COLUMBINE'S BOILER

[b.lindsey]

Glad to see you back on this Robert! I assume you are all done with the move and getting the house sold etc.

Bill

[fumopuc]

Hi Robert, good to see you back at this project. Hopefully the new workshop will push you.

[Robert Hornby]

After more procrastination I have managed to get my mind onto important things like gas regulators and stuff. 


Robert

[Robert Hornby]

Moving right along now and completing the burner assy. Next will be fitting it to the base of the boiler shell and hooking up the gas line from the regulator.









Robert

[Pete49]

Good to see you back at it. plenty popcorn and beer so go for it

[Robert Hornby]

The motor and the boiler have finally come together on a common chassis. This chassis will remain and be fitted to the launch in a way that I can readily remove it for maintenance. The next step will be fitting some pipe work between the two and then the good part of fitting the insulation and timber slats to the boiler. I will lift the boiler up a few millimeters to minimize burning of the wood as the base will get quite hot. A small piece of the insulation should suffice.



Robert

[K.B.C]

Hi Bob,
Firstly ,nice job you have made of the boiler, may I ask how you intend to light the ceramic burner ?

If you are to light the burner by a flame at the top of the boiler funnel You should be prepared for a bit of an explosion.

Your ceramic burner is about 3" dia and has a large space below the ceramic plate, if you are to light it from the funnel top as you turn on the gas the chamber will fill with gas  and fill the void above the ceramic plate below the bottom end plate of your boiler  before it starts to move to the funnel entrance and then some going up the funnel to hit the flame and I will be very surprised if you don't have a loud "BANG"

I have built quite a few boilers ,horizontal and vertical along with several YARROW type and the Vertical ones all have had to have air holes around the bottom and a fire hole to light the Burner, I don't know if you have considered these points but well worth the thought.

I am posting some pics of a Vertical multi-tube boiler of 3.5" dia x 7" between the end plates with a steam dryer at the top, if I didn't have the fire hole there would be a serious explosion if I tried to light ther 2" dia Ceramic burner  from the funnel top.

This is my test boiler.

Hope this is of some help.

George.

[Robert Hornby]

George,
You managed to just beat me by a day regarding the firing of my boiler (I have been on holidays and saw your post in Bali but unable to respond from there - WiFi very slow) as on the day we left it occurred to me that I didn't know how I was going to light it up. I certainly would not have lit it from the flue and as the air inlet holes are not in the base as yet (not quite sure as to where exactly to position them) it could be seen as that method may have been my intent.
Anyway I love your little door for the lighting and obviously I will be able to see how well the ceramic tile is performing - so thank you very much for posting the photos, very helpful indeed. I also like your super heater but unfortunately I have gone too far to add that now to my boiler.
Robert

[K.B.C]

Robert,

The size of holes on the bottom of the shell can be any dia that you want but as I intended to light my test boiler via one of these hole I made them 7/16" dia spaced approx equal around the shell but this didn't work as they were too near the base of the burner and I couldn't get the flame to the top of the ceramic.

The bottom ring with the holes is just a piece of the original shell cut to give 3/4" clearance from the ceramic to the underside of the bottom boiler plate, on hind sight I should have made it to give 1" clearance at least as when I had to cut the hole for firing I was very near to the underside of the boiler but enough to let me get the gas torch in to light the burner.
Remember Sandy's comment on the clearance from the ceramic to the underside  of 3/4" is a minmum.

Another point I would point out to you is that the ceramic burner copper base will get very hot and charr any wood that it touches, in one of the pics of my test boiler you can see the charred timber base, in this case it didn't matter but if in a boat it could cause trouble.

Anoyther couple of pics of another boiler built for a friend, this was a 5" dia boiler.
The burner is made from a square section of brass tube  2" x 2" and as a seal around the ceramic I use Gun GUm , which can be had from any auto shop for sealing exhaust seystems.
As a bottom support I left a big gap to allow the burner access, the ring was made from a spare cutting of the boiler shell.

