[Gasification] the most important thing (quite possibly) > > i've learned to date

andy schofield scothebuilder at hotmail.com
Tue Oct 19 09:32:44 CDT 2010


 A few years ago, I placed a bushel of cherry pits dripping wet fresh from the orchard  in a 30 gallon bin. Truck exhaust was led in the bin beneath a perforated cone with the truncated apex leading to a drain valve. Gravity flow from the drain valve yielded a slug of charred pits after driving aggressively around on hilly country roads for 6 miles.

  Vast clouds of water vapor issued from the top, so I deemed it to be a safety hazard for cars behind me. In a stationary plant, this will be less of a problem most days here in in the Mackinac. I would not recommend any additional water for an imbert type gasifier.  Careful monitoring of exhaust-valve temperature is recommended for otto-cycle engines.

 Oxygen in the exhaust may account for the  black charring I found in a portion of the bushel, in spite of closely trimmed exhaust excess oxygen by the Ford engine control module. Flushing out water vapor, greater distribution, and attenuating bed-temperature with forced-draft ambient air will see great advantage in this biomass-roaster.

 Friends operating direct gas-fired corn dryers find fuel useage is lower on days with low ambient humidity. They say bin fires have happened to others that have fallen asleep at the throttle. The main thing is to have a place to dump burning corn, and have much fire-fighting water ready. Storage-bins need to well sealed to the air. Sample your product continuously. Enough safe farming tips, for now.
  Diesel-cycle and especially the rankine cycle have much more excess oxygen in exhaust. Combined-cycle gas turbines usually employ fueled duct-burners at the inlet to HRSG, to take advantage of the percentage of heated O2 (and nitrogen) in the engine exhaust.

 A Just in time supply of wood must certainly be well insulated to prevent loss.

Using a short auger has certain inter-bin sealing issues, I've found.
A star-valve, or disc-feeder is suitable for only a round particle; like dry pits, and custom made lip-seals wear quickly. 
Carefully lapped bin diameter full-bore hydraulic-gate systems need to be looked into seriously for particles that tend to bridge.
Another type of valve I will not talk about until I can afford improved materials may provide positive inter-bin sealing.

All volatiles should not be driven from the wood, because burning certain ones directly in front of imbert nozzles is what drives the entire wood gasification process.

Again, I always get much water in the hotwell of my gas-cooler. Hydrogen production probably has limits in my stuff because of the time given for hot-char contact.

Andy Schofield

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