3” boiler project.

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DJoksch

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I’m building a 3” boiler from scratch. The area for water is 3” X 6.5”. In the pic is a test braze that I did not like. The final result worked out nicely. I am building a ceramic burner and just got the ceramic material. The feed pump is ready to go and I should be able to complete the boiler this weekend.
 

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darwenguy

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Good luck with the soldering. Some lovley looking copper work there.
What will you use for pickle?
 

DJoksch

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This is my first boiler. My dad and I ran a clock and instrument repair operation so I used old cleaning solution which seems to do the trick. I just swedged and soldered the fire tubes after doing a few practice tries on an end cap I did not like. I found a thick 3x3.5 foot sheet of copper in the old shop that met the thickness needs for the caps. When I turned the edge on the first end cap as on a YouTube video, it was too thin. The final versions were spun and came out nicely. I am trying to decide where to put the accessories and if I need two relief valves.
 

DJoksch

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I made an template and left it on the lathe. I annealed the copper several times as I used a mallet to get it close. To finish, I used a bar on my tool post with a bolt for leverage. I got away with this because the copper was soft after heating. Using a 1” bar with a smooth rounded end I pushed the copper over the rounded edge and worked the edge flat. This process goes very quick and gave a nice flat surface.
 

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DJoksch

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I like the dome idea. Start from the center and work out. You want to use some finesse letting the metal will tell you what to do. I work all the way to the edge so it works to the overall shape on each pass. I am still learning myself. Wear gloves in case it slips.
 

Steamchick

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Hi DJ.
I have made a couple of dozen burners, ceramic burners fro 1/4" x 1 1/2" to 7 1/2" x 5 1/2".
The simple rules are all based on "how much steam do you need, and at what pressure?"
Now the boiler can deliver whatever it will, depending on heated surface area, both radiant and from conduction from hot gas. If you can send me some idea of the firebox sizes (3" dia: but how high?), flue tube sizes (12 tubes? 1/2" ID?), etc, then I'll do some quick calculations and make a recommendation for the "most powerful option". I guess a 2kW ceramic (3" diameter) may be all that will fit, but we'll see?
But first a couple of points for you to ponder... (no criticism intended or implied).
  • Shiny copper looks beautiful, but loses a lot of heat by conduction and radiation. My boilers are well lagged, so I can hold them - nice to warm the fingers on a cold day, but just warm, not hot. The heat you lose is just wasted "lack of steam". The outer layer of lagging by narrow "planks" with brass banding is a common finish - on real boilers and many models. Multiple layers of insulation beneath - interspersed with aluminium foil - make very good insulation against conduction and radiant heat loss. But hide that polished copper.
  • Most engines prefer DRY steam: I.E. taken through hot gases to heat it a bit more after being taken from the boiler head-space and before it gets to the engine. Yours look like it takes steam directly from the head space? Or are there some drying/superheating tubes hidden there?
  • Lagged pipework can look very authentic: I carefully wind cotton string around my pipework and paint with white emulsion to look like pipes do on real steam plant. It also insulates quite well.
  • The beautiful "reversed trumpet" makes a gorgeous chimney! A show-piece of spinning? (or scrap trumpet?).
  • The polished copper and brass will change colour (tarnish) with firing the boiler, so I hope you have a lot of polish...
  • Have you had it independently checked and tested by an expert? - That is a satisfying (and safe) task. Keeps the insurance Company on your side as well. I do approve of your use of Regulations in the design. Keep a good copy of the calculations and details of the silver soldering, drawings, etc. safely stored with any other documents for the boiler.
Attached some technical information on "Burner power". Pages 6 & 7 show relative "Power" of burners. Compared to coal fires (which are about the same as the Porous burner): Ceramic burners are rated industrially at something like 1/8 of the heating ability of coal. They can be boosted a bit in a boiler, as a bit of "top-flame" can be made which heats the flue gases a bit for conduction of heat to the flue tubes as the exhaust passes up. But maybe only 10 or 20%... A regular gas burner with stainless steel wire wool over it is more like the wire burner 1 better than ceramic. But a lot depends on space, flue tubes, etc.
What gas do you have there? Butane? Propane? Butane+30% Propane mix? - At cylinder pressure or from a pressure regulator? - I had a chat with someone recently who wants to use Natural Gas at 20mbar: Just needs a different design of intake to suit the appropriate jet. (I'm working on it).
Enjoy,
K2
 

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DJoksch

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You can see some tool marking at the top of the cap. I’m still learning. It has not had a final inspection yet. I just finished it yesterday afternoon. I have a square of material for a ceramic heater, but have to decide how to incorporate the burner into the boiler itself. I’m still making drawings. The boiler is 3” in diameter and there is 1-1/2” to the bottom end cap. I used old mahogany from a boat repair to clad the engine cylinder. I have enough for the boiler. Thanks for the burner information this is helpful.
 

