Catalytic
Cracking
unit Made by
Group 11:
عبدالله حمدى عبدالمحسن ضباب
محمد اشرف خميس الشايب
محمد مجدى محمد البحيرى
يوسف محمود محمود عوض
Firs What is
t, cracking?
In cracking, hydrocarbons are subjected to
relatively high temperatures over a period of
time
The larger molecules are then broken down
into smaller ones, which has more valuable.
Catalytic
Cracking
Catalytic cracking is a conversion process that can be applied to a
variety of feedstocks ranging from gas oil to heavy crude oil
1. with a catalyst,
2. under suitable conditions of temperature, pressure, and residence
time
The feedstock is then converted into gasoline and lower boiling point
products
The process is carried out in a catalytic cracking unit, which is also known as a fluid
catalytic cracking (FCC) unit
Catalytic
Cracking
Heavy Crude Lower BP
Products
Catalys
t
It has the following properties:
1- Change the speed of a chemical reaction
2- Chemically, not changed.
3- Inhibit certain chemical reactions (undesirable)
4- Selectively promote certain types of reactions
Catalys
t
Catalysts are used either in the form of pellets or as a fine powder.
There are two types of catalysts:
1. Natural clays
2. Synthetic like zeolite and silica-alumina catalysts. They are the most common
types of catalysts used in catalytic cracking units
The choice of catalyst used in a catalytic cracking unit depends on several factors,
including the type of feedstock being processed, the desired product yield and
quality, and the operating conditions of the unit.
Catalys
t
It is therefore necessary to regenerate the catalyst in the regenerator so that it
may be used repeatedly, by burning off the coke so that the activity is restored.
Why to choose catalytic over thermal
cracking?
1. Less formation of light gases and increased yield of more useful gases
• Formation of iso-paraffin and aromatic hydrocarbons
2. More hydrocarbons produced
3. Enhanced value of the products with less impurities (sulfur)
• Production of gasoline of higher anti knock value
• Improves the stability of the gasoline and reduces the tendency towards gum
formation
• Octane number of gasoline from catalytic cracking ranges between 78-82,
while for thermal cracking it ranges between 60-70
Why to choose catalytic over thermal
cracking?
4. More energy-efficient and environmentally friendly
5. Flexibility, can be designed to process a wide range of feedstocks
6. catalyst regeneration in catalytic cracking units allows for continuous use of
the catalyst and reduced cost
Why to choose catalytic over thermal
cracking?
Still, although it has many benefits, thermal cracking, may be more suitable for
certain feedstocks or product requirements.
Depending on:
1. the properties of the feedstock,
2. the desired products and yields
3. the operating conditions of the refinery
Catalytic Cracking
Feedstock
Feedstocks that are more suitable for catalytic cracking are:
1. a distillate, To reduce the amount of coke deposited on the catalyst
2. Lower in boiling point
3. Low in carbon residue and metals content,
4. Higher in API gravity,
5. Higher in sulfur and nitrogen content
6. Lower in viscosity
However, like said before, the specific properties of the feedstock and the desired
products and yields must be carefully evaluated to determine the most efficient
and effective refining process.
Catalytic Cracking Process
The unit has a:
1. Reactor, where the actual cracking process takes place.
2. catalyst circulation system.
3. Regenerator, where the catalyst is regenerated after use.
Catalytic Cracking Process
The process in general is:
1. The feedstock is mixed with a catalyst
2. The mixture is then heated to high temperatures in the reactor.
3. The catalyst breaks down the large hydrocarbon molecules in the feedstock into
smaller molecules, which are then separated and collected
4. The separated products are then sent for further processing and refining to produce
various types of fuels
5. The deactivated catalyst during the cracking process, is sent to the regenerator where
it is burned with air to remove the carbon deposits and restore its activity.
Catalytic Cracking Process
Classification of catalytic cracking processes based on catalyst:
1. Fixed bed, (Houdry)
2. Moving bed, (TCC)
3. Fluid processes. (FCC)
Catalytic Cracking Process Oil vapor&oil
absorbed on
catalyst
The Houdry Fixed Bed Process
0'5 to 3 kg/cm2
below 480 C below 565 C
Heat supplied during reaction and removed after compusion
Catalytic Cracking Process
The Houdry Fixed Bed Process
Disadvantages:
1. Frequent changes in the operating conditions
2. Equipment is exposed to severe stresses
3. Expensive automatic cycle-timing equipment is required.
4. choice of feedstock is limited by volatility considerations
5. Heavy feedstocks cannot be processed
Catalytic Cracking Process
The Thermofor Catalytic Cracking Moving Bed Process (TCC)
T < 590C
400-510C To avoid catalyst
deterioration
1-2kg/cm2
Catalytic Cracking Process
The Thermofor Catalytic Cracking Moving Bed Process (TCC)
Advantages:
1. Was made to overcome the disadvantages of the fixed bed process.
2. Catalyst, is continuously transported from the reactor to the
regenerator
Disadvantages:
3. Ratio of catalyst circulation rate to oil feed rate is low.
Catalytic Cracking Process
The Fluid Catalytic Cracking Process (FCC)
Catalytic Cracking Process
The Fluid Catalytic Cracking Process (FCC)
Advantages:
1. the fluidized bed reactor allows for better mixing and heat transfer,
enhancing the cracking reaction.
2. the fine powder catalyst used in FCC has a larger surface area,
which increases its activity and selectivity
Disadvantages:
3. high temperatures and pressures cause catalyst deactivation and
erosion to reactor and other equipment
4. produces some coke, which lead to catalyst deactivation and fouling
of the equipment
5. Requires a more energy to maintain the high temperatures and
fluidization of the reactor
Catalytic Cracking Process
Two Stage Catalytic Cracking
Advantages:
1. Reduced gases and heavy products
2. More gasoline
Disadvantage:
3. Higher capital cost
Thanks
!
Made by
Group 11:
عبدالله حمدى عبدالمحسن ضباب
محمد اشرف خميس الشايب
محمد مجدى محمد البحيرى
يوسف محمود محمود عوض
