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Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 04:59am 09 Jun 2020
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I have built a LOT of oil burners over the years ( although not too many recently) but they have all been in the multi Hundred KW range. My " small" ones do 200 Kw and the biggest to date puts out over 1100 Kw. Built one a few weeks ago I haven't fired yet that I'm aiming for a Minimum of 2000Kw and hopefully if I can get enough air into the thing ( fuel won't be a problem, I Might get 3000 Kw or above.
I fired up an old burner the other day for the first time since I have been here. Used a jumping castle blower and a car fuel pump to push the fuel in fast enough. The thing howls like a jet engine afterburner and is starting to get near supersonic.You can hear the thing just shredding the air. I did that once before with another setup and got a Mach Diamond which was pretty unexpected but got the Vid showing it. Neighbours Really got a new insight to the nutter living next door as if all the solar wasn't enough. I wish I could get hold of a Blower that did a couple of PSI. Could really do some damage with that!
I am wanting to make something to heat the house using waste veg oil and want something to do about 10Kwh. 500Kw burner is easy, I was thinking about a 5Kw burner but gave up on that idea as just too hard. 1L an hour is about the best I think I'll get without too much trouble. I want to use the burner to heat a ( previously) gas fired water heater I have removed the burner from. On gas it does a bit over 5 Kwh input but I think there may be a bit of margin on that but hard to say what the limitations are.
Normally all my burners are forced air and I was thinking to use a small 12V bilge blower for the little burner but that still seemed a bit over kill. I was going through all the variations in my head and pulled out a note book I wrote my hair brained ideas in and re discovered my "L " Burner design.
This would be a draft type burner and I could pull the heat through the gas water heater as they have a flue/ HE right up the middle which I could add to for more draft if needed.
I have trouble getting things small in my mind so I got a bit of 75mm Sq Tube, cut a wedge out with the plasma cutter to bend it to a Right angle L shape and MIG'ed it back together closing off the open end on the horizontal Burner section. There is a primary air hole in the top of the horizontal leg and cut some holes with the plasma in the upright section for secondary air. Couple of wide legs for stability and a bit of 4" pipe about 1.5M long for a flue for testing purposes. Very simple.
Put in a bit of oil and some diesel soaked paper towel, lit it and off it went no trouble. First thing is in this config it puts out a LOT more heat than 10 Kw. maybe something 30-40mm would do 10 Kw but that would be tiny and hard to imagine working at all. Concept would be the same so spose it would.
I can take the 3/4" Primary air hole down to about 1/2" which seems to be the sweet spot as it's set up now. Running the thing flat out it roars, smokes a bit from lack of secondary air and glows red the first 45Cm up the flue. The heat radiated is very good for an outdoor heater.
I brought it down on the back verandah last night and set it up after the first burn and the thing throws good heat for that application. Mrs came out and had a look and then brought out the stew she made for dinner and we sat on the verandah and ate dinner by the fire. Amazing how nice the most simple of pleasures can be. This does roar a little but nothing like a force fed burner even on lw hear. If the chimney was fully ducted above the roof line, it would be very much quieter.
I'm feeding the thing with a Pulse pump because although everyone wants simple with gravity feed, it's more of a pain in the arse and inconsistent for long burns than what it is worth. Oil tank warms up and oil changes viscosity, level in tank drops, oil layers out.... You have to adjust the things constantly. Pulse pump, same volume every time and you can set the timing and it will do the same output all day.... or night. I'll put this on a simple timer or an arduino to pulse the pump for say a second every 15 or whatever seconds to get the output to as close to it as I want.
The output will change once I put the water heater on the thing as it has a smaller diameter through the middle and I expect cooling the output will also diminish the draft. Might be good this is a bit over built.
I haven't measured the KW output on this but it can easily do 10kw and I suspect maybe 40-50. Definitely could do more with some extra secondary air holes and maybe a larger primary air inlet. If this was in a garage it would certainly put out good heat especial with a fan blowing on the back to pull more heat from it by creating a greater temp Differential with the surrounding air. The addition of something like an old 9 Kg gas Cylinder on top of the burner itself which I will look at for the verandah heater, would also increase surface area and more energy could be bled from it. I'll do a reverse internal flue for that so the heat is made to move around not just go straight up and out.
I have some larger tube up the back and the mrs now wants me to build one of these for the Verandah. I'm thinking I can up size the thing a bit to 100mm tube and put it in a 44 gallon drum as a back reflector and blow the bilge fan from the back to push more warm air forward. With a bigger tube the thing would also give a useful area as a heating surface and could have a kettle sitting on it or even cook on the thing.
I'm in about 17 Minds as to how I might do this home oil burning heater but this is a first idea I want to explore. This one is pretty much a more constant burn with a water reserve to store energy for the Night and morning without letting the burner run all the time. I could also do a more powerful conventional burner and get a couple of 400L electric water heaters as storage and heat them in batch mode and use the stored heat. I can also make up a Tube in tube HE and use that with the draft burner and just blow air through that and duct it into the house. Easier and simpler but no storage of heat unless I run a wet back as well and all the plumbing which means I may as well stick with the water system.
