Prototyping a spinning cup oil burner

Discussion in 'Burners and their construction' started by Mark's castings, Feb 4, 2018.

  1. Jason

    Jason Silver Banner Member

    Yeah.. LIGHT THAT SUCKER....! Video it!
  2. PatJ

    PatJ Silver Banner Member

    We need fire !
  3. OCD

    OCD Silver Banner Member

    Burn the mother down.......

    I mean fire it up!!!
  4. I have a setup that works well enough now that I don't have roughly half the fuel in a dribbly puddle on the ground. The fuel mist exits in about a 80-100 degree curved cone the same shape as the nozzle cone on a rocket motor. Supercharging one blower with the other gave a serious boost in the air pressure and bringing the cone forward almost to the end of the stainless tube opening so the spray does not contact the tube walls is kind of cheating but it works as it will exit into the larger furnace chamber. I made a 3/4 thick plastic restrictor with a 2&1/2 inch opening: it sort of worked but was greatly improved with a 4 inch long aluminium tube glued into the opening to make the flow a bit more laminar hopefully. It runs well and both the airflow and fuel settings can be reduced and it still atomises beautifully. The water flow was reduced to the point where it was dripping out and this did cause a pulsating atomisation of the water. I shot some video and will edit it and post it soon. I'll make a steel version of the restrictor and permanently fit it to the tube opening: the current plastic unit is going to fail horribly if I tried to light that sucker up.

    Video is uploaded now, up until the 1:17 minute mark, it's running with air and water valves open wide, at the 50 second mark the water is less than half, at 1:17 it's full water and airflow shut off completely, then full water with 1/3rd air, then full water and full air again. The camera lens was misted up and in soft focus for the first half of the video.

    I'll be working all day for Wednesday-Thursday so I'll have to make the steel throat restrictor and then clear a wide area for the flame testing on Friday.

    supercharged blower.jpg

    rotary cup opening.jpg
    Last edited: Feb 12, 2018
    Jason likes this.
  5. OCD

    OCD Silver Banner Member

    Better be some flames belching out that sucker or I want a refund!!!

    I have the worst feeling that once you fire that puppy up your oil /fuel tube is going to disintegrate once the furnace temps get up there.

    Just make sure your hiding behind the thickest concrete wall in sight.

    Oh, and make sure you light 3 candles and say 3 Hail Mary's before you do light it up.
  6. Just trying to use the current unit with it's plastic restrictor is bound to end in tears!!. First few uses will have a bean can sized fuel tank until I'm satisfied with it, it'll run into a furnace so no open air "Burning Man" performance ideally. Definitely another three candle job!!! :D.

    For those that need a quick fix, I give you the Miele "Flamespin 3500 Ultra Edition"
    Last edited: Feb 12, 2018
  7. Melterskelter

    Melterskelter Silver Banner Member

    As the song says "Light em up!"

    I think you have learned all you can from water. Time to blast some oil outta that thing. Until you make that spark we're in the dark. So light em up up up!
    Last edited: Feb 12, 2018
  8. One thing about that "Flamespin" youtube video: it shows a nice hot oil vapour explosion and illustrates the need for remotely located controls away from the flames and heat. I'll shift the fuel valve or even add another one away from all the action.
  9. Tobho Mott

    Tobho Mott Silver Banner Member

    Saw the YT video you posted of testing it. So the way it's working right now it seems kind of like you have an atomizing nozzle burner (the fine mist) and a drip burner (the larger drips) all running in one tube. No wonder you need two blowers! :D Would be interesting to see it lit.

    The atomized spray cone seems really wide. Would a deeper cup maybe stretch that out a bit?

  10. I'm hoping both the drips and the spray pattern can be solved by refining the design. The bevel on the outside of the cup seems to let the water run round the cup rim before actually flying off from what the video shows so making a cup with only an internal bevel like the commercial ones should help, then the commercial units have static curved swirl turbulator blades around the cup. Another possibility is a tube nozzle that goes past the cup before narrowing a bit to curve the air over the rim of the cup a bit like a MIG welders gas nozzle.
  11. J.Vibert

    J.Vibert Silver

    Here's a thought to complicate

    Your cup is rather short in comparison to the commerical pics you posted early on. Is there any chance that a longer/deeper cup would provide the opportunity for the fuel to gain some level of velocity in the forward direction, thereby forming a tighter spray pattern...?

