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General Forestry => Firewood and Wood Heating => Topic started by: Crhall on February 21, 2018, 02:38:52 PM

Title: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 21, 2018, 02:38:52 PM
I have access to a bunch of free scrap lumber. It not exactly pallets, but pretty close to what  i would think pallets burn like. The two main sizes are boards that are 1.25" thick 6"-12" wide and 12"-18" long. The other pieces are sticks that are 1.25sq x 4ft long. It comes in steel crates that are 4ftx5ft. There's no cutting involved to add to extra labor other than setting it by the boiler and putting pieces in. Its all hard wood, mostly oak, ash and poplar. And it is dry.

So i did a test and filled my OWB about 1/4 full of this stuff with no cord wood. Once it called for heat, the fan kicked on and it started to burn.. It smoked very bad! I've had regular firewood smoke pretty bad before, but not all the time and not quite this bad! Also it sound like a fireball inside the stove. You crack the door and can hear the pressure of it trying to push out the door. Its burning hot! From the little bit of research i have done, it sounds like with the smaller dryer wood, its all trying to ignite at once, vs and large round just sitting in there burning from the outside in. As this stuff is all trying to burn at once, it can't get enough air in or push air out. therefore shooting out all the dark (unburnt) smoke.

I haven't been around it during the later heat cycles yet to see how smokey it is, but the first 2 has been very bad. If this stuff wasn't free and so easy to just set a bin next to stove, i wouldn't worry about it. But even if i mix it with cord wood it would be helpful on consumption. Is there anything i can do to help ease up the smoke? Or is that just what this little stuff does? I know there are companies that even make boilers made to burn full scrap wooden pallets, it would basically be the same if not worse because of all the air gaps in between the skids. Do those pallets burners smoke bad when first filled?

Does anyone else have other reasons why this is burning this way? I really thought clean dry hardwood would burn pretty nice. Any suggestions on what i can do to clean up the burn (other than buy a gasser)
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 21, 2018, 06:04:03 PM
You are pretty much correct, it has way too much surface area for the amount of air that can get to it and it runs extremely rich. Depending on what OWB model you have you might be able to stack the wood so air can slip by the wood up on top and burn off the smoke. Only load maybe half full.
A downdraft unit would do better as the fuel-air  mix would be better regulated, but it might still smoke.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: thecfarm on February 21, 2018, 06:12:39 PM
I wonder if the wood is packed in the firebox,due to no air spaces,if that is the problem. Could you put in a couple pieces cross ways,to give it some air space? Put some cross ways every few layers.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: jason.weir on February 21, 2018, 07:25:00 PM
try unplugging your draft fan if you can - my CB doesnt have a fan and would burn what your talking about without additional smoke...
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 21, 2018, 09:30:24 PM
Sorry I forgot to add that, Its a Heat Master MF10,000E. I wonder if I could put a few normal chunks in first then somehow stack it on top where it can get a flame up through it. I just wish I could figure out a way but I just can't see it. I'm having a hard time grasping the fact the small dry wood has way more unburnt fuel/gasses/smoke vs throwing a large green round in. What about slab wood, do people have the same problem that burn that? They would have to, right? I normally burn nice split seasoned hard wood, Sometimes I will have some large rounds for the really cold nights, but i'm not one to throw green chunks in because I know I get more btu's from dry wood. I have almost no smoke once my normal spit firewood lights.

I wonder what this stuff would do in a gasifier if it would be able to burn all the gasses.. Doesn't  really help me as mine is not a gasser.  I could maybe just try to burn the boards, the 8"x18" stuff mixed in with my normal firewood. I would think those would burn almost like slab wood. Its really hard to overlook all this free unlimited wood, but I don't feel I can burn it like its burning now. Its just not right. I played around with my draft control tonight, didn't change much, I really didn't notice any worse or better. I don't understand if there is only so much air intake, and only so much that can be exhausted, then why is it all trying to light at once? why wouldn't it just start at the bottom of the stack and work its way up like it does on firewood?

Now what if like Jason says, Is the draft fan is pushing way too much oxygen than what can be exhausted? On the other hand I would think if it didn't have the fan blowing, would it just sit smoldering and smoking? Again, this is very tough understanding why small clean dry hard wood is not burning clean and has so much smoke/unburnt fuel
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: thecfarm on February 22, 2018, 06:46:36 AM
I've burn slab wood. No problem at all. BUT you have to to remember slab wood has a half round to it,allowing air into those spaces.
Could you cut some up into short pieces and just throw it in in all directions? Just to try it once and see what happens. As you said you might have to mix it with your regular firewood. Too bad you could not make it work,it's free wood.
 
