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.

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.

I have two questions: What is the effect of NO_x and SO_x in controlling the burning zone temp and what other parameters like kiln torque, kiln inlet oxygen or if anything else affects the kiln operation. Secondly: How to improve the ventilation in ball mills, as we observe the coating formation on the balls is on the high side.

NO_x and kiln torque are both good indicators of the temperature in the burning zone of the kiln. This is key to ensuring stable operation and good combination of the clinker. Kiln inlet oxygen is a good indicator of the combustion conditions in the kiln where a small excess of oxygen is necessary to ensure burning in oxidising conditions. SO_x rises if there is reductive burning and CO present in the burning zone therefore this reinforces the kiln inlet oxygen measurement. To improve the ventilation in the ball mill you need to increase the speed of the induced draft fan. However if you are suffering coating of the media this is more likely related to temperature control in the mill. This is a function of the clinker temperature, ventilation and the cooling with water injection.