Ammonium sulfate solution corrosion

There should be grain erosion; simple corrosion would not be that severe.

What device is it? Is it a pipeline or a heat exchanger? If it is a pipeline, fiberglass-reinforced plastic pipelines are recommended ； If it is a heat exchanger, it is recommended to use a graphite heat exchanger ； If it is an evaporation concentration unit, it is recommended to use a graphite evaporation concentration unit (as a complete set).

In the exhaust gas washing system of sulfuric acid plants, carbon steel lined with rubber is used for ammonium sulfate solution equipment, while fiberglass-reinforced plastic is commonly used for pipes.

It’s better to conduct a comprehensive analysis, including tests for fluoride ions, chloride ions, pH value, etc. Once the analysis results are available, the true cause will become clear.

Corrosion of the saturator body or pipeline corrosion

The situation you are in is the same as ours. Ammonium sulfate solution can dissolve everything; our entire exhaust gas desulfurization system is made of 316L and 316Ti materials (including the exhaust chimneys, which are also made of explosive composite panels). This problem has plagued us for 2 years. During that period, the exhaust fans, flue gas ducts, damper doors, quench towers, and spray pipes were completely corroded. We were forced to replace both ammonium sulfate and the materials that came into contact with the flue gas coming from upstream with 904L material, but found that this only delayed corrosion, reducing it from 1.2 mm per month to 0.1 mm per month. No one wants to discuss the entire system anymore; everyone wants to start over from scratch. While repairing it, we came across a piece of information while reading the operation manual, which ultimately saved this device. “The pH of the ammonium sulfate solution should not be less than 5; they insisted on continuing production, believing that this was not the main cause, and maintained that they had no way to lower the pH value of the system. The issue was reported to the senior management, who pressured the production team to find a solution; as a result, the pH level of ammonium sulfate in the system was raised to pH 5. The situation really improved, and all the equipment has been in use for 4 years since those improvements were made, with no signs of corrosion anymore. Sometimes solving a problem is that simple; if you can’t see it, you’ll never be able to improve it. When I see PH3 that you mentioned, it’s as if I’m seeing myself from 4 years ago.

It’s written very professionally. I’ll learn from you!*