These processes are considered as upgrading processes for vacuum residue.
1. Delayed Coking
This process is based on the thermal cracking of vacuum residue by carbon rejection forming coke and lighter products such as gases, gasoline and gas oils. Three types of coke can be produced: sponge, shot and needle. The vacuum residue is heated in a furnace and flashed into large drums where coke is deposited on the walls of these drums, and the rest of the products are separated by distillation.
2. Flexicoking
In this thermal process, most of the coke is gasified into fuel gas using steam and air. The burning of coke by air will provide the heat required for thermal cracking. The products are gases, gasoline and gas oils with very little coke.
3. Visbreaking
This is a mild thermal cracking process used to break the high viscosity and pour points of vacuum residue to the level which can be used in further downstream processes. In this case, the residue is either broken in the furnace coil (coil visbreaking) or soaked in a reactor for a few minutes (soaker visbreaker). The products are gases, gasoline, gas oil and the unconverted residue.