It is doubtful that temperature has anything to do with oxygen presence
in the case of plasma gasification. If there is free oxygen in the
gasifier environment at the chlorine release stage of heating, then the
gasifier is not working as a gasifier, but as a combustor. At the
temperatures of the syngas or producer gas in the gasifier, dioxins
would still be stripped of their oxygen by the hot hydrogen in the gas.
There are significant references to these effects including an Indian
research report which shows the reduction of dioxins from feeding black
liquor into a gasifier.
Sincerely,
Leland T. "Tom" Taylor
President
Thermogenics Inc.
-----Original Message-----
From: Sunil Rawal <[email protected]>
To: Discussion of biomass pyrolysis and gasification
<[email protected]>
Sent: Fri, Sep 17, 2010 11:48 pm
Subject: Re: [Gasification] Dioxin formation
I would say that in practcal way there is always presence of oxygen
except
in case of Plasma gasification where temp is very high. If sufficient
oxygen
is not there then full burning is not possible and till date there is no
system available which can mix fuel and oxygen perfactly.
Sunil Rawal
Achintya Projects & Services,
160 Evershine Mall, Near Mindspace
Chincholi Bunder,
Malad (west)
MUMBAI 400064 INDIA
Cell# 0091-9967064472
Telefax;- 0091 (0)22-42660929
On Fri, Sep 17, 2010 at 8:42 PM, <[email protected]> wrote:
As part of the intermediate step to formaiton of dioxins, it is
necessary
to form chlorine dioxide. In the strongly reducing hydrogen rich
environment
of the gasifier, the oxygen is removed so that this intermediate is
not
formed and dioxins are not formed. In fact, gasifiers are a good
method of
reducing dioxins.
Sincerely,
Leland T. "Tom" Taylor
President
Thermogenics Inc.
-----Original Message-----
From: Sunil Rawal <[email protected]>
To: Discussion of biomass pyrolysis and gasification <
[email protected]>
Sent: Fri, Sep 17, 2010 12:10 am
Subject: Re: [Gasification] Gasification Digest, Vol 51, Issue 13
Dear All,
Technically to avoid dioxine, we should prevent reaction of halogens (
Florine, chlorine, Iodine, Bromine) with nox and the temperature most
suitable for it is around 330 to 280 deg cent. So whether you burn
material
in incinerator or plasma gasification process or your normal furnace,
if
you
can aviod the said temperature zone in flue gas by sudden cooling or
maintaining flue gas above 330 deg cent. to avoid formation of
dioxines.
Another method is scrub out these halogens from gas at higher
temperature
to
avoid formation of dioxine.
As formation of dioxene & PCB is based on halogens if raw material is
free
of halogen compound, there is no need to take care of temperature
zone.
I have worked and studied a lot on these issues and what I said above
are
only way to avoid
formation of dioxene.
Anybody interested in more information may contact me on my email id
[email protected].
Sunil Rawal
Achintya Projects & Services,
160 Evershine Mall, Near Mindspace
Chincholi Bunder,
Malad (west)
MUMBAI 400064 INDIA
Cell# 0091-9967064472
Telefax;- 0091 (0)22-42660929
2010/9/15 Björn Dahlroth <[email protected]>
A very important source of chlorine in municipal solid waste is simply
foodstuff that contain ordinary table salt. At high temperature
sodium
chloride will dissociate. The trick to avoid dioxins in the exhaust
from
modern incineration plants is first to achieve as complete combustion
as
possible and then quick cooling of the flue gas to decrease
recombination
plus the use of absorption materials and catalysts. This is common
technology today. Thermal gasification would probably be another
story but
the important thing is what you get when you finally burn the gas.
Anyways
if you work with waste like MSW the plants have to be very big for
economical reasons and gasification followed by any thermal
electricity
production will hardly achieve a higher total efficiency then a
modern
incineration plant where you have pressed up steam data to the
possible
limits with such kind of fuel. It is also an unavoidable fact that
with
common market price levels for electricity or combined electricity
and
district heating it will be necessary that waste treatment plants
charge
some kind of gate fee. This is what we have to pay to achieve a very
low
pollution of the environment.
Bjorn Dahlroth
Sweden
-----Ursprungligt meddelande-----
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Skickat: den 14 september 2010 21:00
Till: [email protected]
Ämne: Gasification Digest, Vol 51, Issue 13
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Today's Topics:
1. Re: Does anyboday know GEM3T120, waste gasification (Max Kennedy)
2. Re: Does anyboday know GEM3T120, waste gasification
([email protected])
3. Re: Does anyboday know GEM3T120, waste gasification (Arnt
Karlsen)
----------------------------------------------------------------------
Message: 1
Date: Mon, 13 Sep 2010 16:56:48 -0700 (PDT)
From: Max Kennedy <[email protected]>
To: Discussion of biomass pyrolysis and gasification
<[email protected]>
Subject: Re: [Gasification] Does anyboday know GEM3T120, waste
gasification
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
Dioxins are formed from chlorinated and organic compounds not
nitrogen
containing compounds. Vinyls are especially bad.
________________________________
From: Arnt Karlsen <[email protected]>
To: [email protected]
Sent: Mon, September 13, 2010 1:36:20 PM
Subject: Re: [Gasification] Does anyboday know GEM3T120, waste
gasification
...
..they and dioxins etc are produced when you burn fuels
containing organic nitrogen compounds.
------------------------------
Message: 2
Date: Mon, 13 Sep 2010 22:38:04 EDT
From: [email protected]
To: [email protected], [email protected]
Subject: Re: [Gasification] Does anyboday know GEM3T120, waste
gasification
Message-ID: <[email protected]>
Content-Type: text/plain; charset="UTF-8"
from Lewis L. Smith
As I recall from my "boiler" days, the production of dioxins can be
avoided
in combustion processes by ?
[1] Removing chlorinated materials from the feedstock.
[2] Controlling temperatures, especially those of combustion and
stack
gasses.
[3] All of the above.
###
------------------------------
Message: 3
Date: Tue, 14 Sep 2010 13:48:00 +0200
From: Arnt Karlsen <[email protected]>
To: [email protected]
Subject: Re: [Gasification] Does anyboday know GEM3T120, waste
gasification
Message-ID: <[email protected]>
Content-Type: text/plain; charset=US-ASCII
On Mon, 13 Sep 2010 16:56:48 -0700 (PDT), Max wrote in message
<[email protected]>:
> Dioxins are formed from chlorinated and organic compounds not
> nitrogen containing compounds. Vinyls are especially bad.
..correct (some of these contain nitrogen ;o)), they are
broken down in a gasifier in about the same way, though.
..some (Danish?) R&D people played with FeCl type acids
in char beds to break down freon type gases, I read this
years back doing "my homework" on my own gasifier.
--
..med vennlig hilsen = with Kind Regards from Arnt... ;o)
...with a number of polar bear hunters in his ancestry...
Scenarios always come in sets of three:
best case, worst case, and just in case.
------------------------------
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