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02-01-2008, 02:07 AM #1
Waste Oil Heater, gun type burner
I am in the process of building from scratch a large waste oil burner. It is made from a 4' length piece of 30" sch 40 pipe, with 3/8"plate ends welded on. I have been going back and forth over using either a drip type or gun type feed system. One of the big questions that keeps coming up is how to aim the gun into the furnace. Just aiming it at the back of the unit,or have it aimed at an angle so the flame hits the inner surface and swirls around, or whatever is easiest? One of the nice things about using a nice thick piece of pipe, is I can cut holes wherever I want, and weld in an appropriate implement, and if it doesn't work right, can weld the hole shut and try something else! As far as drip goes, with a long pipe like this, do I need a manifold that drips oil in several places, as well as a "pan" of some sort that is almost as long as the pipe? Lots of questions. I am going to experiment with the thing outdoors first, to get some idea of what works and what doesn't, but any advice would shorten the R&D time!
02-01-2008, 09:32 AM #2
I made one three years ago, and I'm finally happy with it. If somebody tells you they made one that ran perfectly first time you know they are lying.
My stove is 6' of 28" well casing laying horizontally, and has 1/2" plate dividing it into top and bottom sections. Burner is at the door end of the bottom section. Top half is packed with 1 1/2" heat exchanger tubes. Fan at one end blows through the tubes. Exhaust travels 5' along the bottom half, then 5' the other way through top half to get to the chimney. I lined the bottom half with firebrick, but I'm not sure that is strictly necessary.
I did not want any filters to mess with so I used a small hydraulic pump driven by a DC gearmotor/speed controller to pump oil from my supply tank and meter it into the stove. The pump pickup tube just dangles a few inches above the bottom of the tank, and I can drain off water or sludge when necessary.
Oil travels upwards into the stove and sort of bubbles into a short trough. As it drips out of the trough it falls through a jet of compressed air which atomizes it. I used a tiny flat fan spray nozzle and run 25 or 30psi on the regulator. The spray nozzle is aimed downward 30* at a 6" diameter, 1 1/2" thick cast iron disc with a cup shape turned into the top.
I start the stove by putting a cup of diesel fuel into the pan, light it, and immediately start the oil pump and the air. The pan will get over 800 degrees in 10 minutes or so, and then just acts as sort of a hot tube igniter. The combustion is mostly happening in mid air where the air jet hits the oil stream.
It took a few tries to get a burner system that worked-I couldn't make it run evenly until I added the heavy burner pan-That seems to be a key ingredient for several types of home built stoves. I run about 1/2 gallon of oil per hour to heat a well insulated 40' by 80' building. There is no visible smoke after the stove gets hot, and it won't fill a 5 gallon ash bucket in two weeks.
02-01-2008, 09:36 AM #3
02-01-2008, 07:13 PM #4
If I might pick your brain a little bit? The pan you talk about that the oil sits in once you have the pump going. How thick is the material you used, and how deep does the oil get once everything is running smoothly? When this pan is at 800*, does the oil vaporize before it drips off the end? Also, this cast iron disc. Is the dish shape to direct the air stream into a larger pattern, or am I seeing it wrong?
Thanks for the info
02-01-2008, 08:14 PM #5
Dale, like scott says the first one never runs right. Mine is based on a narrow wood stove with a 1/4" drip line in the rear wall that drips onto a 8 x 12" 1/2" steel plate. The plate vaporizes the oil. The trick is to either get the oil or the plate hot before the oil hits the drip plate. I use air in the line to vaporize the oil.
My current setup uses an old fork lift propane tank that I fill with oil and then pressurize. I have two metering valves, one in the oil, and one in the air bubble above. I run them into a T that goes to the stove. The air pressure vaporizes the drip in the line and works pretty well. My only problem has been the oil metering valve gums pretty quick.
You can wrap or run the oil line inside the stove to preheat it, but you have to be carefull that it doesn't get too hot or the oil will carbon up the line and clog it.
