What does the answer that you gave me tell us about our argument? What would give you an indication that one of your Mills was failing aside from load and secondary air temperature, The first indication?
I am retired and haven't done coal in years, we used Foster Wheeler, Penn, and CE.
If you don't have tilts not a bad way to do it, if you can get the damned stuff below fusion, the secondary Superheater still takes a beating, but it most give you a good handle on NOX control if the tuning is correct.
It is obvious to me that we are talking about different types of pulverizer and boiler systems. Mine is a B&W Drum type negative pressure natural circulation water wall boiler.
We do not have tilting burners so upper and reheat temps are controlled by loading the top burner mills with less loading, thus less amps.
To tell if one of our pulverizers is malfuncitoning we have people checking them hourly for anything wrong. In the control room I have amp gages, differential air gages Primary air flow and temp gages and secondary air gages along with feeder controls.
To see if something is amiss I look at the amps vs feeder loading (High amps vs low feeder load) for each mill. Then Primary air (low air flow vs feeder load) and mill air temp.
I then check the HEAT RELEASE vs fuel flow. A dropping heat release means am not getting enough fuel into the boiler. It may be a partial feeder pluggage, a slipping feeder belt or low Btu coal. If it is a big rock it will jam the feeder and trip it, then the mill.
An very rapid increase in HEAT RELEASE means I have bogged a mill and it is now blowing out excessive coal into the boiler. Very dangerous, possibility of a boiler explosion exists.
Finally each pulverizer has it’s own characteristics. One may run with a higher amp load than others at the same feeder load. Certain others may bogg or puff while starting up. I know my mills, which ones will bite you in the butt and which might (notice I said “might”)not.
And if any of these run out of coal, the hot PRIMARY air leakage will back up through the feeder and into the silo possibly causing a hopper explosion. We have to send a man to the feeder floor to close the gate between the hopper and the feeder.