petroleum refining

1. Wax Processing and
Purification

2. The word "wax" usually refers to a variety of organic
substances that are solid at ambient temperature but become
free-flowing liquids at slightly higher temperatures.
The chemical composition of waxes is complex, but normal
alkanes are always present in high proportion and molecular
weight profiles tend to be wide.
According to the chemical composition waxes are basically
esters of long chain fatty acids and long chain monohydric or
polyhydric alcohols, each containing 16-34 carbon atoms(C
atoms).
Introduction

3. Naturally they are produced by plants and animals
and also found in petroleum.
Their melting point ranges from 35-100 degree
centigrade.
They are soluble in organic solvents and in-soluble in
water.
In general, these are found in nature as a mixture of
esters.
So we can say that :
“Waxes are the mixed esters of higher monohydric
or polyhydric alcohols other than glycerol with fatty
acids”.

4. Classification of waxes
Waxes can be classified as Natural and Synthetic
1. Natural Waxes
Animal Waxes
Vegetable waxes
Mineral waxes

5. Mineral waxes
Mineral waxes are paraffin waxes which are obtained from petroleum.
For example:
Paraffin wax - made of long-chain alkane hydrocarbons
Microcrystalline wax - with very fine crystalline structure
Petroleum jelly-Petrolatum or petroleum jelly is essentially a mixture
of microcrystalline wax and oil.
Ceresin waxes -wax like the paraffin consists of a group of
hydrocarbons relates to methane with low acid number so that it's
important in rubber compounding.
Mountain wax - extracted from lignite and brown coal
Ozocerite - found in lignite beds
Peat waxes-dark waxy substance extracted from peat using organic
solvents.

6. Paraffin wax
Paraffin wax refers to a mixture of alkanes that falls within the 20 ≤
n ≤ 40 range; they are found in the solid state at room temperature
and begin to enter the liquid phase past approximately 37°C.
Paraffin wax is a mixture of saturated aliphatic hydrocarbons (with
the general formula CnH2n+2). Pure paraffin wax is an excellent
electrical insulator, with an electrical resistivity of between 1013 and
1017 ohm meter.
Microcrystalline waxes
Microcrystalline waxes are a type of wax produced by de-oiling
petrolatum, as part of the petroleum refining process. In contrast to
the more familiar paraffin wax which contains mostly unbranched
alkanes, microcrystalline wax contains a higher percentage of
isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons

7. Petrolatum
Petrolatum is usually a soft product containing approximately 20%
oil and melting between 38°C (100°F) and 60°C (140°F). Petrolatum
or petroleum jelly is essentially a mixture of microcrystalline wax
and oil.
It is produced as an intermediate product in the refining of
microcrystalline wax or compounded by blending appropriate waxy
products and oils.
Petrolatum colors range from the almost black crude form to the
highly refined yellow and white pharmaceutical grades.

8. Synthetic Waxes
Synthetic waxes are produced primarily from ethylene. These
materials are less variable than natural products and less inclined to
price fluctuations since supply is not dependent on weather, rain fall
etc. which can affect Carnauba production.
Polyethylene waxes
Polypropylene wax
Tetrafluoroethylen (PTFE)
Ethylene-Acrylic Acid (EAA)

9. Polyethylene waxes
Polyethylene waxes are manufactured from ethylene which is
generally produced from natural gas.
Polypropylene wax
Polypropylene wax is generally polymerized from propylene and then
either maleated or oxidized to give chemical functionality so that it is
more easily emulsified.
Tetrafluoroethylen (PTFE)
PTFE is a fluorocarbon polymer. The fluorine component gives this
product additional release, slip and rubs characteristics.
Ethylene-AcrylicAcid (EAA)
EAA co-polymer properties are more resin like than wax. These
polymers have high 20% acrylic acid content. These products are high
molecular weight with excellent adhesion to a wide range of
substrates.

