Self-energized pyrolysis process for sustainable biochar production from biowastes

In an increasingly sustainable world, the new industrial processes are more and more focused on recirculating the waste to upgrade their value. Therefore, the aim of this thesis is to give new life to different kinds of biowaste. To do so, pyrolysis has been implemented. A preliminary literature review has been conducted to identify which are the optimal operating conditions, the reactor configuration that better fits for the present purpose and, if any research has been conducted on this field. The self-energized pyrolysis process has not been investigated a lot, on the other hand the literature on pyrolysis is vast. The three main products of this process are biochar (solid phase), vapors (gaseous phase) and bio-oil (liquid phase). All the experiments have been held in absence of oxygen and with different operating conditions, in order to evaluate the best result in terms of energy content of the vapor phase and biochar production. The present research has focused mainly on using the gas and vapors to self-energize the process itself, burning them. The solid phase, biochar, can instead be used in many external applications such as soil remediation, carbon sequestration or additive in organic solid waste composting. The main issue related to pyrolysis process is the high energetic consumption to keep the high temperature constant within the reactor, but the studies done for this work show that a self-sustaining process is feasible, under certain conditions. To develop this scope, a sketch of the design for the self-energized pyrolysis process is proposed. The proposed system is beneficial to maintain the temperature required for pyrolysis. The importance of maintaining high levels of efficiency in the pyrolysis process has been discussed, especially during the drying stage and within the pyrolysis chamber. The study shows that even small variations in efficiencies can drive the system to a point of unsustainability, highlighting the need for accurate design and operation.