I’m looking at the cold end, cooling from 200C down to 30C where coating has not been a problem.
Tom From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, July 16, 2012 3:12 AM To: [email protected] Subject: Re: [Gasification] Graphite Heat Exchangers for Producer Gas? Not worth messing with in my opinion. 1. Any fixed surface will still coat, even at very low tar content. 2. At high temperature, C+CO, C+H2 reactions will eat up graphite, 3. if resin coated, will not handle temperature and solvents in the gas. Sincerely, Leland T. "Tom" Taylor Thermogenics Inc. -----Original Message----- From: Viswanathan KS <[email protected]> To: Discussion of biomass pyrolysis and gasification <[email protected]> Sent: Sun, Jul 15, 2012 10:12 pm Subject: Re: [Gasification] Graphite Heat Exchangers for Producer Gas? Process for producing graphite tubes: Quote Synthetic graphite is manufactured from crude oil cokes and pitch. The pasty mixture is shaped into monolithic blocks or tubes. Tubes are extruded whereas blocks are usually vibration molded. The shape is then carbonized at 900ºC (1650 F)for a few hours and then fully graphitised at 2900ºC (5250 F) for several days. The block or tubes are then impregnated with synthetic resin that is then polymerized to render them totally impervious to gases and fluids. The resulting material is fully corrosion resistant to most common acids (sulfuric acid, hydrochloric acid and of course industrial phosphoric acid) and has a very high thermal conductivity of around 80 W/m.K for tubes or 140 W/m.K for blocks when totally graphitised. The tube wall is quite thick, 6 mm (1/4”) and the individual tubes are 3 meters (10’) long. Unquote ksv On Mon, Jul 16, 2012 at 9:27 AM, Bob Stuart <[email protected]> wrote: In the early days of graphite fiber/graphite matrix brake disks on race cars, the ceramic coating would sometimes crack, allowing oxygen onto the hot graphite. The result became known in the pits as "Designer Coal." Bob On 15-Jul-12, at 9:50 PM, Viswanathan KS wrote: IMO the graphite tubes are not coated. On Mon, Jul 16, 2012 at 8:45 AM, Bob Stuart <[email protected]> wrote: Would the coating that protects the graphite from oxidation not also work on copper? Bob On 15-Jul-12, at 8:10 PM, Tom Miles wrote: Graphite heat exchangers are now used on domestic condensing hot water boilers. (See SGL Group.) Heat transfer is reportedly 8 times that of stainless steel. Why not use them for cooling and condensing producer gas? Tom _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
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