Firewood kiln- anyone made one?

[renewablejohn]

Catweazel

 

Could you please explain a bit more on what system you put in to achieve a figure of £10 per tonne. I looked into various methods prior to going down the solar kiln route. To dry to 10% which I needed for production of wood pellets was going to cost 20% of sales value which is far higher than your figures.

[sandbach-sticks]

Try local timber yards, when I have a request for kiln dried i send logs in IBC crates and it comes back 8-9% 4 days later costs £30 but i just add that to price of logs. Instead of £65 m3 becomes £100. £5 m3 for me . I have ornamental logs dried this way, and Swedish candles. Just another option to consider. I have drawn up plans for our own kiln, basically a steel box with fins, where waste wood is burnt. The fins act as a big radiator in a second compartment where 2m3 of wood 2 IBC crates can go. In between the fins two greenhouse fans blowing warm air through the wood. We will build this and when we do will post pics

[sandbach-sticks]

Smee timber or whitmore's timber in winsford have just shut down three big timber kilns. I know they are going to scrap them, might be worth a call if anyone is thinking of drying serious amounts of wood.

[openspaceman]

Catweazel

 

Could you please explain a bit more on what system you put in to achieve a figure of £10 per tonne. I looked into various methods prior to going down the solar kiln route. To dry to 10% which I needed for production of wood pellets was going to cost 20% of sales value which is far higher than your figures.

 

I'm certain we didn't achieve the target figure of £10/ tonne of water removed. That was the best we expected to be able to do with the system built as conceived. In the event the customer dictated gasoil as fuel with little concessions to efficiency other than cladding it in 6" of rockwool. In effect they bought half of the dryer I intended but theirs was a very commercial decision and by all accounts worked well for them.

 

I had two linked goals 1 to keep running costs below £10/tonne of water removed and 2 to "spend" less than 4MJ/kg of water removed. I cannot remember exact figures but we would have been working on £0.04/kWhr for input energy. The trouble is an off the peg woodburner at the required 400kW put the capital cost up to0 much and the customer wouldn't accept a home brewed stoker burner. As with all plant the operating cost would have consisted of capital expenditure amortused, operational cost and fuel cost and charges on capital cost were the worry. All the detailed design was done by a colleague who was familiar with wood combustion, his degree was in a gasifying corn dryer.

 

Incidentally while this was going on another colleague (three of us formed the company) was "managing" the construction of the first dedicated pellet mill in Britain. As I recall, never having any hands on involvement myself, they used wood at 12% without the steam nebuliser and the pellets lost 2% through the die. At the time they expected to have a zero cost supply of waste sawdust which never materialised.

[Flyguy]

Some years ago I saw a timber yard / sawmill in central Germany with a need setup.

 

They had set up a wood trying kiln (insulated 40 foot shipping container) heated by the waste heat from a small diesel engine driving a genset. They ran it on on a heat demand system using locally pressed rape seed oil and fed the electricity back into the grid under the German eco feed in tariff scheme.