walls.
I will use my Cole-Parmer recording digital
pyrometer to log the temperature inside during
different firing cycles versus the outside skin
temperature. I will use the computer control
to control the firing rate with a standard dead
mass representing a load.
After a full run at different rates, I will reduce the
wall thickness overall to 2.5" and repeat the
same firings. An actual comparison will then
be possible because we will know:
actual power consumption
actual skin temperature
actual firing time to cone
I believe the results should be scalable
because the computer control will keep
the firing profile in line as long as the
wattage per square foot is high enough
to keep up with the firing profile of the
controller.
Probably, I will test at least to cone 6
although it makes sense to build the
unit with cone 10 capabilities just in case
we want to check that data range as well.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
Joseph Herbert on sat 16 feb 08
Lee wrote: We have to keep the wastes in isolation for spans of time we
can't actually understand and spans that no know civilization has survived.
(the half life of some radioactive wastes is 100,000 years.)
The production of electricity in the amounts demanded by modern living,
which includes running 14,000 watt appliances, comes with two interesting
waste disposal questions attached. One is related to nuclear waste (the
sexy one); the other to carbon dioxide (not so sexy).
Nuclear -
Actually the half lives of fission products range from milliseconds to
millions of years. Uranium 238, a major constituent of spent fuel, has a
half life of 4.5 billion years. It should be noted that the more radiation
a given amount of material emits per unit time, the shorter its half life.
The more reactions, the sooner it changes to something else. One should
also note that many of the decay reactions produce other radioactive
daughter products with their own characteristic half lives.
One of the quantities assigned to a radioactive isotope is a Curie. A curie
is the mass of the isotope necessary to produce a stated number of decay
reactions per second. The number of reactions is rather large, 3.7 x 10^10
(37,000,000,000) per second. A curie of radium 226 is about a gram; a curie
of Uranium 238 is over half a ton. The half life of radium 226 is 1600
years; the half life of U 238 is 4.5 billion years (near the age of the
earth). The long half life and low rate of decay of U 238 allowed it to be
an article of commerce before WWII because of the low perceived danger of
the material.
There is no long term repository for commercial nuclear waste currently
available. The Yucca mountain project what was intended to take commercial
spent fuel is under construction and political attach. Almost all the
nuclear fuel that has ever been at a nuclear power plant in the United
States is still there. A few plants have been closed and the spent fuel
moved to other temporary storage. Some closed plants are still in limbo
with the spent fuel pools intact waiting for a repository. Dry cask storage
is a possibility that a few plants use but the material is still on the
plant site. There is no where else for it to go.
Fossil -
For every ton of carbon burned in a fossil power plant, three tons of carbon
dioxide are released into the air that we all share. Coal, gas, and oil
fired plants are all the same, a ton of carbon is a ton of carbon. The
waste disposal method is the same for each, into the air, our air.
Waste issues -
100 nuclear reactors produce about 15% of the electricity in the United
States. Each unit produces about 65 tons of spent fuel (waste) every 18
months. every three years that is 1300 tons of nasty stuff to be stored and
guarded.
Coal fired plants burned 1529 tons of coal in 2006 and released 4590 tons of
Carbon Dioxide into the atmosphere. 550,000,000,000 cubic feet of natural
gas was burned to make electricity in 2006 and those plants released 3 times
as much carbon dioxide into the air.
So you have about 400 tons of nasty old nuclear waste per year sitting in
spent fuel pools, or you have all those tons of CO2 in your air that you are
breathing right now. Pick you poison.
Joe
Joseph Herbert
Technical Writer
Irving, Texas
214-725-8305 (Cell)
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.20.6/1282 - Release Date: 2/15/2008
7:08 PM
John Rodgers on sat 16 feb 08
Joe,
I'm an old biologist at heart, trained in it, with lots of physics and
chemistry to boot. - not current on it, but still remember the
principles. It appears to me the statistical curve of population growth,
the curve of energy demand, and the curve of pollutions, both CO2
increase and toxins increase, are simply going to collide in one big
explosion and there will be a collapse of life and civilization on the
planet. I have believed this since I was an undergrad. I still do. I
always likened living on the planet earth to be much like a colony of
bacteria living on media in a Petri dish. In time, all the resources
will be gone, the food consumed, and the place overrun with bacterial
colonies to the point that bacteria produced toxins will poison the
environment in the Petri dish which in turn will poison the bacteria
which will kill them all off.. Some populations intentionally decrease
in number to protect their environment and therefore themselves, others
do not - they just don't care. So, the inevitable result is catastrophe.
