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Advisor(s)
Abstract(s)
Gasification of wastes is considered a promising alternative for
energy generation due to its lower environmental impacts when compared with
conventional landfilling and incineration. Valorisation of such wastes improves
sustainability of resource management and of energy production. However, an
appropriate characterisation of wastes in terms of physical and chemical properties
is essential for the prediction of their behaviour during gasification,
allowing to identify possible problems for the environment and installed
equipment and also to define which materials present a greater energy potential.
This study aimed to characterise 10 different fractions from municipal, construction
and demolition wastes received in different fluxes by a Portuguese
waste management company. These fractions included wood (44.83 wt%),
plastic (22.15 wt%), paper/card (0.04 wt%), mixtures of paper and plastic (14.67
wt%) and sewage sludge (18.31 wt%). For this purpose, determination of
density, proximate and ultimate analysis, higher heating value (HHV), thermogravimetric
profiles and inorganic composition of ashes were performed for
each fraction. Analysis revealed that plastics and their mixtures with paper/card
possess the highest HHV’s (25–45 MJ/kg db), thus exhibiting a greater capacity
for energy production. High levels of ashes found in dried sewage sludge (50 wt
% db) indicate that a lot of by-product will be generated after gasification,
possibly increasing the treatment costs. A gasification unit operating at 50 kg/h
and admitting a mixture of all these wastes would generate 109.7 kW of total
power, having capacity to receive more waste fluxes along the year.
Description
Keywords
Municipal solid waste Construction and demolition waste Property analysis Gasification