[Gasification] Graphite Heat Exchangers for Producer Gas?

[linvent at aol.com]

Dear Tom,
     That is where I had to come up with other than a fixed surface heat 
exchanger configuration. Higher temperature is not as much of a 
problem. As to filtration, I have never seen a carbon filter and only 
suspect why it is not used is the cost in comparison to say paper. For 
diffusion systems, cost was no object, but they have been replaced with 
centrifuges.

Sincerely,
Leland T. "Tom" Taylor
Thermogenics Inc. 


-----Original Message-----
From: Tom Miles <tmiles at trmiles.com>
To: 'Discussion of biomass pyrolysis and gasification' 
<gasification at lists.bioenergylists.org>
Sent: Mon, Jul 16, 2012 7:35 am
Subject: Re: [Gasification] Graphite Heat Exchangers for Producer Gas?

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  
ksvOn 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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