Emissions performance can be impacted by factors anywhere from fuel combustion to stack monitoring, so it is important to look at the whole picture when evaluating emissions control system performance. The accuracy and quality of insight provided by an Environex Full SCR System Evaluation delivers value that is unmatched in the industry. Our comprehensive evaluations enable us to pinpoint remaining catalyst life, identify causes of performance loss, determine the limiting operating case for your system, and distinguish SCR system problems from SCR catalyst problems.
Our time-tested methodology includes a combination of catalyst sample “mapping”, plant operating data analysis, SCR system inspection, and overall emissions control system inspection. This combination provides us with a complete set of data and the proper perspective for evaluating all factors that impact stack emissions performance. Our experience ranges from internal combustion engines and on-site power generation to large Frame turbines and coal boilers (and everything in-between), so we have seen it all.
SCR Sample Mapping
Our engineers collect a representative set of catalyst samples from various locations throughout the catalyst cross section to “map” the overall catalyst activity level. Our methodology enables us to account for any variations in bulk catalyst activity caused by deviations in exhaust flow patterns, temperature distribution, and contaminant loading. It also eliminates uncertainty caused by sample-to-sample variation and ensures that you are not relying on a single data point for projecting remaining catalyst life.
Each SCR catalyst sample is tested for NOx conversion performance, chemical contaminant levels, and physical characteristics. Performance tests simulate plant operation so that we may project catalyst performance across all operating modes.
Operating Data Analysis
In addition to catalyst test results, we look at plant operating data for a set of parameters that characterize overall plant emissions performance. This analysis allows us to evaluate overall plant emissions performance and identify the catalyst performance requirements for each plant operating mode (partial vs. baseload, fired vs. unfired, etc.).
The catalyst performance test results are evaluated in light of the different performance requirements identified in the plant operating analysis to determine which operating mode is limiting for your unique system. Inconsistencies between the catalyst test results and operating data analysis enable us to identify system (non-catalyst) problems that are impacting overall plant emissions performance.
SCR System Inspection
While our engineers are on site to collect catalyst samples, they also perform a complete inspection of the overall emissions control system. The inspection focuses on the physical condition of the bulk catalyst, the catalyst housing and seals, the operability of the reagent injection system, and other upstream and downstream system components. CO catalysts are also inspected if they are included in your system.
Maintenance recommendations that will improve overall emissions performance are identified during the site inspection. Any hardware issues that may be negatively impacting system performance are also identified.
CO Catalyst Testing
For systems that include a CO oxidation catalyst, the CO catalyst should be tested in conjunction with the SCR catalyst. There are inherent trade-offs in NOx and CO formation during fuel combustion, so performance of the SCR and CO catalysts must be balanced to ensure reliable overall system emissions performance.
The CO catalyst may also have other impacts on SCR system performance, including potential flow distribution issues due to plugging or SCR catalyst poisoning issues due to migration of the active CO catalyst washcoat material onto the SCR catalyst.