Upgrading of refuse derived fuel through torrefaction: Evaluation of RDF char fuel properties

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Non-hazardous industrial waste (IW) is a source of refuse-derived fuels (RDF). RDF production is considered a priority solution regarding waste management in industrialized countries. It allows significant reductions on the amount of end-of-life materials sent to landfills and it enhances energy recovery from different wastes. Nevertheless, the heterogeneous nature of RDF, its moisture and chlorine contents can limit their use in energy applications because of low combustion efficiency and generation of toxic emissions. Moreover, the polymeric fraction of RDF can create problems of agglomeration in feeding systems and char accumulation in fluidized beds. Torrefaction has the potential to improve the physical, chemical and energy characteristics of this raw material, contributing to its homogenization, increasing its density, hydrophobic character and gross calorific value while significantly reducing its volume. This thermal conversion process promotes water volatilization and the elimination of different functional groups from the surface of the raw material, leading to permanent changes in its composition, namely a decrease in the O/C ratio and an increase in hydrophobic character. This work intended to study the torrefaction of RDF at different conditions of temperature and residence time and the characteristics of the obtained chars. Torrefaction caused a reduction in mass and volume of the RDF but also resulted in an increase of density and high heating value (HHV). Ash and fixed carbon contents also increased for most torrefaction conditions. RDF char produced at 300 ºC for 30 minutes yielded the best compromise between proximate analysis parameters, with 9.4 and 22.3 % wt for ash content and fixed carbon, respectively. The same RDF char showed a volume reduction of 44% when compared to the raw RDF and an increase in density of 33%. These results show that effectively, the torrefaction process can be applied to RDF in order to enhance fuel and material properties, but torrefaction conditions should be carefully chosen for each initial RDF composition in order to maximize upgrading while keeping energy and operating costs to a minimum.

Original languageEnglish
Title of host publicationECOS 2018 - Proceedings of the 31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems
PublisherUMDGEO - Department of Geography of University of Minho
ISBN (Electronic)9789729959646
Publication statusPublished - 2018
Event31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2018 - Guimaraes, Portugal
Duration: 17 Jun 201821 Jun 2018

Conference

Conference31st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2018
CountryPortugal
CityGuimaraes
Period17/06/1821/06/18

Keywords

  • Ash
  • Char
  • Leaching behavior
  • RDF
  • Torrefaction

Fingerprint Dive into the research topics of 'Upgrading of refuse derived fuel through torrefaction: Evaluation of RDF char fuel properties'. Together they form a unique fingerprint.

Cite this