Study of the pyrolysis of municipal solid waste for the production of valuable products

• Published in: Journal of analytical and applied pyrolysis 2011, Vol.92 (2), p.366-375
• Main Authors: Velghe, I., Carleer, R., Yperman, J., Schreurs, S.
• Format: Article
• Language: English
• Subjects: fuels; gas chromatography-mass spectrometry; gases; heat; Heavy metals; hydrocarbons; metals; Municipal solid waste; nitrogen; Oil; oils; Pyrolysis; streams; thermogravimetry; Wax
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2011.07.011

To obtain information on the potential of thermal conversion (pyrolysis) of municipal solid waste (MSW), a thermogravimetric study (TGA) is performed in a stream of nitrogen. Based on TGA results, pyrolysis experiments are carried out in a semi-batch reactor under inert nitrogen atmosphere. Slow pyrolysis is performed up to 550 °C (heating rate of 4 °C/min). Fast pyrolysis is performed at 450, 480, 510 and 550 °C and different input transfer rates (12 or 24 g material/min). The pyrolysis products are studied on composition and yield/distribution and investigated for their use as valuable product. The liquid obtained by slow pyrolysis separates spontaneously in a water rich product and an oily product. For all fast pyrolysis conditions, a viscous, brown oil which contains a poly(ethylene-co-propylene) wax is obtained. Composition analyses by GC/MS of the oil products (slow/fast pyrolysis) show that aliphatic hydrocarbons are the major compounds. The pyrolysis oils have high calorific value (between 35 and 44 MJ/kg), low wt% of water (around 6 wt%) and a low O/C value (between 0.2 and 0.3). The presence of waxy material is probably due to incomplete breakdown of poly(ethylene-co-propylene) present in MSW under study. The optimal pyrolysis conditions, regarding to oil yield, fuel properties, and wax yield is fast pyrolysis at 510 °C with 24 g material/min input transfer rate. The fast pyrolysis gases contain mainly hydrocarbons and have an averaged LHV around 20 MJ/Nm 3. ICP-AES analyses of pyrolysis products reveal that almost none of the metals present in MSW are distributed within the liquid fractions.