Building a waste oil burning stove for my shop

[Donman]

Thanks for the drawing Dogbreath108. I must have done something wrong when I built one that was almost identical to your drawing. It worked really well at first - threw amazing amounts of heat, but coked up so bad after 3 or 4 hours that it took that long to clean and reset. Did you build your design? Can you post pics? You must have a lot of experience because you seem pretty emphatic that - that is the way to go. Where does all the crap out of the oil go if it doesn't go in the bottom pan? Do the pans get red hot?

 

[patrick_g]

Donman, Some of the designs vaporize the contaminated fuel before it wets a surface in the burner. The combustible portion of the fuel combusts and the non-burnable fraction ends up a light dry powder which literally "goes up in smoke", i.e. it is carried up up and away in the exhausted fumes. In some cases it doesn't all make it and a variable residual quantity remains behind to be cleaned out by the operator.

I have never designed/built a waste oil burner but did inherit one when I bought my current holdings. Prior to that my only waste oil burning experience was when working my first engineering job with the Government. I was energy conservation officer of SUBASE San Diego. We contracted to have a trucker haul contaminated fuels, used lube oils, and such from the sub tenders as well as the effluent from the auto hobby shop and take it to Miramar Naval Air Station (then home of Top Gun training squadron) where it was burned to fire boilers to generate electricity. We did have to jump through some regulatory hoops to get the burners certified but made it with flying colors.

Then someone in the great state of California decided that diesel fuel, or any fuel oil or gasoline with water in it or any mixture of fuels (a little gasoline in a tank of diesel is hazordous waste) or just used motor oil was in fact dangerous HAZARDOUS WASTE that required lots of close supervision and had to be trucked by specially certified trucking outfits at great expense. That is when we lost the nearly free fuel to make cheap electricity because we contacted an oil reclaimer and GAVE them all our fuel and oil waste for free for hauling it away. The costs associated wlth the "proper" handling of our HAZARDOUS waste wiped out the incentive of using it for fuel. Thanks Kalifornica!

My arms length experience with waste oil burners was that they can burn really clean and even if required to use scrubbers on the stack gas it is not a difficult solution/situation.

Pat

 

[skidsteer.ca]

[/QUOTE] I attached a quick sketch (sorry about the quality as I am headed out the door in about 10 mins.) This is a proven design and a easy build. The oil and air are metered. The chamber gets very hot and holds the heat which is key to burning all the soot and crud. I used 1 ton brake drums but any size could be used if you adapt the design around it. I'm thinking heavy truck drums would work well, but you need much more btu's to make it efficient.[/QUOTE]

The drawing is simular to what I doing over a wood fire. Once the stove reaches 500 degrees f the flames jump up to my pressure washer nozzle and burn the oil/air mix right out of the nozzel. I close the draft that comes in from beneath the wood and keep a draft open in the door in front of the wood. It makes plenty of heat and to date the problems have been limited to cleaning the nozzle going into the stove and re routing the plastic shop air lines that melted from the intensity of the 950 degree stove.
I keep about 40 psi feeding the oil and the air. I tried 2 separate regulators on each at first. The air does not require much pressure (15 to 20 psi) But then a clogged nozzle would allow the oil to back up though the air line and exhaust out the air line regulator set at the lower pressure. So now both run off the same regulator at 40 psi.
Both lines have a variable restriction just before the nozzle. This is were I drop the air pressure to between 15 and 20 psi. The oil line is controled by a 1/4" hydraulic flow control valve. Any more then 2 turns open on this will produce a solid stream of oil out the .050" nozzle.
I T'd both line into a 3/8" npt pipe that is welded though the front wall of the stove by the door. I had to add 2 45 degree fitting inside the stove to point the spray just over the top of the burning wood
I only open it 1.5 turns for lighting the wood. Once it is burning somewhere between 3/8 and 3/4 of a turn is enough to provide a steady flame out the nozzle and hopefully keep the stove under 850 degrees. When the shop is up to temp I shut the oil valve and allow the air to purge and cool the nozzel
I figure it has cut my firewood use in 1/2.
To date we have used about a 100 lb lp tank of used motor oil. The oil supply in last better then anticipated.
I'm considering a smaller nozzel diameter, hoping this will allow a steady flame at the nozzle with the oil flow set lower. Anything below 3/8 and the flame goes out then catches with a poof (small explosion) that can expell smoke out of the stoves draft. To date it puts out more heat then my 2400 sq ft shop needs and it only burns for 2 to 3 hours out of a 8 hour day. Then whe shut it down until the next morning
Ken

 

[skidsteer.ca]

Here is a video of the burn,
one of the outside temp and
a final overviewing the system

YouTube - Wood & Waste Oil Burning stove

YouTube - oil burning stove temp

YouTube - Waste Oil & wood burning stove heater furnace

Ken

 

[dogbreath108]

For just the forced air burner design, one thing to keep in mind in unsatisfactory burns is that the volumn size burner that you are building has a limit and a sweet spot. air/fuel(which has a lot of variables)/ and chamber temp.

