vertical gravity feed pellet burner????

[GoVertical]

Greetings, started a new project. I am hoping it will help reduce the heating bill. It is based on the rocket stove. I would like to configure it as a vertical gravity feed pellet burner.

As a rocket stove it works great, clean burn, no smoke. When I add pellets the grate fills and the fire dies and starts to smoke. Is there a design that uses just the natural draft from the fire. I would prefer not to add any fans.

Burn chamber is a 4 inch Tee within a 8 inch Tee.

If anyone has any ideas what the grate should look like please let me know.

Works well for burning junk mail. Cheers

[wooferhound]

Now all you need to do is sign up on plenty of Mailing Lists
Then build an automatic Junk Mail feeder . . .

[ghurd]

I am curious what the permanent burn chamber will be made of.

If you could figure out the Automatic Junk Mail feeder,
I could crank my thermostat to 95F!
G-

[12AX7]

Hi..

I don't think you'll have much luck burning pellets without forced air (a fan).

Every pellet stove I've looked at (and I've looked at a bunch) work with a  fan pushing air into the burn chamber (the burn chamber is pressurized).
The fan is always interlocked to the door,  so when the door is opened no hot embers are blown into the room.
It's a delicate balancing act, between the pellet feed, the draft pushed through the burn chamber and extracting the heat.

You have two major problems, the first being "gravity feed"  and the second not wanting a fan.
I can't think of a way to gravity feed without the risk of fire backing up into your pellet storage.
You can't take the heat away from the burn too soon or else the fire goes out.
I "mocked up"  a couple of stove ideas,  another problem you might run into is that galvanized stove pipe can't take too much heat before you start baking off the zinc, releasing nasty gas into your room.


I can't recall who,  but there was a thread started (I believe it was a corn stove but it's the same thing) here a while ago..  maybe search for it.

ax7

[GoVertical]

Greetings, using some tin cans to experiment with and inspired from some video's on YouTube I made a up draft gasifier pellet stove. I used vertical fins instead of holes for the grate and added a top combustion chamber.

The vertical fins allowed for increased air flow and prevented the embers from accumulating in the burn chamber. The second combustion chamber retained the heat creating an acceleration of gasification and  increased up draft showing no need for a fan.

Used cooking oil was used as a accelerant and the fire was started with a butane torch. There was a small amount of smoke produced at the beginning, then yellow followed by blue flames. Burn time for a ¼ cup of pellets was approximately 15 to 20 minutes with a complete burn to ash.

Results justify fabrication using stainless steel. Cheers.   



http://www.youtube.com/watch?v=7EoQoqJuAqo

[tomtank]

There are some folks on eBay who are selling vertically fed pellet stoves.

The dilemma is that wood as a fuel has oxygen in it and it can burn back up the fuel tube.
This is why pellet stoves are using augers to feed the fuel to the fire, to maintain a fire break.

That being said, it is worth trying. Wood burning is all about carburetion. Pellets do this a lot better.

[JW]

One thing thats nice about Otherpower, is that there's always somebody up to something.

When It comes to pellet burners im probably that guy.

I like the mention of a safety interlock with regards to any combustion chamber door.

Im going to add some video that shows these type of systems. Ive gone pretty far with design, even to go so far as to file a utility patent on my design. Such things are secondary, Im very open to the idea of issuing serial numbers and such, once I get a better idea of how the patent is going to play thru, then things can be worked out, so costs are incidental, and made burners can be resold with no limitations.

This pellet burner uses both natural and forced convection, hence is named "hybrid convection burner".

Natural convention does not need a fan, forced convection does. I will generally start my burner with natural convection. (no fan) After its running pretty good, the forced convection takes over for the higher fuel feed rates (using an auger) and maximum output.

