Karl Platt on sat 19 feb 11
A couple points relative to the ongoing discussion.
First, H2 powered cars will *never* come about.... unless we finally figu=
=3D
re out=3D20
a viable fusion reactor, which is entirely possible, but the time horizon=
=3D
is out=3D20
there a long way. Note that H2 is not free in nature and the quantity of=3D=
20=3D
energy necessary to liberate it as such -- a thermodynamic thing ;-)
Heat recovery from a gas fired ceramic kiln is, of course, entirely possi=
=3D
ble and=3D20
over the years a wide array of schemes have been used. Typical arrangemen=
=3D
ts=3D20
use either metal or ceramic recuperators to pre-heat the combustion air u=
=3D
sing=3D20
the flue gas. These can work only if combustion input is controlled on a =
=3D
mass-
flow basis. Absent means to moderate air flow to compensate for the=3D20
expanded volume of heated air combustion will go rich. Placing this contr=
=3D
ol is=3D20
not especially difficult, but for a typical studio scale operation the co=
=3D
st will be=3D20
~$2.5k net provided that the kiln is already fitted with suitable combust=
=3D
ion=3D20
hardware -- preferably nozzle mixing burners designed for the purpose.=3D2=
0=3D
Without proper control and hardware the potential savings will not be rea=
=3D
lized=3D20
and there will be great difficulties with atmosphere control -- tending t=
=3D
oward=3D20
strong reduction as the air temperature increases.....but some people lik=
=3D
e that.
Then one needs to ensure that the recuperator doesn't leak -- ceramic=3D20
recuperators are especially notorious for leaking - they should also be m=
=3D
ade of=3D20
high thermal conductivity material such as SiC. Recuperators on a batch t=
=3D
ype=3D20
process such as a ceramic kiln will fatigue and crack -- with metals usua=
=3D
lly at=3D20
welds, but most often in the hottest sections owing to the thermal expans=
=3D
ion=3D20
of the metal and metallurgical changes occuring at elevated temperatures =
=3D
--=3D20
Yes, there are alloys that resist these things better than others (I am p=
=3D
artial=3D20
to 310 SS), but these also quickly run up costs as they are expensive and=
=3D
=3D20
require careful technique in fabrication. Careful design can help, too, b=
=3D
ut this=3D20
is a longer discussion that doesn't further much in the small scale ceram=
=3D
ic=3D20
world.
In short, I've done the math for these schemes on small ceramic kilns and=
=3D
the=3D20
payback (ROI) is very long -- usually on the order of 5 years + assuming =
=3D
that=3D20
nothing falls apart and the system operates perfectly for its entire life=
=3D
.=3D20
The per/unit cost for each item fired in a common gas kiln is typically v=
=3D
ery=3D20
small -- Let's say <=3D3D $1.00/ item which amounts to 1-3% of selling pric=
=3D
e for=3D20
most items produced -- assuming we're discussing tableware. In any event,=
=3D
=3D20
again, the ROI for complicating combustion is simply not much, and the=3D20=
=3D
payback sucks.
Firing economy is better served by using low mass construction and/or=3D20
insulation and putting in a combustion system capable of precise control =
=3D
when=3D20
the kiln is built. Not only will there be good economy, but beast results=
=3D
will be=3D20
easier to replicate -- I've said this many times before. Paying attention=
=3D
to=3D20
ensuring good convection for early stages of firing and uniform radiation=
=3D
for=3D20
later stages will also support least-cost firing. Heat recovery for perio=
=3D
dic kilns=3D20=3D20
is an economic loser.
Lee on sat 19 feb 11
On Sat, Feb 19, 2011 at 7:20 AM, Karl Platt wrote:
> A couple points relative to the ongoing discussion.
>
> First, H2 powered cars will *never* come about.... unless we finally figu=
=3D
re out
> a viable fusion reactor, which is entirely possible, but the time horizon=
=3D
is out
> there a long way. Note that H2 is not free in nature and the quantity of
> energy necessary to liberate it as such -- a thermodynamic thing ;-)
In Japan, they are using solar powered lasers to turn Magnesium Oxide
back into Magnesium. I believe the energy solutions will not be
what we currently imagine.
http://www.nextenergynews.com/news1/next-energy-news9.19b.html
I was just listening to a program related to the electric
car company in China BYD. (another example of our being left in the
terminological dust.) The speaker was saying that electric car
development must be in parallel with decentralized power generation.
