One dimensional simulation of extrusion channel of biomass pelleting machine

U.P Onochie,O.O Ighodaro,K.O Otomi,C.C Kwasi-Effah

doi:10.4314/jasem.v22i8.11

Abstract

This study was carried out to simulate the extrusion channel of a biomass pelleting machine. The numerical model developed by Nielsen was used. In order to obtain a simulation of the pelleting process, a number of assumptions for the material properties were made. These include Poisson’s ratio (υ = 0.02), Young modulus (E = 20) and Friction coefficient (μ = 0.4). Other variables (dimensions) used for the pelleting channel in the model are the active press length (l =70mm), diameter of pellets (50mm), inlet angle (30o) and chamfer depth (z = 2mm). MATLAB was used for the simulation analysis. Based on the sensitivity analysis, it was observed that the pressure increases at the inlet, which is mainly caused by the decreasing cross sectional area of the elements. The density also increases at the inlet, until it reaches its final value between the inlet and the cylindrical channel. An offset of the accumulated energy was observed at the start of pellet channel which is caused by the amount of energy used for compressing the pelleting material to the density. The peak pressure is found at the interface between the inlet section and the cylindrical channel. The maximum pressure in the die decreases when the inlet depth increases and also, the pressure gradients in the inlet increases, when the inlet angle increases. The highest pressure is 35MPa for compatibility of the pellets thereby increasing its durability.Keywords: Pressure, Density, Energy consumption, Pelletizer

Highlights

The pelleting process is an energy consuming process
The force variation required for pelleting as well as the variation of the pressure and density in the pelleting channel are presented in Figures 4 and 5 respectively
It is observed that the variation causes the pressure to increase at the inlet, which is mainly caused by the decreasing cross sectional area of the elements

Summary

Introduction

The pelleting process is an energy consuming process. it is essential to evaluate the production methods, and search for ways to optimize the design of the pellet mills (Nielsen, 2009). Nielsen (2016) reported that the development of the pelleting process has until now mostly been focusing on the material that is pelleted, rather than evaluate the physical design of the pelleting machine and developed a model for simulating the pelleting channel. This research adopts the model reported in Nielsen (2016) which was used for the simulation of the extrusion channel of a pelleting machine. The Nielsen model is set up to simulate the pelleting process in the axial direction of the pelleting channel. A radial force in the pelleting material, acting normal to the die wall, appears as a consequence of the axial acting force. The relation between the axial strain and the force applied in the axial direction, , is expressed in equation (6)

Methods

Results

Conclusion