Design and supply of systems for reducing nitrogen oxides present in the generation of NOx: prompt (formed at low temperature at the start of combustion, insignificant), fuel (by the presence of nitrogen in the fuel) or thermal (to be combined with air at high temperatures).
Catalytics (SCR)
By adding an ammonia/urea solution to the flue gases, NOx can be converted to N2+H2O.
When more restrictive nitrogen oxide emission levels need to be met, it may be necessary to operate in a reactor with a lower-temperature catalyst to increase conversion efficiency.
The reducing agent is injected into the gas stream prior to entering a reactor, where the reduction reaction takes place on a multi-layered bed of porous catalyst at lower temperatures (200-400°C), and reductions of up to 90% can be achieved.
Non-catalytics (SNCR)
This is a more economical solution for NOx removal than catalytic systems, provided that the process temperature is sufficient to complete the reaction between the urea or ammonia and the nitrogen oxides.
They can achieve efficiency levels of up to 60% and include injection and dosing systems for mixtures in the furnace/flue, as well as a control system.
Based on the chemical reduction of the NOx molecule to molecular nitrogen (N2) and water vapor (H2O), urea or ammonia is injected directly into the flue gases at high temperatures in a suitable manner, without the need for a catalyst.
