Summer Training report of Petroleum Refinery Processes done in Engineers India Limited, Gurgaon

1. SUMMER TRAINING REPORT ON
“REFINERY PROCESSES AND SIZING OF EQUIPMENTS”
FOR THE DURATION 01-07-2019 TO 26-07-2019
SUBMITTED TO –
ENGINEERS INDIA LTD. (EIL)
SUBMITTED BY –
ARCHIT TODI
CHEMICAL ENGINEERING DEPARTMENT
ASSAM ENGINEERING COLLEGE
JALUKBARI, GUWAHATI-781013

2. PREFACE
Vocational Training plays a vital role in the progress of future engineers. Not
only does it provide insights about the company concerned, but it also bridges
the gap between theory and practical knowledge. I was fortunate that I was
provided with an opportunity of going vocational training at Engineer’s India
Ltd., Gurugram. The experience gained during this short period was fascinating
to say the least. It was a tremendous feeling to observe the undergoing projects
and know the role of a designing Company in any project. In the duration of my
training I realized that in order to be a successful Chemical Engineer one needs
to possess a sound theoretical base along with the acumen for effective practical
application of theory. Thus, I hope that this industrial training serves as a
stepping stone for me in future and help me carve a niche for myself in this
field.

3. ACKNOWLEDGEMENT
The internship opportunity I had with “Engineers India Limited, Gurugram”
was a great chance for learning and professional development. Therefore, I
consider myself as a very lucky individual as I was provided with an
opportunity to be a part of it. I am also grateful for having a chance to meet so
many wonderful people and professionals who led me though this internship
period.
I express my deepest thanks to Ramakrishna Sir, for taking part in useful
decision & giving necessary advices and guidance and arranged all facilities to
make my training easier. I choose this moment to acknowledge his contribution
gratefully.
Bearing in mind previous I am using this opportunity to express my deepest
gratitude and special thanks to Mr. Kulwinder Singh Sir and Ms. Apoorva
Yuvraj Mam who in spite of being busy with his/her duties, took time out to
hear, guide and keep me on the correct path and allowing me to carry out my
project during the training.
It is my radiant sentiment to place on record my best regards, deepest sense of
gratitude to Ms. Neha Shukla Mam for her careful and precious guidance in my
vocational training.
I perceive this opportunity as a big milestone in my career development. I will
strive to use gained skills and knowledge in the best possible way, and I will
continue to work on their improvement, in order to attain desired career
objectives. Hope to continue cooperation with all of you in the future.

4. INDEX
SL NO. CONTENTS PAGE
1. COMPANY PROFILE
 ABOUT THE COMPANY
 AREAS OF EXPERTISE
 MISSON & VISION
 MAJOR PROJECTS
2. INTRODUCTION TO REFINING
 WHAT ARE REFINERIES?
 WHY DO WE REFINE?
 CRUDE OIL CHARACTERISTICS
 PETROLEUM PRODUCTS
3. OVERVIEW OF REFINING OPERATIONS
 BLOCK FLOW DIAGRAM
 DESALTER
 CDU
 VDU
 HYDROTREATING
 VGO HYDROTREATING UNIT
 FCCU
 COKER (VISBRAKER)
 HYDROCRACKER
 CATALYTIC REFORMER
 ISOMERIZATION & ALKYLATION
 SRU, ARU, SWS
 HYDROGEN MANUFACTURING UNIT
 MEROX TREATMENT
 BITUMEN BLOWING
 NEEDLE COKE UNIT

5. 1. COMPANY PROFILE
ABOUT THE COMPANY
Engineers India Ltd (EIL) is one of India’s leading global engineering
consultancy and EPC Company. Established in 1965, EIL provides engineering
consultancy and EPC services principally focused on the oil & gas and
petrochemical industries. The Company has also diversified into sectors like
infrastructure, water and waste management, solar & nuclear power and
fertilizers to leverage its strong technical competencies and track record. It also
provides specialist services such as heat and mass transfer equipment design,
environmental engineering, specialist materials and maintenance and plant
operations and safety services.
Today, EIL is a ‘Total Solutions’ engineering consultancy company providing
design, engineering, procurement, construction and integrated project
management services from ‘Concept to Commissioning’ with highest quality
and safety standards. EIL’s QMS, OHSMS and EMS are certified to ISO 9001,
OHSAS 18001 and ISO 14001 respectively.
With corporate office in New Delhi, EIL also operates from its office in
Gurugram, branch office in Mumbai, three regional engineering offices in
Kolkata, Chennai & Vadodara and has inspection offices at all major
manufacturing locations of the country. The company’s overseas presence is
marked by an engineering office in Abu Dhabi, which caters to the business
needs in UAE/Middle-East region. Additionally, there are offices in London,
Milan and Shanghai to coordinate the activities of international procurement
and marketing.
EIL’s technological excellence is driven by over 2300 competent and dedicated
team of professionals and technical workforce with In-house and collaborative

