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Conversion of microwave pyrolysed ASR's char using high temperature agents
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.ORCID iD: 0000-0002-1837-5439
2011 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 185, no 1, 472-481 p.Article in journal (Refereed) Published
Abstract [en]

Pyrolysis enables to recover metals and organic feedstock from waste conglomerates such as: automotive shredder residue (ASR). ASR as well as its pyrolysis solid products, is a morphologically and chemically varied mixture, containing mineral materials, including hazardous heavy metals. The aim of the work is to generate fundamental knowledge on the conversion of the organic residues of the solid products after ASR's microwave pyrolysis, treated at various temperatures and with two different types of gasifying agent: pure steam or 3% (v/v) of oxygen. The research is conducted using a lab-scale, plug-flow gasifier, with an integrated scale for analysing mass loss changes over time of experiment, serving as macro TG at 950, 850 and 760 degrees C. The reaction rate of char decomposition was investigated, based on carbon conversion during gasification and pyrolysis stage. It was found in both fractions that char conversion rate decreases with the rise of external gas temperature, regardless of the gasifying agent. No significant differences between the reaction rates undergoing with steam and oxygen for char decomposition has been observed. This abnormal char behaviour might have been caused by the inhibiting effects of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating.

Place, publisher, year, edition, pages
2011. Vol. 185, no 1, 472-481 p.
Keyword [en]
ASR char, Microwave pyrolysis, High temperature agent gasification, Pyrolysis rate, Gasification rate
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-33712DOI: 10.1016/j.jhazmat.2010.09.056ISI: 000289446700064ScopusID: 2-s2.0-78649332755OAI: diva2:418242
QC 20110520Available from: 2011-05-20 Created: 2011-05-16 Last updated: 2011-06-07Bibliographically approved
In thesis
1. Conversion of biomass and waste using highly preheated agents for materials and energy recovery
Open this publication in new window or tab >>Conversion of biomass and waste using highly preheated agents for materials and energy recovery
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

One of the greatest challenges of human today is to provide the continuous and sustainable energy supply to the worldwide society. This shall be done while minimizing all the negative consequences of the operation(s) to the environment and its living habitants including human beings, taking from the whole life cycle perspective. In this thesis work new solutions for treatment biomass and waste are analyzed.


Based on the fundamental research on the conversion of various materials (biomass: straw pellets, wood pellets; and waste: plastic waste, ASR residues after pyrolysis), converted by means of different systems (pyrolysis in a fluidized bed reactor, gasification in a fixed-bed reactor using highly preheated agents) it is recommended to classify materials against their charring properties under pyrolysis, in order to find the best destination for a given type of fuel. 


Based on phenomenological research it was found that one of the important effects, affecting performance of downdraft gasifiers, is the pressure drop through the bed and grate. It affects, directly, the velocity profile, temperature distribution and of the height of the bed, especially for the grate with restricted passage surface, although it was not investigated in literature. The lower grate porosity, the higher conversion of fuel and heating value of gas is produced. However, the stability of the process is disturbed; therefore reducing the grate porosity below 20% is not recommended, unless the system is designed to overtake the consequences of the rising pressure inside the reactor. This work proposed the method for prediction of a total pressure drop through the fixed-bed downdraft gasifier equipped with a grate of certain porosity with an uncertainty of prediction ±7.10.  


Three systems have been proposed; one for the treatment of automotive shredder residue (ASR), one for the treatment of plastic waste (polyolefins) and one for biomass (wood/straw pellets). Pyrolysis is an attractive mean of conversion of non-charring materials (like plastic waste) into valuable hydrocarbons feedstock. It gives directly 15-30% gaseous olefins while the residue consisting of naphtha-like feedstock has to be reformed/upgraded to olefins or other chemicals (e.g. gasoline generation) using available petrochemical technologies. Pyrolysis of complex waste mixture such as ASR is an attractive waste pretreatment method before applying any further treatments, whereby useful products are generated (gaseous and liquid fuel) and char, rich in precious metals. The solid residues are meant for further treatment for energy and metals recovery. Gasification is a complementary method for handling pyrolysis residues. However, metals can be removed before gasification. Pyrolysis of charring materials, like biomass, is a very important step in thermo-chemical conversion. However, the char being approximately 25%wt. contains still very high caloric value of about 30MJ/kg. This in connection with the High Temperature Steam Gasification process is a very promising technology for biomass treatment, especially, above 900oC. This enhances the heat transfer towards the sample and accelerates kinetics of the gasification. This, in turn, improves the conversion of carbon to gas, increases the yield of the producer gas and reduces tar content. At higher steam to fuel ratio the process increases the yield of hydrogen, making it suitable for second-generation biofuels synthesis, whereas at lower steam to fuel ratio (S/F<2) the generated gas is of high calorific value making it suitable for power generation in a combined cycle.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 115 p.
biomass, waste, pyrolysis, gasification, ASR
National Category
Metallurgy and Metallic Materials
Research subject
SRA - Energy
urn:nbn:se:kth:diva-34253 (URN)ISBN 978-91-7501-033-5 (ISBN)
Public defence
2011-06-15, D3 (entreplan), Lindstedtsvägen 5, KTH, Stockholm, 10:00 (English)
QC 20110607Available from: 2011-06-07 Created: 2011-05-30 Last updated: 2011-12-12Bibliographically approved

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