soot problem

soot problem

PostBy: specialtee On: Mon Jan 12, 2009 9:04 am

(originally posted in the stove section and recommended that I post here to get advice from the experts) I've been burning wood in a newly installed US Stove Clayton 1800. Until yesterday. That furnace can really go through some wood! Any way, I had some bituminous available and wow...talk about a hot fire. I was real happy. I loaded about 20 lbs on top of some wood embers and the coal fired right up, once the coal stabilized a little I added about 20 lbs more. I continued this way trying to fill the box up to the top of the bricks just like I had read on this forum but every time I would start to put in the larger load to fill, the new coal would really take off and I would get so much fire and smoke I had to shut the door til it calmed down. About 6 hours into this process everything went south and I noticed smoke coming out of the pipe joints, check the chimney cap and the bird wire in the cap had sooted up so up on the roof I go at 2am...boy its cold up there!
What did I do wrong to cause enough soot to close off my cap after only about six hours of coal? I ripped the bird wire out of the cap for starters, still got a good fire going, bottom draft knob is closed and the forced air draft is on. On problem I have with the forced air draft is that the slide plate that restricts the air tends to vibrate all the way open very easily, so that is were it tends to wind up. Were should this thing be anyway?
specialtee
 
Stove/Furnace Make: US Stove
Stove/Furnace Model: Clayton 1800

Re: soot problem

PostBy: twainer On: Mon Jan 12, 2009 3:21 pm

Well, I was going to post anyway on my progress with a new coal boiler. Originally I installed my chimney through the block wall and then up, but the two 90s this required caused all manner of soot to jam up in the 6 inch pipe. Bit coal seems to create a lot of soot on the sides of the chimney pipe, enough so that my 3 foot level section that passed through the outside wall would plug solid with soot within 2 to 3 days.

I realigned my chimney pipe during a hot spell just after Christmas so it now has no 90s and I can just open a T pipe to dump out excess soot. The fire burns totally different with the new chimney now. I also try to burn a chunk of wood every few days--I heard it helps keep the soot down but can't confirm that. Bit coal just creates a lot of soot it seems. This isn't a problem with a decent chimney, but as you mentioned, you had the screens up top that got clogged up pretty fast. Bit coal just has more particulate matter in the exhaust than you are used to.
twainer
 
Hand Fed Coal Boiler: Bermuda (Chapee) solid fuel boiler
Coal Size/Type: bituminous lump
Other Heating: Natural gas boilers

Re: soot problem

PostBy: steinkebunch On: Mon Jan 12, 2009 7:21 pm

I burn Wyoming Bit. coal and have experienced soot problems with my handfed stove. From what I can tell, you have to burn the coal pretty hard to get enough heat to actually burn the volatiles, instead of letting them go up the chimney and form soot. The problem then is usually that you get too much heat when you burn the average sized firebox hot enough to burn the volatiles.

I tried using firebrick in place of my baffle plate to direct heat back down to the coals, to burn the volatiles, but I had limited success.

Berlin, one of the bit. experts, claims that if you can provide preheated seconday air over the fire, you can burn the volatiles also. I never was successful at doing this, mostly because I refused to cut a hole in the front of my stove to accomdate something similar to Berlin's secondary air design (see that thread at coal/wood stove plans). If you were handy, I think that his secondary air design would be worth a try.

The conclusion I came to is that it's best to have a firebox that has a small area (footprint), and also a very deep firebox. That way you can burn it hard, and not get too much heat out of it.

But that creates problems also, as when the volatiles have burned off after a few hours, you may be left with not quite enough heat.

That all led me to find an underfeed stoker, which burns a small amount of coal very fast. It seems to work very well, though even then I have some soot. Still working on that.

Good luck. If you can reduce your firebox somehow, by laying firebrick on some of the grates, and still maintain a system to shake the ashes out, you might want to try that. Preheated secondary is also required, but tricky to fabricate.

Steinke in WY
steinkebunch
 
Stove/Furnace Make: Homemade Bituminous Hand-Fed
Stove/Furnace Model: Prill underfed stoker Model M8


Re: soot problem

PostBy: BigBarney On: Mon Jan 12, 2009 8:14 pm

Specialtee:

I would try not to fill the firebox too full with fresh coal.

With the long narrow firebox you have you should shake down and then

push all the hot coals to the rear of the firebox and load your new coal

in the front only overlapping the new coal a small amount on top of the

burning coke in the back so it will start to burn and the hot volatiles gases

are directed over the hot coals and are burned.This method of firing is

used with bituminous high volatile coal to force all the free carbon to

burn before leaving the firebox.Much less soot goes to the chimney

and is burned for greater heat.

