[Gasification] another aproach to producing a clean gas

[jim mason]

thanks for the hilsch vortex tube link.  i had never head of that.  very
interesting.

on the turn down rate / tar problem, i'm curious what the prior art is for
either bladder or high pressure tank storage of woodgas.  it seems that
several problems could be addressed here by the addition of a small onboard
storage system, with a pump mechanically driven off the engine (or a
secondary electrical pump).

imagine a pump/storage system that automatically started when the engine was
a idle, so as to maintain gas production, but to the end destination of
storage and not the engine.  such storage production would both maintain
gasifier rates, as well as provide a small storage pool that would be tapped
when high power is needed, and on start up when there is not yet any gas.
(and yes, obviously the pumping and storage will rob some energy)

it seems such a system, combined with the oxygen sensor auto mixture adjust
would go a long ways towards making gasifiers in mobile applications more
convenient for contemporay use expectations.  now admitedly, i am not a
promotor of convenience on most any front, but we must admit that gasifiers
are quite a long way from even veg oil systems in the ease of running them.


so i've been trying to think how gasifier systems might be more helpfullly
automated, with modest add on systems that don't increase complexity
greatly.

auto mixture control, and automated storage for surge and start up support
seems like a good starting point.

j
















On 6/3/06, drew <drew at artforging.com> wrote:
>
> 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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