[Gasification] another aproach to producing a clean gas

[drew]

Hi Andy,

    Sounds like a great setup, I have a suggestion for cleaning up the 
gas stream.   It may be difficult for you to impliment , but if your 
wood hopper is truely air tight, maybe not.   Some people may also see 
it as inefficent, but for my purposes (stationary engine) it isn't as I 
will explain.

    Imberts can provide a clean gas stream only if the gas flow rate is 
matched to the fuel, and equiptment setup.   If as you say, idleing 
produces fouled plugs then perhaps you are trying to run at gas 
production rates below what your setup can produce cleanly  (you might 
want to start by seeing if your reactor tube temperature is dropping).  
What I have some sucess with  (not with an imbert) is keeping the gas 
flow constant by shunting gas to a flare (will be my water heater) when 
my load is not present.    I use a pressurized hopper (2psi) and produce 
gas at a steady rate almost regardless of load in my system,  that makes 
it realitively easy for me.   This keeps the flow rate through the 
gassifier consistant.     I have thought that in a vacum "driven" imbert 
perhaps if you were to install a one way valve on the air flow to the 
tures so that air could only be drawn there then you could feed low 
pressure air to your hopper, or the tures directly, then have a vacum 
switch on your intake manifold of you engine that would open your flare 
valve (you would need a pilot of course, but water heaters need a pilot 
anyway).     There are probly other ways to impliment this, but the idea 
is just to keep the gas flow more consistant, especialy at low rpms on 
your engine.    One thing to keep in mind here is that vacum drawn 
systems are inherently safer, in that any leaks in the system will only 
draw in air, but in a pressure driven system if you have leaks you will 
likely leak flamable gasses, including the deadly CO, take extra care. 
   In the setup I am describing, your system would only be a pressure 
system at low rpm, it would revert to a vacum system when you increase 
rpm enough to suck the one way valve open.       You might also want to 
try a smaller diameter and possilbly longer reactor tube or a tube made 
of refractory?  but I would ask Doug W. at fluidyne about that?  I have 
also wondered about the idea of using refractory "balls" in the bottom 
of the reactor tube to increase the gas dwell time in the high 
temperature zone, they would have to be large to allow lots of space for 
ash to drop around them but if you have a grate shaker, or are in a 
moving vehical it might be a way of keeping the gas exposed to heat for 
a little longer (to give the tar more time to crack).  

Recently I have been wondering about including a hilsch vortex tube as a 
molecular "sorter" if it can sort hot air molcules from cold,  perhaps 
heavy from light eg, tars from hydrogen CO?     I know that there is 
another venturi like device that can do this, but it seemed to be quite 
tight tolerance, this seems a little looser.   If anyone out there knows 
more about the other venturi system perhaps send me a link?
http://www.visi.com/~darus/hilsch/ <http://www.visi.com/%7Edarus/hilsch/>

keep on truckin
Drew

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