[Stoves] Stoves Digest, Vol 38, Issue 8

[neiltm at uwclub.net]

On 8 Oct 2013 at 12:00, stoves-request at lists.bioenergylists.org wrote:

> Does anyone have any ideas on simple ways to dry woodchips.

On what sort of scale?

On a domestic cooking scale, my son is able to supply me with sacks full 
of green woodchip. I employ two stages. I spread the green chip out on a 
plastic sheet outdoors in the sunshine, occasionally raking and turning 
it.  After sometimes a day,  sometimes two it has lost enough moisture to 
replace in a hessian sack without thermophillic bacteria composting it.  
Then I fill a foil tray with the chip and keep it on top of our domestic 
boiler to fully dry out, so fully drying small quantities just before the 
point of use in the woodgas stoves.  Lots of possibilities to do that.

Split sticks for the rocket is even easier, I simply cross stack them in 
a garden shed and let them dry out in the heat of the sun warming the 
shed interior.  Only takes a few days from green if sunny.  If I needed 
to increase the rate of production of dried chip I would cover chicken 
wire shelves with onion sack mesh, and have a stack of shelves in the 
shed with the chip spread out.  I use these sacks as a riddle to remove 
dust and too small particles.  Any enclosed but porous/draughty structure 
with a corrugated tin or tarred felt roof is going to be usefully 
employable and produce in a few days with sunshine.  I once came across a 
collapsed pitched, rusty corrugated tin roof barn.  The uprights having 
collapsed, the roof was intact on the ground.  On the sunny day the heat 
under it was incredible (that's in degrees fahrenheit ;-), even with open 
ends. 

On a larger scale, my son seasons mixed estate wood in open stacks and 
then chips it dry for the new woodchip boiler at the visitor centre, 
restaurant and offices. Disadvantages are that this is harder work and 
wear for the chippers and a lot more dust is produced. Done commercially, 
a proportion of the woodchip itself is commonly used to heat dry green 
woodchip in the UK.  Recently, against his advice they got him to chip 
some wood he told them was not dry enough, and they ended up with a 
chimney fire and an alarmingly hot pile of chip in the open sided store 
shed!  Their options really are to continue to season wood in open piles, 
then chip it, or to sell the wood to commercial chippers and buy it back 
from them as dried chip.  No one has suggested solar driers for their 
scale of operation, and we're not aware of any.  

Neil in the sub sub tropical UK.