I am also an old hunter among other things. I have seen things happen in
nature, and we , being part of nature, are not immune, no matter what we
might think. I have over the years seen populations ebb and flow, rise
and fall, all according to the whims of the environment in which
creatures live. If we as a planet population do not change our ways, and
slow down our self destruction of our only home, we will die as a
civilization, as a population, and eventually as a species, and there
will be a lot of human misery and agony in the process.
Regards,
John Rodgers
Chelsea, AL
Joseph Herbert wrote:
> Lee wrote: We have to keep the wastes in isolation for spans of time we
> can't actually understand and spans that no know civilization has survived.
> (the half life of some radioactive wastes is 100,000 years.)
>
> The production of electricity in the amounts demanded by modern living,
> which includes running 14,000 watt appliances, comes with two interesting
> waste disposal questions attached. One is related to nuclear waste (the
> sexy one); the other to carbon dioxide (not so sexy).
>
> Nuclear -
> Actually the half lives of fission products range from milliseconds to
> millions of years. Uranium 238, a major constituent of spent fuel, has a
> half life of 4.5 billion years. It should be noted that the more radiation
> a given amount of material emits per unit time, the shorter its half life.
> The more reactions, the sooner it changes to something else. One should
> also note that many of the decay reactions produce other radioactive
> daughter products with their own characteristic half lives.
>
> One of the quantities assigned to a radioactive isotope is a Curie. A curie
> is the mass of the isotope necessary to produce a stated number of decay
> reactions per second. The number of reactions is rather large, 3.7 x 10^10
> (37,000,000,000) per second. A curie of radium 226 is about a gram; a curie
> of Uranium 238 is over half a ton. The half life of radium 226 is 1600
> years; the half life of U 238 is 4.5 billion years (near the age of the
> earth). The long half life and low rate of decay of U 238 allowed it to be
> an article of commerce before WWII because of the low perceived danger of
> the material.
>
> There is no long term repository for commercial nuclear waste currently
> available. The Yucca mountain project what was intended to take commercial
> spent fuel is under construction and political attach. Almost all the
> nuclear fuel that has ever been at a nuclear power plant in the United
> States is still there. A few plants have been closed and the spent fuel
> moved to other temporary storage. Some closed plants are still in limbo
> with the spent fuel pools intact waiting for a repository. Dry cask storage
> is a possibility that a few plants use but the material is still on the
> plant site. There is no where else for it to go.
>
> Fossil -
>
> For every ton of carbon burned in a fossil power plant, three tons of carbon
> dioxide are released into the air that we all share. Coal, gas, and oil
> fired plants are all the same, a ton of carbon is a ton of carbon. The
> waste disposal method is the same for each, into the air, our air.
>
> Waste issues -
>
> 100 nuclear reactors produce about 15% of the electricity in the United
> States. Each unit produces about 65 tons of spent fuel (waste) every 18
> months. every three years that is 1300 tons of nasty stuff to be stored and
> guarded.
>
> Coal fired plants burned 1529 tons of coal in 2006 and released 4590 tons of
> Carbon Dioxide into the atmosphere. 550,000,000,000 cubic feet of natural
> gas was burned to make electricity in 2006 and those plants released 3 times
> as much carbon dioxide into the air.
>
> So you have about 400 tons of nasty old nuclear waste per year sitting in
> spent fuel pools, or you have all those tons of CO2 in your air that you are
> breathing right now. Pick you poison.
>
>
> Joe
>
> Joseph Herbert
> Technical Writer
> Irving, Texas
> 214-725-8305 (Cell)
>
>
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.5.516 / Virus Database: 269.20.6/1282 - Release Date: 2/15/2008
> 7:08 PM
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
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>
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>
>
>
Larry Kruzan on sun 17 feb 08
Hi Bill,
If I read that chart correctly a 18" with 2 1/2" uses about 1/2 kW more than
a kiln with 3" walls. Yet the price for that extra 1/2" of wall is
$70-$100. My electric cost is 12 cents per kW, so 6 cents per firing.
