Waste Oil Forge?

[2Tim215]

Sorry, the gas in the pic is actually the oil inlet. Testing the forge I used about a l ltr of oil for 2-3 hrs burning. Oil is veg diluted with diesel 60% oil and 40 % diesel.

[MattBower]

OK, a few observations.

First, it looks like your internal dimensions are roughly 6"x6"x15", or 540 cubic inches. Let's round down to 500 for the one "corner" of the interior that's cut off. That's a pretty decent sized forge. Diesel fuel contains in the ballpark of 140,000 BTUs per gallon, or about 36,800 BTU/L. Waste veggie oil contains a bit less. So if you're burning a liter in 2-3 hours, you're probably putting in something less than 12,000-18,000 BTU/hr. Ron Reil says you want about 450 BTUs (per hour) per cubic inch of forge volume to hit welding heat in a presumably well-insulated forge. In a forge of your size that'd be 225,000 BTUs per hour. That seems excessive to me, but the point is that you are not burning nearly enough oil right now. That's why your forge isn't getting hot. You should aim for a gallon per hour to start experimenting, and adjust from there.

Second, I notice that your blower is choked way down to a tiny pipe at one point, presumably because that's the size valve you had on hand, or could easily get. That's no good. That's probably why a big flame is smoky: even with the valve wide open, you're probably not pushing enough air into the forge. You still haven't said what sort of blower you have, but even a blower that's designed to deal with high back pressures (most aren't) is likely to struggle with that arrangement. Get rid of that valve and open up the tuyere so it's at least 1.5" pipe from the blower all the way to the forge. You have to let that sucker breathe -- and you're going to need the extra air in order to burn enough oil to get the BTUs you need. You'll have to find another way to control the air flow.

I'm a little confused about how your forge is set up. Which side are you accessing your work from? Is it the long side, or the "door" at the opposite end from the burner?

Finally, out of curiosity, how are you atomizing your oil? I realize you're using compressed air, but how does the air atomize the oil? What does your spray nozzle look like?

[oof]

i agree with matt. not enough fuel and too much constriction on your blower. i haven't done any serious checks on my fuel usage(waste motor oil), but i think it's about a gallon an hour depending on the psi( i usually run between 5 and 10 on a syphon nozzle)
i also would really like to see your nozzle setup. some oil burners require a pretty good preheat to start working right
mark

[Glenn]

So we can compare Btu to Btu.


Electricity:
1 KW = 3,413 Btu/hr

Natural gas:
1 Cubic Foot of Natural Gas = 1034 Btu’s
1 CCF = 100 Cu Ft = 1 Therm = 103,400 Btu’s
1 MCF = 1,000 Cu Ft = 10 Therms = 1,034,000 Btu’s = 1.034 MMBtu’s

Propane:
1 Gal Propane = 91,600 Btu’s
1 Cu Ft Propane = 2,500 Btu’s

Gasoline:
1 Gal Gasoline (mid grade) = 125,000 Btu’s

Ethanol:
1 Gal Ethanol = 76,000 Btu’s

Fuel Oil:
1 Gal of #2 Fuel Oil = 139,000 Btu’s
1 Gal of #4 Fuel Oil = 145,000 Btu’s
1 Gal of #6 Fuel Oil = 150,000 Btu’s

1 Barrel of Oil = 42 Gallons
1 Btu = 252 calories
1 Btu= .293 watt
1 ton of refrigeration = 12,000 Btu/hr
1lb residential garbage = 2,500 Btu

1lb coal = 12,000 Btu to 15,000 Btu

1lb wood = 3,400 Btu to 4000 Btu

1hp = 746 watts
1hp = 33, 479 Btu/hr (boiler)
1hp = 33,000 foot-lbs./min
1hp = 42,440 Btu/min.

1 watt = 3.412 Btu
1 kilowatt = 1,000 watts
1 kilowatt = 1.341 horsepower
1000 kilowatts = 1 Megawatt

[2Tim215]

Thanks guys for the input, makes a bit more sense now. I did have a 2" gate valve and pipe for the air flow but changed it - will change it all back to 2". The forge is designed so that I can close off from any side and use it for odd shaped art work and sculptures thus changing the dimensions to suit my needs. The fuel and air nozzle is based on the babbington design with oil dripping down on the nozzle and compressed air vaporizing the oil. The air has a .8 mm hole and the oil has a 1mm hole. I can light her up with out having to preheat with gas with the air regulated at 3 PSI.
I think my problem is that I was trying to get the flame to run like a gas burner. Today I will change it all back to the 2" ftgs and see what happens.
The blower is a centrifugal paddle fan that pushes out about 250 cfm.

