EDWIN GOULD on tue 31 mar 98
I'm in need of information concerning the spacing and dimensions of the
place for the two burners on each side. I'm building a down draft, 20
cu ft kiln in my back yard; a first for me and a friend. The venturi
2.5 inch, 150 kbtu/hr burners were used by a previous user at 12 inches
apart. the burner openings are currently 7x8 in. and 9 in.apart. The
floor is 37wx24 deep. Using k26 brick inside and hard brickoutside.
the chimney is 10x13 x 8 feet. and the chimney opening on the floor is
9x10. There will be a bag wall on eitehr side. There will be two
venturi burners on each side. Top is a keystone arch. Can anyone give
me some guidance. edgould@erols.com
Vince Pitelka on wed 1 apr 98
>I'm in need of information concerning the spacing and dimensions of the
>place for the two burners on each side. I'm building a down draft, 20
>cu ft kiln in my back yard; a first for me and a friend. The venturi
>2.5 inch, 150 kbtu/hr burners were used by a previous user at 12 inches
>apart. the burner openings are currently 7x8 in. and 9 in.apart. The
>floor is 37wx24 deep. Using k26 brick inside and hard brickoutside.
>the chimney is 10x13 x 8 feet. and the chimney opening on the floor is
> 9x10. There will be a bag wall on eitehr side. There will be two
>venturi burners on each side. Top is a keystone arch. Can anyone give
>me some guidance. edgould@erols.com
Edwin -
When placing the burners in the side wall, I have always divided the inside
dimension of the side wall into quarters, and placed the center of the front
burner port 1/4 of the way back from the front, and the rear port 1/4 from
the back. You mention that your ports are (or are going to be?) 7" by 8".
Why such huge ports? There is no reason to have ports larger than 4.5" wide
by 5" high. Having larger ports is a mistake, and simply allows unneeded
cold air to be drawn into the kiln, drastically decreasing the efficiency of
your firings. The port need only be large enough to allow adequate
secondary air to enter around the burner tip. Perhaps you are using unusual
brick sizes. If that is the case, and the ports are really that large, I
suggest you make burner port inserts from 2600 degree softbrick, with a
round port bored throught he center. The port should tapers larger towards
the inside of the kiln. The minimum diameter of the port, at the outside
surface, should be 3.5" diameter for a 2.5" burner tip, and the face of the
burner tip should be mounted 1/2" from the outer face of the port insert and
kiln wall.
Good luck -
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Mmpottery on thu 2 apr 98
Don't you need larger ports at high altitude??
Vince Pitelka on fri 3 apr 98
>Don't you need larger ports at high altitude??
This is a good question. I have never lived at high altitudes, and have not
had to face the problem. In my experience, as long as a natural draft kiln
has adequate stack height to develop good convection vacuum, very little
port space is needed around the burner tips - just enough for necessary
secondary air. So, perhaps the issue is stack size and height rather than
burner port size. I'd like to hear an opinion from someone firing up in the
thin cold air. Jonathan?
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Jonathan Kaplan on sat 4 apr 98
>----------------------------Original message----------------------------
>>Don't you need larger ports at high altitude??
>
>This is a good question. I have never lived at high altitudes, and have not
>had to face the problem. In my experience, as long as a natural draft kiln
>has adequate stack height to develop good convection vacuum, very little
>port space is needed around the burner tips - just enough for necessary
>secondary air. So, perhaps the issue is stack size and height rather than
>burner port size. I'd like to hear an opinion from someone firing up in the
>thin cold air. Jonathan?
>- Vince
>
>Vince Pitelka - vpitelka@DeKalb.net
>Home 615/597-5376, work 615/597-6801, fax 615/597-6803
>Appalachian Center for Crafts
>Tennessee Technological University
>1560 Craft Center Drive, Smithville TN 37166
My current kiln is a 50 cubic foot car fiber kiln firing with two forced
air burners and a Honeywell rectified flame system.
The kiln is inside our plant so there are no wind issues to deal with.
There are two burners firing from the rear and the port size is 4.5" x 5"
high with is fairly standard, thus 22.5 square inches times two ports is
45 square inches of exit flue area, which is what I have, actually 42
square inches.
The burner ports are straight on design with no taper, an open port system
The kiln drafts pefectly well into the very early stages of pre-heat. Now I
do have an open stack design where the built kiln stack meets the
Metalbestos triple walled system, going up12 feet through the roof and
another six feet above the roofline.
I used tapered commercial burner blocks on a kiln many years ago that was
out side, had atmostpheric burners and worked wonderfully.
I have designed and am coordinating a kiln building project for Castle Clay
Artists in Denver in June and we are usuign 2 M400 burners from Marc Ward.
Pors will will be as above, and exit flue approximately the same. The kiln
will be outside.
So firing at high altitudes (Steamboat Springs is about 7000 ft) has not
been an issue with me. I would, however, always use a forced air system
for reasons of efficiency and economy, burner turndown, etc.
Jonathan
Jonathan Kaplan, president jonathan@csn.net
http://www.sni.net/ceramicdesign/
Ceramic Design Group Ltd./Production Services
PO Box 775112
Steamboat Springs CO 80477
(USPS deliveries only)
Plant Location
1280 13th Street Unit 13
Steamboat Springs CO 80487
( UPS, courier, and common carrier deliveries)
(970) 879-9139*voice and fax
http://www.sni.net/ceramicdesign/
http://digitalfire.com/education/clay/kaplan1.htm
WardBurner on sat 4 apr 98
Hey folks,
<<<>>>
The general rule of thumb is to increase port and flue sizes an additional 50%
once you get over 5000ft.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
B A HARPER on tue 7 apr 98
Hi -
I assume the increase of 50% of inlet and exit flues over 5000 ft.
also applies to wood kilns. Are there any other modifications to a
wood kiln for over 5000 ft. (like stack height, cross section, etc.)
Here at Flagstaff, we are at about 7000 ft.
Thanks -
Brian Harper
WardBurner on wed 8 apr 98
Yes, it applies to wood kilns and you may want to make your chimney about 10%
higher with the crosssection no smaller than the total exit flues. Also you
might want to taper your chimney so that it's 10% smaller at the top than the
bottom.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
B A HARPER on thu 9 apr 98
Hi Marc -
I'm not sure I understand exactly why you would make the top of the
chimney 10% smaller. How far from the top would you taper it in? Is
it along the lines of a venturi effect?
Thanks -
Brian Harper
WardBurner on fri 10 apr 98
<<<I'm not sure I understand exactly why you would make the top of the
chimney 10% smaller. How far from the top would you taper it in? Is
it along the lines of a venturi effect?
Thanks -
Brian Harper
Brian,>>>>
For the same volume to move through a restriction, it has to speed up. This
helps the draft. Taper the chimney in three equal distance sections at about
3% each time.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
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