$100/.06=1666.66 firings to break even. Since I fire each of my electric
kilns twice a week on average - I would break even in 32 years. Hummmmmm I
am 53 years old...............
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of William & Susan
Schran User
Sent: Sunday, February 17, 2008 9:19 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: [CLAYART] Clay mythology - electric kilns vs. gas and wood
On 2/16/08 11:25 PM, "Michael Wendt" wrote:
> An actual comparison will then
> be possible because we will know:
> actual power consumption
> actual skin temperature
> actual firing time to cone
L&L kilns has published a comparison of 2 1/2" vs 3" brick top loading kilns
of various sizes, providing information on BTU loss and storage:
http://www.hotkilns.com/brickstudy.pdf
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
____________________________________________________________________________
__
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, change your
subscription settings or unsubscribe/leave the list here:
http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com
William & Susan Schran User on sun 17 feb 08
On 2/16/08 11:25 PM, "Michael Wendt" wrote:
> An actual comparison will then
> be possible because we will know:
> actual power consumption
> actual skin temperature
> actual firing time to cone
L&L kilns has published a comparison of 2 1/2" vs 3" brick top loading kilns
of various sizes, providing information on BTU loss and storage:
http://www.hotkilns.com/brickstudy.pdf
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Robert on sun 17 feb 08
I've been considering this as well. It seems as a group we could
easily amass the relevant data.
On the fuel kiln side, we would need firing logs indicating volume of
kiln, insulation thickness, mass of ware, and specific firing
times/rates i.e. 250,000 btu burners (rated at 11" w.c.) 2" w.c. for
2hrs, 3.5" w.c. for 3hrs, 8" w.c. for 6hrs, etc. Even without a gas
meter we could calclate the total btu input of a given firing and a
corresponding btu/lb of ware produced. Cone 6 and cone 10 would be two
different sets. In terms of scalability, we might see a difference
between volumes as well.
On the electric side the kwh, as you described, Michael, could be
converted to btu's and standard transmission loss factors applied to
determine actual fuel consumption per lb ware.
I'm certain we have the data amongst us. Anyone game? I would be
happy to run the numbers if folks sent me the raw data. Off list preferably.
I, for one, would like to have objective data on this. The carbon
police are coming....,
Take care,
Robert
Michael Wendt wrote:
> I have a thought about how we can actually
> measure the effect of the thickness on the
> thermal efficiency of an electric kiln.
> I have a standard electrical meter I can install
> in the circuit to the test kiln to record the
> actual KWH used.
>
>
Hank Murrow on wed 20 feb 08
On Feb 17, 2008, at 9:06 AM, Robert wrote:
> I've been considering this as well. It seems as a group we could
> easily amass the relevant data.
>
> On the fuel kiln side, we would need firing logs indicating
> volume of
> kiln, insulation thickness, mass of ware, and specific firing
> times/rates i.e. 250,000 btu burners (rated at 11" w.c.) 2" w.c. for
> 2hrs, 3.5" w.c. for 3hrs, 8" w.c. for 6hrs, etc. Even without a gas
> meter we could calclate the total btu input of a given firing and a
> corresponding btu/lb of ware produced. Cone 6 and cone 10 would be
> two
> different sets. In terms of scalability, we might see a difference
> between volumes as well.
Dear Robert;
Your suggestion had me getting out the calculator to figure the
natural gas usage for my Doorless Fiberkiln. I had done this once
before during the testing phase in the mid-80s, quoting a figure of
$18 per firing then and $24 now. Well, I went to the Gas Co. for rate
information, and asking again how many cu.ft. of gas is in a therm,
etc. I even read the meter during one firing to corroborate the
figures from my firing logs. I was consuming an average volume of gas
for each firing including the soak in oxidation of around 3300 cu.ft.
At the rate we pay here in Eugene($1.12/1000 cu.ft.) that firing cost
$3.70! I was astonished, and quickly drove over to the Gas Co. to
have them check my logs, and check my billings, etc. Well, all
checked out, and my Doorless Fiberkiln costs less than $4 to fire a
28 hour cycle to cone 11, plus a soak in oxidation for six hours.
