Waste Vegetable Oil rocket fuel HELP !!!

Hi

I've been working on a RMH and, on the basis I can get it free, I've tried using WVO as the fuel.

It works really well in addition to wood but on its own remains smoky.

Rather than reinvent the wheel I thought I'd check out what other people have done 

I think its a temperature related problem. The intense heat required for after burnng the smoke doesn't seem to be reached using WVO .......... Help !!

OK did a bit more tinkering with this today.
Original set up was a round container filled with rock wool filled with WVO, small cotton waste wick to get it started. The rock wool stops it becoming a chip pan fire 

Changed the set up to a long narrow pan 2/3 of which was within the tunnel - this increased the surface area of WVO and I reduced the amount of rock wool. The end result is a controlled chip pan fire..... well a contained chip pan fire anyway!!

Burned clean ......... well cleanish ... took longer than wood to get up to heat but once there worked fine.

I think part of it is airflow related. I need to change the set up to ensure all the airflow is above the surface of the oil and I think change the shape of the tunnel so that its wider but lower - I'm hoping that will increase the turbulence and efficiency of the burn.
As this set up is at the "pile of bricks" stage I'll give it a try tomorrow

Any and all thoughts welcome 

I too am interested in being able to incorporate WVO and from all the videos and research I have read on WVO it sounds like you have too much oil trying to be burned at one time. Many youtube videos show a completely clean burning system. The one thing they all seem to have in common is they all work on a drip system. I have not been able to work out a good catch system for the ash that is left behind and won't interfear with the biomass burn.

In the end it may not be an issue if the rocket stove reburn is hot enough to eliminate the ash issue altogether. I would think adding a WVO drip system should be pretty straight foreward and should stop your smoke problem. If you try it let me know if it fixes the problem.

Thanks for the input - I think you're right that there is a balance to be found between the available quantity of fuel and air intake to ensure a steady clean burn

I have looked at drip systems but they all rely on a pre heated flash tray that vaporises the oil. I'm sure you could incorporate that into an RMH that uses other fuels as well as WVO but I wanted to only use WVO.

Also lots of WVO are solid at room temperature so presumably makes drip systems tricky ?

The clean burn oil burners -  that I've seen - use forced air to accelerate and complete the burn. I am hoping the "natural" forced air of a rocket will have the same effect without needing an electric fan..... Haven't got electricity on site anyway !!

One of the oddities of a rocket is that the air flow results in a relatively cool area above the burn site as air is sucked in past the burn. With oil it seems that the hotter the oil the better and cleaner the burn.

So I need to allow the oil to heat up fast and stay hot and get a lot of air moving through the burning/vaporising oil as it moves across the surface of the burning oil and through the burn tunnel and upriser.

Part of the problem with the "pile of bricks" experiment set up I have right now is low insulation of the upriser - gonna fix that asap .

I'm really surprised that no one else has tried this  I'm worried that this probably means I've missed something basic and everyones too polite to point it out !! 

There has to be a pyromaniac out there who's played with burning oil !!  Maybe they're still bandaged up and can't type yet

?WVO?

I was just thinking about your reply and when I reread it a thought came to me. Correct me if I am wrong but doesn't the temperature in the upriser reach some where around 1800 degrees +/- ? If your drip system is placed in the lower part of the upriser you should have the temperatures needed for a clean burn. It would not take long for the internal temperatures to reach oil burning temperatures. At which time you could start your WVO drip.....

As for the issue of using some WVO (waste vegetable oil) that become solid at room temperature. you might be able to get around that by storing it in a metal container that can be placed on top of the drum until it warms to a liquid state then suspend it above the drum just high enough to keep it liquid. If your drip system had a Y connection you could always start it from a smaller container or liquid oil then turn a valve to switch to your solid oil once it is warmed. 

