Steven D. Lee on wed 20 nov 02
Is there anyone out there that knows how to test a burner to see what
its actual BTU output is at a particular pressure. I know that there
are tables with line pressure and orifice size out there that give
the approximate output but I would like to know in more concrete
terms.
What is the least that I can expect at a particular pressure.
What is the efficiency of my burner in burning propane @ a certain
ambient temperature.
Or is what I am asking something that would just be too difficult or
expensive to get figures?
*******************************************************
Steven D. Lee
SD Pottery - The Little Texas Pottery
http://www.sdpottery.com
millenial_age@yahoo.com
14341 FM 112
Thrall, TX 76578
512-898-5195
*******************************************************
Craig Martell on wed 20 nov 02
Hi Steven:
I might be able to help you if you can send some info on the burners. I'm
dealing with this stuff right now and looking at burners for my salt kiln.
What type of burner are you talking about? Who is the manufacturer? What
is the inside diameter of the flame tube? What is the total area in cubic
ft that you are heating and how many burners are you using? What orifice
size are you using and what pressure are you applying?
I can give you btu values for propane up to 25psi. But it's difficult to
say what the burners will do unless someone on the list has used them or
knows something about output. I've used several types of venturis and some
forced air burners and they all have their own individual quirks as you
probably know already. The thing about venturis is that you can size the
orifice to whatever output you might want but if the burner can't entrain
enough air to mix that amount of gas, you actually lose heat and stuff your
kiln full of carbon. You can sometimes use three orifices per burner and
create more turbulence in the mix tube and draw more primary air but how
much more air is unknown. Anyway, I'd be glad to help if I can and I'm
sure there are others on the list who can provide info too. Before I
forget, the 3 orifice/burner is info given to me by Nils Lou.
One thing you can do visually is apply your max pressure to the burners
with your air shutters adjusted for the max amount of primary air and then
look at the flame. If you are seeing yellow and, or, orange instead of
translucent blue, you aren't getting enough primary air. Cut the gas until
you get blue flame and record the pressure, use an orifice-pressure chart
to figure that btus at that setting and you will be close to the max output
of said burner. From what I've seen, burners have an optimum range of
orifice sizes for proper function. For instance, if you drill too large an
orifice in a burner that functions best with hi pressure it's ability to
entrain air will be reduced and it won't work well. Some venturis, such as
Eclipse, don't work well above 11in water colum pressure and they don't
fire well with propane unless you get the flame tube extension that changes
the burner to a "compound injector". On and on it all goes!!
regards, Craig Martell, Hopewell, Oregon
Dave Finkelnburg on wed 20 nov 02
Steven,
Yes, it is expensive to physically measure the BTU output of a burner.
Measuring the amount of gas used is much easier.
The question you ask, it appears to me, is are the tables for gas
pressure, orifice size, and BTU output really accurate? The answer is
absolutely! Of course, the tables assume adequate combustion air. In
reduction you intentionally do not have that, so the tables are only
accurate for oxidizing conditions.
The ambient temperature, and the humidity, do not have a major effect
on burner efficiency. It is measurable, just not significant. Good
question, though!
Good firing,
Dave Finkelnburg, fidgeting again while the kiln
SLOOOOOOOOOOOOOOWLY cools in Idaho :-)
----- Original Message -----
From: "Steven D. Lee"
> Is there anyone out there that knows how to test a burner to see what
> its actual BTU output is at a particular pressure. I know that there
> are tables with line pressure and orifice size out there that give
> the approximate output but I would like to know in more concrete
> terms.
>
> What is the least that I can expect at a particular pressure.
>
> What is the efficiency of my burner in burning propane @ a certain
> ambient temperature.
>
> Or is what I am asking something that would just be too difficult or
> expensive to get figures?
vince pitelka on wed 20 nov 02
> Is there anyone out there that knows how to test a burner to see what
> its actual BTU output is at a particular pressure. I know that there
> are tables with line pressure and orifice size out there that give
> the approximate output but I would like to know in more concrete
> terms.
> What is the least that I can expect at a particular pressure.
Stephen -
You have given us absolutely no information to go on here. How big are your
burners? What are the exact dimensions? Do they have a brand name and/or
model number? What size is the orifice? If you can provide this
information, we might be able to give you some idea of possible BTU output.
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://iweb.tntech.edu/wpitelka/
Pottersmiths' on fri 22 nov 02
If it is natural gas - methane - delivered and metered to your building - a
simple clocking of the meter - a count of the cubic feet of gas will give
you a close measure of energy input as there is basically 1000 btu's per cu
ft at normal residential / light commercial pressures in the US. The measure
would be the number of cubic feet per minute *1000 * 60 = btu/hr - Any gas
utility will have a tech in the Commercial / industrial account department
that would provide the adjustment for your local pressure as well as energy
content of the fuel. Some states require this to be stated on your billing.
I do not fire a gas kiln, I fire an electric. I do know something of
combustion systems and process in industrial applications. Gas kiln
operation is a vastly different activity as you will seek and value the
effect of poor combustion IE: Carbon Trapping, Reduction Atmospheres ......
so forth
You can go a step further than clocking the meter, but this may really go to
gross inaccuracy if done firing with ware in the kiln as the chemistry of
the atmosphere may alter all values - but as I always say in my "Day Job"
"Close enough for Government Work".
The next steps would be a combustion analysis: a measure of the O2 and CO2
in the flue gas without any ware in your kiln. An additional measure of CO
in the flue gas would validate the initial data.
These measurements used to be cumbersome in the past -extracting a sample of
gas and injecting it into a reactant / regent that would change volume
proportional to the exposure to O2, CO2 or CO
Today, All HVAC contractors have electronic digital analysis tools that
would permit this in just a few seconds time. An additional measure would
be the net temperature increase of the combustion products at the barometric
damper or if a pressurized combustion system a small tap may be drilled to
insert sensors for measurement. Most of these analyzers will express the
combustion efficiency.
Phil & Kate Smith
White Bear Lake MN
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Steven D. Lee
Sent: Wednesday, November 20, 2002 7:43 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Testing of Burners for BTU output
Is there anyone out there that knows how to test a burner to see what
its actual BTU output is at a particular pressure. I know that there
are tables with line pressure and orifice size out there that give
the approximate output but I would like to know in more concrete
terms.
What is the least that I can expect at a particular pressure.
What is the efficiency of my burner in burning propane @ a certain
ambient temperature.
Or is what I am asking something that would just be too difficult or
expensive to get figures?
*******************************************************
Steven D. Lee
SD Pottery - The Little Texas Pottery
http://www.sdpottery.com
millenial_age@yahoo.com
14341 FM 112
Thrall, TX 76578
512-898-5195
*******************************************************
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