The Damage Mechanism Analysis Of Ethylene Cracking Furnace Tube And Research Of Safety Countermeasures

The ethylene cracking tube is a key component of the ethylene unit. Because of the complex and harsh service conditions, furnace tubes often fail before reaching the designed lifetime, which leads a great waste of materials and constitutes a dangerous hazard to the safety production of the enterprises.This paper is based on the failure analysis of two different corroded radiation segments of furnace tubes. By means of chemical composition analysis, macro morphology observation, metallographic inspection, SEM and EDS, the failure mechanisms of each tube were found out. In order to get the exact reasons related to the failure, comparative analysis of boiling ranges of HVGO and NAP were carried out. The results demonstrated that the local concentration of the corrosive media, which happened when the temperature reached the HVGO’s end point of distillation, was a key reason leading to failure, and this conclusion also explained why the corrosion happened only in the specific environment and within a specific temperature range. Then the finite element analysis about the flows of the fluid inside the tube was conducted, the results showed the discontinuous construction of the welding joint can enhance the local turbulence and accelerate the corrosion. At last, on the basis of the failure reasons found out, pertinent safety countermeasures were came up with. The engineering practice demonstrates the measures are effective and the research is of great value.