Stainless Steel Corrosion Behavior Study Of PTA Plants

PTA plants exposure to high concentrations of acetate, bromide ion, terephthalic acid, condensed water and other corrosive media, high temperature, high pressure environment to run the equipment, the use of extremely harsh conditions. At present, the domestic and overseas scholars has done some researches for chlorine ion acidic conditions of stainless steel corrosion behavior, but fewer researches for the bromine ion acetic acid environment with stainless steel corrosion behavior. It is of great significance to study the corrosion mechanism and preventive measures of stainless steel in acetic acid containing bromide ions environment for ensuring the efficient and safe operation of the PTA plant. By researching various corrosion factors to determine a feasible rehabilitation program to avoid the replacement will save considerable funds, and also for the future maintenance of the equipment, and even life extension has an important value.Through studying the stainless steel corrosion failure modes of the dryer shell in the PTA plant, we determined the main factors are the temperature, the Br-concentration and the Cl-concentration. Designing the orthogonal test program of the main factors and determine the best combination. Make the electrochemical tests under the test program and get the electrochemical polarization curve, passivation curve and the AC impedance curve. Regression analysis of the experimental data by using the SPSS software, and model the relationship between the316L stainless steel corrosion rate and the corrosion impact factors. Research the uniform corrosion factors of the PTA plant dry machine stainless steel shell through the model. In the same way, model the relationship between the breakdown potential and the corrosion reaction resistance with the corrosion impact factors. Then verify the reliability of the model. Analysis of factors of316L stainless steel pitting corrosion, and then made the appropriate anti-corrosion measures to provide a theoretical basis for the online monitoring of corrosion and maintenance of the dryer shell stainless steel material in the PTA plant. It has certain theoretical significance and application value to improving the PTA plant stainless steel equipment reliability, prolonging the security operation cycle, reducing production cost, ensuring t he safety of t he production and economic benefit of t he enterprise.