Direct steam injection for SWS is typically historic. It was a cheap way to build strippers.
A reboiler is current state of the art.
Advantage of a reboiler:
Less process water (10-20%)
recovery of valuable condensate which is otherwise downgraded to effluent water.
I would agree that this should be considered as fouling service although it is not that obvious.
It is possible that operation on a too low pH or other non-optimal process conditions of the TGTU cause corrosion of the quench tower and subsequent fouling of the heat exchangers.
How stable is the operation of the TGTU?
There is a limit for the sodium content. It is basically the maximum solubility of Sodium in amine solutions.
It is somewhere between 1 and 2 %.
The possibilities of Sodium entrainment from an amine unit are rather small. The amine itself (containing the sodium) can be entrained.
Egbert van Hoorn