The problem of discoloration to green after sampling of the lean solution
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I would like to ask the experts: in the regeneration unit of our plant’s desulfurization system, the lean liquid turns green within a few seconds after sampling. I looked up some information online because of the formation of ferrous iron, and there was a problem with the regeneration unit. In our company, the current hydrogen sulfide content in the lean solution is 0.02%, and the iron content is less than 1 ppm. Are these values normal? Are there any clear guidelines or experience shares? Thank you all very much!
Hello, based on the information you provided, the green color of the lean solution is likely indeed due to the formation of ferrous iron in it. Generally speaking, a hydrogen sulfide content of 0.02% is considered a relatively low level, and an iron content of less than 1 ppm is also quite low. These values are normal within the usual operating range. However, even a very small amount of iron can still affect the color of the lean solution, especially under certain conditions where iron ions are prone to oxidation. It is recommended to check whether oxygen has penetrated the system, or any other factors that could cause oxidation of iron sulfide. At the same time, it is also possible to consider inspecting and maintaining the regeneration system to ensure that no other underlying issues are causing this phenomenon. I hope this information will be helpful to you. .
The lean solution of the desulfurization liquid also contains high concentrations of sulfides. When a sample is taken, it comes into contact with air, and the sulfides undergo incomplete oxidation to form polysulfides. Depending on their molecular weight, these polysulfides appear in shades ranging from pale yellow to pale gray-green; this is not due to the presence of metal ions.