An investigation on thermal recycling of recycled plastic resin (numerical prediction of unburnt rate in PET-resin powder combustion)

Abstract

To burn PET-resin powder as an alternative fuel and to realize the effective thermal recycling of a great deal of recycled PET resin, a series of experimental investigations has been made on the physical aspect of PET-powder combustion in the industrial burner, The results showed that a large amount of PET-powder of up to about 80% is exhausted without burn-up in the open atmospheric operation, whereas it is perfectly consumed in the high temperature in-furnace operation. Understanding of the relationship between the heating time and the unburnt rate of PET-powder is therefore necessary for getting an important knowledge to reduce the amount of unburnt PET-powder. In this paper, the behavior of particle diameter is first modeled according to those experimentally measured, a particle-size histogram of PET-powder is transformed to a particle-number distribution by stepping the particle diameter at 0.01 μm intervals, and finally a numerical prediction of the unburnt rate in the PET-powder combustion is attempted by introducing the parcel approximation. The results give good quantitative agreement between the unburnt rates of PET-powder measured experimentally and those predicted numerically.