(20c) Recovery of High Purity Propylene From Refinery LPG

Many refiners are investigating options for manufacturing higher value specialty products from traditional refinery product and intermediate streams as a means of improving weak cash margins that currently  prevail. One potential opportunity is the recovery of high purity propylene from refinery-mixed propane/propylene (PPs) product. Normally, the bulk of this material originates from an FCC Unit and is processed along with butane/butylenes to make gasoline via Alkylation or Polymerization (or Dimerization). However, with the projected declining demand for gasoline in the US many refiners are placing increasing scrutiny on the disposition of this valuable material.

In this paper, a financial analysis is presented for an onsite facility to recover high purity propylene from refinery PPs The critical variables involved in the optimization of equipment sizes and operating costs for the recovery of high purity propylene by conventional distillation and distillation utilizing a heat pump are examined. This is followed by a capital cost estimate for each scheme and ranking based on an investment plus operating cost formula. The scope and capital costs for the associated offsites facilities including prefractionation, treating, storage and shipping are also included. Finally, a financial analysis is presented showing the discounted cash flow rate of return (DCF) as a function of propylene value, utilities cost and facility capacity. The value of the PP feed stream is also calculated as a function of the rate of return for the project and the other variables noted above.