Turbulators on propane boiler

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BillF
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Re: Turbulators on propane boiler

Post by BillF »

Bill,
I find the 80% of heat transfer in the firebox plausible, if you are burning coal, because radiative transfer will be a major effect. If you are burning propane, I think that radiative transfer has to be a far smaller effect. Most of the difference is due to the density of material that will be emitting thermal radiation: coal is a dense, solid material which is an excellent approximation to a "black body." The propane flame contains far less hot material, and those combustion products only absorb (and thus emit) over narrow and well-separated spectral bands.
Therefore, I would expect that most of the heat transfer in a propane-burning boiler has to occur by direct conduction across the heated surfaces. If that is the case, the fraction of heat transfer through the firebox versus thrrough the boiler tubes ought to be close to the ratios of the areas of those surfaces, and the use of turbulators will have a larger impact.

- BillF
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NP317
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Re: Turbulators on propane boiler

Post by NP317 »

The design of the propane burners also makes a difference in the radiance of energy to the firebox.
I have different burner designs in my two locomotives, and am in the process of learning which design seems more fuel efficient.
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Bill Shields
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Re: Turbulators on propane boiler

Post by Bill Shields »

Agreed...with an arch and properly installed burners and controlled airflow..I wold be hard pressed to think other than 80% from the firebox.
Too many things going on to bother listing them.
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Chris Hollands
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Re: Turbulators on propane boiler

Post by Chris Hollands »

This is a little off the subject to a degree -
My brother worked at thermal power station in the control room back in Australia it was about 1000MW .
They use to change fuels quite often between coal ,oil and propane /LNG I remember he use to say that when they ran LNG they use to have a lot of issues with high temps in the upper areas of the boiler tubes and exhaust , the heat carried a lot more than other fuels and they had to watch this constantly .
So it appears gas heat transfer is quite different from coal and oil and maybe the same in our engines ???
little giant
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Re: Turbulators on propane boiler

Post by little giant »

Sorry to get off the subject, but is the tube coil in the fire box a superheater? Also when using this type of tubulator does the blower need to be increased compared to using a twisted flat design?
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Drprez
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Re: Turbulators on propane boiler

Post by Drprez »

The tube coil in the firebox is a stainless steel super heater. Made from a brew condensing coil. Total distance in the coil is 16 linear feet in the coil which runs from the valve in the smoke box through the boiler flue to the fire box where it comes through the arch coils then back up to the smokebox to the cylinders. This is 100% super heated steam. The loco has virtually nothing visual out the stack due to the super heat. I have verified both with thermal image and physical test of the super heat. Super heated steam will light paper on fire. This is the case here. It’s important to note because it is superheated there is no water to lubricate the cylinders so a good reliable steam chest lubricator is vital to prevent any cylinder damage.

Here are some of the coil in my Chloe
Stainless coil from a brewing condenser
Stainless coil from a brewing condenser
Stainless coil in firebox & turbulators
Stainless coil in firebox & turbulators
Looking from the mud ring up
Looking from the mud ring up
You can see the burners inside before the arch was inserted
You can see the burners inside before the arch was inserted
I originally used twisted stainless skewers in the tubes which performed well. Then I started using this design which as noted above propane transfers heat by heated surfaces. Because the huge increase of surface area touching the boiler from the wire design I see a 100% or more increase in startup time. What took 30 minutes takes less than 14 min to get to running pressure. I actually was shocked how much this improved things. It also helps when you are in motion limiting drafting loss. As well slowing the heat from leaving too fast when not in motion.

I still have turbulatos in various sizes if your looking for them. I posted the link earlier in this thread.

As far as the burners I use . This has been a process and I have been through. 8 designs to find the burners that produce the most heat and best overall distribution. As well as which work best for at the station and also for in motion. I found many woukd have issues once moving since propane moves with the wind literally.
Burner layout
Burner layout
Thr best design I found was using similar to the Marty burner. However I purchase my burners from co2 generators. The co2 generator for green houses use a perfect rosebud flame that never separates. They have air intakes at the base and a removable tip crown. I get them from TItan CO2 Generator company and they run 4 for $20.
CO2 rosebud burner by Titan CO2
CO2 rosebud burner by Titan CO2
Last edited by Drprez on Wed Sep 14, 2022 5:26 am, edited 1 time in total.
Nicholas Kalair
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Drprez
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Re: Turbulators on propane boiler

Post by Drprez »

For the blower I use less now then before. In fact I built a new blower ring with only 3 tiny 55 bit size holes which are more than enough for even the biggest draft. I should note here that my blower ring does NOT use superheated steam. It uses wet steam off the turret which has its own intake inside the steam dome. You need wet steam on the ring so the water vapor draws air out with it.

