(6g) Energy Saving by Integration of Refining and Petrochemical Plant

The catalytic naphtha reforming unit produced high octane product for gasoline and aromatics for petrochemical products in Tokuyama refinery of Idemitsu Kosan, Japan. An half amount of the high octane product were fed to four distillation trains to produce mixed xylene and gasoline pool. The mixed xyene and remaining high octane product were the feedstock of a para-xylene unit in petrochemical facility which located neighbored the refinery.

We investigated the possibility of saving energy by integration of the four distillation trains and the para-xylene unit by using a process simulator. We examined how to maintain para-xylene and gasoline pool production and our solution was that only changing the operating conditions of the first and second distillation column, and the third and forth distillation columns do not need to operate to produce mixed-xylene in the refinery. The new operating conditions were that C6- fraction was distilled in the first column and raw toluene was separated as distillate in the second column. The bottom of the second column, the mixture of mixed-xylene and C9 aromatics heavier would be the feedstock of the para-xylene unit. As the feed-rate of C9 aromatics column in the para-xylene unit became approximately twice of the original design, the trayed column should replaced with a new forth generation random packing, Raschig Super-Ring.

We carried out successfully energy conservation job that needed some modifications of the piping, storage tanks, installation of a new heat- exchanger for raw toluene and replacement of the internal of C9 aromatics column during turnaround in 2004. The two distillation columns in the refinery and the para-xylene unit are running well after the turnaround. Energy saving which equivalent to 6,000 KL of fuel oil was achieved by the integration of refining and petrochemical plant