Study On The Corrosion Environment Of The Air Cooled Heat Exchanger On The Top Of Fractionating Tower

In this paper,the corrosion behavior of the inner tube of the header of the fractionator in FCC unit was studied.Based on the analysis of the causes of pitting corrosion of equipment materials,the main factors affecting the corrosion of the head tube of the Catalytic Cracking Fractionator were obtained,such as chloride ion,sulfur ion,temperature and pH value.The study chose three kinds of commonly used materials on-site bundle?10# steel,20# steel and 304 steel?in solution,simulation of the actual working medium of various factors on the corrosion behavior of materials,to provide reference for corrosion protection system.The main influencing factors of Cl^-concentration,S^2-concentration,temperature and pH value were tested one by one,and the polarization curves and AC impedance spectra were obtained.The polarization curves were analyzed,and the corrosion potential Ecoor and the annual corrosion rate were obtained by fitting,and then the parameters of Ip and pitting potential Eb were obtained.The results were analyzed to determine the influence of various factors on the corrosion behavior and the degree of significance.For the AC impedance spectrum,the factors which influence the corrosion behavior are determined by establishing the equivalent circuit.The polarization curves and impedance spectra showed that the corrosion of 10# steel,20# steel and 304 steel increase with the increasing of chloride ions and sulfide ions;analysis and comparison showed that in the range of temperature and pH,304 steel is the most resistant to corrosion,and then the is the 10# steel,the worst is 20#.For three materials,the increase in temperature promotes corrosion of the material,increases in pH,and inhibits the corrosion of the material.