The answer will only apply to compressor trip specifically that the rest of the unit is operating normally. it is not uncommon that the suction of the compressor has more than one “dump control valve (s)” to divert suction flow to the flare while maintaining pressure on the column. There are two considerations 1) Control of the pressure of the column so that tower upsets are minimized 2) Issues on the flare load itself that need to be evaluated i.e. WGC is low pressure and back pressure on flare can reduce “relieving” capacity.
Specific to an isolated compressor trip – the controls should be set to dump to flare however with sufficient control as to hold “normal” pressure of the tower. The next step is to reduce overall unit feed rate to minimize flaring and if necessary a controlled shutdown of the unit.
No comment can be made on the impact of catalyst flow or regenerator / reactor pressure balance without knowing unit specific configuration and operating parameters