Experimental investigation of ash behavior and emissions during combustion of Bosnian coal and biomass

This paper presents results of experimental research into the ash behavior of different Bosnian coal types and biomass fired in an electrically heated entrained pulverized fuel flow experimental reactor. The results are derived from a series of tests performed under a range of temperature and air conditions for the fuel test matrix. In essence, the experimental reactor comprises a 3m length alumina–silicate ceramic tube, where combustion takes place, surrounded by SiC stick-type electric heaters and three-layer insulation. The temperature of the reaction zone is controlled by a programmable logic controller (PLC) with thyristor units for each of the heating zones, allowing the process temperature to be varied at will across the range from ambient to 1560 1C. The methodology is based on the evaluation of ash deposits formed in the experimental reactor during the tests. Test points, reflecting the different types of ash deposits, are plotted against appropriate fuel indicators onto graphic diagrams. Emissions of NOx and SO2 are also measured under different ambient conditions—at different temperatures and air distributions—to determine the emission figures for the fuels being tested. The results for six different fuels are presented, namely two single coals, two coal blends, and two coal–biomass blends. The results obtained support the thesis that the appropriate ambient conditions for combustion of coals and biomass can be recognized and recorded in this way.