Simplest Burner ever.

Space Heating with SVO WVO Vegetable Oil Biofuel.

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Simplest Burner ever.

Postby David » Tue Dec 01, 2009 5:00 pm

I have been mucking around with a theroy I have had for a while and believe I have come up with the simplest burner ever although the principal I have since seen in other designs.

When Oil is heated enough, it will change to vapor and that's what burns.
The benifit of this obvious fact is that it does not need to be sprayed through air or pressure but rather only has to be heated or contact a hot surface.

The problem with heating Veg oil in a coil or similar design is when it boils off, it leaves behind substantial deposits which quickly block any tube it is contained and heated therein.
What is required is a more open design where these deposits can be burn to ash and removed or blown away.

The burner design I came up with is nothing more than a straight piece of 2" exhaust type pipe with a 3/8 line entering from the outside. Forced air is blown in with the aid of an old reversed vacuum cleaner. Any fan could do but the more air the more fuel can be burned.

I set up a number of bricks in my wood fire Pizza oven so the end of the burner was somewhat enclosed and the heat and flame would be contained to a degree so the bricks would always be at a high temperature. I had some bricks at the side , bottom and top of the burner tube with solid bricks at the back and the ones with holes further forward. the holed bricks will allow the flame to escape and heat themselves very nicely in the process.

To start the burner off I connected the 3/8 line to a gas bottle, started the vac and opened the gas valve with a piece of burning paper at the burner end till it lit and I got a nice flame. It dosen't take long for the bricks to get to a red heat and then I shut off the gas and connected another line to a drum of veg oil hanging overhead to give a gravity feed. I have also successfully started the thing off with a tin of diesel with a piece of newspaper in it and just initially using the blower and I have also started it off with a wood fire to get the initial heat.

The oil feed drum must be high enough to prevent any backpressure from the vac stopping of pushing back the oil. I cat the 3/8 line at an angle and reversed it from the flow to stop the air blowing into it and hopefully also set up a bit of a venturi effect that may or may not negate some of the air pressure.

As soon at the oil was blown onto the hot bricks it self ignited and the oil flow was controlled from there to give a clean flame. In reality I found it better to run the oil fairly rich ( and smokey) initially to get the bricks as hot as possible. The hotter everything is, the better and cleaner it will burn.

In an enclosed are that would retain the heat such as a wood stove, the refractory lining would also help create a heated atmosphere that would assist the oil burning. Initially the oil control can be a bit finicky but once the bricks are glowing well, the fire stabilizes and can easily be left alone.

The heat this simple burning setup produces is quite amazing. My pizza oven weighs about 1000Kg and internally is 3 ft deep by 2 ft wide. I had the ENTIRE interior glowing red hot in a bit over 30 min. The heat output as I said is regulated by the amount of air and therefore fuel you can burn but the old vac I was using is only 250W so there is plenty of room to up the output. I think I was using about 12.5L hr so I was generating about 430,000BTU at that rate.

The thing with this burner is its simplicity. The only thing it really requires is a source of air which could be a vac as I used or anything in between a proper centrifugal forge blower or ventilator down to a 12V bilge blower for a boat or off a car.
There are no pumps, nozzles, compressors or anything else other than a bit of tube, some steel (or copper) line and a source of gravity fed WVO.

I have tried some Diesel and Bio mixed in with the Wvo and it does help the startup phase of the cycle as these fuels light off noticeably easier than the straight WVO but once everything is up to heat, there is no difference in the way the burning occurs.

Some things I found so far:
The oil should enter from the top of the burner tube. This seems to make it disperse better in the airstream and noticably better burning in the heat up phase can be seen than if the tube is rotated and the oil is coming from the bottom.

The oil should enter from the end of the tube where the air is admitted. This stops the oil in the tube being exposed to the heat in the burning chamber and allows the burner tube to be heated from the fire and help vaporise the oil before it gets to the bricks.

Using Bricks ( or ceramic) is far better than using steel as the heat retaining medium as steel used in this application will burn through with amazing speed. If you have a supply of small 1/2" steel plates you could swap out, by all means use them but I found they burn far quicker than I would have imagined.
The heat I have created is so intense it actually has melted and glazed the bricks to a very noticeable extent and the point of the oil burning is easy to spot by the glazed and eroded area on the plain bricks.
They will continue to glow red for more than 45 minutes after the burner is shut off.

