Reducing NOx with SNCR and SCR systems using Urea reagent

Urea is an important raw material for the chemical industry. It is widely used in NOx control systems to reduce nitrogen oxides emissions. Yara is a leading urea producer and has been supplying Urea to its customers for many years, including for use to reduce NOx emissions.

• With SNCR systems, urea is often the reducing agent chosen for safety reasons. However, it is less effective than ammonia, because urea needs to be converted to ammonia before the NOx reduction process.

• We supply either solid urea, typically for on-site dilution, or urea in solution with several concentrations.

Why choose Urea as your reagent?

  • Poses fewer risks in the workplace and doesn’t require specific training, unlike ammonia.
  • Is non-hazardous being stable, non-volatile, non-explosive and non-flammable.
  • Can be safely transported, stored and handled without the need for specific training.

There are disadvantages of using Urea as a reagent in NOx control

  • Urea can lead to additional nitrous oxide or carbon monoxide emissions (poisonous gases).
  • It is less effective than Ammonia.
  • There is an increased probability of fouling and corrosion in equipment downstream of the injection point.
  • Leakages of Urea solution lead to white salt precipitates giving an ageing look to your equipment.
  • Scaling and clogging may occur when blended with hard water for DeNOx operation.
  • Urea solutions must be provided with sufficient heat to avoid freezing. The freezing point depends on the concentration, with 40% starting to freeze at 0°C.


 Urea / Urea Solution can be transported by :

  • Truck (solid packed) / Silo Truck (bulk)
  • Container (solid packed and bulk)
  • Railcar (solid packed and bulk)
  • Vessel / Barge (solid packed and bulk)

Anti-chipping solution

Troubleshoot chipping issues related to the use of urea as a reducing agent in SNCR systems

Some urea SNCR systems require the addition of water to dilute the urea before injection. If urea is used with hard water, it can cause chipping problems, or even plugging the injection nozzles, which stops the operation of the system.

Yara has developed an anti-chipping NOxCare solution to eliminate problems on NOx control SNCR systems.


Why choose Yara to supply Urea?

Yara is one of the largest Urea producers in the world, offering a unique Urea back-up supply. Our NOx control experts can provide you with technical support and advice to ensure that your SNCR Urea NOx control system is cost efficient and meets all the requirements needed.

Yara delivers the reagent of your choice from our unique network of plants offering a constant back-up in sourcing. We supply either solid Urea, typically for dilution on site, or Urea Solution in various concentrations.



Emma Inch
Emma Inch
Sales Manager - Base Chemicals