Biomass is an important source of energy and heat production. Nitrogen oxides can be emitted through combustion, which can cause environmental and health issues. The nitrogen content of biomass varies extremely depending on the source, with primary sources such as wood usually containing low nitrogen contents while waste streams have higher nitrogen content, leading to higher NOx production. This study investigates the NOx emissions from two pulverized fuels with different characteristics, namely torrefied wood and dry digestate, as well as nitrogen content and the potential of NOx reduction through air staging. The former fuel is selected as a usual high-caloric biomass fuel and the latter as the source from a waste stream. The experiments were conducted in an entrained flow combustion reactor, which allows for a decoupling of the combustion parameters (temperature, stoichiometric ratio). The effect of the combustion temperature was only pronounced for the dry digestate combustion. Air staging reduced the NOx emissions from both fuels by up to 80% at higher combustion temperatures. However, since the digestate displayed higher NOx emissions, the final NOx levels did not reach below 200 mg/Nm3 at 6% O2. Therefore, it is important to investigate the NOx emissions from different fuels, especially with higher nitrogen content, and the reduction potential from primary NOx reduction measures, as these are usually the most cost-effective methods.     «

Biomass is an important source of energy and heat production. Nitrogen oxides can be emitted through combustion, which can cause environmental and health issues. The nitrogen content of biomass varies extremely depending on the source, with primary sources such as wood usually containing low nitrogen contents while waste streams have higher nitrogen content, leading to higher NOx production. This study investigates the NOx emissions from two pulverized fuels with different characteristics, namel...     »