Carpet, Wood Chips, Asphalt Shingles, coal, rubber tires ect..... expirements

[Seyiwmz]

I was wondering if anybody practices burning fuels other than solid wood? I've tried these, and they work decent until my stove reaches high temp. Without storage, I can't sustain a hard burn to finish off the alternate fuels completely. The coal left me with clinker, the rubber left me with toxic smoke. I'm thinking if the stove could sustain the high fire, I wouldn't have had any problems. It's to bad, because I have access to an endless supply of almost all rubber tires without wires. (Late model race car tires). Just wondering out loud......

 

[Eric Johnson]

You might try mixing wood chips in with shredded tires. That's what some papermills do to generate steam and electricity. Or pellets. You'd have to experiment to get a mixture that burns clean, but you might be able to do it. Seems to me that if you can get the rubber (or neoprene or whatever it is) to burn cleanly, then it's no worse than burning oil or coal. On the other hand, there might be toxic emissions that would survive the fire, in that case it's probably not a very good idea. But 2,000 degrees is pretty hot. I'd also be worried about CO.

 

[Seyiwmz]

Well, what I've done is usually throw a piece of carpet or rubber in with the wood. Not very big pieces, probably about the size of a paper plate. It's makes for a roaring flame blast. Try small pieces.

 

[Eric Johnson]

Does it smoke?

 

[Seyiwmz]

Doesn't smoke in the quanities described if the fans are blowing good. If it's idle, then you can get that residual smell from the rubber cause it ain't burning good. That's why I'd like a storage vessel to allow a longer hard burn cycle.

 

[webbie]

I'm glad I don't like downwind of you, Sey.....

No smoke does not mean that MANY poisons are not present. Industrial users can design around that stuff and monitor it, a home user cannot. Who the heck knows what chemicals are in that chit??

I say "Don't do it".....

Besides, it might eat away at your steel or chimney in unknown way.

 

[Jim Post]

Interesting, I won't even knowingly burn wood with nails in it....something I heard about the zinc in nails being hard on chimneys. I look at wood burning as being a natural process but carpet, shingles, and manmade materials burning is very un-natural.

 

[Seyiwmz]

Craig, I live down wind of a paper-mill, so that would give you 2 reasons not to live downwind of me. I know they've tried expirements with burning tires, but never had any real success. Instead, they burn thousands of tons of coal, natural gas, wood waste, and black liqour. Their industrial design only goes so far as to what's cheap enough to get by with. Needless to say, i don't have much faith in their industrial design. My main concern is breaking away from the un-natural price of propane. $2.70 a gallon is not good.

 

[Nofossil]

I'm stretching the limits of my chemistry knowledge here, but this is my take on it:

Wood, paper, bark, grass, fuel oil, and most plastics are made up of hydrogen, carbon, and oxygen. Not much of any other elements, and most of the trace elements still combine with oxygen to give you flue gases that are pretty harmless. If you have a good secondary combustion going, your flue gases are CO2, H2O, and N2 with only traces of anything else.

When you throw in materials that contain a lot of sulfur or metals (pigments, for instance) then your flue gases may contain SO2 and various metal compounds that aren't as nice.

As I learned early, there are no toxic chemicals, only toxic doses. In small enough quantities, anything is safe. The trick is having an idea what the safe quantities are. No bad smells is probably a reasonable first approximation for the compunds we're talking about.

 

[pdboilermaker]

Interesting, I won't even knowingly burn wood with nails in it....something I heard about the zinc in nails being hard on chimneys. I look at wood burning as being a natural process but carpet, shingles, and manmade materials burning is very un-natural.

The other option is the stuff goes into a landfill somewhere. It can leach into the soil and contaminate water. I say BURN IT, at least that way you are recycling it. One mans trash is another mans heat

 

[webbie]

Are you telling me that plastics and tires don't have bad stuff in them when burned at relatively low temps? I would need to hear that from additional engineers and chem majors!

I used to burn the plastic off my romex in a barrel and, wow, one whiff of that almost knocked me down! I never did that again. I think they do it chemically and/or with high temps when you turn it in to the scrap yard.

In general, I don't approve of "open burning" because someone downwind ends up breathing it. Tires can be recycled, ground up for all kinds of things...including clean burning in special burners. Plastics can be made into treks decking and many other things.

