adsoption absorption cracking
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8/4/2019 Adsoption Absorption Cracking
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GET INDUCTION PROGRAMME
ADSORPTION
ABSORPTIONCRACKING
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ADSORPTION
Preferential partitioning of substances from the
gaseous or liquid phase onto the surface of a
solid substrate is Called Adsorption
Distillation : Relative volatility
Absorption: Solubility
Extraction: Distribution Coefficient
Adsorption: Pore diameter
Examples of Uses of Adsorption:
a. Removal of CO, CO2, CH4 from Hydrogen in PSA Unit
b. Use of desiccant to prevent corrosion in sparestrans ortation
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Adsorbents – Desirable
Properties
Should have large internal surface areaAdsorbent should be regenerableShould not age easily
Mechanical Strength
Pore size
Adsorption - Surface Phenomenon -van der Waals forces and
electrostatic forces between adsorbate molecules and the
atoms which compose the adsorbent surface. Thus
adsorbents are characterized first by surface properties suchas surface area and polarity.
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Absorption
The process of removal of one or more selectedcomponents from a mixture of gases into suitable liquid
by interphase mass transfer controlled largely by
rate of diffusion.
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Absorption - type
Absorption - Physical
Absorption - Accompanied by Chemical Reaction
Example : Absorption of H2S in water
Absorption of H2S in MDEA
Depends upon solubility of solutes to be removed in liquidNo chemical reaction
Little heat released
Depends on chemical reaction of solute with liquid
Significant heat release
(CH2OHCH2)2NCH3 +H2S (CH2OHCH2)2NSCH3
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Equipment
Plate Tower
Packed Tower
Type of Trays
DowncomerDistributor pipe
Packing support plate
Packing
Redistribution of liquid
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Cracking
Cracking is the process of decomposition of high
molecular weight hydrocarbons to more valuable
lower molecular weight hydrocarbon.
Types : a. Thermal
b. CatalyticFixed bed
FCCMoving Bed
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Thermal Cracking
Thermal Cracking is defined as the thermal decomposition,
under pressure, of large hydrocarbon molecules to form
smaller molecules
C10H22 C8H17 ° + C2H5°
C2H5° + C6H14 C2H6 + C6H13°
C6H13° C5H10 + CH3°C8H17° C4H8 + C4H9°
CH3° + H° CH4
C4H9° C4H8 + H°
Large Molecules decompose into smaller :
Free radicals react with other molecules to form sat HC & FR.
Termination of chain reaction :
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Thermal Cracking
Vacuum
Flasher
Surge Drum
PC
TC
Fuel
FC FC
Thermal
Residue
Visbreaking Residue
Steam
PC
Sour Water
Thermal Cracked Naphtha
LongResidue
TC
PC
TC
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Thermal Cracking -Salient
Features
Design of all equipment is to minimize coke formation
Heaters : tube diameter, Charge stock velocities, Heating rate
Temperature, Metallurgy, Coke prevention,Zone temperature control.
Soak Drum Gas oil stream is frequently used to wet the walls
of soak drum to prevent coke accumulation.
Use of stand by drum.
Pumps Should be able to handle high temp, corrosive liq.
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Fixed Bed Catalytic Cracking
Charge
Heater
Turbo Compressor
Air Heater
Heat Exchanger
Heavy CatalytGas Oil
Light
CGO
Motor
Gasoline
to
Stabilizer
Wet Gas to
Stabilizer
Fresh Air
Spent Air
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Moving Bed Catalytic Cracking
Reactor
Kiln
Flue Gas
Steam
Lift Engaging Hopper
Elutriator
Lift Disengaging Hopper
F r e s h C a t a l y s t
S t o r a g e
Steam
BFW
Purge Steam
Reactor Product
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Fluidized bed Catalytic Cracking
Objective : To convert heavy fuel components into high-octane
motor gasoline blending components.
By products: Coke, C4 feed.
Interface with other Units: Overhead gas
Gasoline
BottomsProcess Description
Health, Safety, Environment & Fire (HSEF)
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FCC - Process Flow
Flue Gas to PRTReactor
Stripper Debutanizer
LPG to
Merox
105-180 Naph toHNUU / Heavy
Mogas header
155-180 Naph
to Reactor
Naphtha
Splitter
C5-105 Naph. to
LNUU / Merox
C6-105 Naph. to
LNUU / Light
Mogas header
Depentanizer
C5 to SHP /
LNUU
C6-105 Naph.to LNUU
Deisohexanizer
i-C6
to Light
Mogas header
C7-105 Naph.
to Riser
Compressor
HP
Receiver
MC ovhd liquid
Primary
Absorber
Rich
Oil
Sponge
Absorber
Rich
Amine
to ATU
Lean
Amine
fr ATU
Treated Gas
to FG System
HP Liquid to Stripper
Lean
Oil
Amine
Absorber
Receiver
FLUIDIZED CATALYTIC CRACKING UNIT
3rd
stg
sep.
Orifice
Chamber
ExpanderSteam
Turbine
Motor/
Generator
Flue Gas Cooler
BFWHP
Steam
Stack
Process Air to Rg
Air
Raw oil
Rx
Vapors
1
10
26
Heavy cracked Naphtha
Product (180-215 °C)/
Heavy Mogas header
Heavy Naphtha (155-215°C)to Reactor
42
MP
Steam
1
6
6
1
Light Cycle Oil Product to
Diesel Blending System
MP
Steam
Main
Column
Light
Cycle
Oil
Stripper
Heavy
Naphtha
Stripper
Reflux
Drum
Fuel Oil Product to
FO System
MC ovhd vapor
M ai n A i r
Blower
Fuel
Gas Process
Air
Combu-
stor
Regenerator
Stripper
Riser
Regenerated
Catalyst
Spent
Catalyst
To Recovered Cat. Hopper
4th
stg.
sep.
546 oC
714 oC
121 oC1.55 Kg/cm2g
2.34 Kg/cm2g
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Hydrocracker
Objective : To convert fuel oil components into Naphtha,
Kerosene, and gas oil
Interface with other Units: Feed Stock
Hydrogen comes from HMU
LPG
Naphtha
KeroseneProcess Description
HSEF
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Hydrocracker - Process Flow
TC
Fist Stage
ReactorrSecond
Stage
Reactorr
High
PressorSeparator
Fractionation
PC
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