[Gasification] Chip drying without pyrolysing; Biocoal manufacture.

Doug Doug.Williams at orcon.net.nz
Sat Jan 25 14:12:00 CST 2014

Hi Tom and Colleagues,

Having spent the first 9 years of my "trade "life in transport engineering, your idea is sound but difficult to put into practice. Chip trucks are tippers, so the exhaust would have to enter the box via a flexible hinge at the rear of the body. Not impossible, but difficult to organise as most exhausts exit vertically up the back of the cab. You would then need a body floor that is probably perforated, or for trials fitted with a piping system on top of the floor.

Having used exhausts a lot over the years into drum driers, but not closely controlled to 300C, but around 300C just the same, given enough time, the chip on the bottom starts to cook, and you see this at a point when steam and blue smoke comes out the top. This is much the same problem for any static pile, so introduces the need for chip movement. Rotational drying is a known technology, but in the circumstances that we might dry chips for gasification and whatever, I have often thought that our primary sources of heat is slightly different in it's acquisition to those of most commercially available dryers.

While we continue to seek easy solutions and simplicity of design, the answers to these questions remain complex for those charged with resolving the problems. The calculations may show what might be possible, but it doesn't tell you how it's achieved(:-)

Doug Williams,

On Fri, 24 Jan 2014 08:27:58 -0500
Tom Reed <tombreed2010 at gmail.com> wrote:

> Here's a simple solution, and I hope someone will try it before I need to.  
> If you are transporting the chips any distance by truck, 2/3 of the truck's fuel goes out the exhaust pipe as heat, enough to dry a load of chips the truck is carrying.  The temperature of the exhaust is closer to 600C as it leaves the engine, too hot for drying.  But if air is aspirated into a side stream of exhaust the ratio of exhaust heat to added air could be adjusted with a simple spring thermostat to 300 C (or other as required) to "cook or cool" the wet chips without overhearing them.  There is plenty of exhaust pressure available for the aspiration before the muffler, and the drying would muffle this side stream as well.

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