After looking at the frighting pics of the inside of the boiler, recent topic here, being a naive here, some questions;

Can someone(s) explain the aspect ratio of the various firebox's to boiler I have seen. Some have a very deep firebox drop while others don't. Is this a fuel issue like oil vs coal or wood or is this more to a lower crown sheet position inside a boiler. Boilers for relatively flat lines vs ones for steeper grade like in a Shay.

Finding a 2 foot gauge steam is rather hard and I know what ever we do wind up with, when ever vs the pre 1945 diesels on the slow boat here, what ever it is will get a totally re-manufactured boiler, but that is another story.

Tnks

The NP Yellow Stones had about the biggest firebox on a locomotive (144 square feet I think) because they burned crap grade coal. If you are burning anthracite a broad shallow fire was best. Most of the steam generation is around the firebox. The rest of the boiler is just a feed water heater for the firebox. Boiler generating capacity has to match cylinder demand. How many strokes per minet at what cutoff for how long.

I wonder of any of the Polish / Chinese 60Cm 0-8-0's are still available? They are relatively modern and - your mileage may vary - may be perfectly serviceable without heavy overhaul. Not sure why you plan to replace a boiler not proven faulty on a locomotive you haven't even located yet.... good luck hunting. Several German tank engines were brought over here back in the 1970's or thereabouts for tourist lines. I think there's a good candidate sitting on top of a pole in Arkansas if memory serves.

If you're interested in one of the Chinese versions of the 0-8-0, check out the link below. A group in Wales bought one from China (believed to possibly be the last one manufactured) and have converted it to 2-foot gauge and are overhauling a lot of the appliances on it. I'm sure they would be glad to answer your questions, but there is a plethora of information on their web site.

http://c2project.org/

Actually we have been looking at several different ones out there for the past year. Naturally the usual suspects from the dealers and even from a few museums. The running gear is not the expense, its boiler work and for our short remaining lives I do not want a 4-5 year restoration.

For us in southern california I have been told, due to fire hazard in our area and for air quality control NO coal or wood. ? ? That leaves what ever will have to run on tractor diesel ( no road tax ), harder to get but available ship heavy diesel. I have the BTU tables for the various fuels including hard and soft coal. BUT my plan as of now is to run on used engine oil. The Hawaiian " sugar cane train " steam, now for sale but that is another story, were converted to run on used engine oil. Relatively cheap and a higher BTU than fuel oil. Another reason I was wondering about fire box design. Even used engine oil is now regulated in California. Before we used it as scrap to keep down dust and build up old agricultural roads, I grew up living on oiled roads.

So far of the 3 euro 600mm aka 2 foot locos we've checked out, the boilers had standing water in the smoke box taking out all of that, fire box metal was chard and the boilers had long standing water in them. From that alone, its obvious when rebuilt little would be saved. As of now we have locate 2 prospects and slowly haggling on. Not on the market the owners don't want it out they are negotiating. One is 2 foot original and one is 3 foot original but I have looked at the running gear and actually to convert to 2 foot is quite doable. I don't want to spend 4-5 years on a restoration from scratch. The diesel locos came from a museum in the EU and they said not to make any immediate disclosures they sold, later OK. Of the two I am looking at, one was original operating pressure at 125 ( really low ! ) and the other was original at 165 .

So yea, we have been out beating the brush and it's not cheap out there. Thanks to the forum members her for great info.

Right, that was one idea we kicked about. I think there was a youtube video on these guys when they went to China to pick out the one they purchased. I would consider having the Chinese to do a rebuild of the whole loco and then when it arrived, do a rebuild again to correct sloppy work and what not you know they would do.

I've worked in the Philippines since the 1980's and was lucky enough to make friends with several of the sugar cane plantations when they still had steam. Many times they let me run and play engineer. Those were really totally wore out, in fact a friend of mine has a stripped Baldwin over there he offered to give me but what is left is salt rust and all the goodies have been stripped off. Good for display but that would be about it.

China is a good possibility. The hunt is half the fun.

Speaking of Chinese narrow-gauge steam, check out this link. I don't know if they're still offering locos or not.


http://www.multipowerinternational.com/narrowsale.html

As a crude rule, the longer the 'drop' from crown to grate, the better the radiant surface and the better the developed combustion plume -- this accounts for the good performance of many 'narrow-firebox' engines, including Chapelon's converted 4-8-0s. Essential here is a properly built and proportioned arch with circulators or arch tubes incorporated -- the radiant (luminous) combustion plume travels up and back before going forward under the crown to the rear tubeplate.

