(229d) Maximize Propylene Recovery from a Fcc Gas Plant

In the middle of 2002 the FCC Unit at PreemRaff was revamped to boost the capacity and increase the light ends recovery. Several distillatiin columns were retrofitted with advanced Mass Transfer Components, while a new Propylene/Propane Splitter was added at the downstream Gas Concentration Unit. The goal was to maximize the Propylene recovery with a polymer grade quality, which typically requires a huge number of fractionation trays. Due to plant lay-out constraints, there was room for one single column only. To maximize the energy saving a heat pump system was chosen. Due to local Refinery regulations, the column internals had to be designed for an easy accessibility and fast inspection of the vessel; therefore the multiple downcomer trays, typically selected for this duty, could not be used. Following a deep technical study, including process, hydraulic, and mechanical factors, the VGPlus high performance trasy were installed.

The scope of the paper is to describe the approach to such challenging project and report the plant data to highlight the achieved results.