A Global Model for High-Consistency Wood Pulp Suspensions in Corotating Twin Screw Extruders

Researchers at Western University have developed a composite model for the flow of fibrous wood suspensions in working twin screw extruders.

Reference: W-21-006

Background

A twin-screw extruder is a versatile device that is useful for numerous applications due to its modularity and design flexibility. It is a continuous processing device composed of a barrel and a pair of encased customizable screws. In general, twin-screw extruders are mainly used to process polymeric materials, and consequently, a considerable amount of research has gone into the development of performance-predicting simulators to help resolve design and optimization challenges. However, twin screw extruders are also used to process other materials such as fibrous suspensions in the fiber composite, pulp and paper, and oil pressing industries. But, far less research has gone into the design of global models for extruders used in non-polymer processing applications, even though there is a high need for them.

Tech Overview

Researchers at Western University have developed a composite model for the flow of fibrous wood suspensions in working twin screw extruders. The researchers work has benefits over previous models in many ways, with the most prominent benefit being the use of a pressure criterion for solution identification instead of the temperature criterion. Additionally, modifica ons have been made to account for the consistency-dependent rheology of fibrous suspensions as opposed to polymer rheology modeling techniques. Finally, the influence of phase separation and liquid absorption by the biomass in suspension has been considered because both are common occurrences during biomass processing. The model was implemented into a simulator, and the potential of this simulator to predict the axial profiles of major processing variables (i.e., pressure, residence me, filling ratio, liquid and swollen fiber mass flow rate, and consistency) was successfully demonstrated through simulation and experimental comparisons. Although this model was developed for extrusion processing of wood pulp suspensions, it may be easily adapted to other suspension processing applications if the rheological proper es of the suspension can be appropriately modeled. The model was more recently developed into a ready-to-use
software.

Benefits

Ready-to-use software available which offers a high degree of flexibility:

• Facilitates the import of custom screw profile designs using forward conveying, reverse conveying and flightless screw elements through Microsoft Excel
• Correlations for material proper es can be customized for your specific needs
• Generates an interactable graph that may be customized and saved for future reference
• Stores simulation data in an Excel file for more in-depth analyses
• So ware may be tailored to the user’s specific needs through external support

Applications

• Processing pulp suspensions: to predict the axial profiles of major processing variables (i.e., pressure, residence time, filling ratio, liquid and swollen fiber mass flow rate, and consistency).
• Can find use in oil pressing, the food industry, pulp/paper and biofuel creation

Features

• Uses a pressure criterion for solution identification.
• Uses a consistency-dependent rheological model to help predict fibrous suspension flow
• Accounts for phase separation and liquid absorption during extrusion

Opportunity

• Licensing
• Partnerships
• Collaborative Research

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