EFFECT OF PROCESS CONDITIONS ON FILM TEMPERATURE IN FIRED HEATERS

摘要

Variation in process conditions in fired heaters arise due to multiple circumstances, ofthese, throughput, inlet temperature and percentage of excess air are the most recurrent.Film temperature is an important parameter to be observed during the operation of this typeof equipment due to its influence in the development of coke on the heat transfer walls. Theconsequence of the building up of a fouling layer is the reduction of the thermo hydraulicperformance which introduces additional expenses and eventually forces plant shut downfor maintenance. In this work, an assessment of fired heaters performance is carried out at afixed outlet temperature and pressure. Results show that plant throughput variation demandhigher firing rates with the largest impact on film temperatures. Increased percentage ofexcess air also demands higher firing rates; however it does not show a strong impact onfilm temperatures. Finally the effect of inlet temperature appears not to shift the local filmtemperature profile from its original condition.