The impact of zeolites during co-combustion of municipal sewage sludge with alkali and chlorine rich fuels
Paper in proceeding, 2009

Municipal sewage sludge has proven to eliminate alkali metals and chlorine related problems during combustion of straw and refuse derived fuels (RDF). However, the mechanisms involved have not been clarified. The aim of this work was to gain more knowledge about the behaviour of sewage sludge and detergent zeolites in combustion and about their effects on alkali metal chemistry. Co-combustion tests with combinations of municipal sewage sludge, wood and straw were carried out in a 12 MW fluidised bed (FB) boiler. In addition, a detergent zeolite, Doucil A24, was used as additive during co-combustion of wood and straw. The chemical characteristics of fuels and fly ashes were studied using several methods, such as chemical fractionation and scanning electron microscopy with element analysis by energy dispersive fluorescence detection (SEM-EDX) and X-ray diffraction (XRD). In the co-combustion tests involving sewage sludge no KCl was found in the flue gas prior to the convection pass. The zeolite addition was less effective but the KCl concentration was reduced to some degree in favour of HCl compared to the reference case. Both SEM-EDX and XRD confirmed the presence of potassium-aluminium-silicates in the fly ash fraction in all cases. In addition, the laboratory study showed that Doucil A24 had the ability to capture potassium and KCl at temperatures in the range of 700-900°C.




fly ash



Anita Pettersson

Chalmers, Energy and Environment

Anna-Lena Elled

Chalmers, Energy and Environment

AnnaBell Möller


Britt-Marie Steenari

Chalmers, Chemical and Biological Engineering, Industrial Materials Recycling

Lars-Erik Åmand

Chalmers, Energy and Environment

Proceedings of the 20th International Conference on Fluidized Bed Combustion in Xi:an, China May 18-20, 2009

Vol. 2 903-909
978-7-302-20146-5 (ISBN)

Driving Forces

Sustainable development

Subject Categories

Energy Engineering

Other Environmental Engineering

Areas of Advance



Chalmers Power Central





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