|
Post by satamax on Jan 26, 2012 11:59:40 GMT -8
Hi everybody!
Well, on another forum. A well respected man has stated temps of 2000 to 3000 degres, farenheight i'd think! That seems like an awfull lot. Well, he says metal rocket don't work. Mine kind of does. And i've seen few others. I know from my engineering school days, that there's several layers of gasses moving at different speeds in a tube, and that they slow and cool down towards the edges of the tube. I'm pretty sure i've read what others have said about rocket stoves, and that they don't burn the steel that easy.
What's your opinion on the subject? What temps have you measured?
Thanks a lot.
Max.
|
|
|
Post by canyon on Jan 26, 2012 13:17:35 GMT -8
The temps can be very high on 8" systems in particular and I am impressed by how fast the steel oxidizes in the lower heat riser where there is more turbulance/available o2 and high temps. With that experience I now lean towards refractories for the highest temp areas. I have not been testing temps in these zones yet so no empirical help from here on that. Peterburg may have some numbers for various designs?
|
|
|
Post by Donkey on Jan 26, 2012 18:00:08 GMT -8
I got no numbers either, but I have seen barrel tops and 1/4 inch steel plate glow cherry red. This suggests around 1500 at the top of the heat riser. This IS rare, normally these stoves don't get that hot at the barrel, normally you don't WANT it that way either. I see (black) metal stove pipe (in 8 inch stoves), on a regular basis, turn to melted crumbles. Though use black pipe, I get it from the dump and use it as a sort of expendable mold, to hold a pearlite/clay mix till it's dry and somewhat fired.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jan 27, 2012 2:32:10 GMT -8
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jan 27, 2012 3:18:59 GMT -8
|
|
|
Post by martinm on Jan 27, 2012 3:31:47 GMT -8
In regards with temps inside a heating stove: when looking at the flame/burning pattern it wouldbe beneficial to build the (rocket) stove following this pattern and applying the best environment for the flame: fire chamber - inner layer -average thickness,( with certain mass for t-inertia so it will help heavier wood pieces to burn) from dense firebricks/clay, outer layer - light cob, perlite / clay mix or in general very fire proof light insulation. heat riser -inner layer thinner firebricks/f.clay mix to provide for quick response, outer layer - as light as possible. then comes a heat exchanger - could be barrel or brick/ cob - depends on heating requirements, but generally adding mass with the distance away from the flame/ heat riser. ... all this cristalised few minutes ago when cleaning my improvised RSMH and looking to the pattern of ashes and creosote accumulation Peace and prosperity ! MM
|
|
hpmer
Full Member
Posts: 240
|
Post by hpmer on Jan 27, 2012 7:26:15 GMT -8
I got no numbers either, but I have seen barrel tops and 1/4 inch steel plate glow cherry red. This suggests around 1500 at the top of the heat riser. That's consistent with my stove as well. It's only a 6" and is a cooking stove. I have a thermometer at the top of the heat riser that only measures to 1000 F, but I can easily max it out so I'd guess 1100-1200F as top temp. Increase the stove size up to 8" and top temp would likely go up as well.
|
|
|
Post by satamax on Jan 27, 2012 8:32:18 GMT -8
Thanks a lot guys. Well, the next question which comes to my mind, do we realy need the hotest flame to burn everything. If we have a bit more air intake, than the ideal adibatic combustion, the gasses in the burn chamber and heat riser will somehow cool down. The thing would be to find the good compromise between proper burning through the burning lengh, and not too hot as not to melt things Since i'm a keen user of metal.
|
|
|
Post by pasto76 on Jan 27, 2012 16:15:25 GMT -8
my two cents as a structural ironworker and weldor; the "kindling" temp of mild steel is 1600 degrees. Thats the temp I need it to get to before I can cut it with an oxygen jet. It is also just before it starts to glow. So if it is glowing thats pretty Fing hot
|
|
|
Post by martinm on Jan 28, 2012 3:34:27 GMT -8
anyone with experience using glased steel exchaust pipes for the heat riser ? in Europe they are standart for stove fitting. Peace MM
|
|
|
Post by satamax on Jan 28, 2012 9:18:57 GMT -8
Hi Martin, you mean enameled stove pipe?
|
|
|
Post by peterberg on Jan 29, 2012 0:52:47 GMT -8
The temps can be very high on 8" systems in particular and I am impressed by how fast the steel oxidizes in the lower heat riser where there is more turbulance/available o2 and high temps. With that experience I now lean towards refractories for the highest temp areas. I have not been testing temps in these zones yet so no empirical help from here on that. Peterburg may have some numbers for various designs? No numbers either. But there's more to tell about whether or not a rocket stove will eat mild steel. Simply put, it's a combination of high temps, low CO and high O2 levels. We all do know by now, a rocket stove is able to generate very low CO levels. Subjected to high temps (1830 F and more) the oxygen is extracting carbon out of the steel, reducing it to rust. A great deal of spalling will occur, visible by dull grey flakes on top of the steel surface. Leave one of the conditions out and nothing disastrous will happen. For example, during testruns with the dustbin rocket all was well before I've insulated the lower half of the feed tube. The condition of high temp was absent so the steel could survive. With the added insulation however, it took about 10 hours of test runs to burn holes in the 1/8" sides (left and right) just above the very bottom of the tube. One could choose to leave out this insulation, of course. But it's good to know the version with the insu in place could obtain much, much better results.
|
|
|
Post by martinm on Jan 29, 2012 2:49:39 GMT -8
Hi Martin, you mean enameled stove pipe? Yes Satamax, I mean Enameled on both inside and outside exchaust pipe. I was palnning on using it as a inner tube for the heat riser but decided to go with buiding the core out of fireclay/sand. On regular stoves I have seen many times enameled pipes glowing red and no damage. My assumption is that enameled would be ok for a while , but once the enamel start cracking then ..... Cheers Martin
|
|
|
Post by leewaytoo on Feb 1, 2012 10:54:19 GMT -8
|
|
|
Post by erikweaver on Aug 2, 2015 7:09:55 GMT -8
Other threads on this site discuss this (I don't recall which one's, I've been re-reading everything again). Terra cotta doesn't hold up, and cracks pretty badly in the extreme heat (approx. 2,000 F range).
|
|