[Gasification] Graphite Heat Exchangers for Producer Gas?

[Tom Miles]

I’m looking at the cold end, cooling from 200C down to 30C where coating has not been a problem. 

 

Tom

 

From: gasification-bounces at lists.bioenergylists.org [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of linvent at aol.com
Sent: Monday, July 16, 2012 3:12 AM
To: gasification at lists.bioenergylists.org
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 <viswanathanks at gmail.com>
To: Discussion of biomass pyrolysis and gasification <gasification at lists.bioenergylists.org>
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 <bobstuart at sasktel.net> 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 <bobstuart at sasktel.net> 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

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