The combustion of hazelnut shells and bituminous coal was studied in a novel reactor with two disks, supporting two fluidized beds located one above the other. The reactor allows for the study of the impact of the fuels' vertical arrangement in the combustion zone on SO2 emission. The biomass and coal were combusted in separate beds or as a mixture. The gas species concentrations were measured. A major drop in the SO2 coal emission was observed when the coal was combusted underneath the biomass bed, and a minor one, when above.