Plug screw conveyors became part of the oilseed extraction process around 1920 and have been used for processing soybeans, corn germ, safflower (sunflower), canola (rape seed), peanuts and cottonseed. A typical system includes two types of plug screws:
- Extractor plug screws create a seal that prevents hexane vapors from exiting the extraction system and entering the prep area. They also prevent air ingress in the extractor.
- DT plug screws prevent steam/water vapors from exiting the DT system and entering the extractor or the extractor discharge conveyor. The plug seal also helps to maintain temperature and pressure differences between the DT and extractor.
In the early 1990’s, Conveyor Engineering Co. began working with major oilseed suppliers to more effectively create a barrier for hexane/water vapors, increase power so that plug screws could be started under full load after down time and increase the mechanical integrity of relevant components. Our design has steadily improved and has been successful in 40+ installations. The new design includes: proper length to diameter ratios in order to create a good seal/plug, increased horsepower to move the plug through after upsets, and a shaft seal design with external bearings to ease maintenance and reduce the need to open the system.
We are the leading manufacturer in this category. Our engineers can help you:
- Optimize the balance between power, torque, efficiency and component design limits
- Determine the best materials of construction (304SS, 316SS, Nitrile seals, etc)
- Optimize the plug area length, trough load level and back pressure gate design
- Design to handle difficult products and prevent product co-rotation with the screw
- Increase component reliability for systems that can’t be shut down for weld repair
- With other types of designs (cantilevered screws, etc.)
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