[Bioconversion] Densification Realities...

[Thomas Reed]

Dear All:

Les has focused on some of the realities of densification.  Biomass 
comes in a million forms, most of which could be fuels - if densified 
and pelletized (or made into logs or briquettes).  Currently only a few 
are economic.  Be careful to define your sources, aims and needs.

TOM REED      BEF    RHF

Les Blevins wrote:

> Len, Neal et al:
>
> Len I believe you are correct in saying the friction created as solid 
> material is forced by the screw to pass through an extruder will tend 
> to heat the material being extruded and the water contained in the 
> material (if heated enough) will cause the material to essentially 
> cook and then explode, (or rather puff up), upon emerging from the 
> pressure inside the extruder as it emerges into the atmosphere.
>
> However having worked with extruders producing pet food from 
> ingredients such as flour; I am highly skeptical as to the feasibility 
> of using extruders on more dense biomass forms such as algae, sawdust 
> and certainly anything like wood shavings or straw with larger 
> particle sizes would plug-up an extruder even if very well wetted. I 
> would think dried to wet algae and liquids would probably fall 
> somewhere like dried to wet sawdust and/or wood shavings and liquids 
> on an extruder plugging-potential basis. I doubt algae, sawdust, or 
> other biomass forms would explode or even swell up like products that 
> contain flour which we all know will expand and 'raise' up with yeast, 
> moisture or warming or heating as in cooking because that puffing or 
> raising comes mostly from the yeast. When extruding pet foods (Tender 
> Chunks) the extruders had steam heating of the barrel to keep the 
> ingredients hot enough to cook in the few seconds it took to pass 
> through the extruder as the heat from friction alone wouldn't be 
> sufficient.
>
> Len you said "I have done it" so I would like to hear more about that. 
> Tell us more about what you were using for feedstock and what the 
> product being extruded was.
>
> I believe there is a big difference in the physics and mechanics of 
> extrusion and that of pellet mills and briquetting machines.
>
> I can well remember a plugged extruder meant an hour or so opening the 
> barrel to expose the screw so it could be cleaned of the packed 
> material and then replacing the shear-pins and then starting up again 
> from scratch. Speaking from experience I would say anyone 
> contemplating putting biomass in forms more dense than flour and 
> liquids in an extruder would be well advised to buy plenty of shear-pins.
>
> Les Blevins
> AAEC
>
>
> ----- Original Message ----- From: "Len Walde" <sigma at ix.netcom.com>
> To: <CAVM at aol.com>; <bioconversion at listserv.repp.org>
> Sent: Thursday, December 29, 2005 7:39 AM
> Subject: Re: [Bioconversion] Re: Algae binder
>
>
>> Neal et al:
>>
>> I  am confident you can extrude sawdust and similar biomass.  The 
>> critical element in the process is the moisture content.  Friction 
>> heat can/will cause the too-wet biomass to create enough steam to 
>> cause the extrusion to "explode" upon exiting the die. Find the right 
>> moisture and/or control the heat,  it will work. I have done it.
>>
>> Keep me in the loop on your experiments.
>>
>> Happy New Year!
>>
>> Len Walde
>>
>>               Sigma Energy Engineering, Inc.
>> Creative Problem Solving & Process Engineering
>> Serving Agriculture, Mining, Industry & Commerce
>>             through "Symbiotic Recycling" tm
>>                        Est. 1985
>>
>>      Ph:  925-254-7633
>>      E-mail: sigma at ix.netcom.com
>>
>>
>> ----- Original Message ----- From: <CAVM at aol.com>
>> To: <bioconversion at listserv.repp.org>
>> Sent: Wednesday, December 28, 2005 7:25 PM
>> Subject: [Bioconversion] Re: Algae binder
>>
>>
>>> Les Blevins wrote:
>>>
>>> I've had  experience with extruders and dies here at the Lawrence 
>>> dog food
>>> plant  which was a Quaker Oats facility back then, and we made 
>>> thousands and
>>> thousands of tons of little balls each week that were called Tender 
>>> Chunks
>>> (smile) and they were made mostly of such things as flour, meat and 
>>> bone
>>> meal and animal fat among other things.
>>>
>>> These ingredients were  cooked in the extruders under heat and 
>>> pressure and
>>> came out of the dies  as soft balls that were about the same size as 
>>> cheese
>>> puffs, and they  firmed up somewhat as they cooled. Heat and 
>>> pressure is what
>>> made them  bind together once the proper balance between solid and 
>>> liquid
>>> ingredients  was obtained.
>>> ------------------------------------------------------------------------------ 
>>>
>>> -------------------------------------------
>>> I have an InstaPro 600 extruder and an oil press at my plant in 
>>> southern
>>> Indiana.  If either of these are useful in producing a binder 
>>> quality from algae
>>> I am willing to give the process a try.
>>>
>>> Hmm, I wonder if I can extrude wood with this machine...
>>>
>>> Neal
>>>
>>>
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>>
>>
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-- 
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