Improving the efficiency and robustness of a microwave polystyrene pyrolysis reactor through combined experiments and simulations

Plastics are widely used and their end-of-life management remains a challenge. In 2016, Canadians disposed 3.3 million tons of plastics where 86% was landfilled, 4% was incinerated with energy recovery and only 9% was recycled. The low recycling rate is partly due to a limited market for the recycled material produced via mechanical technologies like optical sorting, washing, drying, and extrusion that we find in current recycling plants. Generally, such mechanical technologies do not enable a closed loop approach where the recycled material would be reintroduced into virgin-like applications.

Pyrowave’s microwave depolymerization technology has received increasing attention in recent years due to the advantages associated with microwave heating. The heating mechanism in this approach significantly enhances monomer yields compared to conventional technologies. In conventional methods, heating occurs based on conduction/convection, while with microwave, the energy is transferred on a volumetric basis. Polystyrene does not considerably interact with microwave fields. As such, a dielectric material particles are introduced in the system to convert the microwave energy into heat that promotes the polymer depolymerization at high temperature. Microwave irradiation selectively heats the dielectric material, which prevents secondary undesired reactions. Pyrowave’s reactor is a stirred-tank reactor, which is recognized as a suitable unit operation for non-Newtonian fluids like melted polystyrene. There are still multiple opportunities for optimization of Pyrowave’s reactor. The shape of the agitator can be optimized to promote the suspension of solid particles, maximise fluid circulation and prevent the risk of arcing. This is the goal of this project.

Faculty Supervisor:

Bruno Blais

Student:

Partner:

Pyrowave

Discipline:

Engineering

Sector:

Manufacturing

University:

Polytechnique Montréal

Program: