[Gasification] Self-drying Wood Chips

[AJH]

On Sun, 10 Dec 2006 11:08:48 +0100, Ferruccio Pittaluga wrote:

>Dear all,
>have anybody heard of a self-drying capability of wood chips once stacked up in 3 or 4 layers of say, 20x20 sq.m. area, and about 0.5 m height each, and then sequentially compacted by action of a heavy caterpillar tractor? It seems that a kind of heat releasing "fermentation" takes place, giving off moisture independently of any outside heat supply.

I thought the reason for compacting the chips this way was just so
they didn't respire any of their dry matter away. The thing about
drying chips by allowing them to aerobically compost is that it's not
an efficient means of dying, the products of composting being
essentially CO2 and water if the ventilation is wrong then the water
condenses back out at the top of the heat.

Drying is probably the best use we currently make of solar energy.

In UK the perceived wisdom is that drying of stacks of wood outside
stops in the months OCT-MAY but certain woods (the ring porous ones??)
like sycamore, poplar and willow, continue to dry even with our high
Relative humidity and modest winter temperatures if they are in an
airy shed (poly tunnels are ideal.

Even so once you reach a certain throughput there are big
disadvantages to unassisted air drying, the storage space goes up and
the cost of holding the inventory of harvested wood starts to hurt
cash flow.

A few years ago we made a case for a small firewood producer with
limited space for a fast dryer, he ordered one which we estimated was
5 times too large for his then needs. Since then he has expanded
production to keep the device running flat out at 18 tonnes/day input
and says the business is wholly dependant on this dryer.

AJH