MadModder
Gallery, Projects and General => The Design Shop => Topic started by: John Hill on January 23, 2011, 11:03:50 PM
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... I am considering a small flash steam machine, small, but not a tiny model. Maybe 1 HP or so.
I would like light weight and a flash steam generator seems attractive. However, just about every example of a flash steam generator I have seen used liquid or gas fuel but I would like to run this on solid fuel, (not coal, )charcoal maybe or pine cones!
The question is, is there some reason the precludes solid fuel fires from use with flash steam generators?
Thanks
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John, I don't see any specific reason for not using solid fuel...
Most examples of flash steam boilers are used in high-performance environments, where I suspect they use liquid fuel or gas for the greater heating capacity per unit of fuel (there's a fancy name for this; I can't remember off-hand what it is).
The only other consideration I can think of is that solid fuels tend to burn dirtier, and in some cases may give off additional chemical gasses that could be corrosive to the pipe work - so more frequent boiler inspection might be sensible if used.
Regards, Arnold
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Hi John, echoing Arnold's comments, I'd also add a need for consistent fuel size, such as a grinder which produces repeatable output. A chipper/shredder perhaps? You also want to keep a steady fuel/air supply, so you don't end up with an oxidizing flame, or end up burning substantially less than complete, as you'd lose heat and have coking problems or excess soot. Maybe a vertical setup with a round grate and a rotating ash scraper, adjustable in speed, to keep the bed of fuel consistent, and able to set for maximum efficiency and the whole set up with the ideal setting at maybe 85% of that maximum burning, to give you some leeway for output to feed the engine. :coffee: jack
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Great idea John, sounds like a way to get free power, but the main advantage of gas or liquid fuel in flash boilers is that the burner heat output can be easily and rapidly cut when operating pressure is reached. This is not so simple with solid fuels but maybe some kind of damper on both the ash pan and in the flue could give good results, although if the steam usage was constant it would be less of a problem
cheers Stew
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The important thing to bear in mind with a flash boiler is that water should be continuously circulated, any steam produced gathered in some form of accumulator or steam drum.
Solid fuel is not going to be as easy as gas or liquid, but if you consider forced draught and put the fire at the top you can effectively shut the blower off to protect the tube(s) in an emergency or as automatic control. I'd think there would be a problem with ash in the flue though, no matter what the solid fuel is.
The Doble steam car's boiler operated this way but from kerosene using a carb and sparking plugs for ignition. The fire still travelled "downhill" and the tailpipe was pretty cool after the remnants of heat had been used to heat the feedwater. Abner Doble subsequently worked for the company who made steam buses in your part of the world (NZ) according to Wikipedia.
I'll be following your thoughts with great interest. Do some digging :)
Ray
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Thanks Ray. Yes I have heard of the Doble steam bus scheme but apparently not much came of it as I have never heard of any relics remaining and not even a photo of one.
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Hi Mr Hill,
I'm building a steam-powered scooter. I read about your seeking information on a flash boiler system. One element that I've found is crucial is the the regulation of the water/fuel ratio.
Here's some info you'll like:
(http://img.photobucket.com/albums/v187/andersonalien1/controlsystem.jpg)
The control valves are hidden beneath the plate and a single spring between the valve handles tries to close them both. The cyl on the left is the pressure control with the spring in it operating at right angles through a bell crank. It's just an air piston hooked up to the boiler output. The “cyl” on the right is an extension of the hottest tube across the tube stack and operates through a bell crank rather than through a lever. The plate which the controls sit on is attached to an external ring around the outside of the steam generator. The expansion of the hottest tube is being used for the steam temperature control here rather than using it for fuel safety shutoff...
Pancake Coil Winding:
(http://img.photobucket.com/albums/v187/andersonalien1/Winding1.jpg)
(http://img.photobucket.com/albums/v187/andersonalien1/Winding2.jpg)
(http://img.photobucket.com/albums/v187/andersonalien1/Winding3.jpg)
Hope some of this helps! :beer:
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Thanks Jason, that looks a big boiler, how many HP is that designed for?
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Most examples of flash steam boilers are used in high-performance environments, where I suspect they use liquid fuel or gas for the greater heating capacity per unit of fuel (there's a fancy name for this; I can't remember off-hand what it is).
Hi John, I know nothing about Flash steam.. but the term Arnold was looking for is Calorific Value.... :thumbup:
Good luck, Ill watch this with interest as the flash steam models I have seen (on Youtube) are SPECTACULAR to say the least....
Cheers
Rob
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Good luck, Ill watch this with interest as the flash steam models I have seen (on Youtube) are SPECTACULAR to say the least....
Cheers
Rob
It might be some time Artie. I just had an interger overflow error on indexing my project list! :doh:
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It might be some time Artie. I just had an interger overflow error on indexing my project list! :doh:
Ha! Dont I know THAT feeling.... and anyway, whos in a hurry?
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Hi John, browsing through the site and I found this thread.......... you've had a year now...... :) :poke: