Shell Consep Trays Improve Diesel Recovery and Naphtha Quality in a DHT Stripper

In 2013, Marathon was unable to make naphtha endpoint specifications due to being at 134% of FRI flood in the rectifying section of the low pressure stripper of a diesel Hydrotreater. Since the tower was flooded and the naphtha had such a high endpoint it could not be sent to the reformer, but it was instead recycled back to the crude unit as slop for cleanup. Shell ConSep trays were installed the rectifying section of the tower during the October 2013 Turnaround. Upon startup, naphtha endpoint met specification, which allowed the naphtha recycle to slop to be eliminated. Further optimization of the reflux up to flooding constraints on the tower allowed the naphtha endpoint specification to be decreased, thus increasing the diesel yield. The Shell ConSep trays allowed optimization of the unit with an increased profit of $6.5MM/yr.