4. CONTENTS
Refinery
Separation Process
Crude oil
Types of crude oil
Distillation
Distillation column
Atmospheric distillation
Components of column
Types of column
Trays and packing's
Vacuum distillation
How vacuum created
Uses of distillation products
Steps in distillation
Other types of distillation
Factors affecting distillation operation
Vapors flow rates
5. REFINERY
A set of equipment's used for making various
Useful Products by processing Crude Oil (Which
directly cannot be used as a beneficial product).
ARL receives crude from 80-85 different oil fields
throughout Pakistan
Crude is received through Pipeline as well as
Bowsers to Refinery
After receiving, blends of different fields are
prepared in respective tanks so that a proper
crude may be charged to respective plant. e.g. a
heavy density blend is charged to the heavy
crude distillation unit
8. SEPARATION PROCESS
A process that converts a mixture of substances
into two or more distinct product mixtures (which
may be referred to as fractions), which differ from
each other in composition.
9. SEPARATION PROCESS
Generally, separation processes may be classified
as either mechanical-physical separation processes
or mass transfer operations.
Mechanical-physical separation processes (do not
require a mass transfer gradient for the
separation)
Mass transfer operations (based on diffusion and
require a mass transfer gradient for the
separation)
11. Examples of mass transfer operations are:
Distillation
Drying
Liquid-liquid extraction
Leaching
12. HYDRO-CARBONS
Chemical compounds which consist of Hydrogen &
Carbon essentially. Other elements like Oxygen,
Nitrogen, Sulfur and some metals may also be
present.
Crude oil contains various kinds of hydro carbons.
13. CRUDE OIL
A mixture of various hydrocarbons formed by
Decay and Decomposition of animals as well as
forest plants under Earth crust at High Pressure
and Temperature millions of years ago
Crude oil contains hundreds of different
hydrocarbons, present in different proportions &
compositions
Crude oil also contains small quantities of water
and salts depending on the source from where it
is extracted
Impurities include salts of Ca & Mg, sand,
drilling mud, iron oxide, leaves, trashes, water
and sulfur
15. TYPES OF CRUDE (W.R.T DENSITY)
Light Crude:
Crude having Specific gravity (Rel.
density) less than 0.86 or which contains more
quantity of lighter fractions.
Heavy Crude:
Crude having Specific gravity 0.86 or
greater is called heavy crude or which contains
more heavier fractions.
16. TYPES OF CRUDE (W.R.T. SULFUR)
Sweet Crude:
The Crude having sulfur contents less
than 0.5wt %.
Sour Crude:
Crude having sulfur contents 0.5wt %
or more.
17. DISTILLATION
Distillation is a Separation technique in Unit
Operations, in which a mixture is separated into
various components due to difference in their
boiling point/ Relative Volatility by application of
heat.
The Separation Technique in Unit operations
which leads to “ Partial Vaporization & Partial
Condensation”
No Chemical Reaction in Distillation, only physical
separation.
18. What is Partial Condensation and Vaporization?
Suppose we have a mixture of 50% pentane (B.P
36 C)& 50% hexane (B.P 69 C) in a close
container. Now we want to separate it out.
So for separation, we have to first maintain temp
of vessel at 36 C. At this temp, all pentane will
vaporize and collect at receiver, while all hexanes
remain in vessel. So we have separate these
hydrocarbons.
This is called Partial condensation & Partial
vaporization
19. Equipments used in small scale distillation are:
A Still having a reboiler or pot in which the
source material is heated
A Condenser in which the heated vapors is cooled
back to the liquid state
A Receiver in which the concentrated or purified
liquid is collected
21. WHAT IS DISTILLATION COLUMN?
A tower consisting of Trays in which liquid and
vapors contact, mass transfer occurs and mixture
is divided into its components physically
The Hot Feed enters the Flash zone of distillation
column
The heavy oil like furnace or bitumen which
remain in liquid form, go to the bottom of tower,
while the lighter molecules travel towards top as
these are in vapor form
22. ATMOSPHERIC DISTILLATION
Distillation generally occur at a pressure greater
than atmospheric pressure. This may be done for
pressure drop considerations, to flow the vapors
from one location to the desired location
Desalted crude oil is flashed in the atmospheric
distillation unit and the crude oil is fractionated
into various fractions
Light gases, light and heavy naphtha, kerosene,
light and heavy gas oils, and atmospheric residue
23. COMPONENTS OF COLUMN
Vertical Shell where the separation of liquid
components is carried out
Trays/Plates column internals such as
trays/plates or packing's at which vapor liquid
contact/mass transfer takes place
Re-boiler to provide the necessary vaporization
for the distillation process
Condenser to cool and condense the vapor
leaving the top of the column
Reflux drum to hold the condensed vapor from
the top of the column so that liquid (reflux) can
be recycled back to the column
25. REFLUX
Reflux refers to the portion of the condensed
overhead liquid product from a distillation or
fractionation tower that is returned to the upper
part of the tower
Maintain the proper temperature profile in the
column
Maintain the purity of the fractions
Maintain the proper specifications of the
products
29. TYPES OF COLUMN
Tray column - where trays of various designs are
used to hold up the liquid to provide better contact
between vapor and liquid, hence better separation.