I have also got a spa recently and the heater in that takes all day literally to heat the 2000L of water that holds so I'll be doing a Veg oil heater for that anyway of at least 100Kw to get the thing warm in a reasonable time. Might be easier to heat that in batch mode and use the heat from that for the house as well. Even just a 40o temp difference ( Don't think I can go too hot without damaging the shell in the spa) will give about 90Kwh although I don't think the insulation on the spa is great on the bottom even if it does have a thick cover. Then again, Free fuel, efficiency is not particularly Critical.
I have done a draft burner before years ago using an old cooking pot and a lid which worked well but this one I am particularly impressed with. Was simple and quick to build and has Miles of potential in various applications. The other thing I thought of was "J" Burner. Bit of ( round) tube bent to form a J shape and put oil in the bottom and let the draft work on that. Could be done in 3" exhaust pipe and bent up by a muffler shop in one piece. Drill some secondary holes and that's it. Might have to do a YT vid on that for all the non hands on people. :0)
Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1022
Posted: 09:21am 09 Jul 2020
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What sort of pules pump are you using? I was thinking about one of those pumps from a coffee machine, I have repaired 2 of them mostly the hose blows off, last time that happened, water come out of it everywhere knocked out the safety switch. Anyway they pump good pressure but not sure how long they last, guess it doesn't matter if they can be found on a roadside pickup.
I did use some of those old type kero burners that had heating coils in front of the main jet, once they go hot and enough pressure was available they work really well.
Just thinking if the heating coils were used in the L shape burner it could draw a lot more air in and be quite ferocious.
I have made my own charcoal and gas for various things and use the charcoal in this little L shape contraption, it has a small grate inside and typically had a 12v fan at the front, easily melted down a heap of aluminium cans. Should be able to get a hot clean burn with oil, for a water heater.
Some large fish farms have air blowers that do pump some air pressure, some are around 3Hp or so. Mostly they seem to be much like the vacuum cleaner impellers, probably much bigger, perhaps a small multistage vacuum cleaner scrounged from somewhere might make enough pressure to assist the burn.
Read it again, your using a care fuel pump, they work well. Edited 2020-07-09 19:24 by RevlacCheers Aaron Off The Grid
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 10:29am 09 Jul 2020
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It's a Pulse pump similar to the Coffee machine type only a lot bigger and I think lower pressure. It's 12V where most of the coffee machine ones are 240V.
Yeah, I have made a few of them but they won't run on waste oil, Veg or Engine. The tubes Foul up in no time with the residue waste oils leave. Fine On Diesel, Kero, Turps, Biodiesel or if one has far larger gonads than I do ( or a death wish) can run them on petrol as refined fuels don't leave residue or ash.
Be Ok like I said for Diesel etc but I think you would hit a limit anyway. I modified my Burner with some extra secondary air holes and the thing fairly Rips now. I put the hot water heater on the thing and it did work OK but the smaller diamater of the flue through the heater did slow it down to pretty much spot on 5 Kw.... My target output.... which I now believe is too low. 10 would be about where I want to be.
I'm thinking to make my own heater buy welding a large pipe through the middle of an old car gas tank .... or 2 end one end. If I could put a 4-6" pipe through the center, I could get a fair heat through the thing. This would be good for heatup and I could then throttle the thing back by damping the flue.
I haven't done much with wood/ Charcoal but it has plenty of heat although the energy content is low compared to liquid fuels and you need a lott of wood/ Char and it burns away Quick.
With Forced air oil Burners I have melted about everything non exotic From Ally to copper and steel and even brick. Yeah, I didn't even know you could melt a brick until I did it and it became a problem with my over powered burners. 30 Kw is a LOT in a home sized furnace, throwing 200Kw+ was a little overkill.
You'll need to add secondary air holes and a good length flue.
They are called Channel Blowers and will do up to 1.5 PSI. You don't need anything that expensive though.... and they are NOT cheap. I use Jumping castle Blowers on my big burners and they will easily supply up to 1000Kw of air capacity depending on the actual Blower. Most are 400-600W but the opening and the impeller size is the key though. I have a very old blower that was used to Power a Church organ. That thing blows some pressure although not as much volume as the Jumpy Blowers.
600Kw is a walk in the park for the jumping caste Types. You are going to need a pump that will move 1L a minute of oil to keep up with that.
You only need pressure as far as moving the air down a tube and out the burner. Anything with an impeller rather than a fan will do it... even a hair dryer. I have a 12 V Bilge blower from a boat that cost $20 New and that will do 50Kw+ standing on it's head.
One thing I have found is to make the air feed pipe at least as big as the outlet of the blower which is obvious but what can escape one is to make the outlet of the burner BIGGER. The air is heated and expands... like the principal of an engine, Piston or Jet. To get the most air through and therefore heat, you have to remove any restrictions and that is to the end of the chain be that the burner or the ultimat outlet and everything between.
Also having larger outlets slows gas speed. If you are melting metal direct, you don't want the molten metal spraying around. A larger outlet reduces the thrust which is not what you want in a heater either as it reduces the time the hot gas can give up it's heat to the surrounding surface area of the heat exchanger, whatever that is.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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