SlideShare a Scribd company logo

Cracking

Cracking of organics

Cracking

1 of 33
Download to read offline
Cracking
Reactions To Convert Heavy Oils
HYDROCRACKING
H2 + heavy oil → gasoline + diesel
550° F 300° F 450° F
CAT CRACKING
heavy oil → gasoline + propylene, butane,
other “light ends”
550° F 300° F
Reactions To Convert Resid
Resid is the “bottom of the barrel” - the material that
is left in the bottom of the crude/vacuum distillation
towers
COKING
resid + heat → coke + heavy oil
> 900° F solid 550° F
THERMAL CRACKING
Description
a. Because the simple distillation of crude oil produces amounts and types of products
that are not consistent with those required by the marketplace, subsequent refinery
processes change the product mix by altering the molecular structure of the
hydrocarbons. One of the ways of accomplishing this change is through "cracking," a
process that breaks or cracks the heavier, higher boiling-point petroleum fractions into
more valuable products such as gasoline, fuel oil, and gas o ils. The two basic types of
cracking are thermal cracking, using heat and pressure, and catalytic cracking.
b. The first thermal cracking process was developed around 1913. Distillate fuels and
heavy oils were heated under pressure in large drums until they cracked into smaller
molecules with better antiknock characteristics. However, this method produced large
amounts of solid, unwanted coke. This early process has evolved into the following
applications of thermal cracking: visbreaking, steam cracking, and coking.
Visbreaking Process
Visbreaking, a mild form of thermal cracking, significantly lowers the viscosity of heavy
crude-oil residue without affecting the boiling point range. Residual from the atmospheric
distillation tower is heated (800°-950° F) at atmospheric pressure and mildly cracked in a
heater. It is then quenched with cool gas oil to control overcracking, and flashed in a
distillation tower. Visbreaking is used to reduce the pour point of waxy residues and
reduce the viscosity of residues used for blending with lighter fuel oils. Middle distillates
may also be produced, depending on product demand. The thermally cracked residue tar,
which accumulates in the bottom of the fractionation tower, is vacuum flashed in a
stripper and the distillate recycled.
Coking Processes
Coking is a severe method of thermal cracking used to upgrade heavy residuals into
lighter products or distillates. Coking produces straight-run gasoline (coker naphtha) and
various middle-distillate fractions used as catalytic cracking feedstock. The process so
completely reduces hydrogen that the residue is a form of carbon called "coke." The two
most common processes are delayed coking and continuous (contact or fluid) coking.
Three typical types of coke are obtained (sponge coke, honeycomb coke, and needle
coke) depending upon the reaction mechanism, time, temperature, and the crude
feedstock.
Visbreaking
Delayed coking
Ad

Recommended

CATALYTIC REFORMING
CATALYTIC REFORMINGCATALYTIC REFORMING
CATALYTIC REFORMINGtranslateds
 
Hydrotreating process
Hydrotreating processHydrotreating process
Hydrotreating processtranslateds
 
petroleum refining,crackin and synthetic petrol-ppt
petroleum refining,crackin and synthetic petrol-pptpetroleum refining,crackin and synthetic petrol-ppt
petroleum refining,crackin and synthetic petrol-pptKrishna Peshivadiya
 
Treatment of crude oils
Treatment of crude oilsTreatment of crude oils
Treatment of crude oilsKarnav Rana
 
Thermal cracking (2)
Thermal cracking (2)Thermal cracking (2)
Thermal cracking (2)Kumar
 

More Related Content

What's hot

Catalytic reforming process
Catalytic reforming processCatalytic reforming process
Catalytic reforming processIhsan Wassan
 
Visbreaking and Delayed coking
Visbreaking and Delayed cokingVisbreaking and Delayed coking
Visbreaking and Delayed cokingSanyam Jain
 
02 petrochemical processes
02 petrochemical processes02 petrochemical processes
02 petrochemical processesNaveen Choudhary
 
SWEETENING PROCESSES
SWEETENING PROCESSESSWEETENING PROCESSES
SWEETENING PROCESSEStranslateds
 
Reforming of Petroleum
Reforming of PetroleumReforming of Petroleum
Reforming of PetroleumAjmal Arbab
 
Petroleum Refinery Engineering-Part-2-30-July-2016
Petroleum Refinery Engineering-Part-2-30-July-2016Petroleum Refinery Engineering-Part-2-30-July-2016
Petroleum Refinery Engineering-Part-2-30-July-2016Muhammad Rashid Usman
 
Catalyst preparation methods
Catalyst preparation methodsCatalyst preparation methods
Catalyst preparation methods9495094029
 
Oil refinery processes
Oil refinery processesOil refinery processes
Oil refinery processesJithu John
 
