Solids Conveying

Andersen, Paul G.; Campbell, Gregory A.

doi:10.3139/9781569908648.004

Cited by 1 publication

(3 citation statements)

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“…When the channels are full, pressure is developed due to the motion of the deforming bed down the channel. The model developed by Campbell and Dontula is used to relate the forwarding angle ϕ to the down channel pressure through a stress balance in the three-coordinate direction [17,31] :…”

Section: Solids Conveying Model Developmentmentioning

confidence: 99%

“…In the 1970s, Burkhardt, [17] Chapter 5, carried out a set of experiments using high-density polyethylene (HDPE). In these experiments, he measured the tip pressure generation.…”

Section: A Commercial-scale Examplementioning

confidence: 99%

“…The four stages of the melting process, which are dominated by heat transfer and dissipative processes, have been identified as follows: (1) partially filled channel pellet flow with heating by conduction, convection, and radiation, (2) compacted pellet flow in the screw channel with heating dominated by friction and conduction, (3) pellet deformation, bulk plastic energy deformation (PED), formation of a liquid phase at the pellet barrel interface, frictional energy dissipation (FED), and (4) fluid flow of the resulting polymer slurry and viscous energy dissipation (VED) as it becomes a homogeneous melt while flowing downstream as shown in Figure 1A. [14][15][16] Figure 1A also shows the melting process for polymer powders (Andersen and Campbell [17] ). The transport and melting of powders and powder/pellet blends experience similar transformations that depend on particle size and other properties.…”

Section: Introductionmentioning

confidence: 99%

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New 2.5‐Dtwin screw extruder model for the feed section of a co‐rotating twin screw extruder with comparisons to data

Campbell

Wetzel²,

Andersen³

et al. 2023

Polymer Engineering & Sci

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Many polymers are processed and compounded in co‐rotating, fully intermeshing twin screw (TS) extruders. The typical compounding process consists of multiple unit operations including feed introduction, conveying solids away from the feed zone, transitioning from the conveying zone to the kneading block (KB) melting zone, melting, a downstream feed zone, a downstream mixing zone, a devolatilization region, and a pressure generating discharge section. This paper will focus on the first of these unit operations, the conveying of pellets in a partially filled screw leading to compaction and pressure generation in the full screw channel prior to the KB melting zone. Mechanisms for pellet conveying, for heating the polymer pellets, and for developing pressure at the end of the solids conveying screw elements are first presented for low‐density polyethylene (LDPE). The predictions of the model are also compared with a classical set of experiments on high‐density polyethylene (HDPE). The model is then tested using published characteristics of a polyamide‐type polymer. This paper focuses on the physics and engineering concepts that are inherent in the feed section of the TS extruder where the pressure is calculated using the friction of the polymer pellets. The effects of throughput, Q, at a constant rotation speed, N, are examined. Low and high Q/N ratios have significantly different axial pressure profiles.

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Section: Solids Conveying Model Developmentmentioning

confidence: 99%

“…In the 1970s, Burkhardt, [17] Chapter 5, carried out a set of experiments using high-density polyethylene (HDPE). In these experiments, he measured the tip pressure generation.…”

Section: A Commercial-scale Examplementioning

confidence: 99%