Regarding hydrogen sulfide at the variable degassing inlet

What is the total sulfur content at the medium-voltage inlet? If the total sulfur content at the inlet is high, it will also increase the hydrogen sulfide level at the medium and low temperature outlets.

It is also possible that there was desulfurization during the initial stage of operation of the low-temperature catalyst, and now the system is lacking in sulfur

OP! When the hydrogen sulfide concentration at the inlet of the B303Q catalyst exceeds 150 mg, counter-sulfidation can basically be disregarded! And this low-temperature conversion catalyst has been in use for almost three years already!

There are abnormalities in two aspects: one is the high level at the intermediate conversion outlet, and the other is the low level at the conversion and desulfurization inlet; this is likely caused by catalyst sulfidation and desulfidation. 1. Inside the medium-temperature converter: Fe3O4 + 3H2S + H2 = 3FeS + 4H2O. After checking, the equilibrium concentration of H2S at 450 degrees is 0.384 g/m3; if sulfidation had occurred in the medium-temperature catalyst earlier, then the addition of sulfur now is consistent with the data analyzed by the original poster. 2. The low-temperature converter has a strong capacity to convert organic sulfur; it can transform 98% of the organic sulfur into H2S. Currently, the level of H2S is lower than that before import, which suggests that sulfidation has occurred in the low-temperature converter – previously, there might have been desulfidation in this catalyst. This post was last edited by *aoye613 on 2009-3-9 21:31]

This indicates that your low-voltage side has already experienced desulfurization prior to this. Therefore, the reason for the significant difference between these two sets of data is normal; such a phenomenon is considered normal as well.

I think it is the result of organic sulfur being converted into inorganic sulfur in the medium-speed furnace

Judging from your mid-change inlet, it can be estimated that the organic sulfur level is likely to be high – at least 300. The reason for this lies in that factor

I’m not very familiar with the details of the analysis; I only know that the process gas from gasification, after undergoing conversion, has almost all of its organic sulfur converted into inorganic H2S. Are your analytical doubts related to this?

1. It is likely that during the previous production process, the hydrogen sulfide level (or sulfur content) at the inlet of the converter was low; now that the sulfur compound content at the inlet has increased, the low-temperature conversion catalyst has been subjected to a sulfidation process during production； 2. Or, too much steam was added to the conversion system during the previous production process, which caused partial desulfurization of some low-temperature conversion catalysts; now the amount of steam added has been reduced, and the sulfidation process is being carried out during production ； 3. Either the temperature control during the previous low-temperature transformation step was too high, resulting in partial desulfurization; now the temperature control has been reduced. ——In short, what the original poster described is the vulcanization process during production, which is a positive phenomenon for low-temperature catalysts. ——In fact, there are not only cases where hydrogen sulfide at the outlet of the low-temperature converter decreases, but also situations where the sulfur content at the outlet increases; during the production process with low-temperature catalysts, it is a process of sulfidation and desulfidation.

An expert from Hubei Institute spoke openly at a national conference on gas purification, saying that the anti-sulfurization data published previously were the results of calculations, and the basis for those calculations was incorrect. There are 10 inactivation factors, with the anti-sulfidation reaction placed in position 11.

1 The medium-activity catalyst becomes saturated with sulfur and begins to release sulfur, or it can be understood as reacting very little with sulfur. Or the sulfur content in the reformer gas inlet is high. 2 The low-temperature catalyst begins to absorb sulfur, which is a good thing for low-temperature operations. It is estimated that there was sulfur-rejection phenomena in the early stage, or sulfidation has not taken place for a long time, resulting in a sulfur deficiency. It can be considered that vulcanization is needed for this year’s major overhaul. Good catalysts for low-temperature applications can last for over 10 years, so regular maintenance is very important. Personal opinion, for reference only. This post was last edited by zhuoyue on 2009-2-17 21:25.]

The high hydrogen sulfide level at the medium-pressure outlet may be due to the conversion of organic sulfur to inorganic sulfur at high temperatures, while the low hydrogen sulfide level at the low-pressure outlet could be caused by a sulfidation reaction of the catalyst.

It’s not a question about this! Our hydrogen sulfide level at the medium-pressure inlet is over 280. The hydrogen sulfide from cobalt-molybdenum exports is around 360. They are all relatively high, mainly due to the issues of semi-dehydration and complete dehydration. My question is: since the cobalt-molybdenum export gas passes through a hot water tower, could part of the hydrogen sulfide be absorbed by the hot water? This post was last edited by wulashan on 2009-2-18 20:54]

1. Prior to this, anti-sulfidation occurs; when the sulfur level is high, the sulfidation reaction takes place. 2. Previously, the sulfur content was lower during operation compared to this time; when the sulfur level was high, the catalyst began to absorb sulfur (the catalyst has an adsorptive effect on sulfur), and when the sulfur level was low, the catalyst started to release sulfur. 3. Some of the hot water was washed away by the hot water tower. It can be determined by taking samples for analysis at the low-variation outlet. 4. Problems arising from the analysis.

The process flow may be: saturated tower – medium pressure conversion – hot water tower – pressure swing dehydration. It is very likely due to the saturated hot water tower; because of the hot water circulation, there are differences in pressure and gas composition between semi-water gas and shift gas, resulting in a gas \"short circuit\" that bypasses the shift reactor. Hydrogen sulfide dissolves in the hot water tower and is released in the saturated tower. Other evidence includes: the oxygen content at the outlet of the hot water tower is higher than that at the outlet of the shift converter. There are other reasons for this situation in the original poster’s case; for example, an excessive level of organic sulfur in semi-water gas contributes to this noticeable phenomenon ； The pH of the hot water was not properly controlled, resulting in an excessive solubility of H2S, among other issues. Feel free to continue the discussion.

When converting the feedstock, it is necessary to ensure that the sulfur content remains within a certain range – it cannot be too high nor too low. Medium-sized nitrogen fertilizer plants use medium-pressure desulfurization processes before carbon removal in order to protect the desulfurization agents. It can also be seen from the relevant parameters that the sulfur content in the feedstock after conversion is lower than that before conversion, as organic sulfur is not removed during the desulfurization process and is instead converted into inorganic sulfur

I agree with the view from floor 16; it’s likely that the pH level of the hot water in the hot water tower is too high, which leads to excessive dissolution of H2S, resulting in a low H2S level at the outlet of the conversion unit

Many plants add ammonia to the hot water towers to adjust the pH of the water; this addition may be related to the alkaline solution’s ability to absorb hydrogen sulfide.