Steam reforming - The Basics of Reforming
Steam reforming  - The Basics of ReformingSteam reforming  - The Basics of Reforming
Steam reforming - The Basics of ReformingGerard B. Hawkins
 
Petroleum processing
Petroleum processingPetroleum processing
Petroleum processingmadan lal
 
Liquid fuels presentation
Liquid fuels presentationLiquid fuels presentation
Liquid fuels presentationUsman Arshad
 
Chapter 2 crude_oil_processing2
Chapter 2 crude_oil_processing2Chapter 2 crude_oil_processing2
Chapter 2 crude_oil_processing2Helena Francis
 
Petroleum Refining
Petroleum Refining Petroleum Refining
Petroleum Refining Ajay Sharma
 
Ammonia plant fundamentals
Ammonia plant fundamentalsAmmonia plant fundamentals
Ammonia plant fundamentalsPrem Baboo
 

What's hot (20)

Thermal cracking
Thermal crackingThermal cracking
Thermal cracking
 
Oil Refinery - Processes
Oil Refinery - ProcessesOil Refinery - Processes
Oil Refinery - Processes
 
Petroleum 8
Petroleum 8Petroleum 8
Petroleum 8
 
Catalytic reforming process
Catalytic reforming processCatalytic reforming process
Catalytic reforming process
 
Visbreaking and Delayed coking
Visbreaking and Delayed cokingVisbreaking and Delayed coking
Visbreaking and Delayed coking
 
Crude Oil Refining
Crude Oil RefiningCrude Oil Refining
Crude Oil Refining
 
ADU and VDU.pdf
ADU and VDU.pdfADU and VDU.pdf
ADU and VDU.pdf
 
02 petrochemical processes
02 petrochemical processes02 petrochemical processes
02 petrochemical processes
 
SWEETENING PROCESSES
SWEETENING PROCESSESSWEETENING PROCESSES
SWEETENING PROCESSES
 
Reforming of Petroleum
Reforming of PetroleumReforming of Petroleum
Reforming of Petroleum
 
Chapter 4a heavy_oil2
Chapter 4a heavy_oil2Chapter 4a heavy_oil2
Chapter 4a heavy_oil2
 
Petroleum Refinery Engineering-Part-2-30-July-2016
Petroleum Refinery Engineering-Part-2-30-July-2016Petroleum Refinery Engineering-Part-2-30-July-2016
Petroleum Refinery Engineering-Part-2-30-July-2016
 
Catalyst preparation methods
Catalyst preparation methodsCatalyst preparation methods
Catalyst preparation methods
 
Oil refinery processes
Oil refinery processesOil refinery processes
Oil refinery processes
 
Steam reforming - The Basics of Reforming
Steam reforming  - The Basics of ReformingSteam reforming  - The Basics of Reforming
Steam reforming - The Basics of Reforming
 
Petroleum processing
Petroleum processingPetroleum processing
Petroleum processing
 
Liquid fuels presentation
Liquid fuels presentationLiquid fuels presentation
Liquid fuels presentation
 
Chapter 2 crude_oil_processing2
Chapter 2 crude_oil_processing2Chapter 2 crude_oil_processing2
Chapter 2 crude_oil_processing2
 
Petroleum Refining
Petroleum Refining Petroleum Refining
Petroleum Refining
 
Ammonia plant fundamentals
Ammonia plant fundamentalsAmmonia plant fundamentals
Ammonia plant fundamentals
 

Viewers also liked

Viewers also liked (20)

Gcspwwapril2013linkedin
Gcspwwapril2013linkedinGcspwwapril2013linkedin
Gcspwwapril2013linkedin
 
SRU/TGTU Trains (3)
SRU/TGTU Trains (3)SRU/TGTU Trains (3)
SRU/TGTU Trains (3)
 
Merox Unit
Merox UnitMerox Unit
Merox Unit
 
Maintenance of distillation column asmita
Maintenance of distillation column asmitaMaintenance of distillation column asmita
Maintenance of distillation column asmita
 
Hydrogen production in refinery
Hydrogen production in refineryHydrogen production in refinery
Hydrogen production in refinery
 
Epa
EpaEpa
Epa
 
Polymerization of gasoline
Polymerization of gasolinePolymerization of gasoline
Polymerization of gasoline
 
Process equipment of chemical plant
Process equipment of chemical plantProcess equipment of chemical plant
Process equipment of chemical plant
 
Columbia Project
Columbia ProjectColumbia Project
Columbia Project
 
MerOx
MerOxMerOx
MerOx
 
Methanol Reformer Designs
Methanol Reformer DesignsMethanol Reformer Designs
Methanol Reformer Designs
 
