Crude oil refined into fuels and chemical compounds by series of distillation and cracking techniques. Refining process proceeds from atmospheric distillation and then to vacuum distillation to separate the crude based on the volatility of the compounds. Modern refineries mostly aim to produce gasoline as primary product. They convert the less volatile compounds to gasoline by cracking technique. One of the famous of is fluidized catalytic cracking. We discuss here about the gasoline generation from vacuum gas oil by fluidized catalytic cracking and develop a process flowsheet. Vacuum gas oil obtained as side stream product of the vacuum distillation unit in most established refineries.
Methods for cracking of vacuum gas oil:
Batch process: By cascade and shifting technique, two to three batch reactors are used to crack the vacuum gas oil. While one reactor in operation and other will stay in regeneration.
Continuous process: This is done by moving bed catalyst between the reactor and regenerator.
About fluidized catalytic cracking:
Cracking operation objective is to breaks the less volatile compounds to more volatile compounds. Using the catalyst to speed up operation is more economical than the thermal application alone. To make the operation more convenient for continuous operation fluidization principles are brought into the design that include both regeneration of catalyst and separation of the products.
Process flowsheet of gasoline generation from vacuum gas oil
Gasoline and LPG obtained from the debutanizer contain sulphur traces in the form of mercaptans. Desulphurization process is necessary to generate consumer grade gasoline and LPG.