Abstract
Energy costs represent about 65% of the running cost of a chemical, petrochemical, or refining plant. Furnace fuel represents the largest percent of this cost as it consumes large amounts of fuel to produce the necessary heat duty. Therefore, it is important for fired heaters to have an efficient system for monitoring operational parameters to reach the optimum performance and minimum stack emissions with an acceptable safety levels. One of the most critical operational parameters to be measured is the tube metal temperature (TMT) inside the radiation section. Excessive TMT can accelerate tube creep, hydrogen attack, and external and internal corrosion of the tube wall. The objective of this work is to develop a program capable of calculating precisely and continuously TMT instead of using external pyrometers that measure it only at certain times for heaters not equipped with thermocouples. The program can also be a predictive tool for estimating the changes of TMT at various temporarily conditions such as raising the fired heater capacity. Four case studies were investigated; the results showed a good agreement between the actual results and the proposed program results with a maximum deviation lower than 6%, which indicates the validity of the introduced program.