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: TKehl on February 22, 2018, 09:16:35 AM
Have you tried putting less in more often?

I'd be all for mixing it in with regular firewood.  

Even so, I figure the alternative to you burning it would be to dump it in a landfill.  Better to get some use even if it smokes unless you have local laws against it.

The only downside for pallets is I've seen some of the chemicals that have been spilled on the ones we use and wouldn't want to burn them.  If they look pretty clean or low usage/you know their history, I wouldn't hesitate.  I probably would burn some, but it's easier for me to cut firewood than haul pallets and I don't want to deal with nails.   ;)
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: ButchC on February 22, 2018, 09:23:02 AM
Your post reads like you only tried it once? If so one thing that happens especially if you have been burning big chunks of wet wood is the scraps burn hot enough to burn a bunch of the creosote out. Once cleaned out the scrap wood should burn with a cleaner stack than cordwood,, at least mine does.
I save the slabs from my sawmill and  other scrap to burn in the spring and fall when there isnt much heat demand and have had similar things happen many times but once burned out it should burn clean.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 22, 2018, 11:00:31 AM
I've burned an MF model unit in the past and with bottom air blowing heat from the coal bed up on very dry small wood it does tend to light up everything at once. Try piling the scraps/small pieces toward the back and leave an air hole on the front grate, even perhaps letting some ash pile up on the rear grate to force more air up the front near the firebox door. It needs plenty of room to burn off the huge volume of gasses produced so you can't pile it full up near the exhaust at the front.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 22, 2018, 11:54:19 AM
I've been burning it since Monday. And yes i thought that to first time i burned it, it just burning out all the creosote out and crap out. but it was still doing it last night, i've only been throwing wood in once a day (eve) with the 40* temps right now. But i've noticed lots of black in it from longer idle times, thats almost with any wood right now and warm temps.

Yoder may have something here, these pieces are 4ft long, my inside is only 4ft, so when i stack it in, the front part of grates are covered with wood, thats were i could be hurting myself, it needs to produce a pretty hot air forced flame right there in the front in order to burn off those gasses above. With the blower under the grates, that is where most the air normally comes up, if i'm blocking it with wood, then it has no where to go but to try make its way up threw the tight stacked sticks. Would have same issue with 4ft long slab wood stacked in there i bet also. So i could try 2 things. 1 try 3ft pieces to leave a ft of grate open, or put a hunk of wood in about a foot in, then stack 4ft pieces in leaving larger air gap between grate and sticks?? Could ones of these maybe work, worth trying i guess

Yes, I'd love to keep it out of a landfill and use it for heating. Its free, no cutting, nails or added work involved, just straight from lumber mill. Just need a way to make it work and be somewhat efficient. I plan on being home this weekend to try things, but temps still in 40's is not going to work the stove very hard.

Yoder i just noticed something, is that your vid on youtube where i posted same question where a lumber yard is burning scrap lumber? I didn't even look to see where you were both from VA
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 22, 2018, 06:52:03 PM
Yup, that's me several years ago. It just clicked today with me that it's the same. Internet's a small place. :)
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 22, 2018, 07:02:41 PM
Yeah, I'd cut one load down to three feet long and throw them all the way to the back. Be interested to see if it helps. On that video if they were shoveling it level full and choking it it would have rolled smoke like you wouldn't believe.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 22, 2018, 08:29:10 PM
Haha yes it is, I ran across that vid and thought if they can burn that, somehow I have to be able to burn this stuff!! So little test I did tonight was just loaded it with the scrap cut off boards, no sticks, they are 18"-24" long 6"-10" wide. same wood same thickness and same moisture as sticks.. Left the front part of grates exposed, and waited for it to call for heat.. Right away I could tell the difference. Way way less. It smoked like normal firewood that was just loaded. Once it started to light good I think the smoke was clearing up some!! I think this weekend I may try taking the 4ft sticks and loading them on the sides, kind of cross the back end in a X so the front grate stays exposed. I think it will burn good then!! I'm not expecting this to be a complete replacement by any means. I know in the deep winter when 0 below temps, I be still loading it with large rounds and dry splits. But for temps above 25-30, I think this will really save cord wood usage!! Thanks again everyone, i'll let you know what this weekend brings. Yoder thank you, Also is that place still using that boiler to burn the waste? How is it working now?
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 22, 2018, 08:57:01 PM
They did that for several years and then built a second shop and upped the total square footage to 24,000 square feet. At that point handloading became too much of a chore and was really more heat load than it could reasonably handle, so they put in a grinder and got an auger fed B500 chip burner from Heatmaster. Now they fill the bin and forget it for several days.
The MF10e was sold and is heating two houses and still chugging along.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 25, 2018, 10:16:09 PM
I played with it some this weekend. Yoder, I still don't know how you got it to burn clean. Its definitely more smoky than normal cord wood.. I burnt some cord wood today, its cleaner. I think tomorrow I may try mix it see what happens. Any other suggestions to try? Do you remember where you set the air damper.. Here's what this stuff looks like., no reason I shouldn't be able to burn it
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 25, 2018, 10:22:03 PM
Well I can't figure out how to load the picture
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: thecfarm on February 26, 2018, 06:03:39 AM
http://forestryforum.com/board/index.php?topic=100194.0 (http://forestryforum.com/board/index.php?topic=100194.0)

