The thermal decomposition of a Solid Recovered Fuel (SRF) has been studied by two techniques. First, laboratory-scale experiments were performed in a horizontal furnace in which different atmospheres are studied to analyze the dioxins and furans (PCDD/Fs) evolved from the decomposition of the material. Sulfur presence is revealed to be important in PCDD/Fs formation. In the second technique, the emission of various pollutants (PAHs, PCDD/Fs, metals, acid gases …) were determined in a cement kiln fed on different proportions of SRF material, and where a maximum feed rate of 15000 kg SRF/h was achieved. In the laboratory furnace the dioxin toxicity revealed a maximum when the amount of oxygen in the atmosphere increased until approximately stoichiometric conditions. In the cement kiln, all emitted pollutants are under the legal limits. No correlation between SRF input and metal emission was observed.
Ultrasound technology was proved as an efficient processing technique to obtain micro-molded specimens of polylactide (PLA) and polybutylene succinate (PBS), which were selected as examples of biodegradable polyesters widely employed in commodity and specialty applications. Operational parameters such as amplitude, molding force and processing time were successfully optimized to prepare samples with a decrease in the number average molecular weight lower than 6%. Ultrasonic waves also seemed an ideal energy source to provide effective disaggregation of clay silicate layers, and therefore exfoliated nanocomposites. X-ray diffraction patterns of nanocomposites prepared by direct micro-molding of PLA or PBS powder mixtures with natural montmorillonite or different organo-modified clays showed the disappearance of the 001 silicate reflection for specimens having up to 6 wt.% clay content. All electron micrographs revealed relatively homogeneous dispersion and sheet nanostructures oriented in the direction of the melt flow. Incorporation of clay particles during processing had practically no influence on PLA characteristics but enhanced PBS degradation when an organo-modifier was employed. This was in agreement with thermal stability data deduced from thermogravimetric analysis. Cold crystallization experiments directly performed on micro-molded PLA specimens pointed to a complex influence of clay particles reflected by the increase or decrease of the overall non-isothermal crystallization rate when compared to the neat polymer. In all cases, the addition of clay led to a clear decrease in the Avrami exponent.
The present work has been carried out to verify the feasibility of thermal valorization of an 10 automobile shredder residue (ASR). With this aim, the thermal decomposition of this waste has 11 been studied in a laboratory scale reactor, analyzing the pollutants emitted under different 12 operating conditions. The emission factors of carbon oxides, light hydrocarbons, PAHs, PCPhs, 13 PCBzs, PBPhs, PCDD/Fs, dioxin-like PCBs and PBDD/Fs were determined at two temperatures, 600 14 and 850ºC, and under different oxygen ratios ranging from 0 (pure pyrolysis) to 1.5 (over-15 stoichiometric oxidation). After analyzing all these compounds, we conclude that thermal 16 valorization of ASR is a clean way to treat this waste. 17
The thermal decomposition of a Solid Recovered Fuel (SRF) has been studied using thermogravimetry, in order to get information about the main steps in the decomposition of such material. The study comprises two different atmospheres: inert and oxidative. The kinetics of decomposition is determined at three different heating rates using the same kinetic constants and model for both atmospheres at all the heating rates simultaneously. A good correlation of the TG data is obtained using three n th order parallel reactions.
The pyrolysis and combustion of automotive shredder residue (ASR) were studied by dynamic thermogravimetry and derivative thermogravimetry (TG-DTG) at heating rates of 5, 15 and 30 K min -1 at atmospheric pressure. For the simulation of pyrolysis and combustion processes two different kinetic models are proposed. One of them is based on the distribution of activation energies (DAEM), with three pools of reactants (three pseudocomponents) because of the complexity of the samples studied. The other model assumes a simple first-order decomposition of the three different fractions. The experimental thermogravimetric data of pyrolysis (oxygen absence) and combustion (at two different oxygen concentrations) processes were simultaneously fitted to determine a single set of kinetic parameters able to describe both processes at the different heating rates. The comparison of the models permits to discuss the importance to consider a distribution of activation energies. The experimental results and kinetic parameters may provide useful data for the design of thermal decomposition processing system using ASR as feedstock.
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