Low voltage steam generator

Hi all, I'm a complete novice as far as electronics are concerned, but have been railroad modelling for a few years since retirement and want to move up from electric motor power to proper steam powered models but in a small scale (Not 16mm like the garden railways but around 1:32 to 1:24 scale largest). If I use conventional method of gas or meths for raising steam then I run into problems concerning indoor running as far as public displays are concerned so seeing as one manufacturer (Hornby) managed to produce a live steam Loco in OO gauge picking up power from the tracks I would like to emulate the same but have not been able to solicit how they achieved this.
Can anyone advise as to how this is done (or how it could be achieved)? Can low voltage heater elements be capable of raising steam in a boiler? or does it require a special type of generator and if so does anyone know of a UK supplier?
Regards James

you can make "steam" for visual effects (using piezo) with a reasonable amount of electrical power. Boiling water in a boiler to make "live steam" for actually pushing on pistons will take much more power than the rails (transformer) can deliver.

Why do you say that Mike? It might be too much for stock electric railroad power but you could use a higher voltage/current capable transformer to deliver plenty of power, granted you start to run some moderate risk of electrocution or fire if something shorts the tracks out. I doubt you'll find anything off the shelf for this kind of thing though.

In order to determine if it's feasible or not you need to get a working boiler using a gas setup FIRST, once you have a working gas powered boiler it's simple, determine the wattage that the flame is producing and value the power supply and heating element to match that. With the scale you're working on you're not going to need a huge amount of heat though so a small pencil torch would probably work fine, unless you're in a REALLY enclosed space the gas setup might actually be safer than an electric one.

One problem you may have with such a small boiler though is that as engines like that get smaller they get faster as well, and the pitch they produce changes. So while you might be going for the authenticity of steam power the sound and feel of a miniaturized steam engine is going to be nothing like a large sized setup. If you want authentic sounding setup stick with electric drive a good sound effects system and the fake steam like Mike suggested.

Just as an example, imagine the whistle of a train, if you were to make one to scale and push air through it you'd get a tone so high you'll irritate nearby dogs =) The same thing will happen to the noises the engine makes.

Check the hippy ornaments shops. They have little stainless steel ultrasonic water vaporisers, usually with a coloured LED. They put them in a little bowl with some rocks and make fountain/water scluptures with fog lying on top etc.

Actually I'm pretty sure ebay will have plenty on offer.

One idea for a heating element might be a 12 volt soldering iron, then if you can regulate the power going to the tracks you could control the heat.

Many thanks for the replies. Hornby manage to generate enough steam from a low voltage supply (I think around 18V though not sure) for their gauge OO live steam models (4mm scale). I am proposing to build in a much larger scale and I know that power increases as piston size increases, therefore cannot see why it is not feasable. I know that electric kettles are produced for the caravaning fraternity running off 12V supply, and pressume these do boil water.
I was wondering whether cartridge heaters may be used as I have seen one that runs off 24V DC at 60W that reaches quite high temps though whether it would require to high amperage (don't know formula to check)
James

James Field said:

Many thanks for the replies. Hornby manage to generate enough steam from a low voltage supply (I think around 18V though not sure) for their gauge OO live steam models (4mm scale). I am proposing to build in a much larger scale and I know that power increases as piston size increases, therefore cannot see why it is not feasable. I know that electric kettles are produced for the caravaning fraternity running off 12V supply, and pressume these do boil water.

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They take a LONG time to do so, they only accept small quantities, and take a LOT of power to do it.

If you've got an 18V supply, with 2A capacity, then that's only 36W - a kettle is usually 3000W or so.

As long as you're not constrained by the voltage you feed to the track, and it can carry enough current, then I suppose it's possible - but it seems rather a silly idea, and grossly inefficient.

**broken link removed**
That show how it is done. I think that the electric motor is to control the valve gear.

The steam engine via electricity is stupidly inefficient, although it has been done on full size locomotives. **broken link removed**

However, a model railway is just for fun anyhow, so why does efficiency matter? Heating a hot tub by electricity is much more energy-intensive.

I would guess that a steam electric loco is 2% efficient and motor of that size is 40% efficient, so you should aim for about 20 times the power, but I guess you could see what the Hornby one uses. You could go to 50 V and a couple of amps. The limit would be safety for voltage and welding of the rails for current. Power is just the voltage times the current.

