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 or additional fuel and to realize effective thermal recycling of a great deal of wasted and recycled PET-resin, some practical studies have been made on the physical aspects of PET-powder combustion in the industrial burner. The results showed that a large amount of PET-powder up to about 80 % is exhausted without burn-up in the open atmospheric operation, whereas PET-powder 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 to get 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 then transformed into a particle-number profile by stepping the particle diameter at 0.01 µm intervals, and simple numerical prediction of the unburnt rate in the PET-powder combustion is finally attempted by introducing the parcel approximation. The results give good quantitative agreement between the unburnt rates of PET-powder measured experimentally and those predicted.