chuck schultz on wed 31 may 00
greetings, i'm having trouble firing my custom built
natural gas fired downdraft kiln. trying to fire to
cone ten, and only reaches temperature of seventeen
hundred degrees. kiln specs: 32 cubic feet. 4'6"long x
2' wide x 4' high @ arch. dome 10" thick with blanket
inbetween two layers of hard firebrick set on edge.
walls, l4" thick, hard fire brick. arch, 45" wide,
rise of 7 1/4". fired with six venturi burners rated @
75,00 btu's each. burners are verticle. burners sit
level with bottom of kiln, 1" space around burners.
chimney opening at top is 9" x 9", chimney is 8' high.
flue opening inside of kiln is 5" x 9", there is no
damper. natural gas supply: 80' of l" pipe with 2#
pressure, with all six burners open maintains 12 1/2"
water column. gas cocks at each burner. reducing
regulator at kiln. elevation of kiln is 4200' above
sea level. i would appreciate any help/advice,
thank-you, chuck schultz.
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ferenc jakab on thu 1 jun 00
----- Original Message -----
From: "chuck schultz"
To:
Sent: Thursday, 1 June 2000 11:50 am
Subject: requesting help with natural gas fired kiln
> greetings, i'm having trouble firing my custom built
> natural gas fired downdraft kiln. trying to fire to
> cone ten, and only reaches temperature of seventeen
> hundred degrees. kiln specs: 32 cubic feet. 4'6"long x
> 2' wide x 4' high @ arch. dome 10" thick with blanket
> inbetween two layers of hard firebrick set on edge.
> walls, l4" thick, hard fire brick. arch, 45" wide,
> rise of 7 1/4". fired with six venturi burners rated @
> 75,00 btu's each. burners are verticle. burners sit
> level with bottom of kiln, 1" space around burners.
> chimney opening at top is 9" x 9", chimney is 8' high.
> flue opening inside of kiln is 5" x 9", there is no
> damper. natural gas supply: 80' of l" pipe with 2#
> pressure, with all six burners open maintains 12 1/2"
> water column. gas cocks at each burner. reducing
> regulator at kiln. elevation of kiln is 4200' above
> sea level. i would appreciate any help/advice,
> thank-you, chuck schultz.
>
Chuck I think the lack of damper might be the problem, too much draught!
Your burners also sound a little under size but I am not expert on BTUs. We
use Joules here. My 96 cu foot draws 1.8 Gigajoules at peak draw.
Feri.
Marcia Selsor on thu 1 jun 00
According to my estimates you need 960,000 btu's for a 32 cubic foot
kiln (30,000/cu.ft for a hard brick kiln). You have 6 burners rated at
75,000 which gives you 450,000. I have always used these numbers from
Paul Soldner's kiln book from the 60s. They worked for me.
How come no damper?
Marcia Selsor
chuck schultz wrote:
>
> greetings, i'm having trouble firing my custom built
> natural gas fired downdraft kiln. trying to fire to
> cone ten, and only reaches temperature of seventeen
> hundred degrees. kiln specs: 32 cubic feet. 4'6"long x
> 2' wide x 4' high @ arch. dome 10" thick with blanket
> inbetween two layers of hard firebrick set on edge.
> walls, l4" thick, hard fire brick. arch, 45" wide,
> rise of 7 1/4". fired with six venturi burners rated @
> 75,00 btu's each. burners are verticle. burners sit
> level with bottom of kiln, 1" space around burners.
> chimney opening at top is 9" x 9", chimney is 8' high.
> flue opening inside of kiln is 5" x 9", there is no
> damper. natural gas supply: 80' of l" pipe with 2#
> pressure, with all six burners open maintains 12 1/2"
> water column. gas cocks at each burner. reducing
> regulator at kiln. elevation of kiln is 4200' above
> sea level. i would appreciate any help/advice,
> thank-you, chuck schultz.
>
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--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/spain99.html
http://www.silverhawk.com/ex99/selsor/welcome.html
WHC228@AOL.COM on thu 1 jun 00
Chuck
Check to see if you have the correct size orifices in your burner. They may
be sized for propane instead of natural gas. Propane orifices are
substantially smaller than those for natural gas.
The manufacturer of the burners will have the specs.
