[Gasification] Tuning an Imbert type

[Thomas Reed]

Dear Andy and All:

Thanks for your description of the Imbert and stratified downdraft 
gasifiers for cherry pits.  We have 8 tons of your pits, so are 
particularly interested in your success.  We have been running our 
modified stratified downdraft primarily on acai pits, a VERY different 
fuel from cherry pits (16 MJ/kg vs 21 MJ/kg for cherry pits).  Glad to 
see that the pits are driving the 5.7 L engine.  The Imbert gasifier has 
a lot to recommend it, particuarly a million users 50 years ago.  Where 
did you get the Imbert reactor you are using and what are its critical 
dimensions?

An important part of the tuning is the selection of the right size 
gasifier for the engine.  In our book Handbook of Downdraft Gasifier 
Engine Systems (available at www.woodgas.com) we have the recommended 
dimensions for various gas outputs in Table 5-2, p. 27.  The most 
critical size is the choke plate (can be a 14" thick washer in the 
firetube) and fortunately it is the same for gasifiers generating 120, 
150, 190 and 230 m3 gas/hr.  Your 5.7 L (350 CI) engine could use 120 
NM3/hr, generating 200 kW (6MJ/m3X120/3600) or 270 HP.  (Sound right?)  
In that case, the firetube is 40 cm in diameter and the ID of the choke 
plate is 13 cm.  (If this is too small, you can easily change it for the 
higher gas production rates.  The nozzle inside diameters for this size 
choke is 10.5 mm. 

Yours truly,

TOM REED       BEF




andy schofield wrote:
>
> Dear All,
>
>  This past week, I've been running my gasifier with a few  
> modifications. The stratified downdraft reactor unbolts from the 
> grate-flange and the gas clean-up train. I set it aside and fitted an 
> Imbert-type reactor with an air-tight fuel batch-bin with condensate 
> trapping slotted liner (monerator).
>
>  The 500 pound unit is now mounted aboard a 1975 GMC 1/2 ton cab and 
> chassis. The 5.7L V-8 is fueled with both gasoline (4-barrel 
> Rochester), and the gas made from cherrypits.
>
>  The gas-train consists of a 30-gallon hopper-bottom hand augered 
> ash-bin, a nominal 4" cyclone,
> a 30 square foot surface water-cooled gas cooler, and a large 
> straw-packed filter. Electrical auxilliaries are driven by a 4KW 
> gasoline genset.
>
>  Top speed so far is 40 MPH on a 1/3 mile rough dirt oval track 
> (gasoline throttle shut). This breaks my own old speed record I set in 
> 1991 with a four-cylinder Jeep side-valve,  also fueled (stratified 
> downdraft) with pits.
>
>  Sparkplugs tend to foul at low gasification rates, but I have a way 
> to clean them. Anyone have suggestions to tune an Imbert type for less 
> tar?
>
>  The purpose of this setup is to tow a 3.5 ton trailer at the lowest 
> cost possible. Break-even point is many miles down the road! Keep you 
> posted.
>
> In the "pits" wrench'n.
>
> Andy Schofield
> Great Lakes renewable fuels (and systems)
>
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