Sulfate additives are commonly used to reduce the amount of alkali chlorides in the flue gas of waste boiler.
Alkali chlorides will exist both in gas phase and in solid phase, according to the temperature distribution in the boiler pass. And both phases will be sulfated.
Is there any quantitative research about the extent of sulfation of alkali chlorides with respect to the phase? That is, which phase of alkali chlorides reacts with SO3 or SO2 dominantly, and how much?
I have read couples of representative researcher's works in this area such as Boonsongsup, Fielder, Iisa, and so on, but it is still confusing.
Thank you very much.
I teach the course on air pollution control (APC) technologies at Yale University and for removal of SO2 and SO3 from the flue gases, I discuss the use of CaO (calcium oxide) or calcium hydroxide Ca(OH)2 to convert SO2 & SO3 to CaSO3 and CaSO4 (both are in solid state). Coal-fired power plants use CaO or Ca(OH)2 as sorbents to first produce CaSO3(s) but this solid has no economic value. As a results, they use air injection to convert CaSO3 to CaSO4 which is called Gypsum and has an economic value in making sheet-rocks.
Hope this helps answer your question.
Professor Yehia Khalil
Yale University
USA
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