3” boiler project.

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DJoksch

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Thanks again for the papers. Just finished reading. I will see if I can mock this up today. I have everything but the stainless steel pan scourer.
 

Steamchick

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I bet your local ironmonger (hardware store) has packs of 2 for half a dollar!

Do you need a drawing?
K2
 

DJoksch

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I bet your local ironmonger (hardware store) has packs of 2 for half a dollar!

Do you need a drawing?
K2
A sketch would be great. I am working on a base to set the burner in. I think air should draw from below the actual burner.
 

DJoksch

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I ran the boiler against a Stuart V10 I plan to restore after completing the boiler.
 

Steamchick

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I shall knock something up tomorrow.
If you are raising the boiler, I'll do a sketch and suggest minimum dimensions, so you can decide what you need to do.
K2
 

DJoksch

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I shall knock something up tomorrow.
If you are raising the boiler, I'll do a sketch and suggest minimum dimensions, so you can decide what you need to do.
K2
Thanks! Copper lost some luster after being heated. Does not take long to heat up and make steam.
 

Steamchick

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What size gas jet did you use? And did you use Butane? Or Propane? Or a mixture canister?
Do you need more burner power to supply the steam for your engine?
K2
 

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Try this? - Being an Engineer, I could never relax and patiently do a proper drawing - Active brain - full of ideas and the hand too slow - even with a pencil - to record it... I used to get complaints from the draughtsmen that I knocked out stuff faster than they could cope... In a different job, the "union lads" complained the same... So I hope you find the sketches intelligible? Ask questions as needed.
K2
 

DJoksch

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This is fantastic. I am an electrical engineer and do some of my best work on binder paper. This looks perfect. I was reading up on the use of propane and butane. What would you suggest? The boiler heats quickly, but using the propane hot plate on a BBQ is probably not the scientific method. The engine I built has a 1” bore with a 1-1/2” stroke and runs easily. I knew that the feed tube dimensions and burner distance to the boiler were important.
 

Steamchick

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Hi DJ. A pretty simple decision. If you have temperatures above 60 degrees F when you run, small butane canisters work fine. But when the temperature drops to freezing, as it does in my garage when the door is open for ventillation in winter, the butane pressure drops to nothing! Propane, because of higher pressure, uses one jet smaller the butane, as a simple rule. But also may need the air holes 3/4 of the size for butane. You can use a sleeve to do this, like with a bunsen burner. The thermal heating effect will be the same, because too hot and the ceramic will flash back or even melt. So the limit is mid-orange colour.
I can give you different sizes if you run at millibars pressures.... Butane 30mbar, Propane 37mbar. But I suggest not for models of this size. You have not got the space in the plenum.
I use butane for boilers, propane for blow-lamps for silver soldering. Mostly because small canisters of butane are cheap enough and very convenient. Cold counties - eg Sweden prefer propane canisters, warmer countries eg Spain haven't got propane because they are warm enough that Butane is common.
I have made burners from 4 in diameter upwards using propane, at high and low pressure, and almost exclusively high pressure butane for 3 in diameter and below. High pressure = 5/16" inlet tube, 30mbar butane needs 1/2" inlet tube, so that is the main reason for pressure selection.
Let me know your decision in case you need different sizes to be checked.
Enjoy!
Ken
 

DJoksch

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It does freeze here from time to time so propane it is. I’m now making parts. I really appreciate all the technical help and your valuable time. I’ll post progress photos.
 

Steamchick

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Hi DJ.
What pressure Propane will you plan to use?
I would use 15 or 20psi typically, via a standard regulator, Which I think should be used with a 0.25 mm (No 8) jet, 2 x 3/16" air holes, into a 6mm / 1/4" mixer tube... By using a variable regulator I can go down to 5psi or up to 30 psi gas pressure, which gives very good adjustment of the power of the boiler to steadily maintain steam without blowing-off the safety. Otherwise you need a very good gas control valve to adjust the burner, but you don't know what the right setting is! When making a set-up nowadays, I prefer to actually have a base board, so all the gas control valves, pressure gauge - or whatever I want to use - is on the board permanently connected to the boiler. Then I only need to connect the gas hose from the Cylinder onto a connection on the board, so everything - including the tall and not so stable boiler - is safer to use on the bench. (I'll get a photo).
I have made a boiler burner (4" diameter) and set it for gas at 37mbar from a camping burner regulator, but then need a both stop valve on the propane cylinder, and another valve at the burner end, to adjust the supply and turn ON/OFF. - If that is what you have for barbecues, etc. and want to go that way, you'll need a 1/2" bore mixer tube, at least 3 1/2" from air holes to burner body, I think 2 x 3/8" air holes, and the gas jet will need to be 0.40 or 0.45mm. I shall need to make a mock-up and check, as the low pressure and small burner is off my table of gas power vs. jet size.
Please wait until I can confirm correct sizes, but please tell me what Propane pressure you will use? As this is all critical, I really want to prove it myself before you set fire to everything!
Don't rush, be safe.
Regards,
K2
 

Steamchick

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Just looked at your location for Jan to March:
Average temperatures would give some problems with Butane: But I think you are warmer than I am! But I do have difficulty with Butane from December the end of March on cold days (I expect 6 or 7C today!).
K2
 

Steamchick

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- I use this chart reading the Propane 20psi column for Butane at 15 psi, as it is about the same, correct to a few percent...
Gas flow (BTU/hr) is proportional to the cross-sectional area of the jet...
Gas flow (BTU/Hr) is proportional to the square root of the pressure. (5psi is half the power of 20 psi).
Butane carries 20% more power than Propane at the same pressure and jet - so needs 20% more air - but has less "kinetic energy" at the jet to suck-in air... so has larger air holes than for propane.
But for the same gas power, the same mixer tube size, diffuser and burner CSA is used.
For low pressure, Butane (In Europe is set at 30mbar, Propane set at 37mbar, so the "gas power" (BTU/hr) is effectively the same... I THINK? - Can anyone confirm this? - But I think they need different jets and air hole sizes...
Jet tables for the burners for boiler do not appear to exist, so I re-calculate - then check with a mock-up - before cutting metal.
Cheers, "Have a nice day".
K2
 

DJoksch

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We do get cold in the Winter. I was planning on no more than 20psi with a small regulator. My plan is to mount everything on a platform as you suggested. The platform would include a water supply tank with a hand pump as well. When completed, I plan to build or buy a tank similar to one sold by Stuart. I would add a regulator with an actual pressure gauge.
 

