本文關(guān)鍵詞：供水系統(tǒng)鑄鐵管材的腐蝕行為及影響因素研究　出處：《哈爾濱工業(yè)大學(xué)》2014年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 供水管網(wǎng) 微生物腐蝕 生物膜 鑄鐵管材

【摘要】：本課題以保證供水管網(wǎng)的水質(zhì)安全為目的,通過靜態(tài)實驗和動態(tài)實驗較為全面地探討了鑄鐵管材的腐蝕機(jī)理及影響因素。從管段中提取生長環(huán)及污泥,經(jīng)分離提純得到硫酸鹽還原菌和鐵細(xì)菌菌株,以相應(yīng)的培養(yǎng)基培育菌株作為腐蝕介質(zhì),監(jiān)測微生物的生長代謝對生長環(huán)境的影響。采用電化學(xué)方法和表面分析技術(shù)研究硫酸鹽還原菌和鐵細(xì)菌對金屬管道腐蝕的影響,探討微生物存在時,陽極金屬的活性溶解和生物膜下點蝕的萌發(fā)和生長發(fā)展。通過動態(tài)實驗?zāi)M水流對管壁的沖刷作用,研究不同流速、流態(tài)下管材腐蝕行為的變化。實驗發(fā)現(xiàn),管網(wǎng)中微生物主要存在于管道內(nèi)壁,而金屬表面的粗糙程度與細(xì)菌的黏附和生物膜的形成等因素有關(guān),因此細(xì)菌總數(shù)、鐵細(xì)菌和SRB數(shù)量在鑄鐵管材上都呈現(xiàn)出最大值(分別為5.3×107 cfu/cm2、2.5×105 cfu/cm2、184cfu/cm2,t=45d),說明管材的選擇對水中細(xì)菌總數(shù)和生長環(huán)的形成是至關(guān)重要的。硫酸鹽還原菌可使鑄鐵管材發(fā)生點蝕現(xiàn)象。但相對于無菌水,腐蝕產(chǎn)物層的結(jié)構(gòu)更加多樣復(fù)雜,呈現(xiàn)不均勻性。本文針對供水管網(wǎng)的運行情況特點,揭示了水流速度和與鑄鐵管材腐蝕速率的關(guān)系。腐蝕速率與主體水流速線性相關(guān),流速的增加,加快了水中腐蝕性物質(zhì)的傳輸速率和電荷轉(zhuǎn)移過程,從而促進(jìn)鑄鐵的腐蝕進(jìn)程。動態(tài)實驗中維持一定的水力停留時間可導(dǎo)致鑄鐵管材的腐蝕速率增大,說明主體水由靜態(tài)-動態(tài)或動態(tài)-靜態(tài)的變化促進(jìn)了鑄鐵管材的腐蝕過程。流速的變化加快了使腐蝕性物質(zhì)的傳輸和腐蝕進(jìn)程,從而使管材的腐蝕速率大于主體水流速恒定的狀態(tài)。此外,鑄鐵管材的腐蝕與水質(zhì)條件變化密切相關(guān)。隨著腐蝕速率的增加,水中濁度和色度明顯增加,說明鑄鐵管材腐蝕是“有色水”的產(chǎn)生的主要原因;此外,腐蝕還可能導(dǎo)致鑄鐵管材向主體水中釋放鐵離子,使水中Fe2+濃度和總鐵含量增大,影響供水水質(zhì)。本研究建立了水中氯濃度與鑄鐵管材腐蝕速率的變化關(guān)系。Cl-可使鑄鐵表面表面活性點增多,吸附的Cl-含量增大,而電荷轉(zhuǎn)移電阻Rct降低至6307×103Ω·cm2(CCl-=2.0mg/L),從而加速了鐵的陽極活性溶解過程,使鑄鐵管材的腐蝕速率增大。通過SEM觀察到鑄鐵表面存在明顯的點蝕坑,且蝕孔深度與鑄鐵表面的平均粗糙度隨時間的增加而增大,表明水中氯離子的存在可導(dǎo)致鑄鐵管材的腐蝕過程以點蝕的形式向管壁內(nèi)部發(fā)展,對管材的破壞性極大。研究表明水中氯離子作用下生成的腐蝕產(chǎn)物主要為Fe2O3、Fe3O4和α-Fe OOH和γ-Fe OOH,其結(jié)構(gòu)疏松多孔。氯離子存在時,易形成穩(wěn)定性較差的β-Fe OOH,暴露于空氣中轉(zhuǎn)化為α-Fe OOH和γ-Fe OOH,因此在XRD分析中并未檢測到此相。但β-Fe OOH大量存在于腐蝕產(chǎn)物層內(nèi)部,其相針之間的間隙較大,可以使水分存留其中,為點蝕的發(fā)生創(chuàng)造有利條件。與α-Fe OOH相比,其結(jié)構(gòu)比較疏松,不易于形成致密的鈍化層而抑制管道的腐蝕發(fā)生,而Cl-可能阻止腐蝕產(chǎn)物向較穩(wěn)定的α-Fe OOH轉(zhuǎn)變,抑制管材表面鈍化層的形成。
[Abstract]:This issue in order to ensure the quality and safety of the water supply network for the purpose of through static and dynamic experiments of a more comprehensive study on the factors of corrosion mechanism of cast iron pipe and influence. The extraction of growth ring and sludge from the pipe, after separation and purification by sulfate reducing bacteria and iron bacteria strains, with the corresponding culture medium cultivation strains as corrosion medium that affected the growth and metabolism of microorganisms on the growth environment monitoring. Affected by electrochemical methods and surface analysis techniques of sulfate reducing bacteria and iron bacteria on the corrosion of metal pipes, to investigate the microbial existence, pitting germination and growth development of anode metal dissolution and biofilm. Through the experiment of simulating water flow to scour pipe on the wall, different flow rate, change of corrosion behavior of tubing flow. It was found that the main microbial network in the inner wall of the pipeline, and the metal surface The roughness and bacterial adhesion and biofilm formation and other factors, so the number of total bacteria, iron bacteria and SRB in the cast iron pipe takes on a maximum value (5.3 x 107 cfu/cm2,2.5 x 105 cfu/cm2184cfu/cm2, t=45d), description of material