The formation of coke during large-scale processing of hydrocarbons is an unwanted side process, which not only causes loss in production but also leads to decrease in heat transfer and furnace tube blockage. At high temperatures the coke may lead to carburization of the furnace material and ultimate catastrophic failure. In a petrochemical plant high temperature and wear resistant alloy components of radiant furnace coils were observed to suffer from severe erosion damages caused by impingement of coke particles, generated during ethylene cracking process. There are several regimes of interaction between erosion caused by coke activities and oxidation. Material removal involves a multi-impact mechanism. Scanning Electron Microscopy (SEM), X-ray Diffraction Analysis (XRD), Energy Dispersive X-ray (EDX) Analysis and Carbon-Sulfur (C-S) analyzer techniques were used to establish microstructural characteristics, compositional changes, chemistry of corrosion products and the mechanism of damages. This paper presents case studies on failure analyses conducted to establish cause and nature of erosion damages of the return-bendandthermowell of an
ethylene cracking radiant coil. Some remedial measures are suggested.
Keywords: Coke, ethane, carburization, erosion, impingement,
thermowell, return-bend, oxidation