| LYU Liushuai,GAO Luyang,DAN Tichun,HU Ningyin,XIAO Diaobing,CHEN Yinqiang.Effect of Polyacrylic Acid on Flow Accelerated Corrosion Behavior of Materials with Different Cr Content[J],53(16):139-150 |
| Effect of Polyacrylic Acid on Flow Accelerated Corrosion Behavior of Materials with Different Cr Content |
| Received:September 07, 2023 Revised:January 25, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.16.011 |
| KeyWord:PAA flow accelerated corrosion secondary circuit |
| Author | Institution |
| LYU Liushuai |
China Nuclear Power Operation Technology Corporation. LTD., Wuhan , China |
| GAO Luyang |
China Nuclear Power Operation Technology Corporation. LTD., Wuhan , China |
| DAN Tichun |
China Nuclear Power Operation Technology Corporation. LTD., Wuhan , China |
| HU Ningyin |
China Nuclear Power Operation Technology Corporation. LTD., Wuhan , China |
| XIAO Diaobing |
China Nuclear Power Operation Technology Corporation. LTD., Wuhan , China |
| CHEN Yinqiang |
China Nuclear Power Operation Technology Corporation. LTD., Wuhan , China |
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| Abstract: |
| During the operation of nuclear power plants, sludge deposits and fouling will form on the secondary side of the steam generator, which will affect the heat transfer of the steam generator and cause the thermal and hydraulic instability of the steam generator. In order to solve the thermal hydraulic instability caused by sludge deposition and scaling, chemical cleaning methods are mostly used in foreign countries to treat deposition and scaling in SG, and most of them are hydromechanical cleaning in China. Research has shown that polyacrylic acid (PAA) has a strong ability to disperse iron oxide and can effectively remove corrosion products on the secondary side of the steam generator, thereby improving the reliability of the steam generator. Although the synthesis research of domestic PAA is relatively mature, there is still no research on the effect of domestic PAA on flow accelerated corrosion. Flow accelerated corrosion (FAC) is the main mechanism for thinning of secondary circuit pipelines, resulting in thinning of pipeline wall thickness, and even causing pipeline failure and bursting. There have been many pipeline leakage and even rupture accidents in history, causing major human and economic losses, which directly affects the safe operation of nuclear power plants and the life safety of nuclear power workers. To ensure the safe and reliable use of domestic PAA in domestic nuclear power units, in this article, FAC performance research experiments were conducted to study the effect of PAA on alloy steel materials A106B, A335P22, 304 with different Cr content under high temperature, high pressure, and environmental conditions by adding PAA, so as to explore the effect of PAA on the flow accelerated corrosion performance of secondary circuit pipelines of domestic nuclear power units. Relying on the electric heating test bench, a flow-accelerated corrosion test loop was designed with a blank group without adding PAA and a test group with PAA, and 3 samples were set in each blank group and test group to study the difference in FAC corrosion behavior of test materials before and after dosing in high temperature and high pressure and flowing water environment. The sample was polished before the test, ultrasonic cleaning was carried out with absolute ethanol solution, and then dried and weighed. After the test, after rust removal with brush, ultrasonic cleaning was carried out with absolute ethanol solution to remove corrosion products, and the thinning rate was calculated by mass loss. The microscopic morphology of pipe surface corrosion was observed by scanning electron microscopy (SEM). And the influence of PAA on A106B, A335P22 and 304 materials with different Cr content was studied. The conclusion is as follows:1) At 220 ℃, 6.7 MPa, with the flow rate 4.68 m/s, when A106B, A335P22 and 304 stainless steel pipes are not added with PAA, the FAC corrosion rate is 0.112 0, 0.068 6, 0 mm/a, and the FAC corrosion rate is 0.095 6, 0.066 9, and 0 mm/a, respectively. 2) The addition of PAA with a concentration of 5 μg/kg-10 mg/kg has no obvious effect on the FAC corrosion rate and surface morphology of A106B, A335P22 and 304 stainless steel. It does not change the corrosion resistance grade of the material, that is, the addition of PAA has no obvious effect on the compatibility of these materials to accelerate the corrosion environment. 3) Due to the dispersion of PAA, the addition of PAA has a certain inhibitory effect on the FAC corrosion rate of carbon steel material A106B, but it has no obvious effect on A335P22, 304 stainless steel with high Cr content. 4) Before and after the addition of PAA, with the increase of Cr content, the trend of FAC corrosion rate is consistent and gradually decreases. It can be seen that the presence of Cr element can inhibit the FAC phenomenon. |
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