Gassifying Drip Oil Fed Rocket Heaters with a Heat Exchanger?

[671jungle]

 Hello everyone. Not forge related but in the realm of our interests. Have any of you made gassifying drip oil fed rocket heaters with a heat exchanger?

This will be the base and wick housing for the greenhouse heater. Super simple design. Attach legs, empty propane bottle for combustion chamber will sit on top with copper tubing running in the cross section for a heat exchanger and a chimney for exhaust.
The drip feed will run down along the combustion chamber before entering and leading to the wick reservoir. The wick will be an “Argand lamp” style wick.

Any critical notes, precautions or additions are welcomed. 
thank you

[671jungle]

Rough idea of the system. I have a sneaking feeling to make the combustion chamber smaller in diameter or cone shaped. The exhaust may need playing with as well.

i am also very interested in the “Argand lamp” wick being that the wick diameter is rather large. The large surface area will hopefully increase output. The center through way of the Argand wick will be 1” or 2” copper tube protruding out the bottom of the reservoir and base. The wick material will be 100% carbon felt. The breather holes in the stainless pan and wick housing are about 1/2” diameter hopefully providing plenty of air for combustion.

1 1/2” or 2” copper tubes for the heat exchanger.

the whole device will be ran on gravity fed vegetable or waste oil.

[Frosty]

I'm not familiar with the argand wick but the stove design looks to be too "flow through" to me. The flame is directed straight into the exhaust stack it sure looks like most of the heat is aimed up the stack. I've found that heat stoves that direct the flame against the stove walls or into the exchanger produce a cooler exhaust and warmer room.

The air intake in the bottom of the stove looks extremely large, is there a way to damp it in use? 

The oil preheat by running the oil feed tube down the inside of the stove reminds me of a design out of Mother Earth News a couple decades ago. I don't see a benefit to running it down the outside of the stove. If you want to preheat the oil use steel tube, brake line works well and wrap it once around the stove wick. That way will bring the oil to close to vaporization  temp. You do NOT want it vaporizing in the tubing and spraying like a steam whistle! It would then allow you to supply the oil from under the stove up through the bottom and minimize the chance of snagging or breaking the line. 

The oil stoves I've owned ALL ran the exhaust stack from the back just below the top of the combustion chamber, the flame was never given a direct path fro the fire pot to the stack, it was forced to remain in the chamber and circulate through the exchanger.

Do you have links I can check out so I know more about the wick you're using? I've only owned pot and wick type oil heaters, I've never done more than basic maintenance type service on them. None of them had a flammable wick, one had an oil preheater / burner similar to that shown in your sketch. I'd like more info, my above impression is based on old memories and intuition so it's suspect.

Frosty The Lucky.

[Buzzkill]

The only stove I've used of that nature is the M1950 Yukon Stove when I was in the Army.  It dripped white gas, kerosene, or diesel into the middle of a relatively thick plate that (after heating up) would cause the fuel to vaporize when it hit.  Two design features of note:  (1) Most of the air was drawn in where the fuel line entered the burner assembly, and (2) There was pretty much maximum distance between the burner and the exhaust port.   I believe that it was designed to draw air in past the fuel line to keep it cool enough so that the fuel would not vaporize in the fuel line before the drip hit the plate.  The second feature of note was to get the most heat into the tent.  

A couple side notes here...  I was in a canvas tent that caught on fire from one of these stoves burning too hot.   They also tended to produce a fair amount of soot which would gradually choke off the exhaust and/or spark arrestor cap.  Our solution was generally frowned upon, but we'd throw a 5.56 blank cartridge in the stove.  When it detonated that would clear out the exhaust pipe and spark arrestor fairly well.

You have a heat exchange system, unlike the M1950,  but I still think you want to keep the hot gases inside the stove as long as reasonably possible to get better efficiency on transferring the heat. Any way that forces the exhaust to take a more circuitous path without decreasing the overall throughput of the exhaust should help there.

[671jungle]

3 hours ago, Frosty said:

Do you have links I can check out so I know more about the wick you're using?

Thank you Frosty. I have thought on all those points. Mostly coming up with a stainless baffle to interrupt the flame and help with secondary combustion or more heat exchangers running through the flame path to act the same and increase heat transfer. Any other thoughts?

here is a video and a basic diagram of the wick. The guy in the video is cut from a similar cloth as most of us here in IFI.

 

1 hour ago, Buzzkill said:

A couple side notes here

Thanks for the response. 
i like the idea of a “hot plate” vaporizer. I am curious if a baffle on the flame front would help with secondary combustion. 

As far as intake and exhaust:

1) can the intake remain oversize to accommodate as much air as needed for combustion?