6. R&D support with 26 registered patents and 22 pending patent applications. The
availability of technical resources per annum is about 4.6 million man-
hours in EIL’s design offices along with 1.19 million man-hours of construction
management services annually. EIL has to its credit more than 6000
assignments including over 500 major projects successfully completed and
operating smoothly, in many cases at more than rated capacity, creating an array
of satisfied clients.
AREAS OF EXPERTISE
 Petroleum Refining
 Petrochemicals
 Pipelines
 Oil and Gas (Offshore & Onshore)
 Storages and Terminals
 Fertilizers
 Infrastructures
 Mining & Metallurgy
 Water and Waste water management
 Power
MISSION
 Achieve ‘Customer Delight’ through innovative, cost effective and value
added consulting and EPC services.
 To maximize creation of wealth, value and satisfaction for stakeholders with
high standards of business ethics and aligned with national policies.

7. VISION
To be a world-class globally competitive EPC and total solutions Consultancy
Organisation.
MAJOR PROJECTS
EIL’s footprints are there in 20 out of 23 Refineries set up in India including 10
greenfield refineries and has also executed a large number of
revamp/modernization projects for
most of the Refining companies in
India. With an unmatched track
record of providing services to
major petrochemical complexes
helped in the establishment of 10
of the 11 mega petrochemical
complexes in India.
Its experience in implementing
pipelines projects for various high-
end products makes it a force to
reckon with an impressive record
of implementation of 47 Pipeline
Projects for transportation in
varied terrains. It has also involved
with some of the most challenging
offshore projects as well as proven capabilities in a wide array of onshore oil &
gas processing projects.
EIL is poised to play a pivotal role in the Strategic Crude Storage programme of
Govt. of India and has undertaken the construction of various kinds of tanks,
terminals and other storage facilities for oil and gas companies.
EIL has deployed cutting-edge technologies to execute Mining & Metallurgical
projects with an undertaking in various fields of infrastructure, Power, EPC
consultancy etc.
Project Category No. of Major
Projects
Petroleum Refining 15
Petrochemicals &
Chemicals
10
Pipelines 16
Oil & Gas (Onshore) 8
Oil and Gas (Offshore) 11
Strategic Storages 03
Mining & Metallurgy 12
Infrastructure 17
Waste Water
Management
04
Power 07
Fertilizers 06
EPC Contracting 12

8. SOME OF THE MAJOR MILESTONE PROJECTS-

9. 2. INTRODUCTION TO REFINING
WHAT IS REFINING?
Refining is an industrial process of purification of a substance or a form whereby crude oil
undergoes various chemical processes to convert it into products such as gasoline, diesel fuel,
asphalt base, heating oil, kerosene and liquefied petroleum gas. Refineries are very
complicated chemical processing plants that use reactions and separations to convert crude oil
into gasoline and other valuable products.
Major facility of a refinery includes the receipt and storage of crude oil, dispatch facilities
and storage of products, processing units, utilities generation facilities, effluent treatment
plants and flare systems etc.
Refining is carried out in three major steps-
 Separation
 Conversion
 Purification
WHY DO WE REFINE?
Crude oil is a natural occurring mixture of hydrocarbons formed from organic matter which is
a complex mixture of thousands of compounds of hydrocarbons, traces of other compounds
like sulphur, nitrogen, oxygen and other metals. Crude oil cannot be used as it occurs in
nature, other than burning for fuel, which is wasteful. It must be refined to manufacture
finished products such as gasoline and heating oil. It can be classified on the basis of
light/medium/heavy crudes, on the basis of sulphur content, paraffinic/naphthenic/aromatic
crudes, waxy/non waxy crudes, lube bearing/ non lube bearing crudes etc.
CRUDE OIL CHARACTERISTICS
 API GRAVITY :
Crude density is commonly measured by API gravity. API gravity provides a relative
measure of crude oil density.

