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Modelling of Pyrolysis of Wastes

  • Supervisor: Raffaella Ocone, Heriot Watt University
  • Sponsoring Company: Nextek
  • PhD Student: Haoyu Li

Pyrolysis is a process increasingly employed for thermochemical conversion of wastes and recovery of lower molecular weight hydrocarbon products to be used as fuel or chemical feedstock. The optimisation of the process demands knowledge and control of the kinetics of pyrolysis for accurate predictions of the products’ distribution.

The lumping kinetics approach (e.g., Astarita, G and R Ocone, AIChE Journal, 34, 129, 1988) is applied to model the pyrolysis of wastes and successive fractionation of the liquid products. The schematic of the process is as follows:


 

A discrete lumping methodology is applied to the three lumps formed by the gases, the oil and the char resulting from the pyrolysis of wastes. The fractionation of the oil is described through the continuum lumping approach. The “lump” represented by the oil, obtained through the application of the discrete lumping (DL) model represents the feedstock for the continuum lumping (CL) model to furnish the composition of the fractioned products. The work presents a number of scientific challenges: firstly, the kinetics of plastics pyrolysis must be elucidated; additionally, the fractionation of the bio-oil would present an “apparent” kinetics of the multi-component mixture which is not simply explicable through the kinetics of each single reaction.