Ceramic Burner

[ChinkoaParticipant @chinkoa]

I am about to start building a 6" verticel Boiler. (Reeves Drawing)

I intend to fit a Ceramic Burner rather than use Coal. Not for any green reasons but rather convenience less mess to clean up.

My question, is their an optimum distance between the top of the Ceramic burner and the bottom of the Tubes thatr I should aim for?

The drawing gives a dimension between the Grate and the tubes of approx. 4.1/4" when using Coal.

Anybody got any experience of this sort of thing?

[ChinkoaParticipant @chinkoa]

[Harry WilkesParticipant @harrywilkes58467]

I don't have any any experience but a friend of mine got some great advise from Forest Classics link

H

[noel shelleyParticipant @noelshelley55608]

If your going to make a 6" boiler then why not make the burner ? Using the ceramic burner material used in the old super Ser roon heaters and some fire cement you can make a burner to suit your job and save about £50. Noel

[nigel jones 5Participant @nigeljones5]

You wont make a single ceramic burner anywhere near big enough to power a 6 inch boiler – trust me, ive spent a lot of time developing our burners. Whilst the burners from FC are great for mamod type boilers they wont burn hot enough for yours, and if you do get them hot enough the ceramic will dissintegrate. There is ceramic and then theres ceramic – you want the stuff Polly models sells. The biggest burner you will be able to make is 2" dia, and at that it will need a baffle plate. Any bigger and the gas mixing goes to pot. To add more misery vertical fire tube boilers dont react well at all to gas burners. They are designed for coal with draughting, not for gas without. I could (and one day might) write a book on burners so I wont go on. Your best route is to make three 1.5 dia burners. On our 5" and 6" horizontal boilers we use 1,5" x 2 and 2" x 2 respectively, but use cross tube flues as you need an easy path for the hot air to move through when non draughted. Best of luck. Nigel @ Pendle Steam Boilers

[duncan webster 1Participant @duncanwebster1]

This is opportune as sometime I intend to embark on a gas burner or my 5" vertical boiler. I've been collecting ideas off the interweb, and this looks worth a punt plate/pan. Clearly needs altering from rectangular to round, but the principle holds good

You might also try robRoy, a chap from New Zealand has made a successful burner for a Rob Roy which has secondary air inlets through the ceramic. I did have Doubletop's email but change of computer lost a load.

There appears to be some dispute over whether secondary air is needed. The Doubletop link and Fizzy's suggestion of several smaller burners suggest it is. I've also seen reference to a sort of doughnut shaped ceramic burner, a big hole in the middle lets the secondary air in. Suffice to say all the central heating boilers I've ever seen have lots of small slits for the flames, and secondary air.

Hopefully the OP will solve the problem for me and let us know!

I've got quite a bit more info, if you want it send e your email via pm

 

Edited By duncan webster on 18/11/2021 18:51:15

[nigel jones 5Participant @nigeljones5]

To add my experiences to a question Duncan raises – all of the required air (oxygen) in our burners is mixed outside of the burner adjacent to the tip of the gas jet – dimensions in this area are critical. We add air vents to all of our burners but these are purely to neutralise unwanted harmonics ( there isa lot more to burners than one might expect). When we test our burner design they are run at full throttle into an entirely closed off flue for at least 30 minutes. A cold burner and flue reacts differently to a hot one. The other alternative is to use individual gas jets, lots of them, but your burner would essentially need to be in the open air.

[noel shelleyParticipant @noelshelley55608]

I have a 6" verticle boiler of similar design ! One thought was a series of concentric rings of tube (copper) drilled with small holes (jets) and all mounted on a square radial pipe, fed by the main jet and a venturi. The venturi and main jet would be made so as to be changed or adjusted and the gaps between the rings would give well distributed secondary air. This secondary air would also be controlled by a damper below the burner/firebox. Thanks for your input Nigel, and write your book I will buy a copy ! So Nigel are you saying it is not possible generate enough heat to power a 6" boiler with gas or is it the case that no one has made a burner to do it ? Keep in touch Duncan and Chincoa, may be it can be done. Noel.

PS if the ring desgn in copper worked but was found to get to hot then rings of steel would be plan B !

[nigel jones 5Participant @nigeljones5]

you can certainly power a six inch boiler with gas – i make my living by doing it! What you cant do is make one big ceramic burner. Such a burner, if made correctly needs a very precise gas velocity and once the diameter goes above about 1.75" this is lost. With no draughting and small bore fire tubes you will be heating the opposing boiler face and not much else which defeats the point of having multiple tubes, as mentioned in my previous response. You need several small burners and their air intake needs an unhindered supply of cool fresh air i.e. not drawing air from inside the boiler shell. If you look at the photos of our 5" vertical boiler on our website **LINK** you will see the air inlet sticking out the side ofthe boiler base, photo 3.

[duncan webster 1Participant @duncanwebster1]

There are many instances of loco boilers with multiple fire tubes being successfully fired by gas, over in the USA they seem to use it a lot especially in areas prone to forest fires. I gave two references above, here's another USA, and there was an article in SMEE journal some years ago. Also google for Marty burners, ME 3169 and Engineering in Miniature May 2011. ME 4188 had an article on using a modification of a Sievert cyclone burner in a 5"g metro and a 3.5" Rob Roy. Even LBSC showed drawings of a primus stove burner in a model loco firebox, no idea if it worked but his stuff tended to.

Where I will agree wholeheartedly with Fizzy is that you are unlikely to have success in a muti-tube boiler without forced draught, too much pressure drop in the tubes. What you also need to ensure is that the gas has completely burned before it gets into the tubes, once inside it is cooled faster than the burning can heat it, the flame is extinguished and you get unburnt or partially burnt gas coming out of the chimney. (This is a bit of a simplification, but I believe basically correct)

I have a suspicion (no more) that you won't get the same output from gas as you will with coal. My vertical boiler has a 4" grate, so allowing 25 lb/sqft/hr grate loading (actual burning) gives 2 lb/hr, 28362 BUT/hr or 8 kW, the same as a Sievert 2941 burner, but you won't get that to fully burn in a firebox only 4" or so high

Finally there is a suggestion, and I can't put it higher than that, that a vapourised paraffin flame is more compact than an equivalent LPG flame. I have no hard data on that, just something someone told me. All we need now is for someone to take all this info and make a successful burner for a vertical boiler instead of my pontifications

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