I'll start mine with some kindling and then throw a decent sized chunk in after pushing the coals under the plate to preheat it, then turn up the main regulator to 10-15psi and the oil / air vapor will auto ignite. If I keep the door cracked it won't smoke, or I'll turn the air up if I want it to heat up quickly. I've had the walls start to glow. To shut it down I turn the air valve up and slowly lower the regulator pressure to zero.
02-01-2008, 08:16 PM #6
Oh yeah, my first design used a dish, but it got coaked up with carbon.
My goal was to build a clean burner that didn't use a lot of air.
02-01-2008, 10:32 PM #7
Could we see a picture of your burner?........Thank you.......Dean
02-01-2008, 10:39 PM #8
SVS I sure would like more info on your burner. Sounds like a great idea. Thanks in advance.
02-01-2008, 11:21 PM #9
the only drawback of this was to slow the flow rate of the smoke up the chimney ...
so concentrating the smoke ...
and making it look to the neighbours like i was polluting the environment.
there was actually less smoke coming out than a coal fire
they grassed me up .
and I'm longer doing it.
i could probably have got away with it if i lived in the sticks
you can get 10 times the amount of heat out of oil by giving it less air
i had the whole house central heating powered by it ............and it was so efficient that 1.2 litres of old oil an hour could sustain water coming out of a tap at over 60 degree Centigrade indefinitely.
another draw back of heating water ...is that the smoke condenses on the inside of the boiler ........giving it a thick coating of soot ..........horrable soot like printers ink .......that had to be cleaned off ........about a 1/4 inch deep of it ..........every 24 hours.......or you loose efficiency .
i was planning to make a centrafuge ...to get rid of most of the soot making carbon out of the oil.
normal oil burners would heat up the sides till they glowed red ....thus no soot.
All the best....markj
02-02-2008, 12:31 AM #10
I'll try to explain a little more clearly.
The angle iron trough is only there to drop the oil into the air jet.
The air jet is very low volume @ 30psi. My 60 gallon air compressor might cycle every 4 hours if I'm not using air elsewhere in the shop. I've never bothered to do the math to arrive at actual air consumption. The majority of combustion air flows in through a simple butterfly valve. The tighter I can run this valve without smoking the more heat I get. It might not matter, but I am starting to think I should have a damper in the chimney instead or in addition.
My pan started out as a cast iron disc 6" diameter by 2" thick. Any thick chunk of steel or cast iron would work. I put the disc in the lathe and turned a shallow cup into one end. It's purpose is to be a reservior for the diesel fuel used to warm up the stove, and secondarily as hot bulb type ignition system. When the stove gets up to temperature, the disc should be DRY and HOT. If it's wet then the air nozzle is sooted up and not atomizing the oil, or the stove is getting over fueled.
The flame appears 1"-2" after the oil stream hits the air jet and billows out for a 12"-18". Looks like a big blowtorch with bright yellow to nearly white flames. (Orange and red lazy flames are a sign it's running rich.) This "blowtorch" is aimed at the disc and keeps it hot enough to ignite any oil globs that actually reach the disc. I don't know if the combustion is a result of heat+mixture(think Diesel engine) or flames actually propagating "upstream" from the hot plate towards the air/fuel jet. Sort of chicken/egg and I'm no Chem E.
To be absolutely honest, the Cast iron disc was the component that finally made the stove function properly. I had tried different combinations of old skillet/natural draft/compressed air/long skinny burner pan/squirrel cage blower etc. and I was really sick of the whole deal. Different combinations sort of worked, but were finicky and hard to keep lit unless they were just running full throttle.(2-3 gallons per hour.) I took another look at the MENS stoves and decided to go with the heavy disc and draft tube theory. Made the disc and thought I'd try it with my air nozzle setup and lo and behold it worked. I will probably keep tinkering but for now it's freaking cold outside, and I can't work on the stove when it's running.