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DJ. A good plan! I was watching bank holiday sport today, so didn't get in the Garage. Maybe tomorrow?
Hope that doesn't spoil your plans.
Happy Easter! Hope you can celebrate with family within pandemic constraints. We are limited to meeting outdoors, with a max 6 from 2 households. But we are only a bubble of 4 so OK.
K2.
 

DJoksch

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DJ. A good plan! I was watching bank holiday sport today, so didn't get in the Garage. Maybe tomorrow?
Hope that doesn't spoil your plans.
Happy Easter! Hope you can celebrate with family within pandemic constraints. We are limited to meeting outdoors, with a max 6 from 2 households. But we are only a bubble of 4 so OK.
K2.
Have a great Easter!
 

DJoksch

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Just spun a 3” base and rough fit a piece of ceramic plate. Used the mandrel I made for the boiler end caps. I thought I’d show the ceramic to make sure I have the correct material. Easy slip fit into the boiler.
 

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Steamchick

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Looks good! Now: BEFORE you stick the ceramic to the tin....
  1. Is there a small hole in the centre of the base of the "tin"? - I'm sure you solder a blank over it if there is...
  2. Does the ceramic sit inside the spinning, or just on the top edge? If on the top edge, it will need to be affixed with silicon to allow for differential expansion between the ceramic and copper. If "half-inside" the copper spinning, then you will need a good 1mm or 1/16" clearance for sealing with silicon paste and allowing for differential expansion.
  3. The outside can be "smoothed-off" with an application of Exhaust Sealer paste from the Automobile shop.... Cheap but high-tech sealer that is much better and neater than firebrick cement. But not good on skin, so wear Nitrile gloves when doing that job!
  4. But don't stick it together yet!!!
  5. First have a look in the larder for a tin of peas, beans, soup or whatever you are having for tea.... The tin needs to be the same size (or maybe a tad bigger) to take the ceramic. If you don't have a suitable tin, I have managed with a plastic tub, or heavy aluminium foil from a pie case and made a mock-up. You will probably destroy it later, so that's why I use these materials. They are not as strong as the ceramic, so they can be hacked off carefully with scissors or something if necessary.
  6. When you have the "Mock-tin"... Make the proposed gas-air delivery tube and jet and fit it into the mock-tin with silicon seal. Fit the ceramic - I use masking tape as it will be on and off a few times! The outside (Your machined surface) of the ceramic is all pitted and won't seal, so you can fill the bottom 1/8" with silicon seal, smoothed so it fills the grooves, or you can fill the side grooves completely using the exhaust assembly paste. ALLOW TO SET.
  7. Put a 1" ball of pan-scourer stainless wire wool about 1/2" away from the end of the inlet pipe. (Not tightly compressed, quite open as bought from the store). Sit the ceramic on the mock-tin and seal it (This is where I use masking tape...).
  8. Connect to the gas canister, and try the burner. Only for a half minute or so, and not "full gas". Maybe photograph or sketch the surface colours so you can keep track of changes. Then turn OFF and allow to cool.
  9. It is likely that the burner will have some hot spots and grey areas. (cold spots). Lift the (Cooled) ceramic and try a bit more, or less wire wool until you get and even burn across the face of the burner. Taking photos I find useful as it enhances the colour so it is easier to spot cool spots and hot spots. These variations must be eliminated as much as possible, as otherwise the ceramic will crack with differential expansion and contraction, after a few cycles.
  10. When you have an even burn, try the pressure variation from "just lit and stable" to a "mid-orange to bit brighter" - AND RECORD the PRESSURES. If the burner roars or sings, you probably have too much gas, too lean combustion, or a particle of something you may spot as a black dot or yellow to white dot on the surface. TURN OFF THE GAS BEFORE YOU BURN-OUT the ceramic and get a flash-back. Turn the gas down a touch to a good mid-orange - and call this setting "Maximum".
  11. Now try it in the boiler, and study carefully. The different conditions (constraining the exhaust, back pressure, heat loss to boiler metal) all affect the combustion. Most noticeably, any back pressure that changes the gas-air balance and mixture. Too much flame - trying to escape rather than going up the flues will mean you have to turn down the gas and set a new maximum. If all looks good, check the exhaust from the top of the chimney, by "grabbing a handful and smelling it". DON'T stick your nose over the chimney. If there is a lot of CO, you won't smell it, just poison your blood. carefully try to move a lighted flame into the updraught of hot exhaust gases. (I use a barbecue lighter 6" long so my hand is well clear). It should extinguish without any flaring with a dark blue (Ghostly) flame.
  12. When you are happy, strip-down the mock-tin burner, and rebuild into the proper tin, sealing between the ceramic and copper spinning with silicon sealer, and covering that from the flames at the top of the ceramic with the auto-exhaust paste.
Sorry this is long-winded, but necessary for me to do on every new burner, to be sure it is right. I think you'll find it works for you too?
Enjoy modelling! - I do!
K2
 
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