The document discusses improvements made to a crude heater to address issues that arose after the client started processing shale crude. CFD modeling showed problems with uneven heat distribution and high tube metal temperatures in the radiant section. A proposed design with 18 ultra low NOx burners was modeled and showed improved flue gas flow, shorter flames, more even temperatures and heat flux. The redesigned heater was installed in 2014 and the client achieved longer run lengths and was happy with the performance improvements.