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| Corrosion Mechanism and Protection of Sulfur Recovery Unit |
| Received:October 05, 2020 Revised:October 14, 2020 |
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| DOI：10.7643/issn.1672-9242.2020.11.004 |
| KeyWord:sulfur recovery corrosion protection corrosion mechanism electrochemical corrosion |
| Author | Institution |
| YUAN Hui |
Petro China Sichuan Petrochemical Co. Ltd., Chengdu , China |
| WANG Hui-qiang |
Petro China Sichuan Petrochemical Co. Ltd., Chengdu , China |
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| Abstract: |
| The work aims to study the corrosion mechanism of the sulfur recovery device in detail. Several corrosion types such as NH4HS scale corrosion, CO2-H2O corrosion, H2S-H2O corrosion, H2SO4/H2SO3 corrosion and high temperature sulfur corrosion were studied to provide corresponding theoretical basis for preventing equipment pipeline corrosion. Typical cases such as liquid sulfur and pipeline corrosion, high temperature blending valve corrosion, valve corrosion and ignition gun corrosion were analyzed in detail. The energy spectrum (EDS) analysis of the on-site damaged pipeline showed that the main corrosion products such as oxides, carbon compounds and sulfur compounds of the liquid sulfur interface caused breakage of the low-pressure steam pipe of the liquid sulfur pool, corrosion breakage of the heat tracing pipe and corrosion of the pump casing. The corrosion product reacted with water in the liquid sulfur pool, generating a variety of acids (sulfuric acid, sulfurous acid, etc.) and causing corrosion. As the liquid level gradually rose, the corrosion range continued to rise and expand. Due to the high temperature blending valve core is basically in a high temperature environment of 800~1000 ℃, a large amount of elemental sulfur, sulfur dioxide, hydrogen sulfide and the organic sulfur substance form a high-speed airflow in the high-temperature environment, and the equipment is washed by the high-speed airflow, causing serious corrosion to the equipment. At the same time, NH4HS crystallizes in the valve or ignition gun, and it is likely to deposit on the parts with lower flow rate, which will not only reduce the equipment function, but also cause corrosion under electrochemical scale. By analyzing the process principle, corrosion mechanism and corrosion status of the sulfur recovery device, combined with specific case analysis, corresponding protective measures are proposed. |
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