[Gasification] Retort construction, hydrogen embrittlement, and similarity in appearance between the motorcycle gasifer and the gasifier Peter is working with.

Wed Jan 31 18:15:13 CST 2007

Dear Ken

Hydrogen embrittlement of steel sheet at 450 C should not be a problem.

Hydrogen embrittlement shows up at low temperatures, and leads to "shatter 
cracking." It was a huge problem with railroad rails in Northern Canada, but 
the Metallurgist at the local Steel Plant developed a process for removing 
hydrogen from steel about 1935. Basically, they built "Mackie Tanks", and 
simply allowed the rails to cool slowly, so that hydrogen had a chance to 
diffuse out of the rails. No more hydrogen embrittlement or shatter cracking 
of rails treated with the Mackie Process.

Best wishes,

Kevin
----- Original Message ----- 
From: "drew" <drew at artforging.com>
To: "Ken Basterfield" <ken at basterfield.com>
Cc: <gasification at listserv.repp.org>
Sent: Wednesday, January 31, 2007 7:02 PM
Subject: Re: [Gasification] Retort construction, hydrogen embrittlement, and 
similarity in appearance between the motorcycle gasifer and the gasifier 
Peter is working with.

> Very interesting Ken,
>
> http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-46RCS9Y-1G&_user=10&_coverDate=01%2F31%2F2003&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9b3e1d6362dbeead676347ead7cc4f75
> <http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TJJ-46RCS9Y-1G&_user=10&_coverDate=01%2F31%2F2003&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9b3e1d6362dbeead676347ead7cc4f75>
> Secondary recrystallization behavior of the grain-oriented silicon steel
> utilizing MnSe, AlN and Sb as inhibitors was investigated through the
> observation of the specimens secondary recrystallized partially during
> the final annealing. The atmosphere of higher hydrogen content
> accelerated primary grain growth and enhanced {1 1 1} and {1 1 0}
> texture in the surface region at the early stage of the final annealing.
> Consequently, iron loss was reduced due to smaller grains after
> secondary recrystallization. The best value of the material of 0.23 mm
> thickness without domain refining was 0.82 W/kg as /W/_17/50 and 1.95 T
> as /B/_8 . The fact that hysteresis loss was reduced as well as eddy
> current loss, makes it evident that many secondary grains having sharp
> {1 1 0}left angle bracket0 0 1right-pointing angle bracket texture
> developed under the atmosphere of high hydrogen content.
>
> This seems like a description of what you saw, and why they used the
> process.    The steel sheet stock you talk about would likely never be
> subject to mechanical stress, high temperature, or corrosion, so I would
> think my earlier post still relevant.
>
> All the best
> Drew
>
>
> Ken Basterfield wrote:
>> Drew,
>> As  an apprentice, I remember we had steel strip annealing firnaces that
>> used hydrogen for the annealing atmosphere.
>> The steel had slightly raised silicon content for use in motor and
>> transformer laminations. I don't recall any embrittlement problems.
>> Ken
>>
>>
>> I've stopped 1,050 spam and fraud messages. You can too!
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>>
>>
>> -----Original Message-----
>> From: gasification-bounces at listserv.repp.org
>> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of drew
>> Sent: 31 January 2007 20:38
>> To: snkm at btl.net; gasification at listserv.repp.org
>> Subject: [Gasification] Retort construction, hydrogen embrittlement, and
>> similarity in appearance between the motorcycle gasifer and the gasifier
>> Peter is working with.
>>
>>
>> Hi Peter and List
>>
>>     An issue that has been problematic for me in working with retorts is
>> that of hydrogen embrittlement in steel.    Especially in thin steel
>> sheets it has been problematic.    When you have hot steel (red hot is
>> hot enough) and a low oxygen high hydrogen gas present the hydrogen can
>> migrate into the steel (the low oxy environment conspires to remove the
>> iron oxides which might have reduced the hydrogen penetration), where
>> apparently it bonds with the carbon present to create methane at many
>> times the constituents original volume.   This leads to cracking and
>> rapid corrosion (in steel corrosion rates are directly related to both
>> temperature, and strain so the combination of heat, and the tension
>> caused by the methane is double trouble).    I suspect that this will
>> give any steel retort that passes 450F for extended periods a short
>> life.   Most stainless steels are corrosion resistant only because of
>> the thin layer of oxides formed on the surface, these oxides are quickly
>> stripped of their oxygen in high temp low oxy environments and rapid
>> corrosion takes place even at low temperatures.     The use of a easily
>> removable, and easily replaceable reduction tube in imbert gasifiers
>> shows a good strategy for dealing with this type of corrosion, once a
>> system was proved perhaps a ceramic tube could take it's place?   With
>> retorts the large surface area needed to transfer the heat and the
>> expansion/contraction of that large surface area seem to make that path
>> a difficult one, perhaps John F.  would comment on his strategy for
>> dealing with this in his continuous retort system?   Systems like his
>> would seem to be a great match with micro charcoal gasifiers allowing a
>> larger scale controllable process.to do the dirty side of the process
>> (extraction of hydrocarbons), with the clean relatively pure char used
>> in small gasification plants or returned to the soil as an amendment.
>>     I wonder if anyone notice the similarity in appearance between the
>> WWII era motorcycle gasifier pics I posted to the Chinese gasifier Peter
>> has been testing?    I mistakenly called it a charcoal gasifier, but
>> after rereading the article realize the author clearly states it is
>> running very well on beach wood scraps.
>>
>> http://en.wikipedia.org/wiki/Decarburization
>>
>> http://en.wikipedia.org/wiki/Hydrogen_embrittlement
>>
>> All the Best
>> Drew
>>
>>
>
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