Kinetics of Scrap Tire Pyrolysis in a Conical Spouted Bed Reactor

Abstract

The kinetics of the pyrolysis of tire material has been studied in a conical spouted bed reactor (CSBR), in the range between 450 and 600 °C, for two particle size ranges (between 0.1 and 0.8 mm and between 0.8 and 4.0 mm). The kinetic results have been compared with those obtained for the same material with other technologies, namely, thermogravimetry and a fast heating microreactor. This comparison and the one carried out with the literature results for similar materials have permitted the analysis of the effect of the technology and of the experimental conditions of pyrolysis (especially particle size) on the kinetic results. It has been proven that the CSBR is especially suitable for the kinetic study of these materials, as it allows for obtaining an excellent gas-solid contact, which minimizes the limitations of heat and mass transfer and maintains bed isothermallity at high temperatures, within the temperature ranges and heating rates of interest for scaling-up. In the pyrolysis of small particles (between 0.1 and 0.8 mm), the apparent activation energy is 121.3 kJ mol -1 and the corresponding frequency factor is 1.0 × 10 6 s -1 . The effect of particle size is significant and shows the impossibility of totally avoiding the limitations of heat and mass transfer in the pyrolysis of these materials.

An algorithm for the kinetics of tire pyrolysis under different heating rates

“…Also, apparent characteristic times and activation energies for thermal lag peaks elucidated from these models do not necessarily correspond to 'real' activation energies for any single reaction. The heat and mass transfer consideration is also independent of any reactor geometry, and additional considerations would be required for specific reactor geometries [29,30].…”

Product distribution modelling in the thermal pyrolysis of high density polyethylene

“…2, with the aim of obtaining flash pyrolysis data under conditions similar to industrial units. This reactor is especially suitable for flash pyrolysis [8][9][10][11][12], given that the gas residence time is very short. Runs have been carried out in the 450-715 • C range.…”

Kinetic study of polyethylene terephthalate (PET) pyrolysis in a spouted bed reactor

“…This good performance is a consequence of the solid flow pattern and the action of the spout which avoids the formation of agglomerates. Spouted beds have been applied successfully for the kinetic studies of pyrolysis of a number of polymers including waste tires [16,17], polystyrene [18], polyethylene and polypropylene [13,19,20], poly-(methyl methacrylate) [21]. Nevertheless, the kinetic modeling of PET has not yet been considered in spouted bed reactors.…”

“…In previous kinetics studies using spouted beds, the weight change of the samples has been determined by suction of the bed content by means of a suction pump and weighing the mass [17]. In this study, weight change of PET samples has been monitored continuously during the pyrolysis reaction as a novel technique.…”