Gasoline engine
Gasoline engineGasoline engine
Gasoline engine
 
Rangkuman penelitian ilmiah
Rangkuman penelitian ilmiahRangkuman penelitian ilmiah
Rangkuman penelitian ilmiah
 
Catalysis in hydtotreating and hydrocracking
Catalysis in hydtotreating and hydrocrackingCatalysis in hydtotreating and hydrocracking
Catalysis in hydtotreating and hydrocracking
 
Distillation Column Design
Distillation Column DesignDistillation Column Design
Distillation Column Design
 
gas absorption
gas absorptiongas absorption
gas absorption
 
Packed tower
Packed towerPacked tower
Packed tower
 
Types and design of the towers trays
Types and design of the towers traysTypes and design of the towers trays
Types and design of the towers trays
 
Gasoline
GasolineGasoline
Gasoline
 
distillation
distillationdistillation
distillation
 

Similar to Cracking

Similar to Cracking (20)

FCC
FCCFCC
FCC
 
Petrochemical tech 7 sem
Petrochemical tech 7 semPetrochemical tech 7 sem
Petrochemical tech 7 sem
 
Elective_Refining 2.pptx
Elective_Refining 2.pptxElective_Refining 2.pptx
Elective_Refining 2.pptx
 
Cracking of petrolium In petroleum geology and chemistry, cracki.pdf
Cracking of petrolium In petroleum geology and chemistry, cracki.pdfCracking of petrolium In petroleum geology and chemistry, cracki.pdf
Cracking of petrolium In petroleum geology and chemistry, cracki.pdf
 
Cracking.pptx
Cracking.pptxCracking.pptx
Cracking.pptx
 
Chapter 4 b4
Chapter 4 b4Chapter 4 b4
Chapter 4 b4
 
FLUID COKING
FLUID COKINGFLUID COKING
FLUID COKING
 
Elective_Refining 1.pptx
Elective_Refining 1.pptxElective_Refining 1.pptx
Elective_Refining 1.pptx
 
catalytic reforming
catalytic reformingcatalytic reforming
catalytic reforming
 
FCC-Ch-21
FCC-Ch-21FCC-Ch-21
FCC-Ch-21
 
thermalcracking.pptx
thermalcracking.pptxthermalcracking.pptx
thermalcracking.pptx
 
Chemistry ppt fuels
Chemistry ppt fuels Chemistry ppt fuels
Chemistry ppt fuels
 
PRESENTATION ON INPLANT TRAINING AT MRPL
PRESENTATION ON INPLANT TRAINING AT MRPLPRESENTATION ON INPLANT TRAINING AT MRPL
PRESENTATION ON INPLANT TRAINING AT MRPL
 
Petro refinery basics
Petro refinery basicsPetro refinery basics
Petro refinery basics
 
Refinery process-description
Refinery process-descriptionRefinery process-description
Refinery process-description
 
Refining Process.pdf
Refining Process.pdfRefining Process.pdf
Refining Process.pdf
 
Conference_Paper
Conference_PaperConference_Paper
Conference_Paper
 
HydroHydro cracking
HydroHydro crackingHydroHydro cracking
HydroHydro cracking
 
5586 5590.output
5586 5590.output5586 5590.output
5586 5590.output
 
KRISHNA(200103040)_IR_PPT.pptx
KRISHNA(200103040)_IR_PPT.pptxKRISHNA(200103040)_IR_PPT.pptx
KRISHNA(200103040)_IR_PPT.pptx
 

More from knowledge1995

More from knowledge1995 (20)

Communicating At Workplace
Communicating At WorkplaceCommunicating At Workplace
Communicating At Workplace
 
Basic Flow Chart
Basic Flow ChartBasic Flow Chart
Basic Flow Chart
 
Glass Manufacturing
Glass Manufacturing Glass Manufacturing
Glass Manufacturing
 
Hardness ppt
Hardness pptHardness ppt
Hardness ppt
 
Fabrication of metals
Fabrication of metalsFabrication of metals
Fabrication of metals
 
Evaporators
EvaporatorsEvaporators
Evaporators
 
Newtons law of viscosity
Newtons law of viscosityNewtons law of viscosity
Newtons law of viscosity
 
Renewable energy
Renewable energyRenewable energy
Renewable energy
 
Fire Triange
Fire TriangeFire Triange
Fire Triange
 
coke and metallurgical coal
coke and metallurgical coalcoke and metallurgical coal
coke and metallurgical coal
 
Animals that are chemical engineers
Animals that are chemical engineersAnimals that are chemical engineers
Animals that are chemical engineers
 
