GEK Wiki / Horizontal fuel feed auger add-on
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Horizontal fuel feed auger add-on

Page history last edited by jim mason 15 years, 1 month ago


Here's our new automated fuel feed and fuel drying / preheating system for the GEK.  The controlled feed and thermal "pretreatment" of incoming fuel is a very old idea in gasification.  The problem has always been the method to implement it economically.  The solution below uses the typical GEK tube in tube with flange building system to make double jacketed heat exchange system with a simple spiral rod auger to move the fuel  Provisions for a stirring rod drive are also provided in the center of the reactor lid.  We can now provide these add-ons for the GEK in both fully fabricated and parts only forms.  Drawings to make your own will be up soon. 




Update 4/7/09.  We've now altered the above so as to make a shorter auger and taller hopper bucket.  Increasing the amount of hopper bucket favors putting heat into the monorator condensing/drying cycle above the hopper bucket, thus removing water from the fuel.  The longer auger favors vaporizing and heating the water, then sending it into the reactor.  After some discussion of the first prototype, we've modified it towards favoring drying and water elimination, thus the taller hopper bucket and shorter auger.  We've also moved the auger motor to the hopper bucket side, which simplifies various things a bit.











full res image: auger-hopperbucket-lid-3D_vB.pdf


More details on why


A controlled feed system creates the ability to vary fuel rate into the reactor in relation to actual gas production needs.  A pile of raw fuel sitting on top of thermal mass in the reactor is pyrolyzing even if you are not pulling gas.  You can easily get a tar bloom far in excess of your tar gas needs for combustion.  Thus varying your fuel in feed rate can better match pyrolysis rate to combustion/reduction rate.   At the same time, the system allows for much cleaner start ups and shut downs, as you can stop the feed and empty raw fuel from the reactor before shut down.  The combined benefits are akin to the fully automated pellet wood stove.


Integrating a fuel heating system into the fuel feed system opens up many possibilities for reducing the extreme moisture sensitivity of closed top Imbert type gasifiers.  The thermal drag on combustion from moisture in the fuel can quickly overwhelm proper tar cracking in the combustion zone.  Vaporizing this moisture and beginning its heating to combustion temps can do much to increase the moisture flexibility of the gasifier.  Heat is available to do this work both from the output hot gas from the gasifier, as well as from the exhaust from an internal combustion engine run off the gasifier.


The combined fuel and water vapor represents a much larger heat carrying media that the incoming air.  The GEK air preheating system is ultimately undefined limited in the amount of heat it can return to the reactor, by the relatively small heat carrying capacity of the incoming air.  The incoming fuel and moisture under typical operating conditions has about 3x the heat carrying capacity (or drag) as the incoming air.   For details on this, see our ongoing work in modelling gasifier energy balance here:






Another option for the future?


We could elaborate the above basic solution with a "flange to flange" port coupling system to transfer gas between the reactor and auger housing.  Typical external plumbing circuits are eliminated, and the gas simply travels upward inside the annular space between vessels, then through ports in the flange faces.  Think the water jacket joints between the block and the head on a V-8.  Engine design made this transition from external oil and water distribution to internal block/cylinder/head distribution right around WWII, I believe.   Gasifiers haven't had another round to catch up, until now.


This internal gas distribution system also returns the rising product gas heat to the pyrolysis and drying walls in the reactor, somewhat like the original Imbert heated hopper. 


The annular hat on the reactor, or base under the hopper, can also second as a packed bed filter space, thus eliminating the external filter vessel.







See full-resolution image here: AugerHousing.pdf




Comments (4)

seachanged said

at 10:17 am on Apr 5, 2009

What are the power requirements of that motor? AC? DC?
What kind of torque will that auger feeder tolerate?
Is there non-destructive jam protection mechanism (like a shear key)?

Alan Jones said

at 11:10 pm on Apr 11, 2009

what will Allpower charge for one of these? will thse make chip burning possible? are they available now?

Johnny Payphone said

at 4:09 pm on Oct 19, 2009

The augur add-on is available now and runs $595 unassembled and $995 assembled.

Johnny Payphone said

at 4:22 pm on Oct 19, 2009

We ship a 12 v DC Wondermotor from Its torque is rated at 11.5 N-m (8.5 ft-lb). We find that it pushes woodchips just fine. There is no shear key, and so we have designed the spiral augur to fail in case of a catastrophic jam, to prevent motor burn-out.

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