Minimizing the Impact of SCR Catalyst on Total Generating Cost Through Effective Catalyst Management

For coal-fired boilers equipped with Selective Catalytic Reduction (SCR) NOx reduction technology, direct catalyst cost contributes to a major operating expense. Decisions regarding catalyst management have other significant impacts to generating cost, including outage time and frequency and parasitic load. Strategies for minimizing the impact to total generating cost while preserving system performance — generally referred to as catalyst management — are receiving greater attention. Approaches to managing catalyst can vary widely. Therefore, analysis of catalyst management strategies requires accurate predictive tools for assessing SCR system performance that have the flexibility to address a wide range of scenarios. These predictive tools may also be used to investigate performance issues that facility operators may encounter. However, until recently, operators have not had access to these tools, except through catalyst suppliers or consultants. In this presentation, various catalyst management strategies will be examined. Using an analysis tool recently adopted by several power plant operators and SCR technology suppliers, we will illustrate how such a tool can be used to optimize a catalyst management strategy to minimize the total cost of generation. Comparisons of model results to measured SCR performance at operating facilities will be presented. The model will be used to show operating trade offs for SCR operating parameters, such as NOx reduction, ammonia slip, catalyst outage frequency, catalyst usage, and parasitic load under a variety of scenarios. We will also discuss how the tool can be used to diagnose operating problems.