The best of the best burners!

I put about 10 psi on the fuel tank so that the flow rate to the burner does not fluctuate with the level of fuel in the tank, and also to give better control with the needle valve.

I have no idea what CFM the leaf blower runs at on low.

I use a standard shop vac hose from the blower to the burner, and a PVC valve at the top on a Y so I can start the burner without combustion air, and then slowly close the valve and ramp up the combustion air slowly (over about 10 seconds) so I don't blow out the flame.
Its a bit of a Rube-Goldberg looking affair, but it works well.
I light it once, fine tune it via the needle valve, and never have to touch it again for the duration of the melt.

If you turn the blower up a notch, the fuel mixture becomes too lean, and so the fuel flow would have to be increased to more than 3 gal/hr.
I have found that using more than 3 gal/hr with my size furnace seems to run cooler, and less than about 2.5 gal/hr with proportionally less combustion air also seems to run cooler.

 

Where am ultimately going with this... have you ever thought to pressurize your oil using a pressurized syphon From the psi from the blower?

By the way I love your Camp out picture! You do have a lot going on there.

 

I am not sure I understand the question exactly, but I have tried various methods to get a drip-style burner to atomize sufficiently via various swirl vanes in the air stream of the blower, but I could not get it to atomize enough to be useful.

The propane tank is actually my pressurized diesel tank.
One pressure regulator converts the incoming air pressure to 30 psi for the siphon nozzle.
The other pressure regulator supplies 10 psi to the fuel tank, and it has a 30 psi safety valve on it.

Edit:
The pressure inside the furnace is probably a few psi, and this is from the leaf blower.
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As I said, where I’m going with this is, would if you pressurized your diesel tank from your blower. This would maintain a constant pressure regardless of level if it is a syphon. No compressor compressed air would be needed if pressure from your air pump was sufficient.

Edit; how much psi do you add to your fuel tank? How do you keep this constant besides the 30 psi bleeder valve.

 

If there is only 4 types of burners... or mix there of...
One, is the glumpy.... with a external burn chamber...With a lot of forced air.
Second, is the drip...With a lot of forced air.
Third, is siphon nozzle with air compressor… With a lot of forced air.
Fourth, is pressurized fuel…With a lot of forced air.

They all have one thing in common. A lot of forced air.

Can this forced air have enough pressure to compensate for a pneumatic compressor???Pressurizing the fuel vessel, Adding enough pressure to keep fuel moving and adding a lot of forced air?

 

The old man that lives next to me blows he driveway with one of those toros... Loud like sucker! I like my nuke fan, nice and quiet. Tis true OMM, I run the fan flat out and tune the fuel to suit the cfm's. What they are, I have no clue. I would say enough and for me. If it wasn't, I'd find something that blew a little harder and then up the fuel flow. Thanks for the kind comments about my videos. It all started because some guys wanted to see how I did it. If you watch the first one, I'm half hammered by the end of it. I knocked off 2 bottles of red wine while playing with silicone.

Measuring CFM's accurately is actually not that easy. When I do it to a home system, I have to run the heat, find the supply temp, return temp and know factory rated btu's. It's simple math from there, but it's not like our homemade burners come with BTU ratings so it's a wag at the end of the day. Makes my head hurt and I've been battling weather all night, so I'm pretty fried tonight.
Once I have a good guess what the cfm's are, it's pretty easy to diagnose and say maybe it's a dirty coil, or restriction somewhere. Funny thing really, without the use of heat, there isn't a good way to do it. I've gotten some strange looks when it's 100 outside and I'm turning on someone's heat full blast.

 

I find it interesting that Pat feels his furnace will not run hotter with more fuel than 3 gph. That may be from lack of combustion space.

I have the cheap Walmart leaf blower and use it on low through a shop vac hose. We all tune our furnaces by the amount of flame out the top. The engineering to design the blower and fuel system is far in excess of that required to just hook up a blower and spit some oil into a hot box.

Pat uses a dump valve to bypass his air to atmosphere. That works. For any blower I prefer to stall it as that is less load on the blower so I have a knife gate in my burner tube to positively adjust the air making it to the furnace. Some large blowers become unstable at stall and some become unstable at no load. Leaf blowers are stable from free flow to stall so there is no issue which way you control it.

My blower has two speeds, brass and iron. I can melt iron on the low speed but it's faster if it's on high and I'm outing more oil in. I don't want a pressurized firebox because I want more air and fuel in so long as it has adequate space and time to burn. Very tiny combustion spaces seem counterproductive to me. If you have a hard refractory lining and are wanting to limit mass to heat up adding 10% to the diameter adds 10% to the mass but combustion volume goes up by the square.

