1156 posts
Burning Question 59
Why does false air infiltration from the bottom stage of a preheater tower increase tower temperature, but in top stage decrease the tower temperature. The preheater system is SLC-S supplied by Fuller. We understand this is a common phenomenon for any other system like ILC, SLC or SLC.
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1156 posts
Re: Burning
I have not observed this phenomenon, however it is perhaps connected with the additional draft that is required to keep the kiln hood under suction when there is inleak in the bottom stage of the preheater. This would cause the thermal energy from the calciner to be drawn up the preheater. Conversely when the inleak is in the cyclones above the calciner then the inleak makes no difference to the draft on the calciner.
1156 posts
Burning Question 60
Why does false air infiltration from the bottom stage of a preheater tower increase tower temperature, but in top stage decrease the tower temperature. The preheater system is SLC-S supplied by Fuller. We understand this is a common phenomenon for any other system like ILC, SLC or SLC.
1156 posts
Re: Burning
We have received some suggestions regarding the possible effects of dam ring height from a major cement plant in North America as follows:
"I would suggest that the particle size distribution (PSD) be looked at for both instances. We have found that by changing internal settings in a VRM there are physical changes in the PSD which will impact the performance of the slag. By changing the PSD as little as 2 microns there is a significant change in the performance while not showing up in a simple test of Blaine." "If the dam ring height is increased the clinker and gypsum will stay on the grinding table longer and possibly be better ground when it exits the table and therefore the circulating load in the mill should be lower.
So the two things to look at are the amount of dehydration of the gypsum with lower dam ring height compared to the higher dam ring height and also the particle size distribution of the finished cement. With a lower dam ring there is the chance that there is more over grinding and a higher concentration of superfines."
Please let us know if you find there is a relationship between dam ring height and particle size distribution or gypsum dehydration as this would make an interesting case study for publication.