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 Extrusion, Single Screw
 direct injection of butane into extruder
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| Author | Topic: direct injection of butane into extruder |
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NORSHELL Member Posts: 2 |
posted July 23, 2007 11:28 PM
  
please replay if you know about the process of injecting butane gas into a single screw extruder for making of foam food containers from gpps crystals and some eps regrind. IP: Logged |
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Tom C Moderator Posts: 881 |
posted July 24, 2007 09:50 AM
I have no expertise in this area, but I believe this requires 2 extruders, 1 for melting and 1 for cooling, to do this work. I that the set up you have or are considering? ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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Stephen J. Derezinski Senior Member Posts: 76 |
posted July 27, 2007 09:35 PM
Perhaps a two-stage screw in a single extruder could do the job? You design the normal extraction section with a pumping section able to withstand pressure for dissolving the butane instead of a vacuum for extracting vapor. So called "infusion screw." ------------------ IP: Logged |
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NORSHELL Member Posts: 2 |
posted July 28, 2007 09:34 PM
what company designs "infution screws" for single screw extruders in canada? IP: Logged |
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Stephen J. Derezinski Senior Member Posts: 76 |
posted July 29, 2007 12:46 AM
Infusion Screw: Any good screw designer with the proper analytical tools or models should be able to design this device easily. You just need to size the pumping section (second stage) to hold back the gas pressure that you need to "infuse" the melt with the gas. Also, the first stage must be designed to develop that same infusion gas pressure. Therefore, channel depths in first and second stages will be not so deep. You will loose flow rate in exchange for the ability to infuse the gas. ------------------ IP: Logged |
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Tom C Moderator Posts: 881 |
posted July 29, 2007 09:35 AM
Steve, By my understanding certain polymers require a second "cooling" extruder so that the melt viscosity is high enough when it foams at the exit. I don't know what dividing lines there are between resins, viscosity, blowing agent, extrudate form and so on that determines whether it can be done on a single or tandem extruder. Any insight? ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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Stephen J. Derezinski Senior Member Posts: 76 |
posted August 03, 2007 08:32 PM
Tom-- The second stage could be designed to cool instead of heat to some degree. But, as you say, the details of the required conditions will dictate if that is possible (at aome resonable production rate.) Intuitively, a deepened second stage with a shortened lead length might do the trick. Deep to lower viscous heating, and short lead to still provide the flow rate at the pressure gradient desired (high psi in the extruder, low psi at the exit.) IP: Logged |
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Bob Cunningham Senior Member Posts: 126 |
posted August 03, 2007 09:18 PM
What is the reason you can't use a secondary extruder like most foam processes? What about a dual-diameter screw? Offhand, I doubt you can get a screw long enough for good cooling with the blowing agent. IP: Logged |
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