2) can the heat exchangers as a baffle to interrupt the flame? or would it be better to reorient the exhaust all together? 
thanks for the time!

 

[Buzzkill]

I'm not sure how thick the fuel can be and still function with that setup.  We were in temps as low as -50 degrees F when using those, so the fuels we used had to flow at extremely cold temperatures.  IIRC the burner had a top plate with the fuel line screwed into the center of it and a thicker bottom plate where the drips would hit.  The plates were separated just a little so that when the fuel evaporated it burned around the circumference of the plates.  Most of the intake air came from above the burner, so that helped pull the flame down into the stove.   The front door of the stove had a sliding gate to help fine tune the intake air.

Having only used this stove and never built or experimented with any designs I'm afraid I'd only be offering educated guesses regarding your questions.  The closest thing I built and used was a forge/burner combination that was fueled by used motor oil.  However, I used compressed air and a siphon nozzle to atomize the oil rather than using a gravity/evaporation system.  I also started the forge using kerosene or diesel fuel until hot and then switched to used oil.  It was fairly difficult to keep it lit with just used oil when it was cold.   The wick system may allow for thicker fuels to be ignited more easily before everything gets heated significantly.

 

[Frosty]

That looks like a better soot generator than heater. About the closest thing I'm aware of as a reasonably effective waste oil heater was a pottery kiln with a blower on the draft. He burned kerosene till the cast iron frying pan drip plate was hot then switched to waste oil. It fired cone 6-8 pottery easily but it was a really janky machine. The jet was copper tubing folded tight with one corner filed until oil dripped at the rate he liked. Intake air is what kept the copper from melting.

It worked . . . until the power went off for a little while and melted the "jet" when the power company restored it the kiln was a raging torch until the air hit it and it spread burning waste oil around the front yard. It inferno wasn't as big as the neighborhood kids said the burn dirt that was lawn was maybe 25' in Dia. 

The drip burner stoves I had a look inside were about like Buzz describes above though the drip pan I recall most clearly was fluted axially with a lip, the top plate and drip pans were were really close 1/8" max. if memory serves. The fire box was thin too, maybe 18ga. The stove pipe was probably 4-6" from the top of the box and 4" Dia +/-. It burned stove oil, Kerosene was too light and not recommended. 

Getting waste oil to flow in winter would be the trick. In or next to the stove is no challenge but getting it from the storage tank to the stove is a different kettle of chipmunks. Who in their right mind would want the oil tank next to a home made oil stove or even in the same room?

how about rather than the complex nested tube and absorbent wick for the burner we substitute a vertical steel tubing coil with small holes drilled above centerline of the tubing. The central air intake would be centered in the coil the space to be determined. 

Waste oil is pre-warmed by a basic convection driven liquid heat exchange coil. One in the oil tank and heating loop against the stove chamber. "Antifreeze" solution is heated in a loop around the fire chamber and is carried by convection to the oil tank, chilled antifreeze returns to the heat loop through an expansion chamber. Being as it's all part of the same component the oil line would travel in contact with the hot leg of the heat exchange or if we get crazy about it IN the hot leg of the heat exchange hot leg.

That's how the fuel is kept liquid, it flows into the vaporizer coil and oil vapor is directed against the walls of the super heated burner into the pre heated combustion air.

The draft is directed against the outside of the burner combustion pot to be preheated while cooling the combustion pot below damaging temps. 

Once warmed up the fuel vapor heated well above it's flash temp WILL combust immediately as it enters the air flow. As long as there is an excess of air the stack and fire box will stay clean. Except contaminants in the waste oil of course. The state vehicle shop installed waste oil furnaces on the promise that between saved fuel and oil disposal costs they'd be  money ahead. As it turned out the filtration and treatment system alone cost more than several years total heating and cooling for the building, the maintenance was nearly as expensive as the old fuel oil, it never met clean air specs. Worst of all the haz mat disposal for the chemicals used to treat the oil and resultant residue was ruinous. Not to mention the "treatment" equipment used an entire shop bay. 

When it was new lots of us stopped in to take a look but the 55gl. drums of 70% peroxide scared everybody who knew what it is off. The treatment system enjoyed the nick name, Rocket Room.

It lasted less than 2 years as heat and took a couple to find someone to remove it all. The company that sold it to the state was long bankrupt so they skated on making good. 

I like oil heat, it's what's making our house comfy as I type but it's not waste oil. 

I don't know if one of the people making bio diesel from waste fryer oil is still in business but I haven't heard anything in a couple few years. I use waste fryer oil from the Safeway deli for what little quenching I do. 

Frosty The Lucky.