For most neutralizing amines ...

For most neutralizing amines used in an industrial boiler system, the distribution ratio of amine in the steam versus the liquid is near negligible (there are some exceptions) so that injection into the Deaerator storage section is possible and preferred since the pH boost will enhance the efficiency of the oxygen scavenger.  Care must be taken to separate the feed from catalyzed sulfite since the close proximity pH spike will render the catalyst ineffective.