Oil refinery plant
Rise in propylene price in the market required increase of propylene production from liquefied gas (LPG). Operation improvement of depropylene column (De-C3) and propylene fractionating С3 column was a key problem to increase the production of the plant.
Design capacity of the gas fractionating unit estimated to be 180,000 tons per year (LPG), its max. capacity is 200000 tons per year. The customer required to increase capacity by 50%, that is 270,000 tons per year to obtain much propylene.
Original standard trays in the depropylene column and depropylene fractionating column were replaced with high performance EDV valve trays that form more vapour passages and contribute to better dispersion of the liquid vapours and have higher mass transfer efficiency than standard trays. New tray connecting constructions were applied to increase the opening and the uniformity of the bubbling. C3 fractional column has 200 trays, their openings reached 15%, area of the discharge pipe equals to 20%. Bubble promoter was installed in the column to develop the characteristics of the tray. Discharge pipe, feed pipe and reflux vapour pipe from reboiler was installed and upgraded.
The capacity of the unit (LPG) after revamping reached 300,000
tons per year, it is 10% more than designed capacity, design value fixed in the contract. The customer cannot increase capacity because of the limited capacity of heat exchangers. Efficiency of the fractionating column increased notably, purity of propane and propylene increased at circulation reflux decrease. Propylene yield increased from 90% to 95%.