James,?
We have had extensive testing done or dioxins on MSW/RDF gasification
and in the critical critical areas, did not ?have detectable levels. The third
party work was done by Los Alamos National Labs, San Diego's consortium of
waste management, ?Sandia National Laboratories and Radian, the same
technician/engineer for Radian that prepared an exhaustive analysis for DOE
that was the technical basis for US ?EPA to try to get refinery waste
gasification exempted from RCRA, but hasn't happened yet.?
A technical evaluation of gasification shows that without oxygen the
basic reaction of Cl+O2->ClO2 doesn't occur and hydrogen will strip the O2
from chlorine compounds already formed, preventing he dioxin formation and
breaking down any dioxins introduced to the system. This has been discussed
here before.?
?A GC cannot be used for metal analysis, at least none of the ones I
have been exposed to.?
Not using a qualified technician may allow the regulators to throw out
the results.?
?
Sincerely,
Leland T. "Tom" Taylor
Thermogenics Inc.?
-----Original Message-----
From: James Joyce <[email protected]>
To: gasification <[email protected]>
Sent: Sun, Jun 29, 2014 2:49 am
Subject: Re: [Gasification] Dioxins ...was Clean air ..
Leland, regarding costs. I have had two scenarios described to me, one where
the
sample device is provided and I take the sample (therefore up to me to make
that
representative) and one where a technician comes in to collect the sample. I
believe the $3000 applies to the first case ... ie. sampling is an additional
cost.
If you are referring to on-line or at-line GS-MS or Gel chromatography I am
interested to hear about experiences with these techniques. Our plant operators
are not qualified instrument techs or lab techs ... which means at best the
devices would get a check over on a monthly basis during scheduled plant
visits.
My interest in the bag filter was with respect to particulates. This relates to
dioxin in that they tend to be adsorbed onto the particulates (although perhaps
more so at <300 deg C than 600 deg C), so it is one way to remove dioxins
and
their precursors if they are present. Some plants I understand actually inject
fine carbon into their flue gas for this very purpose.
Kevin, on your comments about Chlorine and copper, I have been maintaining a
watching brief for some time on the topic and from what I understand Chlorine
levels are in fact poorly correlated with Dioxin emissions, arguably because
the
chlorine levels in most feedstocks, even at ppm levels are many many times the
quantity needed to make the tiny amounts of Dioxins that regulators are
checking
for. I read a very good review of the science just last week. If anyone wants
the reference I could dig it out next week. The review of a looked critically
at
a variety of data on Dioxin formation and control. My interpretation of the
their conclusions is that Dioxin emissions from pyrolysis, gasification and
combustion processes are:
(a) Very poorly correlated with Chlorine levels, with the exception of a few
industrial chemicals (not biomass)
(b) Strongly correlated to completion of combustion and the residence time of
flue gases between 200 - 400 deg C (the desired residence times in this range
were less than 1.6 seconds ...which perhaps does not bode well for torrefaction
! ... and hot running electrostatic precipitators)
(c) Catalysed by copper and copper compounds .. which in turn are inhibited by
the presence of sulphur.
(d) Sometimes dictated by the dioxin content of the incoming feedstock rather
than formation in the process
If anyone has done Dioxin measurements on flue gases from thermal processing of
biomass I certainly would be interested in their experiences.
Regards,
James
------------------------------
Date: Sat, 28 Jun 2014 05:50:23 -0400 (EDT)
From: [email protected]
To: [email protected]
Subject: Re: [Gasification] Clean Air Regulation requirements imposed
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
James,
The price you stated for a dioxin test is just the analysis and does
not
include the technician's travel time, set up time and sampling time, per US
costs.?
There is a method of on-stream continuous measurement that will give
analysis
of all of the compounds presented in the standard you referenced that will also
include fixed gases to almost any molecular weight.?
I can't see how any bag or filter can be used to clean the gas.?
Sincerely,
Leland T. "Tom" Taylor
Thermogenics Inc.?
Date: Sat, 28 Jun 2014 09:22:55 -0300
From: "Kevin" <[email protected]>
To: "Discussion of biomass pyrolysis and gasification"
<[email protected]>
Subject: Re: [Gasification] Clean Air Regulation requirements imposed
Message-ID: <CE1F1C69726943FCAC3E73C36F829823@usera594fda0bf>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Dear James
It is my understanding that if Chlorine is present in a "biomass pyrolysis
situation", the presence of dioxins is virtually guaranteed.
For example, if yak or cattle dung, chicken or feedlot manure, or salt water
driftwood are pyrolysed or partially burned, there will be dioxins in the
resulting pyrolysis gases or smoke.
QUANTITATIVE testing for dioxins could be very expensive, as you suggest.
However, QUALITATIVE testing can be very low cost. Simply heat a copper wire
red hot in the presence of the gas being tested for dioxins, when chlorine
gas or chlorofluorocarbon refrigerants are known to be absent. If dioxins
are present, the flame turns green or blue-green.
Best wishes,
Kevin
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