Here is a video of a WVO that uses no fans or blowers-
http://www.youtube.com/watch?v=4lwSmYz_g6U&feature=related

I think the design of the RMH produces more heat then the standard WVO and would burn far cleaner.

Hoser WVO = Waste Vegetable Oil

Sorry - I changed the subject line .... maybe that was why no one knew what I was on about !!

JML

Thanks for the link - love to have seen more of the burn tray and how it was set up, but impressive results.

Like all standard heater systems it has to be adapted to the peculiarities of a rocket..........

Like you say a rocket generally reaches higher temps so at least theoretically it should work.............. I'll  play some more 

I have a limit to the height of the upriser so mine might not be long enough to allow a complete burn without the tunnel as well - but its an interesting idea

I'm doing this as a zero cost thing - per force as well as on principle  - I do have a great scrapyard nearby so I'll see if they have the valves etc.

One of the things that appealed to me was the self feed nature of WVO as opposed to wood - run it for a couple of hours everyday without too much messing about. Not that I mind messing with fire to be honest 

Since your first reply I've been thinking about a pre heated pan for  drip burning or possibly a metal gauze to increase and even out the heat in a oil reservoir burner like I'm using now............ I think a gauze would heat up fast and act as a combustion surface ..... maybe a tube of gauze within the upriser would increase the efficiency............ hmm more food for thought 

Thought this was going to be a quick job when I started !!

Keep thinking - 2 heads definitely better than one 

Roger

Here is another link to see more of the drip tray....

http://www.youtube.com/user/ozzirt#p/u/7/46vbCxR47pw

I noticed that the temperatures in his videos are in celcius, so at the optimal burn of 600 degrees C is 1112 degrees F far lower temperatures then what the RMH will reach in the reburn chamber/upriser.

I already subscribe to his channel but I can't send him a message until he accepts a friend request. When and if he does I will see if he's willing to share the plans. I think that will go along way to blending the WVO with the RMH.

Jeanne

I just found this online.....

http://i303.photobucket.com/albums/nn133/ozzirt/Heater.gif

It is not real clear on details but it might give you a better understanding until the plans can be located.

Jeanne

Roger I found another forum where ozzirt has posted the plans on.

http://www.boards.ie/vbulletin/showthread.php?t=2055664086

Scroll down to the 9th reply and you will see the links for front and side views.  I hope this helps.

Jeanne

thanks for all the input - seems we're the only ones mad enough to play with burning oil ......... which given the number of friendly nutters in here is kind of disappointing 

Really interesting links thanks a lot

Slightly confused about air intake to his first burn pan - but interesting that he has extra air intakes at the secondary burn tube - that might be possible in a rocket - I'll add it to the list of things to play with 

Spent an hour staring at the prototype today - you can't beat giving things a good stare at !!
just added some wood to the WVO and it burned clean and strong........... The extra kick of energy seems to be enough and would seem to put the lie to it being purely air flow rates- I note ozzirt uses waste engine oil rather than veg oil maybe there is an inherent difference in energy in the 2 oils...............

hmmmm need to give it another good stare 

OK time for an up date ........

I've tried drip feeds - all I got was a lot of smoke ..... I think because of the open nature of the burn area the temperature is too low for a full vaporisation and burn - pity but it was a more complicated arrangement than I was hoping for anyway.

Open "chip pan" burning does work but again produces an incomplete burn - pretty good but not completely smokeless. The bigger problem is that the heat up and cool down phases are longer than burning wood and at these stages you do get more smoke.

I know you get smoke briefly at start up and slightly longer on cool down with wood as well.

The other big problem is that even with a half litre of oil in a shallow metal pan the heat produced isn't as intense as a wood fire and the rocket effect is low - this produces a problem with occasional smokeback and lower than average temperatures reached.

I am toying with trying an inclosed burn box with  air intakes under the oil pan. Maybe the higher temps at the oil surface will improve the heat output and accelerate the burn/vaporising of oil............ it means sealing the burn tunnel and having higher temps there too.......... I fear that without really efficient insulation this may reduce the heat at the riser and I'll still have an incomplete burn.

