The sulfuric acid AN product produced through flue gas desulfurization is yellowish or whitish in color, and its crystals are too small – what could be the reason?
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Flue gas desulfurization in thermal power plants is carried out using ammonia water prepared from liquid ammonia; recently, the quality of the sulfuric acid AN produced has declined significantly. The appearance of the product is not that of a white crystal; it is yellow in color with a slight green tint. After analyzing the slurries in the absorption tower and concentration tower, both liquid phases were yellow-green in color, with a certain amount of sediment present. Ammonia water contains a small amount of impurities. No significant adjustments have been made to the flue gas desulfurization unit in terms of its process, and the liquid material inside the unit is yellow-green in color. In the current production of sulfuric acid, the product crystals are extremely small and have abnormal colors; sometimes no product can be obtained at all, and the slurry has to be discharged into an emergency tank. Gentlemen, could someone please explain this? How can this problem be solved from a production process perspective? Feel free to come and chat!
This post was last edited by *aojiaoya0546 on 2016-1-27 at 21:37. Regarding flue gas desulfurization, many refineries are also actively implementing such measures; everyone is welcome to discuss this topic.
This post was last edited by swj_014 on 2016-1-31 at 10:14. Hydrogen sulfide may be present in the smoke; it reacts to form elemental sulfur, which then creates thioesters that prevent crystallization. It is recommended to measure the composition of the flue gas
The liquid feed in the absorption and concentration stages has a pungent odor, and the product as well has an unpleasant smell. After the liquid slurry settles, the iron ion concentration in the upper clear layer is below 5 ug/ml, while the iron ion concentration in the sedimented material in the lower layer is very high, ranging from 300 to 500 ug/ml; thus, the iron content differs between the two layers. Could it be two different types of iron? ? ? ? ? ? The absorbed and concentrated liquid as well as the product have a yellow-green color. What is the reason for this yellow-green color?
Perhaps there are soluble iron salts of different valence states in the solution; solutions of iron salts with different valence states have different colors. The precipitate may contain iron sulfide. I think the solution will undergo various reactions, making the situation relatively complex; in contrast, changes in the composition of the smoke are more straightforward to observe.
The yellowish-green color only appeared in the past six months or so; in previous years, the colors of the materials within the system were normal, without any yellowish-green tint.
Were there any significant changes in the manufacturing process or raw materials before and after the change?
There are no changes to the process; only the flue gas denitration step has been added. In the original process, the flue gas did not undergo denitration, but now it passes through a denitration unit.