What causes the DeIsobutanizer tower to heat up, if when Normal butane is added? What's the chemistry behind it? Is it the specific gravity. Isobutane and Normal Butane seem to be so close in gravity.
If the DIB is splitting isobutane and normal butane, adding more normal butane should not have an effect on temperature, only the bottoms (n-butane) flowrate. This is at a constant purity.
If the DIB is splitting isobutane and isobutylene, the higher boiling temperature of normal butane will increase the temperature in the bottom of the column, where the isobutylene is the product.