Hi Doug,
Thanks, yes we do have it sorted out and during our development years
playing with early packed beds have experienced most of the things you
observed. I recall an awful lot of bed profiling work looking at
particle distribution at different time and output changes to see what
was going on. However our mature system is not low temperature and no we
do not get torrefied chip out but rather a very high fixed carbon
charcoal (>85%) with little if any remaining volatiles. Tested gas
outputs show up to 55% combustible gas high H2, slightly lower but
roughly equivalent CO and less than 1% total CH4 and higher molecules.
Nowadays the systems are normally started on the char bed from the
previous run and on larger models if this is within twelve hours of
shutdown then engine grade gas is achieved within 2 minutes without need
for external re-ignition of the hearth. We have proven the design
parameters from 20kg/hr models through to 500kg/hr so far.
RE: Sydney; Yes the supplier was from Vermont. Our understanding is that
what was installed has never run on site and is being removed. We were
asked to come and "fix" it but we declined as we have already lost IP to
the people involved in the past and had no desire to be further
compromised, quite apart from the false assumption that our own systems
were sufficiently similar that we could just "tweak It". They lurk on
this list so given the saga is far from over and investigation
continuing it would be unwise to say anything further other than for
those contemplating a purchase please do your due diligence! And if
anyone claims to be the "originator' of our tech you can safely assume
they are lying.
On 3/14/2014 5:58 PM, Doug wrote:
Hi Peter and Colleagues,
As it happens, my work this last few months has been pretty involved around
these packed beds and charcoal, so naturally I am focus on how these differing
systems work.
On Fri, 14 Mar 2014 09:48:15 +1100
Peter Davies<[email protected]> wrote:
Thanks Doug, given the level of prior art reinventing the wheel is an
occupational hazard. Yes we have observed what you describe, the point
of differentiation though is where we were starting on straight (dry)
wood chips each run rather than charcoal from the previous run.
The key thing about all these systems is what your main need is from the
process. If you were planning on running an engine, then no way do you start-up
on raw fuel, as it will contaminate your gas cleaning system with tar. Process
heat and charcoal however is different, unless you have a blown system.
>It became clear that substantial improvements in gas calorific value and
useful volume were possible that we seemed to be missing out on.
Naturally raw fuel will always create high calorific gas, due to the pyrolysis
gases tar chemistry, and no oxidizing charcoal to create the necessary
exothermic heat, so you end up with a low temperature bed, higher carbon
content to the char, and a rich gas to burn in a furnace.
It was
study of this that led to the refinements in design we now enjoy the
benefits of.
As it may be of interest to others that, when you mix the phenomena of low
temperature packed beds with charcoal extraction, the raw chip is only torrified,
charred on the outside, raw on the inside. The low temperatures are around say,
<900C without free oxygen and a reducing atmosphere, enough to char and make
crude gas, as the hydrocarbon content is still locked inside. As the chip drops,
the 900C gas flow sets the conditions that fix the hydrocarbons, hence the better
char. If you want to improve the gas quality, because it will be low in H2 but
have CO,CH4,C2H5/6 from being low temperature distillation gases released from the
surface charring, you need a deeper bed to increase the contact time, BUUUT, if
you do this, you begin to initiate CO reversion into soot and CO2 while the bed is
above 500C Then if your char extraction rate is not quite right, you can also get
H2 reversion and are back to mediocre gas.
Peter has obviously sorted this out, but more than a few are chasing shadows
for the wrong reason. I heard a whisper that there is a failed gasifier project
in Sydney Australia, supplied from a USA manufacturer. Can anyone of our Forum
members offer more comment about this project?
Doug Williams,
Fluidyne.
--
Peter Davies
Director
ID Gasifiers Pty Ltd
Delegate River, Victoria
Australia
Ph: 0402 845 295
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