(just hang in with me here a minute, as this may be common sense to some guys, but it will help those that have not quite narrowed this down...). Its sort of the same way you can get a gas engine to run good by adjusting the carb. A gas engine is a little more stable because gas usually has the same consistancy. Your outside temp is your "chamber" that is pulling heat away from the engine (and effecting burn temperature). This is why you have a choke and a thermostat. If you had once found the sweet spot on your home made chamber oil burner, it probably would be fine for long term use. But the heat load may have slowly changed, the oil viscosity most definately changed (which is why a small metering pump works best). (Hopefully your air feed stayed the same). Gravity flow or a pressurized oil vessel for your oil feed all will work, but there is no way to adjust for the temperature rise or drop and the viscosity change of the oil. This matters A LOT. The pump also helps with the difference in waste oil that you will burn. Sometimes it may be thin consistant, other times you could have a bit heaver stuff with maybe grease gun globs or who knows what else in it. nun the less it will always effect your burn so you filter it good and try to hold it on the straight and narrow to get expected results. I knew a guy who always tried to mix his waste oil to have the same consistancy, blending with different types (I think he was always adding a little heating oil/diesel into it). I'm talking, he spent some time at it (mixing, stiring,dipping sticks in it etc)... More than I would. But he was defininately happy in doing it, so he was getting very good results.
Also keep in mind if your fuel line/feed line/drip line or whatever you want to call it is too close to the chamber, it will get too hot and start burning the oil inside and clog. This obviously having nothing to do with what I just mentioned above. This clogging why it should be up fairly high inside the feed air line so that the cooler air flow brings the oil in. ( Heat soak after shutting the burner down will do the same thing). Eventually the air feed line and the oil feed line will need replacement because the surroundings, but it shouldn't be because it keeps clogging. Just the you wore it out with fairly high run times
I haven't been on this site in a while, but I think about another month on the subject and it will die out due to Spring weather around the corner. (well who's up for making a waste oil burner to heat your pool water . In the meantime I hope this helps somebody on their project...

 

[LetsRoll]

Just an update on a few test I've ran these few last weeks. I've finally give up on the air induction like the article that I posted to in my first post. The drip method produces so much soot and the conical gets buildup all over it which causes a lower temperture burn. Also, not all of the oil is burnt off the conical. I could not get a complete clean burn. I was still having some black smoke coming out of the exhaust pipe outside. What I did was, install a bigger oil line and a hydraulic flow control valve. Thanks Ken for the idea on the adjustable flow control valve. I watched your video and as soon as I seen the valve, I knew that was the answer to my oil flow problem. I was using a plug valve but it wasn't big enough, so I put on a ball valve which wouldn't let me regulate the oil flow. The hydraulic flow control valve was the answer for oil flow control. I still have the ball valve installed on my line, but its only used as a on and off valve. That allows me to keep my setting on the flow control valve. Dogbreath108, I tried your method and like Don said, it got dirty after a few hours of use. I just could not get the temperture up to completely burn all of the oil. Which resulted in a ton of soot and unburnt oil all over the inside of the brake drums. My present setup is built just like the PDF drawing you posted using brake drums and the down pipe air induction. So, I've decided to go back to atomizing the oil by using compressed air. The pictures I posted earlier were from my test using compressed air to atomize the oil. I didnt want to go this route cause my compressor uses a ton of electricity to operate. But I decided, this will be the route I'll be taking to get a clean burn. I might try a atomizing nozzle like this Siphon Type SNA Air Atomized Nozzles. Or I might try a nozzle from a pressure washer like Ken is using on his stove. I might be able to get away with using only 15 lbs of air pressure cause I'm using a 3/8" oil line. 3/8" is big, but that is the outer diameter (OD) of the copper line. The inner diameter is 1/4" (ID). And my hydraulic flow control valve is 1/4" (flows 6 gallons per minute-hydraulic fluid under high pressure). 1/4" ID oil line will allow me to get the heat up faster in my shop. Ok, I'm going to try to explain this cause I dont have any pictures. The other day, after not being happy about the downdraft method. I built a flame thrower type nozzle. Consisted of a 3/8" black pipe and a 3/8" black pipe T fitting. The air line was screwed into the end of the pipe. The T was screwed onto the straight pipe. The oil line was screwed into the T. I welded a small bracket to the pipe and at the end of the bracket. I bent the bracket at a 90 degree angle. The 90 degree angle was about 4 inches away from the end of the pipe. I pressurized my oil tank with 30 lbs of air pressure. I had a air pressure regulator on the end of the air line that was screwed into the pipe. I adjusted the air pressure to about 30 lbs. I also had a ball valve right after the air pressure regulator. Were the oil line was screwed into the pipe was a ball valve as well. I took this flame thrower and had it clamped/straped to my welding table (I can roll/move it around my shop). I had it aimed outside of my pull up door. Actually, it was about two feet out side of the door of my shop. I got the air and oil flow right by shooting it into a 55 gallon burn barrel that I used for burning thrash. After getting the air and oil flow right. I lit the stream with my blow torch. And had a flame coming out of the end of the pipe about two feet. The bracket end that was bent at a 90 degree angle, stayed HOT and kept the flame going incase some water come out of the air line. I decided now was the time to see how big of a flame I could make with a 1/4" oil line. I kept turning the air pressure and oil flow up. I did this real slow to keep the flame stable. After several and I mean several minutes, I had the oil line only half way open and the air pressure regulator was up to 80 pounds. I had to turn the oil off cause I could not handle the heat that was coming from the flame. I had a flame that was about 5 feet long and it was producing a ton of heat. After doing this, I decided this was the route I will be taking. NO more downdraft methods for me. I should have got some pictures but I didn't want to leave the flame unattended. One problem that I had with the flame, there was some smoke at the end of the flame. Once I put this inside of my stove. I'll have to build a back stop for the flame. The flame will hit this back stop and keep it red hot. The hot metal will burn anything that doesn't get burnt by the flame. Hopefully I've explained this so you guys get a picture in your head of what I'm talking about. One other thing, once I get this setup inside of my stove. I will not need a hot stick to keep the flame going. The back stop will do that for me.

