antique hobby steam trains

Mike T., Swampeast MO

Closest thing I can find is once sentence from an issues of the "Ideal Fitter":

"One square foot of active heating surface will evaporate from 3 to 6 pounds of water per hour, from and at 212 degrees Fahrenheit."

A statement from "Heating Design and Practice":

"A boiler horsepower is sometimes designated in terms of heating surface, 1 horsepower being considered the equal of 10 square feet. Althis this view enables us to compare boilers on the basis of heating surface being provided, itis no measure whatever of the steaming capacity of the boiler. We should buy boilers on the basis of pounds per hour output under the conditions of pressure and feed-water temperature that will exist and under which the boiler must operate".

Since it takes about 970 BTUs to turn one pound of 212F water into one pound of 212F steam, it would follow that one square foot or heating surface would provide from about 2,900 to 5,800 btus/hr <I>under these conditions</I>.

2 square meters = about 21.5 square feet, so it would follow that 21.5 square feet of heating area could provide from 62,000 - 124,000 btus/hr (or about 24 - 48 horsepower) <I>under the stated conditions</I>.

Operation at 150 psi would almost certainly change things considerably. Didn't the real locomatives use some sort of staged piston arrangement to allow reasonably efficient recovery of the energy in steam at such high pressure? I was under the impression that a simple single stage piston arrangement is not well suited for high pressure steam.

Glen

amazing bunch of hobbyists!

And a local fellow makes various models from scratch. According to the boiler code I can use up to 2 square meters of heating surface area - thats a big boiler! (in terms of model trains) So at 150 psi - how many btus per sq meter is that??? Reason I ask - he is redesigning a scale 6 4 6 for oil power - bio in particular. I am just thinking of firing rate and where to start with this project.

Mike T., Swampeast MO

Steam at 150 psi is nothing to toy with.

Derheatmeister

One of my toy's is a "Dampf Machine" (Mini Steam engine) I've Learned alot while Playing with it.and once in a Blue Moon i "Steam it up". Really Cool Stuff them Engines....HM

Roland_12

\"Dampf Machine\"

I have a Wilesco WLS - D24 Steam Engine. Haven't fired it up in 20 years. I don't know if the fuel is still any good. I remember it was great fun to run. Made really cool mechanical sounds. I think I'll pull it out of the cellar and oil it up. Ahhh memories! Roland Schmitt

Mike T., Swampeast MO

Have an steam engine like that myself. It operates at about 15-20 psi and had an overtemp safety system.

Frankly, I'd consider a working model railroad engine utilizing 150 psi steam to be a true locomotive and more of a potential bomb than a toy.

What sort of scale does the model maker want to use? I hope not something of the sort large enough that a child or other passenger could ride in a car...

Glen

let me assure you -

that the term "toy" is not characteristic of these beasts. These busters work - hard! Fully engineered and S stamped with annual hydros. I am developing a staged/modulating firing bio oil system for this manufacturer. Shop tests will be done in this next few weeks. Most are in the 5 - 10 bohp range. This one is a bit larger. But back to my question - 2 square meters of firetube equates to what firing range??? Or are you going to make me fiddle about in the shop??

:-)

Derheatmeister

Roland, that's the one still lot's of fun after 30 years. the fuel:WWW.mpioutdoors.com or Esbit i think . HM.

Jim_64

Glen:

I checked through all of my old reference books and the only mention of "area" is that of the burner grate. I could not find a single mention of actual heat exchanger area nor could I find any "rule of thumb" regarding the relationship of burner grate to heat exhanger area.

Glen

me too

which is why I asked - even the older CE books list grate size, bed thickness etc - all for coal. And I have been looking at info relative to bohp vs sq ft of heating area too.

Roland_12

Live Steam

Hi Glen, Sorry I can't answer your question but after a breif Google search, I realized how trully complicated the subject is. Perhaps you could contact (by e-mail) some live steam organizations. There are scads of them in Britain,Europe and Australia. There are also many steam hobbyists in the U.S. as well.

