Aliexpress waste oil burner atomizers?

Discussion in 'Burners and their construction' started by Dazz, Dec 17, 2019.

  1. Dazz

    Dazz Copper

    Hi
    I am about to start down the path of building an iron foundry.

    Has anyone considered using the Aliexpress waste oil burners? They are available with electric start, swirlers.

    Nozzles are available 1.0mm to 2.5mm. What would work for a metal furnace?

    Dazz
     
  2. Petee716

    Petee716 Silver Banner Member

    A picture of what you have in mind would help. Aliexpress is a big place.

    Pete
     
  3. rocco

    rocco Silver

    Google "Aliexpress waste oil burner" and you'll find lots of them. Here's one of them:
    Aliexpress nozzle.jpg
     
  4. Dazz

    Dazz Copper

    Hi
    Aliexpress is like e-bay. Specific listings disappear. As above, a search will reveal a number of options.

    Dazz
     
  5. Jason

    Jason Gold Banner Member

    Most of us here build our own or go with the delavan/hago rigs. I'm sure that's all that ali burner is. Another knockoff.
    It's not rocket science to build a siphon burner. Here's mine. You can build it standing in the aisle of homedepot in about 20mins.
     
  6. rocco

    rocco Silver

    Along with the nozzles, they sell these too, for $5, I don't think I could be bothered to build one.
    vortex generator.jpg

    And for $35, nozzle, fitting, turbulator and ignitor

    burner assembly.jpg
     
    Last edited: Dec 17, 2019
  7. Melterskelter

    Melterskelter Silver

    The Hago Siphon Burner in a nominal size of about .75 to 1 gallon per hour and run at about 2.5 gallons per hour is a proven and inexpensive solution to the burner problem. I burn diesel in mine as it is the simplest and easiest fuel for me to use. Some folks burn waste oil but seem to need to do a little extra work in terms of filtering and heating the waste oils. I have found it important to be meticulous about final filtering even "clean" diesel and I also filter the compressed air used for atomization. It can be done without filtering either the fuel or air, but filtering decreases problems. Much has been written on this and other forums concerning burner construction. Reviewing those threads is probably worth the time.

    I have also found it very helpful to measure fuel flow, though I do not think anyone else here does so. FWIW http://forums.thehomefoundry.org/in...with-a-pelton-sensor-and-digital-readout.811/

    Denis
     
    Mark's castings likes this.
  8. Jason

    Jason Gold Banner Member

    I bet Hago is PISSED! Their stuff is not cheap.
     
  9. rocco

    rocco Silver

    BTW, Myfordboy's latest video (Dec 7th) shows him building a foundry burner with one of these cheap Chinese nozzles.
     
  10. Petee716

    Petee716 Silver Banner Member

    So which option were you asking about? The one Rocco posted in post#3 will work.

    Pete
     
  11. rocco

    rocco Silver

    FWIW, the nozzle used in this video is a 1.0mm.
     
  12. Dazz

    Dazz Copper

    Hi
    The other thing I need is a blower. Again there are lots to choose from on Aliexpress.
    Like these ones:
    Blower Fan

    How many watts is recommended?

    Dazz
     
  13. Melterskelter

    Melterskelter Silver

    If you use a siphon burner (and any other burner so far as I know), the key is to not blow too much air into the furnace. I use a low-end repurposed 18v leaf blower shuttered to reduce its output by about 50%. One of the common newbie errors is to think they need to blast a huge amount of fuel and air into the furnace. This results in a cold furnace as the fuel air mix has not adequately combusted prior to exiting the furnace.

    Denis
     
  14. Dazz

    Dazz Copper

    Hi
    My thinking is that a bouncy castle blower would be ideal. High volume, low pressure, quiet and cheap.
    I think a 250W fan should be plenty big enough, but I don't know.
     
  15. rocco

    rocco Silver

    I did a little bit of math and it definitely supports that statement. By my math to completely burn diesel at a rate of 1 U.S. gal per hour takes about 22 cfm of air although realistically you'd probably need a blower that rated at 2 or 3 times that to compensate for the back pressure of the whole furnace assembly even so, that's not a lot of air.

    BTW, if anyone wants to double check my math, here are the numbers I used: weight of air 0.0807 lb/cuft, stoichiometric ratio of diesel 14.5:1, specific gravity of diesel 0.88.
     
    Last edited: Dec 20, 2019
  16. Another factor to consider when burning oil: the "flame propagation speed" which is drastically slower in fuel oils than for gases such as hydrogen or propane. Hydrogen gas is the fastest with a speed of 1.5 Metres/second for stoichiometric ratios, methane is 0.4 M/sec, all measured with laminar flames. You can bet the speed of fuel oil is much slower and you run the risk of unburnt fuel exiting the furnace. This is why a low volume of air into the furnace gives hotter temperatures when burning oil (longer dwell times) and why propane can be burnt at higher airflow rates than oil (burns faster than oil). So to ensure complete oil combustion in the furnace chamber you need: higher temps, higher compression and increased turbulence. Turbulence increases the flame propagation speed, i.e. a candle flame (laminar) vs a blowtorch flame (turbulent) so by directing your flame back at the fuel spray, it helps by boosting temps, vaporizing the oil spray, increased pyrolysis and adding turbulence.

    So for an oil fired furnace you can increase the burn rate by having a design that swirls the flame round the chamber and directs flames back at the fuel spray. This is why diesel engines have swirl chambers built into the cylinder head or in the piston crown: increased turbulence combined with higher pressures and temperatures lets the fuel burn at speeds of around 10-20 cm/second in the engine. So even with high pressures, high temperatures, plenty of turbulence and a super fine spray of atomized fuel found inside an engine, diesel burns ten times slower than hydrogen at room temperature and pressure.
     
    Last edited: Dec 21, 2019
    Clay likes this.
  17. Jason

    Jason Gold Banner Member

    That's the LAST blower you want to consider. It's WAYYY too much. Start with something MUCH smaller. Microwave blower motor or old small canister vacuum. Draft blower from a home furnace... If you run a bouncy house blower, you will have to dump 90% of the air off it. I have one, I tried it and it was a bust. Peek my channel and look for part 4 of bronze casting. It's a pretty old video, but watch the first 10minutes. It's a tour of my siphon burner the kwiky. It's basically what you are planning. You are OKAY with running compressed air I take it???
    I have a 60 gallon compressor and use 20psi of air to move the fuel. The compressor runs once every 8-10 minutes and then only for about a minute or two.
     
  18. Dazz

    Dazz Copper

    Hi
    22cfm converts to 0.6m3.
    The 750W fan pushes out 7m3 so definitely over sized.
    I don't have any spare fans about the place so Aliexpress is my go to for a suitable fan.
     
  19. Jason

    Jason Gold Banner Member

  20. Melterskelter

    Melterskelter Silver

    The way I try to tell if my fuel/air mix is optimal is a method I learned here and on AlloyAve. I look for a hint of smoke in the exhaust and place a piece of unsooted steel (usually one of my skimmers) in the exhaust stream. It should show some sooting after 10 seconds or so. If there is no soot, I cut back the air a bit or up the fuel. As the furnace heats up, it burns more efficiently so the air needs to be trimmed back 5 or 10 percent(estimated). One other clue to a good hot furnace is that unshielded skin on my face should get very uncomfortably hot as I open the furnace and check slag.

    Incidentally, the soot on the skimmer has a side benefit of causing the slag and iron to stick to the skimmer much less. So, popping it off the skimmer is done much more easily with a hammer. Took me a year to learn that bit.

    Denis
     

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