Primary Formation of PCDD/F in a Circulating Fluidized Bed Boiler Co-Firing Waste with a "Clean" Biomass - Impacts of Fuel Quality
Paper in proceedings, 2012

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 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 the fuel quality was studied in the 12 MWth circulation fluidized bed (CFB) boiler located at Chalmers University of Technology by comparing the concentrations of PCDD/Fs found in the raw gas after the convection pass of the boiler and the PCDD/Fs found in the fly ashes. Sorted, crushed and pre-dried waste pellets from IcoPower in the Netherlands were compared to a clean biomass case consisting of only stem wood in the form of a mixture of wood chips. PCDD/Fs were also found in the fly ashes which may be a problem in the future during ash disposal. The formation of PCDD/Fs was significantly reduced in the raw gas after the convection pass as well as in the fly ashes during co-combustion of waste pellets with municipal sewage sludge compared to the case where the waste pellets were used without the addition of the sludge. A link is demonstrated between the level of alkali chlorides in the gas phase, the chlorine content in the deposits in the convection pass and the formation of PCDD/Fs.

Combustion of biomass

PCDF

Alkali chlorides

Dioxins

Sewage sludge

PCDD

Author

Lars-Erik Åmand

Chalmers, Energy and Environment, Energy Technology

Johannes Öhlin

Chalmers, Energy and Environment

Jessica Malene Bohwalli

Chalmers, Energy and Environment

Dongmei Zhao

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Yanguo Zhang

Proceedings of the 21st International Conference on Fluidized Bed Combustion

Driving Forces

Sustainable development

Subject Categories

Materials Engineering

Chemical Engineering

Chemical Sciences

Areas of Advance

Energy

More information

Created

10/7/2017