A shallow but wide firebox (as with locomotives that carry the grate above driver height) has different characteristics; here you have a wider fire with shorter plume, and less draft action can carry the same mass of combustion products.

Obviously the 'best of both worlds' (at least for solid fuel and oil firing with the burner at the throat where it probably should be) is fireboxes that are both deep and wide, as in the Allegheny 2-6-6-6. In most cases this requires a supporting trailing truck under the ashpan; exceptions tend to be exotic (Garratts, Meyers, the N&W TE-1) If you have fuel that burns extensively in 'levitation' you can get decent radiant uptake in a long relatively shallow firebox (as in most Challengers); the firebox in these does NOT take advantage of the lower height and easier structure of the trailing truck.

Now a consideration that was raised in the horror-boiler thread was that lowering the crown (or changing its angle) relative to normal boiler-water height (which has to cover the tubes but never come to such a height under the dome that priming/foaming and carryover become significant -- this height being lower than most people comprehend, as the boiler water acts like boiling milk, not the old familiar 'water on a stove'). You will remember that the suggestion was to lower the crown to keep safe water level over it descending a particular grade (with the contractor's response being to adjust the water-glass details to reflect the same safety during times the water in the boiler would shift on that grade. That in my opinion was indeed the correct approach ... but there may be circumstances under which 'dropping the crown' might make sense for a particular locomotive. When you drop the crown you reduce some of the radiant uptake surface, and change the flow pattern through the firebox to the rear tubesheet.

Bear in mind that many designs, particularly older designs, treated the firebox as Stephenson did: a conveniently water-shielded place to keep the fire, not a significant part of the heat-transfer system with fourth-power efficiency in radiant uptake. As such the design may be more optimized toward convective heat transfer in the tubes and flues, and changes to the combustion space may be less critical to performance. (On the other hand, there isn't a guarantee they won't be critical...)

Deep in the back of my mind I seem to recall a proposal from Porta for a small narrow gauge industrial locomotive with a firebox circular in plan. Ring any bells with aybody?

And, there were the frames and running gear from carcasses of some 3 foot fireless thermos bottles which got absorbed into junk collections. Wonder if an are out there

THANKS Overmod, that was the information I was looking for. The mechanical why it is done. I wondered why some of the earlier steam loco's had the boiler up high with a large drop in the fire box. Other reasons naturally in the mix.

If we wind up with the coal fired loco's I am very slowly haggling over, they have to be converted over to oil fuel and I was wondering how that oil fired disbursement plate would relate to the firebox configuration.

Dan

I have a lot of information about various oil fired combustion systems - and it's not just in the firebox, but considered as a whole from the tender tank through the stack. Once you have the victim chosen, drop me the specifics and I'll help you work through it.

Dave wrote:

I have a lot of information about various oil fired combustion systems - and it's not just in the firebox, but considered as a whole from the tender tank through the stack. Once you have the victim chosen, drop me the specifics and I'll help you work through it.

Thanks Dave, because of the BTU value, we are planning on using used passenger car oil, not diesel truck as it has too much carbon, with about 10% gasoline or tractor diesel fuel. That changes the viscosity and it flows rather well. It lights quick because, for what reason I can not say, the gasoline molecules flame off and instant heat the hard to light oil. We heat our houses with firewood and sometimes wet wood. Rather than waste a lot of good kindling I use " Flame-O-Log" which is our joke name for this mix to get things going. You would be surprised how fast a 12" x 24" damp log will take off with Flame-O-Log.

At first I was surprised how much heat that mix will throw off compared to a pile of firewood.

Dan

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More carbon is better, not worse. Remember that luminous flame that just 'goes out' at the front tubesheet is your goal. The burner can be easily adapted to work with hot used diesel oil.

Have Dave shoot you the chronicles of the locomotive 112 project, which contains many details of the oil treatment and purification system you will want to adopt if burning used vehicle lubricating oil. The stuff is notorious for variable quality, often containing coolant, hydraulic oils, and brake fluid, as well as healthy dollops of schmutz. So you build an arrangement that washes it and then spins it over a carefully designed dome cyclone with strategically-calibrated gap, so the oil stays clean and the contaminants go elsewhere -- for a small engine, you run this like a bypass filter, and even a small plant will make enough clean oil in a few hours.