10. Physical Properties of waxes
Melting point, boiling point and melt viscosity
The melting point of n-alkanes increases with molecular weight.
Over the carbon atom number range from C1 to C25
relationship between the melting point and the carbon atom
number cannot be described with one single function for even-
numbered and odd-numbered n-alkanes, i.e. the melting points
are higher and lower, respectively, than the average values
calculated from even- and odd numbered n-alkane melting
points.

12. Density and thermal expansion
The density of paraffin waxes increases with their melting point
increases
Table . Densities of microcrystalline paraffin waxes having different
melting points

13. Optical properties
The refractive index is a physical property frequently used for identifying
substances and for determining their compositions. The refractive index of
paraffin waxes is usually measured at 80 to 85 oC. The refractive indices of
microcrystalline paraffin waxes at 84 oC vary between 1.4210 and 1.4315, their
molar refraction between 100 and 154.
Water vapor permeability
In the manufacture of packaging materials, paraffin waxes are chiefly used to
reduce water vapor permeability of paper. This is valid for both coating and
laminating waxes, the latter being often applied for the sake of the low vapor
permeability of the paraffin wax film.
Water resistance
Water and aqueous solutions come into direct contact with waxed paperboard
used for containers of deep-frozen food, milk cartons, paper cups, etc.
Therefore, resistance to water is an important requirement in those applications
where no water must be allowed to penetrate through the paraffin wax film.
Resistance to water of lower-melting microcrystalline paraffin waxes is
superior to that of microcrystalline refined waxes. This difference is
presumably due to the denser crystal structure

14. An important operation in the production of lubricating oils is the
dewaxing of the corresponding petroleum fractions and residues,
since it is only possible to manufacture lubricating and industrial
oils with low pour points and with viscosities, suitable for use at
low temperatures, from crudes containing paraffin. The
manufacture of petroleum waxes includes the following
technological processes :
Production of slack waxes and petrolatum's by dewaxing
petroleum products.
De-oiling and fractional crystallization of slack waxes and
petrolatum's.
Purification of crude paraffin waxes.
Blending of paraffin waxes with additives.

15. Dewaxing Processes
Dewaxing is important from two points of view:
 producing products with suitable pour points from waxy feedstock.
particularly in the case of higher average molecular weight petroleum
distillates and distillation residues no sharp dividing line can be drawn
between the hydrocarbons forming solid paraffins and those that cannot
be considered as solid.
Dewaxing Operation

16. Dewaxing Crystallizer
1. Large and well-developed crystals can be readily pressed and
filtered.
2. The needle-shaped crystalline types can be easily sweated
3. Microcrystalline paraffin waxes cannot be separated by filter
pressing, but are readily separated by centrifuging.
Dewaxing processes using solvents
In these processes, organic solvents are used as diluents which, at
the temperature of filtering, dissolve paraffin waxes only to a very
slight extent, while they are good for dissolving the other
components of lubricating oils. Rotary filters are mostly used to
separate crystallized paraffin wax.
Dewaxing Processes Methods

17. 1. Methyl ethyl ketone dewaxing
2. The propane dewaxing process
3. Dewaxing with a mixture of propylene and acetone
4. Dewaxing with chlorinated hydrocarbons
5. Dilchill dewaxing process
6. Filter aids

18. De-oiling and fractional crystallization of slack
waxes and petrolatums
Oil and low-melting fractions removed from the slack wax. The
process is called de-oiling.
De-oiling is fractional crystallization of slack or paraffin waxes
by their melting point.
Slack waxes obtained from light distillates by cooling and
pressing were formerly-oiled exclusively by a
process called sweating.

19. Slack Wax, feedstock, is obtained from the dewaxing of refined
or unrefined vacuum distillate fractions. If the material has been
separated from residual oil fractions it is frequently called
Petrolatum.
The slack waxes are de-oiled by sweating processes to produce
commercial waxes with low oil content. The oil that is
separated from these processes is known as Foot Oil. The
refined petroleum waxes are known as Paraffine Waxes.
Microcrystalline Waxes have higher molecular weight than the
paraffine waxes and consist of substantial amounts of iso and
cycloalkanes.

