Analysis of corrosion mechanism and anti-corrosion strategy for absorption oxidation tower
To explore the fundamental causes for severe corrosion of the inner walls and internal accessory fittings of the absorption oxidation tower,the corrosion mechanism was analyzed through material analysis,macroscopic morphology observation,corrosion product characterization analysis,desalinated water and chemical detection,operating parameter analysis,and simulation experiment analysis.The results show that all materials meet the requirements of national standards;The concentration of CL-in the solution inside the tower is relatively high(254 mg/L),and there is a high content of dissolved oxygen(7.5 mg/L)in the desalinated water and the solution inside the tower.At the same time,there is also residual H2S in the solution(which is continuously introduced during the shutdown period);The EDS test results of corrosion products show that a certain chemical reaction occurs at the corrosion site.In summary,the main cause of corrosion is the adsorption of chloride ions on metal surface defects,making it difficult to repair the oxide film.Under high oxygen content conditions,oxygen reacts with the stainless steel substrate,causing the substrate to dissolve.Incomplete absorption of H2S leads to sulfidation of the oxide film on the stainless steel surface,resulting in a decrease in density.During the shutdown period,under the action of FeCl3 solution,the pitting corrosion further develops into a steady-state pitting corrosion pit,forming corrosion.The research results provide a direction for the investigation of the causes of corrosion of the same type of device,and provide specific reference measures for the anti-corrosion of the device,so as to avoid the serious consequences of device corrosion.
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