I have observed the oil in 3 stages exiting from the burner tube.
Pure vapor ( smoke) which catches immediately.
a spray of oil which burns as soon as it hits the hot bricks and,
a flow of oil out the bottom of the tube which will dribble out and burn either in a puddle or when it contacts the bottom of the bricks.
For the most part the 3 stages exist simultaneously but when the combustion area was really hot, the the dribbling stage disappeared.
It dose not appear to effect clean combustion when it is occurring though.

This burner is bit of a brute force type and I think is best suited to large heating jobs that require longer burn times rather than frequent startup and shutdown. It would be perfect for heating large amounts of oil, swimming pools and large sheds.
It could be scaled down and maybe use a catalytic converter off a car instead of bricks and a much smaller air and oil delivery which is something I'll try when I can find an old cat off a car.

As far as simplicity goes however, its about as simple and cheap to construct as I have ever seen but delivers massive clean heat.
_____________________

I don't give a damn about what might or could happen until a significant group of people can tell me it HAS happened to them.
Until then, it's just more endless gloom and doom Veg folk law.
David
 
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Location: Sydney Australia

Postby SunWizard » Tue Dec 01, 2009 7:57 pm

Nice description. Got any pics? It sounds much like the drip burner I have been using in my woodstove for 2 winters, described in another thread here:
Simple VO drip into woodstove works good
Last edited by SunWizard on Fri Sep 24, 2010 11:35 am, edited 1 time in total.
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Postby harry3 » Wed Dec 02, 2009 4:09 pm

Sounds good David, what does the smoke look like comming out the chiminy?
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Postby David » Wed Dec 02, 2009 6:38 pm

SunWizard wrote:Nice description. Got any pics? It sounds much like the drip burner I have been using in my woodstove for 2 winters, described in another thread here:
Simple VO drip into woodstove works good


I have read volumes about those burners, seen heaps of pics descriptions and I still can't get it in my head how they actually operate and what principle they use. :oops:

Perhaps the method of operation is similar but the practicality and construction is worlds apart. The idea i am using needs basically no construction, just put a small pipe feeding into a large one and arrange some bricks with cement or anything else... although You could certainly affix them together.

Once everything is up to heat and the fuel ratio adjusted correctly, there is no smoke at all. There is some at startup when I run the thing purposefully rich to speed up heating the bricks but once they are up to heat, nothing but the smell of warm air comes out.

I used this the other day as I had guests coming over for home made Pizza and couldn't use wood to heat the oven as there was a fire ban. Reading up on the provisions of what was and wasn't allowed, I saw it was basically solid fuel that could emanate sparks that was banned and gas and electric BBQ's were allowed.
AS I live in the middle of suburbia and more than complied with all the other regulations ( including not only having access to a garden hose but in fact a Fire pump feeding from a swimming pool) I used the oil burner and had no problem.

I was watchful of the smoke but it was no more than a gas BBQ would generate and less once the thing got to heat in about 10 min. The heat generated was so intense, I turned the burner off and left the oven for an hour before I started cooking and found the temp initially was still a fraction hot.

Ultimately my grandiose plan is to use a brute burner like this in an old gas boiler and use it to heat my swimming pool. If I can do that, the next small step would be to use the pool as a giant heat sink so I can fire the boiler maybe as infrequently as once a week and just pump the water through radiators in the house.

It would be impractical to try to get any of my burner ideas to a state where they could be left totally unsupervised so my idea is to have a big heat sink where I can run the burner when I am around to supervise and have heat in reserve I can take off when the burner is shut down.
This way the worst that can happen is I get a water leak under the house where it would not matter a bit anyway.
_____________________

I don't give a damn about what might or could happen until a significant group of people can tell me it HAS happened to them.
Until then, it's just more endless gloom and doom Veg folk law.
David
 
Posts: 333
Joined: Thu Mar 06, 2008 4:12 am
Location: Sydney Australia

Re: Simplest Burner ever.

Postby coachgeo » Tue Nov 08, 2011 11:50 am

Never got pictures of this ...... no pics means it didnt happen :shock: :mrgreen:
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