Rebuild of blower
Blower 3 holes
Blower 3 holes
For my little American with the small fire box of 4 inches x 6 inches all these improvements with out a doubt increased my performance. I can now pull 4 cars with 2 passengers up a 2% grade no problem. Before I could only pull me on the tender at ZERO grade.

I have finally found the burner layout below work best. The propane feed is in the shape of a 3 prong trident. With the input at the center. On the outer legs I have 3 burners on each side. The middle leg I have 2 burners offset from the outside ones. I have a brass sheet that sits on top of the air intakes with about 1/8 clearance around each burner and seals flat on the mud ring. This helps limit the draft well as improve the heat retention in the firebox.

Burner sheet
Brass sheet
Brass sheet
Burners from under the American (the tips are not on in this pic)
Burners from under the American (the tips are not on in this pic)
It’s important to note my burner flames DO NOT touch the walls of the firebox. If they do they quench the flame resulting in an incomplete burn and often the smell of unburnt hydrocarbons out the stack. WHICH IS DANGEROUS AND EXPLOSIVE. From the center of each burner to the wall is about 1.25”. That is perfect when at full fuel flow the tips are just short of the walls and fill in the center of the fire box completely. The center 2 burners are about 1:4” lower than the outside burners. Allowing the complete burn of fuel in the firebox.

What I also thinks help a lot is my arch design. I came up with this because I was trying to retain heat for the super heater. My arch looks like a letter F sorta where the bottom horizontal line is where the hair escapes out to the tube this maximizes the heat exchange inside the firebox. Keeping the hottest air in the firebox right where the super heater is at.
Arch and super heater
Arch and super heater
Arch design
Arch design
I will post some more thermal images showing this soon .
Nicholas Kalair
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Drprez
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Re: Turbulators on propane boiler

Post by Drprez »

Here are the burners for my Chloe which has a larger fire Box then the American so I was able to add more burners to the layour. But still using the same concept as in the American layout drawing above.
Full flame burners perfect layout!
Full flame burners perfect layout!
Chloe burner design layout.
Chloe burner design layout.
Here is a pic from behind my American. You can see the only open side is along the back . You can also see the air intakes on the burners.
American burner box attached to mud ring
American burner box attached to mud ring
American burner with brass plate
American burner with brass plate
Side view of brass plate resting on intakes
Side view of brass plate resting on intakes
After doing all of these improvements I can’t even begin to tell you how much more efficient my little 3 gallon American runs.

In both the America and in the Chloe I use an axel pump so I rain coils of the water supply in the smokebox to preheat the water . This was fantastic also resulting in almost no power loss when adding water.
Water supply coil in smoke box
Water supply coil in smoke box
I have both an axle pump and injector on the locomotive. The axle pump supply goes through the smokebox. The injector supply is cold from the tender to the injector then to the boiler. With the smaller boilers on these 2 locomotives I have found the axle pump much more efficient way to supply water when I’m in motion. When I’m stopped the injector works well.
Nicholas Kalair
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Bill Shields
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Re: Turbulators on propane boiler

Post by Bill Shields »

Good to see people experimenting
Too many things going on to bother listing them.
Odyknuck
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Re: Turbulators on propane boiler

Post by Odyknuck »

I just went to the Titan website and it appears they now want $16.45 each for their burners?
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Bill Shields
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Re: Turbulators on propane boiler

Post by Bill Shields »

That's cheap...seen the price of brass lately?

If your steam is TRULY superheated, your slide valves are in for a heap of hurt.

Have you put a thermocouple into the steam chest to confirm?
Too many things going on to bother listing them.
Berkman
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Re: Turbulators on propane boiler

Post by Berkman »

I too would be interested in the effect of the superheating on the slide valves.

How do you install/remove the superheater coil? I'm guessing this is strictly a boiler off exercise.

I guess also the firebox is pretty full when you have the arch and superheater installed.

Would be really interesting to see the difference with the same arrangement installed on something much larger like a 1.6 USRA mikado etc, which has a much larger firefox and piston valves.
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