Corrosion protection during the long-term shutdown of sulfur recovery units
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The sulfur recovery unit is shut down for maintenance, and the shutdown period is relatively long. During the previous shutdown of this sulfur plant, nitrogen protection was applied in accordance with the procedures, but severe equipment corrosion was detected during the maintenance period. We lack experience in terms of corrosion protection for equipment that is kept in standby mode due to the long-term shutdown of sulfur recovery units; we would appreciate it if you could provide some diagnosis and good suggestions
Short-term shutdowns can be protected with nitrogen, but for long-term shutdowns, the equipment is likely to be damaged.
The natural gas purification plant we built in Dazhou features anti-corrosion measures for humid hydrogen sulfide environments, and its performance remains excellent after ten years – for your reference!
What are some good solutions?
Just apply an anti-corrosion coating directly. It is simple to construct and has low costs.
Rinse thoroughly with plenty of clean water, then dry with steam; after the moisture has evaporated, protect it with nitrogen
Should the pipeline be steamed first, and then protected with nitrogen?
After a long period of time, the material should be removed for steaming, inspected, cleaned thoroughly, then sealed and purged with nitrogen as a protective measure
(1) Inadequate purging during shutdown; no inspections were carried out after shutdown, especially in critical areas such as equipment and pipelines with high concentrations of hydrogen sulfide, hydrogen sulfide burners, sulfur condensers, absorption towers, regeneration towers, amine-rich liquid pipelines, burners in exhaust gas incinerators, and other such critical components. (2) Incomplete nitrogen filling, nitrogen leakage, and failure to follow the requirements for nitrogen filling and maintenance.
Different parts are protected using different processes; the sulfur recovery section requires thorough purging with sulfur followed by protection under a slight positive nitrogen pressure； To prevent condensate water from corroding the heat exchange tubes on the outer wall of the steam drum tubes in exhaust gas incinerators, measures such as thermal protection and filling the furnace chamber with nitrogen for drying can be employed ； The exhaust gas quench water system must be drained and purged before being filled with nitrogen ； The amine solution system can be shut down only after it has passed regeneration testing. In short, prevent oxygen from entering the system to reduce the levels of hydrogen sulfide and sulfides within it; when the system is shut down, sulfur-containing substances can be oxidized by air to form sulfuric acid, thereby accelerating corrosion.