Modeling and process simulation of waste macadamia nutshell pyrolysis using Aspen Plus software

Abstract

The production of biofuel from any biomass waste like waste macadamia nutshell (WMNS) using pyrolysis has recently gained enormous attention as it can address both issues related to environmental pollution and fuel crisis. However, pyrolysis experiments are time consuming and costly. Therefore, this study aimed to develop a process model for WMNS pyrolysis process using Aspen Plus software to analyze the complicated pyrolysis reactive system and obtain valuable insights into how to optimize pyrolysis operating conditions. In this study, WMNS was pyrolyzed at 500 °C and its products yield, namely bio-oil, biochar, and syngas, was measured. The bio-oil was then analyzed for its elemental composition. The experimental conditions were recreated in ASPEN Plus model and validated against experimental results. A high degree of agreement was found between the simulation and experimental results. To study the effect of various parameters on pyrolysis products yield as well as the composition of bio-oil, many simulation runs were carried out at different moisture contents of WMNS, pyrolysis operating temperatures, and WMNS particle sizes. It was found that amongst these parameters, pyrolysis operating temperature played the most significant role in determining the yields of pyrolysis products and bio-oil composition. It can be concluded that the developed model is capable of predicting pyrolysis products yield and bio-oil composition for any biomass waste.