I'd think about converting the firebox with thermal barrier coatings as well as a cast firepan. It turns out that the Nigel Day-style centrifugal burner (with a whole bunch of carefully scaled primary-air tubes arranged like cyclone swirl in the burner pan) has not worked as well as expected -- I think the operative 'best' is still an improved Thomas type (rather than a Pritchard or Racer mechanical-type burner) and there might be some interesting details in the Dickens-Barker burner to be 'downsized' here. Perhaps for a locomotive this size 'flameholding' with broken rock in the firepan, as with the earliest versions of oil firing by the 1880s, might simplify the usual 'tetchiness' of modulating the firing valve correctly in a small furnace under what may be wildly varying load.

Typical fire tube boiler have a maximum effective length of boiler tubers was found to be in 18 to 22 foot range area. Tubes that were excessive in length were not effective in passing heat from the exhaust gases to the water on the other side. if the length of the boiler has shorter tubes not all of the heat will be transferred to the water before the exhaust gases reach the stack. That is why UP 844 tubes are 19 feet and UP 4014 are 22 feet in spite of the different locomotive lengths.

The relative height of the crown sheet in the boiler impacts a number of factors. The further away the throttle or dry pipe is from the water the dryer the steam the locomotive uses. The Larger surface area of the firebox, the larger the area exposed to the direct flame and better heat transfer. Also recognize that crown sheet typically have a 2% slope in them from the top near the tube sheet down to the other end of the firebox. So the point that the water glass needs to be set to height against is the highest point on the crown. Once the boiler is on a grade the water in the boiler will self level but the firebox will take a new orientation in the water. When climbing a hill with a cab behind locomotive running forward, the effective gradient of the crown sheet increases by the grade encountered(3%+2%=5%). When going down grade, you add 2% to the down grade to get the grade of the crown sheet(-3%+2%=-1%). If the grades and gradient changes are sever enough it can be difficult if not impossible to both keep water over the crown and out of the dry pipes. By lowering the crown sheet you allow more room for this operational demand.

A classic example of this was Uintah 50 on its early runs. To keep water out of the steam dome on that locomotive they could not see the water level in the water glass. According Uintah Railway The Gilsonite Route by Henry E. Bender Jr. they added a second steam dome and lowered the crown sheet slightly to deal with the issues.

According to the 1941 Locomotive cyclopedia, the UP 4000 series locomotives were equipped with two water glasses with a 5 inch offset to indicate the water in the boiler resulting 4 water glasses on the locomotive. The water glasses were 5 ½ inches and 10 1/2 inches above the highest point on the crown sheet. This allowed operation on grades up to 1 ½%. The water Glasses could be raised 1 inch for operation of grades up to 2.2%. Given this information we can do a calculation, with a firebox length of 235 1/32 inches a combustion chamber of 112 inches and 22 feet the length of the water space are approximately 51 feet in length. With this water space in the boiler the difference in height of water from the front of the boiler to back of the boiler on a 1.5 percent grade in the boiler water is 9.17 inches. On a 2.2% grade this is a difference of 14.44 inches.
You quickly see by these calculations that Big Boy would have operational problems on the ruling grades of many logging railroads due to the size of its boiler. A shay would never haul a freight train at 70 mph a lot of modern power would struggle with a logging railroad grade.

You can see this issue today at Grand Canyon Railway. Grand Canyon Railway has several areas where they have several 5+% gradient changes. These include between MP 1 and MP 4, topping over at station Imbleau and turning on the wye at the Grand Canyon. It is an operational challenge no matter how flat people tell you it is.

Hopefully this helps more than confuses you.

Robby Peartree

I don't think we're looking at a 60 cm gauge Big Boy here.....

What you are talking about is the difference between a vaporizing flame and a atomizing flame. Vaporizing burners are the Felix Ungers of the burner world, the old Van Boden et al atomizing burners the Oscar Madisons. That's why I was working on a way to make the waste oil clean enough to burn in a semivaporizing burner that could deal with some stuff without clogging. I don't know if the information is posted any longer, I'll try to find it and see if I can send it to you. Sulzer / SLM develoiped a vaporizing light clean oil vaporizing cluster burner for their modern rack engines that's very clean and efficient, but waste oil isn't workable in that technology. The Welsh 2 foot lines use a burner that blasts oil upwards against a curve - like a big golf tee - which spreads it out as a mist / vapor, but also uses pretty well controlled quality fuel. It also sounds like a jet engine which sort of lends a nonsteam vibe.

I'm working this weekend but will see what I can dig up next week. I had the advantage of very expert advisors like Robert, Hugh Odom, Dr Koopmans, Nigel Day, etc. and it would be great if the work we did was put to productive use.

Nice to have some fun stuff to do right now.