20. ■ PARAFFINE WAX
A waxy crystalline substance that in the pure form is white, odorless and
translucent and has the approximate chemical formula of C20H42 (and above). It
is obtained from petroleum by distillation and is then purified by sweating or
solvent refining. Paraffin, which is not a true wax, consists mainly of a mixture
of saturated straight-chain solid hydrocarbons. Its melting points range from
50°C to 57°C.
■ MICROCRYSTALLINE WAX
Microcrystalline waxes consist of odorless, tasteless, non-polar hydrocarbons
with relatively high melting points. Multi wax grades vary in color from white to
yellow, and in such physical properties as hardness and melting point.
■ VASELINE (PETROLEUM JELLY)
Vaseline is a well-known brand of petrolatum (Petroleum Jelly). Petrolatum is a
flammable, semi-solid mixture of hydrocarbons, having a melting-point usually
ranging from a little below to a few degrees above 37°C. It is colorless or of a
pale yellow color, translucent and devoid of taste and smell.

22. PROCESS FLOW DESCRIPTION - I
Paraffin Wax & Microcrystalline Wax
The slack wax, as by-product, is obtained in the lube oil process of
the refinery plant. Slack wax is a mixture of oil and wax, which
serves as the wax industry's feedstock and that is further refined and
blended to create value-added petroleum wax products.

23. SWEATING PROCESS
The sweating chamber, a steel structure covered with insulation, contains rectangular
trays with cone shape bottom, which are equipped with approx. 50 mesh screen plate in
its lower part and coils for alternate cooling and heating purpose. These trays are
installed inside of the sweating chamber by an arrangement of several vertical lines of
which each has approx. 8 ~10 trays.
In the first step of this process, the fresh water is filled in each tray until the level
reaches slightly over the screen mesh before the feed wax feeds to keep 10 ~ 20 cm
thick beds and then the cooling water is circulated through the coil. After the feed is
completely crystallized, the filled water is drained off.
The crystallized wax is then sweated while simultaneously draining the liquid
drippings, so called foot oil, from each tray in the sweating chamber. The later fractions
of foot oil is recycled through sweating process.

24. When the congealing point of the liquid drippings indicates that
melting temperature of desired wax product has been obtained,
sweating and drainage are stopped. Consequently, the remaining
solid bed of wax in the sweating chamber is rapidly melted by
heater and then flows to semi-finished product tanks.
To produce refined wax from a product wax requires that the
wax should be treated with activated clay for color and odor
removal is filtered in filter press or rotary drum filter. In order to
obtain the low oil content required in final wax products,
sometimes two or three repeated treatments are required.

25. Process Flow Diagram (Wax-Sweating Process)

26. PROCESS FLOW DESCRIPTION - II
Vaseline (Petroleum Jelly)
In the process, either petrolatum and lube base oil from oil refinery or
paraffin and micro wax produced from the sweating process as
described are used as feedstock.
The process, as semi-continuous process, can be divided either by the
blending ratios of the feedstock or treatment methods.
ACID TREATMENT PROCESS
The feedstock from storage tanks are exactly
pre-measured in proportion to each required
fraction and then transferred by metering
pumps to the acid treatment tank where they
are blended and mixed to give certain desired
properties such as melt point and penetration.

