[Gasification] Retort gasses

Tue Jan 30 21:45:40 CST 2007

Jonathon,

> The figures given in the FAO source seem erroneous to me.  Other sources 
> put
> the retort gas output at virtually no N2 and much lower CO2 levels.

Could you please post these other sources?  I'm glad to get all the retort 
gas references I can.  They'll be good info for the archives, too.

>but a setup similar in which the gas passes through the hotest
> layers of char formed.  I would love to know more about your own retort 
> with
> higher efficiency.

Again, go look at my retort article.  The gas vents from the bottom of the 
retort tank into the afterburner pipes inside the firebox.  The burners are 
aimed back up at the outer tank bottom.   All retort off-gas passes through 
the hottest char layer on the retort bottom adjacent to the firebox fire. 
FYI, the maximum UPPER stack temperature recorded so far was 1158 F.  During 
operation parts of the firebox sides glow cherry red.  Since the sides are 
sheet steel that indicates outer firebox temps of 1500F - 1600F.

> Besides the "Vertical Column - bottom heated" style retort<

This one is heated on the bottom and 360 around the sides up to the top.

>Instead of one straight tube, perhapps a base
> that is designed a little different (for the glowing char zone) to yield
> better results in the output gas.

I still think the CO - H2 ratio will be poor for methanol synthesis compared 
to a downdraft gasifier's output.   And the gas will have a much higher 
heavy tarry volatiles content.

Mark

> Message: 3
> Date: Mon, 29 Jan 2007 07:43:48 -0500
> From: "Jonathan F. Pratt" <jonpratt76 at hotmail.com>
> Subject: Re: [Gasification] Retort gasses
> To: <gasification at listserv.repp.org>
> Message-ID: <BAY101-DAV15EB94C6902C6EA15F7907C6A70 at phx.gbl>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> The figures given in the FAO source seem erroneous to me.  Other sources 
> put
> the retort gas output at virtually no N2 and much lower CO2 levels.  FAO
> itself mentioned that the gas output is affected by the scrubbing process
> (water) in which other gasses may be "picked up" by the raw gas passing
> through.  So there are variables in the type of retort and filtration
> process.  FAO also said the energy content of the retort gasses is only 
> 10%
> that of the charcoal produced?  That can't be right as 2/3 of the energy 
> is
> contained in the volitile gasses given off.
>
> As for the Riche specifically, I wasn't advocating using the Riche design
> exactly but a setup similar in which the gas passes through the hotest
> layers of char formed.  I would love to know more about your own retort 
> with
> higher efficiency.
>
> Besides the "Vertical Column - bottom heated" style retort itself one can
> imagine using one or more additional chambers filled with charcoal and
> heated glowing hot to better breakdown the tar and reduce the CO2 resident
> in the raw pyrolysis gasses.  Instead of one straight tube, perhapps a 
> base
> that is designed a little different (for the glowing char zone) to yield
> better results in the output gas.
>
>> ------------------------------
>>
>> Message: 4
>> Date: Mon, 29 Jan 2007 00:47:30 -0500
>> From: "Mark & Elena Gallmeier" <mgallmeir at comcast.net>
>> Subject: Re: [Gasification] Why is nitrogen dilution bad?
>> To: <gasification at listserv.repp.org>
>> Message-ID: <022a01c74368$f7ba4cf0$6402a8c0 at c9y1p2>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> reply-type=original
>>
>> Jonathon,
>>
>>>> The retort will produce a gas free of nitrogen and will mainly be a mix
>>>> of
>>>> methane, H2 and CO and a bunch of other hydrocarbons in small
>>>> percentages.
>>
>> According to http://www.woodgas.com/gasification.htm:
>>
>> "Producer Gas" made with air:       (CO 22%; H2 18%; CH4 3%, CO2 6% and 
>> N2
>> 51%).
>> "Synthesis Gas" made with O2:    (CO 40%,  H2 40%, CH4 3% and CO2 17%)
>>
>> Meanwhile the UN FAO gives the following analysis for "Retort Gas":
>>
>> "Retort Gas"  (CO 23%, H2 2%, CH4 17%, CO2 38%, O2 2%, N2 18%)
>>
>> See
>> http://www.fao.org/docrep/X5555E/x5555e07.htm#6.10%20using%20retort%20or%20converter%20gas
>>
>> The problem with retort gas is the hydrogen deficiency for the methanol
>> synthesis reaction:  CO + 2H2 ---> CH3OH.
>>
>> Using straight retort gas I doubt one would improve on the 'natural'
>> methanol yield of 2% from destructive distillation.  The hydrogen balance
>> needs improving by some means, whether Steam Methane Reformation, water
>> gas
>> shift or both.  A regular gasifier will yield a better balanced CO-H2 gas
>> and be easier to build.
>>
>>>>The Riche style retort is essentially a long
>>>> vertical tube heated from the bottom,
>>
>> This retort I built accomplishes everything a Riche gas producer does, 
>> but
>> without the firebrick masonry flue of the stock Riche, and with far less
>> fuel consumption:
>>
>> http://gasifiers.bioenergylists.org/?q=gallmeierretort
>>
>>>>the gasses generated in the retort
>>>> pass through the glowing char formed at the bottom and to some extent
>>>> breaktown the tars and other constituents in the raw pyrolysis gas.
>>
>> Even the higher temperatures obtainable in a retort won't do much tar
>> cracking.
>>
>> Mark
>>
>
>
>
>
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