Dear Craig
----- Original Message -----
From: Craig Kernan
To: [email protected]
Sent: Sunday, February 03, 2013 2:32 PM
Subject: Re: [Gasification] mycoremediation of tarry water
Some possibly naieve questions a bit outside the box::
I assume we are considering mostly the cleanup of filters and equipment.
Can the chemical energy in these compounds be used in another process?
Is water the only solvent that can be used? (e.g. vegatable oil? .... )
Can the tars be captured is such a way as to become a useful fuel? (e.g.
fiber filters processed to? .... )
Craig
On 2/3/2013 9:50 AM, Kevin wrote:
Dear Stuart
----- Original Message -----
From: stuart mather
To: Kevin C ; [email protected]
Sent: Saturday, February 02, 2013 8:17 PM
Subject: Re: [Gasification] mycoremediation of tarry water
--------------------------------------------------------------------------
From: Kevin C <[email protected]>
To: stuart mather <[email protected]>; Discussion of biomass
pyrolysis and gasification <[email protected]>
Sent: Saturday, 2 February 2013 2:50 PM
Subject: Re: [Gasification] mycoremediation of tarry water
Kevin wrote:
....While I have not seen a report showing that blackwater disposal is
harmful to the environment, I have not seen one that says it is not harmful
either. However, a competent Gasifier Operator sent me pictures of his
blackwater dump site a few years after he stopped dumping blackwater there, and
the plants growing there seemed just as vigorous and healthy as nearby plants
outside teh dump zone.
>
> Best wishes,
>
> Kevin
That's intriguing Kevin,
So I wonder why there seems to be a general consensus that dumping tarry
water in a pond amounts to environmental vandalism. Not saying your gasifier
correspondent was making it up. But you would think the President of Myanmar
would have better things to do than declare black water gasification leach
ponds toxic sites Military juntas aren't well known for their environmental
awareness. So why the concern about tar ponds people?
Stuart.
# A "Tar Pond" or "Blackwater Disposal Pond" is a highly concentrated
"disposal situation". Too much of anything is almost certain to be a problem.
One cannot grow carrots or wheat in a pond used to dispose of distilled water,
and ethanol alcohol is a poison when taken in excess quantities at high
concentrations, as an extreme examples. The issues here are one of both
toxicity and concentration. A "Gasifier Tarpond" could indeed become qualified
as a 'superfund site." However, the same chemicals, if spread in dilute form
over say 1, or 10, or 100 square miles may present no significant hazard, and
may even yiled a net benefit.
# I would say intuitively that there is a combination of "toxicity and
concentration" above which, gasifire tar disposal is "bad", and that there are
"toxicity and concentration" combinations below which gasifier tars are not
hazardous, and may even be beneficial. I don't know all the compounds in
gasifier tars, and the concentrations below which they can be "generally
considered as safe." In my opinion, nobody can responsibly say for certain that
"gasifier tars are toxic" unless one specifies both the components and
concentration. Neither can anyone say for certain that "gasifier tars are
safe" unless one has a rational data base to support the statement.
# The process of smoking fish, meat, and other food products can be
looked on as a way to dispose of "gasifier tars." :-) The fact that such "smoke
tars" preserve foods proves that such tars are toxic to some life-forms. Some
studies suggest that smoked foods are bad, while others suggest that while
there may be some "cancer deaths" as a result of eating such smoked foods, the
benefits from reducing deaths from pathogenic organisms that would otherwise be
present greatly exceed the "smoking detriments."
# "The way to eliminate the gasifier tar problem is to eliminate tar
formation in the first place." This is not that difficult with properly
designed and operated gasifiers. This can be done, as is evidenced by the many
gasifiers in operation fueling IC engines, with no tar problems. Stratified
downdraft gasifiers, and updraft gasifiers are well known as "tarry gas
producers." In some applications, such gasifier systems can be very
appropriate, because of their generally lower capital cost, and their ability
to handle a wider range of fuel sizing and moisture content. Such gases can
often be burned directly, without need for tar removal. TLUD stoves, which are
basically "an updraft gasifier with a build-in burner to destroy the tars" are
an excellent example of a gasification system where tarry gas is not a problem.
If one wants to pipe such gas to a burner at a distance from the gasifier, then
tar build-up in piping is likely to be a problem. Water quenching of such gas
will remove many of the tars, ash and char that cause pipes to plug. Then one
has the problem and cost of dealing with the "blackwater." If the problem, and
cost of dealing with it are big enough, then it may be better to employ a
different gasifier, and different fuel preparation techniques, to produce a gas
with an acceptable tar level.
Best wishes,
Kevin
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