Hope this helps

George.

[SandCam]

Hi Robert,

Boiler is looking great and should perform really well.

George is quite correct, you do need some additional air holes around the bottom since the burner will need secondary air to perform properly.
With a burner of this size it is not possible to entrain sufficient air in the gas mix via the jet tube venturi holes alone to ensure complete combustion.

You will probably require at least 6 possibly 8 x 1/2" dia holes around the bottom of the barrel with the top of these holes being at or just slightly below the top of the ceramic.

A lighting door would be a nice touch and would finish the boiler off in style, however, the burner can easily be lit via one of the side holes.

Whilst on the subject of the burner... Have you sealed the ceramic into the burner body around it's outer edges, this is not clear from the pictures posted which seem to show it just resting on the support tabs.
As shown there are some fairly large gaps around the edges which will cause problems since the gas can escape through this gap rather than passing through the holes in the ceramic.

I always seal mine using High Temperature Silicon sealant which, being flexible when set, also allows for some expansion.
Fire cement sets too hard and will not permit expansion thus possible leading to the ceramic fracturing.

You may have already done this but not posted a later photo so my apologies if this is the case but just though it worth mentioning.

Good luck when you finally fire it up.

Best regards.

Sandy.

[Robert Hornby]

Thanks again George and Sandy for the valued input and hints. I was always going to put the breather holes in the base, I just haven't chosen the radial location yet. Also I will be adding some insulation between the feet and the timber rails. I will also be sealing the ceramic to the burner shell with high temp silicon. Sandy, I did manage to break the tile (being quite incredibly stupid at the time) the break is quite straight and can hardly be seen when fitted into the shell. Do you think I should try to make a new one or will this one still be OK ?
Robert

[Robert Hornby]

Some significant progress has been made 
A second ceramic tile was obtained from my friendly second hand tile supplier and shaped to fit the holder then sealed with 350 deg. C silicone as recommended by Sandy.


Then the moment of truth  -  lighting it up. The flame seems to be more centered around the rear of the tile (away from the nozzle) hard to see, but just visable.


Anyway I fitted it to the boiler to see if it being enclosed would make any difference and it did seem to be a better flame balance, although it is a bit hard to see.



The gas line layout will be similar when it is in the boat but with a longer pipe, aprox 400 to 500 mm


It took only 5 minutes to bring the water to boiling with the regulator set to about half way, looking closely you can see the steam emitting from the ports


So all in all I am pleased with the burner and maybe if the flame is not too even all over the tile it wont matter so much.
Robert

[Ian S C]

Robert, have you thought of using a Piezo igniter, you should be able to get one at the barbeque shop, I use one on one of my hot air engines, the button is about 8" away from the ignition point.
Ian S C

[K.B.C]

Robert,
I would like to see the ceramic plate on your burner glowing bright red below your boiler.
I don't think that you have enough holes around the base, on my test boiler there are 9 off - 3.8" dia holes around the base  and as you can see in the pic the Ceramic is glowing bright red, the gas jet is a No 3 and the gas regulator is only 1/4 open.
The blue flame will heat the water but I am suer that you will get a head ache from the fumes of unburnt gas.
Try sitting the boiler and the burner  on 1/2" packers and see if the Ceramic glows red.

Have a look at my previous post with pics. Post No81 showing the holes in the boiler base with the Ceramic glowing red.

George.

[Robert Hornby]

George
Thanks for that, I have 6 holes 10mm dia around the bottom of the shell and even with the little door open (28mm x 18mm) it is still blue. I ran the burner outside of the shell and it still did not turn red as yours does so may be it is a setting issue with the nozzle. The blueish flame raises about 50mm above the tile, is this too much? The nozzle hole is as I bought it  i.e. with the factory pilot hole but I do not know what size it is, I do not have a drill bit small enough to size it.
Robert