Corrosion and Fouling in Petrochemical Environments

     Although petrochemical process streams are primarily composed of hydrocarbons, corrosion and fouling is observed in various locations and environments in operating plants.  An electrochemical high temperature and high pressure facility is used to study the corrosion behaviour of carbon, low-alloy and stainless steels in several petrochemical environments.  The electrochemical techniques such as cyclic voltammetry and open circuit potential measurements are used to study the effect of temperature, water concentration and rotation rate on the initiation of corrosion/fouling on carbon and stainless steels in several petrochemical mixtures.  The experiments are conducted using a quasi-reference Ag metal electrode.  Initial results suggest that corrosion rates vary with conductivity, which are controlled, by varying the concentration of water.  Scanning electron microscopy and energy dispersive X-ray analysis is used to look at the nature of the deposit formed after applying the aforementioned electrochemical techniques.  Electrochemical impedance spectroscopy (EIS) is used to determine the onset of fouling on carbon and stainless steels in raw pyrolysis gasoline and quench tower bottoms as a function of surface roughness.  A number of fouling characteristics including the time for initial surface coverage, the rate of film formation and the properties of the surface film have been studied using EIS.