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Author Topic: Water tower type boiler  (Read 166 times)


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Water tower type boiler
« on: April 11, 2021, 01:05:42 pm »

Just to present you my new boiler .
The high part is 115mm x 60 high.
The bottom part is 90 mm x 80 high.

It is based on the water tower shape but the inside is quiet different. I have choosen to set it with vertical boiling tubes instead of horizontal ones.
The reason is that I have a bigger surface in an identical volume , exposed to the flame .
Ex : Available length on the furnace where to weld boiling tubes = 7 cm.
      - The calculations are made for the the  same ID furnace and same 6 mm boiling tubes.

Letís take 7 ea horizontal 6 mm OD tubes welded inside the 32 mm ID furnace  > 32 mm X 7 tubes = 224 mm exposed to the flame.
Letís take 6 ea   vertical    6 mm OD tubes  x 50 mm long inside the same furnace  > 50 mm X 6 tubes = 300 mm exposed to the flame.
I have 33% more surface with vertical tubes.  . Obviously , without calculating the heating surface , we can see that vertical tubes will produce more steam.

The other reason why I favor vertical tubes is that they are always supplied with water from the bottom and that the column of water along side a tube is heated , lifted and vaporised up to the top of the boiler. The trip of the water inside a 50 mm tube is longer than the one in a 32 mm One. So , the steam production remains good as long as there is some water in the boiler.
At contrario in a boiler with horizontal tubes , the performance declines when the water level goes down and leaves the tubes above the water .  The flame then , heats a dry tube producing nothing but acting as a kind of a dryer . On top of it, dry tubes in contact with flame is not recommended.

Another trick,  I place my tubes , bottom/up excentred , in a way that the flame is disturbed (see the drawing) , and ę  licks Ľ a bit more the boilers tubes. Is is efficient ? On the paper , it looks like it is ! In fact ?  It probably does not make too much of a difference but why to make it easy if itís possible to make it difficult ? ! ;-))

The only difficulty in building this boiler is to be very carefull in positioning the vertical tubes. They have to be line up properly. If not , it may be tricky to weld the last one . Like it happens to me once !
The pics show the different steps of the manufacturing.

The first  videos show a test with a 20 cc very badly machined down Brunel engine and leaking as much as it can ! The worst deal I ever made on Ebay!
I hardly stand 1 .2 b @ 600 rpm with a 130 g/h blow torch. I have good hope to improve the performances when I shall have fixed this ę scrap Ľ and with a 300 g/h blow torch.
Finally, after fixing the leaks and , milling the sliding surfaces , I end with virtually no leak but a tiny one on the top cap. The best I can achieved is 685 RPM @ 3 b gauge solid !
Autonomy = +/- 23 min. Not bad for such a boiler !

The second one shows a 8/9 cc TVR Graham running @ 1300 RPM and 3 b gauge steady. Blow torch : 130 g/h

I am quiet happy with the performances of this boiler and so much I am that , I offered  myself a  St Emilion to share with  friends.
You are my guests !
The little sister is on going. I mean the boiler Ö. but also the bottle should I say !!
I let you know the result later on for sure !
Best regards.
« Last Edit: April 11, 2021, 01:13:02 pm by KBIO »


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Re: Water tower type boiler
« Reply #1 on: April 11, 2021, 01:22:16 pm »

Some more pics of my trials.
The Brunel engine on maintenance and some videos of the performances.
A smaller boiler version of the boiler is under construction.
Thanks for watching.
Regards ! :-)
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