Optinox - Optimisation of Biomass Firing with the Aim of Reducing Nitrogen Oxide Emissions


Nitrogen oxides (NOx) are harmful gases that are produced during combustion processes. These gases irritate and damage the respiratory organs and contribute in the formation of acid rain, in the reduction of the ozone layer in the stratosphere, as well as affecting the tropospheric ozone and forming smog. It is therefore important to keep their emissions during biomass combustion at a minimum.

Generally, the reduction of nitrogen oxides in combustion processes is done by applying primary and secondary measures. To the primary measures count air and fuel staging while selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are secondary measures to reduce NOx-emissions. Since SCR solutions are usually linked to higher costs due to high equipment expenditures, primary measures (perhaps linked with SNCR) pose a cost-efficient emission reduction method.


The research project focuses on the development of cost-efficient measures to reduce nitrogen oxide emissions from biomass-fired medium-sized combustion plants with a thermal capacity of 1-50 MW. For this purpose, a systematic comparison of different combustion systems (entrained flow, fluidized bed, fixed bed) is carried out and the resulting nitrogen oxide emissions and the distribution between NO and its precursors (HCN, NH3) within the combustion zones are analyzed. The combination of experimental investigations and CFD simulations enables the transferability of the model approach as well as the optimisation of all common biomass furnaces with regard to reduced nitrogen oxide emissions. The aim is to achieve an improved combustion with regard to nitrogen oxide emissions without increasing the emissions of other pollutants (e.g. dust, CO). Air staging, as well as a combination of air staging and SNCR will be investigated.


Fachagentur Nachwachsende Rohstoffe e.V.



  • Chair of Energy Eystems (TUM)
  • Professorship of Regenerative Energy Systems (TUM)


Gabriel Roeder, Sebastian Fendt