Nah, I'm old school......keeping it clean.

 

[Detector$]

Burning PVC gives off tons of hydrochloric acid, ABS gives off even nastier stuff.
The local fire marshal won't even allow you to install PVC wire in a plenum space in a building due to the harmful gases that would be distributed to the rest of the building. This is a bad idea, wood is good.... Sounds like a recipe for cancer to me

 

[pbvermont]

I echo Detecto$ comments, as somebody "downwind". Aren't there a few others?

 

[Nofossil]

Are you telling me that plastics and tires don't have bad stuff in them when burned at relatively low temps? I would need to hear that from additional engineers and chem majors!

I used to burn the plastic off my romex in a barrel and, wow, one whiff of that almost knocked me down! I never did that again. I think they do it chemically and/or with high temps when you turn it in to the scrap yard.

In general, I don't approve of "open burning" because someone downwind ends up breathing it. Tires can be recycled, ground up for all kinds of things...including clean burning in special burners. Plastics can be made into treks decking and many other things.

Nah, I'm old school......keeping it clean.

I would tend to agree, but it's a totally legitimate question. We're not talking open burning, we're talking about a combustion process with extremely high temperatures and abundant oxygen (lambda greater than 1.5, for most gasification boilers).

Most plastics are pure hydrocarbons. PET (drink bottles) for instance is just carbon, hydrogen, and oxygen. With high enough temperatures and a long enough reaction time, it will reduce to CO2 and H2O. I expect that a gasification boiler would burn moderate amounts of PET with no toxic emissions.

As I mentioned in an earlier post, rubber and other compounds may contain sulfur, metals, or other chemicals (chlorine comes to mind) that do not reduce to harmless compounds. Sulfur reduces to SO2, which then combines with the water vapor to produce H2SO4 - sulfuric acid.

I'm totally behind the idea of learning what works rather than assuming it's dangerous just because we don't understand it.

I'd love to see posts from someone with more chemistry than I have.

 

[heaterman]

Toxic emissions aside, you do realize that burning crap like that will void your warranty. .........Don't you? Call the manufacturer of your equipment and check it out before you throw any of that in your boiler................

And we wonder why wood burners are coming under scrutiny for polluting the air, water and ground.

 

[webbie]

So it will "just happen by accident" that some outdoor wood boiler is burning at 2000 degree plus (or whatever the temp required is) to break down these things?

Nah.

I am about 95% plus sure that we will discredit this idea - but, hey, I'll wait until we get to 100% .....meantime 85 is enough for me to tell folks that by burning that chit, they are sleeping with the enemy (Burning Issues). In fact, I'll bet there are here lifting these threads so they can raise more money!

I'm "green" first and biomass second. I don't see "incinerator" anywhere in my world view. I'd bury it or recycle it first.....

 

[Nofossil]

So it will "just happen by accident" that some outdoor wood boiler is burning at 2000 degree plus (or whatever the temp required is) to break down these things?

The picture and description seem to be a gasifier, which would reach and sustain these temperatures, and would provide a combustion environment vastly different than an OWB or conventional wood stove.

Nah.

I am about 95% plus sure that we will discredit this idea - but, hey, I'll wait until we get to 100% .....meantime 85 is enough for me to tell folks that by burning that chit, they are sleeping with the enemy (Burning Issues). In fact, I'll bet there are here lifting these threads so they can raise more money!

I'm "green" first and biomass second. I don't see "incinerator" anywhere in my world view. I'd bury it or recycle it first.....

I'm quite sure that most of the items described should never go near a wood furnace, and I've described why. I'm not sure that a blanket dismissal is justified, and I've described why.

My assumption is that the purpose of the forum is to add to the sum of our knowledge. That means that hopefully all of us have the opportunity to learn something that we didn't already know. I hope I've helped explain why rubber would be bad. It appears to me that some plastics might burn cleaner than wood. I don't know for sure that's true, but it wouldn't be at all surprising based on the chemicals involved. If that's the case, then burning makes more sense and is far greener than burying it at the very least.

Sometimes what we know is true just ain't so. This could be one of those times.

