gas burners

[Garry ColesParticipant @garrycoles69390]

Hi, Happy new year to all modelers.

I would like to run my 2in scale D&NY traction engine in my workshop over the winter so as to not get smoked out with running it on coal. I was wondering if I was to build a ceramic burner to fit the ash pan area. (1) would it work, (2) would enough heat be generated, (3) what size can ceramic burners be made up to. (4) what size of jet would be reccomened as a starting point. Look forward to those New Years answers.

Garry

 

[JasonBModerator @jasonb]

Burning lots of propane in a workshop will introduce moisture to the air that is likely to condense on cold metal and make it rust. Fumes are another issue. Not to mention the actual steam from the exhaust

You will not get as much radiant heat from a ceramic burner into the sides of teh firebox so may not work that well.

[Garry ColesParticipant @garrycoles69390]

Thanks Jason. Naturaly I would run it only with the doors and windows open. So it would work, but might take a bit longer to get up steam.

[Werner SchleidtParticipant @wernerschleidt45161]

Hi Garry,

I had the same problem I had built a ceramic burner for a small 5 inch loco only for testing. But it was difficult to get one bar for testing. The fire box grate space was about 2 to 2 inch. I was not able to get enough power of it. What I found in the net about ceramic burners was not so promising. But in the other hand I found a few applications which are working, but no information why, they keept the secret.

Then I found this  http://ibls.org/mediawiki/index.php/Marty_Burners

These are copies of industrial small burner for special purposes, I found similar burner In Germany and Italy from special industrial gas burner burner suppliers.

I build up 4 burners for one of my 5 inch vertical boiler locos and tested it. I installed them with a holding plate instead of the coal grate. This plate had to be tunned that not to much air can come in that it is comparable to the function of the blowers by coal firing. Otherwise the suction is so high that the fire is thrown out. With this setup I made my test at an outside temperature of 6° C. I was astonished in 10 minutes I had 5 bar, with coal it last 20 minutes. I was able to drive permanently at my garden layout in a pressure range of 3 to 5 bar. Later I recognised that I had to adjust gas and helping blower and I can reach then a better result. My home made burner are a bit different for easier making of the top cap, but with the info in the link you can reach the same result These burners have a power of 2.5 KW. They consume at my ride of 2.5 Km and 1 hour about 0.5 Kg gas. I made now for an other loco with a grate of 6 to 10 cm a setup with 2 burner but I have to test it, now it is to cold for it.

I hope this helps

Werner

[bernard towersParticipant @bernardtowers37738]

Aren’t coal burning boilers a different design to the gas burning version?

[SillyOldDufferModerator @sillyoldduffer]

It will work, but not well,

Coal is a solid that burns with a relatively low flame temperature that fills most of the firebox with an incandescent bulk.  The bulk warms the whole firebox and boiler crown by radiation.  The coal provides a lot of heat, at moderate temperature, applied evenly to the whole structure.

In contrast, a gas burner in a coal firebox provides a concentrated hot flame likely to overheat the top of the firebox, whilst its very hot exhaust flows too quickly through the tubes to transfer heat efficiently into the boiler water.  Just sticking a gas burner into a firebox designed to burn coal is inefficient and might overheat the boiler in one place whilst the rest of it stays cool, and most of the heat escapes up the chimney.

The combustion chamber of a gas boiler is designed rather differently to a coal firebox.  It makes sure the hot gas is spread across the structure, avoids hot spots, and slows down the exhaust so more heat gets into the water.

Rather than redesign the firebox, I suggest putting several firebricks inside (the type made to store heat) the firebox, and heating them with a gas ring underneath.  They will take longer than a pure flame to come up to temperature and raise boiler pressure, but the heat will be spread around the firebox in much the same way as coal.   The bricks will also reduce the exhaust temperature, slowing down gas flow through the tubes so they work somewhat more efficiently.

Rough guesstimate from IMLEC numbers: 200W power out at the drawbar from a 2% efficient loco, which is a very good one, implies a 10kW burner, which is a lot more that a DIY store cartridge blow-torch produces, perhaps 1kW.   So several DIY store blow-torches would be needed, or an equivalent gas ring.   From memory, I believe the rings on a domestic gas-cooker top are about 600W (small ring) to 2kW (big).   Note though that a blow-torch produces a single big concentrated flame, whilst the rings have many small flames.   To see the difference, try boiling a saucepan with a blow-torch!  For this purpose, the concentrated heat from a torch is unsuitable, and much more wasteful than a ring.  Same issue inside a traction engine boiler.

My IMLEC guestimate is based on the heat needed to run a loaded loco round a track at reasonable speed.   Rather less heat will be needed just to turn a flywheel over in a workshop, in which case, a couple of blowlamps worth of heat applied for longer, raising steam slowly, might well be “good enough”.

For rough work, like raising steam for a test, a sufficiently big gas burner of any type given time will do the job, but far from ideal.  If the engine were to be run permanently on gas, the firebox would have to be redesigned, and would no longer burn coal, unless designed as a hybrid. Not simple.  Better to copy an existing gas design than start from scratch.

Dave

 

[noel shelleyParticipant @noelshelley55608]

Some speak highly of the Marty burners as noted by Werner. If you wish to experiment on the cheap then get hold of an old Super Ser gas room heater, all the rage in the 70s, ran on Butane ! With careful work one can cut down the fragile ceramic panel and make a box/burner to suit your fire box. Jet size, primary and secondary air plus gas presure all need to be just right for it to work ! Good luck Noel.

[John PurdyParticipant @johnpurdy78347]

Gary

If you have access to the Aug. 2020 issue of Engineering in Miniature there is an article on making a burner similar to the one alluded to by Werner above. Although for a 7 1/4″ loco it might give you some food for thought. I’ve sent you a PM.

John

[BazyleParticipant @bazyle]

Many years ago when I visited Los Angeles Live Steamers everyone was running their 5 & 7 1/4 locos on propane for fire safety reasons and lack of coal in California. So there must be suitable burner designs available.

[duncan webster 1Participant @duncanwebster1]

1. Gary, if you send me your email via pm I can send you endless articles about gas burners. As others have said, you need lots of little flames, but the lads in the USA have done it so it must be possible. It’s something I have on the todo list, but well down I fear

[Mark RandParticipant @markrand96270]

Would a brick arch attachment help to improve the effectiveness of a gas burner?

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