Experimental study on biomass advanced reburning for nitrogen oxides reduction

Advanced reburning (AR) is effective for nitrogen oxides (NOx) reduction, which integrates the basic reburning (BR) with the injection of nitrogen agents and additive compounds. The basic reburning of poplar, cornstalk, wheat-straw and peanut shell, is studied on a boiler simulator facility (BSF). The influence of operating parameters and the synergistic effect of the injection of ammonia, urea or/and sodium carbonate on NOx reduction are investigated. The results show that an efficiency of 54–67% NOx reduction could be achieved during the basic reburning process under the optimum operating conditions and the efficiency would be increased if nitrogen agent is injected with the over-fire air or into the burnout zone. Further, co-injection of sodium carbonate with the nitrogen agent could make the NOx reduction process more thorough. On the whole, 85–92% NOx reduction could be achieved during the advanced reburning process with a reburning fuel heat input of 15–20%.

Research highlights▶ The herbaceous biomass, such as cornstalk and wheat-straw, is abundant in north China and has being used as single or co-firing fuel in some small power plants. ▶ If biomass could be used as the reburning fuel for NOx reduction in the conventional coal-fired boilers, more environmental benefits will be achieved. ▶ The primary object of this study is to evaluate the performance of different biomass during BR and AR process, and optimize the parameters to get a better condition for NOx reduction.