Start-up burner modifications to reduce NOx

The Challenge

RJM was required to engineer, model and supply start-up burner optimisation and modifications to reduce NOx, with BOOS and IFGR, from 118 ppm (242mg/Nm3) at 3% O2 to less than 83 ppm, whilst maintaining 108 ppm CO.

The plant, manufactured by Combustion Engineering, consisted of a 62 MWe unit firing natural gas through 12 burners, with three rows of four on the front wall.

RJM Solution

Following an initial performance study, RJM deployed its Burner Modification Technology and Combustion Tempering Technology to reduce NOx from 118 ppm to 83 ppm. The baseline figure was measured with two of the top burners out of service and IFGR because of air heater problems at 51 MW load.

After meeting Entergy’s requirements, the system was pushed to the low NOx levels of 72 ppm (148mg/Nm³) @ 3% O₂. When Combustion Tempering was added, a maximum reduction of 39% was achieved. CO₂ was within the 108 ppm limit (135mg/Nm³) across the entire load range and for the lowest NOx achieved.

Technical Data

RJM performed full burner modifications, which incuded the installation of new low-NOx centre-fired gas header assemblies with staged gas pokers and radially and circumferentially staged flame stabilisers.

Combustion Tempering, RJM’s patented technology, was supplied to further reduce NOx.

The burmer igniters, oil guns, secondary air dampers and throats / refractory were all  replaced or repaired, as necessary.