Its really frustrating because on the face of it this should be a no brainer 

The pragmatic response is to combine wood and WVO.

This works well - tried drip feed but tbh the oil pan method is way easier and more effective. Using both fuels raises the temp to good rockety performance levels and reduces the amount of wood used by half 

Not quite what I was hoping for but a good use of free fuel all the same.

What I could do with is some follow up experiments from other people 

If someone with a good RMH that works well using wood as fuel, could try a couple of variation burns using just oil and then oil and wood . The problem is I'm using a "pile of bricks" setup prior to building this system so there are a few too many variables for my liking.

Also  - although I'm aiming to build a traditional RMH (cob etc) maybe someone with a metal system could give it a try........ it may be that a metal burn tunnel etc will heat up quicker and be more effective than a cob/brick system

Paul you could try it in your portable RMH too !!

Help please 

How about using WVO asa supplement instead of a primary fuel source?  eg oil soaked wood.  RMH seems idealised for solid fuels.  Just a thought.

WVO being somewhat scarce in my area, I had not really been following this thread. We had someone in the area build a biodiesel setup and then found they could not get the oil to process... Anyway, Air intake should be about 1/4 CSA. The burn area should be really well insulated, It needs to be hot. In a normal RMH the fuel blocks the intake by quite a lot and the fuel itself acts as insulation for a lot of the flame front. With the oil, you need to create that hot spot. You fuel tray might be best with a very light rock like pumice (BBQ lava rock?) that will also insulate the flame. I found a pipe from the intake through the fire to just before the riser for secondary burn helped (with wood... so your mileage may vary). Fire needs air, fuel and HEAT to happen. A wick or drip may be needed to separate the cool fuel from the burn area. I'm thinking a wicking system like the old white gas "catalytic heaters". The fuel is close enough to stay warm enough to flow, but far away enough not to cool the flame.

Another thought I had is to look at the weight of the oil as a measure of potential heat content. Just as a reference the weight of the wood for a two hour burn in a masonry heater is about 35lbs... I think a RMH heater takes longer to go through the same amount. Take off 10 to 15% for water in the wood. It may be possible to figure out the range of fuel weight that needs to be in the burn chamber at any one time... experimenting may be faster too 

Just some thoughts... don't know if any of them will help.

     I had about 20 gallons of used deep fry oil which was left behind at a demolition project. I used some of it as chainsaw bar oil and the rest I burned in the wood stove quite successfully. It didn't burn worth a damn on its own but when I soaked dry wood in the oil they burned for a long time just like those artificial fireplace logs. Some of the wood sat in the oil for one week. They were fairly thin slabs and became saturated. I got a good fire going with regular wood and then used the oily stuff. It ends up working like a wick.

    If your riser is easily removable it might be wise to check and see if you have gummed up the system beyond the riser. If so you're going to need to contact someone with much more experience than me. I assume this would not be a good state of affairs.

     If you have an unlimited supply of this oil it might make sense to get a diesel truck or tractor and to process the oil for that purpose. The world is full of little sticks which will power a rocket stove. It's not full of diesel fuel.

Hey Len, you might be onto something with the lava rocks.

Thanks for all the suggestions - that's this weekend sorted trying them out 

I've already altered the feed tube on mine and the temperature around the burn area has increased dramatically.......... so I was going to retry the drip feed idea.

I think the likelihood is it'll end up as an additional fuel rather than a sole fuel but I'll keep playing

I'll post any feed back as it happens 

RNM35, a daft idea, but the rocket you want, i think i can envision in my head.