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BigBarney
BigBarney
 

Re: soot problem

PostBy: Berlin On: Tue Jan 13, 2009 1:02 am

bigbarney is absolutely right, with the long, narrow firebox you have, it's best to fire it as he said. If you simply keep spreading a thin layer of fresh coal on the hot coals already in the firebox, you will create a lot of soot with that particular appliance. I also always reccomend removing any screen/mesh/cap on a chimney used with bituminous coal, it also tends to make life easier if there is at least an 8" flue pipe between the chimney and the appliance.

to burn bituminous with as little soot as possible in a hand-fired appliance (there's always some soot) it needs to be fired (or designed) one of two ways; either bank the coals as big barney has said allowing the very hot fuelbed to slowly ignite the new coal; or by good design and air-tightness, keep the fuelbed cool enough that the volitiles are not released too quickly from new coal spread evenly over the hot coals; this will require a preheated secondary air setup to ignite the volitiles and a deep, square firebox, not what you have, unfortunately.
Berlin
 
Hot Air Coal Stoker Furnace: Will-Burt Combustioneer 77B
Coal Size/Type: Ohio BITUMINOUS pea stoker coal

Re: soot problem

PostBy: danzig On: Tue Jan 13, 2009 12:56 pm

I have been burning a good amount of bit this week. I have been burning high vol(redstone), and med. vol (freeport) coal I load the entire firebox chamber with coal 3" deep on the shaker grates. I stack kindeling and tinder on top. I light the kindeling let the fire roar. It lights the coal I wait until the volitals burn off. Add more coal let it burn. Add split logs on top to help the bridging. When logs are burned down poke the remaining coal let it burn and then refresh the fire, start over again. Try this method it has been working well for me to help keep the soot and fly ash down in the chimney pipe. also note I keep the secondary air hole (control! for you coal equipment termonology heads!!) open during the hole burn cycle. Also I put a magnet on my baro (to deactivate) to keep the gases hot going out the chimney.
danzig
 
Stove/Furnace Make: logwood ycob36 boiler
Stove/Furnace Model: simplex multi therm

Re: soot problem

PostBy: specialtee On: Thu Jan 15, 2009 10:19 am

Danzig,
What size coal are you burning? Part of my problem has been I using up the bottom of my coal pile and its about 80% fines. It has been areal challenge to burn for me. The wood on top to get it going sounds like a good idea except I have used up my wood supply and that is why I switched to coal. :shock: :wacko:
Thanks for the info
Greg in Signal Mountain
specialtee
 
Stove/Furnace Make: US Stove
Stove/Furnace Model: Clayton 1800

Re: soot problem

PostBy: twainer On: Thu Jan 15, 2009 12:04 pm

Specialtee,

Even though I straightened my chimney pipe, I still need to get out and clean it every couple weeks it seems. The soot just totally blocks off the pipe near the top. This is a straight 14 foot long stainless 6 inch pipe! Cleaning isn't a problem as the roof is very low, but its still a hassle.
I don't think there is anything much to be changed with the burning technique on my boiler. Like you said, I'm burning coal and not stocking wood. The coal just creates lots of soot for me here too.
twainer
 
Hand Fed Coal Boiler: Bermuda (Chapee) solid fuel boiler
Coal Size/Type: bituminous lump
Other Heating: Natural gas boilers

Re: soot problem

PostBy: BDHodosn On: Mon Feb 09, 2009 9:15 pm

BigBarney wrote:Specialtee:

I would try not to fill the firebox too full with fresh coal.

With the long narrow firebox you have you should shake down and then

push all the hot coals to the rear of the firebox and load your new coal

in the front only overlapping the new coal a small amount on top of the

burning coke in the back so it will start to burn and the hot volatiles gases

are directed over the hot coals and are burned.This method of firing is

used with bituminous high volatile coal to force all the free carbon to

burn before leaving the firebox.Much less soot goes to the chimney

and is burned for greater heat


Pretty much how my grandfather and uncle taught me for bit. in the boilers they had. Bank it toward the back, load the front. They had huge clay lined chimneys as I recall. It's also why I have an anthracite stove...
BDHodosn
 
Stove/Furnace Make: Hitzer
Stove/Furnace Model: Model 82UL

Re: soot problem

PostBy: Berlin On: Mon Feb 09, 2009 9:37 pm

burning most bituminous coals really is not that bad. even with equiptment not well designed for it, many times bit coal can still be fired relatively easily. the problem is not the soot, bit coal can be fired properly in a proper appliance to produce less soot, but it still produces soot; so regardless of how much soot you make the chimney should be able to handle it w/ out much of a problem. If the chimney is too small or poorly designed then you're going to have issues- no matter what. It may be cleaning every week, poor draft and performance or cleaning every month, but none of this would be a problem if it wasn't for an improper chimney- specifically one that is too small. 6" is TOO SMALL for bit coal burning and is barely adequate for small wood furnaces regardless of what the mfg's say; you can use a 6" chimney, but it won't be fun.
Berlin
 
Hot Air Coal Stoker Furnace: Will-Burt Combustioneer 77B
Coal Size/Type: Ohio BITUMINOUS pea stoker coal

Re: soot problem

PostBy: BigBarney On: Mon Feb 09, 2009 10:37 pm

Here is how my boiler burns with bituminous coal and natural draft.

It has a blue flame but the red coals overpower the blue color of the flame.

This is looking into the secondary draft at the grate level,in this base burner

the fire burns at the bottom of the fire pot and the unburned coal is on top.

The exhaust flue is at the grate level where the hottest fire is and the unburned

gases pass through this hot coke bed and are consumed for more heat.


Which filter on the camera help get more of the blue flame color?



BigBarney
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Re: soot problem

PostBy: danzig On: Tue Feb 10, 2009 12:16 pm

I have a marathon logwood coal boiler it has a 7" chimney. to date I have no problems with soot and draft.
The size of coal I am using is run of mine (large, small, fines, etc) I somtime load my coal banked in the back. I put wood on top to light the coal and let it burn from the top down
danzig
 
Stove/Furnace Make: logwood ycob36 boiler
Stove/Furnace Model: simplex multi therm