The phenomenology of bed defluidization during the pyrolysis of a food-packaging plastic waste

The stability, in long-term operation. of fluidized bed reactors utilised t o pyrolyse plastics waste can be seriously compromised by particle agglomer ation phenomena. These phenomena can cause poor fluidization and eventually lead to defluidization. In order to investigate this phenomenon. a polypro pylene waste from a food-packaging industry was utilised in a laboratory-sc ale bubbling fluidized bed reactor. The effect of the main operating variab les (bed hold-up, size of inert material, fluidizing velocity, feed rate of plastic pellets) was investigated by means of experiments carried out unde r an inert atmosphere. The time at which defluidization occurred was correl ated with some process variables by means of linear relationships. A new mo delling approach was also proposed in order to predict the risk of defluidi zation under different operating conditions. (C) 2001 Elsevier Science BN. All rights reserved.