Solids Conveying Devices at Clarkson University

Two solids conveying devices were built at the Clarkson Polymer Extrusion Consortium. The first device was used to visualize the flow in the section without a discharge pressure. The second device was built such that a relatively high discharge pressure could be applied to the process. 

The barrel floats on the screw, rather than being permanently affixed to the frame of the device itself. This facillitates the measurements of barrel torques and thrusts as a function of operating conditions and the type of polymer being conveyed. Fig. 5.9 schematically details the extruder section of the solids conveying device and the instrumentation location [10]. Dark red arrows indicate force measurements, and light yellow rectangles represent temperature and heat flux measurements. A total of five force devices allowed the measurement of the screw 

Commercially available heat flux sensors with thermopiles sandwiched at the interface were used to measure the local temperatures and heat fluxes that is. Omega Corporation, Model HFS-4 devices. The total thickness of the sensors was nominally less then 0.18 mm, and a schematic of the device is shown in Fig. 5.10. By measuring the temperature difference across the center film (AT) and assuming one-dimentional heat transfer, then the heat flux can be measured using the temperature difference and the thermal conductivity of the film. The local temperature is recorded using the thermocouple nearest the barrel. The senors were calibrated at ambient condition with zero heat flux. 

In order to see if the system could provide the flexibility to evaluate high modulus polymer pellets, an initial comparison of an HDPE and PS resins were evaluated. The experiments were conducted at a screw speed of 50 rpm and barrel temperatures of 24 and 35 °C for the HDPE and PS resins, respectively. The temperature of the screw was maintained at the barrel temperature. These conditions are similar to what might be observed in the feed casing and very early into Section 2. As 

The goal of this preliminary investigation was to gain more knowledge of the Interaction between solid polymer physical properties and their relation to extruder rate and energy dissipation characteristics In the solids conveying zone. The data presented here will focus on the effects of temperature and polymer type on solids 

---