The main goal of this research project is to investigate the potential and benefits of the fuel-staged and reburning technologies for reduction of highly-hazardous NOx emissions when burning biomass with elevated fuel-N (as main fuel) in a fluidized-bed combustion system at maximum possible fuel conversion into energy.
The objectives pursued in this research project are as follows:
1. to modify the fluidized-bed combustor for the co-firing two (primary and secondary/reburning) biomass fuels using the fuel-staged and reburning combustion methods;
2. to perform four experimental test series on the combustor for: (i) conventional fluidized-bed combustion of individual (primary/secondary/reburning) biomass fuels, (ii) co-combustion of the pre-mixed fuels using conventional air supply (iii) co-combustion of the fuels using fuel staging (i.e., injection of these fuels into the combustor at different levels) and conventional (bottom) air supply, and (iv) co-combustion of the fuels using reburning technology (integrating fuel staging and air staging);
3. to investigate the effects of (i) the combustion method, (ii) fuel properties (e.g., moisture, fuel-N, and volatile matter of both fuels) and (iii) operating conditions (excess air, proportion of primary and secondary/reburning fuel, and air staging when reburning) on formation and oxidation/reduction of major gaseous pollutants (CO, CxHy, and NO) in distinct reactor regions, as well as on the emissions and combustion efficiency of the biomass-fueled combustor;
4. to quantify and compare the NO reduction efficiency between the fuel-staged and reburning combustion methods for specified ranges of operating conditions;
5. to investigate the distribution of heat flux along the combustion height and compare this characteristic between different combustion methods and operating conditions;
6. to provide recommendations on the optimal operating parameters ensuring the highest combustion efficiency of the combustor and maximum NO emission reduction when using the fuel-staged and reburning technologies;
7. to provide a state-of-the-art on recent and ongoing achievements in developing/improvement of the NO emission reduction technologies.