本文選題：儲(chǔ)罐底板 + 陰極保護(hù)��； 參考：《西南石油大學(xué)》2015年碩士論文

【摘要】：儲(chǔ)罐底板一旦發(fā)生腐蝕穿孔,會(huì)帶來(lái)巨大的經(jīng)濟(jì)損失,影響整個(gè)站場(chǎng)正常的生產(chǎn)秩序,還會(huì)對(duì)環(huán)境造成嚴(yán)重的污染。本文以牙哈裝車南站1#儲(chǔ)罐底板為研究對(duì)象,從儲(chǔ)罐運(yùn)行現(xiàn)狀出發(fā),對(duì)儲(chǔ)罐底板發(fā)生腐蝕的機(jī)理進(jìn)行了研究,分析得到儲(chǔ)罐底板有腐蝕穿孔的風(fēng)險(xiǎn),驗(yàn)證了1#儲(chǔ)罐底板采用外加強(qiáng)制電流陰極保護(hù)防止罐底板外側(cè)發(fā)生腐蝕的必要性。同時(shí)在儲(chǔ)罐底板陰極保護(hù)系統(tǒng)有效性檢測(cè)過(guò)程中發(fā)現(xiàn)1#儲(chǔ)罐的長(zhǎng)效參比電極安置在罐底板周圍,罐底板中心的保護(hù)電位難以通過(guò)測(cè)量獲得,罐底板中心保護(hù)效果的預(yù)知性差,增加了罐底板腐蝕穿孔的風(fēng)險(xiǎn)。因此建立儲(chǔ)罐底板陰極保護(hù)的電位分布數(shù)學(xué)模型,運(yùn)用數(shù)值計(jì)算方法模擬計(jì)算儲(chǔ)罐底板的電位分布,對(duì)于提高陰極保護(hù)效果,確保儲(chǔ)罐底板的安全具有非常重要的意義。 針對(duì)儲(chǔ)罐底板深井陽(yáng)極強(qiáng)制電流陰極保護(hù)系統(tǒng)構(gòu)成的特點(diǎn),建立了三維半無(wú)限域物理模型,深井陽(yáng)極簡(jiǎn)化為列狀集中點(diǎn)源�；诤汶娏骼碚�,推導(dǎo)得到Poisson方程為電位分布的控制方程。根據(jù)實(shí)際情況,考慮罐底板金屬的極化特性,對(duì)邊界條件進(jìn)行研究,最終建立了儲(chǔ)罐底板陰極保護(hù)電位分布數(shù)學(xué)模型。分析比較有限差分法、有限元法和邊界元法三種方法的優(yōu)點(diǎn)和缺點(diǎn),選取邊界元法作為該數(shù)學(xué)模型的求解方法。 根據(jù)邊界元法的求解原理,推導(dǎo)得到了三維半無(wú)限域模型的基本解,采用等參四邊形單元對(duì)罐底邊界進(jìn)行離散,電位場(chǎng)的數(shù)學(xué)模型經(jīng)過(guò)邊界離散后化為代數(shù)方程,陰極保護(hù)電位分布問(wèn)題變?yōu)榍蠼獯鷶?shù)方程組的數(shù)學(xué)問(wèn)題。采用高斯積分法與退化單元法計(jì)算不含源點(diǎn)單元影響系數(shù)和含源點(diǎn)單元影響系數(shù)。為了求解模型,采用分段擬線性化法對(duì)陰極極化曲線進(jìn)行了處理。編制了基于邊界元法的儲(chǔ)罐底板陰極保護(hù)電位分布仿真程序,并采用COMSOL軟件模擬驗(yàn)證計(jì)算結(jié)果,模擬結(jié)果與儲(chǔ)罐底板陰極保護(hù)電位分布程序計(jì)算結(jié)果基本吻合,驗(yàn)證本文建立的數(shù)學(xué)模型及計(jì)算方法可以用來(lái)預(yù)測(cè)儲(chǔ)罐底板的陰極保護(hù)效果。計(jì)算結(jié)果表明,1#儲(chǔ)罐整個(gè)底板外側(cè)的電位值都在保護(hù)范圍之內(nèi),電位大小在-0.971V～-1.115V之間,電位最正值在罐底板中心附近。罐底板邊緣的電位負(fù)于罐中心的電位,且近陽(yáng)極點(diǎn)的電位負(fù)于遠(yuǎn)陽(yáng)極點(diǎn)的電位。 在運(yùn)用邊界元法計(jì)算儲(chǔ)罐底板陰極保護(hù)電位分布的基礎(chǔ)上,分別研究了包括陽(yáng)極設(shè)置參數(shù)、土壤電阻率等因素對(duì)儲(chǔ)罐底板陰極保護(hù)電位分布的影響。研究發(fā)現(xiàn)：隨著深井陽(yáng)極埋深增加,陽(yáng)極井長(zhǎng)度增長(zhǎng),或是增加深井陽(yáng)極距儲(chǔ)罐的距離,儲(chǔ)罐底板電位向正方向偏移；隨著深井陽(yáng)極輸出電流增大,陽(yáng)極井?dāng)?shù)量增多,儲(chǔ)罐底板電位向負(fù)方向偏移,電流大小應(yīng)保持在6A～8A之間,實(shí)際工程應(yīng)用中單個(gè)儲(chǔ)罐一般設(shè)置1～2口陽(yáng)極井為宜；土壤電阻率增大,儲(chǔ)罐底板電位均向正方向偏移,電流大小和土壤電阻率影響電位分布最為顯著。
[Abstract]:Once the tank floor is corroded and perforated, it will bring huge economic loss, affect the normal production order of the whole station and cause serious pollution to the environment. This paper takes the 1# storage tank floor of the South Station of yazakhstan loading car as the research object. From the running status of the tank, the mechanism of the corrosion of the tank floor is studied, and the storage is analyzed and stored. The tank floor has the risk of corrosion and perforation, which proves the necessity of preventing the corrosion of the bottom plate of the tank floor by the forced current cathodic protection of the 1# storage tank. At the same time, it is found that the long effect reference electrode of the 1# storage tank is placed around the bottom plate of the tank in the process of the effectiveness detection of the cathodic protection system of the tank floor. The protection potential of the tank bottom center is difficult. Through the measurement, the prediction of the center protection effect of the tank bottom is poor, which increases the risk of corrosion perforation of the tank floor. Therefore, a mathematical model of potential distribution for the cathodic protection of the tank floor is established, and the potential distribution of the tank floor is simulated and calculated by the numerical calculation method, so as to improve the protection effect of the negative pole and ensure the safety of the tank floor. It is often important.