They are working on solar, but the co-generation plants, like what are
now being tested in homes in Japan are another way.
I heard the founder of BYD say, creating a Chinese car based on
the internal combustion engine would be difficult, because everyone
has the jump on them where this old technology is concerned. But
electric cars are much simpler and they are on a level playing field
because nobody has an advantage there.
>
> Heat recovery from a gas fired ceramic kiln is, of course, entirely possi=
=3D
ble and
> over the years a wide array of schemes have been used.
I remember seeing photos of an old English pottery, where a horizontal
run was used from the kiln to the stack as a place to dry pots and dry
blunged clay.
Typical arrangements
> use either metal or ceramic recuperators to pre-heat the combustion air u=
=3D
sing
> the flue gas. These can work only if combustion input is controlled on a =
=3D
mass-
> flow basis. Absent means to moderate air flow to compensate for the
> expanded volume of heated air combustion will go rich. Placing this contr=
=3D
ol is
> not especially difficult, but for a typical studio scale operation the co=
=3D
st will be
> ~$2.5k net provided that the kiln is already fitted with suitable combust=
=3D
ion
> hardware =3DA0-- preferably nozzle mixing burners designed for the purpos=
e.
> Without proper control and hardware the potential savings will not be rea=
=3D
lized
> and there will be great difficulties with atmosphere control -- tending t=
=3D
oward
> strong reduction as the air temperature increases.....but some people lik=
=3D
e that.
>
> Then one needs to ensure that the recuperator doesn't leak -- ceramic
> recuperators are especially notorious for leaking - they should also be m=
=3D
ade of
> high thermal conductivity material such as SiC. Recuperators on a batch t=
=3D
ype
> process such as a ceramic kiln will fatigue and crack -- with metals usua=
=3D
lly at
> welds, but most often in the hottest sections owing to the thermal expans=
=3D
ion
> of the metal and metallurgical changes occuring at elevated temperatures =
=3D
--
> Yes, there are alloys that resist these things better than others (I am p=
=3D
artial
> to 310 SS), but these also quickly run up costs as they are expensive and
> require careful technique in fabrication. Careful design can help, too, b=
=3D
ut this
> is a longer discussion that doesn't further much in the small scale ceram=
=3D
ic
> world.
>
> In short, I've done the math for these schemes on small ceramic kilns and=
=3D
the
> payback (ROI) is very long -- usually on the order of 5 years + assuming =
=3D
that
> nothing falls apart and the system operates perfectly for its entire life=
=3D
.
>
> The per/unit cost for each item fired in a common gas kiln is typically v=
=3D
ery
> small -- Let's say <=3D3D $1.00/ item which amounts to 1-3% of selling pr=
ic=3D
e for
> most items produced -- assuming we're discussing tableware. In any event,
> again, the ROI for complicating combustion is simply not much, and the
> payback sucks.
>
> Firing economy is better served by using low mass construction and/or
> insulation and putting in a combustion system capable of precise control =
=3D
when
> the kiln is built. Not only will there be good economy, but beast results=
=3D
will be
> easier to replicate -- I've said this many times before. Paying attention=
=3D
to
> ensuring good convection for early stages of firing and uniform radiation=
=3D
for
> later stages will also support least-cost firing. Heat recovery for perio=
=3D
dic kilns
> is an economic loser.
>
--=3D20
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Lee on sat 19 feb 11
On Sat, Feb 19, 2011 at 9:57 AM, Lee wrote:
> http://www.nextenergynews.com/news1/next-energy-news9.19b.html
>
> =3DA0 =3DA0 =3DA0 =3DA0 I was just listening to a program =3DA0related to=
the elect=3D
ric
> car company in China BYD. =3DA0(another example of our being left in the
> terminological dust.)
Haha! Spell checker fun. This should read: technological
.
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
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