[Gasification] Chip drying without pyrolysing; Biocoal manufacture.
tombreed2010 at gmail.com
Fri Jan 24 07:27:58 CST 2014
The question of how to easily dry green wood chips addresses one of the most important problems in wood energy: how to dry green chips! Wood is much easier to chip wet, but a chip pile never dries of its own accord.
On an experimental scale, of course, you can put them in an oven at 120C* (250 F) and keep a glassed eye on them for as long as it takes to pass the following test: stand in front of the oven wearing glasses. Open the oven a few inches, and let the hot, moist air escape and strike your room/body temperature glasses. If they cloud up, the chips ain't dry; if they stay clear, you are bone dry.
And of course, avoid too high a temperature, because the pyrolysis of wood becomes exothermic around 300C, and the wood will take itself up to 400-450C without asking permission.
*Does anyone have an idea of the BEST temperature for drying without pyrolysing? We have all learned here that 300 C (572 F) converts the wood to biocoal with an energy content of 10-11,000 Btu/lb, driving off all water and a lot of extraneous CO2, and not much H2, methane and CO. This product has been defined here as Biocoal. Good stuff, and I hope those with more experience will weigh in again on Biocoal.
Briefly, on the subject of biocoal, there is a double problem: heating it rapidly and efficiently to 300C, and NO MORE, even though we are on the edge of the exothermic reaction zone.
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.
Your biomass/biochar/biocoal booster,
Thomas B Reed
280 Hardwick Rd
Barre, MA 01005
508 353 7841
> On Jan 24, 2014, at 2:26 AM, Doug <Doug.Williams at orcon.net.nz> wrote:
> 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.
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