Solving a complex NOx emissions challenge for Western Farmers Electric Cooperative
Western Farmers Electric Cooperative (WFEC) supplies power to cooperatives and other users in Kansas, New Mexico, Oklahoma and Texas and is part of the Southwest Power Pool (SPP).
Typical for this region, older gas fired, drum-boilers are utilized to back up wind generation. This will typically require the plant to rapidly change electric load to ensure grid stability. First generation RJM low NOx burners were installed in the late 1990s. The plant operated well from 2000 – 2016. Early 2017, the plant contacted RJM for assistance in NOx (less than 0.2 lbs/MMBtu) and CO (no current mandate) burner-tuning.
RJM (then SAS) performed a combustion audit to determine current condition and operation of burners. Site data proved crucial to proper diagnosis of operations as data taken during the site visit – observations and quantitative readings - strongly indicated one or two burners needed adjustment. The final Combustion Audit Report recommended the physical inspection of all burners in the windbox to ensure settings were correct.
Burners were subsequently inspected. One of the burners, identified during the combustion audit, showed actuator linkage slippage with a 100% open reading corresponding to only 40% open movement. In addition to resetting several of the burners, a furnace inspection showed dark carbon deposits on the burners.
A week after the inspection and with the revised settings now completed, the plant was re-started. While burner performance was greatly improved, control curves needed further tuning for the rapid load variations required to back up wind generation. Working with plant personnel, RJM developed new control curves that allowed the plant to rapidly change load, while optimizing NOx and CO.