Application of Combustion Hot Spot Analysis to Process Furnace with Arbor Coils

Hot spots are among the most serious operational issues in furnaces as they may result in the destruction of tubes. Hence, it is essential to locate such hot spots precisely on the tube surfaces inside the industrial furnaces in order to secure a safe design and operation. In the current study, we have extended the model proposed by Talmor in order to precisely locate the combustion hot spots on the surface of the tubes inside process furnaces with arbor coils. These furnaces are mostly used in catalytic reforming units. The Talmor model is one of the best models for analyzing combustion hot spots on the tube surfaces of industrial furnaces. This model is developed by considering the furnace geometry and arrangement (tube arrangements and burner positions). In the current paper, we have derived and extended the equations formulated by Talmor for furnaces with arbor coil. As the second step, a specific furnace already installed in a catalytic conversion unit of a refinery has been selected for the sake of modeling. The modeling of the preceding furnace was completed using the code prepared for this purpose. The results have been used not only for analyzing the hot spots but also to model the heat flux profile inside the furnace. Upon modeling the furnace, the location of the hot spot on the 20th coil was predicted which was consistent with the experimental results.