[Gasification] Mk2 Chip Guillotine
Doug.Williams at orcon.net.nz
Sun Jan 26 14:38:00 CST 2014
Hi Darius and Colleagues,
How are you drying the chip the chip at this time, even if it is slow?
I have been working up a concept for many years to dry chips, and one of the mental tricks I use is to change all the numbers involved, and break them
down into a physical measurement of chip volumes. I guess your day is an 8 hour unit, and not 24, so your 10 ton at say (roughly) @ 4 M3/T = a flow
rate of about 1,250 ltrs/hr = 20 ltrs/min, in physical volume, that is only 4 buckets/min. (bucket defined as a 20 ltr or 5 gallon container).
I used to dry 20 ltrs of chips for trial in an old tumble close dryer, and was surprised at how well this worked, and could see that a multi pass rotary system had considerable potential. This would be a series of large diameter tubes inside each other on a adjustable incline. The chip enters say the
outer at the bottom, tumbles to the top dropping into the next tube, then drops back tumbling to the bottom, then into the next tube an up again in a series of zig-zags. Spacer plates along the tubes act as spiral paddles so the chip can be carried evenly around the tube and not just sit in the bottom
as a slug. Lengths of the rotary tube need some thought relating to how much time it takes for the chip to heat right through at X temperature. The variation of chip sizes will see the smaller dryer chip travel faster, so a degree of risk from over heating is controlled. With this in mind, the
velocity of the air flow rate through the final chip tube will have relevance to the tube sizing so nothing is going to be small in size.
How the hot air might be introduce and discharged is a key question, but there might be some merit for the hot entry to be at a sealed discharge end with
a simple flap or rotary valve system for the chip exit. The hottest air will finish the chip on it's last pass, and the very humid hot air exits through the wet incoming chip. Doing it this way, the fastest moving dry chip has the least amount of time in the hottest air flow with less risk of spontaneous combustion.
This is a mental concept, and can now be pulled to bits by anyone who already knows why it cannot work(:-)
On Sat, 25 Jan 2014 07:00:57 +0700
darius_tamizi <darius_tamizi at hotmail.com> wrote:
> Dear Doug, Kevin,
> We need to dry 10ton of wood chip daily (all kind of tropical wood).
> We can burn Bark, sawdust and biochar as the heat source.
> Today we are using waste heat from the gasifier for drying the woodChip. For drying 1ton of woodchip from 25% to 20% we need 4-8 hours with the system. It is too slow.
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