Job interview
Job interviewJob interview
Job interview
 
Letter to editor
Letter to editorLetter to editor
Letter to editor
 
High shear mill
High shear millHigh shear mill
High shear mill
 
Agitaion and mixing
Agitaion and mixingAgitaion and mixing
Agitaion and mixing
 
Sui gas
Sui gasSui gas
Sui gas
 
Principles of effective communication
Principles of effective communicationPrinciples of effective communication
Principles of effective communication
 
sample of critique
sample of critiquesample of critique
sample of critique
 
Types of communication
Types of communicationTypes of communication
Types of communication
 
how to write a paragraph
how to write a paragraphhow to write a paragraph
how to write a paragraph
 

Recently uploaded

SATHVIKA A AD21049 SELF INTRODUCTION.pdf
SATHVIKA A AD21049 SELF INTRODUCTION.pdfSATHVIKA A AD21049 SELF INTRODUCTION.pdf
SATHVIKA A AD21049 SELF INTRODUCTION.pdfSathvikaAlagar
 
Objectives of Software Engineering and phases of SDLC.pptx
Objectives of Software Engineering and phases of SDLC.pptxObjectives of Software Engineering and phases of SDLC.pptx
Objectives of Software Engineering and phases of SDLC.pptxGraceDenial
 
Sample Case Study of industry 4.0 and its Outcome
Sample Case Study of industry 4.0 and its OutcomeSample Case Study of industry 4.0 and its Outcome
Sample Case Study of industry 4.0 and its OutcomeHarshith A S
 
Student Challange as Google Developers at NKOCET
Student Challange as Google Developers at NKOCETStudent Challange as Google Developers at NKOCET
Student Challange as Google Developers at NKOCETGDSCNKOCET
 
20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt
20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt
20CE501PE – INDUSTRIAL WASTE MANAGEMENT.pptMohanumar S
 
Eversendai - HSE Performance Management Systems-R1.pptx
Eversendai - HSE Performance Management Systems-R1.pptxEversendai - HSE Performance Management Systems-R1.pptx
Eversendai - HSE Performance Management Systems-R1.pptxADILRASHID54
 
Into the World of AI GDSC YCCE PPTX.pptx
Into the World of AI GDSC YCCE PPTX.pptxInto the World of AI GDSC YCCE PPTX.pptx
Into the World of AI GDSC YCCE PPTX.pptxGDSCYCCE
 
Deluck Technical Works Company Profile.pdf
Deluck Technical Works Company Profile.pdfDeluck Technical Works Company Profile.pdf
Deluck Technical Works Company Profile.pdfartpoa9
 
Metrology Measurements and All units PPT
Metrology Measurements and  All units PPTMetrology Measurements and  All units PPT
Metrology Measurements and All units PPTdinesh babu
 
SR Globals Profile - Building Vision, Exceeding Expectations.
SR Globals Profile -  Building Vision, Exceeding Expectations.SR Globals Profile -  Building Vision, Exceeding Expectations.
SR Globals Profile - Building Vision, Exceeding Expectations.srglobalsenterprises
 
Biochemical Thermodynamics for Biotechnology
Biochemical Thermodynamics for BiotechnologyBiochemical Thermodynamics for Biotechnology
Biochemical Thermodynamics for Biotechnologyssusere9cd97
 
Introduction about Technology roadmap for Industry 4.0
Introduction about Technology roadmap for Industry 4.0Introduction about Technology roadmap for Industry 4.0
Introduction about Technology roadmap for Industry 4.0RaishKhanji
 
Critical Literature Review Final -MW.pdf
Critical Literature Review Final -MW.pdfCritical Literature Review Final -MW.pdf
Critical Literature Review Final -MW.pdfMollyWinterbottom
 
Bresenham line-drawing-algorithm By S L Sonawane.pdf
Bresenham line-drawing-algorithm By S L Sonawane.pdfBresenham line-drawing-algorithm By S L Sonawane.pdf
Bresenham line-drawing-algorithm By S L Sonawane.pdfSujataSonawane11
 
sahana sri D AD21046 SELF INTRODUCTION.pdf
sahana sri D AD21046 SELF INTRODUCTION.pdfsahana sri D AD21046 SELF INTRODUCTION.pdf
sahana sri D AD21046 SELF INTRODUCTION.pdfsahanaaids46
 
Introduction to Binary Tree and Conersion of General tree to Binary Tree
Introduction to Binary Tree  and Conersion of General tree to Binary TreeIntroduction to Binary Tree  and Conersion of General tree to Binary Tree
Introduction to Binary Tree and Conersion of General tree to Binary TreeSwarupaDeshpande4
 
self introduction sri balaji
self introduction sri balajiself introduction sri balaji
self introduction sri balajiSriBalaji891607
 
STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...
STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...
STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...MianHusnainIqbal2
 
