Simple SVO drip into woodstove works good

Space Heating with SVO WVO Vegetable Oil Biofuel.

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Postby mike_belben » Thu Nov 11, 2010 11:56 pm

i recently tried to duplicate your ramp setup by memory from reading about it last year, in my cheapo tractor supply tiny woodstove (who's airflow dynamics must certainly differ from your stove.)

biggest mistake that i made was cutting the hole in the bowl too low, so that fuel can pour out the front in the event the burn rate slows down or excess fuel is supplied. rather than trashing that bowl, i tipped it backward to compensate, making a fuel puddle toward the rear of the bowl, under the ramp. driprate ranges 1drop per second up to a steady stream, and i have liquid running down the ramp toward the front holes. so i cut slits in the ramp (like waterbars on a ski slope) to form a sort of louvered section, and bent those louvers downward to ensure that oil fell into the middle of the bowl to reduce the tendency for spills out the front. this is how i accidentally discovered something of apparent benefit.

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the soot patterns on the ramp or trough as i think of it, having sides.. show absolutely zero buildup on the louvers, and a reduction in carbon deposits along the side walls near the slots. i would assume this indicates a near perfect air/fuel ratio, or that those louvers are running too hot for soot to accumulate? the rest of the ramp has a heavy layer of soft flakey soot. could this be from the inability of fuel to find adequate air?

i am using a pair of DC computer fans wired to a $5 harbor freight AC to DC float charger, to force air under the door of the stove. this nearly doubles the output of the flame. i tried a blow drier but its too much air, and my stove billows smoke at the seams. in spite of the fans, i cant seem to get the thermometer on the smokestack to pass about 280*F. i typically run my stove hot, in the 400-600 range, on a mix of very dry seasoned pine and hardwoods. the veggie im experimenting with is settled and liquid down to 40*F, but has too much water to make drying economical until i get my wood fired dryer going.

some pics
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Postby BrentM » Mon Aug 22, 2011 3:06 pm

That looks like a good flame. The one picture looks like you captured a drop of oil falling. Are the fans a little close to the fire? Are they holding up?
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Last edited by BrentM on Mon Aug 29, 2011 6:03 pm, edited 1 time in total.
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Postby mike_belben » Mon Aug 22, 2011 9:32 pm

i went through a few setups last year. used a pair of computer fans in a shroud that pushed air under the door. the turbulence made for a real pretty flame but low stack temps. i didnt know at the time that too much combustion air really cools your stack and reduces draft, it just wouldnt heat the house, 200F stack is pointless in winter. 300F stack will only heat the basement, takes 400-600* stack for the heat to get upstairs.

the fans are fine, but they werent subject to as much heat as the photo would make you think.

my most tuneable drip setup was this one, breadpan and piece of tin. no fans.
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the sheet serves as an adjustable preheat. adjusting it one way or another increases or reduces the time the oil takes to get to the holes in the middle.

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here you can see water boiling out of the oil puddle.
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when that setup burned out i tried a 2 tier bowl but the large surface area is an issue. has two settings.. slowly dying or burning your house down. i can easily get the whole smokepipe lava orange.
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Postby John Galt » Tue Aug 23, 2011 2:43 am

Why go to so much trouble fiddling with something that will likely burn down the building it's in, and void your insurance in the process?

Mix the UVO with sawdust, pack it in 'cardboard' milk cartons, burn them with a wood fire in a heavy steel airtight woodstove with combustion air control and a firebrick lined firebox.

Simple, easy, cost effective, and most importantly SAFE.
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Postby mike_belben » Tue Aug 23, 2011 4:12 pm

because i spent all my time chasing down dust and cartons to dispose of my several hundred gallons of junk grease.
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Re: Simple SVO drip into woodstove works good

Postby Trashisfree » Sat Dec 01, 2012 4:39 pm

I think the ramp is a very good low tech solution over a clogging nozzle or a regular pot burner. It spreads the oil out so it can vaporize faster.
Run a drop of oil along a piece of metal, it will leave droplets behind. The more surface area the oil has the quicker it can vaporize.
I envision a u channel downward spiral made out of iron

Have you tried adding your forced fresh air 3-4 inches above the ramp, not from underneath? This makes sense, because you want to provide oxygen to vaporized oil, not cooling the unvaporized oil.

From Bruce Woodford's forced-air waste oil heater, a modification of the MEN or Mother Earth News burner.
I originally thought that the closer the air-supply pipe was to the point of combustion, the more efficient the burner would be. I discovered quite by accident that I was wrong! My burns kept getting hotter and hotter even though I was making no changes to the system. I discovered that the end of the air-supply pipe in the burner was slowly eroding away with the heat and the higher it got above the bottom of the burner the hotter the oil burned. So now the end of my air-supply pipe is 9-10" (23-25cm) above the bottom of the burner, 3-4" (8-10cm) above the top of the burner.
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Re: Simple SVO drip into woodstove works good

Postby Trashisfree » Sat Dec 01, 2012 8:09 pm

For a round burner, I believe a series of pieces of U channel welded into a spiral may be the way to go.
Each step water falling to the step below it, everything at a very gentle slope. The gap between steps should act as the slits in your improvement.
The longer the path and the more steps the more efficient it should run as long as oil isn't building up at the bottom.

I also believe that with the right amount of air 3-4 inches above the burner and not building up an oil reservoir below that it should burn far cleaner with less soot.
If you look at the slits in your design the carbon deposits should have built up there, but also were probably burned off there too.
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Re: Simple SVO drip into woodstove works good

Postby mike_belben » Sat Dec 01, 2012 10:10 pm

the biggest hurdle to a drip waste veg heater is 1.) prepping the oil so that its not going to be full of shmeg that clogs your drip valve or water that puts the fire out, and 2.) as temp changes, viscosity changes so the drip speed changes so the temp changes so the viscosity changes so the... you see where im going. the fan was terrible for me, all it did was lower the stack temp and render the stove pointless. soon as i came up with a decent burner, in this case the sheet, it made all the heat we could stand when it wasnt flooding out. the constant fiddling with drip speed was terrible though.

without a mechanism to control feed rate, my experience has been that the stove is either flooding or raging out of control. we have a baby in the house now and i never made time to build an automated drip regulating device, so ive gone back to wood for now, and give my shmeggy grease settling goo to a farmer for pig feed. maybe next year, but id rather a vertical men style unit then that wood stove.
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