[Gasification] "Continuous analysis of elemental emissions from abiofuel gasifier"

[James Joyce]

Tom and Leyland I agree with your comments. In the work I did with 
sugar cane bagasse for my PhD I belive I found that metal species 
migrated into the silica structures of the cane and formed low 
metaling temperature silicates. These were mostly iron and aluminium 
silicates. These showed sintering (melting) behaviours at 
temperatures as low as 600 deg C under CO2 gasification conditions 
(negligible hydrogen or water present). It is reasonable to assume 
that the vapour pressure of these metal silicates would have been 
much greater than the base silica or even the base metal species.

One of the downsides of the sintering behaviours was that the silica 
pore structure of the plant material sealed up and trapped carbon 
inside it. The amount of carbon trapped was roughly 1% of the total 
carbon in the feedstock so it is probably not a great concern to most.

The link to my PhD thesis is :

http://adt.library.uq.edu.au/public/adt-QU20060713.095935/index.html

but unfortunately the university seem to restricted the access to all 
digital theses now. So if anyone is really interested I could perhaps 
make a version of the document available via some means. The main PDF 
is about 58 MB by virtue of all the electron microscope images.


regards,

James




>----------------------------------------------------------------------
>
>Message: 1
>Date: Sun, 25 Mar 2007 08:05:42 -0600
>From: Thomas Reed <tombreed at comcast.net>
>Subject: Re: [Gasification] "Continuous analysis of elemental
>         emissions from abiofuel gasifier"
>To: "doug.williams" <Doug.Williams at orcon.net.nz>
>Cc: Gasification at listserv.repp.org, alia Ghandour <ibualia at yahoo.com>
>Message-ID: <460681B6.8040801 at comcast.net>
>Content-Type: text/plain; charset=ISO-8859-15; format=flowed
>
>Dear Tom Miles and all:
>
>We have become increasingly concerned that the ASTM tests for ash fusion
>are particularly inappropriate for biomass gasification.  On your recent
>visit you pointed our that sodium and potassium oxides were quite
>volatile, even at 1000 C, and so might be vaporized during the ash
>fusion test.
>
>In my past life I grew crystals of a wide variety of materials at MIT
>and wrote a book "The Free Energy of Formation of Binary Compounds".  I
>became aware that many oxides do not vaporize congruently, and can
>exhibet a far higher vapor pressure in a reducing atmosphere than in an
>oxidizing atmosphere as in:
>
>       METAL OXIDE + H2 ==> Metal suboxide with higher vapor pressure + H2O
>
>I particularly know this was true for silica.  Quartz workers typically
>find a ring of condensed SiO vapor around the places where they have
>melted quartz in an oxy-hydrogen flame.  I suspect the same is true for
>Na and K oxides.  We are having trouble with slagging of agricultural
>fuels at temperatures below the reported ash fusion temperature.
>
>Comments?
>
>Yours truly,
>
>TOM REED            BEF
>
>
>
>------------------------------
>
>Message: 2
>Date: Sun, 25 Mar 2007 10:30:29 EDT
>From: LINVENT at aol.com
>Subject: Re: [Gasification] "Continuous analysis of elemental
>         emissions from  abiofuel gasifier"
>To: tombreed at comcast.net, Doug.Williams at orcon.net.nz
>Cc: Gasification at listserv.repp.org, ibualia at yahoo.com
>Message-ID: <d4f.53c2ade.3337e185 at aol.com>
>Content-Type: text/plain; charset="US-ASCII"
>
>How about spontaneous eutectification?
>
>
>
>Sincerely,
>Leland T. Taylor
>Leland T."Tom" Taylor
>President
>Thermogenics Inc.
>7100-F 2nd St. NW Albuquerque, NM 87107
>Phone:505-463-8422 Fax:505-268-9206 (call first)
>Web:thermogenics.com
>