27. After the transfer is completed, the blended is mixed and heated up to 80 ± 5
°C by hot water through heating coils equipped within the tank.
In case the blended meets the targeted qualities by sampling check, it proceeds
to the next stage acid treatment. The sulfuric acid (H2SO4) solution with
concentration of approx. 0.5 wt % is gradually injected into the tank with
maintaining the pre-conditioned temperature and blending. In the reaction with
sulfuric acid, most of traces of aromatics, resins and impurities are removed.
As a form of finishing process, the treatment of the molten wax with activated
earth (Clay) to neutralize acidity remaining from earlier sulphuric acid
treatment and/or to improve color and reduce odor and taste of the finished
wax, also to remove traces of possibly harmful compounds (Polycyclic
Aromatic Hydrocarbons). In the next filtration, the finishing product is filtered
in filter press or rotary drum filter.
This earth treatment may be repeated several times until the product meets the
requirement of color and neutralization

28. Process Flow Diagram (Vaseline-Acid Treatment Process)

29. FEEDSTOCK PROPERTIES
Table
Slack Wax;
Generic term for the mixture of wax and oil recovered in a
dewaxing process; may contain 2 ~ 35% oil.
Typical dispositions are to further process for finished wax,
to process for fuels or to sell into certain end-use markets.

30. Physical Properties of Slack Wax
* The above is a typical specification of the feedstock, which have
been used as main raw materials.

31. END PRODUCTS
The following specifications of the end products are typical, which can be
varied in accordance with code or standard applied in the countries.
All values are taken on samples of one batch and the specification may vary
from batch to batch.
Specification of Microcrystalline Wax

32. Specification of Refined Paraffin Wax

33. Specification of Petroleum Jelly(white)

34. APPLICATIONS

35. Purification of Waxes
The purity of paraffin waxes is an important aspect in their grading.
The required extent of purity, obviously, depends on the type of the
field of application. Paraffin waxes used for candle manufacture, for
instance, must be white and stable to color changes.
Paraffin waxes applied in food conservation and packaging must be
odorless and free from compounds damaging the human organism,
above all from polycyclic aromatic substances. Similar, but even
more strict specifications are applied for paraffin products to be used
for medical purposes.
purification processes based on
1. Treatment with chemicals
2. Adsorption
3. Hydrogenation.

36. It is a common feature of all chemical purification processes that
to achieve the desired grade, rather vigorous conditions have to
be used.
The agents include potassium hydroxide, sodium hydroxide,
sodium carbonate, ammonia, alkaline solution of magnesia, zinc
oxide.
In this process, among many other intermediate reactions,
oxidation, condensation, polymerization, sulfonation and resin-
forming take place. The final effect of the purification depends
on the composition of the initial product.
By treatment with chemicals

37. The simplest process, essentially purification by adsorption, is by
mixing with bleaching earth.
After a satisfactory contact time, i.e. after equilibrium has been
established, the paraffin wax is separated by filtration and the used
bleaching earth is discarded.
Various types of fuller’s earth activated carbon, silica gel, bauxites,
betonies, natural or synthetic aluminum silicates are suitable
adsorbents.
By adsorption processes

38. The essence of all refining hydrogenation processes can be
summarized as follows :
1. A suitable mixture of the feedstock and hydrogen is heated to
the required reaction temperature.
2. The gas-phase or liquid-phase or gas-liquid phase reaction
mixture enters the reactor packed with catalyst where the desired
reactions and side reactions proceed.
3. The contents of the reactor are cooled, the hydrogen-rich gas
phase is separated in a high-pressure separator, hydrogen sulfide
formed in the reactions is removed and the gas is recycled into the
process.
4. After reduction of pressure, the gases dissolved in the liquid
reaction product are removed by flash distillation
By hydrogenation

39. Blending of paraffin waxes
Paraffin waxes in their various fields of application require many
different specifications. These can only partly be satisfied by a
suitable choice of feedstock and the above-discussed
manufacturing processes, or even by some modifications of these
processes. In order to fully meet the great variety of demands,
and to further increase the assortment of paraffin wax grades,
manufacturers resort to blending.
The two groups used as additives to paraffin waxes are
1. microcrystalline paraffin waxes
2. polymers

40. Tests and application
of Waxes

41. Colour
Paraffin wax is generally white in color, whereas microcrystalline
wax and petrolatum range from white to almost black. A fully
refined wax should be virtually colorless when examined in the
molten state. Absence of color is of particular importance in wax
used for pharmaceutical purposes or for the manufacture of food
wrappings..

