21.1 Process Description
To moderate NOx emissions in the flue gas, a Selective Catalytic Reduction (SCR) bed is incorporated in the cold leg of the reformer furnace
...

The purpose of calculation blocks 1-FN-10510 and 1-FN-10506 is to calculate required NH3 flow (initial value or set point value for 1-FIC-10506). The control valve (1-FV-10506) will then trim (fine tune) the NH3 flow to get a set NOx emissions and NH3 slip at the stack.

...get a set NOx emissions and NH3 slip at the stack?
Затем регулирующий клапан (1-FV-10506) отрегулирует расход NH3 так,...

Спасибо.