This link should do it.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 26, 2018, 07:19:54 AM
Thanks, Here pic of this stuff, this bin is roughly 4ftx5ft x4ft tall sides to give you rough idea on size of material


(https://forestryforum.com/gallery/albums/userpics/39206/thumbnail5.jpg?easyrotate_cache=1519647500)
 
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Gary_C on February 26, 2018, 09:06:10 AM
What does the smoke look like? Light colored or dark?

If it's light colored and looks like clouds, it's more steam than smoke and just means you have wet or green wood. Check the moisture content of the scrap you are burning.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 26, 2018, 09:40:01 AM
Its more dark. Like unburnt fuel. This is one of worse pics after i just loaded it, it gets little better than this after few minutes. But still not near as clean as reg cord wood. Its reading around 18-20% moisture... I would think saw dust would be 10 times worse, like just smoldering for air, but i seen the vid, Yoder has it burning good somehow 


(https://forestryforum.com/gallery/albums/userpics/39206/20180226_093203.jpg?easyrotate_cache=1519655581)
 
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 26, 2018, 01:33:17 PM
The sawdust actually helps quite a bit as it doesn't allow as much of the little blocks to be exposed. Less available surface area.
That small dry stuff will gas very quickly and burn very rich and I'm not sure how you can stop it.
Have you tried leaving the front grate completely open with no wood over it at all? It's going to take a lot of air to burn off that rich mixture.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 26, 2018, 08:09:04 PM
Yeah I did it really helps that's for sure. But still more smoke than regular. I think another factor could be with the warmer temps outside right now, its not burning very long before it reaches temp setting, in just a few min its up to temp so its not running long to get things nice and hot or started to burn. I have it 10* difference now, could try 15 see if it runs longer. I put some in this morning, when I got home it had pretty decent amount left in it and you could tell its been burned on pretty good. When it fired up, it actually was burning very clean. 
I guess it just throws me off so bad because I always thought small split wood burns better and cleaner than large rounds. Seems the opposite on this. I mean I've seen few old timers with new OWB and they have their split into tiny fireplace wood. In theory shouldn't it smoke somewhere in between large rounds and this stuff? Maybe i'm being to picky but that's how i'm wired. Other people just tell me, "free wood? who cares about smoke just throw it in" i'm just different I guess.

I would love to see a Central Boiler pallet burner run, because from what i'm seeing and learning about gases and fuel surface area, it should smoke like a freight train
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Ianab on February 26, 2018, 08:18:14 PM
I don't know much about those boilers, but I would guess that the system is designed for a certain type of wood (size / species / moisture) etc.  This would have to do with the amount of air getting in on both the burn and idle parts of the cycle. So if you want a stove to burn large chunks of wood, it would be designed slightly differently. 

Same as NZ wood stoves are generally set up to burn small dry pine, because the cheapest firewood is usually mill slabs or kiln dried offcuts. I imagine if you put that in your fire it would have all sorts of issues as well. 

