The new catalyst stopped working after just 11 days of use!
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The conversion section of System I for sulfuric acid in our plant was completely replaced (S101) during a maintenance operation not long ago, and gas supply was resumed on the 6th. I received a report just now: a section of the System I conversion unit has stopped responding, with no temperature rise observed; as a result, it was necessary to increase the inlet temperature of the bed by 10 degrees! The aforementioned catalyst manufacturer is one of the larger domestic producers in this field; I visited them just before last Spring Festival.
What is the inlet temperature of the bed layer before temperature increase in the conversion section of your Sulfuric Acid I system? What are the SO2 and O2 concentrations in the conversion section?
Before temperature increase, it was 420 degrees, with large fluctuations in concentration, reaching up to 9% at its highest. It could also be an issue with the purification parameters; the levels of arsenic and fluoride after purification are definitely above the limits.
In a situation like yours, operating at 420 degrees for S101 is a bit low; it’s better to operate at 430 degrees. What is your loading height per section? What are the shape and size of the catalyst?
Under normal circumstances, the performance of newly introduced catalysts is slightly higher than the specified standards. It is a normal (usual) phenomenon.
Hehe, I’ve never heard of something like this happening before. There can’t be any increase in temperature at all, right? What will happen in the subsequent stages? You’ve already analyzed the most likely scenarios; I hope updates on the progress will be shared as soon as possible!
After installing a brand-new catalyst, was it sealed or exposed to other substances? Generally, an inlet temperature of 430–445°C is ideal. For domestic catalysts, it is necessary to analyze their composition.
Could it be that there was a problem during loading? What about the pressure and temperature at the back? Have the purification indicators had their components analyzed?
The new catalyst performed normally at the beginning of its operation, and the reasons are under investigation.
I think it might be catalyst poisoning; factors such as As, selenium, F, and moisture that cause the poisoning should be analyzed. Also, test the effective vanadium pentoxide of the catalyst.
I also think it might be catalyst poisoning, but it seems like nonsense, haha
The test results are in today, and the arsenic content in the flue gas at the fan outlet is as high as 2 g/Nm3!
It is essential to ensure high quality of the raw materials; the impurity content must not exceed acceptable levels, especially arsenic, as it can poison the catalysts, indicating that there are problems in the purification process!
It’s no easy task to control the raw material supply! It's already good enough to be able to buy the raw materials.
Since it is a new catalyst, even if the various purification parameters are not up to standard or are severely inadequate, the catalyst will not become unable to function as a result over an 11-day period. Therefore, I believe the issue is mainly due to improper operation. The S101 catalyst is a medium-temperature catalyst, with an operating temperature ranging from 425 to 600 degrees. In practical use, it is best to maintain an inlet temperature of 430–440 degrees. Could what happened in your plant be due to too low a temperature, such that flue gas was introduced for production before the catalyst reached its ignition temperature? Or is it because the sulfur dioxide concentration is low and the reaction temperature is not high, resulting in an inability to achieve thermal equilibrium?