Hey thanks for the info , although I'm a guy who don't like failure. My j tube already works even without insulation. (Although it has to get hot first.) and is built very well, couldn't I line the inside with chimney mortar to eliminate oxidation? and how do those super thin barrels survive the burn?
You could line your J-tube with castable refractory cement, but it would need to be at least 1" thick to have enough strength to stay in place on the sides and especially roof. I do't know if chimney cement has enough high-temperature capacity to last in the hottest parts. Lining the 10" feed and riser with 1" and a bit of castable would actually make a properly sized 8" system (sizes are typically referred to in diameters, and 7 x 7 1/4 or so is equivalent to 8" diameter). The 8" burn tunnel would have to be replaced, though. Steel, even heavy structural steel, will be destroyed faster than you would think in the temperatures and atmosphere of the combustion zone. The barrel will survive for decades because it sees only heat, after the combustion is complete, and there are no reactive gases there.
Philip Baldwin : I am not sure exactly what you mean when you wrote about ''Chimney mortar'' but most of these Dry Rockhard! Their expansion rates will be different
than the metal ! I expect that they will soon crack, and fall apart. Refractory Cement is kinda $pendy and I am very sure of failure of this material too! The best use of
a Refractory Cement in a Rocket Mass HeaterRMH Build is for glueing broken Bricks back together !
These materials Are not insulating !
Actually counter-intuitively, Rusting is not even close to the reason that Iron / Steel Metals fail ! !!! A quick google search for '' High Temperature Hydrogen Attack '',
or Hydrogen and Steam Embrittlement Will help understand the Fate of Iron / Steel metal in those locations.
A large part of the difference between the metal core of your Rocket and the barrel, is the barrel will only occasionally see 1,000ºf -not the 1,600ºF and above that you
can expect from its core !
The Barrels Heat Exchanger acts exactly like the Heat Exchanger within the " Blower cabinet '' of any of the Fossil Fuel Fired Forced-air Furnace. Both are made of very
similar Ductile Steel, All F.F.F.F-a.Furnaces Heat exchangers use a Thinner gage ductile steel than even the lightest Barrels/Drum ! The furnaces Heat exchanger usually
Gets a 20 year warrantee !
Hope this is timely, and you find it useful. For the Good of the Craft ! Big AL
Success has a Thousand Fathers , Failure is an Orphan
LOOK AT THE " SIMILAR THREADS " BELOW !
posted 4 years ago
This sucks. Thanks for info.
posted 4 years ago
So is firebrick the only suitable rocket mass heater material ? The sorry part is it works beautifully. It weighs about 300lbs stick welded by union pipefitters, a work of art!.......My heart is as broken as my Rocket mass dreams.
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''