monotube boiler question

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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Richard Orr
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monotube boiler question

Post by Richard Orr » Tue Dec 15, 2009 2:34 am

To controll a too hot fire in my box wood stove, I have in the past, reduced the temperature by dousing the coals with a spray of water over the flames. I know about problems related to constant running the boiler exaust gasses at "dew point" and the dangers of cooling a firetube or even watertube boiler too rapidly but I am wondering if this method could be used to control a monotube on standby or in an emergency.
farmerden
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Re: monotube boiler question

Post by farmerden » Tue Dec 15, 2009 7:08 am

Maybe the key word here is "emergency" In an emergency you have to reduce pressure and heat and quick! I've found that coming into dock or to load the boat on a trailer simply using the injector reduces pressure and cools the boiler by adding water but the water is warm not cold.And after a while you can predict when the shut off the fire and not run out of steam too early-Now thats embarrassing! I once did that coming into Canada Customs in Sidney I had the whole narrow channel plugged while I built up steam with all these million dollar infernal combustion boats impatiently waiting behind me! Den
87gn@tahoe

Re: monotube boiler question

Post by 87gn@tahoe » Tue Dec 15, 2009 7:48 pm

Perhaps a pressure regulator controlling the closing and opening of the damper door?

Also a "clutch" for the engine, so that you coud use steam and circulate water through the coil, without going anywhere (The Wayard Belle has this feature, but she is strictly liquid fuel fired).
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barts
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Re: monotube boiler question

Post by barts » Thu Dec 17, 2009 7:27 am

If you're considering a solid fuel monotube, 87gn is right: I'd make _sure_ that there was some way of getting water into the tubing when the proper wasn't turning.... I remember Wendel Early (sp?) had a boiler design he called "flash overfeed", where about 2/3rds of the way along the monotube he had a steam trap
fitted w/ a discharge he could see into the hotwell. He'd adjust the boiler feed rate so that there was always water coming out of the trap, which meant he could add more feed water if things got too hot so he didn't overdo the superheat. I believe it was patterned after a Herreshoff design... anyway, this design worked very well on his paddlewheeler named the "Indian", IIRC.

- Bart
-------
Bart Smaalders http://smaalders.net/barts Menlo Park, CA
87gn@tahoe

Re: monotube boiler question

Post by 87gn@tahoe » Thu Dec 17, 2009 5:08 pm

Jim Tangeman would be a good authority on solid fuel firing of a monotube.
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fredrosse
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Re: monotube boiler question

Post by fredrosse » Fri Dec 18, 2009 4:37 pm

I had a small monotube boiler, and steam pressure would move about much too quickly to allow solid fuel firing. My boat was fired with propane. There is a short film of this plant on Radow Rainer's website, (look up "steam scanoe") and you can observe the steam pressure jumping up about 20 psi between each admission of steam to the engine! If you have a larger steam reservoir, then the pressure swings will not be so rapid, however I would think control of a monotube boiler with solid fuel firing would be challenging.
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Re: monotube boiler question

Post by stevey_frac » Sun Feb 07, 2010 10:18 am

You can read about the woodfired monotube boiler aboard the SL Alba here. He details his method of controlling his plant.
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