A 490 MW Natural Gas Fired Power Plant

A 490 MW Natural Gas Fired Power Plant

AIG Retrofit

Completion Date: November 2017

Turnkey Retrofit

Concord Environmental was selected by a Southwest US utility client to retrofit existing NOx reduction equipment on their Siemens 501F HRSG Selective Catalytic Reduction (SCR) systems.

Ammonia Injection Grid (AIG) tuning was performed by Concord and it was determined that the AIG design itself was causing poor ammonia distribution at the SCR catalyst. This resulted in ammonia bisulfate fouling (ABS) on the downstream HP/IP economizer tubes, as well as excessive ammonia usage. The utility selected Concord to then perform computational fluid dynamics (CFD) modeling to identify the problem areas, and develop a solution. The CFD modeling revealed that the design and location of the existing AIG needed to be changed. The existing ammonia distribution was very poor, and the modified AIG design showed a significant improvement.

Based on the successful CFD modeling, Concord Environmental was then selected by the client to design, fabricate and install the new AIG within a planned two-week outage. All of the design and fabrication work needed to take place in four weeks prior to the outage. All materials were delivered to the outage on time, and the demolition of the old AIG and installation of the new AIG went flawlessly, and was finished two days ahead of the schedule.

After startup, the ammonia flow to the SCR was immediately reduced by almost 25% due to the improved ammonia distribution and reduced ammonia slip. The plant also indicates that the ammonia salt formation has dropped off significantly. In a recent update from the utility to Concord, project management stated, “I again want to thank you for all of the work you put into our project and let you know that it appears to be a great success.”