Will let you all know tonight how it all works out.

[2Tim215]

Some more pics with it burning

[2Tim215]

After 10 minutes still not up to heat. I can't have the air open to full or it blows the flame out even if I add more fuel. There is a point where I have to stop adding fuel or it floods this is where the flame burns nicely with the right amt of air. The compressed air vaporizing the oil is always at around 3PSI - so maybe it takes longer than gas to get up to heat. With gas on the same burner I have it up to heat in around 5-10 minuets.

[MattBower]

Well, yeah, as I said before, you need to burn at least a gallon of oil an hour. I can see from your flame that you're nowhere even close to that. Just opening up the air, alone, isn't going to help you. You also have to deliver enough fuel to the forge. And you're not.

I hate to say this, but I don't know of anyone who has successfully used a Babington design for a serious forge or furnace. They seem really clever in theory, but in practice they're very finicky. I suspect the reason you're having trouble with the flame blowing out is that you have your atomizer ball in the air stream, so at a certain point the blower air is bound to interfere with the drip. Also, I saw some calculations that someone had done a while back, and the amount of oil that you'd have to flow across that tiny hole in order to vaporize a gallon or more an hour just isn't realistic.

Did you consider one of the cruder oil burners (such as the "Brute" or "Moya" designs) that rely on gas to preheat the forge, and drip oil directly into the blower air stream just before it enters the forge? They are indeed crude, but they work.

Another option would be to buy a siphon nozzle to replace the Babington ball. Like this guy:

[2Tim215]

Have changed the burner slightly now for a less complicated venturi system and with good results. Same oil/air inlet system though.



After 10-15 minutes at red heat which is what I want for forging



The setup



The new burner setup

It seems to work better now, though the forge is rather large and could do with possibly a larger burner or more. Will possibly consider a siphon burner if I can get an atomizer here in SA.

Thanks for the input

[2Tim215]

Thanks Matt for that Vid - had the one showing the burner working but not this one. My second burner is based on his one but now that I see he uses a siphon nozzle will have to put some money together and order it from the states - with the exchange rate that will have to wait a while. Appreciate the help.

[oof]

the syphon nozzles i have came from junk torpedo heaters. i'm not sure if you have anything like that there, but it's something to keep an eye out for.
everything i know about burners i learned here
http://www.alloyaven...om/vb/forum.php
if you look through the burner engineering section there are several guys making their own syphon nozzles from scratch.
hope that helps
mark

[2Tim215]

Thanks Mark - gonna have a good look at it now.

[BigCotton89]

Howdy folk! This is my first day with an account but iforgeiron has long been one of my main resources for information. I am posting on this thread because I need help. I want to build a small waste oil forge for some basic bladesmithing. Now I'm no expert on the workings of oil forges as I just discovered them last night; but I threw together a quick design on google sketch-up to see what everyone's opinion is. Now remember this is only a very rough draft of the Idea but it atleast gets the general idea of what I want to build out there. Anyway, this would be a gravity fed waste oil forge. the inside of the forge it'self will be lined with durablanket or something of the likes and that is a small firebrick at the bottom. I would be using a blower as my propulsion system obviously. None of this is to scale or far from perfect. I just want to know if the general idea would work and any suggestions are more than welcome. Thanks in advance y'all!

[MattBower]

Yeah, it'll work -- with a couple caveats. First, you'll need to preheat the forge to a nice orange with something that burns much more easily than oil; propane is a very common choice. You can just inject it right into the tuyere and make a blown burner. Once the forge is hot you can turn on the oil and shut off the propane. (If you want to be able to ignite oil without preheating the forge, it needs to be extremely finely atomized or heated to the point of vaporization. Either of those requires a burner much more complex than what you propose.) Second, in my experience gravity-fed oil is hard to meter consistently. You're forever adjusting the fuel valve.

