MEWAR UNIVERSITY

DEPARTMENT OF CHEMICAL ENGINEERING

Topic: CATALYTIC CRACKING (FLUID CATALYTIC

CRACKING) OF PETROLEUM PRODUCTS

PETROCHEMICAL TECHNOLOGY

Presented To:

Mr. M. Alam

Head Of Dept.

Chemical Engg. Dept.

Presented By:

Kumar Rakesh

B.Tech Final Year

11MUBCHE09

Chemical Engg. Dept.

CONTENTS

Introduction to cracking

Types of Cracking

Introduction to Fluid Catalytic Cracking

Process Description

Flow Diagram of FCC

CRACKING AND ITS TYPES

Cracking is the process whereby complex organic molecules such

as kerogens or heavy hydrocarbons are broken down into simpler

molecules such as light hydrocarbons, by the breaking of carbon-

carbon bonds in the precursors.

The rate of cracking and the end products are strongly dependent on

the temperature and presence of catalysts.

Cracking is the breakdown of a large alkane into smaller, more

useful alkanes and alkenes.

Cracking methodologies

Thermal Methods

Catalytic Methods

INTRODUCTION

Fluid Catalytic Cracking is widely used to convert the high-boiling,

high-molecular weight hydrocarbon fractions of petroleum crude

oils to more valuable gasoline, olefinic gases, and other products.

Cracking of petroleum hydrocarbons was originally done by thermal

cracking, which has been almost completely replaced by catalytic

cracking because it produces more gasoline with a higher octane

rating.

It also produces byproduct gases that are more olefinic, and hence

more valuable, than those produced by thermal cracking.

INTRODUCTION TO FLUID CATALYTIC

CRACKING PROCESS

The feedstock to an FCC is usually that portion of the crude oil that has an

initial boiling point of 340 °C or higher at atmospheric pressure and an

average molecular weight ranging from about 200 to 600 or higher. This portion

of crude oil is often referred to as heavy gas oil or vacuum gas oil (HVGO).

The FCC process vaporizes and breaks the long-chain molecules of the high-

boiling hydrocarbon liquids into much shorter molecules by contacting the

feedstock, at high temperature and moderate pressure, with a fluidized

powdered catalyst.

• The preheated high-boiling petroleum feedstock (at about 315

to 430 °C) consisting of long-chain hydrocarbon molecules is

combined with recycle slurry oil from the bottom of the

distillation column and injected into the catalyst riser where it

is vaporized and cracked into smaller molecules of vapor by

contact and mixing with the very hot powdered catalyst from

the regenerator.

• All of the cracking reactions take place in the catalyst riser

within a period of 2–4 seconds.

• The hydrocarbon vapors "fluidize" the powdered catalyst and

the mixture of hydrocarbon vapors and catalyst flows upward

to enter the reactor at a temperature of about 535 °C and a

pressure of about 1.72 barg.

• The catalyst is regenerated by burning off the deposited coke

with air blown into the regenerator.

• The amount of catalyst circulating between the regenerator

and the reactor amounts to about 5 kg per kg of feedstock,

which is equivalent to about 4.66 kg per litre of

feedstock.[1][7] Thus, an FCC unit processing 75,000 barrels

per day (11,900 m3/d) will circulate about 55,900 tonnes per

day of catalyst.

• The reaction product vapors (at 535 °C and a pressure

of 1.72 barg) flow from the top of the reactor to the bottom

section of the distillation column (commonly referred to as

the main fractionator) where they are distilled into the FCC

end products of cracked naphtha, fuel oil, and offgas.