What effect does a high level of H2S in CO2 have on the quality of the alkali produced?
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This post was last edited by steinback on 2010-6-20 16:56. What changes can high H2S levels in CO2 cause in the quality of the alkali produced? Currently, the H2S content in CO2 is as high as 150 mg/M3. When this situation occurs in your workshop, will red alkali be produced? Will it still be alkaline? I also want to ask, what exactly causes the high iron content in soda ash? Do you use a lot of Na2S in your workshop?
How is H2S generated in your CO2 gas? With the current level of H2S, it would result in about 150 Kg per ton of alkali – how is that possible? Such a high level is by no means beneficial for the production system. The so-called red alkali arises when equipment corrosion causes some FE3+ ions to precipitate as FE(OH)3 within the soda-making tower; these particles mix with NaHCO3, causing the soda ash to turn colored. If too much Na2S is present in the system, FES does not dissolve easily and remains intact, resulting in gray alkali. Once this gray alkali enters the calcination furnace, FES transforms into FE2O3, which also causes the soda ash to become red in color
This post was last edited by yanshan86 on 2010-6-19 at 21:07. I have always had doubts regarding the amount of sulfur added. At our factory, this amount has been adjusted several times; at times it was added in every shift, and that amount was three times higher than it is now. Currently, sulfur is added once a day, at a rate of 0.125 kg per ton. If we follow what the original poster suggests, then the sulfur content in the CO2 would be the same as that resulting from adding sulfur to the system – so would it be possible to avoid adding sulfur altogether? ? Wouldn’t that save money?
Correction: The H2S content in the CO2 is as high as 150 mg/M3. The H2S in our CO2 gas comes from the previous purification stage. When we produce red alkali, we also produce gray alkali at the same time.
Reply to 4# steinback: If the strong alkali turns red, it indicates that no sulfur film has formed on your carbonization tower, resulting in severe corrosion and oxidation. You can control the oxygen content in the system; if it turns gray, it means the sulfur content is too high, meaning the sulfur film is too thick and tends to fall off. Whether it turns red or gray, in either case this leads to an excessive FE content in the final alkaline product
Reply to 3# yanshan86: Yes, using too much sodium sulfide is not beneficial either. In the ammonia absorption process, oxygen generally does not enter the system, and the calcium and magnesium ions in the brine can form double salts that cause scaling. The most severe corrosion occurs during the carbonization process, as the oxygen content in the gas stream at that stage is high, and there is intense gas erosion, especially above the gas-liquid interface, where the corrosion is even more severe. We once had a situation where the upper few layers of one of the carbonization towers were corroded to just 5 mm in thickness.
If CO2 contains H2S, how is H2S handled in the process? ? Or how to adjust this content so as to reduce the amount of vulcanization in subsequent processes; this way, costs can be lowered and product quality can also be controlled
What if it isn’t red or black, but still has high alkalinity along with iron emission?