The downdraft was the method I tried using but it produces allot of soot and cleaning is a most after every use. Vaporizing Waste Oil

 

[Donman]

I finally had a 2-3 hr time slot to play with my bottom feed waste oil heater too.
I think it is going to work! My temporary oil feed box worked fine but my clear vinyl flexible feed line didn't. I cut it a little too long so it needed a coil in it to shorten it up and then it kinked and got an air bubble in it. I had the unit hooked up to my good chimney so I really wanted to try the burn in the time I had so I resorted to use the pump oiler method to put oil into the top of the sight glass standpipe next to the heater. This worked OK but varied the oil level in the conical more than I liked. A squirt every couple of minutes worked the best Even so it burned that way for a couple of hours and gave me a good handle on how much air was necessary for a good clean burn. A white flame will burn with almost no smoke and soot, and an orange flame is both smoky and sooty. More oil in the conical requires more air to burn white flames and less oil means less air is needed. Feeding oil from the bottom seems to work very well. The boiling oil moves from the center to the outside of the conical along with the air from above and produces a sideways moving flame that also heats the conical so the process is self sustaining. While it was burning with the bright white flame I went outside to look at the chimney and saw mainly heat waves with just a tinge of gray smoke coming out. After the burn I looked inside expecting to see soot hanging from the inside surfaces but didn't find any. This setup can burn very clean as long as the air/fuel ratios are right and I think I can make that happen, but it will never throw large amounts of heat like the atomiser method you guys are using. My guess is a steady 40 to 50 thousand BTU is all this heater will produce but that is really all I need.

 

[SPIKER]

One thing about the back stop for the stove, maybe just helping, is to use a rolled hunk of perforated stainless steel and burn into that like burning into a pipe (one long enough to keep the flame length inside it with a smaller opening at the exit end to back up some slight bit of pressure.) this will get nice & hot, being Stainless Steel it should take it OK, I would still suggest some 16 gauge or better for that.

mark M

 

[DRL]

Donman, got any pixs. Good progress.
DRL

 

[patrick_g]

I have enjoyed reading of the adventures in waste oil burning. I had wondered what sources of fuel could be easily or economically exploited if the stove owners own personal waste oil stream was too small to meet the winter heating requirements.

Yesterday I took delivery of approximately 300 gal of #2 diesel (off road red) and for the first time paid attention to the details of the delivery process. The hose on the powered reel which is used to fill my tank was purged by the operator to clean out the material delivered to the previous customer. This is a pretty large diameter hose about 50 ft or so long. It was purged by pumping diesel through it. The diesel, mixed with the previously dispensed liquid (unleaded gasoline) was deposited into a waste tank on board the delivery truck. Probability theory suggests that many of the deliveries will require hose purging during a day of deliveries.

I asked the driver what they did with the mixed fuels in the truck's waste tank and he said they offload to a waste tank back at "the office." I inquired as to the disposition of the waste fuels and he said farmers buy it for various uses such as mixing with weed spray, starting brush fires or whatever. It might be worth looking into such sources of mixed fuel as a supplemental fuel source for a waste oil burner. Once fuel types are mixed, the resultant (in more civilized and regulated states like the Socialist Republic of California) is considered hazordous waste and must be handles accordingly. In some states, the mixed waste from delivery trucks may be a source to be tapped.

Pat