Abstract
It is well known that the emission of greenhouse gases has become the main cause of climate change.These greenhouse gases include CO2,CH4,N2O,etc.Among them,the large amount of CO2 emissions caused by the combustion of fossil fuels has attracted much attention.Carbon capture and storage(CCS),as a cutting-edge technology for mitigating greenhouse gas emissions,has drawn close attention from the international scientific and technological as well as industrial communities.During the storage of CO2,carbon source impurities such as SOx,O2,NOx,and H2S are inevitably present.Once water phase precipitates,carbon steel pipelines will face severe corrosion,leading to safety accidents such as high-pressure CO2 leakage.
The effects of various carbon source impurities on the metal materials corrosion behavior cannot be overlooked during the process of CO2 storage.In this work,high-temperature and high-pressure simulation tests are conducted on P110 tubing steel at 90℃with the content of carbon source impurity SO2 being 0%,2.5%and 5%respectively.Techniques such as laser confocal microscopy,SEM,EDS,EPMA,HRTEM,Raman spectrum and XPS are employed to analyze the film formation mechanisms of corrosion product layer and corrosion characteristics of P110 tubing steel.In aqueous solutions,SO2 dissolves to form H2SO3,which dissociates into HSO3-and SO32-.Under anaerobic conditions,SO32-can be reduced to S2-,reacting with Fe2+to form FeS.In highly acidic or high-SO2 environments,S2-further combines to form S22-,leading to FeS2 formation.XPS analysis reveals that the sulfur species in the corrosion product film include FeS,FeS2,FeSO3,and FeSO4.Raman spectroscopy and XRD confirm the presence of these compounds,with FeS and FeSO3 dominating at higher SO2 levels.The formation of non-protective FeSO3 and the porous nature of the film significantly reduce its protective capability,accelerating corrosion rates.The results show that when there is no SO2,the corrosion product film is mainly composed of dense FeCO3 and a small amount of CaCO3,which has certain protective properties,but the uniform corrosion rate of the matrix material is still relatively high.With the increase of the SO2 content,the delamination phenomenon of the corrosion product film gets more obvious.The corrosion products present an irregular microscopic morphology,and the lattice fringes in the flower bracket-like regions are not distinct.The outer layer shows amorphous FeS,needle-like FeS2 and plate-like FeSO3,while the inner layer consists of FeCO3 and Fe3O4.The introduction of SO2 significantly increases the penetration depth of S element in the membrane(from 120 μm to 175 μm),and leads to the corrosion product membrane becoming loose and porous,with a decline in protection.When the SO2 content is 5%,Penetrating cracks appear in the corrosion product film,and the contents of FeS and FeSO3 significantly increase.At the same time,the cooperative effect of high temperature,high pressure and the acidic environment enhances the oxidizability of SO32-.Meanwhile,the structural defects of the corrosion product film provide channels for the continuous oxidation of S elements,leading to an increase in the proportion of high-valent S elements(S4+),which further exacerbates local corrosion and pitting corrosion.关键词
P110油管钢/碳源杂质SO2/CO2埋存/腐蚀产物膜/S元素氧化Key words
P110 tubing steel/carbon source impurity SO2/CO2 storage/corrosion product film/S elements oxidation分类
矿业与冶金