42. TEST
• The test method for the color of petroleum products is
used for wax and petrolatum that are too dark for the
Saybolt colorimeter.
• A liquid sample is placed in the test container, a glass
cylinder of 30- to 35-mm ID, and compared with
colored glass disks ranging in value from 0.5 to 8.0 by
using a standard light source.
• If an exact match is not found, and the sample color
falls between two standard colors, the higher of the
two colors is reported.

43. Density
• Density is an important property of petroleum products because
petroleum and especially petroleum products are usually bought
and sold on that basis or, if on a volume basis, then converted to a
mass basis via density measurements.
• For clarification, it is necessary to understand the basic definitions
that are used:
 Density is the mass of liquid per unit volume at 15°C
 Relative density is the ratio of the density of liquid at 15°C to
the density of pure water at the same temperature
 specific gravity is the same as the relative density, and the
terms a are used interchangeably

44. Test
• To determines density and specific gravity by means
of a digital densimeter. In the test, a small volume
(approxi- mately 0.7 ml) of liquid sample is
introduced into an oscillating sample tube and the
change in oscillating frequency caused by the change
in the mass of the tube is used in conjunction with
calibration data to determine the density of the sample.

45. Melting point
 The melting point is one of the most widely used tests to determine the quality and
type of wax.
 Due to the individual hydrocarbons does not melt at sharply defined temperatures
because it is a mixture of hydrocarbons with different melting points but usually
has a narrow melting range.
Table Melting Point of Pure n-Hydrocarbons
• Number of C Atoms Melting Point °C Number of C Atoms Melting Point °C
• 9 -54 28 61
• 10 -30 29 64
• 11 -26 30 66
• 12 -10 31 68
• 13 -5 32 70
• 14 6 33 71
• 15 10 34 73
• 16 18 35 75
• 17 22 40 82
• 18 28 50 92
• 19 32 60 99
•

46. Test
• Method 1 :In the method , a molten wax specimen is placed in a test tube
fitted with a thermometer and placed in an air bath, which in turn is
surrounded by a water bath held at 16–28°C (60–80°F). As the molten wax
cools, periodic readings of its temperature are taken. When solidification of
the wax occurs, the rate of temperature change decreases, and draw the
cooling curve. The temperature at that point is recorded as the melting point
of the sample.
• Method 2: Drop melting point of wax , in this method samples are
deposited on the two thermometer bulbs by chipping chilled thermometer
into the sample. By heating when drop falls from thermometer temperature
is checked and this point s drop melting point.

47. Odor and Taste Test
• The odor of wax is an important property in some uses of wax
such as food packaging and is often included in the
specifications of petroleum wax. But wax is a colorless.
• Odor Test
• The odor of petroleum wax is determined by a method in
which 10 g of wax is shaved, placed in an odor-free glass
bottle, and capped. After 15 min the sample is evaluated in an
odor-free room by removing the cap and sniffing lightly.
• Taste
• A specific example is wine tasting

48. Viscosity
 Viscosity of molten wax is of importance in applications
involving coating or dipping processes because it influences the
quality of coating obtained.
 paper converting, hot dip anticorrosion coatings, and taper
manufacturing.
Test
 Kinematic viscosity is measured by timing the flow of a
fixed volume of material through a calibrated capillary at
a selected temperature . The unit of kinematic viscosity is
the stokes, and kinematic viscosities of waxes are usually
reported in centistokes.
 By viscometer its viscosity can be measured.

