The Steamboating Forum

A Forum for the discussion of Steam Boats
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 Post subject: Hi Everyone
PostPosted: Wed Nov 18, 2009 2:53 am 
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Anne from Little Britan
Anne from Little Britan
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Joined: Tue Nov 17, 2009 11:17 pm
Posts: 232
Location: Roseville, MN
Posted on behalf of Maltelec:

Maltelec
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Joined: 23 Sep 2007
Posts: 156
Location: Cumbria, UK
Posted: Mon Sep 24, 2007 4:35 pm Post subject: Hi Everyone
Hi.

My name is Simon Maltby. I am 23 years old, from Cumbria, UK. I have been into steamboats all my life and I steam my dads boat on Windermere when possible.

I always attend the Windermere steamboat rallies and am currently trying to design my own boat, engine and boiler.

I hope you like this forum, I started it because I couldn't find a forum like this one for steamboats. I hope it will become a successful forum for all thoes who are interested in steamboats, regardless of their size.
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mcandrew1894
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Joined: 11 Oct 2007
Posts: 149

Posted: Thu Oct 11, 2007 4:59 pm Post subject: Fellow builder
Hello,

Glad to be here!, I am also building a 25 footer and engine and boiler.

We should perhaps compare notes!

I'll try to post some pictures shortly.

Regards,

Dave Piper
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Maltelec
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Joined: 23 Sep 2007
Posts: 156
Location: Cumbria, UK
Posted: Sat Oct 13, 2007 3:10 pm Post subject:
Quote:
We should perhaps compare notes!


Are you sure you want to see mine?



From the look of it, I was using the Sine rule to work out the distance between tubes as an angle on the boiler design, and to the side I was calculating the ideal shaft size for the duplex pump.
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Maltelec
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Joined: 23 Sep 2007
Posts: 156
Location: Cumbria, UK
Posted: Tue Oct 16, 2007 5:03 pm Post subject:
Just finding one of my notes it may be useful to many people, its how to calculate how much steam (and thus water) your engine will use. Very handy to know what size to make your feed pump.

1st off you need some steam tables which tells you the volume of steam at a certain pressure.

E.g. 11 bar = 0.1773m^3 of 1kg of water.

So, 1kg (1 litre) of water takes up 0.1773 meters cube of saturated steam at 11 bar. Incedentally water boils at 184.1C.

Now you need to know the displacement of your engine per 1 rev.

If you have a compound, you take the HP cylinder, and any water entering the LP must have passed through the HP first.

If I take my engine As shown here, it has a 100mm bore, 80mm stroke per piston and is single acting.

It is important to work in only 1 unit as it is very easy to become confused. So 100mm is 0.1 meter, and the combined stroke on my engine is 160mm = 0.16m.

Volume of a cylinder is Pi x (diameter)Sq / 4

Pi x 0.1 x 0.1 / 4 = 0.007854 meters Sq.

Volume = surface area x length

Volume = 0.007854 x 0.16

Volume = 0.001257 meters cube.

In my engine case, it does twice that being a single acting twin.

So the displacement is 0.002514 meters cube every rev of the engine.

At 11 bar (because it starts off from 0 bar, you must also add atmpospheric pressure to your pressure gauge, so 10 bar on the boiler is 11 bar of steam with respect to a complete vacuum), steam occupies 0.1774 meter cube/kg.

0.002514 / 0.1774 = 0.01417kg

So once every rev, the engine will use 0.01417 kg of water.

At 400 rpm, it will use 5.67 kg of water a minute, 340kg water an hour = 750 lb of water an hour.

Taken that this is at worst case, and going flat out with no cutoff, it is reasonable to assume that the engine would never actually take this ammount of steam.

As for how much the feed pump should deliver, you want the feed pump to be able to supply more water than required in the worst case, so a feed pump which can supply 10kg of water a minute (10 litres) should easily cope with any demand for water.
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