Chelonian

Burning Off Coal Smoke In Chimney?

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I've been thinking quite a bit about ways to minimize exposure to coal smoke. Even when my chimney is working well, the smoke sometimes will still linger around in a cloud (the forge is outdoors), resulting in me breathing some in. I'd also rather NOT have a nasty cloud in the backyard, given the choice. Here's my idea, as I imagine it working in a perfect world:

Since my chimney is just a side draft from a tall piece of stovepipe, I could cut out a section and make a small hinged door somewhere in the middle of the chimney, and place a grate inside the pipe. Then, before lighting the coal in the forge, I could start a small wood fire on the grate in the middle of the chimney, and maintain it for the duration that I use the forge. Not only would this help with maintaining a strong draft, it would also burn off all the coal smoke that went up the chimney. Hopefully I explained that well enough to get the main points across.

Now the questions:

  • Has anyone tried anything similar to this?
  • Would the draft of the chimney make it difficult to keep the small wood fire going?
  • How "much" heat does it take to ignite coal smoke? Would just a small electric arc be sufficient? What about a candle? Perhaps some testing is in order.
  • Would this be dangerous to try?

I'm really interested to hear peoples thoughts about this. Thanks!

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If you are getting a lot of smoke once the fire is going, you are not maintaining the fire properly by adding green coal to the fire. The fire should consist of coke, that green coal has turned into around the outer edge of the fire then raked into the fire.

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I'm aware of that, and I have become decently good at keeping it to a minimum, but there is always still some. Especially on days with high atmospheric pressure and little wind, the smoke can still collect over time. Fire maintenance, while very important, wasn't really the intended topic of this thread... :ph34r:

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I'm sorry, I thought the topic was about eliminating the smoke. The best way to do that is not produce it in the first place. I don't think maintaining a wood fire in the stack would do much good. How high is the stack? Probably raising it would work better.

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Smoke is unburned volitals from the fuel. Start with a HOT fire from small sticks. Add a little coal at a time so it catches fire before you add more. This will burn most of the smoke produced as it forms coke.  As the fire gets HOT, add more fuel.  Always keep a small hole at the top of the fuel to allow the fire escape and help burn any smoke produced. The green new coal should go to the outside of the fire to form coke, then the coke should go to the fire to replace the fuel burned.  

Having a fire in the chimney seems to be more trouble than it is worth.  Just produce little or no smoke to begin with.

To eliminate smoke in your work area, build a better chimney. 10-12 inch diameter is recommended. Side draft is better than a hood. One of the easiest ways to increase the efficiency of the chimney is to add height to the stack. Check your chimney height to be 3-4 feet above anything within 10 feet of the chimney.  Even then you can add more height.  This does not eliminate the smoke it just gets it up and out of your way. You eliminate or reduce the smoke with fire maintenance.

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The chimney is 8" in diameter, and about 5.5' tall. It outputs the smoke at a height of about 8.5' above ground level. As I mentioned, the problem isn't usually that the chimney doesn't move the smoke, I think  it's more that the smoke settles back down again. I would add more height to the chimney, but I think that might make it blow over in the wind. There isn't anything within 10 feet that is above the chimney.

I guess I'm just pretty sensitive to the smoke. A small amount makes my throat scratchy and gives me a headache. Might just a box fan be more effective? Would there be some way to add a filter to it so that it captures the smoke particulates? Seems more far-fetched than the burning it off in the chimney, but I just thought I'd ask anyways.

Maybe I'll just end up going back to anthracite...

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Simple solution is do not inhale. (grin)

Heavy weather can cause smoke to stay in the area, or stay close to the ground. Local conditions can sometimes make this even worse. Lack of a breeze or wind, air inversion, etc and it could be a real problem if you are sensitive to the smoke.  Fire maintenance will not change the weather, just reduce the amount of smoke produced.

Under these conditions, do not fight it, mother nature always wins. Just go inside, get a lunch and a cold drink, and visit IForgeIron. Spend the time learning something new, or add new ideas to your notebook of things to do or try.  A lump of modeling clay will allow you to get physical with the ideas and concepts. It is a good way to work out problems, and practice before you use hot iron.

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So anyone aware of the system Weygers set up to run green coal smoke back into his handcrank blower and into the fire again?

It should be described in "The Complete Modern Blacksmith"

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2 hours ago, Glenn said:

Simple solution is do not inhale. (grin)

 

But then how do I blow the scale off my anvil? :rolleyes:

Thomas, I hadn't ever heard of him, but a similar idea did cross my mind. After thinking about it for awhile though, I decided it wouldn't be a good idea, since the air carrying the smoke particles had already been through the fire, and would have a lower oxygen content than normal air. After a few cycles, it seems like there wouldn't be much oxygen left in the system. Perhaps Weygers' design had a way of avoiding this, or maybe it just wouldn't be a problem at all.

Thanks!

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I'm sorry you have never heard of Weygers; from his wikipedia entry: "Alexander George (Alex) Weygers, (October 12, 1901–July 23, 1989), was a polymath Dutch-American artist who is best known as a sculptor, painter, print maker, blacksmith, carpenter, philosopher, Aerospace engineer and author."

I learned to smith back around 1981 from his book "The Modern Blacksmith" and was overjoyed when they republished all three of his blacksmithing books as "the Complete Modern Blacksmith"

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4 hours ago, Chelonian said:

Would there be some way to add a filter to it so that it captures the smoke particulates?

Not a filter but wood stoves have a catalytic converter in the stack/chimney that burns off emissions like creosote, smoke, CO2 from wood fires, pretty expensive though.

 

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Yeah, that'll work Chelonian, I recall seeing something similar in a book from a while back. Maybe an article or early internet discussion. I doubt the last, there were drawings. It's similar to keeping a hole punched in the top of the coal pile to let a little flame escape which ignites the smoke. 

I recall someone mounting a small propane burner near the stack to burn the smoke as well but his reviews weren't so good. You don't really want a second burn going on IN the stack. I'd play with a small flame/fire just inside the side draft hood opening to keep the smoke burning.

Just remember coal smoke is flammable and can explode as in blowers popping hard enough to blow cinders out of forges or split seams on bellows. Building a fire in a ring maybe ideal but I think it's overkill.

If you're sensitive to coal smoke you can buy respirator filters for everything in it.

Frosty The Lucky.

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8 hours ago, ThomasPowers said:

It should be described in "The Complete Modern Blacksmith"

Page 100 in my copy. Lots of info in the book. I would recommend reading it.

Laynne

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Perhaps you could consider alternative solid fuels. Charcoal (too expensive for me) and dry whole feed corn would not produce as toxic a smoke.

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Thomas, now that you mention his full name, I do remember reading about his "discopter" (VTOL aircraft) a while ago. I didn't know he was a blacksmith though.

Frosty, thank you for that information. I think I'll just rig up a really simple setup as a proof of concept. If it ends up working really well, I'll make a more permanent version. If not, I will have wasted very little time.

David Thomas, I did used to use charcoal, but I stopped because as you mentioned, it's a bit pricey. I am interested in trying the corn though, I'll look into it. Thanks!

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