SO3 in Hotmeal

Hey Friends;

Our kiln is 3000 tpd, with off line PC and 5 stages PH, our fuel is natural gas, H2S content in the gas is 2%.

SO3 content in our kiln feed is around 0.4% and in our hot meal reach sometimes to  3% which increase the molarity ratio of SO3/ alkali to 1.8. My question is why does SO3 increase in the hotmeal more than others like alkalis? if the reason is the used gas fuel, is there any method to calculate it?

 regards  

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Re: SO3 in Hotmeal

You should check the sulfatisation ratio SO3/alk in your inputs (raw meal+fuels) and compare it to the hot meal sulfatisation. If the latter is higher, it should in principle indicate a strong CaSO4 decomposition cycle in the kiln. Theoretically, the sulfatization of the hot meal could reach any value provided the CaSO4 decomposition cycle is strong enough. The oxygen concentration in the combustion region can strengthen this cycle.

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Re: SO3 in Hotmeal

Hey lalbatros,

Thanks alot for your answer ... Our SO3/alk ratio in the kiln feed in 0.7-0.8 while in the hot meal reach sometimes up to 2.0 and causoing hard coating in rizer duct and ring in burning zone. Could you please tell me what is the reason of CaSO4 decomposition cycle? what do you mean by "oxygen concentration"! do you mean excess O2 in cycone-5?

Regards

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Re: SO3 in Hotmeal

Reducing conditions, i.e. low oxygen, facilitates the decomposition of CaSO4.
Lower sulfatization in raw meal than in hot meal is a suggestion.
You might need to look if the alkalies do not combine with something else, which is chlorine. In the sulfatization ratio, you need -theoretically- to consider only the alkalies that are not combined with chlorine.
In any case, the analysis of alkalies cycles need at least sulfur and chlorine to be considered.

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