Flow Modeling
Computational Flow Modeling for SCRs and FGDs
Evonik Steag has blended “lessons learned” from their own completed SCR and FGD projects with the company’s extensive modeling capabilities and ongoing research and development activities to amass the best record in the industry for meeting NOx guarantees.
Modeling is critical when different NOx control technologies are used in combination to maximize NOx reduction. Evonik Steag’s modeling capability has been validated by testing and analyzing all of our own as well as many third party boiler, SCR and FGD units including those with low NOx burner and combustion modifications.
Evonik Steag has performed significant modeling work in the area of SCRs and FGDs focusing on:
- Flue gas flow
- Temperature distribution
- Ammonia and flue gas mixing
- Fly ash distribution.
Our in-house modeling consists of:
- CFD and/or physical flow modeling.
Results are used to provide advanced mixer designs that provide for intimate mixing of the flue gas with the ammonia while minimizing system pressure drop.
Evonik Steag has developed modeling capability for the mixing of ammonia and NOx upstream of the SCR reactor, in order to optimize the design and operation of the ammonia injection system.
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Proposed new LPA screens and modified economizer outlet duct is expected to result in a reduction in overall pressure drop of 1 – 1.5 inches w.c.
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Modeling and SCR-specific Issues
In addition to the mixing studies, Evonik Steag has performed extensive modeling to address SCR industry issues relating to “popcorn” or LPA ash and fly ash drop-out in ducts.
Modeling activities address:
- Geometric scale,
- Catalyst modeling,
- Ammonia injection modeling; and
- The relationship between the model and full scale installation
- Pressure drop.
As a result, Evonik Steag designed and supplied our patented LPA screens to numerous coal-fired units in Europe as well as the United States, which are equipped with SCR systems. As a result of this type of modeling, modification and/or additions to areas such as the economizer hopper have been made to allow for continuous and reliable SCR system operation.
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