Total sulfur level in low-temperature methanol washing is excessive
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The total sulfur level in the low-temperature methanol washing process is above the specified limit, and it fluctuates from time to time; we use a five-tower low-temperature methanol washing system. The system is already filled with ammonia, and equipment issues have been ruled out; I seek advice from those with more experience.
Let’s analyze it to see if it’s caused by the organic sulfur content in the previous section
I even changed the medium just for this vaporization
Analyze the sulfur and carbon dioxide in the gas phase of the lean methanol tank to examine their conditions
Could you be more specific about in what medium the total sulfur level is excessive? Purified gas? Exhaust fumes? Poor methanol?
The sulfur content in lean methanol is not high either
The total sulfur content in the gas purified by low-temperature methanol washing is above the specified limit
If the analysis of the regenerated lean solution shows normal levels, it is still necessary to check the ammonia content in the solution. Excess ammonia can lead to the formation of ammonium sulfide at the bottom of the regeneration tower, which then decomposes at the top of the absorption tower to release H2S. If everything is normal, pay attention to whether there are any dark brown crystals (FeS or iron carbonyl) in the filters at the inlet of the methanol washing pumps and in the precision filters. Such substances are flammable. It’s possible that high water content during the initial startup phase or during gas introduction caused corrosion; another possibility is that the carbon steel filters were exposed to air for too long during maintenance and were not thoroughly cleaned, resulting in the formation of iron carbonyl. We have encountered this issue before, and to resolve it completely, it is necessary to shut down the system, wash it thoroughly with water, and use nitrogen purging to eliminate all traces of such substances. To maintain control during operation, it is essential to pay close attention to regulating the water content; sodium hydroxide can be added in appropriate amounts to the methanol-water separation tower (although this is rarely used in modern designs). Additionally, when performing maintenance on areas where carbon steel equipment is used extensively, care must be taken to prevent exposure to air.
What is the methanol deficiency level? Do the various components meet the standards?
It’s unlikely that the total sulfur level will exceed the limit in general. Could increasing the amount of rich methanol sprayed in the desulfurization section also cause the level to exceed the limit? Spray a bit more
What is the methanol deficiency level? Do the various components meet the standards? All have met the standards