Catalytic gas cleaning
SCR for removal of NOx & CO/VOC
GEA is well known for its long-term proven application of Selective Catalytic Reduction (SCR) for NOx control.
GEA develops and manufactures highly efficient denitrification systems, tailor-made to customer needs. The SCR technology is the best available NOx removal (DeNOx) process, it selectively reduces NOx emissions by injecting Ammonia into the exhaust gas upstream of a catalyst.
Current and future requirements on NOx and VOC control are met with GEA’s advanced catalytic reduction technology. The high-activity catalyst and low-pressure drop result in a cost-effective NOx reduction.
Main Benefits
- Provide highest SCR performance efficiency with minimum ammonia slip
- Proven reliability over extended years of operation
- Reduced overall SCR pressure drop
- Ability to mitigate the catalyst´s poisoning and extend the life of catalyst
- No catalyst fouling thanks to optimized inlet temperature
- CAPEX and OPEX considerably lower than other DeNOX-Systems
Working Principle
Working Principle of SCR for NOx removal
An aqueous ammonia solution or urea is injected through two-fluid nozzles (ammonia/compressed air) and into the ductwork upstream of the SCR where it immediately evaporates. The adequate mixing of ammonia is ensured by a static mixer installed in the ductwork downstream of the ammonia injection points. The gas and ammonia mixture enters the unit from the top and exits horizontally at the bottom.
A gas distribution system (swirl breaker) ensures an adequate gas distribution over the entire cross-section of the unit. The reaction between ammonia and NOX is enhanced by the presence of the catalyst bed, converting it into nitrogen (N2) and water. The catalyst is cleaned in an intermittent fashion (in 24-hour intervals), if required. The ammonia feed rate is controlled by the NOX outlet concentration of the gas.
The SCR in the glass industry is situated after the dedusting system and can also be installed in already existing plants.
GEA offers the SCR for cement plants in low-dust arrangement, situated after the bag filter or electrostatic precipitator.
As the temperature after dedusting can be quite low, a gas-gas-heater is required (recuperative or regenerative) to preheat the gas.
The temperature needs to be further heated up to the temperature required for the DeNox-catalyst. This can be achieved either by an internal heat source from preheater waste gas or clinker cooler waste gas or by an external heat source such as a natural gas burner.
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