I don't know if you are still having ring issues, but at that section of the kiln I highly doubt it is Sulfur issue. It is simply too hot at 1.3-1-8 diameters up the kiln to have sulfur condensing. This is actually where you would be vaporizing the sulfur in the meal and it would build a ring further up th kiln in the 30-40 m range. You would also have a large amount of buidup in the riser. I would look at the liquid in the feed and more importantly the A/F ratio. You can have similar liquid % with totally different coatibilities based on the A/F ratio. If you are below 1.0, then I would think that is one of the issues. Flame could also be an issue, but I would look at the liquid especially since you are building snowmen in the cooler. That means the clinker is not quenched in the kiln and is still in some form of a liquid phase as it enters the cooler.
Good luck
I don't know have you still any problems with rings. I can answer you I don't thing, that 1,3% of sulfur (in clinker) can brings to ring formation. I absolutely agree with Dirt Burner's opinon and tell you, that you must calculate ASR ratio. This can help you. You also can take chemical analyse of normal coating and save it. When rings are rising you can analyse the ring as well, and compare the two analyses. This statistics will help you for further orientation.
With regards, David.