Fluid Catalytic Cracking Process - WorldOfChemicals

Fluid Catalytic Cracking Process

Fluid catalytic

Fluid catalytic cracking (FCC) is one of the most important cracking process used in refining petroleum. It is majorly used in converting large hydrocarbons of petroleum crude oil, which have high boiling point and high molecular weight into beneficial gasoline, olefinic gases and other such gases.

Fluid Catalytic Cracking Process:

The main reactions involved in Catalytic cracking are:

  • Cracking of paraffins, napthenes, and aromatics side chains.

  • Isomerisation of olefins

  • Dehydrogenation of napthenes and olefins

  • Transfer of hydrogen

  • Cyclization of olefins

  • Condensation of olefins

  • Alkylation and dealkylation

Feedstock for FCC process

Vacuum gas oil (VGO), Hydro-treated VGO, Hydrocracker bottom, Coker gas oil, De-asphalted oil, Reduced crude oil, Vacuum residue (VR).

Steps in the process:

  • Reaction: In this step feedstock reacts with catalyst and cracks down into distinct hydrocarbons.

  • Regeneration: Here, catalyst by burning off coke is reactivated and then recirculated to reactor.

  • Fractionation: Cracked hydrocarbon is separated into different products like LPG, gasoline.

Reactor and Regenerator:

Reactor and regenerator are the main part of Fluid Catalytic Cracking unit.

  • The feedstock is put into unit along with recycle streams and is preheated at temperatures of about 350-420 degree Celsius and then it enters the riser where it comes in contact with regenerated catalyst. Divided catalyst and hydrocarbon vapours then enters reactor and are maintained there at temperature of about 535 degree Celsius.

  • Reactor is a FCC unit division where cracked product vapours are separated from the spent catalyst within the reactor and spent catalyst flows downward removing any hydrocarbons vapours or catalyst coke before returning of the spent catalyst to the catalyst regenerator. Catalyst circulates between reactor and regenerator.

  • The catalyst is regenerated through burning off coke with air blown into the regenerator. The regenerator operates at about 0.7 higher pressure than the reactor. Fresh catalyst is used to optimize the cracking process.

Fractionator/ Distillation Column:

The reaction vapours flows from reactor to the bottom section of distillation column which is commonly referred as fractionator, where this products are distilled into the FCC end products which are cracked petroleum naphtha, fuel oil and off gas. After further processing for sulfur removal, cracked naphtha becomes high octane compound.

Fractionator offgas is sent to a gas recovery unit, where it get separated into butanes and butylene, propane and propylene and into lower molecular weight gases like hydrogen, methane, ethane and ethylene.

Overhead gas in sent to a stabilisation section where, stabilised gasoline and light products are separated, from which LPG is recovered.

Typical operating parameter of FCC:

Raw oil feed: 114 cubic meter/h

Furnace outlet temperature: 291 degree Celsius

Reactor feed temperature: 371 degree Celsius

Reactor vapour temperature: 549 degree Celsius

Major suppliers of FCC catalyst

The major suppliers of FCC catalysts worldwide are:

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