Geez, I knew it was good, but not that good.
For the record, it is a 38" (inside measure) cube(31 cuft), lined on
five sides with 6" of High Temperature Ceramic Fiber (compressed to
12#/cuft density), with a 2" lightweight(75#/cuft) castable floor
backed up with 5" of block insulation. The 16 tip burner array is fed
by one orifice of 7/32" size, and maximum pressure at the orifice is
5.5" wc. The flue exit is a five inch opening yielding an exit area
of 19.6 sq. in. The damper closes that to around 13 sq. in. at my
maximum gas setting during a firing.
>
> I'm certain we have the data amongst us. Anyone game? I would be
> happy to run the numbers if folks sent me the raw data. Off list
> preferably.
Let me know if you need more....... and I would really love to know
how much gas other fiberkiln users report.
Cheers, Hank in Eugene
www.murrow.biz/hank
>
> I, for one, would like to have objective data on this. The carbon
> police are coming....
Well, they will likely drive on past my studio, because at 20 firings
a year, I am using $80 for a year's firings. Damn sweet!
Thanks again for asking the question, Robert.
Hank in Eugene
www.murrow.biz/hank
Hank Murrow on thu 21 feb 08
On Feb 20, 2008, at 1:22 PM, Hank Murrow wrote:
>
> On Feb 20, 2008, at 12:35 PM, Robert wrote:
>
>> Hank,
>> For comparative analysis I think we need to know the mass of
>> finished ware produced by the firing. Then we could calculate a
>> btu per mass relationship that would provide an accurate basis
>> for comparing electric to fuel as well as comparative fuel
>> consumption for different final temperatures and kiln volumes.
>> Your total btu consumption is easy to figure from the total volume
>> of gas but I think we should include the bisque firing as well.
>
> A typical load weighs 500.8#s total. 220#s for shelves, 100.8#s for
> posts, and 186#s for wares(retail worth $1760).
> My electric bisque kiln is 3" thick, 8 cuft volume. No idea how
> much to fire. Typically two glaze loads in each bisque.
>
> The weight of the fiber lining is 368#s, the floor refractories
> weigh 300#s. That is it for now.
And Further.....
........It appears that with my Doorless Fiberkiln, to bring 186 Lbs.
of ware($1760.00) and 321 Lbs. of furniture and some fraction of the
668 Lb. refractory lining to Cone 11 over 28 hours and also give it a
six hour soak during cooling may require 4000 Cu.Ft. of natural gas @
$1.12 per 1000 Cu. Ft.(Eugene price). Total for natural gas per
firing = $4.48, or .024 cents per pound of ware, and each pound of my
ware is worth $9.46 retail. So, with my ware pricing, and my kiln,
the ratio between fuel cost and retail worth is 1 to 394 at the
present time.
Figuring stuff like this out is not my favorite thing, but this time
it was rewarding, I almost enjoy this headache.........
Cheers! Hank
www.murrow.biz/hank
Hank Murrow on fri 22 feb 08
On Feb 20, 2008, at 12:20 PM, Hank Murrow wrote:
>
> On Feb 17, 2008, at 9:06 AM, Robert wrote:
>
>> I've been considering this as well. It seems as a group we could
>> easily amass the relevant data.
But first you have to talk to the knowledgeable person at the gas
Company!
A red-faced Hank is now able to report that a Therm = 100 Cu.Ft. of
natural gas, or 100,000 BTU. So Hank's Doorless Fiberkiln uses around
3700 Cu.Ft. or 37 therms, which cost $41.07 in Eugene, for a cost of
22 cents per pound of ware fired to Cone 11 and given a soak in
cooling. Seemed impossible that the kiln would fire for $4....... and
it was impossible. When I first figured the costs for this kiln in
1985, gas cost was $0.48 per therm($18/firing), so with gas now $1.11
per therm, $41 seems reasonable, if not as spectacular as the figure
I reported earlier. With a load of 186 pounds, it works out to cost
22 cents per pound of ware, about what the clay itself costs.
Anyway, learning a lot as I try to get it right.
Cheers, Hank
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