Here's the video links
http://www.youtube.com/watch?v=IKDSX3lMasw
http://www.flashsteamvideo.com/play/Main_Category/Corn_Burner_10

This link shows some construction details,
http://www.flashsteam.com/Corn_Burners.htm
 the construction of the unit is based on recycled refrigeration tanks, or propane tanks. When you use the overlaping construction it increases the convection airflow, by increasing the surface area, giving the same or better results than a very tall chiminy, for producing a drought. The auger I use is powered from a 12 volt battery. The videos show a manual feed unit(no auger).

JW

[JW]

Id, like to add something here, I dont mind if somebody builds one of these for personal use, just dont go into mass production. Generally the serial number would cost between 50 and 75 bucks.

The natual convection part (made from the recycled tanks) is pretty easy to construct, the combustion chamber and afterburner unit are a little more involved to construct.

jw

[JW]

Something Additional,

Once a patent is mentioned most people visulize some dude trying to extact a bunch of money, etc,etc.

There are several feature's that combine to make my invention. One of which I have the privilege of potentially putting out there in the public domain.

Im speaking of something called (generic term) "Convection Chimney"

Im willing to post some drawings and descriptions,(in this thread) so that if one of the users wants to make a "wiki" entry, I would be willing to oblige.

I really dont see the harm in this, as its only one component of my invention, but since its  a "convection chimney" and is outlined in my claims(with different wording), widespread manufacturing is limited. But this is not intended to harm the DIY'er, and just the convection chimney by itself should enable Go Vertical atleast get wood pellets to burn (besides paper).
 
In general a DIYer will never re-sell there burner, so a serial number is not needed... Even as such, convection chimney by itself would not even apply for a serial number. I can give advice as to rust proofing(coatings). But mass production of convection chimney's is/are limited, for the DIYer this does not apply, unless there is in intention to re-sell.
JW

[ETech]

I thought I remembered that welding galvanized metal produced very toxic gasses.

If you using galvanized sheet stock I would looking this to prevent being sent to the hospital.

There was a report of one welder dieing from welding fumes ( I don't have the link here at work).

It may only be related to the temperature, but it is worth looking into.

Maybe one of the metal smiths here can chime in.

ETech

[JW]

This is one of the reasons I mentioned "rust proofing-coatings"

At this stage there is no risk of potential harm to Go Vertical, he's not even reaching temps to 1,500*f with paper-balls.

However, if a spike in temperature were to occur, the galvanized would turn a green dusty color and become toxic...

The coatings I recommend are aluminum based, not unlike the coatings used on a colman lantern. As a rule of thumb, temps over 2,500*f are to be avoided since that will produce elevated levels of NOX emissions.

JW

[GoVertical]

Greetings, first attempt at gravity auto feed pellet burner. The experiment revealed that the fire backup into the supply tube and stopped the pellets from reaching the combustion chamber as others had predicted.

I have to move location of supply away from combustion chamber, increase the diameter and slope of the supply tube, and try lighting the fire from below the grate. Burn time approximately 35 minutes. The finned grate performed well.
   
http://www.youtube.com/watch?v=Zd7l5gagp3E

[GoVertical]

I thought I remembered that welding galvanized metal produced very toxic gasses.

If you using galvanized sheet stock I would looking this to prevent being sent to the hospital.

There was a report of one welder dieing from welding fumes ( I don't have the link here at work).

It may only be related to the temperature, but it is worth looking into.

Maybe one of the metal smiths here can chime in.

ETech

Greetings, thanks for heads up about the toxic fumes. If I can get it work I plan on fabricating the combustion chamber out of stainless steel or fire brick. Thanks again and best regards.

[JW]

I liked your video, gives a better idea of what you are doing.

Cheers 

[dnix71]

I've gotten sick from careless welding of galvanized. I don't smoke and am otherwise fairly healthy. You need to keep the fumes away from you, but in this case I don't think it's possible.

http://www.anvilfire.com/iForge/tutor/safety3/index.htm   This is the link ETech mentioned.

