[Bioconversion] Re: Algae binder

[Les Blevins]

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
>>
>>
>> _______________________________________________
>> Bioconversion mailing list
>> Bioconversion at listserv.repp.org
>> http://listserv.repp.org/mailman/listinfo/bioconversion
>>
>
>
> _______________________________________________
> Bioconversion mailing list
> Bioconversion at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/bioconversion
>