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Posted By buildingmaint,
Apr 16, 2007 at 9:26 PM
Oh so those are your tax documents I've been shredding I mean pelletizing....
I don't think that plant is up and running yet .
It's a bagging facility..... and yes it was up and running.
No, its up and running. Been there. Sold tons and tons of the stuff so far. Good pellet, good folks too, running that Palmer plant. They busted their behinds to get that place up and running, not to mention working the kinks out. They need someone like GVA there, tho.....and Mrs GVA to lend helpful, insightful advice. :cheese:
I bet all those ex-hippies would be able to do that, since they all have lots of practice 'hand rolling' things that burn
seriously, I have always wondered about mixing corn starch with sawdust to make your own pellets. Probably wouldn't work.
So, not owning either a Pellet stove nor a Coal stove with like the Harman Magnum Stoker, What is the real difference between a stoker coal stove and a Pellet stove becides the feed rate and blower volume?
Why couldn't a coal stoker burn pellets or vise versa?
Pellet stove's feed rates, auger, burn pot are not designed for coal. Pellet stoves typically have a forced draft exhaust fan that is not designed for coal.
A bottom fed (Harman) stoker for pellets is probably quite similar to a coal stoker.
However, there is probably longer residence time in the burn pot for the coal, etc. -
I don't know of any top loading coal stockers, although it is probably possible.
Harryback has had them all apart - perhaps he can confirm the differences.
Maybe a bit larger scale then you were thinking..
Im not familiar obviously with ALL stoker stoves, but the Harman magnum stoker uses a pusher block assembly rather than an auger to feed the fuel in. The size of the burn area is MUCH greater as well in the stoker rather than the pellet unit. Steel and cast iron seems heavier as well. The magnum stoker controls are basically timing based, whereas the pellet units are generally temperature-based. The stoker units require a chimney, or, (ugh), a powerventer, except for the DVC500 which uses proprietary pipe for venting, but is vented thru a sidewall (it still uses a pusher block though). Another problem with an auger feed and coal is that due to the higher temperatures, the flights of the auger burn off, and fairly quickly.....there was a Harman that used an auger to feed coal once upon a time, no longer made, called the Magnum44....due to several issues, it isnt made anymore....this was about as close to being a pellet stove as a coal stove could be. One of the major problems with coal was the water in the coal...most coal is pretty wet, at least when its bagged. Water + coal + burning = sulphuric acid, which isnt real good with steel. Harman sticks with a pusher block now in all of their stoker units, tried and true, seems to work best. Alaska stoves uses a oscillating piece of steel and an inclined plane to feed coal....a different method of delivery, and pretty problem-free, as long as you remember to remove the ashes.
Sounds to me like a coal stoker could... in theory be "adjusted" so that it could burn pellets. Drop in a smaller burn pot, load with pellets, flip the fuel switch to "Pellet" and off she goes. (HEY HARMAN...I get credit on the Patent!!)
Perhaps in theory, but pellets are virtually always a good bit more expensive than coal, so there might not be much demand.
I remember the EFM coal stokers, and I think they used an auger - but then again they may have used that to get the fuel close to the pot, and then something else to get it right into the pot.
Hey - they are still in business!
looking at the manual, it appears to be an auger which terminates shy of the firebox - it would seem that this type of design would eliminate the excess heat on the auger.
This stoker is tried and true - they've been in the field for 50 years -- I have a good friend who has one in his house with the oil backup.
Never having burned either, I've wondered about this as well, and I suspect the problem is probably to do with the volume of fuel involved. My understanding is that a pellet stove has a very small amount of fuel burning at any given time - maybe about a quart pot's worth. Coal on the other hand needs to have a considerably larger volume of fire to maintain enough combustion - you have to get the coal hot to burn it, which takes a pretty good sized fire, maybe a cubic foot worth... Thus a coal stove wouldn't burn pellets because you'd get too much heat from that many pellets going up at once and overfire. A pellet stove can't burn coal even if it was pellet-sized because the fire wouldn't be big enough to be self sustaining.
This is pure guess work on my part though, so I'd hope that Corie or someone else with expertise in both technologies could say if I'm right or if there's some other reason...
I'd add to your analysis, burn rate. I think it takes coal much longer to combust than a wood pellet. The feed rate to replenish a fire would be radically different for the two fuels. Doesn't seem to me to be a realistic combination/multi-fuel option.
Wouldn't seem to me like feed rates would be that big a deal - after all we have adjustments for such things, though it might take a "coal setting" and a "pellet setting" to set appropriate adjustment ranges. However I think some of the other issues raised are probably better reasons why it wouldn't work...
augers work fine in many many coal applications, the key is to not have the air enter untill a point much higher in the "burn pot" thus preventing excess heat on the auger. this setup usually requires more space than push-block design, thus it is more common in coal furnaces, in a stove where space and compact design is a concern push-blocks are favored. the reason augers have problems in this setup has to do with two issues combining; the close proximity of the fire bed to the auger heating and thus softening the steel, and the abrasive grinding that takes place w/ anthricite vs. softer coals, this causes wear on the auger in excess of other applications where the perform well for decades of use.