SCR/ DeNOx denitrification system

If NOx is present in the exhaust air, the usual oxidation processes are not suitable. Selective catalytic reduction (SCR) or non-catalytic processes (SNCR) are used here.

Operating principle

If required an SCR system (selective catalytic reduction) can be combined with all exhaust air purification systems.

Using a catalytic converter, ammonia or urea is injected as a reducing agent to reduce the NOx (NO/NO2) concentrations in the exhaust gas, mixed and fed to the catalytic reactor. The correct dosage of the reducing agent is calculated and continuously controlled on the basis of the NOx concentration and the exhaust air volume.

In the catalytic converter, ammonia or urea is used to reduce the NOx to nitrogen N2 and water.

An economizer can then be installed to recover the remaining heat energy.  

It is also possible to reduce the NOx concentration without a catalytic converter; this is referred to as an SNCR system (selective non-catalytic reduction). The disadvantage is a lower efficiency and significantly higher temperatures required for the reduction. By first injecting a reducing reagent (e.g. NH3) into the exhaust gas flow, the NOx can be reliably converted into harmless N2 and H2O by catalysis.

Industry solutions

An SCR system is used wherever increased nitrogeneoxide concentrations occur and need to be cleaned.

Catalytic exhaust air purification is used in applications where defined process conditions exist and possible catalyst poisons can be excluded. The catalysts and operating conditions are adapted to the respective area of application.

This is taken into account in the following industrial sectors, among others:

  • Chemical/pharmaceutical industry
  • Petrochemical industry
  • Mineral wool production

Technical data

Exhaust air volume                                              

500 bis 200.000 Nm³/h
Typical contaminants         NOx
Pollutant concentrations  low to high loading
Temperature range (SCR)        300 – 350°C
Temperature range (SNCR)    850 - 950 °C


  • Suitable for all applications with increased NOX concentrations
  • Can be combined with various system types
  • Stand-alone operation possible
  • Individual adaptation to the process conditions
  • High utilization of the catalyst due to flow-optimized design
  • Optimized/low energy requirement
  • Can be integrated into the production system
  • Low maintenance effort
  • Easy accessibility and therefore good options for cleaning and catalyst replacement
  • Potential for heat recovery with water, thermal oil or air
  • Electric heating as an alternative to gas is possible
  • Low space requirement due to the compact design and comparatively low weight
  • The system can be installed indoors/outdoors, horizontally/vertically, on a foundation/steel structure or on a roof

Further products

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