Packed column - where instead of trays,
packing's are used to enhance contact between
vapor and liquid
33. VALVE TRAY
Lift able caps
Vapor flows lifts the caps
Provide better mixing
34. SIEVE TRAYS
Simply Metal Plates with holes
Less Pressure Drop
Ease Of Maintenance
Low Cost
35. STRIPPER
To remove the lighter ends from the side
products by adding steam
To maintain the product purity
Product is then pumped, exchange the heat and
then stored in the tank
37. STRIPPING
(REMOVING LIGHTER ENDS FROM BOTTOM / SIDE
PRODUCTS)
The bottom product is not pure and may contain
some lighter ends
Removal of these lighter molecules from product
is necessary
Steam contacts with down coming product like
Furnace oil, kerosene etc. and vaporize the
lighter molecules trapped in it.
38.
39. The fractionators' bottom product is used for two
purposes:
Some Residue, as it is sent to storage after
cooling through feed exchangers and called as
Furnace oil.
Some residue send to Vacuum Tower after
heating in a heater for making Bitumen.
Some lighter ends remain in bottom residue,
because efficiency of any process be never 100%.
So these are removed in vacuum section.
40. Some compounds have very high boiling points. To
boil such compounds, it is often better to lower the
pressure at which such compounds are boiled
instead of increasing the temperature.
So we need Vacuum Distillation
41. VACUUM DISTILLATION
In vacuum distillation, pressure in the column is
less than atmospheric pressure
Decreasing pressure of a component decreases
the boiling point and vice versa
Atmospheric residue is the feed and vacuum gas
oil and vacuum residue may be the products
Pressure less than the surroundings is Vacuum
42. HOW IS VACUUM CREATED
Pressurized steam passes through ejectors.
An ejector has a nozzle, through which steam
passes with its highest velocity.
A process line is attached to this high velocity
point.
Hence the high velocity steam carry process
vapors with it and produces vacuum behind its
system
46. ADVANTAGES OF VACUUM
Energy saved as less fuel is required for a lower
Temperature
As vapors forms easily, so overhead diesel and
other products are recovered in this way
Crude does not crack thermally (mean if no
vacuum, then high temp required, crude may
crack thermally)
47. USES OF DISTILLATION PRODUCTS
Naphtha:
Used as Motor fuel
LPG:
Used as domestic fuel
Kerosene:
Used as Domestic heater fuel, Jet fuel.
MTT: (Mineral Turpentine Oil)
Paints of homes/offices is done by mixing of
MTT with Paint
JP-1/JP-8:
Used as jet fuel
48. Diesel
Used as fuel in cars and heavy Automobiles
JBO:
Used for making Jute batches in jute industry
Also used for making lubricating oils
Furnace oil:
Used as fuel in Power Plant Generators
Bitumen/Asphalt:
One of the Raw material in Road making
49.
50. STEPS IN DISTILLATION UNITS
1. 1st Pre-heat train of heat exchangers
2. De-salters
3. Charge Heater
4. Distillation Tower
5. Stabilizer section
6. Vacuum Distillation (in case of heavy
crude)
7. Product cooling
52. STEAM DISTILLATION
Steam distillation is a method for distilling compounds
which are heat-sensitive.
High rate of heat transfer without heating at a very high
temperature.
This process involves bubbling steam through a heated
mixture of the raw material.
Some of the target compound will vaporize (in accordance
with its partial pressure).
The vapor mixture is cooled and condensed, usually
yielding a layer of oil and a layer of water
Extractive distillation
Reactive distillation, etc.
54. REFLUX
It is necessary to remove heat from some parts of
tower to control the temperature as well as
pressure of tower, this is actually controlling the
quality of different products
A line from tower goes directly to a pump, then
through pump, it passes through cold crude
(Feed) exchangers, transfer its heat to crude and
then send back to column
When up-coming vapors in tower come in contact
with that plate, the desired components condense
and can be extracted as a product
Hence the temp & quality is achieved.
Without reflux, the product will be too heavy or
off grade
55. Inside the tower, the down flowing reflux liquid
provides cooling and condensation of the up
flowing vapors thereby increasing the efficiency
of the distillation tower
More reflux that is provided for a given number
of plates the better the tower's separation
Alternatively, the more reflux that is provided for
a given desired separation, the fewer the number
of plates required
56. SOME IMPORTANT RELATIONS
Tower Top Temperature α End Point of Product
Tower Top Temperature α IBP of Product
Tower Top Temperature α 1/External Reflux
(Cold Reflux)
With Draw Flow Rate of Product α End Point
58. FOAMING
Expansion of liquid due to passage of vapor
Provides high interfacial liquid-vapor contact
Depends upon properties of liquid mixtures
Separation efficiency is reduced
59. ENTRAINMENT
Liquid carried by vapor up to the tray caused by
high vapor flow rates
Efficiency is reduced
Excessive entrainment can lead to flooding
60. WEEPING
Caused by low vapor flow
Insufficient pressure exerted by the vapor to
hold up the liquid on the tray
Liquid starts to leak through holes
Excessive weeping will lead to dumping
Indicated by a sharp pressure drop in the column
Reduced separation efficiency
61. FLOODING
Excessive vapor flow
Liquid to be entrained in the vapor up the
column
Flooding is detected by sharp increases in column
differential pressure
Significant decrease in separation efficiency.
