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Biodiesel Fired Kiln


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#1 cabako

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Posted 04 August 2016 - 12:36 PM

Hi all,

 

I have done some research and found a few write ups and youtube videos of folks firing their kiln with veg oil.  I have an unlimited supply of ASTM quality biodiesel (made from veg oil) at hand and  I'd like to figure out how to build and fire my own kiln with the bio.

 

My goal is to make a small pilot kiln first and then move up to a larger kiln later.  I envision the first small kiln ~ 5-10 cubic ft. to work out of a 5 gallon carboy/jerican of biodiesel.  1 gallon of Biodiesel = ~128,000 BTU.  So my first question is, how do I rough estimate kiln size & cone temp (say cone 10) Vs. BTU required?

 

Second question, how difficult is it to control the temp at such a small kiln size while firing with liquid fuel?

 

I am still working out how to make a air driven venturi style fuel burner, but I assume It would have to be rather small flow rate for 5-10 cu. ft.  Since biodiesel has much lower viscosity than veg oil it would not have to be pre heated in any way. 

 

Anyway just thinking out loud and would love to hear if any input & if members have a liquid oil fired kiln/ burner setup.

 

Thanks,

 



#2 Foxden

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Posted 04 August 2016 - 05:27 PM

I will follow your progress on this as I find it quite interesting. For a number of years I was making my own biodiesel from recycled restaurant oil. At that time I thought about a biodiesel fueled kiln, too. I went so far as to purchase a used Beckett Oil Burner (eBay), used in oil furnaces. I never did hook up the burner to see if it burned the biodiesel as my source for used oil dried up and I quit making the fuel.

I think you will find data regarding these burners and the BTU produced. Based on my readings you would need 10-16,000 BTU per cu ft if your kiln is 9inch thick soft brick. Based on output you could calculate the maximum size kiln you could fire with such a burner. It may take more than one burner.

Keep us posted.

#3 High Bridge Pottery

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Posted 05 August 2016 - 05:08 AM

I think it is anywhere from 6,000-16,000btu per cubic foot depending on how much insulation you have. Will double check when I get home in my kiln book for the estimated figures.

 

Marcia has posted some burner designs and stuff before but from a quick search I can't find anything.


One physical test is worth a thousand expert opinions.

 

gallery_23281_871_611.png gallery_23281_871_239.png gallery_23281_871_701.jpg

 
 


#4 Sputty

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Posted 05 August 2016 - 07:52 AM

As an addendum to cabako's question, has anyone experience of using Babington burners to fire kilns?

Are they controllable enough, or are they just 'on or off' type devices?

 

This sort of thing, apparently fine to use with bio-diesel:

 

How to build a Babington Oil Burner



#5 cabako

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Posted 05 August 2016 - 10:27 AM

FYI All,

 

Here is the video inspiration.  Looks rather simple, but the devil will be the nozzle used, I can't tell what nozzle it is from here.  Ive done some research on "black gold" nozzles, the one in this vid looks almost like a pressure washer nozzle...

 



#6 cabako

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Posted 05 August 2016 - 10:28 AM

Thanks for the input so far, good info!



#7 cabako

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Posted 15 May 2017 - 01:43 PM

I'd just like to update this if anyone is interested.  I have acquired some large used kiln brick, a 100 psi air compressor, and a venturi style nozzle and adapter for the burner portion which is: Delavan 17147 adapter (1/8" fuel inlet, 1/4" air inlet) and a DELAVAN 30609-2 (SNA .20) SIPHON NOZZLE. These were purchased off ebay for about $25 each, shipped.  I think this will be the easiest hassle free burner for a small cu ft. kiln.  I'll put the wool around the brick walls, i don't have that much but at least the brick will give it some thermal mass.  I'll post pics when its all setup.



#8 cabako

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Posted 22 May 2017 - 11:36 AM

Alright here is a video link of the first test fire, for those of you following along.  The delavan nozzle system works well...But it needs to be kept as cool as possible obviously and I will have to remove the pipe and build some sort of firebox out of kiln brick.  I will probably also split the air line to inject some air directly behind the nozzle to keep it cool and get a better burn.  It should be possible to control the temp by reducing the regulator pressure, but it will be interesting to see how/if it can achieve a complete firing, and just how easy that temp control will be...

 

Try not to notice the massive amounts of cardboard near the kiln... :rolleyes:

 



#9 neilestrick

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Posted 24 May 2017 - 10:01 AM

Very good! I would love to see some pics of the burner itself.


