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Pyrolysis and combustion of waste lubricant oil were studied due to its important potential value as a fuel. A thermogravimetric analysis in nitrogen atmosphere conditions and with different proportions of nitrogen:oxygen (N 2 , N 2 :O 2 mixtures at 4:1 and 9:1 ratios), different weights (1, 2.5 and 5 mg) and different heating rates (5, 10 and 15 °C min −1 ) were carried out to study the thermal decomposition. Both pyrolysis and combustion can be represented in two processes: in the first process, a volatilization of the oil takes place (this depends on the initial mass and the heating rate) and in the second process there is a decomposition, which is a different process in combustion from the process in pyrolysis. The identification of the volatile and semivolatile compounds from pyrolysis and combustion of used diesel oil was carried out in a tubular reactor at 500 and 850 °C. On the one hand, the semivolatile PAH compounds (naphthalene, phenanthrene, anthracene, etc.) were detected as much in pyrolysis as in combustion (850 °C), but the most highly carcinogenic is benzo(a)pyrene which was only found in pyrolysis at 850 °C. On the other hand, the levels of PCDD/Fs and dioxin-like PCBs were estimated after a fuel-rich combustion process at around 113 pg WHO-TEQ g −1 burnt oil (corresponding to 80 pg I-TEQ g −1 ) and 3 pg WHO-TEQ g −1 burnt oil, respectively. The PCDD/Fs concentration in the raw sample was estimated at around 7–16 pg WHO-TEQ g −1 used oil (or 6–13 pg I-TEQ g −1 ) and PCBs were not detected. |
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