burning wood chips in stove

[smirnov3]

Has anybody tried burning green wood chips in a stove?

I remember reading last year about some guy in Vt who was making a special stove to do so, but I was wondering if there was a way to do it in a regular stove. The trick was that you had to burn the stuff slow.

 

[webbie]

One of our forum members makes a stove that can do this - with a hopper attachment.
http://www.sedoreusa.com


But, the concept of burning GREEN chips sound suspect, because as we know it would take a large percentage of the energy to burn off the moisture. The Sedore would probably do it to the degree, because the stuff in the hopper would dry out while it was waiting to be burned. But there is no free lunch, so the efficiency will be reduced by the amount of BTU needed to dry the wood.

Notice in the tour of the pellet plant, they burned a large percentage of the sawdust just to dry the rest of it!

 

[smirnov3]

One of our forum members makes a stove that can do this - with a hopper attachment.
http://www.sedoreusa.com


But, the concept of burning GREEN chips sound suspect, because as we know it would take a large percentage of the energy to burn off the moisture

According to the guy's website, the loss is only about 15%.

Which, given how cheap wood chhips are, is an acceptable cost.

the below is from http://www.sredmond.com/vthr_page2.htm

The heat contained by this steam is lost. This fact has sometimes been mentioned as a criticism of green chip combustion. A common mistake is to think that 50% moisture content by weight means 50% less heat. We recently lost a Vermont EPSCoR research grant competition because a single reviewer made a similar intuitive mistake without calculating the amount of stack loss.

While it's true heat is given up to steam, it is an acceptably small loss compared to the heat produced.

To understand this we need a little math. Here it is:

Sensible heat is the heat needed to bring the moisture in the chips up to 212 degrees, plus any additional heat after stream is formed.

Latent heat is the heat needed to create steam from 212 degree F. moisture.

For 1 pound of 50% moisture chips, water raised from 60 to 350 degrees:

Sensible heat = (350 - 60 degrees) x 0.5 lbs = 290 x .5 = 145 Btu
Latent heat = (970 Btu/lb) x 0.5 lbs. = 485 Btu
Total lost heat = (145 Btu + 485 Btu) = 630 Btu
Fuel Heat value = .5 lbs. x 8600 Btu/lb. = 4300 Btu
Heat loss = (630 Btu/ 4300 Btu * 100%) = 14.6%

 

[webbie]

That sounds right - about 1/6 of the wood - I think that was the amount that the pellet plant used....or maybe 20%, because they are bring the moisture content down lower than firewood.