Polymerization

  • In the petroleum industry polymerization is the process by which olefin gases are converted to liquid condensation products that may be suitable for gasoline (hence polymer gasoline) or other liquid fuels.

  • The motor octane number of a polymer gasoline is much lower than the corresponding values obtained from alkylation. This has resulted in the shutdown of the polymerization units in refineries using alkylation.

Other Operations

  • Dewaxing

    • It involves removal of wax from petroleum product.

    • Methyl ethyl ketone (MEK) is used as a dewaxing solvent.

  • Coking: Coking is a thermal process for the continuous conversion of heavy, low-grade oils into lighter products. It involves conversion of the feedstock into volatile products and coke.

    • Delayed coking: It involves severe thermal cracking of heavy residues such as vacuum oil, thermal tars, and sand bitumen. This process produces coke and lighter products such as gases, gasoline and gas oils. The actual coking in this process takes place in the heater effluent surge drum and for this reason the process is called delayed coking.

  • Viscosity breaking (visbreaking) aims to thermally crack long-chain feed molecules to shorter ones, thus reducing the viscosity and the pour point of the product.

  • Propane-deasphalting: Coke-forming tendencies of heavier distillation products are reduced by removal of asphaltenic materials by solvent extraction. Liquid propane is a good solvent (butane and pentane are also commonly used).