How to Apply Non-Selective Catalytic Reduction Systems to Rich Burn Engines Successfully
Non-Selective Catalytic Reduction (NSCR) systems are widely used in the industry on rich burn engines for simultaneous reduction of oxides or nitrogen (NOx), carbon monoxide (CO), and volatile organic compounds (VOC). Although NSCR systems are easy to install and operate compared to some other control systems, there are some common pitfalls that can be avoided. Additionally, the application of NSCR becomes more challenging as emission limits decrease. Current Best Achievable Control Technology (BACT) limits are 0.15 b/BHP-hr for NOx and VOC, and 0.60 g/BHP=hr for CO, which are respectively 9.5, 26, and 60 ppm @ 15% oxygen. Special attention is required through all phases of the project to meet these low BACT limits: design, construction, start-up, and testing. Moreover, emerging New Source Review permit conditions, and Title V Periodic Monitoring and compliance Assurance Monitoring regulations add to the complexity by requiring more instrumentation and more frequent testing. Through specific examples of new installations and retrofits, the following issues will be discussed: getting the right people involved; technical and commercial specifications for catalysts and system; exhaust piping design and installation considerations; air fuel ratio control strategies; start-up/operational tests; fine-tuning procedures; instrumentation; emission testing; periodic monitoring (including a very brief discussion of portable emission monitors); maintenance.