BRINDHA G AD21012 SELF INTRODUCTION.pdf
BRINDHA G  AD21012 SELF INTRODUCTION.pdfBRINDHA G  AD21012 SELF INTRODUCTION.pdf
BRINDHA G AD21012 SELF INTRODUCTION.pdfbrindhaaids12
 

Recently uploaded (20)

SATHVIKA A AD21049 SELF INTRODUCTION.pdf
SATHVIKA A AD21049 SELF INTRODUCTION.pdfSATHVIKA A AD21049 SELF INTRODUCTION.pdf
SATHVIKA A AD21049 SELF INTRODUCTION.pdf
 
Objectives of Software Engineering and phases of SDLC.pptx
Objectives of Software Engineering and phases of SDLC.pptxObjectives of Software Engineering and phases of SDLC.pptx
Objectives of Software Engineering and phases of SDLC.pptx
 
Sample Case Study of industry 4.0 and its Outcome
Sample Case Study of industry 4.0 and its OutcomeSample Case Study of industry 4.0 and its Outcome
Sample Case Study of industry 4.0 and its Outcome
 
Student Challange as Google Developers at NKOCET
Student Challange as Google Developers at NKOCETStudent Challange as Google Developers at NKOCET
Student Challange as Google Developers at NKOCET
 
20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt
20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt
20CE501PE – INDUSTRIAL WASTE MANAGEMENT.ppt
 
Eversendai - HSE Performance Management Systems-R1.pptx
Eversendai - HSE Performance Management Systems-R1.pptxEversendai - HSE Performance Management Systems-R1.pptx
Eversendai - HSE Performance Management Systems-R1.pptx
 
Into the World of AI GDSC YCCE PPTX.pptx
Into the World of AI GDSC YCCE PPTX.pptxInto the World of AI GDSC YCCE PPTX.pptx
Into the World of AI GDSC YCCE PPTX.pptx
 
Deluck Technical Works Company Profile.pdf
Deluck Technical Works Company Profile.pdfDeluck Technical Works Company Profile.pdf
Deluck Technical Works Company Profile.pdf
 
Metrology Measurements and All units PPT
Metrology Measurements and  All units PPTMetrology Measurements and  All units PPT
Metrology Measurements and All units PPT
 
SR Globals Profile - Building Vision, Exceeding Expectations.
SR Globals Profile -  Building Vision, Exceeding Expectations.SR Globals Profile -  Building Vision, Exceeding Expectations.
SR Globals Profile - Building Vision, Exceeding Expectations.
 
Biochemical Thermodynamics for Biotechnology
Biochemical Thermodynamics for BiotechnologyBiochemical Thermodynamics for Biotechnology
Biochemical Thermodynamics for Biotechnology
 
Introduction about Technology roadmap for Industry 4.0
Introduction about Technology roadmap for Industry 4.0Introduction about Technology roadmap for Industry 4.0
Introduction about Technology roadmap for Industry 4.0
 
Critical Literature Review Final -MW.pdf
Critical Literature Review Final -MW.pdfCritical Literature Review Final -MW.pdf
Critical Literature Review Final -MW.pdf
 
Going Staff
Going StaffGoing Staff
Going Staff
 
Bresenham line-drawing-algorithm By S L Sonawane.pdf
Bresenham line-drawing-algorithm By S L Sonawane.pdfBresenham line-drawing-algorithm By S L Sonawane.pdf
Bresenham line-drawing-algorithm By S L Sonawane.pdf
 
sahana sri D AD21046 SELF INTRODUCTION.pdf
sahana sri D AD21046 SELF INTRODUCTION.pdfsahana sri D AD21046 SELF INTRODUCTION.pdf
sahana sri D AD21046 SELF INTRODUCTION.pdf
 
Introduction to Binary Tree and Conersion of General tree to Binary Tree
Introduction to Binary Tree  and Conersion of General tree to Binary TreeIntroduction to Binary Tree  and Conersion of General tree to Binary Tree
Introduction to Binary Tree and Conersion of General tree to Binary Tree
 
self introduction sri balaji
self introduction sri balajiself introduction sri balaji
self introduction sri balaji
 
STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...
STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...
STRETCHABLE STRAIN SENSORS BASED ON POLYPYRROLE AND THERMOPLASTIC POLYURETHAN...
 