Even if you switch to stainless, you will need to beware of chromium and nickel fumes. I've seen stainless rust after using it to barbeque. A man I know who built fuel storage tanks for the military made a 55 gallon drum barbeque grill from cold rolled stainless plate thinking it wouldn't rust. It didn't rust until we used it to cook. The used scrap has still not rusted.

http://www.ehow.com/list_7463537_stainless-welding-hazards.html

Your burner needs to be seasoned by fire outdoors somewhere before using it inside.

[ghurd]

Am I the only one concerned about the thin metal burn chamber?
G-

[JW]

I think he's just experimenting, to gain a better idea of a future design.

One other thing, stainless is pretty expensive. I dont use it all that much, but for things like hinges its good. Steel can be used without fear of major rust after fireing, but you must sandblast it (all sides) then coat it with something simular to this- http://www.m-r-c.co.il/Media/Uploads/254SPEC.pdf Its called duralco 200 made by cotronics

JW

[Ungrounded Lightning Rod]

Pellet stoves have two blasts of air:
 - One into the pellet pile, to keep it burning and sending out smoke and small flames.
 - Another into the smoke just above the pellet pile, which burns the smoke.

I don't see any inherent reason why you couldn't force the air circulation by creating a small amount of vacuum in the combustion chamber via the draw of a chimney.  You'll just need a tall enough one to pump the air adequately.

You also want the chamber a bit lower pressure than the surrounds so any leaks are inward.  And counter-current from bringing fresh combustion air down around the central chimney exhaust pipe will keep the pipe relatively cool (especially on the outside where it's a fire hazard against the building structure), preheat the combustion air, and scavenge much of the heat in the chimney once it's done its pumping work.  This is pretty standard on some furnace designs.

[GoVertical]

http://www.youtube.com/watch?v=5CcD_4x_SCQ

Greetings, I found the solution for preventing the smoke and fire from rising up into feed hopper. I placed air holes only on the side of the combustion chamber with the feed hopper . The video shows the smoke and flames being pushed away from the pellet feed hopper. Thanks for all the help and best regards.

[Ungrounded Lightning Rod]

http://www.youtube.com/watch?v=5CcD_4x_SCQ

Greetings, I found the solution for preventing the smoke and fire from rising up into feed hopper. I placed air holes only on the side of the combustion chamber with the feed hopper . The video shows the smoke and flames being pushed away from the pellet feed hopper. Thanks for all the help and best regards.

You'll need to be careful with your chimney and draft arrangement so you don't get wind down the chimney blowing the fire toward the feed occasionally.  (Once is all it takes.)

I'd also put an airtight cover on the pellet hopper to retard a fire if it gets going in there and to minimize chimney effect in the feed tube if a fire gets going at its base..

[GoVertical]

Greetings, I found a configuration that prevents smoke and flame from entering the pellet feed tube. By adding a screen around the exhaust and adding a vertical fin within the combustion chamber creates a very strong up draft. The combustion chamber also has two grates, one approximately a 1 inch below the other .  The video shows the affect when the chimney screen is removed. I still have to add the fuel hopper and make it air tight as suggested, then I will be able to test burn duration.

http://www.youtube.com/watch?v=nfoDyKCA3xs

[tomtank]

 Saw this on Ebay.
Seems like a decent design.

http://cgi.ebay.com/Pellet-Burner-Large-4-Model-Riley-Stoves-/350201310217?pt=LH_DefaultDomain_0&hash=item51899fec09

Check out his other auctions to see how it goes together.

[Tritium]

Saw this on Ebay.
Seems like a decent design.

http://cgi.ebay.com/Pellet-Burner-Large-4-Model-Riley-Stoves-/350201310217?pt=LH_DefaultDomain_0&hash=item51899fec09

Check out his other auctions to see how it goes together.

Seems like his price is just short of total insanity for a stove "part". (stove not included)

Thurmond

[12AX7]

Hello..

I've been watching your progress and I'm impressed!

However...  I'd like to mention/warn you of a potential problem in respect to the pellet feed into the burn chamber.

I've been involved with high speed packaging for many years, and have worked with a number of "products",  and their behavior.
A very common problem with transferring from one "hopper" to another is something called "bridging", "worm holing" and "head pressure".

