I helped with a project about 10 years ago where Petrolite and Shell did a lot of work to characterize the various filming and neutralizing amines and to model their behavior in the overhead system. The standard flow sheeting models usually only have the ability to model ammonia chloride and all of the neutralizers/filmers form salts that can behave differently. They key is determining when a salt will begin to form and deposit out and where is this point in relation to the dew point. Unfortunatly, each system is different and must be modeled.