Plate fin and tube heat exchangers or externally finned tube exchangers have long been employed to recover process heat. These exchangers are most often employed to heat or cool a low density gas stream located on the finned side against a denser fluid with higher heat transfer coefficient within the tubes. The extended surface on the finned exterior pass allows greater heat transfer surface than a bare tube and provides greater heat transfer at a low-pressure drop.
The art has not heretofore recognized the unexpected advantage of using multiple cooling streams on the tube side of one or more heat exchanger and interlacing the heat transfer zones to allow more effective heat transfer and reduce the water dewpoint of the stream to reduce or eliminate visible vapor plume while also reducing SO3 emissions was not recognized in the art.