The one completely successful from the get go part of this project is the DC motor/hydraulic pump oil supply/metering system. I don't use or need a filter, and I'm not particularily careful about what gets dumped in the tank. The DC motor gives me a consistent controlable oil flow into the stove, and I don't worry about oil viscosity and flow changing with ambient temperature like you do with a dripper system. Also no orifice or venturi to clog up. The hydraulic pump is a used small displacement gear pump so it's self priming. Probably runs about 10 rpm so even nasty old used oil should not wear it out very fast.
Hope this helps, YMMV, etc.
02-02-2008, 12:58 AM #11
I wonder if you could scrounge up an old Petro rotary cup burner, they will burn any oil with minor adjustment.
02-02-2008, 01:00 AM #12
02-02-2008, 05:41 AM #13
is there enyway you could draw a print for it would like to make one just like it . and pic would be great . please ...... if you like email them to me [email protected]
02-02-2008, 08:23 AM #14
As long as you don`t have your combustion chamber isolated with refractory and getting real high temperatures (up to1300 Celsius=2300F) that way, your stove is no good
Only with that high temperatures you get maximum combustion
And then cool down the hot gasses gradualy
02-02-2008, 09:17 AM #15
got mine hot enough to melt the ALU discBTW ...
then moved on to cast iron .
BTW ...........soon as its up to temperature the oil vapourises anyway ..........your probably wasting your time trying to atomise it .
had mine running off a chemical dosing pump ...
fully adjustable for feed .....no fancy nozzle or control valve needed.
was just about to go on to the mk2 double headed chemical dosing pump ...
each head independently adjustable
so one can be left on pilot ................and the other on a stat ...
found in a car-boot sale
all the best...markj
02-02-2008, 09:33 AM #16
I'll figure something out guys. I have a photobucket album, but my HP editing software is broken, my Windows 97 computational device needs updated, my camera is crappy, and I'm going to an auction today.
Peter-That is well stated, and what I tried to accomplish with the split level horizontal stove. A non contact thermometer is VERY useful for these projects. Plus, my dog loves the laser pointer.
02-02-2008, 10:11 PM #17
I worked with large heavy oil burners years ago. All were air atomizing, think spray gun. A large forced draft fan from behind the nozzle with turbulator vanes gave the mixture a spin. Refractory combustion chamber was required for nearly complete combustion. Flame could not impinge on refractory or combustion was not complete. Flue gas sampling at the stack gave efficiency. CO2, O2, soot, and temperature were measured. Combustion was never perfect but mechanic kept adjusting air and draft until near perfect. No visible smoke could be seen when adjusted properly except the short time it took to bring the burner up to operating temp. Burners were usually dual fuel. The industry got a big break on natural gas price by having the service interuptible. The same principles apply to all combustion.
02-02-2008, 10:28 PM #18
this sets a different standard ..
as more air goes in and up the chimney it dilutes the smoke ..dilutes the co readings ...and everything else ..
you end up with a heater that does not work as efficiently as its capable of.
so there is a lot of deceiving going on with the industrial ones to please the way the environmentalists measure the emissions..
i could make mine burn five litres an hour ..........with intake wide open ........it would produce no smoke ....but only half heat....set that way
all the best.markj
02-02-2008, 10:51 PM #19
I think we all need to chip in and buy scott (svs) a new camera. lol
I seen a oil burner in this guys shop and it was crude 2'x2' 1/4" plate welded together with car radiators copper coils tanks mounted to the box. It was a drip style with comp air . this ulgy monster heated his shop and house. he said the key is... the air ratio and the feed from the bottom .there was no hot plate he used a propane torch to light it. after a few years of tweeking it's his only heat source
03-02-2008, 10:42 PM #20
Sorry for the delay, but I made a sketch and had it scanned into a pdf file. Turns out photobucket can't deal with a pdf, so I will do a mass email to any one who pm's me their address.