In my opinion,
In any existing facility if any new equipment is to be installed, Change Control shouldbe initiated by the user department [Production-In above mentioned case]. The logic behind this is the Justification i.e. why the new reactor is required … might be increased productivity…
And Definitely once change control is initiated, it must be circulated to all stackholders…for information & necessary actions.
In above mentioned case " Engg- DQ /Installation / Fabrication / Updation of drawings etc. Electrical / Instrumentation / Civil Engg. for respective updates., QC with respect to additional sample loads during OQ / PQ.
In addition to above Don’t forget to add QA also.
Happy Reading !