selection for the total number of bacteria in water and growth is essential for the formation of the ring the sulfate reducing bacteria. The cast iron pipe pitting phenomenon. But compared with sterile water, the structure of the corrosion product layer is more complex, appear uneven. The operation according to the characteristics of the water supply network reveals the flow velocity and rate of cast iron pipe corrosion. The corrosion rate and the main flow velocity, linear correlation, velocity the increase of the transmission rate and accelerate the charge transfer process of corrosive substances in water, so as to promote the process of iron corrosion. Maintain a certain hydraulic residence time in dynamic experiment The corrosion rate of cast iron pipe can lead to the increase of main water change from static and dynamic - static or dynamic promoted the corrosion process of cast iron pipe. The change of flow rate to speed up the transmission and corrosion process of corrosive substances, so that the corrosion rate is greater than the main flow velocity constant. In addition, the change of corrosion and the water quality conditions of cast iron pipe is closely related. With the increase of corrosion rate, color and turbidity of water increased significantly, that cast iron pipe corrosion is the main reason of colored water produced; in addition, may also lead to corrosion of cast iron pipe release iron to the main body of water, the concentration of Fe2+ in water and the total iron content increases, affecting water quality. This study established the.Cl- relationship of chloride concentration and corrosion rate of cast iron pipe can make the surface of cast iron surface active point increase, increasing the content of Cl- adsorption, and charge transfer Shift resistor Rct is reduced to 6307 x 103. Cm2 (CCl-=2.0mg/L), which accelerated the anodic dissolution process of iron, the corrosion rate of cast iron pipe increases. Observed by SEM has obvious pitting surface of cast iron and cast iron, pitting depth and surface roughness average time increases, that the presence of chloride ions in the water can lead to corrosion of cast iron pipe to pipe wall to form the internal development of pitting, damage to pipe greatly. The results show that the corrosion products under the effect of chloride ions in the water are mainly Fe2O3, Fe3O4 and -Fe OOH -Fe OOH alpha and gamma, the porous structure. The presence of chloride ions. Easy to form the poor stability of beta -Fe OOH, exposed to the air into a -Fe OOH and gamma -Fe OOH, so the XRD analysis did not detect this phase. But there are a lot of OOH beta -Fe in the corrosion product layer, a gap between the needle Big, can make the water retention, create favorable conditions for the occurrence of pitting. Compared with a -Fe OOH, the structure is loose, corrosion is not easy to form a compact passivation layer and inhibit the pipeline, while the Cl- may prevent the corrosion product transition to more stable alpha -Fe OOH, inhibit the formation of tube surface passivation layer.

【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU991.38

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