Closing the Gap
All combustion processes generate nitrogen oxides (NOx). When exposed to solar radiation, these oxides form an air pollutant that is particularly difficult to eliminate: ozone. With Hitachi Zosen Inova’s DeNOx processes, nitrogen oxide is converted into harmless nitrogen and water – so completely, in fact, that current NOx emission standards are met easily. Hitachi Zosen Inova offers different SNCR and SCR systems to reduce nitrogen oxides. Different technologies represent the most economical and ecological solutions. It is especially worth mentioning how the new SNCR process DYNOR® closes the gap between the clssic SNCR process and the SCR process.
The Hitachi Zosen Inova DYNOR®
DYNOR® is the answer to Europe’s tightened nitrogen oxide limits. Simple in design and easy to install, the non-catalytic DYNOR® process closes the gap between the costly SCR process and the conventional SNCR process. It is an investment which pays off.
- Low nitrogen oxide levels with minimal ammonia slip
- Successful deployment and application in several EfW plants has confirmed the functionality of DYNOR® in full-scale, long-term trials.
The precise and dynamic DYNOR® process delivers the desired performance with significantly lower investment costs and energy consumption than the SCR process. Ammonia consumption is lower than in the conventional SNCR process thanks to precise temperature measurement and related injection.
DYNOR Process (3.1MB)
The Hitachi Zosen Inova SNCR Process
In the SNCR process (Selective Non-Catalytic Reduction), NOx reacts with ammonia (NH3) and is chemically converted into nitrogen (a natural constituent of air) and water vapour. Achieving high removal efficiency of NOx requires injecting more ammonia than is consumed. The excess can be removed downstream by the wet scrubbing process. With our patented process, the ammonia is recovered from the effluent and can be reinjected into the post combustion chamber.
An advantage of this process: dioxin formation in the flue gas is reduced significantly.
This process has been used successfully for many years in numerous waste processing plants. Experience demonstrates that the SNCR DeNOx process is capable of removing up to 90% of the nitrogen oxide from the flue gas.The equipment (ammonia water tank, pump rack, ammonia water and steam distribution pipes) takes very little space and can be added very easily to existing plants.
The Hitachi Zosen Inova SCR Process
The selective catalytic reduction (SCR) process is based on the reaction of ammonia or urea with nitrogen oxides (NOx) on a catalyst to remove NOx from flue gas. Ammonia water is injected into the upstream flue gas duct nozzles. The nitrogen oxides present in the flue gas are converted into nitrogen and water vapour at the catalytic surface. The catalyst itself with its internal catalytic modules is a maintenance-free black box.
The versatility of the SCR process reflects the fact that the catalytic reactor can either be installed in a high-dust arrangement downstream boiler or a low-dust arrangement between the initial flue gas cleaning system and the stack.
Ammonia water, pure ammonia, liquid or solid urea can be utilised as reactants, depending on the technical, economical and safety requirements.