    As far as the bouncy castle blower pressure. What you experienced is what I have dealt with as well. Those blowers really don't overcome restriction well, but I think that's by design to be honest. They're meant to keep things inflated but not rock hard with high static pressure. I'm kinda curious how your "supercharged" arrangement will effect the blowers electrically/thermally.
  12. We'll find out soon if that's the case: I'll be replacing that cup as soon as I can to get rid of the outside bevel and deepen it a fair bit. If the outside of the cup is tapered the airflow may curve around the wide rim when air flow is restricted in a tube and narrow the fuel spray cone. There's so many factors to consider and no research lab or computer simulation to do it with. I hope the blowers have some thermal cutout arrangement, all I can do is put a hand on the plastic case and see if they get too hot. A custom built high pressure but relatively lower volume centrifugal blower is on the cards, most commercial blowers are low pressure, high volume.
  13. Made the Mk2 cup tonight: it's 25mm or an inch deep inside vs about 1/4 inch on the old cup. It has a 20 degree taper (included angle) inside and out with a 40 degree taper on the inside to chamfer the rim to a sharp edge. The cup has been shrunk fit on the shaft and has good balance, running smooth to 32K RPM. It'll be interesting to see how well it works and if the cone of the spray narrows much from the old cup. In the interests of keeping things entertaining I'll wait until I have some flame videos to post rather than another water test. :)

    Cup Mk2.jpg
    Last edited: Feb 14, 2018
  14. Jason

    Jason Silver Banner Member

    Food for thought.. I was bs'ing with OCD the other day about using a shop vac for adding suction to a project he was working on. While a shop vac may seem to be a very powerful sucking device, you would be surprised to know my 6hp machine only delivers 3" of suction. I've had girlfriends suck harder than that! The shop vac is about the same as a bouncy house blower in terms of pressure. Low PSI/suction, high volume. Again, our crappy fans haunt us. The bouncy house blower I have is just a typical squirrel cage design.

    If the redesign of the cup doesnt help this spinaminthingamijigger, then a revisit to a high air pressure source might be in order. Perhaps a big tap off a compressed air tank for test purposes...
  15. I was discussing blower selection on Sautrday and Sunday during the bronze casting session: Pete my foundry guru said there was a wide variation in vacuum cleaners, some were too weak in blow mode and others were quite good, He tried a half horsepower centrifugal blower and found it too small for his gas fired A20 crucible furnace, it worked but it was too slow for him, where an older vacuum cleaner was used for five years or more on furnace duty.

    These are photos of Pete's furnace blower, he obtained it from another foundry guy when he retired, so the unit is pretty old, probably 1960's. He tells me the motor is one Hp but in those days the motor makers used to wind one motor frame for 1 to 3 Hp and size the circuit breaker accordingly, so some brands like the old Brooks Crompton Parkinson motors were derated and could supply more than one Hp easily.
    This blower is 50mm or two inches wide and about 20-24 inches in diameter and is a high pressure, low volume unit relatively speaking. I'm fairly sure it's 1440 RPM.

    Furnace blower.jpg Furnace blower 2.jpg
    Last edited: Feb 14, 2018
  16. Melterskelter

    Melterskelter Silver Banner Member

    It is interesting to note that the blower pictured has a very large diameter to sectional thickness ratio. The impeller itself almost certainly consist of two thin discs spaced only a couple inches apart and connected by radially oriented straight vanes with an opening near the hub for incoming air. This style of rotor tends to impart higher centrifugal force to the air while sacrificing some volume. My cordless leaf blower that I use for my siphon burner combustion air is of similar design. If I were looking for higher head pressure capability in a very simple blower design, I’d be looking for this style impeller to be more likely to deliver more head pressure. I may be wrong in my assessment of this style impeller vs the more open single disc style, but my intuition suggests this is true.

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  17. J.Vibert

    J.Vibert Silver

    You're bang on Denis... Comparably speaking, bouncy castle blowers similar to Mark's are single sided and have rather shallow/tapered fins.
  18. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    If you want something that can produce a little more head, multiple stage blowers are better performers. I know I've thrown this out there before but the vacuum motor assemblies for residential central-vac installations are in expensive 3-stage centrifugal blowers that can be had for $50-$60 new. They're 13 amp 120vac and dead head at about 10"Hg in vacuum. I use them for a lot of things including vacuum assist on my lost foam rig. They have universal motors so speed control is easy if so desired. At up to 95 cfm they can supply all the combustion air I'd ever want and deliver it at high velocities compared to most blowers.


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  19. J.Vibert

    J.Vibert Silver

    Link please Kelly...

    I read your post and have been looking for a $50 central vac blower without success
  20. Al2O3

    Al2O3 Administrator Staff Member Banner Member


    The Ametek ones are hard to find for that price but if you're patient and watch eBay they can be had. I watched for a month or two and nabbed two units from a guy that was in the repair business for $90 delivered. The competing brands such as the one at the link below are plentiful, interchangeable with more or less equivalent performance. Look at the comparable auctions at the bottom of the listing at the link and search similar titles.

    It's been a couple years and looks like there has been a little price creep ($65-$69 but with free shipping). The one below has a metal horn. Some are plastic. I prefer the metal units.


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