Mike T., Swampeast MO

In a later edition of the "Ideal Fitter" I found ratings for steam, fire-tube, oil-fired boilers that include "actual boiler heating surface sq. ft."

At least for these boilers (both within models of the same diamter and among models of different diamters) the relationship between area and output is almost perfectly linear. Of course the output of these boilers could be changed significantly by varying the oil consumption rate. VERY important to note that increasing the firing rate (oil consumption) does not result in less than 1-1 fuel vs. output ratio. In other words, the more you increase the firing rate, the lower the efficiency of the boiler.

At the lowest (most efficient) firing rate, 1 square foot of actual boiler heating surface equates with about 3,000 btu/hr.

This means that 2 sq. meters would be good for about 65 mbh worth of steam operating a radiator under standard conditions at the lowest suitable firing rate. A doubling of the firing rate increases output by about 90%.

The minimum firing rate would appear to be about 0.20 pounds of fuel oil per hour per square foot of heating surface with the maximum firing rate about 0.46 pounds of fuel oil per hour.

Provided the model is somewhat similar to these old fire-tube boilers, I believe this will give you a decent starting place for determing the amount of power available as well as the fuel requirement.

This seems to jive pretty well with the other estimate based on 3-6 pounds of steam from 1 sq. ft. of heating surface area.

I'm far from a steam expert and I'm unsure how things will be affected by operating at 150 psi. My guess though is that your required firing rate will be somewhat higher and efficiency somewhat less.

Seriously again--let the model maker know that 150 psi steam is dangerous in any quantity. A small leak will be invisible and quite capable of cutting (not to mentioned burning) exposed flesh.

I like to watch my pressure canner wiggle on the stove when operating at only 12 psi. The sounds coming from it let anyone know that there's a LOT of power inside...

Glen

you would be amazed

at the sophistication of the train, its boiler and steamways and the authenticity under which its built. If a client orders a scale Hudson then thats what he gets - right down to the scale insignia on the front. These folks know all about steam - and these are open systems (no cond return). 150 is the max pressure while norm op is 125. Mike - your numbers jive with what the oldtimers tell me, their experience strictly seat of the pants stuff. Their numbers a bit higher but would account for efficiency losses and pickup. This is all about control of pressure and the ability to handle a full train (30 - 40 people plus engine/tender) on grade. They have some neat competetions too. Look at this site - http://www.masonstrains.com/index.htm

Al Corelli_2

Steam engine

I have one of those somewhere. Has an electric element under the boiler.

I think it needed a gasket for the glas end on the boiler.

Gonna look for it today.

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Mike T., Swampeast MO

Do they actually feed more water into the boiler as the steam is used? Or are they like the little models I'm familiar with where you simply add water and fuel once and use quantity of fuel insufficient to run the boiler dry?

[Deleted User]

The REAL thing....

I spotted this unit (one of two being constructed) at a local boiler manufacturers. These are for use at a local place called Tiny Town that has a minature steam railroad.

They are both ASME rated vessels.

ALso included a picture of the largest steam engine surviving in North America. It has since been moved and rebuilt and resides at a local transportation museum (Forney). I've heard that they fire it up and run it between Denver and Cheyenne Wyoming once a year, just because they can...

Enjoy!

ME

[Deleted User]

I suspect...

a more controllable fuel source, like LP or oil...

The last thing you want to do is run out of steam pulling a load on a grade. No steam, no go, and possibly no brakes ;-( YEE HAW, backwards at 60 MPH...

ME

Mike T., Swampeast MO

The pellets I feed my model steam engine are highly controlled with regard to their energy output and the instructions regarding how many to use and how much water to add very specific.

With a known quantity of water (and no return feed) combined with a fixed amount of fuel the potential for danger is slight.

While I love to experiment and don't have too much problem with potential danger, I respect the power of steam enough not to vary from specific instruction for a highly engineered and very simple model that has been available for decades.