Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly...

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Refinery Structure- Evolution Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial fuels Hydro treating units added for fuels quality improvement Addition of several conversion processe to improve: fuels recovery efficiency, further quality improvement, process heavier fractions / crudes & energy efficiency

Transcript of Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly...

Page 1: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

Refinery Structure- EvolutionRefinery Structure- Evolution

Topping Refinery

Hydroskimming Refinery

Conversion Refinery

Mainly fractionation by distillationFor production of industrial fuels

Hydro treating units added for fuelsquality improvement

Addition of several conversion processesto improve: fuels recovery efficiency, further quality improvement, process heavier fractions / crudes & energy efficiency

Page 2: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

Processing of light crude Processing of light crude

Processing of light crude, even in a complex/modern refinery with FCC,

hydrocracking etc. does not yield a satisfactory product distribution.

The amounts of fuel oil are too high.

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Processing of heavy oilProcessing of heavy oilFor heavy oil the situation is even worse with ~ 50% fuel oil being produced even in a complex /modern refinery.

Fuel oil is worth < original crude. The value of the products decreases in the order: gasoline> kerosene/gas oil > crude oil > fuel oil.

Bottom of the barrel treatment is vitalChallenge – Meeting Strict Quality standards & Increasing Demand

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Page 5: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.
Page 6: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

Gasoline Specs-IndiaGasoline Specs-India

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Diesel Specs- IndiaDiesel Specs- India

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Structure of refineryStructure of refinery

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Flow Scheme of modern oil refineryFlow Scheme of modern oil refinery

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Catalytic processes in refineryCatalytic processes in refinery

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Petroleum refining processesPetroleum refining processes

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Petroleum Refining- Types of OperationsPetroleum Refining- Types of OperationsFractionation (distillation)-

Separation of crude oil in atmospheric and vacuum distillation towers into groups of hydrocarbon compounds of differing boiling-point ranges called "fractions" or "cuts."

Conversion Processes Changing the size and/or structure of hydrocarbon molecules via different processes:

Decomposition (dividing) by thermal and catalytic cracking; Unification (combining) through alkylation and polymerization; andAlteration (rearranging) with isomerization and catalytic reforming.

Treatment Processes For additional processing and to prepare finished products. Removal or separation of aromatics / naphthenes/ impurities / undesirable contaminants. Chemical or physical separation e.g. dissolving, absorption, or precipitation Desalting, drying, hydro de-sulfurization, sweetening, solvent refining, solvent extraction, and solvent de-waxing.

Page 13: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

Processes in Oil RefiningProcesses in Oil Refining

Physical Thermal CatalyticDistillation Visbreaking Fluid Catalytic

Cracking

Solvent extraction

Delayed coking

Hydrotreating

Solvent dewaxing Fluid cocking Catalytic Reforming

Propane deasphalting

Flexi coking Catalytic dewaxing

Blending Hydrocracking

Isomerization

Alkylation

Etherification

Polymerization

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Petroleum - PropertiesPetroleum - PropertiesDensity Specific gravity - Ratio of mass of specific volume to mass of the same

volume of water, both at the same temperatureAPI GravityDegrees API = (141.5/Specific gravity at 60/60 °F) – 131.5

Viscosity- cP- Flow characteristicsKinematic viscosity/fluidity = Viscosity/ Specific gravity

Carbon residue (wt%) Carbonaceous residue left out after destructive distillation- non-volatile part of petroleum/petroleum products Ramsbottom method- ASTM D 189 IP3Conradson method - ASTM D 189 IP4Viscosity and Asphaltenes, Nitrogen & Sulfur contents increase with

increasing carbon residueIndicates the potential for coke formation

Signify Light/Heavy character of Crude oilSignify Light/Heavy character of Crude oil

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Petroleum - PropertiesPetroleum - Properties

Aniline point

Temperature at which exactly equal parts of two components are

Miscible- Aniline & Any petroleum fraction/oil

Increases slightly with molecular weight

Increases rapidly with paraffinic character/

Higher the aniline point- lower is the aromatics content in the fraction

Reid vapor pressure (RVP)

A measure of the volatility of gasoline. It is defined as the absolute vapor pressure exerted by a liquid at 100 °F (37.8 °C) as determined by the test method ASTM-D-323.

RVP differs slightly from the True Vapor pressure (TVP) of a liquid due to some small sample vaporization and the presence of water vapor and air in the confined space of the test equipment, i.e. the RVP is the absolute vapor pressure and the TVP is the partial vapor pressure

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Petroleum - PropertiesPetroleum - PropertiesCloud point

The temperature of the test specimen at which wax crystals have formed sufficiently to be observed as a cloud from a petroleum fractionApplicable for petroleum products and biodiesel fuelsAn index of the lowest temperature of their utility for certain applications. Petroleum blending operations require a precise measurement of the cloud point.

Smoke point Provides an indication of the relative smoke producing properties of kerosines and aviation turbine fuels in a diffusion flame. Related to the hydrocarbon type composition of such fuels, esp. aromaticsMore aromatic the fuel the smokier the flame. A high smoke point indicates a fuel of low smoke producing tendency.The smoke point is quantitatively related to the potential radiant heat transfer from the combustion products of the fuel.

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Petroleum- PropertiesPetroleum- Properties

Pour pointThe lowest temperature at which it will pour or flow under prescribed conditions. It is a rough indication of the lowest temperature at which oil is readily pumpable. Can be defined as the minimum temperature of a liquid, particularly a lubricant, after which, on decreasing the temperature, the liquid ceases to flow.