BRINDHA G AD21012 SELF INTRODUCTION.pdf
BRINDHA G  AD21012 SELF INTRODUCTION.pdfBRINDHA G  AD21012 SELF INTRODUCTION.pdf
BRINDHA G AD21012 SELF INTRODUCTION.pdf
 

Cracking

  • 2. Reactions To Convert Heavy Oils HYDROCRACKING H2 + heavy oil → gasoline + diesel 550° F 300° F 450° F CAT CRACKING heavy oil → gasoline + propylene, butane, other “light ends” 550° F 300° F
  • 3. Reactions To Convert Resid Resid is the “bottom of the barrel” - the material that is left in the bottom of the crude/vacuum distillation towers COKING resid + heat → coke + heavy oil > 900° F solid 550° F
  • 4. THERMAL CRACKING Description a. Because the simple distillation of crude oil produces amounts and types of products that are not consistent with those required by the marketplace, subsequent refinery processes change the product mix by altering the molecular structure of the hydrocarbons. One of the ways of accomplishing this change is through "cracking," a process that breaks or cracks the heavier, higher boiling-point petroleum fractions into more valuable products such as gasoline, fuel oil, and gas o ils. The two basic types of cracking are thermal cracking, using heat and pressure, and catalytic cracking. b. The first thermal cracking process was developed around 1913. Distillate fuels and heavy oils were heated under pressure in large drums until they cracked into smaller molecules with better antiknock characteristics. However, this method produced large amounts of solid, unwanted coke. This early process has evolved into the following applications of thermal cracking: visbreaking, steam cracking, and coking. Visbreaking Process Visbreaking, a mild form of thermal cracking, significantly lowers the viscosity of heavy crude-oil residue without affecting the boiling point range. Residual from the atmospheric distillation tower is heated (800°-950° F) at atmospheric pressure and mildly cracked in a heater. It is then quenched with cool gas oil to control overcracking, and flashed in a distillation tower. Visbreaking is used to reduce the pour point of waxy residues and reduce the viscosity of residues used for blending with lighter fuel oils. Middle distillates may also be produced, depending on product demand. The thermally cracked residue tar, which accumulates in the bottom of the fractionation tower, is vacuum flashed in a stripper and the distillate recycled. Coking Processes Coking is a severe method of thermal cracking used to upgrade heavy residuals into lighter products or distillates. Coking produces straight-run gasoline (coker naphtha) and various middle-distillate fractions used as catalytic cracking feedstock. The process so completely reduces hydrogen that the residue is a form of carbon called "coke." The two most common processes are delayed coking and continuous (contact or fluid) coking. Three typical types of coke are obtained (sponge coke, honeycomb coke, and needle coke) depending upon the reaction mechanism, time, temperature, and the crude feedstock.
  • 9. CATALYTIC CRACKING Description a. Catalytic cracking breaks complex hydrocarbons into simpler molecules in order to increase the quality and quantity of lighter, more desirable products and decrease the amount of residuals. This process rearranges the molecular structure of hydrocarbon compounds to convert heavy hydrocarbon feedstock into lighter fractions such as kerosene, gasoline, LPG, heating oil, and petrochemical feedstock. b. Catalytic cracking is similar to thermal cracking except that catalysts facilitate the conversion of the heavier molecules into lighter products. Use of a catalyst in the cracking reaction increases the yield of improved-quality products under much less severe operating conditions than in thermal cracking. Typical temperatures are from 850°-950° F at much lower pressures of 10-20 psi. The catalysts used in refinery cracking units are typically solid materials (zeolite, aluminum hydrosilicate, treated bentonite clay, fuller's earth, bauxite, and silica-alumina) that come in the form of powders, beads, pellets or shaped materials called extrudites. c. There are three basic functions in the catalytic cracking process: Reaction: Feedstock reacts with catalyst and cracks into different hydrocarbons; Regeneration: Catalyst is reactivated by burning off coke; and Fractionation: Cracked hydrocarbon stream is separated into various products.
  • 12. FLUID CATALYTIC CRACKING Description a. The most common process is FCC, in which the oil is cracked in the presence of a finely divided catalyst which is maintained in an aerated or fluidized state by the oil vapors. The fluid cracker consists of a catalyst section and a fractionating section that operate together as an integrated processing unit. The catalyst section contains the reactor and regenerator, which, with the standpipe and riser, forms the catalyst circulation unit. The fluid catalyst is continuously circulated between the reactor and the regenerator using air, oil vapors, and steam as the conveying media. b. A typical FCC process involves mixing a preheated hydrocarbon charge with hot, regenerated catalyst as it enters the riser leading to the reactor. The charge is combined with a recycle stream within the riser, vaporized, and raised to reactor temperature (900°- 1,000° F) by the hot catalyst. As the mixture travels up the riser, the charge is cracked at 10-30 psi. In the more modern FCC units, all cracking takes place in the riser. The "reactor" no longer functions as a reactor; it merely serves as a holding vessel for the cyclones. This cracking continues until the oil vapors are separated from the catalyst in the reactor cyclones. The resultant product stream (cracked product) is then charged to a fractionating column where it is separated into fractions, and some of the heavy oil is recycled to the riser. c. Spent catalyst is regenerated to get rid of coke that collects on the catalyst during the process. Spent catalyst flows through the catalyst stripper to the regenerator, where most of the coke deposits burn off at the bottom where preheated air and spent catalyst are mixed. Fresh catalyst is added and worn-out catalyst removed to optimize the cracking process.
