Kinetic Study in Modeling Pyrolysis of Refuse Plastic Fuel

Abstract

For the pyrolysis of refuse plastic fuel (RPF), the typical particle size is large and the time required for pyrolysis is long. Therefore, the rate-limiting mechanisms of gas diffusion and chemical reaction might be important. In this paper, the kinetics of RPF pyrolysis was investigated through a thermogravimetry analysis under isothermal conditions between 300 and 600 °C. A kinetic model was used to examine the effects of the surface chemical reaction and gas diffusion on the rate-limiting steps of RPF pyrolysis. The results show that the rate was controlled by a combination of the surface chemical reaction and gas diffusion through the solid product layer. The activation energies for the surface chemical reaction and gas diffusion were determined to be 70.2 and 65.9 kJ mol-1, respectively. The weight loss of RPF pyrolysis occurred mainly at temperatures higher than 400 °C and increased with temperatures. Concentrations of pyrolysis gases including H2, CO, and hydrocarbons were analyzed through a real-time gas analyzer. Gas yields from pyrolysis were sensitive to temperatures higher than 300 °C, while a very small amount of gas was released at 300 °C.