I am familair with N2 cooldown in a Sulfur Train. One of the benefits is you can cool the unit down more quickly, thereby shortening your down time. But one of the considerations is how much N2 does your plant have available and what other units might be using it if it was a multi unit turnaround. This can be resolved by bringing in N2 trucks, but that costs $$$, so that is always a consideration. I’ve included a link that discusses a case of using CO2 along with N2.