This discussion has lost its focus. The question is not whether Oxygen is present but whether it is preferentially available to form the di-ether bonds that Dioxin requires, even before Chlorine enters the picture.
I have not puzzled through the reaction kinetics but it's obvious that you need two aromatic structures, two Oxygen molecules to join them (2X ether bond) and then (at most) four Chlorine atoms to alter the resonance of the bound benzenes. I guess intuition moves me toward Tom (Leland's) conclusion. There would need to be an immediate excess of Oxygen present; otherwise phenolics would be more likely to form than dioxins. All of this before Chlorine enters the picture. Mark Mark -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Sunil Rawal Sent: Sunday, September 19, 2010 10:58 PM To: Discussion of biomass pyrolysis and gasification Subject: Re: [Gasification] Dioxin formation Plasma gasifiction is process where temp is raised more than 1400-1500 deg cent. At this temperature which is known as plasma temp, all compounds are bound to disintegrate into their primary elements ( example;- CH3OH into C, H and O molecules). The process does not need oxygen. Sunil Rawal On Sat, Sep 18, 2010 at 7:27 PM, <[email protected]> wrote: > 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----- >>> Från: [email protected] >>> [mailto:[email protected]] För >>> [email protected] >>> Skickat: den 14 september 2010 21:00 >>> Till: [email protected] >>> Ämne: Gasification Digest, Vol 51, Issue 13 >>> >>> Send Gasification mailing list submissions to >>> [email protected] >>> >>> To subscribe or unsubscribe via the World Wide Web, visit >>> >>> >>> >>> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> >>> or, via email, send a message with subject or body 'help' to >>> [email protected] >>> >>> You can reach the person managing the list at >>> [email protected] >>> >>> When replying, please edit your Subject line so it is more specific >>> than "Re: Contents of Gasification digest..." >>> >>> >>> 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. >>> >>> >>> >>> ------------------------------ >>> >>> _______________________________________________ >>> Gasification mailing list >>> [email protected] >>> >>> >>> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> http://gasifiers.bioenergylists.org >>> >>> UNSUBSCRIBE HERE; >>> >>> >>> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> >>> >>> End of Gasification Digest, Vol 51, Issue 13 >>> ******************************************** >>> >>> >>> _______________________________________________ >>> Gasification mailing list >>> [email protected] >>> >>> >>> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> http://gasifiers.bioenergylists.org >>> http://info.bioenergylists.org >>> >>> UNSUBSCRIBE HERE; >>> >>> >>> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> >>> >>> >> >> -- >> _______________________________________________ >> Gasification mailing list >> [email protected] >> >> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> http://gasifiers.bioenergylists.org >> http://info.bioenergylists.org >> >> UNSUBSCRIBE HERE; >> >> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> >> >> >> _______________________________________________ >> Gasification mailing list >> [email protected] >> >> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> http://gasifiers.bioenergylists.org >> http://info.bioenergylists.org >> >> UNSUBSCRIBE HERE; >> >> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > >> >> > > > -- > _______________________________________________ > Gasification mailing list > [email protected] > http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > http://gasifiers.bioenergylists.org > http://info.bioenergylists.org > > UNSUBSCRIBE HERE; > http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > > > > > _______________________________________________ > Gasification mailing list > [email protected] > http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > http://gasifiers.bioenergylists.org > http://info.bioenergylists.org > > UNSUBSCRIBE HERE; > http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org > -- Achintya Projects & Services, 160 Evershine Mall, Near Mindspace Chincholi Bunder, Malad (west) MUMBAI 400064 INDIA Cell# 0091-9967064472 Telefax;- 0091 (0)22-42660929 _______________________________________________ Gasification mailing list [email protected] http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org http://gasifiers.bioenergylists.org http://info.bioenergylists.org UNSUBSCRIBE HERE; http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org _______________________________________________ Gasification mailing list [email protected] http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org http://gasifiers.bioenergylists.org http://info.bioenergylists.org UNSUBSCRIBE HERE; http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
