[Gasification] another aproach to producing a clean gas

Sat Jun 3 18:39:53 CDT 2006

Dear Max:

Where is the annual woodgas jamboree held and can you send us a 
description and report when you return...

Yours truly,

TOM REED               GASIFICATION

gasman wrote:
>
> To Jim Mason
>
> There are two fundamental factors, that make the
> idea of "storing" woodgas on a vehicle unrealistic:
>
> 1. CO will "fall apart" (more complicated?) when compressed:
>    CO ==> CO2 + C.
>
> 2. As the heating value of woodgas is low, the amounts
>    for a reasonable using time are huge; the motor supposed
>    to go idle, will have a heavy job in driving a compressor
>    "for almost nothing"... back! But of course the draft in the
>    gasgenerator will be kept up.
>
> Energy-vice it would be easier to use an electric ventilator
> to supply a torch, or some useful heating.
>
> Still, these are only handling the symptoms, and covering up
> the real reasons!
>
> During the WWII a turn down ratio of 18:1 was achieved
> just by taking care of good insulation, so there is a lesson
> to take after!
>
> Now, a natural addition is to take care of good heat-exchange
> from the ready made raw-gas to the primary air.
> Another prominent factor is to dry out both physical and
> the greater part of the "chemical water" from the fuel, before
> it reaches the hearth.
>
> That makes a better starting point for making good  gas, even
> with increased turn down ratios.
>
> On my way today 4.6.2006 to the yearly woodgas jamboree...
>
> Max
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> ----- Original Message ----- From: "jim mason" <jimmason at whatiamupto.com>
> To: <gasification at listserv.repp.org>
> Sent: Saturday, June 03, 2006 9:55 PM
> Subject: Re: [Gasification] another aproach to producing a clean gas
>
>
>> 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
>>
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>> 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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