Speaker
Description
The H2020 project POLYNSPIRE was launched to improve energy and resource efficiency of post-consumer and post-industrial plastic recycling processes, targeting 100% waste streams. Pillars to reach this ambitious goal are: (1) Chemical recycling to recover plastic monomers and valuable fillers, (2) Advanced additivation to enhance recycled plastics quality, (3) Valorization of plastic waste as carbon source in steel industry, to recover a large amount of mixed plastic discarded from the recycling processes. Plastic is a “new” material for steel sector and can be used to replace fossil coal, reducing virgin raw materials demand, putting steel production in a general frame of circular economy. Its use requires ad-hoc plant components development, in this specific case, new injectors.
Computational Fluid Modelling (CFD) was developed in ANSYS-Fluent frame aimed at simulating new injectors flow behaviour for EAF metallurgical operations. They were designed specifically for plastic injection while maintaining the same metallurgical performance of the standard injectors.
Starting from industrial plant reference conditions, the basic new injectors design, and their performance evaluated in presence of separate injectors for particles and oxygen and operating with a blend of plastic and fossil coal. The possibility of multi-fold injectors for coal and plastic was investigated aimed at achieving the best foaming behaviour. The fluid-dynamic quantities involved at EAF bath level allowed to calculate, by semi-empirical correlations, the penetration of the gas jet and coal particle into slag and steel. Modelling also included simulation of different powder material flow, transport gas flow and secondary boosting air nozzle flow. Moreover, the new feeding systems were simulated both as injectors and burners as flexible in function of the EAF metallurgical operations requested.
The CFD simulations results were assessed with the EAF steelmaking partners, and the performance of new plastic injection systems compared with reference coal case.