In view of the characteristics of the Fukai Yogoku forced current cathodic protection system of the tank floor, a three-dimensional semi infinite field physical model is established. The deep well anode is simplified as the column central point source. Based on the constant current theory, the control equation of the Poisson equation as the potential distribution is derived. According to the actual situation, the polarization characteristics of the metal in the tank floor are considered, and the boundary is considered. The conditions are studied, and the mathematical model of the cathodic protection potential distribution in the tank floor is established, and the advantages and disadvantages of the three methods, finite difference method, finite element method and boundary element method are analyzed and compared, and the boundary element method is selected as the solution of the mathematical model.
According to the principle of solving the boundary element method, the basic solution of the three-dimensional semi infinite domain model is derived. The isoparametric quadrilateral element is used to discrete the boundary of the bottom of the tank. The mathematical model of the potential field is transformed into an algebraic equation after the boundary is discrete. The problem of the distribution of the cathodic protection potential becomes the mathematical problem of solving the algebraic equations. The Gauss integral method is used. In order to solve the model, a piecewise quasi linearization method is used to deal with the cathodic polarization curve. A simulation program for potential distribution of cathodic protection in tank floor based on boundary element method is developed, and the simulation results are simulated and verified by COMSOL software. The results are in good agreement with the calculation results of the cathodic protection potential distribution program of the tank floor. The mathematical model and calculation method established in this paper can be used to predict the cathodic protection effect of the tank floor. The calculation results show that the potential value of the whole floor of the 1# tank is within the range of protection, and the potential is between -0.971V and -1.115V. The potential is most near the center of the tank floor. The potential at the edge of the tank plate is negatively related to the potential of the tank center, and the potential near the anode is negative to the potential of the far Yang pole.
On the basis of using the boundary element method to calculate the cathodic protection potential distribution of the tank floor, the influence of the parameters of the anode setting and the soil resistivity on the cathodic protection potential distribution of the tank floor is studied. The study shows that the length of the anode well grows with the depth of the deep well anode increase, or the distance of the deep well anode tank. The potential of the tank bottom is shifted to positive direction; with the increase of the output current of the deep well anode, the number of anode wells increases, the potential of the tank bottom is shifted to negative direction, and the current size should be kept between 6A and 8A. In actual engineering applications, 1~2 anode wells are generally set in a single storage tank; the soil resistivity increases and the potential of the tank floor is to the square. The distribution of potential is most significant to offset, current size and soil resistivity.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TE972

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