Characterization of pyrolysis products of high-ash excavated-waste and its char gasification reactivity and kinetics under a steam atmosphere

• Published in: Waste management (Elmsford) Vol. 97; pp. 149 - 163
• Main Authors: Zaini, Ilman Nuran, García López, Cristina, Pretz, Thomas, Yang, Weihong, Jönsson, Pär Göran
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.09.2019
• Subjects: Atmosphere; Biomass; Kinetics; Landfill mining; Municipal solid waste; Pyrolysis; RDF; Steam; Steam gasification; Thermogravimetry analysis; Thermogravimetry analysis; RDF; Steam gasification; Municipal solid waste; Landfill mining
• ISSN: 0956-053X; 1879-2456; 1879-2456
• DOI: 10.1016/j.wasman.2019.08.001

•Different fractions of excavated landfill waste were pyrolyzed to produce chars.•The characteristics of the pyrolysis products (gas, oil, and char) were reported.•The chars were tested by using thermogravimetry under a steam atmosphere.•The reactivity and the kinetics parameters of char-steam reaction were determined. The focus of this study is the pyrolysis and gasification of Refuse Derived Fuel (RDF) and fine fractions recovered from the excavation of landfill waste, with an emphasize on the characterization of the reactivity and kinetics of the char-steam gasification. The results from the pyrolysis tests demonstrated that CO and CO2 are the main produced gases during the pyrolysis of the finer fraction of landfill waste. This might be caused by the accumulation of degraded organic materials. The oil products from the pyrolysis of landfill waste were dominated by the derivative products of plastics such as styrene, toluene, and ethylbenzene. The chars obtained from the pyrolysis process were gasified under steam and steam/air atmospheres at temperatures between 800 and 900 °C by using thermogravimetry. The results from the gasification tests demonstrated that the char reactivity was mainly affected by the amount ratio between catalytic elements (K, Ca, Na, Mg, and Fe) over the inhibitor elements (Si, Al, and Cl), as well as the ash amount in the char. The results showed that char from the fine fraction of landfill waste has a higher reactivity than the RDF fraction, due to the high content of catalytic metal elements. These results suggest the use of a smaller sieve opening size for landfill waste separation processes may produce waste fuels with a high reactivity during gasification. Further, based on the thermogravimetric data, the kinetic parameters of landfill waste char gasification were calculated to have activation energies ranging from 54 to 128 kJ/mol.