BASF retrofit technology helps control emissions from power plants

Regulators have increasingly been tightening the belt on power plant emissions, with restrictions on nitrogen oxide (NOx) emissions forcing many utility suppliers to retrofit their gas turbines with catalyst technology that reduces those emissions.

When a utility supplier needed to retrofit its GE Frame 6 turbine it turned to BASF and Deltak Corporation, a leading developer of steam-generation equipment. The customer wanted a simple retrofit and minimal downtime. BASF and Deltak designed and installed a NOxCat™ catalyst for the GE Frame 6 combined cycle plant. Retrofitting a combined cycle turbine with the catalyst was an exception to the rule, but this system was chosen over a low NOx combustor due to cost-effectiveness and low maintenance. The gas turbine typically runs at a temperature of 992°F.

The original system had one exhaust by-pass damper leading to a Deltak heat recovery steam generator (HRSG). The entire SCR system was installed without the by-pass damper, and only existing ductwork connecting the turbine and by-pass had to be replaced. The retrofit required only a two-week scheduled shutdown to complete the tie-in.

The system reduced NOx emissions from 150 PPM to the required 9 PPM (over 94% conversion), while maintaining ammonia slip below 10 PPM.  No costly water or steam injection was required.

BASF and Deltak cooperated on the overall system design to ensure it met the tougher emission requirements. This included cold flow modeling to achieve both proper ammonia mixing and velocity distribution, as well as minimize pressure losses throughout the system. The total system pressure drop was only 3.1 inches W.C.