Bill
WardBurner@AOL.COM on thu 1 jun 00
In a message dated 6/1/00 8:39:29 AM, feri@NETCON.NET.AU writes:
<< > greetings, i'm having trouble firing my custom built
> natural gas fired downdraft kiln. trying to fire to
> cone ten, and only reaches temperature of seventeen
> hundred degrees. kiln specs: 32 cubic feet. 4'6"long x
> 2' wide x 4' high @ arch. dome 10" thick with blanket
> inbetween two layers of hard firebrick set on edge.
> walls, l4" thick, hard fire brick. arch, 45" wide,
> rise of 7 1/4". fired with six venturi burners rated @
> 75,00 btu's each. burners are verticle. burners sit
> level with bottom of kiln, 1" space around burners.
> chimney opening at top is 9" x 9", chimney is 8' high.
> flue opening inside of kiln is 5" x 9", there is no
> damper. natural gas supply: 80' of l" pipe with 2#
> pressure, with all six burners open maintains 12 1/2"
> water column. gas cocks at each burner. reducing
> regulator at kiln. elevation of kiln is 4200' above
> sea level. i would appreciate any help/advice,
> thank-you, chuck schultz.
> >>
Chuck,
You failed to mention what type of burner/orifice you have. I'll assume you
are using MR750's that are rated at 75,000 BTU's. What most companies that
sell these burners don't understand is that a #28 Natural gas orifice that
comes from GACO is for natural gas at 7"wc pressure. That's 1/8 the pressure
you're putting through them. Plenty of gas, but you may be "flooding the car"
and it won't run. There is far more info I'd need from you to be able to
accurately help you. Feel free to call.
Marc Ward
Ward Burner Systems
PO Box 1086
Dandridge, TN 37725
865.397-2914 Voice
865.397-1253 Fax
wardburner@aol.com Email
wardburner.com Online Catalog
Dave Murphy on thu 1 jun 00
Dear Chuck:
I read your post and as I had help with my firings too I thought I would
lend a hand where I could. What jumps out at me (and I am no expert) is
the lack of a damper, the height of your chimney and also the burners might
be under sized btu-wise. Feri helped me out and now my 5th firing was
awsome. I have a new construction as well with the expert design and work
done by one of our good potter's, Rob Tetu (featured in the May issue of
CM). I was using too much fuel. I hardly open the damper to start and
never have burners turned up full. My kiln is at least double the size of
yours but I think you might need a overall btu rating of about 300,000 to
350,000 btus. The elevation might make all this wrong. The Olsen "Kiln
Book" is a great place to get pertinent infornation on all of these
parameters. Good luck!
Barbara Murphy
Waterloo County Pottery
Waterloo, Ontario
Canada
----- Original Message -----
From: chuck schultz
To:
Sent: Wednesday, May 31, 2000 9:50 PM
Subject: requesting help with natural gas fired kiln
> greetings, i'm having trouble firing my custom built
> natural gas fired downdraft kiln. trying to fire to
> cone ten, and only reaches temperature of seventeen
> hundred degrees. kiln specs: 32 cubic feet. 4'6"long x
> 2' wide x 4' high @ arch. dome 10" thick with blanket
> inbetween two layers of hard firebrick set on edge.
> walls, l4" thick, hard fire brick. arch, 45" wide,
> rise of 7 1/4". fired with six venturi burners rated @
> 75,00 btu's each. burners are verticle. burners sit
> level with bottom of kiln, 1" space around burners.
> chimney opening at top is 9" x 9", chimney is 8' high.
> flue opening inside of kiln is 5" x 9", there is no
> damper. natural gas supply: 80' of l" pipe with 2#
> pressure, with all six burners open maintains 12 1/2"
> water column. gas cocks at each burner. reducing
> regulator at kiln. elevation of kiln is 4200' above
> sea level. i would appreciate any help/advice,
> thank-you, chuck schultz.
>
> __________________________________________________
> Do You Yahoo!?
> Send instant messages & get email alerts with Yahoo! Messenger.
> http://im.yahoo.com/
>
>
____________________________________________________________________________
__
> 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.
>
WHC228@AOL.COM on thu 1 jun 00
Chuck
Another problem you may be having is the "no damper" problem. If you are
sucking in too much secondary air through and around your burners you are
having to heat that as well as the kiln. As an example Automobile engines
rely on the incoming air to do a great percentage of the cooling.
The hard brick is also a lot harder to get hot than soft brick or fiber. I
have not done the calculations for you burners to see if you have enough BTUs
to fire the kiln. How dense was your load? you may not have enough firepower.
I'm still suspicious about the size of your orifices
Bill
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