UOP K factor ( Watson Characterization factor)

K = 3√ TB/ S TB- Average molal BP in Deg.Rankine ; S- Sp.gravity at 60°F

Page 18: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

Crude Assay- Properties that determine the processibility, product pattern & hence the cost of the crude

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These fractions need go through regular

refining processes to yield fuels of acceptable grade

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Thermal Processes:Thermal Processes:

Cracking & CokingCracking & Coking

Page 21: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

DesaltingDesaltingObjectivesRemoval of water, inorganic salts, water soluble metals & suspended

solids from crude oil –Prevention of corrosion, fouling & plugging of equipments

ProcessTwo stage desalting is carried out, with removal of most of the water at first

stage, followed by addition of dilution water in the second stage to extract

soluble salts & metals. Process conditions are 90-150°C and 50-250 psi.

Surfactants are added to demulsify & achieve proper separation and remove

water by settling. Application of electrostatic coalescing is also adopted

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Thermal crackingThermal crackingDubbs process

Thermal cracking of reduced crude at 455-540°C & 100-1000 psi

Major products- Gasoline & middle distillates Soaking of light & heavier fractions & further cracking

Thermal cracking of Reduced crude oilFeedstock; API gravity 25 °C ; IBP- 227°C

Cracking parameters- 500 °C ; Soaker pressure; 225 psi Product yields (Vol%)

Gasoline Heating oil

Gas - 1.0

Naphtha 57.5 42.0

Heating oil 0.0 23.0

Residuum 37.5 34.0

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VisbreakingVisbreaking

Viscosity-breaking- Cracking to reduce the viscosity A mild form of thermal cracking of the residue (10% conversion), at 50-300 psig

pressure at 455-520°C to reduce viscosity/ pour point. Liquid phase cracking. Process optimized to minimize coke formation Water injected with the feed to provide turbulance & control temperature Residue from Atmos. / Vac. distillation units can be used Coil/Furnace type- high temp. & short residence time Soaker type- Lower temp. & longer residence time Product stability is the issue- Olefinics

Feedstock From ProcessTypical products To

Residual Atmospheric tower & Vacuum tower

Decompose Gasoline or distillate

Hydrotreating

      Vapor Hydrotreater

      Residue Stripper or recycle

      Gases Gas plant

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Visbreaking- Yield patternVisbreaking- Yield pattern

Luisiana Vacuum Residue

Arabian Light Atmos.residue

Feed stock

Gravity API

Carbon residue

Sulfur wt %

11.9

10.6

0.6

16.9

3.0

Product yields

Naphtha 6.2 7.8

Light gas oil 6.3

Heavy gas oil 70.8

Residuum

Gravity API

Carbon residue

Sulfur wt %

88.4

11.4

15.0

0.6

20.9

1.3

5.0

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Delayed cokingDelayed cokingThe feed is subjected to thermal cracking, in a coke drum, under high pressure & temperature-15-90 psig & 415-450 °C Held (delayed) ~24 hours for the process to get completedTwo coke drums used, one for processing and the other for coke

removal & cleaningVirtually eliminates residue fraction-forms solid carbon/fuelHighly aromatic coke, retains S,N & metalsNaphtha, LGO & HGO – used for gasoline/diesel/FCCU after hydrotreating

Luisiana Resid

Kuwait Resid

Feed stock

Gravity API

Carbon residue

Sulfur wt %

12.3

13.0

0.7

6.7

19.8

5.2

Product yields

Naphtha 22.8 26.7

Light gas oil 18.4 28.0

Heavy gas oil 37.6 18.4

Coke

Sulfur wt %

23.7

1.3

30.2

7.5

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Both FLUID COKING (1954) and FLEXICOKING (1976) use fluid bed technology Thermally convert heavy oils such as vacuum residue, atmospheric residue,

tar sands bitumen, heavy crudes, deasphalter bottoms & other heaviers Heat for the process is supplied by partial combustion of coke. Remaining coke is

withdrawn as product Feed is injected into a fluidised bed with hot coke particles. Steam is injected at the

bottom for fluidization New coke formed is deposited as a thin layer on the surface of circulating coke

particles; Coking vessel temp-480-565°C;residence time 15-30 sec.

• FLEXICOKING goes one step beyond FLUID COKING: in addition to generating clean liquids, FLEXICOKING also produces a low-BTU gas in one integrated processing step that can virtually eliminate petroleum coke production.

Fluid Coking & Flexi CokingFluid Coking & Flexi Coking

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Page 29: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

Thermal Processes-ComparisonThermal Processes-Comparison

Visbreaking Delayed coking Fluid coking

Mild heating at 50-200psi;420-490°C

Reduction in viscosity

Low conversion `10%

Heated coil or drum

Moderate heating at 450-500°C & 90 psig

Soak drums at 450-480°C .Processes continues till complete coking occurs

Coke removed hydraulically

Coke- 20-40 % Yield 30%

Severe heating at 10 psi

450-565°C

Fluid bed with steam

Cracking on fluidized coke

Higher yield of < C5

Less/no coke yield

Fuel grade gas

Page 30: Refinery Structure- Evolution Topping Refinery Hydroskimming Refinery Conversion Refinery Mainly fractionation by distillation For production of industrial.

• Coke-forming tendencies of heavier distillation products are reduced by removal of asphaltenic materials by solvent extraction.

• Liquid propane is a good solvent (butane and pentane are also commonly used).

• Deasphalting is based on solubility of hydrocarbons in propane, i.e. the type of molecule

• Vacuum residue is fed to a countercurrent deasphalting tower. Alkanes dissolve in propane whereas asphaltenic materials (aromatic compounds), ‘coke-precursors’ do not.

• Asphalt is sent for thermal processing.

Propane deasphaltingPropane deasphalting

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Propane deasphalting