Instead of a J shape, make it L shape. With a very flat and wide inlet. I'd do something in the ten inch wide and 2 inch thick. Along thoses lines, a bit long, may be ten inch or a bit more, insulated  underneath and on the sides, a big square box on top, wich gets heated up, and plenty of litle holes, tiny ones dripping oil. You would start it with a blowlamp. Which would heat up the oil above, and light it. I'm wondering, the box needs to be closed, but, with a presure relief valve, or using the presure, created by the heating uo, to force feed the  oil.  Or, another idea, a  presure relief tube which would go in the intake, after the litle holes, this would throw oil fumes, which would light pretty easy. Even if it flamesback in the box, no prob, the lack of oxygen in there would put the flame off.

Along thoses lines, a completely crazy idea.



Make the rocket something like 6 to 8, with another tube in the midle of the heat rised, closed at both ends, something like One or two inch in diameter. This would be filled with oil, and have a litle tube at the bottom, which would go into the rocket inlet, with a thing like a furnace injector. Heat would push the oil out, by means of expansion of the oil itself at first, and then expansion of the fumes of evaporated oil. Then on top of this tube, you have a feed tube, with an anti return valve, and something like a primer pump from a diesel injection pump, or an hydraulic manual pump, something along thoses lines, to build up some presure in the tube, and also fill it up. I think, for the first fill, you'd need a litle vent on top of the oil heater tube, which can only open towards the inside.   Somethiing along the lines of a  plant sprayer. in which the presure is built up by the hand pump.

Satamax thanks for the confidence in my metal working skills but i fear they're misplaced 

I thought the same as you re wide shallow burn area but todays experiment doesn't look hopeful - I'll post a vid later but it wasn't a success !!

RNM35 wrote:
Satamax thanks for the confidence in my metal working skills but i fear they're misplaced 

sheet metal is not too hard to work with. Look for a contractor that does lots of ductwork as they pull out lots of "waste" tin. Easy to bend which ever way... probably high heat silicone will seal anything you miss so it won't leak and the fuel will keep it below 700C where silicone vapourizes. I happen to have gotten an old RV trailer (25ft) that still had the tin covering the bottom... so I have about 20x8 feet of the stuff... less what I have already used

Will be interested to see the video later. I am wondering if that was the problem with my last burn. The wood looked dry and was not painted, but when I split it part way through the burn it seemed wet or oily inside. It has been under cover for years so it is very dry water wise, but I wonder if the old owner of the property had soaked it in oil to preserve it (it had been the frame of a green house)... even though the one end was rotted right off. It burned but the flame front was about 1/3 to 1/2 what I had been seeing before. And it went out when left for a while even though there was still more fuel. I have seen some deadfall on my way home from work... enough to fill my pickup. I will have to take my saw out and collect it.... If I can just get some time.

Just had another idea... I'm thinking pan with rock bed perhaps with some oil in it to burn at least to start. Then a metal tube over top but inside the burn area so it gets hot. plugged at one end but full of small (tiny) holes. The unplugged end goes to a one way valve and then a gravity feed oil supply. The flame from below heats the pipe forcing the oil out like through a diesel injector in a mist and hopefully burns like crazy. As the oil in the tube gets used up, the fire dies down a bit (hopefully doesn't go out may need the pan under to have a supply of oil too) and the tube cools down letting in more new oil and cycles over again. There may need to be a "trap" (think under the sink) between injector pipe and the one way valve to keep hot oil from rising in the supply.

I made a small foundry using waste oil (haven't tried WVO). I start it with a propane feed and then start the oil drip and turn off the propane as it takes off. I use an old vacuum cleaner to supply the air, I still need to attach some sort of voltage regulator because it's way too much air. The oil drip tube runs right down the middle of the air / propane feed tube and ends just short of the end of the feed tube, the high velocity of the air vaporizes the oil before it enters the combustion area. I don't have a thermometer to measure it but it's hot enough to liquify aluminum very quickly. (My nephew dropped a soda can in it on one of the initial burns and it the whole can dripped out the bottom in seconds. Didn't have a crucible in it at the time.) It's packed away at the moment, since I haven't done any casting for a while, but maybe I can dig it out and get some video, or at least some pics.

