On wire mesh burners:
Here's the new parts being made by "proper" people, that have appeared in their brochures only this year I think? - I didn't find anything when I was looking a year or 2 back... but have now found a few manufacturers using knitted NiChrAl wire wool or knitted fabric. - You can buy the material (min $100 + postage) from China.... but buyiong burners is obviously easier. e.g.
https://heating.bekaert.com/en/product-catalogueBut I'm sure the manufacturer's will know the (normal) life-time, service interval (and make a lot of money from) and "annual" replacement of "burnt-out" burners....
My GUESS is that you'll get a season of steaming a loco with one of these burners, but maybe not 2?
"Cemadore" shown attached is a Bekeart burner - type: Furinit/Duonit 98mm diameter x 100 high... Used in a large 5in. Pacific loco fiebox at up to around 25~30kW. - Propane jet with venturi for air induction: So far I am only able to make about 1/3rd of that power without creating uncontrolled "flamations" with my version...!! - But I'm working on it....
However, the "experts" have done the development, and can make burners better than I can and at my costs for materials, they are a reasonable price(!). Considering their burners are "safe" - and people can just buy something for less than £100 that will power their loco worth thousands of pounds, I guess you "pays yer money"... etc.!
"Supersaver" burners use an inner "can" with very narrow slits for gas entering the combustion zone, which is inside the wire "wool" matrix. Then, as the gas exhaust is still very hot, they heat the gauze that is spaced away (1cm?) from the combustion zone, and that glows red-hot as well, increasing the radiant fraction of heat emitted from the burner.
BUT: (And here's the Engineering), many "coal fired" boilers do not easily adapt to a radiant gas burner, as the coal (smoke) contains a lot of particles that glow and burn even when passing through the flue tubes, thus imparting a lot of heat to the water/steam, that is NOT available in Gas fires locos. So if the gas burner isn't suited to your boiler design (fire-box size, and flue-tube CSA really) then you are stuck with coal. I would design a different boiler to be oil or gas powered to the boiler for coal or wood firing. (Wood-fired have twice the fire grate size to coal-fired I think?).
The real calculations are whether the burner you can fit in your firebox gives you enough heat (large enough jet size and matching venturi needed to get enough air to rapidly and cleanly burn all the gas!); the radiant heat to heat the fire-box, and enough remaining exhaust gas heat to heat the flue-tubes. Typically, radiant burners do not have a lot of "residual exhaust gas heat", relative to coal fired... so the boiler cannot achieve the same steam output with gas firing, as can be achieved with coal when the draught is forced....
If a boiler works OK with gas burners (like blow-lamps) that just give a lot of flame, then it will work BETTER with a radiant burner OF THE SAME GAS POWER...
Finally, ceramics are only able to achieve 50~60% of the poewer of steel wire radiants, because the ceramic with crack, melt, or otherwise overheat at (>950 deg. C). temperatures that the wire radiants can manage (~1250 deg.C).
To improve the "Power" of a Cornish boiler with a 1in blow-lamp type burner, I have made a sleeve of wire wool - approx 1 1/4in bore x 1 3/4in OD with a blind-end 1/2in thich that the flame blasts into.... and this means I can increase the size of jet by 1 size over the max that the boiler can take without the wire radiant sleeve. - It means that the heat is radiated into the walls of the fire-tube, rather than hot exhaust gas that goes up the flue!
I have no idea how better a wire burner may be for Flash steam, but I can imagine the tube burner arrangement shown will take a coil or 3 of flash steam boiler up the bore very successfully?
Enjoy!
K2