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Bio-briquettes for RMH

Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
Looking into bio-briquettes as a possible substitute for wood to burn, I came across a guy on YouTube who shaped his briquette specifically for his rocket stove. He shaped it like a donut. It fit snug into the rocket stove's feed tube. The hole in the middle allowed air to feed the fire, once the briquette was lit. His experiment used a small donut that wasn't very long and probably wouldn't burn any longer than twigs or sticks. But, it made me wonder about something.

If the briquettes were pressed into two foot long molds, with a hole in the center, would that allow a longer burn time between refueling?
Say you build a six foot, insulated feed tube on the rocket stove and put three of these two foot bio riquettes in it. Wouldn't that give you six feet of fuel for the fire to consume? (the feed tube would be insulated in the same way the flue is insulated in a rocket stove) The hole in the center should carry air through the briquettes to the fire at the end, which burns backwards in the tube.

Seems like that would give more burn time between refueling.

Am I wrong about this? Is there something I've overlooked or forgotten to consider?
Mark Livett


Joined: Nov 21, 2012
Posts: 56
This video http://www.youtube.com/watch?v=L1t6eD9Ijwc ?

Interesting question. If you are after a long burn time would you be able to extrude the briquettes into a rod and make pellets out of them? Then you could use a hopper full of pellets for a longer burn time.

I do like that little stove though!
tel jetson
steward

Joined: May 17, 2007
Posts: 3088
Location: woodland, washington
    
  53
a six foot insulated feed tube would be very difficult to get working. it would act as a chimney and draw air back through the system the wrong way. if you had a twenty foot heat riser, it might be made to work, but there would need to be some additional features to get it burning the right direction.


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Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
Mark, yes, bio-briquettes could easily be made into pellets. There is a machine that does exactly that, and very quickly. I'll have to look into pellet feeder devices to see if it will work for this purpose.

Tel, that's a good point. Maybe a fan to get things going in the right direction? Once things heat up in the flue, maybe the fan could be turned off. A fan might get the rocket stove up to heat quickly, reducing the start up time in which the RS smokes.

I want a longer burn time for a project I'm working on which might allow a rocket stove to produce enough electricity to power a home. I'm going to explain it in the rocket mass heater/stove section in the hope a few others get interested and also attempt it. It's going to be an open source project if other rocket stove/heater enthusiasts see value in it and give it a shot. I don't care who is first to accomplish it or who takes credit. Getting it done and spreading the word is all that is important.
tel jetson
steward

Joined: May 17, 2007
Posts: 3088
Location: woodland, washington
    
  53
Bill Bianchi wrote:
Tel, that's a good point. Maybe a fan to get things going in the right direction? Once things heat up in the flue, maybe the fan could be turned off. A fan might get the rocket stove up to heat quickly, reducing the start up time in which the RS smokes.


I don't think a fan would be adequate. supposing it did get going in the right direction, though, the draft of the heat riser would always be fighting the draft of the feed tube so it wouldn't ever be able to push through a long run of exhaust flue. I really don't think a tall feed tube is a workable solution to the problem of these things needing frequent attention.

don't give up on account of my pessimism, though.
Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
I won't give up. We've got minds, so we'll figure this out eventually.

Someone here mentioned a magazine feed system. That seems doable, though it would complicate the system. That is one option to explore.

The pellet system is another, though I'm not sure how to implement it and still get the high heat I need for my project.

If not a full 6 feet of bio-briquette tubes, then two feet would work so long as the riser is taller than that, which would be easy enough. That would still be better that shoving sticks into it every 15 minutes or so.

I'll probably need a fan on it anyway to get the heat I need. Since I'll be generating electricity anyway, the power consumption of the fan won't matter much.

BTW, I posted our project. It is a gasifier built into a rocket stove. The resulting producer gas will be fed to a generator. I think the thread is titled 'Rocket Stove Gasifier.'. It has a ton of advantages over standard wood gasifiers and I provided enough information necessary for anyone here to begin development on it.

Another project I'll tackle soon is a DIY Stirling with enough HP to generate a usable amount of electricity. It will also be powered by a rocket stove.

This is why I need a longer burn time between refueling. In either case, the stove will have to run 4 hours in order to charge a battery bank. If people are ever to adopt either technology, the fire will need to be more convienient to tend.
Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
Still dogging the issue of loading up for a long burn time between refueling. I might have an uncomplicated answer. If the idea is sound, gravity will pull new fuel into the rocket stove whenever the stove needs more fuel.

