Why does the flue gas appear yellow after being treated to meet standards using the ozone method?
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I am using the ozone desulfurization method combined with single-alkali desulfurization here. Online monitoring of the flue gas shows that sulfur dioxide levels are between 2 and 5, nitrogen oxides between 10 and 40, and dust levels between 1 and 4. Why does the flue gas appear yellow during the day? I’m just starting to work with this area, and I would be grateful for any guidance from the experts.
This post was last edited by Yunxin Heyan on 2018-5-4 at 22:24. I have been consulting experts from various fields recently, and today I received an explanation from the process engineers at an ozone equipment manufacturer; it seems to be quite reliable. Let’s discuss this together: We believe that, aside from issues related to color perception or the direction of observation, the most likely cause is the high level of NO2 in the smoke, which leads to its yellowish color. As we all know, among various nitrogen oxides, only NO2 is red-brown in color (see the attached figure); whereas other substances present in flue gas are colorless and do not produce any pigments. Improvement plan: First, use a handheld meter to measure the NO2 content in the flue gas, and verify the measurement range and accuracy of the online monitor ； Second, increase the production of ozone to enhance its oxidizing capacity toward NO, thereby oxidizing the nitrogen element as much as possible to higher-valent N and O compounds, which facilitates their removal by the absorption solution ； Third, the alkalinity of the liquid in the desulfurization tank can be increased moderately to boost the absorption efficiency of the absorber tower ； And use maintenance to promptly check the condition of the absorption tower, to determine whether there are any faults with the spraying components ；