Corrosion structure issues in desulfurization pipelines
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The desulfurization pipelines in our plant have been in use since 2006, and leaks occur frequently. Crystalline substances accumulate inside the pipes, accounting for about 1/4 to 1/3 of the pipe’s volume. Despite being insulated, the pipes still leak often, which results in repeated shutdowns and restarts. Have similar problems occurred with the desulfurization pipelines in other companies? How did you handle it? Especially the crystallization issue inside the pipes.
There are many crystallizations in the pipeline; could the level of by-products be high? Lower temperatures may lead to crystallization. For pipeline leaks, one factor is whether the right material has been chosen; using seamless steel pipes will ensure no problems for 5-8 years. The material is fine; it depends then on the composition of your solution – areas where crystallization occurs may suffer severe corrosion.
The pipes replaced this time are seamless steel pipes, and some adjustments have also been made to the pipeline layout to try and prevent condensation from occurring under special conditions, which could lead to dew point corrosion. Hopefully it will work.
Pipe crystallization may be caused by the formation of ammonium salts. If the pipeline is thin and the distance is short, this section of the pipeline can be made into a jacket. If the pipeline is thick and the distance is long, multiple heating coils using 1.0 MPa steam can be used for that section of the pipeline, thereby preventing the formation of ammonium salts.
Ammonium salts? I think it’s sulfates; there’s also a mixture of dark green and green colors. It’s not possible to conduct an analysis at the moment, so further examination is needed. Based on the color, it might be heptahydrate sulfate along with other impurities.
I work in the power plant industry. I’m not sure what process is used in your desulfurization unit; if it’s the wet limestone-gypsum method, the slurry pipes are usually lined with rubber. Please provide information on the medium conditions, such as pH and CL levels
Yes, it’s necessary to specify exactly what desulfurization process is being used, as well as the material flowing within the pipelines, so that your question can be answered more effectively.
It’s the flue gas desulfurization in thermal power plants. The one that was just replaced today has already blocked half of the pipeline; sulfates also absorb moisture, and once condensation occurs, these pipelines are highly prone to corrosion, so our pipelines are essentially useless now. The pipeline is over 500 meters long in total, with some bends as well.