[Gasification] Mk2 Chip Guillotine

Kevin kchisholm at ca.inter.net
Sun Jan 26 17:32:44 CST 2014

Dear Darius

Firstly, I am assuming that you are measuring moisture % on the "Wet basis"., ie, 1000 kg of "wet" wood would have 
250/1000 = 25% moisture content Wet basis, WB, or 250 kG of water content. 

If you dry to 20% moisture content WB, you will have a "final moisture content" of .20 x 1000 = 200 kG water. You thus have to remove 250 - 200 = 50 kG water per tonne dried from 25% moisture WB to 20% moisture WB.

Each kG of water that you remove will probably need in the order of 1.2 kw-hr of thermal energy per kG of water "boiled off ". A tonne of wood feed at 25% moisture would need about 50x1.2 = 60 kw-hr to remove the required water from one tonne of wood feed. The wood will come out hot also... 950 kg of wood raised from say 20 C to 80 C would need about 
23 kw-hr of heat energy to raise the temperature of the wood. Total would be about 85 kw-hr per tonne of wood feed. 10 tonnes would thus require about 850 kw-hr of "input energy."

For simplicity, assume that ambient air is 100% saturated. Say tropic conditions of 30 C and 100% RH. 

850 kw-hr of thermal energy could be attained from wood that was burned at 80% efficiency; in this case "input energy would have to be about 850/.8 = 1063 kw-hr of "input energy." If the input wood had a moisture content of say 30%, then its heat content per pound of "as received" sawdust and bark would be about 14 MJ/kG, or 3.9 kw-hr per kg, indicating that you would have to burn about 850/3.9 = 218 kG of wood over the drying period. If you operated for 8 hours per day, you would need to burn about 27.24 kg of wood fuel per hour.... say about 30 kg/hr.

I would suggest that you take the flue gases and mix with ambient air, to have a "delivery temperature" of about 100 C, and blow it into your drier system. You have to be careful that you don't draw sparks from your combustion system, that could set your drying wood on fire. 

At this point, you have "adequate" hot air" to dry your wood chips. You could dry the "feed from the chipper" at say 10 Tonnes per hour, or you could pre-screen the chips, so that you only dried the chips that were sized to the desired final size range. 

Best wishes,

Kevin Chisholm

  ----- Original Message ----- 
  From: darius_tamizi 
  To: Doug 
  Cc: Discussion of biomass pyrolysis and gasification ; Discussion of biomass cooking stoves 
  Sent: Friday, January 24, 2014 8:00 PM
  Subject: Re: [Gasification] Mk2 Chip Guillotine

  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.



  Terkirim dari Samsung Mobile

  -------- Original message --------
  From: Doug <Doug.Williams at orcon.net.nz> 
  Date: 24/01/2014 14:26 (GMT+07:00) 
  To: darius_tamizi <darius_tamizi at hotmail.com> 
  Cc: Discussion of biomass pyrolysis and gasification <gasification at lists.bioenergylists.org>,Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org> 
  Subject: Re: [Gasification] Mk2 Chip Guillotine 


  You are a man of few words, or do they charge by the word for your phone(:-)

  What quantity are you talking about? 

  Biomass type wood/bamboo/brush wood,etc.

  Do you have any heat available?

  How do you currently dry chips?

  Scale is every thing, so simple cheap answers may not be available.


  On Fri, 24 Jan 2014 12:44:52 +0700
  darius_tamizi <darius_tamizi at hotmail.com> wrote:

  > Dear Doug,
  > The humidity here is 80% and more.
  > Darius


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