Method for simultaneous analysis of hydrogen sulfide (H2S) and sulfur dioxide (SO2) in sulfur recovery
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Method for simultaneous analysis of high-concentration (% content) hydrogen sulfide (H2S) and sulfur dioxide (SO2) in sulfur recovery units. For sulfur recovery units, the accuracy of H2S and SO2 analysis is directly related to the long-term stable operation of the unit, as well as the conversion rate of H2S and the yield of sulfur. Analysis is the eye that oversees the operation of a device. I posted this earlier in the sulfur section; to enable more people to understand this method, I am posting it here in the analysis section. I hope more sea friends will communicate, discuss, and share their valuable opinions! Our method: A gas chromatograph with a TCD detector and a GDX-303 packing column (diameter 3 mm, length 2 m) is used; the volume of the quantitation tube can be determined as needed. Desiccant CaCl2 particles. Once, at a factory, I met someone in charge of analysis who said that chromatography manufacturers do not allow H2S and SO2 to be injected simultaneously, which surprised me because we have always injected them together without any problems so far. After a detailed analysis, the following possible issues were identified: 1. Ordinary factories may use capillary chromatography columns with a small inner diameter, which are prone to clogging ； 2. The chromatography manufacturers warn that a reaction may occur, but in reality, sulfur element is produced only when H2S, SO2, and water are present together ； 3. Before sampling, the analyst did not dry the gas, or the degree of gas drying was insufficient. Advantages of our method: 1. It uses a packed column with a large inner diameter, making it less prone to clogging ； 2. The gas is thoroughly dried, and neutral desiccants are used that do not react with H2S or SO2 ； 3. The temperature control in the column box is relatively low (50–80°C); even if a reaction occurs, its rate is low, resulting in an extremely small amount of elemental S being produced ； 4. Even if clogging does occur, it is sufficient to raise the column temperature by 30–50°C above the dew point of elemental S (by aging the chromatography column separately); the treatment method is very simple. Note: Since both H2S and SO2 analyzed in the factory are at constant levels (several thousand ppmV to percentage levels), a packed column along with a TCD detector is more than sufficient for analysis; domestic instruments (such as Beifen Rayleigh, Fuli, Lunan, etc.) are quite suitable for this purpose. I’d like to share some experience; I hope it will be helpful to everyone!
This can’t be called your original work. Before the adoption of spectroscopic analysis, this method was already used for the ratio analysis of sulfur in three major on-line chromatography systems, and Fluid Data Corporation also had specialized sampling and preprocessing equipment to work alongside these on-line chromatographs. Even with laboratory chromatographic analysis, there are specific operational requirements for sampling, sample transfer, and injection.
Speaking of which, it’s not really original; it should have been discussed already. However, it seems that this method is not widely used in sulfur recovery units, especially in situations where both H2S and SO2 concentrations are high. (If it’s widely adopted, then perhaps I’m just uninformed :L)
Is the poster someone who works on sulfur recovery systems? Most of the posts you’ve shared seem to be related to sulfur
We are engaged in research on sulfur recovery catalysts, and we also have some knowledge of the related processes.
"But in reality, sulfur element is formed only when H2S, SO2, and water are present together. If I remember correctly, the reaction between H2S and SO2 can occur without the need for water!
A sulfur ratio meter, an analyzer typically designed for Claus units
We have conducted related experiments before, and the results showed that a reaction occurs only in the presence of water. However, it must be ensured that there is absolutely no water at all, not even in the feed gas or the pipelines; even saturated water in the air can cause the reaction to occur. Therefore, we purged the device for a long time before introducing the feed gas for the reaction. If anyone is conducting experimental research, they can repeat my experimental results to see if they match.
The accurate analysis data from the analysis laboratory can be used to calibrate the comparator, thereby achieving the best results. After all, the ratio meters on industrial installations can sometimes be inaccurate as well.
This post was last edited by qugd on 2018-12-7 at 19:06. You said that hydrogen sulfide and sulfur dioxide require water in order to react to form elemental sulfur – do you have any evidence for this? Such as the reaction pathway or mechanism? What follows, “But it is necessary to ensure that there is absolutely no water at all, not even in the feed gas or in the pipes; even saturated water in the air can cause the reaction to occur.” ” What does this sentence mean? Does the above reaction require water, or does it not need water to take place? Also, if water is required for this process, then how can natural sulfur form in some active volcanic craters in Africa, where no water is involved, yet it can still be formed from sulfur dioxide and hydrogen sulfide? In some gas pipelines with high hydrogen sulfide concentrations, the environment is essentially free of water; however, there is a small amount of sulfur dioxide present, and elemental sulfur also precipitates. How can this phenomenon be explained? This desulfurization reaction can produce water on its own; it is not water that triggers this reaction. Rather, once water is formed as a result of this reaction, the presence of water in the system acts as a medium that facilitates the reaction, as sulfur dioxide and hydrogen sulfide can dissolve in water, thereby increasing the rate of subsequent reactions. This sulfur precipitation reaction becomes even more pronounced, especially when the temperature drops below the dew point of water in the system.