But the local fires are designed to basically set the airflow and let it burn. You aren't trying to cycle from full burn to idle all the time, which I can see being a problem when the wood is small, lots of surface area starting to burn, then it tries to dampen the fire down, and you end up with the very rich burn and smoke.  It's almost like you need some intermediate settings on the damper to keep a medium burn running longer, or something like that?
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: thecfarm on February 26, 2018, 08:19:29 PM
WOW! I have burned green softwood and hardwood,cut it down and 15 minutes later it's in the OWB. Rotten wood that must would not even pick up. I have never seen black smoke like that. Yes gray,but not black like that. I wonder what's on those boards?
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 26, 2018, 08:33:58 PM
Nothing should be on the boards, its coming straight from the mill. Heres how it cleaned up when I got home from work
(https://forestryforum.com/gallery/albums/userpics/39206/BOILER1.jpg?easyrotate_cache=1519695123)
 
(https://forestryforum.com/gallery/albums/userpics/39206/BOILER.jpg?easyrotate_cache=1519695123)
 
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 27, 2018, 06:18:20 AM
Yeah, gray smoke is a cool steamy slow burn, black/yellow usually is a rich and hot burn.
Those sticks would probably burn slower and cleaner if they weren't so dry. They ignite too easily.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Peter Drouin on February 27, 2018, 06:23:30 AM
Did you ask someone if the wood is treated with something?
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: coxy on February 27, 2018, 07:30:12 AM
mine will do the same thing if i burn boards or pallet wood don't know why but it will stop after it gets up to temp and wont do it again till you refill it i thought it maybe burning the creosote off the in side of the boiler like the boards are dryer  making more heat or there is more air space letting the flames hit more of the inside of the fire box burning the creosote off  hope you get the idea of what I'm talking about  :)
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Don P on February 27, 2018, 07:51:00 AM
It's what E Yoder is saying. You are heating the wood enough to make a large amount of wood gas and have insufficient oxygen to burn it so that rich unburned gas mixture is spewing from the tailpipe. If you hold a propane torch up there it may well flare. Later in the burn you are basically burning charcoal. Basically you are gasifying without provision for taking advantage of it. That is methane and unburned hydrocarbons spewing from the stack. With dry wood like that a catalytic converter on top of the stack with air intake would provide ignition temps and oxygen to clean it up. You wouldn't get any advantage from the heat produced but it would clean it up. Slide that out of the way when you burn wet wood, which is another problem.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: jason.weir on February 27, 2018, 10:43:07 AM
Quote from: thecfarm on February 26, 2018, 08:19:29 PM
WOW! I have burned green softwood and hardwood,cut it down and 15 minutes later it's in the OWB. Rotten wood that must would not even pick up. I have never seen black smoke like that. Yes gray,but not black like that. I wonder what's on those boards?
My experience as well - never seen black smoke out of my OWB unless I used something to "help" get things going...
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Gary_C on February 27, 2018, 11:56:39 AM
You should also check your exhaust system to make sure there is no buildup or obstruction. 
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: TKehl on February 27, 2018, 01:16:51 PM
I'm with Don P on this.  Hot box, lots of surface area, but a smallish fire.  Perfect for pyrolysis and pyrolysis is great for producing wood gas.  
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on February 27, 2018, 09:55:36 PM
I completely understand whats going on. I knew from day one seeing all the dark smoke is unburnt fuel. Theres no question about that. My whole thing was trying to figure out a way to make it work. Unfortunately I dont's think there is, (that I can find yet).. I was kinda thinking about what Jason said and what would happen if I was to unplug fan? Just let the trap door open for air. That way its not being forced to try and light all the wood at once, What made me think of this was I started to load it after draft fan shut off, I just had the door open and the fire was just slow burn, as I added wood sticks, they were slowly igniting. Nothing was forcing air into it trying to ignite all of it at once. its was burning slow and low smoke. I did try and close the draft door some, but I think the fan just pushing air hard. 
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on February 28, 2018, 05:29:10 AM
Or try throttling the damper below the fan down... But watch for creosote. Slow burning can really do that.
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: Crhall on March 12, 2018, 09:26:12 PM
After playing with it for awhile I got it burning as clean as cord wood (or pretty close to it) Put one or two pieces of cord wood right in middle, then fill the sides and some over it while leaving the front grates wide open. Working nice for free fuel, thanks for all the help guys
Title: Re: Burning pallet lumber (Lots of Smoke)
Post by: E Yoder on March 12, 2018, 09:42:38 PM
Awesome! Free is great.