I'll try to find the link that provided the inspiration. You might be well served looking into what the casting a forging communities do. I see some similarities; making a really hot clean burn, materials to withstand the heat, insulation, make it cheap, make it yourself, recycle.

JML JML wrote:Here is another link to see more of the drip tray....
[url=http://www.youtube.com/user/ozzirt#p/u/7/46vbCxR47pw]
http://www.youtube.com/user/ozzirt#p/u/7/46vbCxR47pw[/url]

I noticed that the temperatures in his videos are in celcius, so at the optimal burn of 600 degrees C is 1112 degrees F far lower temperatures then what the RMH will reach in the reburn chamber/upriser.

I already subscribe to his channel but I can't send him a message until he accepts a friend request. When and if he does I will see if he's willing to share the plans. I think that will go along way to blending the WVO with the RMH.

Jeanne

I just found this site.

How may I help?

Ozzirt (Spike)

hmm I just found this. if you want the thing to burn clean you need to provide air in the volume the very rich veggy oil needs to burn clean. IE. you will have to do forced air. cause thats the only way to get the volume.
you can set the stove up like a diesel stove with a pumice wick in a pot and it will work well as long as it gets the air it needs. Dunno why folks want to make all these things so complicated.

Hmmm why make things so complicated ?? .............. not sure but its a habit I'm trying to break Actually sounded kind of simple and obvious until I tried it - I've used veg oil lamps in India and given the free supply thought it would be a nice easy fuel. and one that could be set up with minimum attention during the burn......... Ahh well how wrong can one man be !

Actually it is easy IF you use it as a supplement - wood soaked in veg oil added to the fuel works well and lasts a long time - you just cant use too much in the mix. Certainly for me the extra hassle of adding forced air etc is too much like hard work - but I guess might be worth it for others.

Roger

I've just found it too, and after a while lurking I thought I'd better register. I spend my working time looking after peoples oil burner installations, and come across both pressure jet and vapourising types. WVO would be better run in a pressure jet burner, with pressure developed either by a motor driven pump, or compressed air. This is needed to atomise the fuel so the combustion is clean. Too low pressure gives a dribbly output from the nozzle. The burn would be a bang-bang set up, as the minimum output will be around 10kW (lots of heat, more suited to a foundry if burnt continuously). It would also need an electric supply of around 250W. So you'd need some of the WVO to run the generator. In this case use all the WVO to run a generator and duct the heat from the generator to make use of it.

For vapourisers, the oil is usually drip fed into a burner, and would usually be thinner than WVO (ie vapourising oil). To get clean combustion, the air must match the fuel. This means you need tight control of the oil supply, and a stable flue draught. The vapouriser can burn continuously and has a rough output of around 2 to 4kW. There is some lattitude in the air/fuel mix, but this is obtained by the oil burning with a high temperature part in the burner to vapourise the oil (hence the name).

I haven't done anything trying to burn oil in a rocket stove, because wood is so much more convenient as a fuel, and I suspect oil would cause more trouble than I need. Also when TSHTF, any oil will be useful for making other products.

Roy Clarke wrote:I've just found it too, and after a while lurking I thought I'd better register. I spend my working time looking after peoples oil burner installations, and come across both pressure jet and vapourising types. WVO would be better run in a pressure jet burner, with pressure developed either by a motor driven pump, or compressed air. This is needed to atomise the fuel so the combustion is clean. Too low pressure gives a dribbly output from the nozzle. The burn would be a bang-bang set up, as the minimum output will be around 10kW (lots of heat, more suited to a foundry if burnt continuously). It would also need an electric supply of around 250W. So you'd need some of the WVO to run the generator. In this case use all the WVO to run a generator and duct the heat from the generator to make use of it.

