Research On Corrosion Behavior And Safety Measures Of MDEA Solution Reboiler In Sour Natural Gas Purification Plant

The serious corrosion of the acid natural gas purification plant equipment easily causes device perforation and rupture.As consequences,gas leaks,which not only affects the work safety of natural gas purification plant,but also causes environmental pollution or even catastrophic accidents.Under the circumstances of reboiler,321 steel tube and deflector baffle 16Mn? are seriously corroded in high concentration of H2S and CO2.This paper researches on the corrosion of reboiler and gives anti-corrosion methods accordingly.According to the SEM analysis on the site-taken tube,there're mainly uniform corrosion,pitting corrosion and localized corrosion issues.Laboratory simulation reboiler work environment mainly studied 45,N80,J55,VM125HC,304,316,316L and reboiler 321 and 16Mn? steel,and made SEM and EDS elemental analysis on the corroded test pieces.Combining the analysis and the weight loss,the degree of corroding of these steels from high to low are 16Mn?>45>J55>N80>VM 125HC>304>316>316L>321,and deflector baffle 16Mn? can't stand the high concentration of H2S and CO2 under high temperature environment,while 321 steel tube worked just fine.In order to do a better research on the corrosion of the co-existence of H2S and CO2 under high temperature environment,we hanged pieces in 3 desulphurization plants for one year.The corrosion rate and corrosion weight loss chart explain the corrosion resistance under the reboiler environment.Four of these steel pieces(316,304,316L,321)have a good anti-corrosivenes,which can be considered as replacement materials to deflector baffle.Plain carbon steel J55,N80 and high sulfate-resistance steel VM125HC have shown being corroded.Gas phase corrosion area in three purification plants exhibits serious corrosion.Against the reboiler corrosion issue,the corresponding anti-corrosion measures are as follows.For starters is to select the correct corrosion resistance materials.According to reboiler media,flow rate,temperature,etc.,appropriate improvement measures are proposed.Among these measures,deflector baffles 16Mn? steel is recommended to replace the material.Due to the pitting corrosion of the tube,we ran Cl-test on MDEA solution,so the water filled in the reboiler must be strictly controlled the content of oxygen and ions.Laboratory also ran anti-corrosion experiments on coating,corrosion inhibitor like Imidazoline and electrodeposition materials.The results shows that coating,corrosion inhibitor and electrodeposition materials all three have a good anti-corrosiveness.