I suggest you pop over to AlloyAvenue.com and check out the Burner Engineering forum. That's the highest concentration of oil burner devotees that I know of.

[BigCotton89]

thanks for the suggestion matt. i'll be sure to check that out. if anyone has any suggestions on how i can do that id appretiate it.

[MattBower]

Sure. Hope it's helpful.

if anyone has any suggestions on how i can do that id appretiate it.

How you can do what, exactly?

[BigCotton89]

Well as you said I need to get the oil atomized to the point that it is combustible. Now here is my major problem and it might be asking a little much but if I can possibly avoid it I would like to keep from using propane or an air-compressor. I saw the video that you posted earlier in the thread and it seems like a great setup but I want something that uses nothing but waste oil and a blower. http://www.backyardmetalcasting.com/oilburners09.html the "brute" shown here is somewhat along the lines of what I had in mind and that might be what I end up building. I just wanted a slightly refined design to it. Also, with this idea what size blower do I need. I might be going for 120-134 cfm but is that not enough or overkill.

[MattBower]

The Brute requires a preheat.

You will not get atomization with just a blower, using any design I have seen. That'd be the Holy Grail of oil burners. Hasn't happened yet. If you want easy atomization, get a used household oil furnace burner. Depending where you live, it may be free. Otherwise, look into the evaporator burners at AlloyAvenue.

That blower is probably more than enough.

[BigCotton89]

Man Matt! you're just full of ideas aren't you? every time I check this thread you've given me another great idea. When I finally get this forge built most of the credit will go to you.

[MattBower]

Glad to help. Oil burners interest me. I've been reading about them -- and following attempts to build a good, reliable, simple, cheap waste oil burner for foundry use (which should also work fine for a forge, of course) -- for several years now. I built a Brute style burner five or six years ago. I wasn't very satisfied with it, but I did learn that it's possible to produce genuinely scary amounts of heat by burning oil. Someday I'm going to make some crucible steel, and that can get very expensive if you're burning propane. When that day comes, I expect I'll use an oil burner based on a siphon nozzle like the Hago referenced further back in this thread, or a homemade version of it -- unless, in the meantime, someone comes up with an oil burner that's cheaper/simpler and just as effective.

[BigCotton89]

Ok this may seem like a really stupid idea but it's worth putting out there. To "atomize" the oil to some extent is difficult without compressed air but what if you were to use a gravity fed system through one of the mesh lined atomizer nozzles and in the oil tank do kind of a piston pump idea with a liquid tight plunger that you can force the oil pressure to build up and exit the nozzle with more force. My other idea was to mount a small motor on the top and put a dremel wire wheel bit down in the pipe with the oil feeding onto it so it would break up the flow. It wouldn't be as fine as with compressed air but it would be a bit finer than a solid streak and a blower at the back like "the brute".

[MattBower]

Say you have an oil tank with a diameter of about 12" (an old propane or freon tank). The surface of the oil will be 113 square inches. Atomizer nozzles are designed to work on something like 100 psi. To pressurize your oil to 100 psi you'll need to supply 100*113 = 11,300 pounds of force to your piston, a tank that can handle it, and seals on your piston that can handle it as well. Not to mention a precise piston/cylinder fit, that sort of thing. If you reduce the surface area you need less force, but your fuel tank starts to get funny dimensions -- really tall and skinny. Some folks here might know how to build what you want to build. To me, it sounds hard.

Mechanical atomization has been tried a number of different ways. None I've seen have worked very well, but that's not to say you can't come up with something. Other possibilities people have considered to pressurize oil for atomization have included scrap auto parts -- power steering pumps, fuel injector pumps, that sort of thing. Again, all discussed ad nauseum at the other site.

[BigCotton89]

I didn't think of the amount of force it would take. I saw a video somewhere on youtube where the person who built was running the fuel line a 3-7.5 psi and he said that that was enough to atomize the oil and then he had a blower hooked up to the back. with that in mind I would need a max. of roughly 850lbs of pressure. While that still might be difficult to do it's much more achievable.

[MattBower]

Are you sure he wasn't using a siphon nozzle? 3-7.5 psi of air pressure to run a siphon nozzle sounds about right. But you need a compressor for that.

[Jeddly]

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