SCR Tuning

CC&E recommends annual tuning of SCR ammonia injection grids to maximize ammonia utilization, thereby minimizing operating and maintenance costs. We use an automated sampling system to extract flue gas from a multi-point grid downstream of the catalyst bed. The O2 and NOx constituents of this grid are mapped across the entire SCR outlet duct. Then, based on this spatial data, the ammonia injection grid is incrementally adjusted to achieve a uniform NOx levels (minimized NOx standard deviation RMS)across the outlet duct. CC&E can also couple the outlet spatial data with a corresponding SCR inlet sample grid. This allows us to adjust ammonia valves to achieve a uniform NOx REDUCTION (minimized NOx reduction std. dev. RMS) across the duct. This brings into account inlet NOx distribution. We have employed both tuning techniques for various clients.

In both cases, CC&E measures ammonia slip downstream of the SCR to ensure that these levels are below design specs. We use an extractive wet method for this measurement, have the capability of sampling from several points simultaneously and can quickly analyze the results onsite for timely feedback.

CC&E also has the capability of determining SO2 to SO3 conversion across the reactor. We can easily include an SO2 analyzer with our automated sampling train for SCR inlet SO2 levels. We measure SO3 at both the catalyst inlet and outlet using either Method 8 or the controlled condensation method, depending on client preference.