Thought about your pressurizing the fuel tank with combustion air. If you stall your blower partially (valve in air supply to furnace) you can raise the blower discharge slightly. If you are using a drip burner that may give you an advantage. Elevating the fuel tank, even by a foot above the drip nozzle contributes as well so doing both may work well. You would want to have well filtered fuel in your fuel tank. I use tank pressure to push fuel through a filter. I can just dump screened waste oil into my tank. I can tell when the filter is plugging because I have to open my needle valve more. If you don't pressurize your tank you do yourself a favor by having a large fuel line with smooth flow path, not a lot of elbows. You need your needle valve pinched a bit in order to maintain control. Otherwise small changes in temperature of the fuel line may cause swings in fuel flow. Control requires pressure drop across the control valve in order to negate other minor pressure fluctuations. I think using the blower to pressurize the fuel tank has some merit so long as you have excess blower capacity. If you need to operate the blower with no restriction into the furnace to get the air you want then you will have lost the pressure advantage of using blower air to pressurize the fuel tank. It's easy to set up a clear tube manometer with fuel in it to see just how much boost you are getting in inches of fuel. If you get 10" boost it may be much simpler to raise the tank ten inches.

 

The only way I know to create enough force to atomize fuel using the blower (in a fashion that equates to atomization achieved by compressed air) is to have some sort of spinning vane arrangement that shears the liquid.
I don't want any moving parts in my burner, so I prefer a mechanical approach to atomization, ie: either by using compressed air at 30 psi to a siphon nozzle burner, or a gear pump to a pressure nozzle.

The leaf blower is a low pressure/high volume air pump.
Compressed air fed to a siphon nozzle is a high pressure/low volume application.

The siphon nozzle and pressure nozzle use the energy in the compressed air or in the pressurized fluid to break up the fuel into droplets.

My observations of the drip style burner is that it is a poor atomizer, and basically it eject slugs/drips of fuel into the furnace, which then breaks up, flashes and burners, but in a fashion that is far less even and less uniform than a siphon or pressure nozzle would provide.

The drip style and siphon/pressure nozzle burners both have the same function, but I think the siphon/pressure nozzles are much more stable and uniform in their operation, and that is why I prefer using them over a drip-style burner.
As I stated I never have to adjust my burner once it is started and initially fine tuned.

Others have talked about the added complexity of a siphon/pressure nozzle, but for me it is well worth the added complexity to get such an even and consistent burn, and I consider the added complexity minor.
If you use diesel and a fuel filter, you will not have problems with a siphon/pressure nozzle.
If you use gloppy waste oil, you will most likely have problems with a siphon/pressure nozzle.

Edit:
I call my siphon nozzle burner a "plug-and-play" unit, since with a pressurized fuel tank, you can turn it on, make the initial adjustment, and it will run perfectly without needing adjustment for as long as you feed fuel to it.
I expect the pressure nozzle burner to be the same way.
I highly value plug-and-play in a burner.
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Would the solution be an adjustable exhaust hole? Say start with a 6 or 7inch hole and then cast some mizzou collars that can sit in the hole to choke it down as necessary? Any combustion chamber is just an air pump, more air/fuel you can get in and out in a given time, the hotter it will get.

 

I has been a while since I ran the valve tree with the burner, but that is how I got to the 3 gal/hr setting.
The valve tree was set up for 1,2,3,4,5,6,7,8,9 and 10 gal/hr, and so I tried every flow rate with my new furnace.

All the tests were run at night, and the 2.5 to 3.0 gal/hr range seemed to run the hottest.
It was not a scientifically measured thing, but rather observing the intensity of the furnace and chimney glow at the various settings.
And having arrived at the optimal 3 gal/hr setting, it turns out that everyone else who does iron seems to be operating at about the same fuel flow rate, which somewhat reinforces the idea that this is a pretty optimum setting for the typical furnace size that we use.

I think it has to do with the surface area inside the furnace, and the fact that a given surface area can only optimally burn X amount of fuel.
Any more or less fuel seems to visually operate cooler.

Here are some of the tests, including two hot-restarts.
You can see the heat in the furnace vary as I dialed in the various fuel flow rates.

Edit:
I did not vary the combustion air during these tests, but I have tried that previously, and more than 3 gal/hr of combustion air and fuel seem to cool the furnace.


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UMM!!! Isnt time a factor , the energy needs time to transfer to the melt , or basically you are just blowing energy out the top of the Furnace , Wastefully??? this theory would make a Larger, but well insulated Furnace more efficient the a smaller furnace.

V/r HT1

 

Crucible furnaces are notoriously inefficient for melting metal, and the efficiency is in the 7-19% range (per some data I found on the internet).
It does seem that high combustion air and fuel flows just push their way through the furnace without having time to mix and combust in an optimal fashion, and you can see that by how big the flame is coming out the lid; ie: the mixture does not really start to combust well until it exits the furnace lid opening.

