Low NOx Retrofit on an Existing Heater with a Small Radiant Section

Paper from the AFRC 2014 conference titled Low NOx Retrofit on an Existing Heater with a Small Radiant Section by T. Gilmartin.

Conventional logic in retrofitting a heater to meet Low NOx environmental limits suggests that you should only fit a burner that just meets the NOx requirement. A main factor in this logic is flame size where the critical factor is length - low NOx burner flames get longer larger the lower the NOx target is. But is this always true?! Of course you can always fit any burner - but will you maintain the same fired duty? This paper describes: The history: Six years ago, BP asked for a deferment to retrofit low NOx burners, as they saw no existing burner type available that would not cause a rate reduction with a flame fitting in the fire box. The thought process: Emission limits require 100 mg/Nm3. Which burner, if any, could meet compliance requirement for retrofit activities? Burner picked: CUBL HC burner seen on test - potential to retrofit and not sacrifice rate? Duty of care: visit other user, CFD and test Steps taken as a result of CFD and testing: End burner modifications after CFD showed potential end wall issues. Commissioning: demonstrated performance at full rate. Test runs at load showed 33ppm NOx (66mg/NM3) • An accurate CFD model assisted in gaining confidence that the retrofit would not cause issues. Show CFD and video of test. Lessons: CFD gives confidence. Paradox - sometimes fitting an ultralow NOx burner will perform better than a low NOx burner.