| ZHAO Zhong-xian,LI Wen-ge,ZHAO Yuan-tao,WANG Shuang-xi,BAI Yu-feng,WU Xin-feng,JIANG Tao.Corrosion Mechanism Analysis of Parts of Coal Storage Bunker in a Thermal Power Plant along the Coast[J],49(4):332-338 |
| Corrosion Mechanism Analysis of Parts of Coal Storage Bunker in a Thermal Power Plant along the Coast |
| Received:October 25, 2019 Revised:April 20, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2020.04.039 |
| KeyWord:coal storage bunker products mechanism pulverized coal oxygen corrosion oxygen concentration |
| Author | Institution |
| ZHAO Zhong-xian |
1.School of Merchant Marine Engineering, Shanghai Maritime University, Shanghai , China |
| LI Wen-ge |
1.School of Merchant Marine Engineering, Shanghai Maritime University, Shanghai , China |
| ZHAO Yuan-tao |
1.School of Merchant Marine Engineering, Shanghai Maritime University, Shanghai , China |
| WANG Shuang-xi |
2.School of Engineering, Shantou University, Shantou , China |
| BAI Yu-feng |
3.Haimen Power Plant, Huaneng Power International, Inc, Shantou , China |
| WU Xin-feng |
1.School of Merchant Marine Engineering, Shanghai Maritime University, Shanghai , China |
| JIANG Tao |
1.School of Merchant Marine Engineering, Shanghai Maritime University, Shanghai , China |
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| Abstract: |
| This work aims to investigate the corrosion mechanism of coal storage bunker parts in a thermal power plant. The study focuses on the analysis of corrosion mechanisms and causes on the coal storage bunker of power plant situated in coastal environment. The corrosion morphologies and the extent of corrosion products distribution on the surface and internal layers of the parts were systematically characterized by scanning electron microscopy (SEM). The phases and composition of the corrosion products were analyzed by the energy dispersed X-ray spectrum (EDS) and X-ray diffraction (XRD). The corrosion mechanism of parts were extensively discussed. It was noted that the mode of corrosion was localized corrosion, which severely attacked the working parts and structural materials on the coal storage bunker. The thickness of the corrosion area was about 3.82 mm. The corrosion morphology was heterogenous in nature with surface layer appearing rust brown while the internal layers had loose gray coloration. Aggregation of spherical and filamentous or cotton like rust alternated between outer and internal layers. The O and Fe were the main ingredient elements of the corrosion products. The main phase constituents of the brown rust, filamentous or cotton-like, gray-black substances and the needle-like substance were Fe2O3, a-FeOOH, Fe3O4 and g-FeOOH, respectively. Whereas, the globular substance consisted of a relatively high content of C, Si, Al, Ca, Mg and the main component was SiO2. which was caused by the pulverized coal particles. The corrosion mechanism of the parts was a complex reaction between various factors. At the initial stage of corrosion, the oxygen-absorbing corrosion reaction happened between the anode of Fe and the cathode of O2, and the following dehydration led to the production of the Fe2O3. However, due to lack of O2 in internal and bottom of the parts the corrosion products of Fe3O4 appeared as oxygen concentration cell corrosion. Thus, the bottom products were mainly the mixture of Fe3O4 and Fe2O3. Acidic gases such as CO2 and SO2 produced by pulverized coal particles and coal combustion created the conducive environment for the rapid corrosion. In these severe corrosive environments, failures of the parts like perforation could happen due to the pitting corrosion, which needed to be minimized by effective protective measures. |
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