Extrusion Modeling of Solid Plug Flow of Co-Rotating Twin Screw Pulping Extruder

Abstract

In order to calculate important design parameters, screw axial force and power consumption of twin screw pulping extruder (TSPE), considering actions of the solid material plug in reverse thread of the TSPE and according to static balance principle, an extrusion model including plug flowing and shearing in reverse thread is proposed in the paper. Based on the model, screw axial force, screw torque, power consumption and flow rate can be derived. When changing thread lead numbers or slot width on the flight of the reverse thread, theoretical calculating results and testing results are better consistent.

Estimation on Flux and Power Consumption of Twin Screw Pulping Extruder Based on Dimensional Analysis

“…' c N is the slot number of effective shear of per lead, W c is the width of the slot of reverse thread flight, ψ is the average helix angle of thread, ψ b is helix angle of outer diameter, β ' is the traction angle of reverse shear flow (see Reference [1] for its detailed calculation). At the beginning of design, geometrical parameters of screw H, D b , ' c N , W c , ψ, ψ b and β ' are unknown, Eq.1 cannot be used to calculate flux.…”

“…The estimation results of flux and power consumption of the TSPE are obtained by the Eq.6 and Eq.9 respectively. And the theoretical results of flux and power consumption are based on the extrusion model [1]. Their results and comparison are shown in Table 4.…”

“…In initial design flux and power consumption of the twin screw pulping extruder (TSPE) are estimated according to 2-3 main parameters. References [1] established formulas of flux and power consumption of the TSPE based on the extrusion model. As the formulas deal with nearly all of parameters of the twin screw and material processed, they are not convenient for estimation and initial design.…”

“…Flux is an important parameter indicating the production capacity of TSPE. The flux formula of the TSPE is deduced from extrusion model[1]. It can be expressed as, ' tan 'cos 1 tan ' tan…”

Experiments on Specific Energy and Pulping Quality of Extrusion Mechanical Pulping

“…The core equipment of extrusion mechanical pulping (EMP) is a twin screw pulping extruder (TSPE) References [1][2][3][4][5] show that compared with the disc refiner, specific energy of extrusion pulping (only using the TSPE, not including the subsequent processes) can reduced by 20% to 50%, water about 70%. Therefore, the EMP technology is a kind of pulping technology of environmental protection.…”