distillation of crude

7/31/2019 Distillation of Crude

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DISTILLATION OF

CRUDE

PRESENTED BY:

NITISH SALVI


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ContentsABOUT CRUDE.

DISTILLATION BASICS.

VARIOUS FRACTIONS OF DISTILLATION

COLOUMN.

DETAIL ABOUT FRACTIONS.

SEPERATION.


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Crudeoil


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In crude distillation process, crude oil is first heated

in order to vaporize it and then passed into a

fractionating column in which unvapourised liquid

flows down and out of the bottom as residue while

vapour rise up the column.

In doing so they are contacted with a down flowing

stream of reflux 'on a number of trays filled with

special contacting devices. the tower gets

progressively cooler towards the top & so from the


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various fractions obtained by crude distillation canbe explained as follows:

1.GAS FRACTIONS: NATURAL

GAS,LPG,REFINERY GAS.

2.LIGHT ENDS:

GASOLINE,NAPTHA,KEROSENE.

3.INTERMEDIATE ENDS: FUEL OIL,DIESEL

OIL,GAS OIL,WHITE OIL.

4.HEAVY ENDS:LUBRICATING


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Liquid petroleum gas :

This gas contains

propane & butane & is widely used in

cylinders as domestics fuel or laboratory gas

burners the gas can be easily liquefied &

stored in liquid form. It is very popular as a

cooking gas.


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REFINERY GAS:

This is the off-gas from

refinery operation. it contains a part from

methane & ethane,H2S,H2,SO2 etc.The H2S

content in Indian crude is not much as Indian

crude contains very little sulphur (


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Light fractionsGASOLINE: Commonly known as petrol. it isproduced to a maximum quantity. it is used as a fuelfor automobiles & other light vehicles.

NAPTHA: the term naphtha is refered to thefractions having properties between gasoline &kerosene. It consists of a complex mixture ofhydrocarbon molecules generally having between 5

and 12 carbon atoms. It typically constitutes 1530%of crude oil, by weight. Light naphtha is the fractionboiling between 30 C and 90 C and consists ofmolecules with 56 carbon atoms. Heavy naphtha

boils between 90 C and 200 C and consists ofmolecules with 612 carbons.


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kerosene:

it is the most important constituent of

India. It is used as a household fuel for cooking as well

as for illumination. It is also used as a fuel for jet(its

freezing point must be very low than-25 c) Kerosene

is a thin, clear liquid formed from hydrocarbons, with

a density of 0.780.81 g/cm3, is obtained from the

fractional distillation of petroleum between 150 C


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Intermediate fractionsDiesel oil: these oil which are used in heavy

vehicles such as trucks,buses,locomotives,tractors

etc. have become extremely important. they must be

clean must have good ignition quality for easy

starting of low engine,pressure,good fluidity so that it

does not give much resistance ,to flow but at the


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Fuel oil or furnace oil:

As the name suggest theseare primarily used as fuel in furnace and also inpower station boilers. Nowadays due to shortage ofnaphtha and natural gas they are also used as raw

material for making ammonia and fertilizers.Gas oil:These are used as absorbents for

hydrocarbon gases. This is also used for makingwith tar and asphalt for reducing their viscosity.

Another use is for increasing the calorific value oflow calorific value gases such as producer gasand water gas . Most of it is nowadays used tocrack light fractions.

White oil:

This is primarily used for making hair oil orcosmetics.


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Heavy fractionsLubricating oil:

These include various oils used forlubrication of machinery such as motor,engine,machine,gear

oil etc. the important properties of the lubricating oil areviscosity, flash point.Paraffin wax:

Paraffin wax is used formaking wax paper candles, insulatingmaterials, sealing compounds and ointment.

Mineral jelly:

This is used for making ofcosmetics, sealing compound for preventing leakespecially in acid lines. another use is to apply it


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ResidueAsphalt:

the main use of asphalt is for water proofing ofroofs. it is used in road making and protective coating andinsulating material.

Petroleum coke: coke is used for making carbon electrodesother use of petroleum coke is in manufacture of calcium carbideand black paints.

Grease: these are semisolid mixture of solids they are used forlubrication as well as sealing of moving parts. grease are usedwhere lubrication cannot be done.


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Distillation is a mass transfer separation wherein a mixture containing two or morecomponents can be separated into individualcomponents or group of components using

counter-current multistage liquid-gascontacting equipment.

Ease of separation depends on- feed concentration

- relative volatility of components

SEPERATION:


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Each stage in a distillation column providescontact for gas and liquid.

Section of column above feed point is called

enriching section or rectifying section.

Section below the feed point is called stripping

or exhaustive section.

Liquid to column is provided by reflux while

vapor to the column is provided by reboiler.


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Feed stream provides both liquid and vapor.

Vapours going up and liquid flowing down are

in equilibrium.

Vapours leaving to the column top are rich in

the more volatile components (lighter

components).

The vapours are condensed and part of it is


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In this way, at each stage, vapor leaving the

stage becomes enriched in more volatile

component and liquid leaving the stage

becomes concentrated in less volatilecomponent.

Relative volatility depends on vapor pressure.

For an ideal binar s stem, relative volatilit is


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The relative volatility can be altered by

changing the operating pressure.

Separation becomes easier and easier as

system pressure is lowered.

Lower operating pressure requires big diametercolumn.

Vacuum distillation is preferred when

se aration is difficult or tem eratures are to be


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Factors Affecting

DistillationNumber of trays in a column

Column capacity

Reflux rates to column

Feed Composition


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ABNORMAL OPERATION

FLOODING

ENTRAINMENT

PULSATION

DUMPING

COONING

TRAPPED WATER

HIGH LIQUID LEVELS

DRY TRAYS


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Flooding can berecognized by:

Poor quality products

Small temperature gradient

Pressure drop larger than normal

Pressure fluctuations


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Intermittent flow of vapor through slots of

bubble caps.

Causes low tray efficiency.

Depends on physical properties of the two

phases, cap construction and tray layout.

Pulsation


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Dumping

High liquid loads causes liquid to enter the gapand fall through risers.

Reduces efficiency of column.Can be avoided by preventing the liquid from

entering the slots at high velocity.


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High Liquid Levels

Trays behave as if they are flooded.

Efficiency of fractionation reduces.

Height of liquid level is controlled byadjusting flow rate of bottom product.


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Distillation Column

ControlTwo main variables to be controlled are

:-

Reflux ratio

Heat supplied to the column


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THANK

YOU

distillation of crude

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