  • 13. In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules (e.g. 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 any catalysts. Cracking, also referred to as pyrolysis, is the breakdown of a large alkane into smaller, more useful alkenes and an alkane. Simply put, cracking hydrocarbons is when you separate long chain hydrocarbons into short ones. Fluid catalytic cracking (FCC) is the most important conversion process used in petroleum refineries. It is widely used to convert the high-boiling 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. 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. 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. In effect, refineries use fluid catalytic cracking to correct the imbalance between the market demand for gasoline and the excess of heavy, high boiling range products resulting from the distillation of crude oil.
  • 14. Reactor and Regenerator 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. 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 reactor is in fact merely a vessel in which the cracked product vapors are: (a) separated from the so- called spent catalyst by flowing through a set of two-stage cyclones within the reactor and (b) the spent catalyst flows downward through a steam stripping section to remove any hydrocarbon vapors before the spent catalyst returns to the catalyst regenerator. The flow of spent catalyst to the regenerator is regulated by a slide valve in the spent catalyst line. Since the cracking reactions produce some carbonaceous material (referred to as coke) that deposits on the catalyst and very quickly reduces the catalyst reactivity, the catalyst is regenerated by burning off the deposited coke with air blown into the regenerator. The regenerator operates at a temperature of about 715°C and a pressure of about 2.41 barg. The combustion of the coke is exothermic and it produces a large amount of heat that is partially absorbed by the regenerated catalyst and provides the heat required for the vaporization of the feedstock and the endothermic cracking reactions that take place in the catalyst riser. For that reason, FCC units are often referred to as being heat balanced.
  • 15. The hot catalyst (at about 715 °C) leaving the regenerator flows into a catalyst withdrawal well where any entrained combustion flue gases are allowed to escape and flow back into the upper part to the regenerator. The flow of regenerated catalyst to the feedstock injection point below the catalyst riser is regulated by a slide valve in the regenerated catalyst line. The hot flue gas exits the regenerator after passing through multiple sets of two-stage cylones that remove entrained catalyst from the flue gas. 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. Thus, an FCC unit processing 75,000 barrels/day (12,000,000 litres/day) will circulate about 55,900 metric tons per day of catalyst. Distillation column 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 off-gas. After further processing for removal of sulfur compounds, the cracked naphtha becomes a high-octane component of the refinery's blended gasolines. The main fractionator off-gas is sent to what is called a gas recovery unit where it is separated into butanes and butylenes, propane and propylene, and lower molecular weight gases (hydrogen, methane, ethylene and ethane). Some FCC gas recovery units may also separate out some of the ethane and ethylene. Although the schematic flow diagram above depicts the main fractionator as having only one sidecut stripper and one fuel oil product, many FCC main fractionators have two sidecut strippers and produce a light fuel oil and a heavy fuel oil. Likewise, many FCC main fractionators produce a light cracked naphtha and a heavy cracked naphtha. The terminology light and heavy in this context refers to the product boiling ranges, with light products having a lower boiling range than heavy products.
  • 16. The bottom product oil from the main fractionator contains residual catalyst particles which were not completely removed by the cyclones in the top of the reactor. For that reason, the bottom product oil is referred to as a slurry oil. Part of that slurry oil is recycled back into the main fractionator above the entry point of the hot reaction product vapors so as to cool and partially condense the reaction product vapors as they enter the main fractionator. The remainder of the slurry oil is pumped through a slurry settler. The bottom oil from the slurry settler contains most of the slurry oil catalyst particles and is recycled back into the catalyst riser by combining it with the FCC feedstock oil. The so-called clarified slurry oil is withdrawn from the top of slurry settler for use elsewhere in the refinery or as a heavy fuel oil blending component. Regenerator flue gas Depending on the choice of FCC design, the combustion in the regenerator of the coke on the spent catalyst may or may not be complete combustion to carbon dioxide (CO2). The combustion air flow is controlled so as to provide the desired ratio of carbon monoxide (CO) to carbon dioxide for each specific FCC design. In the design shown in Figure 1, the coke has only been partially combusted to CO2. The combustion flue gas (containing CO and CO2) at 715 °C and at a pressure of 2.41 barg is routed through a secondary catalyst separator containing swirl tubes designed to remove 70 to 90 percent of the particulates in the flue gas leaving the regenerator. This is required to prevent erosion damage to the blades in the turbo-expander that the flue gas is next routed through.