Many thanks Driver300 for the info on the Hornby Live Steam. It looks as though a cartridge Heater is used for generating some steam in the boiler which then passes through a second cartridge Heater to supperheat for better pressure. It looks as though I will have to plump for convetional methods of heating a boiler if I want to produce a model running on steam. It was worth an enquirey to see if it could be practical. I thank everyone for their thoughts and input.
James

James Field said:

It looks as though a cartridge Heater is used for generating some steam in the boiler which then passes through a second cartridge Heater to supperheat for better pressure.

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Super heat doesn't increase the pressure. It increases the temperature. The result is that the steam is further from the point where it will condense.
Combustion boilers have superheating tubes that heat the steam more after it has left the boiler, for the same reason.

I would have thought that electric heating is perfectly possible, especially as Hornby have done it with.

Have you got any specification or pictures for the locomotive that you are using at the moment?

You might look into something called "smoke juice" It's used in fogger machines. It might take less energy to generate what you want. I wanted to look into it for a Halloween effect, but never really did.

Smoke juice is pretty easy to use, you just heat it up and it smokes. Has a small some people don't like but it produces very good puffs. A small bit of nichrome submersed in a small vessele of it woulld be relatively easy to construct.

Further to the request for information on the locomotive:
**broken link removed**
The above is the model that I am currently building to 1:24 Scale. The reason for looking at the possibility of electric heating for raising steam is:
a) the need for electical supply to work two servo motors for steam regulation and the forward/reverse valve.
b) the need to accomodate the electronics for such controls.
It was thought that if the gas tank and associated components could be done away with this would release more space within the chassis.
The cylinders are 12.5mm bore with a 18mm stroke which should be large enough for reasonable control of the model.

James Field said:

Many thanks Driver300 for the info on the Hornby Live Steam. It looks as though a cartridge Heater is used for generating some steam in the boiler which then passes through a second cartridge Heater to supperheat for better pressure. It looks as though I will have to plump for convetional methods of heating a boiler if I want to produce a model running on steam. It was worth an enquirey to see if it could be practical. I thank everyone for their thoughts and input.
James

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I don't know if it's just me?, but from what I can see on the nice PDF file Driver300 posted, it's a standard electrically powered engine?. The steam generator is only to make steam for cosmetic purposes?

I thought that at first. However I now think that the electric motor is to move the valve settings. It does what the reversing lever does on a hand-operated steam engine.

If you look at the instructions / FAQs from Hornby, there can be situations where the locomotive speeds up when it's supposed to slow down. I think that is because the valve gear isn't where the control electronics think it is. Anyhow, I can't believe that would happen if it were electrically driven.

Diver300 said:

I thought that at first. However I now think that the electric motor is to move the valve settings. It does what the reversing lever does on a hand-operated steam engine.

If you look at the instructions / FAQs from Hornby, there can be situations where the locomotive speeds up when it's supposed to slow down. I think that is because the valve gear isn't where the control electronics think it is. Anyhow, I can't believe that would happen if it were electrically driven.

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I was basing it on the diagram, there didn't seem any steam engine parts, and the motor looked fairly well connected to a drive train to the wheels.

Nigel Goodwin said:

I was basing it on the diagram, there didn't seem any steam engine parts, and the motor looked fairly well connected to a drive train to the wheels.

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I think that items 20, 21 and 23 end up with vertical rotation, geared down by two worm gears from the motor. Item 40, 4 O-rings on the cylinder block, doesn't look like it would be there if not needed. I'll admit that that drawing lacks a lot of part numbers and doesn't show it all assembled, so there are big gaps needing big assumptions.

I agree that the Hornby Drawings are not clear, I believe these were only produced for spares ordering. My understanding is however that these small locos were steam driven and the electrics operated the controls in a form similar to DCC. This is why I raised the question in the first place
James

I think you will have trouble making enough real steam to power a model that size, it's pretty big! You would probably need a couple of hundred watts and or some tricky boiler insulation.

Your best option might be to use a standard system like a small kerosene burner for generating the steam in the boiler, then run low power DC and a typical controller for the electronics like the servos etc.

Im thinking along the same lines as Mr RB, solid fuel pellets or sterno (gel fuel) last a good bit of time, for their size and can boil some water.

You want the steam engine to turn a generator to produce the power required for the servos only or also the whole drive "train"?