[Stoves] combustion of char

[Frank Shields]

Stovers, 

FYI
After having about 30 compost samples in a drying oven go up in flame it
looked like it started with a single char sample placed in the corner. I
decided to do a little research by asking Hugh McLaughlin. Another question
I had for him was why does some biochar samples gain weight in a drying oven
set at 105c. 

So it seems soon after a char is produced it wants to take up oxygen. If
bagged in a sealed container and sent to the lab soon after being made the
dry sample will take up oxygen in the oven therefore gaining weight. If a
sample is wetted soon after being made the water prevents oxygen from being
taken up. Then if it becomes dry it wants oxygen, increases temperature and
can catch fire under the right (wrong) conditions. Char is a great insulator
so the heat can be trapped and build up. If there is organic materials
around it can flame. So before storage better give it time to take up
oxygen. Or if wetted do not let it dry out and keep bags of char in single
layers.     

The forced air drying oven was left on overnight and it was in the morning
we found all the burned up samples. It was placed against the wall so we are
lucky we still have a lab!

Regards

Frank