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Götaverken Miljö is developing a new method to reduce emissions of nitrogen oxides (NOx) at waste incineration. The method is applicable to grate furnace systems with staged air supply.
Principle
A jet of water and air is injected into the lower part of the furnace. The jet creates a rotation, resulting in that unreacted oxygen from the char combustion is mixed with unburned components from the volatile combustion (the flames). This brings an extra stage to the combustion, which reduces the NOx-formation.
The injected water reduces the combustion temperature, which also reduces the NOx-formation.
The figure below shows a schematic illustration of the new CUTNOX™ technology.
Pilot tests 
The method was invented by Hans Hunsinger of Karlsruhe Institute of Technology (KIT). Götaverken Miljö has the exclusive right to market the technology. Pilot tests have been carried out at KIT on a 0,5 MW pilot plant for wastes. The tests showed a reduced NOx-content of 70%. The bottom ash quality was also significantly improved.
Read more about the pilot tests here (0,9 MB) 
Full-scale tests
Götaverken Miljö is now testing the method in full-scale and a 30% reduction has been attained. One example of measured results is shown in below figure. Around 5:35 p.m. the water-/air jet is put on. The NOx-content drops from approximately 320 to 225 mg/Nm3. Around 6:35 p.m. the water-/air jet is shut off. The NOx-content then rises again to approximately 320 mg/Nm3.
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