Oil burnner

[roddy]

I finally bit the bullet and bought a used locomotive. A 7.5 Mich-Cal Shay. It is currently set up as an oil burner. The boiler/firebox is an 8 inch diameter tube and the bottom/grate is covered in fire cement. It does not have enough air; the fire door must be left open to even run the burner. The only air is supplied by 8 3/8 inch tubes about 2 inches long all on one side (the same as burner. The bottom of the grate is covered by a brass plate. I know I need to add air. Should I replace the fire cement and how much air and where should I let it in. All of the way around or what?

Thanks Roddy

[bcody]

Does your engine have a normal firebox with the oil burner mounted at the front, firing back toward the firing door?

If this is the case I would suggest you open a rectangular hole in the floor of the firebox, about 1x3", just in front of the backhead. The idea is to direct the fire back toward the firing door, add supplemental combustion air and then direct the flame forward to the fire tubes. If possible you should strive for a flame path of approximately 18" prior to entering the fire tubes. You want all combustion to be complete prior to the products of combustion entering the fire tubes. If your flame path is too short unburned fuel will enter the fire tubes and cool off and be deposited as soot in the fire tubes. Some would suggest installing an arch but I have never felt the need to do so.

I have burned oil in two 1/8th scale locomotives and four full size steamboats with excellent results in all cases.


Bill

[roddy]

The boiler is a T type 8 inch vertical tube. 6 inch horizontal
13 inches bottom to crown sheet
About 7 inches to the bottom tube.
Burner is located at rear and slightly off to one side.
The burner is located in a ring about 2 inches deep.
The burner could be rotated any direction with some new piping.

[bcody]

Roddy:

Difficult to troubleshoot via long distance but here goes.

From what you say you have a circular firebox, 8" in diameter with the burner inserted on a tangent. I think the idea is to create a circular fire path. Is there a lip at the top of the fire ring? If yes, I would consider opening an air inlet at the center of the bottom and close off the 3/8" diameter tubes. It seems like it is a situation where you have to play with it to get the desired results. Any other oil fired boilers like yours in the area?

I think I would be making a test firebox. You know, an 8" diameter tube by about a foot high. Mount the burner on a tangent and start playing with air intakes. BTW - are you using a steam injection burner? Oil by its very nature is a semi flamable fluid and must be atomized or vaporized before it will burn correctly. You can put a match out by plunging it into a can of oil. Try that with an oil vapor and BOOM. That is why when you suck out an oil fire you turn off the fuel and let the firebox clear, then introduce an ignition source and then turn the oil back on. Even then you sometimes get a BOOM as the fire re-lights.

Bill

[Fred_V]

Roddy, can you take any pic's looking in the fire door? pic's always help.

[bcody]

Had another thought.

Are you supplying draft? Must have draft to get circulation through the boiler.


Bill

[Curtis_F]

Roddy,

About 80% of your air flow needs to enter the firebox around the burner to ensure enough oxygen for good combustion. The rest should be from a lower firepan damper and sometimes a firedoor damper as well.

See attached drawing for what I'd recommended for a general layout.


Cheers,

Curtis F.

[makinsmoke]

Bill has a good point.

Does it perform better while running, or is the draft problem mostly while sitting?

You have to run a blower while the engine is still to help the draft.

When running the exhaust from the cylinders aids the draft.

Next relevant question. Does the fire get sucked out as soon as you open the throttle?

Brian

[Harlock]

Everyone here has very good advice. To add to that, when you bought the locomotive, did the previous owner show you how to fire it? Did he have any problems with it? Was it known to work before?

Oil burners can be tricky at first to get the hang of, but once you do figure out what each input is doing, everything makes easy sense.

To start it, give it an external source of draft and atomizer air. (shop air) - is there an external air connection with a three way valve on the plumbing, to switch between steam and outside air?

Once you have air supplied to the system, Turn on the blower a little, turn on the atomizer a little (sorry, it's all done by sound and feel, I can't tell you what "a little" is without being there, but try just cracking everything at first) put a propane torch in the fire door pointed down, light it, then open the firing valve slowly until it catches and makes a dull roar. Depending on the burner type and geometry, there may also be a thumping noise, which is normal. (fuel burning in pulses as it comes out)

Adjust the firing valve until the stack is a very light haze or just clear. Too much fuel and you have black smoke (partially burt or unburnt fuel) and too little fuel and it will go out. With a good burner you can run the stack clear without it going out too easily.

