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.

High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor

“…The reaction is unlikely to be controlled by the gas-film mass transfer; therefore, the rate controlling steps should be the chemical reaction or the product layer diffusion, or both. For the surface chemical reaction, the rate of the CO 2 capture is defined as [18,26,27]:…”

“…A model of the reaction core allows for a change in the radius of the particle to be given by [26]: r 3…”

“…When ı 2 > 10, it is safely assumed that it is under the control of product layer diffusion. An intermediate value of ı 2 suggests that the CO 2 capture at high temperature is controlled by the chemical reaction and the product layer diffusion [18,24,[26][27][28].…”

Study on pyrolysis characteristics of refuse plastic fuel using lab-scale tube furnace and thermogravimetric analysis reactor

“…Due to the increase of the amount of plastics in MSW, RPF has been considered as a viable renewable energy source because of its high heating value [2]. RPF contains 60-70% waste plastics, which consists of 5% low-density poly ethylene (LDPE), 20-25% poly vinyl chloride (PVC), 30-35% polystyrene (PS), and 5% polypropylene (PP) [3].…”

“…Dou et al [2] studied kinetics of RPF pyrolysis through a TGA under isothermal conditions between 300 • C and 600 • C. The kinetic model was used to examine the effects of the surface chemical reaction and gas diffusion on the rate-limiting steps of RPF pyrolysis. Lee et al [10] studied the characteristics of pyrolysis and steam gasification of RPF for the production of hydrogen-rich fuel gas at high temperatures (700-1000 • C).…”