Just about anytime you have a "necking" down or a narrowing of funnel walls there will be the opportunity for the pellets to "cluster" in such a way that will cause them to "bridge" and stop the natural flow.
This problem is almost never seen when there is a minimal amount of "head pressure",   in this case when there's only a few handfuls of pellets pushing into the burn chamber.  It's likely that once you have a large volume/weight pushing that there will be times when the pellets will bridge, stopping the flow or  preventing a "consistent" flow of pellets.   This could result in starvation followed by "forced fed". 

With your present set up ( I understand that it's a test/mock up) it's possible that these same issues could enable the fire to back up into the pellet hopper.

I'm not telling you that this WILL happen,  but you know "Murphy's law".

Good luck!

ax7

[GoVertical]

http://www.youtube.com/watch?v=HTUxarUvb2E

Greetings, project moving forward.
Stainless steel elbow used as heat exchanger. I still have to insulate input and output vents and add a plenum to preheat the vent air to increase performance.  Front panel will also be installed.
2 foot by 6 inch pellet hopper holds ½ a 40 pound bag of pellets and system burns 8 hours and requires no attendance. 

[12AX7]

Hello!

I watched the video a couple of time and I don't understand/see from where the pellets are being fed from.

The H style chimney,  is it to increase the draft?

Looks like your weather is not helping things! 

ax7
Mark

[GoVertical]

Greetings, the pellet hopper is on the back left corner. The H chimney just prevents back draft from the wind. Inside the box, the round aluminum flex tubes are the air vents and the pellet feed tube runs to the bottom of the combustion chamber. I had to cover it with a piece of shinny aluminum to keep the pellets in the feed tube. I was able measure the air temp and found air vent input temp was 16 degrees F and air vent out was 120 degrees.  I plan on adding a plenum on the top to preheat the air before the stainless steel elbow and insulate the air vents, hopefully this will improve performance. The biggest challenge at this point is to transfer as much heat to the air inside the vents, the system needs a better heat exchanger.

[12AX7]

Hi..

Ran into this...   thought you like to take a look.

http://www.rileystovemfgco.com/pelletstoves.html

[GoVertical]

Greetings, thanks. I was unable to find any technical drawing of their design. I ended up making a bunch of prototypes using tin cans and stumbling across a configuration that appears to be very similar. I hope to have the vents installed at the shop today. Hopefully, once I insulate the duct work I will have some heat inside the building. 

http://www.youtube.com/watch?v=HTUxarUvb2E

[GoVertical]

http://www.youtube.com/watch?v=epGDmJciN0U

Greetings, after two days of testing my idea of using a stainless steel elbow as a heat exchanger and blowing the hot air into the shop does not work.  On the plus side the gravity feed pellet burner works very well. I did find that considerable heat is radiating from the top of the metal box housing the pellet burner. I am planning to add a plenum to the top of the housing and vent that into shop, hopefully this will recover more heat. If anyone has any ideas how I can improve heat recovery and transfer that heat into the shop please let me know. Best regards

[WindriderNM]

attach fins to the stove pipe

[GoVertical]

Heat Reclaimer concept drawing. Thanks for the fin idea.

[12AX7]

I've a couple of quick questions,  during operation is there a panel covering the opening? 
Is the flex hose (from and to the building) insulated?   

I'm sure your design change would improve the heat transfer/recovery, however I think that you will still loose a lot of heat up the stack and through the walls of the burn chamber.   

You might consider covering the entire stove with insulation. 

I don't know what your local codes are like,  but most places have a "minimum" distance that's required between a "structure" and a outside stove.

Here (in Wisconsin) our local codes require that a outdoor open flame (wood/pellet/corn/other) stove must be at least 25 feet away from the nearest structure.   I believe that this is the main reason why outdoor stoves are "boilers" where a water-glyco mix is used to transfer the heat into the buildings.

You should check with your home owners insurance company/agent and your local building/fire codes.