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.
Various compositions of refuse derived fuel (RDF), and the differences in its thermal degradation behavior, make the modeling, design, and operation of thermal conversion systems a challenge. In this paper, the pyrolysis characteristics of RDF in a pilot-scale unit were investigated to determine the operating conditions for a 30 kg/h scale pyrolysis melting incinerator. The gaseous volatile and tar components in the pyrolysis products were measured using gas chromatography (GC). The morphology of the char derived from RDF pyrolysis was observed using scanning electron microscopy (SEM). The Arrhenius parameters and prediction of the pyrolysis time were obtained from isothermal kinetic results. The results of the kinetic analysis indicated that the firstorder reaction model was reliable for predicting the conversion of RDF pyrolysis. A reasonable thermal decomposition scheme of RDF pyrolysis has also been discussed.
A considerable variation exists in the kinetics constants that were derived using Arrhenius equation in the study of the reaction kinetics for wood pyrolysis. It is of interest to evaluate whether compensation behaviours that usually associate with a series of related reactions might have contributed to the observed variations in the nonisothermal pyrolysis kinetics. The study of the compensation effects was intended to seek a logical explanation for the observed variations of the apparently large and differed values of activation energy and pre-exponential factors. Statistical regression analyses were performed to correlate the Arrhenius parameters derived from the non-isothermal Thermogravimetry Analysis (TGA) data. To gain an insight on the competing reactions so as to expound the varied kinetic data, these transition kinetics were also analyzed for exothermic transition using Differential Scanning Calorimetry (DSC) for heat of pyrolysis. This study showed that compensation effect existed, but found that the enthalpy of transition held a stronger proposition on the transition kinetics. KEYWORDS
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