You will either need ridiculously high furnace outlet temperatures to achieve a 95% 180 recovery, or stripping steam/gas. Look at the flowsheet of a Crude Distillation Unit. That is what you are doing - just you don't need to lift kerosene or diesel. You also probably will need to have a vapour overhead product and a water overhead draw, because the feed coming form desalting will be wet (and if you use stripping steam the water needs to come out in the overhead drum). Increase your furnace outlet temperature (you haven't disclosed that, but your vapour fraction out of the furnace needs to be significantly higher than the fraction of naphtha in the feed.