Who has experienced an excess of H2S due to an excess of NH3?

If excessive ammonia leads to an increase in hydrogen sulfide levels, immediately add some fresh methanol to the system to maintain normal operation, discharge some of the methanol, and then carry out regular discharges/additions to ensure that the methanol quality remains satisfactory!

Who has experienced something similar~! What was the situation like at that time~! What are the approximate values for each parameter? Hope to share it? As for the reasons and solutions, there were many before! Comrades who are not sure can take a look

We haven’t experienced it, but according to various sources, when the ammonia level in the system exceeds 5 mg/m3, it is possible for hydrogen sulfide levels to become too high!

I believe that if the ammonia level in the methanol solution is too high, ammonium sulfate is formed in the methanol solution in the hot zone; whereas in the methanol-poor solution, due to the low temperature at the top of the absorption tower, ammonium sulfate decomposes again, resulting in an excessive sulfur content in the purified gas exiting the scrubber tower.

First of all, I’m a bit puzzled by the fact that excessive ammonia in the system leads to excessive hydrogen sulfide in the purified gas. First: Generally speaking, ammonia affects the absorption efficiency of methanol washing; I’m not sure what the principle behind this effect is Is it \"a small amount of ammonia dissolved in methanol\"? It’s still ammonia dissolved in the water within the circulating methanol – so how could that affect the absorption of methanol? Then doesn’t it affect the absorption of carbon dioxide? Second: Regarding the decomposition of ammonium sulfide, what are the conditions for its decomposition? It’s a bit puzzling that ammonium sulfide did not decompose in the lower part of the regeneration tower or in the methanol collection tank, but instead decomposed at the lower temperatures in the washing tower. I can’t understand the concept of chemical equilibrium either. Third: It’s still the theory of sulfide decomposition; assuming that sulfides decompose more easily at low temperatures, then when hydrogen sulfide levels are too high, can ammonia be detected in the analysis of the purified gas? It’s also a basis for judgment. I’ve looked into many factors that affect the absorption in methanol washing processes; it’s mentioned in passing that ammonia has an impact, but there’s no theoretical basis for this, and I’ve also encountered no practical problems related to it. I hope everyone will continue to discuss this topic.

Friend “yangziwei” on the first floor of http://bbs.hcbbs.com/thread-399309-1-2.html mentioned that he has experienced situations where NH3 led to excessive H2S levels, and he also shared the methods for dealing with it! Why is it said that excessive NH3 levels can lead to excessive H2S levels: 1. The syngas requires a very low H2S content, and that is the standard set by our factory

“First: Generally speaking, ammonia affects the absorption efficiency of methanol washing; I’m not sure what the principle behind this effect is Is it \"a small amount of ammonia dissolved in methanol\"? It’s still ammonia dissolved in the water within the circulating methanol – so how could that affect the absorption of methanol? Then doesn’t it affect the absorption of carbon dioxide? ” I disagree with this; I think the presence of NH3 in methanol will not affect the system’s absorption, as absorption is a relatively independent process.

You didn’t understand my first statement; it was a rhetorical question, representing an opinion I disagree with, haha! ! What you said about the impact of chemical equilibrium makes some sense. I conducted an analysis once: when the hydrogen sulfide concentration control valve in the regeneration tower was not activated, the gas phase components in that tower were approximately 90% carbon dioxide, around 5% hydrogen sulfide, and about 3% nitrogen – those are the approximate figures. However, it is not impossible over time. However, our water separation tower discharges a large amount of substance that looks like “butter”; I believe it is sulfur ammonia. It mainly comes from methanol spraying. It’s a bit strange to have so much sulfamide under these conditions. If the original poster is interested, check out the conditions for sulfuramide decomposition, and then we can discuss it further.

Also, in solution, ammonium sulfide does not exist as crystals; instead, there is an equilibrium reaction: (NH4)2S = NH3 + 2H2S. So I think there’s no need to consider crystallization!