Decreased PCDD/F formation when co-firing a waste fuel and biomass in a CFB boiler by addition of sulphates or municipal sewage sludge
Artikel i vetenskaplig tidskrift, 2013

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are formed during waste incineration and in waste-to-energy boilers. Incomplete combustion, too short residence times at low combustion temperatures (<700 C), incineration of electronic waste and plastic waste containing chlorine are all factors influencing the formation of PCDD/Fs in boilers. The impact of chlorine and catalysing metals (such as copper and iron) in the fuel on PCDD/F formation was studied in a 12 MWth circulating fluidised bed (CFB) boiler. The PCDD/F concentrations in the raw gas after the convection pass of the boiler and in the fly ashes were compared. The fuel types were a so-called clean biomass with low content of chlorine, biomass with enhanced content of chlorine from supply of PVC, and solid recovered fuel (SRF) which is a waste fuel containing higher concentrations of both chlorine, and catalysing metals. The PCDD/F formation increased for the biomass with enhanced chlorine content and it was significantly reduced in the raw gas as well as in the fly ashes by injection of ammonium sulphate. A link, the alkali chloride track, is demonstrated between the level of alkali chlorides in the gas phase, the chlorine content in the deposits in the convection pass and finally the PCDD/F formation. The formation of PCDD/Fs was also significantly reduced during co-combustion of SRF with municipal sewage sludge (MSS) compared to when SRF was fired without MSS as additional fuel.

Dioxins

Co-combustion

Municipal sewage sludge

Ammonium sulphate

PCDD/Fs

Alkali chlorides

Författare

Lars-Erik Åmand

Chalmers, Energi och miljö, Energiteknik

Håkan Kassman

Vattenfall Research and Development AB

Waste Management

0956-053X (ISSN)

Vol. 33 8 1729-1739

Drivkrafter

Hållbar utveckling

Ämneskategorier

Energiteknik

Annan naturresursteknik

Styrkeområden

Energi

Infrastruktur

Chalmers kraftcentral

DOI

10.1016/j.wasman.2013.03.022

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Senast uppdaterat

2018-09-06