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IONEX Research Corporation produces high performance equipment used to protect the environment and personnel from hazardous airborne chemicals and contaminants (click here to visit the IONEX website). IONEX was requisitioned to deliver a Thermal Catalytic Oxidizer/ Selective Catalytic Reducer for filtering offgas emitted from a nuclear waste treatment facility.

The unit consisted of a heat exchanger, a heater, three banks of oxidizing catalysts and three banks of reducing catalysts. Positioned in the offgas stream between the oxidizing and reducing catalysts was an ammonia injection grid that supplied anhydrous ammonia to the offgas stream for reducing NOx. As part of the requisition, their customer required that IONEX demonstrate that the ammonia is distributed evenly into the offgas stream to ensure adequate NOx reduction. IONEX turned to Endesin to design the ammonia injection grid and spec the appropriate, commercially available nozzles.



The steps used to design the ammonia injection grid were as follows:

  • The first step was to create a model for the duct that connects the oxidizing catalyst bank with the reducing catalyst bank. The model was simplified for analysis and split to take advantage of symmetry.
  • A preliminary design for the ammonia injection grid was established based on past experiences and industry best practices and the grid was modeled and placed within the duct model.
  • A commercially available injector was selected again based on past experience and industry best practices and a simplified model of the injector was added to the grid at the preliminary injector locations.
  • Prior to beginning this analysis, a CFD analysis on the entire TCO/SCR unit was performed to determine the flow properties through the catalyst banks and the results from this analysis were used to determine the inlet flow to the duct.
  • The ammonia injection was added to the analysis as a tracer fluid so that its concentration could be measured during postprocessing.
  • The design of the grid and the injector selection was modified based on the analysis results and the analysis was repeated. This cycle continued until the desirable ammonia distribution pattern was achieved.



NX Advanced Simulation was used as the pre and post processor and the solver used was NX Flow.



IONEX is able to secure projects that require engineering capabilities that other firms can't provide because they can rely on Endesin to for the most advanced engineering tools available as well as the expertise needed to use them effectively. This project was yet another example of Endesin’s engineering capabilities being seamlessly integrated into an existing engineering team to take on a new level of engineering complexity.