If I made the briquettes into balls, I could set up a track and roll them into the rocket stove. At the end of the track (lowest end) would be a stopper that allows the ball just inside the stove. The rest of the balls would be on the track behind the one at the end burning. When the one at the end turns to ash, the next one would roll in, already on fire. That's the theory so far.

For the air intake, we're pulling air in from up top, running it through pipes in the sand between the two walls, and into the stove through angled nozzles. We're trying this in an attempt to feed the stove preheated air. The nozzles are angled to encourage a cyclone effect in the flue. To keep the fire from climbing up the track from ball to ball, we would angle one of the nozzles to flow hot air from behind the lead ball.

What do you all think of that idea to load up a rocket stove for a long burn? Will the track of burnable bio-briquette balls work, do you think?
tel jetson
steward

Joined: May 17, 2007
Posts: 3088
Location: woodland, washington
    
  53
I think a sphere would be more difficult to make and a cylinder would roll just as well.

the nozzles sound overly complicated to me. they would nit draw on their own, so you would need to force air through them somehow. adding complexity in this instance likely reduces reliability. could be a fun engineering challenge, though.
Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
You might well be right about the nozzles. We'll fire it up next test to see how it does. Preheating the air should help to get more heat, in theory. We'll know more after we've tried it.
tel jetson
steward

Joined: May 17, 2007
Posts: 3088
Location: woodland, washington
    
  53
hot air is also less dense, so you'll need more of it to provide an equivalent amount of oxygen for combustion. if it works, you could end up with some pretty serious heat, but there are a lot of complications.
Jen Shrock
pollinator

Joined: Jan 25, 2013
Posts: 356
Location: NW Pennsylvania Zone 5B bordering on Zone 6
    
    8
I have been intrigued by the concept of RMH for quite some time but have not ventured into them. I also have a very big interest in using the RMH for electricity production. You mention feeding the stove for a longer period of time. Couldn't you, instead of the round balls that you mention, put small brickettes in a track that feeds into the stove, with the track itself extending beyond the feed tube so that you don't have to worry as much about the draft issue?


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Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
Hi, Jen.
I see what you mean with the track extending beyond the feed tube. That would solve the draft issue. We could even spring load the briquettes to ensure they "march" into the stove in an orderly fashion as the lead briquette turns to ash. Thank you for the input.

We'll see how using preheated air goes. If it doesnt work, we'll convert back to feeding air by the feed tube.

I am convinced the rocket stove is capable of generating producer gas, which will run a generator to supply electricity to a home.
Once we get our stove setup the way we want, progress toward that should come fast.
Yone' Ward


Joined: Feb 14, 2012
Posts: 135
Location: Springdale, WA USA - Cold Mediterranean Climate
I believe this string of videos will be useful to you. He's good at what he does and shows you what went wrong with his system. He ran his system for hours on end and as a result, probably put a decade's worth of wear and tear on his stove inside a season.


Just call me Uncle Rice.
17 years in a straw bale house.
Bill Bianchi


Joined: Mar 03, 2013
Posts: 226
    
    1
I've been looking at Mike Brown's 1 & 3 horse power steam engines. I'm aware that steam engines are a very hands-on way to generate electricity and they can be dangerous and that gasification is cheaper and easier. But, that said, I'm still interested in steam engines because I think they're cool. It's something I'd like to learn how to maintain and operate, then pass that knowledge to my children.. I'll have to look for a local steam club in my area.

Bio-briquettes look to be a sustainable fuel source for heating the boiler. Those briquettes could even be turned to charcoal first, especially if the waste heat from that process were used for home heating & hot water heating. Also, the charcoal can be gasified in a simple charcoal gasifier to run a gasoline generator for a backup to the steam engine, or vicaversa.

In any case, bio-briquettes could make a good alternative fuel source to wood, allowing those without wood resources to power their lives if they wish.
Amos Valenti


Joined: Mar 15, 2013
Posts: 52
Location: NE PA zone 6
    
    1
Hello, I make and burn my own biochar in the RMH. It started as an incidental thing but now I am exploring the options of using it more often. Our biochar is made from scraps of hard and soft woods and really seem to burn hot and for a long time. Apparently bio char can be made from any dry organic material but we have only used solid wood scraps.
 
 
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