Torrefaction

[woodland]

I think you'd have to sell a lot of "posh firewood" to recoup the 20 GRAND outlay, plus pay for the fuel (or account for the fuel) to keep 1 ton of wood at 200-300 C all day, plus account for the labor to fill/empty the thing...

 

If one of the selling points is to provide a "cleaner" fuel, are the "volatiles" kept out of the environment during the process, or just burnt off on site?

 

One of the selling points is to produce a product containing more energy per weight unit, this does not seem to count the fuel used in producing it.

 

Seems like it's just "part burning" the firewood for the customer, and charging them for the privilege!

 

But I may have the wrong end of the torrefracted stick:confused1:

 

They reckon that it will take 80Kg of dried woodchip to power the gasification generator to get the reactor up to 200 degrees at which point it becomes exothermic so ya it then uses the volatiles to continue the process. I think the unit would be fine if you intend living off grid but I reckon you you would have to head for the industrial scale to make it finically viable.

 

I understand that there is a fair amount of sales pitch but producing a hotter burning fuel has to be a good thing, granted it may not suit all stoves etc but burning diesel transporting water around the country dosent make a great deal of sense, just my thoughts, maybe stove manufactures need to start redesigning their stoves to accommodate kiln dried and torrified wood

[renewablejohn]

woodland

 

I think you misunderstood its not burning diesel transporting water. Its just a diesel engine can efficiently burn a lot of other fuels instead of diesel. If you have torrefied wood (charcoal) and want to run a combined heat and power generator you basically have two options in running your diesel engine. Either run it as a gasification plant in which case you need either 20% diesel or spark ignition or run it on slurry which is 50% pulverised torrefied wood and 50% water.

[billt]

I think that he meant the diesel burnt in transporting the water in normal logs.

[woodland]

I think that he meant the diesel burnt in transporting the water in normal logs.

 

Indeed I did:thumbup1:

[woodyguy]

If I put logs at 20% MC off my log pile on top of my stove for 24 hours then they have a MC of 6%. They burn very quickly and very hot. If I leave them there for a week they will get down to 2-3% (all measurements by weight as moisture meters are hopeless).

I personally wouldn't pay inflated prices for bone dry wood (which would pick up moisture in storage anyway) and I doubt whether many other would. Especially as it looks hideous which really matters to the types who pay top whack for wood.

[face cord]

which would pick up moisture in storage anyway

 

Torrified wood is suppose to be hydrophobic so it won't reabsorb any moisture. I also dry wood on top of the rayburn or in the oven but it has an annoying tendency to catch fire if left on to long

 

Need to work out how to do it but without any oxygen getting to the wood, so it doesn't start to smolder

 

 

 

Noticed that they are also selling a rocket & heat exchanger stoves for coppice wood

 

http://www.blackmountainwoodfuels.co.uk/pdfs/THE%20STICK%20STOVE%20-%20BROCHURE.pdf

[woodyguy]

Do we have any evidence that "Torrified wood is suppose to be hydrophobic so it won't reabsorb any moisture"

If charcoal absorbs water then why should this be any different.

I'm lucky that my stove top is only at about 100c so doesn't char.

[billt]

Torrefaction - Wikipedia, the free encyclopedia says

 

"Torrefaction is a thermochemical treatment of biomass at 200 to 320 °C. It is carried out under atmospheric pressure and in the absence of oxygen, i.e. with no air. During the torrefaction process, the water contained in the biomass as well as superfluous volatiles are removed, and the biopolymers (cellulose, hemicellulose and lignin) partly decompose giving off various types of volatiles. The final product is the remaining solid, dry, blackened material[2] which is referred to as “torrefied biomass” or “bio-coal”.

 

During the process, the biomass loses typically 20% of its mass (dry bone basis), while only 10% of the energy content in the biomass is lost. This energy (the volatiles) can be used as a heating fuel for the torrefaction process. After the biomass is torrefied it can be densified, usually into briquettes or pellets using conventional densification equipment, to further increase the density of the material and to improve its hydrophobic properties. This means that the final product repels water and thus can be stored in moist air or rain as opposed to the original biomass it is made of."

 

Which sounds quite credible. Water in wood is stored in the cells, which have slightly permeable walls. If the structure is changed so that the cell walls become impermeable after the water is driven off then water won't be able to get into the fine structure of the wood so it stays dry internally.

[renewablejohn]

Do we have any evidence that "Torrified wood is suppose to be hydrophobic so it won't reabsorb any moisture"

If charcoal absorbs water then why should this be any different.

I'm lucky that my stove top is only at about 100c so doesn't char.

 

Simple test.

 

Wood pellets in a beaker of water the pellets expand and break up.

 

Do the same with torrefied wood pellets and you still have the pellets a week later.

[face cord]

Pdf on there website has more detailed info about all there stuff:

 

http://www.blackmountainwoodfuels.co.uk/pdfs/POWER%20TO%20THE%20PEOPLE.pdf