 

[TMonter]

I've seen tire chips mixed with wood burned before but you have to remember you have to have a hot fire with well distributed air which is something you're not going to get in a small boiler. You also don't have the thermal mass to deal with swings that come along and can make said chips put off some nasty emissions.

I would completely avoid any carpet, plastics or similar materials because of dioxins. You need temperatures 2500+ to destroy dioxins and you simply cannot get that in the OWB on the market. We ran an alternative fuels boiler for 8 years for Dupont and in order to stay in compliance we had continuous monitoring of temperature and variable combustion air zones to keep the boiler in compliance (We were burning PET, ground up x-ray film, and wood).

I'd say unless the manufacturer claims the ability to burn Tire chips with low emissions, they are something to be avoided.

Good article on Tire Combustion:

(broken link removed to http://www.epa.gov/ttn/catc/dir1/tire_eng.pdf)

 

[Eric Johnson]

The guy has an EKO gasifier, not an OWB. Big difference.

 

[Seyiwmz]

For all the non-believers, I assume that your running a conventional OWB. So, yes I would agree to stay away from anything but wood. I run an EKO 40 Gasification boiler and I intended this thread to be aimed at other gasifiers out there. I have gasified small pieces of carpet as well as small quantities of shingles, and coal. I don't get smoke when boiler is under high fire conditions, which would be the only time I'd try it. Sorry for any confusion created. Nonetheless, I think some of the "scrap" resources out there can be a utilized for the benefit of many. There is so much construction waste, mainly shingles going into our landfills. Too bad we can't use that for homeowner fuel source. I haven't perfected the process yet of burning it, but continue to expirement. Hopefully others will give it a shot and post their results. Thank you for your ides/opinions so far. Seyiwmz

 

[webbie]

No smoke does not mean no dioxins, etc.

I would ask someone to put a thermocouple in their gasifier and tell me what temp the stuff is burning at.
I doubt it is ever above 2000 and probably lower.

I'm not doubting that anyone "gasified" 80% or 90% of the junk in this "junk", but the other 10% is filling our lungs.

 

[webbie]

BTW, Tmont is a combustion engineer who has vast experience with this stuff - so anyone that disputes his info better have a bit more to stand on than "no smoke" or "gasifier"....

My outlook (and therefore Hearth.com "unofficial" outlook)......is that this is bad for our industry, reputation, environment and perhaps your unit and your family and neighbors. That brings up enough questions for me to take the "conservative" route.

 

[TMonter]

The guy has an EKO gasifier, not an OWB. Big difference.

It doesn't change the fact that the primary combustion zone after the gasification isn't going to be consistently hot enough to burn all of the nasties off.

My experience with small units is that you cannot reliably burn fuels with contaminants in smaller boilers because of three things:

1) Average temperature due to thermal mass (Small boilers have almost no thermal mass)

2) Lack of sophisticated combustion controls.

3) No consistent fuel feed to keep temperatures up

 

[Nofossil]

No smoke does not mean no dioxins, etc.

I would ask someone to put a thermocouple in their gasifier and tell me what temp the stuff is burning at.
I doubt it is ever above 2000 and probably lower.

See attached image. Combustion temp is the magenta line, divided by 10 to fit on the graph. Instrumentation is Omega inconel-jacketed high temperature thermocouple and Omega thermocouple signal conditioner.

I'm not doubting that anyone "gasified" 80% or 90% of the junk in this "junk", but the other 10% is filling our lungs.

If you start with fuel that only has carbon, hydrogen, and oxygen in it and it has time and temperature enough to fully react, I think you only get CO2 and water. I completely agree that fuels with heavy metals, chlorine, sulfur, and other noxious chemicals should not be burned. That includes rubber, and I've said that from my very first post.

That also includes PVC and many other compounds. That does not include all plastics or all non-wood potential fuels. I'd like to learn what can be burned safely as well as what can't, and I'd like to learn it based on facts and actual knowledge.

 

[TMonter]

If you start with fuel that only has carbon, hydrogen, and oxygen in it and it has time and temperature enough to fully react, I think you only get CO2 and water. I completely agree that fuels with heavy metals, chlorine, sulfur, and other noxious chemicals should not be burned. That includes rubber, and I’ve said that from my very first post.

Do you have the 1.5 second residence time at temperature needed to burn the compounds formed off? That is another problem with small boilers.