Abstract:

The reasons of lower yield of propylene in gas fractionation unit were analyzed. Revamping measures were adopted based on the analysis. After revamping, the handling capacity of the fractionator is raised to 90 t/h. The revamping measures include: (i) connecting the high pressure gas discharge line on the top of deethanizer to the feed line of absorption-desorption tower of diesel oil hydrogenation unit, which reduces the discharge of propylene furthest and recovers propylene about 2.88 t/d with an benefit about 7.68 million yuan annually; (ii) using an advanced control system for gas fractionation unit to optimize the operation of propylene rectification tower, which reduces the temperature difference at the bottoms of the propylene tower, improves the purity of propane, and increases the yield of propylene. Through the above three measures, waste of propylene emissions is reduced and the propylene yield of the gas fractionation unit is increased to a great extent.

Key words: gas fractionation unit, propylene, propane, yield, advanced control system