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Im going to throw this down Note MIFCO is using DUEL Burners with a 150 CFM blower

GUYS it looks like we are moving air through our furnaces way too Fast

PART No. 900015 – MODEL B-301 WITH No. 4UV SAFETY

Stationary crucible furnace, capacity No. 30 crucible, for melting aluminum and copper alloys, plus class 25 to 30 grey iron in limited quantities. Furnace lining and lid are high alumina, air rammed sections, backed with refractory insulation. Chamber size 13″ diameter x 15″ deep, with dual tangent burners and lid exhaust opening. Attainable combustion chamber temperatures to 2400° F, nominal 750,000 BTU with two valve mixer to use either natural or bottled gas. Complete with No. 1610 Industrial Turbo Blower, 150 CFM, 12 oz. with 1HP, 3600 RPM, ball bearing, drip-proof motor. Available in 120/240 volt, single phase or 240/480 volt, three phase. Furnished with silicon carbide crucible rest block. No. 4UV ultra violet combustion safeguard system, consisting of an automatic spark ignition with blower air switch and continuous flame monitoring. Provides furnace shutdown in event of air blower failure, flame or power failure. Wiring conforms to the National Electric Code. Electrical components are UL and CSA listed. Approximate shipping weight 920 pounds. (Specify voltage and phase when ordering).


V/r HT1


P.S. any one know what the 12 oz is in reference to the blower???

 

That will be 12 oz of water head. High pressure for a blower.

Pat: I very well remember your tests. I am not questioning what you found, just find it interesting and wonder what the driving factors are. I also remember the article you found on introducing turbulence in the flame (in my opinion, just like a drip burner provides).

HT1: If you are getting complete combustion within your furnace you are not pushing too much air through. Remember MIFCO says you need to turn the burners down when aluminum melts else it will be blown out the top. I don't think anybody here is blowing their furnace that hard. maybe I'm wrong. My leaf blower is 160 cfm advertised on high and I run it on low, supposedly 130 cfm and I'm probably getting 100 cfm through the furnace. My chamber is roughly their size.

 

I wish I could offer a more definitive/scientific reason why it works at 3 gal/hr and low on the Toro leaf blower, but I can only speculate.
But I can say is that it does work well, and I am happy to have stumbled across these settings.

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This is a thought from the uneducated masses and should be treated as such!
In the future I will be using a siphon nozzle with the fuel pressurized at 9 P.S.I. The pressure for the fuel is produced by a small electric automotive fuel pump. The fuel reaching the nozzle is controlled by a needle valve and the compressor is a small 1/6 Hp 15 P.S.I. Air brush compressor.
It works very well at atomizing the fuel however with such a limited amount of compressed air as the amount of fuel increases the droplet size increases proportionally. From a very fine air float mist at 1 G.P.M. to a rather heavy almost like light rain at 6 G.P.M. I plan on using this small continuous rated compressor so I do not have to use a multi Hp. Garage style compressor.
On the drip burner. I think those that are having problems are over thinking this a bit while others are thinking just drip it in and it will burn.
I through an emergency burner together in 15 minutes. It was my first and only drip burner. It worked perfectly the first time and started with an oil soaked old T shirt / rag.
The reason I think I had such good luck was. I used 1/8 inch steel break line for the feed tube. The burner sat deep in the tawnier not fat from the burn chamber si I mounted the tube to the inside of the burner pipe against the steel pipe to help preheat the oil and only puled the tube away from the side wall at the last possible point. I then made sure the end of the tube was cantered at a right angle to the burner main tube. The break line was cut at 45 degrees and the edge was polished sharp so the hot oil would have to attempt to form on the sharp edge of the break line edge and be shattered by the air rushing by.
A very short story made long. It worked and worked well!.
Joe

 

Joe: Since your drip burner worked well, why are you going to a siphon burner?

I wouldn't swap my drip burner for anything which might plug up.

 

Some people can't resist complicating things. I fire up the drip burner and melt a pot of bronze in less than twenty minutes in an un-insulated furnace. What more could I ask for? To use less fuel? The stuff I use is free.

Richard

 

It is sort of like the early carburetors, like the one used on the Wright Flyer.
It was an evaporative type carb using a heated surface (as I recall), and it worked.
But you won't see the Wright carb used on a modern vehicle because it does not give the necessary precise control.

If a drip-style burner gives you the control you want, then there is no need to get any more complex.
After I used a siphon nozzle and then tried to go back to a drip-style, there was no way I was going to give up my precise siphon nozzle control.

You can always try the drip style first since it is simple to build, and if you like it, then go with that style.

The only person I know who went from a siphon nozzle back to a drip-style (sort of a drip style, he uses an Ursutz which has a fuel drip into it) is Clarke.
If Clarke had tried a gear pumped burner, he may still use that type, since he uses clean diesel anyway and there are no issues with poor fuel quality.

Seems like the waste oil users tend to go drip, and the diesel users tend to go siphon nozzle.

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Exactly.. Lets say in the span of one minute, you burn 5ounces of oil compared to a quart of oil. Naturally, the one capable of burning a quart is going to be a hotter.