I have two chain burners here, and the flue gas from one of them is blue. Does anyone among you know what could be causing this?
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Our company has two chain boilers; one of them emits blue-colored flue gas. Denitration is carried out using SNCR, desulfurization is done via the double-alkali method, and bag filtering is used for dust removal. We tried turning off the denitration and desulfurization systems, but the flue gas still remained blue. Both boilers use the same type of coal. Does anyone know what could be the reason?
The bluish color of boiler flue gas is caused by the presence of sulfur trioxide in it. When the concentration of sulfur trioxide in the flue gas exceeds 30 ppm, Rayleigh scattering occurs on the side facing the sunlight, resulting in a blue appearance.
I think sulfur trioxide is the most likely cause, as the oxygen content in this furnace is relatively high. Some people say it’s due to coal tar and carbon monoxide, resulting from incomplete combustion, but the other furnace also has more or less the same problem.