【摘要】：2205雙相不銹鋼(2205DSS)作為優(yōu)異的耐蝕材料,在煉油系統(tǒng)中的應(yīng)用越來越廣泛,同時也暴露出了不少腐蝕問題,因此研究其在該環(huán)境中的腐蝕機理具有重要的意義。本論文主要采用腐蝕失重法、動電位極化曲線、循環(huán)極化曲線、電化學(xué)交流阻抗譜(EIS)、微區(qū)電化學(xué)掃描開爾文探針(SKP)、掃描電子顯微鏡形貌分析(SEM)、X射線能譜儀(EDS)和X射線光電子能譜法(XPS)等研究手段研究了 2205DSS在常壓塔典型環(huán)境中的耐蝕性能與腐蝕機理。首先,依據(jù)惠州煉化實際生產(chǎn)介質(zhì)情況,研究了 2205DSS在油相中的腐蝕規(guī)律和腐蝕機理,結(jié)果表明油相空白餾分中2205DSS的耐蝕性穩(wěn)定性高,受餾分和溫度影響不大,其中在常二段餾分中的腐蝕速率最大,脫后原油中腐蝕速率最低。同時,研究了油相中的無機S和C1對腐蝕的影響作用,結(jié)果表明S、C1對于腐蝕的有一定的加速作用。其次,以常減壓塔塔頂水相腐蝕為背景,進一步研究了 2205DSS在HCl + Na2S水溶液中的腐蝕機理。結(jié)果表明在含Na2S的HC1溶液中,HS_,H2S和OH-的競爭吸附對2205DSS的鈍化膜再生有阻礙作用,因此Na2S對2205DSS在HC1中的點蝕有促進作用(Na2S含量低于30mg/L時除外)。另外,HS_、H2S和Cl_的競爭吸附在不同濃度HC1溶液對腐蝕產(chǎn)生不同的影響:HC1濃度為3.60 g/L時,30 mg/L的Na2S對2205DSS的均勻腐蝕有抑制作用;而Na2S濃度大于100 mg/L時,鈍化膜溶解加快,局部有明顯的腐蝕坑出現(xiàn)。而HCl濃度為5.00g/L時,30mg/L的Na2S將極大地促進2205DSS的均勻腐蝕,腐蝕以析氫腐蝕為主。最后,研究了 2205DSS在高濃度NaCl溶液中的點蝕行為。研究結(jié)果表明其在35.00 g/L的NaCl溶液中的臨界點蝕溫度在40～60℃之間。降低NaCl的濃度,其保護電位升高,滯后環(huán)面積變小,說明其耐點蝕性能隨著NaCl的濃度減小而升高。單純改變pH值對2205DSS耐點蝕能影響不大。堿性的NaCl環(huán)境中,Na2S增加了均勻腐蝕速率,鈍化膜的局部自催化腐蝕效應(yīng)作用減小,發(fā)生點蝕的可能性降低。而在中性NaCl溶液中加入Na2S會導(dǎo)致鈍化膜溶解速率加快,點蝕電位降低,維鈍電流增加,耐點蝕性能降低。
[Abstract]:As an excellent corrosion resistant material, 2205 duplex stainless steel (2205DSS) is more and more widely used in oil refining system and has exposed many corrosion problems. Therefore, it is of great significance to study the corrosion mechanism of 2205 duplex stainless steel (2205DSS) in this environment. In this paper, corrosion weightlessness method, potentiodynamic polarization curve, cyclic polarization curve are used. Electrochemical Impedance Spectroscopy (EIS), Microarea Electrochemical scanning probe (SKP), scanning Electron Microprobe Morphology Analysis (SEM) X-ray Energy Spectrometer (EDS) and X-ray photoelectron Spectroscopy (XPS) have been used to study 2205DSS in typical environment of atmospheric tower. Its corrosion resistance and corrosion mechanism. Firstly, according to the actual production medium of Huizhou refinery, the corrosion law and corrosion mechanism of 2205DSS in oil phase are studied. The results show that the corrosion resistance of 2205DSS in the blank fraction of oil phase is high, but not affected by the fraction and temperature. The corrosion rate is the highest in the ordinary fraction and the lowest in the crude oil after desorption. At the same time, the effect of inorganic S and C1 in oil phase on corrosion was studied. Secondly, the corrosion mechanism of 2205DSS in HCl Na2S aqueous solution was further studied under the background of water phase corrosion at the top of the tower. The results show that the competitive adsorption of H2S and OH- in HC1 solution containing Na2S can hinder the regeneration of 2205DSS passivation film, so Na2S can promote the pitting corrosion of 2205DSS in HC1 (except when Na2S content is lower than 30mg/L). In addition, the competitive adsorption of HSH _ 2S and Cl_ in different concentrations of HC1 solution had different effects on corrosion. Na2S of 30 mg/L at the concentration of 3.60 g / L of HC1 could inhibit the uniform corrosion of 2205DSS, while when the concentration of Na2S was more than 100 mg/L, the dissolution of passivation film was accelerated. There are obvious corrosion pits in the area. When the concentration of HCl is 5.00g/L, 30 mg / L Na2S will greatly promote the homogeneous corrosion of 2205DSS, and the corrosion is mainly hydrogen evolution corrosion. Finally, the pitting behavior of 2205DSS in high concentration NaCl solution was studied. The results show that the critical pitting temperature in 35.00 g / L NaCl solution is between 40 鈩，

本文編號：2205368