Neil Estrick
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Owner, Neil Estrick Gallery, LLC
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#10 cabako

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Posted 24 May 2017 - 02:16 PM

Neil,

I don't have pics of the actual burner, but if you google the two parts : Delavan 17147 and Delavan 30609-2 and you will see images of them.  Just screw the nozzle into the adapter, air goes to the back inlet and fuel to the middle inlet of the adapter body.  The black o-ring could be a definite point of failure if it gets too hot and the nozzle could melt too I guess...It should be designed for high temps...maybe not kiln temps though...I have seen people just crimp down the end of a 1/8" tube or pipe and you will get a good spray, but you still have to make the venturi portion yourself.  

 

A friend has a broken electric kiln shell that I could have, so I think I may get a larger nozzle and put the burner through the bottom peephole.  Should work better than this sad excuse of a kiln...



#11 triolaz

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Posted 26 May 2017 - 01:50 PM

I don't know antthing about this subject but I find it very interesting. I know Sam Clarkson (Santa Cruz, Californina I think) used to fire his kiln with vegetable oil, he may be a valuable resource to you

#12 cabako

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Posted 07 July 2017 - 12:11 PM

Here is a video of 2nd firing, Nozzle can be seen clearly in this one.

 

https://www.youtube....h?v=RkkIJcSrzuE

 

A few observations: the heating seemed to stall around 760-780C.  Typically if heating stopped with my propane burner I would crack the lid slightly and the temp would shoot up again.  That didn't happen in this case, temperature would only decrease.  Even with an extra forced air line at the nozzle/inlet

 

I tried increasing pressure from 5 psi to 10 psi in the hopes of getting more fuel out.  I believe this only increased the air flow.  Larger nozzle size, 0.65 or 1.0 gph may be needed. 

 

The air compressor I am using is very small, cheap and constantly runs.  A larger tank & air production volume is necessary so it won't constantly run & overheat.  This may defeat the point of using this system however.  I will have to calculate the cost of air compressor usage Vs. Electric kiln...

 

Might look into a pre-fab oil burner system...BUT I think at the end of the day the easiest solution is a gravity fed delivery, similar to the 3-tiered veg oil burner system that Sam Clarkson built. (thank you for the reference Triolaz)



#13 Magnolia Mud Research

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Posted 07 July 2017 - 05:23 PM

I recommend that you calculate the air requirement for complete combustion of the oil.  From what I have read so far in the thread, I suspect you are using too much air for the amount of oil being burned, and this will be the limiting factor of the kiln max temperature. 
  
Waste vegetable oil carbon, hydrogen, oxygen content should be readily available from an internet search.  If you are using diesel as prototype fuel the necessary composition data is also available from an online search.   Aim to supply a BTU/hr energy rate to the kiln about twice what you would use in an electric kiln and design your burner to handle that amount of oil flow equivalent.  Once you know the oil flow needed, then work on the air supply for atomizing the oil,  and partitioning the primary and secondary air flows. 
  
A well designed setup will include some flow measuring devices for both oil and air.  Otherwise, you are flying blind in the dark with no GPS.
    
Keep going, you are making progress.  The flame looks good,
    
LT



#14 cabako

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Posted 08 July 2017 - 01:03 PM

Ok good point!  From a government website: Biodiesel has an air fuel ratio of 13.8:1  So then 1kg of Soybean C18 based bio needs 13.8kg of air (23% Oxygen wt.) for total combustion.  1 gallon of bio has a density of about 0.880 g/mL which is about 7.34 lbs/gal.  1 gallon of bio contains about 128,000 BTU/Gal. 

 

Lets assume the worst and use HBP's 16,000 BTU/ft^3 number to fire my 3ft^3 thin fiber kiln to cone 10. 16x3 = 48,000 BTUs or 0.375 gal of bio (this seems really low to me...)

 

0.375 x 7.34 = 2.75 lbs or 1.25Kg of bio...

 

1.25 x 13.8 = 17.25Kg of air.  Density of this air coming out hot of air compressor @ 35C = 1.46 Kg/m3 = 25.185 M^3 or 889.4 Cubic Feet needed.

 

Lets say we want to spread the firing out over 8 hrs = 889.4/480 min = 1.85 CFM total required...

 

When sizing the nozzle it is rated in gallons per hour.  In this case I need 0.375/8 = 0.047 Gph. I am at 0.25 Gph @ 5 psi thru nozzle which is using 0.49 CFM.

 

According to this I am over on fuel and low on air. Since this is a fiber kiln it probably requires much much more BTUs...

 

I didn't have my morning coffee today...anyone want to check my math?






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