Smoke, then fire!

I burned biochar in mid-January the other day. Very rare for me. Usually we are very wet now, but we're in the middle of a dry spell, so I thought I'd take advantage of it.

As sometimes happens, it was burning along and then it turned to just smoke. I get worried when this happens. Sometimes in the past it has lasted several minutes, churning out smoke and no real fire.  This is the opposite of what I want.  I'm burning a TLUD 55 gallon drum with a chimney.

I decided to throw a piece of waste paper in the top.  It burned and it reset the rest of the barrel to start burning again. It continued to burn for the rest of the time.   I had a sense that with a TLUD, there needs to be a flow of burning of the gases off the wood as it goes up the chimney.  My guess is that it reset that flow.  

I'm curious as to whether someone else might have more insight into what happened.

Thanks,
John S
PDX OR

My guess is that even though your weather has been abnormally warm and dry, the feedstock moisture content was higher than optimal. I've had lots of TLUD burns fail or go smoky because of this. Once it was a bag of wood pellets that had been rained on and the person who loaded the barrel had poured them in anyway, then poured a nice dry bag on top. The burn started off great, but as soon as the combustion front reached the ever so slightly damp layer it was game over.

If you can fix it with a bit of paper or cardboard then it's not too bad. What is probably behind it is that extra load of water vapour in the flue gas is condensing and stalling the flow up the stack, so getting the extra push solves the symptoms enough to keep going.