49. Applications of waxes
• They are many uses in
 Pharmaceuticals
 Cosmetics
 plastics
 textiles
 foods
 Corrugated board

50. Suitable Ingredients for
 Polishes
 Paste types , used for
i. Floors
ii. Furniture
iii. Cars
iv. footwear

51. Waxes are also used for
 candle making

52.  Coatings for waxed paper or cloth.
 Food-grade paraffin wax
 Food packing industry is the largest consumer of wax today
 Coating of fruit and cheese
 For lining of cans and barrels
 Manufacturing of anti-corrosives
 Due to thermoplastic nature used for molding and making of
replicas
 Blends of waxes are used for dentists when making dentures
 Used engineers when mass-producing precision casting
 Shiny coating used in candy -makingalthough edible

53.  Coating for many kinds of hard cheese, like Edam cheese
 Sealant for jars, cans, and bottle
 Solid propellant for hybrid rocket motors
 Component of surf wax, used for grip on surfboards in surfing
 Component of glide wax, used on skis and snowboards.
 Bone wax is used to help mechanically control bleeding from
bone surfaces during surgical procedures

54. Chewing gum additive
Friction-reducer, for use on handrails and cement ledges,
commonly used in skateboarding .
Ink. Used as the basis for solid ink different color blocks of
wax for thermal printers. The wax is melted and then sprayed
on the paper producing images with a shiny surface.
 Thickening agent in many Paintballs, as used by Crayola.
 Wax baths for beauty and therapy purposes .
 Micro wax: food additive, a glazing agent.

55. Asphalt is a sticky, black and highly viscous liquid or semi-solid form
of petroleum.
• It may be found in natural deposits or may be a refined product.
Asphalts are obtained by the oxidation of residual heavy oil in air at
higher temperature and vacuum distillation.
Asphalt has high viscosity, occur in semi- solid forms. It is used for
road –making and water proofs
Asphalts

56. Petroleum-Based Asphalts
 Asphalt is waste product from refinery processing
of crude oil
 Sometimes called the “bottom of the barrel”
 Properties depend on:
 Refinery operations
 Composition crude source-dependent
Gasoline
Kerosene
Lt. Gas Oil
Diesel
Motor Oils
Asphalt
Barrel of Crude Oil

57. Composition of Asphalt
 Oil-35 to 50%
 Resins – 5 to 20%
 Asphaltenes- 20 to 30%
 Acids- Up to 10%

58. Asphalt Cement Components
 Asphaltenes
 Large, discrete solid inclusions (black)
 High viscosity component
 Resins
 Semi-solid or solid at room temperature
 Fluid when heated
 Brittle when cold
 Oils
 Colorless liquid
 Soluble in most solvents
 Allows asphalt to flow

59. Refinery Operation
FIELD STORAGE
PUMPING
STATION
LIGHT DISTILLATE
HEAVY DISTILLATE
PROCESS
UNIT
ASPHALT
CEMENTS
FOR PROCESSING INTO
EMULSIFIED AND
CUTBACK ASPHALTS
STILL
AIR
AIR
BLOWN
ASPHALT
STORAGE
TOWER
DISTILLATION
REFINERY
RESIDUUM
OR
GAS
PETROLEUM
SAND AND WATER
CONDENSERS
AND
COOLERS
TUBE
HEATER
MEDIUM DISTILLATE

60. Types
 Asphalt cements
 Generally refinery produced material
 Air blown asphalt cements
 Cutbacks
 Asphalt cements “cut” with petroleum solvents
 Emulsions
 Mixture of asphalt cement, water, and emulsifying
agent

61. Air Blown Asphalt Cement

62. Asphalt Air Blowing Process
The physical properties of asphalts may further be modified by 'air
blowing'. This is an oxidation process which involves the blowing of air
through the asphalts, either on a batch or a continuous basis, with the
short residue at a temperature of 240°C to 320°C.
This process is used to increase the viscosity of the resid to produce
products such as roofing asphalts.
Air blowing combines oxygen with hydrogen in the asphalt, producing
water vapor. This decreases saturation and increases cross-linking within
or between different asphalt molecules.
Oxidation hardening of the asphalt cement due to air being continually
injected results in a large increase in viscosity.
This process can also be used to reduce the temperature susceptibility of
a paving-grade asphalt cement.