A new approach to predict fouling using a transient cfd model and dynamic mesh

In this work, a novel approach to predict the fouling layer growth on the internal surface of a tube by means of a transient CFD model is presented. The transient CFD model takes into account the complexity of the chemical and physical phenomena coupled with dynamic mesh. The dynamic mesh method is programmed by the user defined functions for allowing to grow the fouling on the internal surface of the tube. The study is carried out through the CFD in a 2-D computational domain which contemplates: the radial effects of the profiles of temperature and velocity, and the consumption and productions of species due to chemical reactions. This approach is applied for the fouling deposits on the internal surface of a tube of a petrochemical fired heater, due to the thermal cracking process of oil. Results of the temperature, the oil velocity, the concentration of the distillate and the coke distribution fields are obtained. Moreover, the fouling layer growth, due to the deposit and accumulation along the time, is predicted, and also, the tube metal temperature is computed to identify the "hot spots". According to the results, the fouling layer reduces the diameter of the tube until 24% at the exit in comparison with the clean tube, which leads to the apparition of the "hot spots" due to a high increment of the tube metal temperature at the exit.