The atomizer can be adjusted within a range, and that is done by sound. You want a muffled roar, not a super loud roar. Too much atomizer can also put the fire out, or will give you an unnecessarily big fire. To little atomizer will result in incomplete combustion and low temperatures. For learning purposes, if you open the fire door and look as you adjust, you can see in general what's going on. (although it will change as soon as you close the fire door)

Once you've got steam pressure you can switch over to steam. The thing to keep in mind is that as the pressure in your boiler goes up and down, the atomizer and blower will change with it, so you need to keep an eye on things and adjust as necessary. Otherwise as the steam pressure increases, so does the atomizer and blower pressure, and it will suck the fire right out if left unattended.

When opening the throttle, you want to simultaneously open the firing valve to give it more fuel. The blower should be turned down to almost nothing at this point. The exhaust draft is taking place of the blower and will vary widely depending on throttle position. Running an oil burner is a two-handed operation....throttle opens, more fire. Throttle closed, less fire. Keep the stack to a light haze or clear. When first starting to move, a light haze is good to ensure it doesn't go out, then clean the stack up once you are at speed. The draft is much more inconsistent at low speeds, with less frequent, more powerful chuffs trying to suck the fire out. Although with a Shay it's quite different. It's more consistent due to the higher tempo of exhaust with the lower gearing.

If you've tried dirtying up the stack a lot when starting, and you have proper atomizer settings and it still sucks out, then yes you may have a need for more secondary air.

I've run some engines that are so touchy that you have to be right on top of the firing valve with every change in throttle. I've also run engines that are so benign that you can leave the fire at one setting and run all the way around a track and just pull the throttle handle. (a little engines pacific has been the best one for that so far)

Firing a live steamer is in some ways harder than full size, because you are the fireman and the engineer. So the amount of attention you give to the fire is necessarily compromised, so it won't be as perfect as having a dedicated fireman. A little smoke here and there is OK.

this would make a good video tutorial...excuse to go to the MG&W and fire up the Mogul.

-M

[Harlock]

One other thought. If it was known to run well before and is not now, you may have a clog in the burner supply line. Blow air back up into it, or disassemble and clean.

[Mike Walsh]

I need to take photos of the addition that we put in WF&P #928 to relieve the firing issues that engineers were encountering. Everyone was encountering flame-outs - these happened from slight changes in throttle, or just trying to fine tune the oil supply, etc etc. One of our members decided to play around with a bit of steel and came up with a 3" pipe with some cross drilled holes (some pattern I believe), and that helped, but did not solve the problem. He decided to get some 1" pipe and cross drill a bunch of holes in, and made a 7-tube cluster (2, 3, 2) all welded up, and put that in the 3" dia pipe. Interestingly enough, this helped a lot! I've yanked the throttle from 0-100%, with the engine SLIPPING, the fire at 2psi atomizer, and the fuel supply nearly shut off. I don't think it went out. In addition to the improved firing, the entire hunk of metal also allows someone to flash the fire off the pipe as long as you don't wait too long (15sec, maybe). If you do wait longer, you can light a wick/fuel-soaked rag off the metal! I've done this and it's quite interesting and you don't have to hunt around for a lighter. For one reason or another, our lighters seem to grow feet and walk away from the oil burners....

-Mike

[Harlock]

I need to take photos of the addition that we put in WF&P #928 to relieve the firing issues that engineers were encountering. Everyone was encountering flame-outs - these happened from slight changes in throttle, or just trying to fine tune the oil supply, etc etc. One of our members decided to play around with a bit of steel and came up with a 3" pipe with some cross drilled holes (some pattern I believe), and that helped, but did not solve the problem. He decided to get some 1" pipe and cross drill a bunch of holes in, and made a 7-tube cluster (2, 3, 2) all welded up, and put that in the 3" dia pipe. Interestingly enough, this helped a lot! I've yanked the throttle from 0-100%, with the engine SLIPPING, the fire at 2psi atomizer, and the fuel supply nearly shut off. I don't think it went out. In addition to the improved firing, the entire hunk of metal also allows someone to flash the fire off the pipe as long as you don't wait too long (15sec, maybe). If you do wait longer, you can light a wick/fuel-soaked rag off the metal! I've done this and it's quite interesting and you don't have to hunt around for a lighter. For one reason or another, our lighters seem to grow feet and walk away from the oil burners....

-Mike

Would very much like to see this pipe and where it is installed.

-M