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| Author | Topic: Use an extruder for fractionation |
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Dominic Marcotte Member Posts: 2 |
posted August 30, 2001 04:38 PM
   
Has anyone ever used an extruder, single or dual screw, for fractionation. I mean, use this kind of screw to try to extract liquid from a solid. I'm trying to remove water from alfalfa (like grass), this alfalfa get 80% of water, and I could have the possibility to use and extruder in a laboratory. IP: Logged |
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Tom C Moderator Posts: 737 |
posted August 30, 2001 04:49 PM
Lots of things have been done with extruders, but I have not heard of this before. By what mechanism do you propose to remove the water? By compressing the material? Heating it and boiling it off? In a normal extrduer compressing the material will probably squeeze out some of the water but where would it go? There is no exit. Typically much of the energy inputted into the material comes from viscous dissipation. This mecahnism is not available in this case. A fully intermeshing co-rotating twin screw extruder may be a possibility because of some "capture and crush" mechanisms available. Tom @ CCS IP: Logged |
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2beeps Moderator Posts: 111 |
posted August 30, 2001 08:11 PM
Dominic, Most single or twin screw extruders that are vented with a vacuum system can handle 1-2% moisture. But 80%?? Wow!! Perhaps instead of a vacuum system, you set barrel temps in zones 1&2 to 250-300 F TO DISTILL the water through the vent, water being captured and condensed by an ice trap---this still may need a slight vacuum to induce water vapor to exit the vent! Why not give it a try?? Regards, Skip IP: Logged |
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griffex Senior Member Posts: 38 |
posted September 19, 2001 09:00 PM
Dear Dominic Remember you don't need to evaporate the water, except maybe at the very end. That takes energy. Remember also that alfalfa may not like the high temperatures needed to evaporate, or are customary in extruders. I've seen alfalfa dried on a drum dryer, but don't know water content. What you've got here is hay, and there are centuries of good experience in drying hay. There is probably a lot of experience in drying alfalfa, too. If you have a lot of sunlight, dry it in the open air. Talk with agriculture colleges, as well as local farmers in hay-growing areas. Do your "homework" and find out how it's done today. We in extrusion are grateful for your thinking of us, and if you have reasons why traditional approaches are insufficient, come back to us and maybe we can help. Allan Griff Consulting Engineer algriff@griffex.com IP: Logged |
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louis33 Senior Member Posts: 146 |
posted October 10, 2001 02:05 PM
Interesting thought! Whty couldn't you use the extruder as a compression device to squeeze out the water? Drill a few holes in the barrel, and as the materials compress (no heat) it wrings out the water! IP: Logged |
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