De-NOX SNCR

The SNCR treatment of nitrous oxides takes place through a reaction with ammonia, activated by high temperature (850-1050°C). These temperatures are generally reached immediately downstream of an incineration or calcining furnace.

 

The ammonia can be injected into an aqueous solution (around 25%) or through the decomposition of a diluted urea solution. The use of urea generally involves fewer safety restrictions during transit and storage.

 

The first stage in the creation of an efficient SNCR system is the definition of the thermal profile of the area in which the reaction is to take place.

 

Area Impianti can draw on many years of experience in the field, and has the expertise to analyse, through a series of measurements, the thermal profile of the plant; by taking account of the geometry of the system, the company can plan out the positioning of an appropriate number of injection points.

The injection process is carried out using specific nozzles in which the reagent solution is sprayed with compressed air. The nozzles are then flushed and cooled with air. 

 

The system allows users to measure out the correct quantity of reagent through a feedback algorithm with analysis of the emissions, which also makes it possible to keep the ammonia slip (unreacted ammonia) below the limit levels.

By means of a hydraulic cabinet and a control unit, the plant automatically deals with the management of the different fluids and optimises the reactivity based on the temperatures.

 

The fact that this SNCR system is installed upstream of an SCR system is particularly interesting.