Rocket stove pellet modification

[zero]

I've been running out of the wood I scrapped from a large coax spool at Mohegan Sun so I decided it was time to start designing a pellet mod in earnest. The first attempt was a tin can with lots of holes hanging about 1.5" above the floor of the firebox. It would not sustain a burn for any length of time.

Thursday night I made a second attempt with a metal grate made from coat hangers. The first concept was to create a thin curtain of pellets in front of the horizontal burn tube. It worked better than the suspended can but again the flame would not spread, pellets did not drop in freely and it eventually died out.

However, with this metal grate I was able to slide it around in the firebox while it burned. What I quickly noted was how critical the position inside the firebox was. I then applied what I know about the venturi effect created by sticks in the firebox opening and realized I needed to emulate the process with my grate full of pellets. I opened the width to about 1.5", centered it front to back and bent the top corners to hang it 3/4" above the firebox floor. It was a complete success. The top of the tank ran at a constant temp of 520*F and the grate did not clog at all as I had feared.

The next step is to make a gravity feed wood pellet hopper mounted to the wall next to the stove. This should permit sustained burns many hours long without having to constantly tend to it. Stay tuned!

[icu4dzs]

I've been watching the evolution of this particular rocket heater.  I built a similar stove, (somewhat larger because of the available materials) and am up to #358 (?) regarding the most recent modification of the pellet "basket" wherein you made it less symmetrical.  I noticed however that you started out with a tin can full of holes. In the pellet stove I have in my living room, the "fire box" looks more like the "tin can" you used but significantly different metal.  Have you considered using something like that rather than the stainless steel rods? (1/4" stainless steel plate for instance?)
Have followed several of your projects.  Somehow lost track of the Muller motor. Was that a failure?
I'll publish my project here if that is OK. I used 6 X 6 SIZE,  3/8" steel tubing for the burn tunnel heat riser and fuel magazine but have been told by several that "metal is doomed".  Fortunately for me, I did not damage my "bell" which is an old water heater tank made of 3/32" steel.
Despite those who have told me the project will eventually fail because of the use of steel, I have had no signs of failure to date.  The EXTREME cold in this part of the country has made its use less than idea.  Even though I can achieve close to 700*F at the top of the bell, the shop size is too large to be overcome by the heat generation of the rocket heater.
But then I have "traveled from east to west and from west to east again in search of that which was lost".
Cheers
Saepe Expertus, Semper Fidelis, Fratres Aeterni   
Trim sends     
//BT//

[zero]

There are other reasons not to use only steel. You'll see. 

[Etherimos]

I'm about to embark on my construction of your magnificent rocket stove Zero. I've got a couple of questions for you though if you have a moment. How critical is it to get the inside chimney on the J-stove chamber directly centred in the stove? From what I've read about conventional rocket stoves, having the chimney inside offset simply produces more heat on one side and less on the other.

I don't think I'll be using the pellet modification right away, I seem to have a lot of firewood laying around, so I'll probably go at least one year with just that - but I'm eagerly looking forward to your experimentation results!

[zero]

First of all welcome!

Secondly, I can't say from personal experience because I haven't built any with offset risers but everything I've read agrees with your statement. The side with the greater gap gets higher percentage of exhaust gases so it stands to reason that side will be hottest. Can't wait to see your build!

Best,
Z

[Etherimos]

Hey Zero, I saw on your youtube channel that you broke 1000 degrees! Congrats!

Have you got any videos on the lighting process - I've got my stove done and I start to light the darn thing and it seems to work for a while but then it stops drawing and I'm trying to trouble shoot it Thought I would start with what is probably the easiest problem in the chain to fix - my lighting process!

thanks!

[zero]

A lot depends on what you're burning, sticks vs pellets. Can you describe your J-tube materials and dimensions? Flue pipe configuration? Pictures would be very helpful because honestly, mine starts to draw almost immediately.

[keithturtle]

Turtle here

I've put most of my recent focus on rocket stoves, with a view to provide cooking units that use refractory cores and old propane tanks as a main structural element.  Not much progress, but then, turtles ARE slow.

I've also done some stuff with mechanical wood choppers, simply an axe on a counterbalanced pivot and also something more elaborate.

Will post in coming weeks.  Good to be among friends

Turtle

[zero]

Welcome brother Turtle. Looking forward to what you cook up! 

[keithturtle]

Welcome brother Turtle. Looking forward to what you cook up! 

Finally made some progress, been real busy till now with the job at the mill.  Now with some time to burn, I hope to post some interesting stuff

Turtle