For vapourisers, the oil is usually drip fed into a burner, and would usually be thinner than WVO (ie vapourising oil). To get clean combustion, the air must match the fuel. This means you need tight control of the oil supply, and a stable flue draught. The vapouriser can burn continuously and has a rough output of around 2 to 4kW. There is some lattitude in the air/fuel mix, but this is obtained by the oil burning with a high temperature part in the burner to vapourise the oil (hence the name).

I haven't done anything trying to burn oil in a rocket stove, because wood is so much more convenient as a fuel, and I suspect oil would cause more trouble than I need. Also when TSHTF, any oil will be useful for making other products.

G'Day Roy,

I dunno how my math is, but my vapouriser burns approximately 3 litres of WMO/Hr at full throttle and according to my calculations that is about 28KW of output. I used the values WMO = 31,868BTU/Lt (145,000BTU/Imp Gallon) *3 = 95,604 BTU/Hr divided by 3,413 BTUs per KWh = 28.011 KW/h. Allowing for a guestimated 40% inefficiency that still give me a healthy 16.8 KW of usable output.

My heater is sufficient to keep our 17 square stone walled home comfortable at about half throttle in our mild winters, with day temps of about approx 8degC (46degF)

I'd agree with those figures Spike, I use 10kWh/litre for oil fuels as it would only be lab measurements that would tell you in more detail. People would never notice in their homes. Your heater is much higher output than most vapourisers in the UK, which are usually used for cookers. We also have significant building regs etc in the UK, so unless he has special approval, Allister's workshop stove would probably raise some eyebrows.

Did you see the PM I sent?

its easy either way. the problem is a fuel air mix and that can be worked out with observation. only difficulty is the fuel oil feed and just like other liquid fuel stoves this can be adjusted with a valve. try it and see how it works what i cant see is why you would use oil when it has better uses in other applications. Life forms like easy energy so use it to feed chickens or something. Wood falls off trees and is easy to get; if you are in a place with no tree's then its worth the try.

Definitely agree about using wood for fuel. It may take some effort to collect and store it, but most people spend their "busy" lives in front of the TV so some exercise would be useful. Not so easy for those i high rise blocks perhaps.

I have a few novel ides in that arena.

Roy Clarke wrote:I'd agree with those figures Spike, I use 10kWh/litre for oil fuels as it would only be lab measurements that would tell you in more detail. People would never notice in their homes. Your heater is much higher output than most vapourisers in the UK, which are usually used for cookers. We also have significant building regs etc in the UK, so unless he has special approval, Allister's workshop stove would probably raise some eyebrows.

Did you see the PM I sent?

Hello Roy, I had missed the PM as I wasn't looking I guess.

So far I haven't worried about a catalyser as the heater burns nice and clean and fuel is plentiful and free,... plus I don't like tempting fate, working on the heater in our living room. As clean as it operates there is always a small amount of fluffy light soot on the interior of the firebox and i think I could be rid of that if i was forcing the burn rate a little higher. I found out about this once when I lit it in the morning and got distracted and forgot to turn the fuel down as it heated up and became less viscous. The result half an hour later was a heater that was literally red hot. When I isolated the fuel and it cooled down I noticed that the inside was as clean as a whistle. My main worry was that I may have ruined my pyrometer which has an upper limit of 1300 deg.C, it was pegged hard against the stop. Fortunately it seems not to have suffered at all.

I don't know how Allister got around the regulations, but it was in use for several years at least. (He has now retired)

It is possible to burn a mixture of water and oil(makes a very hot fire) see SAS Survival Handbook by John Wiseman or perhaps GOOGLE

Google up "military immersion water heater" They were gas/diesel powered rocket-ish stoves meant to make hot water in 35 gallon trash cans for field kitchens. They run fine on filtered WVO, as long as the WVO is hot.

There should be a way to set up a venturi to "pull" the oil into the burn chamber, something knocked up from pipe fittings to set in the edge of the feed tube.