Steamchick

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DJ. Of course there are many ways to do this, and every thread finds at least 3 variations.
My "standard" boiler lagging comprises the following:
Cover the boiler metal with aluminium foil, shiny side out. I use spray adhesive to stick it to the boiler. Cover the foil with corrugated cardboard - again with some adhesive.
Cover the cardboard with another layer of foil, shiny side in.
You have now made something like a thermos flask and stopped 99% of the radiant heat losses, as well as a lot of conductive losses.
Then clad with the wood planks as a dress finish.
The are many insulating fabrics, and one of the best is wool, or cotton or a modern silica based stuff. The modern stuff isn't any better as thermal insulation, but takes high temperature better.
I use corrugated cardboard as so far my oldest boiler is 25 years old and it is still OK. It doesn't char at the temperatures of the boiler sides. Before silica fabrics became available, cotton flannel was common lagging fabric. Natural insulation - wool - is very good, as sheep wear it to keep warm.
I have also used a lot of balsa wood, as it is one of the most insulating of woods. It needs a stain and varnish to improve the looks.
If you want a design of burner I'll do a drawing, but there are many that work. If you don't follow a design that works, you can have a burner with hot and cold spots, that can flash-back, crack the ceramic, etc. I have experienced all the failures in 20 years! ( BUT I think I am doing it right now).
I reckon you need 1/2" each for a mixing chamber (plenum) beneath the ceramic, the ceramic itself, and flame space. Very tight, but the minimum I have used. Using Butane: A 0.25mm jet (no.8) with 6mm, 1/4" inlet tube, 2 inches as mixer tube, may be OK or but I think it should take a 0.30mm jet (no.12) with 8mm inlet tube as I think the flues are well capable of taking the exhaust. The air holes need to have 1.25 x the CSA of the mixer tube. Face of jet located at the leading edge of the air-holes. Put a drill in an air-hole and set jet to the drill.
Anything more, just ask.
Cheers,
K2
 

DJoksch

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Cardboard would not have occurred to me. So foil, then cardboard, and finally mahogany planks. A drawing for a burner would be great. I was just reading your last PDF file. The boiler showed no signs of leaking so I tried it with water this afternoon and it work nicely. The Clarkson engine I posted before I started this project runs on lung pressure so 50psi is certainly enough. I definitely need to connect the water pump. I read an article saying that I should install a check valve between the hand pump and the boiler. Your comments have been helpful.
 

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Steamchick

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I'm sure I saw this character starring in Disney's film Fantasia? Dancing around the kitchen perhaps? - Sorcerer's apprentice scene?
The boiler cladding should be: foil, insulation, foil, paper, wood, brass banding. You can even put paper beneath the first foil to hep adhesion by glue. 2 foils separated by insulation is the key to blocking the radiant heat.
K2
 

DJoksch

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I play double reeds and was asked how I thought it up. Clearly a Disney inspiration. In fact I often play with my orchestra friends Glenn and Dale Disney.
 

Steamchick

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Try this on ceramic burner making.... Making a Ceramic Burner.
Not perfect, but good for his small burners. Mine are a bit different:
But here are some basic parameters:
I reckon (off the top of my head) that a 3" diameter ceramic will have something like 300 holes at 1mm diameter: call if ~0.7 sq. mm CSA per hole allowing a bit of a constriction factor:
So you have around 200sq.mm of burner hole CSA: 1/4 of this is 50 sq.mm: Approx an 8 mm. or 5/16" ID tube: Therefore the mixer tune needs to be at least 60mm from the end of air hole to end of tube: The air holes need to be 25% more CSA than the mixer tube bore. I.E. 2 x 1/4" or 3 x 5mm holes. The jet should be a 0.3mm dia (no 12) placed exactly at the start of the air-holes. You can buy or make (if you can drill that small! - I do, but it has taken a lot of fiddling to get the accuracy of centre to drill without breaking drills).
Because the air-gas mix leaving the tube is vary fast, this causes pressure problems in anything bigger than and inch in any direction. So in a 3" "tin" (the plenum below the ceramic) I would put some wire wool from maybe 1/2" beyond the end of the mixer tube for about 1" in the direction of gas flow to slow the gases and distribute around the plenum. I like stainless steel pan scourer for this. Quite open, but does the job and is cheap and convenient material. A bit of trial and error will get a good even burn. It is easy to see hot spots and cold spots when firing. Less wire wool usually removes the hot spot, more slows the gas more and increases local pressure. A bigger jet will choke the air tube and cause blue and yellow flames and cold ceramic. So bigger burners to take bigger jets need bigger air mixer tubes. - Very often ignored by burner makers on the web!
Fix the ceramic into the "tin" with silicon seal. (From the Auto shop). I finish the edge on burners with a coating of Exhaust assembly paste. It cooks hard and protects silicon seal from burning. The ceramic is inserted half-way into the tin, with sealer, then a bead of exhaust paste covers that so the silicon is 4 or 5 mm below the top of the burner ceramic and covered by Exhaust paste.
Hope this gives you some ideas?
I have more complicated designs for larger burners, but this is about the simplest for you.
K2
 

Steamchick

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Here's a paper I prepared a while back - Warts 'n all! The last bit was something I have witnessed on odd (larger) burners, and I reckon is my "manufacturing inconsistency" of getting 3 air holes exactly symmetrical around the end of the tube.
Gas pressure is also a factor. Using Butane (this is a Winter job for me) the gas pressure drops. Recently I supplied a burner (tuned in a cold garage = lower pressure?) and the guy used 30% propane-butane mix, effectively doubling the gas pressure (increased power by a third) and the burner got too hot. A significant increase of air entrainment occurs as the "suction" is proportional to the square of the velocity of gas at the jet - which doubled per pressure increase - and the extra air will have caused faster combustion at the face of the burner. Mid-Orange is Good, Brighter (a tinge of yellow?) is TOO HOT! But a bit of air-hole restriction can accommodate the balance of air to cool the burner a bit and get it to back to mid-orange.
The boiler back-pressure is significant - when you reach a limit of the flue gas flow. But this boiler (12 x 1/2" flue tubes) should be well draughted.
K2
 

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