  • 17. The expansion of flue gas through a turbo-expander provides sufficient power to drive the regenerator's combustion air compressor. The electrical motor-generator can consume or produce electrical power. If the expansion of the flue gas does not provide enough power to drive the air compressor, the electric motor/generator provides the needed additional power. If the flue gas expansion provides more power than needed to drive the air compressor, than the electric motor/generator converts the excess power into electric power and exports it to the refinery's electrical system. The expanded flue gas is then routed through a steam-generating boiler (referred to as a CO boiler) where the carbon monoxide in the flue gas is burned as fuel to provide steam for use in the refinery as well as to comply with any applicable environmental regulatory limits on carbon monoxide emissions. The flue gas is finally processed through an electrostatic precipitator (ESP) to remove residual particulate matter to comply with any applicable environmental regulations regarding particulate emissions. The ESP removes particulates in the size range of 2 to 20 microns from the flue gas. The steam turbine in the flue gas processing system is used to drive the regenerator's combustion air compressor during start-ups of the FCC unit until there is sufficient combustion flue gas to take over that task.
  • 25. HYDROCRACKING Description a. Hydrocracking is a two-stage process combining catalytic cracking and hydrogenation, wherein heavier feedstocks are cracked in the presence of hydrogen to produce more desirable products. The process employs high pressure, high temperature, a catalyst, and hydrogen. Hydrocracking is used for feedstocks that are difficult to process by either catalytic cracking or reforming, since these feedstocks are characterized usually by a high polycyclic aromatic content and/or high concentrations of the two principal catalyst poisons, sulfur and nitrogen compounds. b. The hydrocracking process largely depends on the nature of the feedstock and the relative rates of the two competing reactions, hydrogenation and cracking. Heavy aromatic feedstock is converted into lighter products under a wide range of very high pressures (1,000-2,000 psi) and fairly high temperatures (750°-1,500° F), in the presence of hydrogen and special catalysts. When the feedstock has a high paraffinic content, the primary function of hydrogen is to prevent the formation of polycyclic aromatic compounds. Another important role of hydrogen in the hydrocracking process is to reduce tar formation and prevent buildup of coke on the catalyst. Hydrogenation also serves to convert sulfur and nitrogen compounds present in the feedstock to hydrogen sulfide and ammonia. c. Hydrocracking produces relatively large amounts of isobutane for alkylation feedstock. Hydrocracking also performs isomerization for pour-point control and smoke- point control, both of which are important in high-quality jet fuel.
  • 26. Hydrocracking Process a. In the first stage, preheated feedstock is mixed with recycled hydrogen and sent to the first-stage reactor, where catalysts convert sulfur and nitrogen compounds to hydrogen sulfide and ammonia. Limited hydrocracking also occurs. b. After the hydrocarbon leaves the first stage, it is cooled and liquefied and run through a hydrocarbon separator. The hydrogen is recycled to the feedstock. The liquid is charged to a fractionator. Depending on the products desired (gasoline components, jet fuel, and gas oil), the fractionator is run to cut out some portion of the first stage reactor out-turn. Kerosene-range material can be taken as a separate side-draw product or included in the fractionator bottoms with the gas oil. c. The fractionator bottoms are again mixed with a hydrogen stream and charged to the second stage. Since this material has already been subjected to some hydrogenation, cracking, and reforming in the first stage, the operations of the second stage are more severe (higher temperatures and pressures). Like the out-turn of the first stage, the second stage product is separated from the hydrogen and charged to the fractionator.
  • 30. HYDROGEN PRODUCTION Description a. High-purity hydrogen (95%-99%) is required for hydrodesulfurization, hydrogenation, hydrocracking, and petrochemical processes. Hydrogen, produced as a by-product of refinery processes (principally hydrogen recovery from catalytic reformer product gases), often is not enough to meet the total refinery requirements, necessitating the manufacturing of additional hydrogen or obtaining supply from external sources. b. In steam-methane reforming, desulfurized gases are mixed with superheated steam (1,100°-1,600° F) and reformed in tubes containing a nickel base catalyst. The reformed gas, which consists of steam, hydrogen, carbon monoxide, and carbon dioxide, is cooled and passed through converters containing an iron catalyst where the carbon monoxide reacts with steam to form carbon dioxide and more hydrogen. The carbon dioxide is removed by amine washing. Any remaining carbon monoxide in the product stream is converted to methane. c. Steam-naphtha reforming is a continuous process for the production of hydrogen from liquid hydrocarbons and is, in fact, similar to steam-methane reforming. A variety of naphthas in the gasoline boiling range may be employed, including fuel containing up to 35% aromatics. Following pretreatment to remove sulfur compounds, the feedstock is mixed with steam and taken to the reforming furnace (1,250°-1,500° F) where hydrogen is produced.