I ran an oil dripper on a pocket rocket (BIG one-55 gallon drum) that was sunk in my stock tank. When the rocket was running hard, the oil drop would burst into flame before it reached the bottom of the feed tube.

I haven't done this, but I saw a forum for biodiesel makers somewhere and it would appear that the process leaves a combustible byproduct other than the diesel itself. common practice for people who make the stuff seems to be that you soak this byproduct (which is a liquid) into paper briquettes and then burn them.
Judging by the mixed reviews of paper briquettes they probably need all the help they can get- maybe these two 'inferior' fuels can mitigate each other's weaknesses ?

Hello people, I´m Celio from Brazil and I think I found a way to burn oil without smoke (or minimum smoke).
Well, just to remember current status:
1- many people found a way to a simple burning to produce light with wvo without smoke, it looks that it´s difficult to find the calibrate the oxigen, wick and smoke, but in small scare (just to rpoduce light is easy, putting some burning cotton (wick) in the oil - example: http://worldwideflood.org/ark/technology/oil_lamps.htm

2- to use in stove (more heat), many people tried but it produces smoke (example: rocket stove oil fueled idea http://youtu.be/b8KO60kSyJ0). The smoke is produced by incomplete oil burn, and so people tried sofisticated ideas using pressured air ou pressured oil (like this http://youtu.be/AHlwiUqu5Qc)

So, my new idea: the exposed WVO produces smoke, but to produce a complete hot burn, you needn´t pressured oil/air if you find a equilibrium (like in oil lamps). To find this equilibrium is difficult, but I had an idea: collect the excess of oil so it doesn´t produce smoke. If you collect the excess of oil, the burning area is like burning solid fuel like wood (and wood does not produce smoke in rocket stove).

See the pictures: I made a tube where the oil go to burning area (well, I made a tube thinking in it like a artificial woodstock), and the how the excess of oil is difficult to manage to burn it all, I made a hole so it falls in a can (and you may take this can to put in the tube again). result: no smoke. Why? In other systems (like in rocket stove oil fueled idea) the excess of oil fall into the stove´s floor and produces smoke. How in my system the excess fall into a can, it doesn´t burn (incomplete burn) and no smoke.

My next goal is make it in a bit larger scale, because the flame I get is bigger than in oils lamps but is not enough to cook.

I know this is an old(ish) post but I've been thinking about this too. So I tried it yesterday. I tried soaking the wood in the oil first then burned the wood (as was mentioned earlier in this post) and it burnt quite well but was messy in general. Than I had a brain wave and hung a can inside the top of the riser with oil in it and made a small hole expecting it to drip into the reburn halfway up the riser, vapourise then itself burn, no go. The can just burnt to a crisp. Then I tried cutting the bottom 25mm off a small bean tin and 2/3 filled it with wvo and slid it into the bottom (air intake) section of my "L" shaped rocket stove. I'd already started the fire going with wood and got it nice and hot to help with the re-burn. I pushed the can to the end of the tube where the ashes from the wood fall down. The heat from the burning wood pretty much makes the oil boil/vapourise and the fire just above it sets fire to the oil in the can. The fast air flow into the pipe draws the flame up the riser where its re-burnt and it produced very little smoke but a lot more heat which can be seen from the amount of heat haze coming out of the top of the riser.
Soooo... what I was thinking, what I need to do is make a smaller narrower container to hold the oilwhich would be half covered to stop the oil burning all at once and would allow oil to be constantly fed into it without the risk of it vapourising before being fed into the burning tray. I know it may seem complicated so I'll try and draw a pic of wat I mean.
I did notice that my mobile rmh got MUCH, MUCH HOTTER and stayed hot for a lot longer, but that was burning the 2 types of fuel at the same time, the wood created the heat which helped to vapourise the oil. I didn't use as much wood to gain the extra heat as the oil was doing the extra work.
Regards Neil