Wood burning and aluminum cans

[eeprom]

Hello,
I have been told that when burning wood fuel, adding a few aluminum cans to the fire would remove some or all of the creosote from the stack. Has anyone here ever heard of this? Is this true? What is the chemistry behind this?

thanks

 

[rmw]

That is a new one on me. And, I have burnt a lot of wood, professinally and personally. At home, I kept creosote out of the stack by burning only seasoned wood; never green. Professionally, green (pine) wood was principally all that was burned, but creosote in the stack was never a problem. Smoke, sure, creosote, no.

rmw

 

[eeprom]

I work on wood fired boilers for a living, and I have never heard of this either. The reason I am asking is that my mother recently bought a wood burner for her house, and she has been told by several other owners of wood burners that burning one aluminum can a week will eliminate all/most creosote. I just cannot imagine that the Al would bond to the carbon.

 

[chicopee]

Would you need to have finely shredded Aluminum to entirely burn? Don't know about the chemistry though.

 

[rmw]

Is Aluminum combustable? In the temperatures of most wood fires wouldn't it just melt? Are there any alloying elements that would come off and give the stated benefit? I've had contact with Al recycling and there is a lot of dross that comes to the surface. Would that stuff going up the chimney cause any reaction with the creosote, and would there be enough from a single can to matter?

Interesting topic, but I can't get my mind around it with respect to what I already know about the individual aspects of the process.

rmw

 

[eeprom]

I would assume a contained fire like that in a small wood burner would probably reach a temperature of 1500 - 2000 F, depending on air input. This is enough to melt the aluminum. The wood has C, H2, O2, N2, and S. >90% of the wood mass is C, O2, and H2. I can see how O2 would react, but the creosote is mostly carbon. How does Al react with C, or does Al act as a catalyst which improves the combustion? If you google this idea of putting Al in a wood fire, it seems a lot of people believe in this.

 

[rmw]

My first comment would be that I wonder if they also believe in the magnet on the gas line trick for your car.

That said, doing a little reading I see Mg as a precipitation hardening agent for Al, and I recognize Mg as a major constituent of fuel additives for heavy oil fuels that prevents both sludging of the fuel in the storage tank, and has beneficial effects downstream of the furnace by affecting the ash characteristics.

But, I am grasping at straws here I feel.

I have plenty of experience with steel in wood furnaces in the form of tire tread steel from scrap tire rubber burned as a supplement to wood in wood fired boilers, but not Al. Some of the zincs and things that were plated on the steel for corrosion protection were real problem makers farther downstream in the boiler and scrubber as I remember.

rmw

 

[eeprom]

I also suspect that this may be some sort of urban/rural legend. The following is a thread from a non-technical site on wood stoves. It appears that someone is claiming that the aluminum bonds to the steel of the stack. That bond breaks the existing bond of creosote? I don't know.



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If you put 8 or 10 aluminum pop cans in your stove while it's hot ,it will lossen all the crusty stuff out of your stove pipe.Works better than a steel brush .. Some of the crusty stuff that falls loose may get stuck in the elbow sections and may need removin.

-- Jesus Bob (heavens@inn.com), December 01, 2002.

I'm really curious about that aluminum can idea. We have an antique wood cookstove and would like to keep the chimney (metalbestos pipe) as clean as possible. Would the soda cans work in this stove? How many should we use? Are there any other poisonous fumes released during the heating of the cans?

-- Marcia (HrMr@webtv.net), December 01, 2002.

Marcia , I think it would work in any stove. I've never seen a metalbestos stove pipe so I wouldn't know if it would clean the pipe ? It's a chemical reaction between the 2 different metals ( aluminum can and steel stove pipe ) that causes the creosote ( crusty stuff ) to flake and fall out of the pipe. I used 8 cans and let them totally burn or disolve in the hot stove. A day or 2 latter when the stove was out ,I seperated an elbow section of the stove pipe and all the crusty stuff had come loose and was in the elbow and was emptied.

As far as poisonous fumes being released during the heating of the cans , it's aluminum. I throw the cans in when the fire is real hot and the next time I need to load the stove with wood I don't notice the fumes. The fumes should go up the stove pipe.As far as enviormental friendly , it's a poor mans or ( el cheapos ) way of keeping the stove pipes clean.

I did wonder if the chemical reaction of the 2 metals would harm the steel of the wood stove in the long run .I still don't know if it's bad for the stove .But at least the draw is good and I don't have to worry about a fire in the stove pipe.

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[macmet]

I do not have my textbooks in front of me, but if the oxidation of aluminum is exothermic perhaps the temperature is raised allowing the creosote to complete its combustion?

It seems like a weird coincident that refractory materials have high levels of aluminum oxide in them. Maybe somehow related to this concept?

This is interesting idea though. I've never heard of it before.

 

[davefitz]

sounds like the 10 cans were full of beer prior to the consideration of throwing their empties into the fire.

Not sure about wood burners, but aluminum cans have alsways been a problem with municipal solid waste incinerators and fluid bed boilers. The aluminum melts and plugs up the grid plate and nozzles, unless a suitable header-style air distribution style system is used.

You may have noticed on airplane flights that the stewardesses always put the aluminum cans in a different bag than the combustible garbage bags. Thants because the airlines have signed agreements with discrete MSW incinerators, and they absolutely may not have any aluminum cans fed to the incinerator.

 

[rmw]

And to think... I always thought it was because the stewardesses were having to supplement their income selling Aluminum cans.

On a serious note, the mental picture I have of aluminim cans on some of the grates that I have seen is their melting and plugging the air ports.

rmw