During the production of cement, harmful nitrogen oxides (NOx) can be emitted into the air, depending on the different process variables used. NOx is detrimental to both human health and the environment because once it is emitted into the air it can become a component of smog and acid rain. These can cause pulmonary and respiratory issues, as well as destroying vegetation and plant growth.
In order to control NOx at cement plants, selective non-catalytic reduction SNCR systems are used. For the non-catalytic reaction, a reagent (mostly aqueous ammonia) is specifically injected in the area of the optimum temperature window of approx. 950 - 1.050°C . Exceeding or falling below the temperature window will lead to additional NOx formation or an increase in the NH3 slip. The efficiency is reduced in both cases. In addition to the optimum temperature, parameters such as droplet size and velocity are also of crucial importance. Only with the appropriate nozzle and the right control concept can the droplets penetrate deep enough into the flue gas flow to ensure optimum distribution of the reducing agent in the flue gas flow.