10. ͦAPI = (141.5 / SP. GR. @ 60 deg F) - 131.5
Light Crude: API>300
Medium Crude: API: 25-300
Heavy Crude: API: 20-250
 SULPHUR CONTENT : Sulfur content measures if a crude is sweet (low
sulfur) or sour (high sulfur)
Typically less than 0.5% sulfur content - Sweet
Typically greater than 1.5% sulfur content – Sour
 SALT CONTENT - expressed as NaCl present in lb/ 1000 barrel (ptb)
 NITROGEN CONTENT - High Nitrogen is undesirable, basic nitrogen
destroys active sites of catalyst.
 METAL CONTENT – Metals are typically Ni, V, Cu, Fe etc. Metal content that
may vary from 10 PPM to 1000 PPM.
PETROLEUM PRODUCTS
PETROL
Petrol (motor gasoline) is made of cyclic compounds known as naphtha’s. It is made in two
grades: Regular (91 octane) and Super or Premium (96 octane), both for spark ignition
engines. These are later blended with other additives by the respective petrol companies.
JET FUEL/DUAL PURPOSE KEROSENE
The bulk of the refinery produced kerosene is high quality aviation turbine fuel used by the
jet engines of the domestic and international airlines. Some kerosene is used for heating and
cooking.
DIESEL OIL
This is less volatile than gasoline and is used mainly in compression ignition engines, in road
vehicles, agricultural tractors, locomotives, small boats and stationary engines. Some diesel
oil (also known as gas oil) is used for domestic heating.

11. FUEL OIL
A number of grades of fuel are produced from blending. Lighter grades are used for the
larger, lower speed compression engines (marine types) and heavier grades are for boilers and
as power station fuels.
BITUMEN
This is best known as a covering on roads and airfield runways, but is also used in industry a
waterproofing materials.
SULPHUR
Sulphur is removed from the crude during processing and used in liquid form in the
manufacture of fertilizers.

12. 3. OVERVIEW OF REFINING OPERATIONS
BLOCK FLOW DIAGRAM

13. DESALTER
Desalting process is used for the removal of salts like chlorides of calcium, magnesium, and
other impurities as these are corrosive in nature and predominantly chloride salts can
combine with water to form hydrochloric acid in atmospheric distillation unit overhead
systems causing significant equipment damage and processing upsets. There are two types of
desalting- single and multistage desalting. Salt content in commercial crude is moreover
around 10-200pb, earlier 10-20 ppb were considered satisfactorily low, but now a days
refiners aims at 5 ppb or less which is not possible through single stage desalting, hence
multistage desalting unit is required.
Desalting process basically consists of three main stages- Heating, Mixing and Settling.
Crude oil must be removed from crude oil prior to processing. Crude oil is pumped from
storage tanks and preheated by exchanging heat with atmospheric distillation product streams
to approximately 120℃. Inorganic salts are removed by emulsifying crude oil with water and
separating them in a desalter. Salts are dissolved in water and brine is removed using an
electrostatic field and sent to the waste water treatment unit.
CDU
The crude oil distillation unit (CDU) or Atmospheric distillation Unit is the first processing
unit in all petroleum refineries. The CDU distills the incoming crude oil into various fractions
for further processing based on their different boiling point ranges. Various steps in CDU are
– Preheating of desalted crude, Preflashing, Distillation, and finally stabilization of Naphtha.

14. Desalted crude is preheated to a temperature of 450-550℉ (260-290℃) through heat exchange
with distillation products, internal recycle streams and tower bottoms liquid. Finally, the
crude oil is heated to approximately 680℉ (360℃) in a fired heater and fed to the atmospheric
distillation tower.
Distillation concentrates lower boiling point material in the top of the distillation tower and
higher boiling point material in the bottom. Heat is added to the bottom of the tower using a
reboiler that vaporizes part of the tower bottom liquid and returns it to the tower. Heat is
removed from the top of the tower through an overhead condenser. A portion of the
condensed liquid is returned to the tower as reflux. The continuous vaporization and
condensation of material on each tray of the fractionating tower is what creates the separation
of petroleum products within the tower.
The most common products of CDU are fuel gas (butane & lighter gas), Naphtha, kerosene
(including jet fuel), diesel fuel, gas oil and residue. They runs at a pressure slightly above
atmospheric pressure in the overhead accumulator and the temperature above approximately
750℉(400℃) are avoided to prevent thermal cracking of crude oil into gases and coke.
VDU
The atmospheric bottoms also called reduced crude oil, from the atmospheric column is
fractionated in the Vacuum Distillation tower. Products that exist as a liquid at atmospheric

15. pressure will boil at lower temperature when pressure is significantly reduced. Absolute
operating pressure in a Vacuum tower can be reduced to 20mm of Hg or less (atmospheric
pressure is 760mm of Hg). In addition, superheated steam is injected with the feed and in the
tower bottom to reduce hydrocarbon partial pressure to 10mm of Hg or less.
Atmospheric Residue is heated to 750℉ (400℃) in a fired heater and fed to the vacuum
distillation tower where it is fractionated into light gas oil, heavy gas oil and vacuum residue.
HYDROTREATER
Hydrotreating is a catalytic process to stabilize products and remove objectionable elements
like sulfur, nitrogen and aromatics by reacting them with hydrogen. Cobalt Molybdenum
catalysts are used for desulfurization. When nitrogen removel is required in addition to sulfur,
nickel-molybdenum catalysts are used. In some instances, aromatics saturation is pursued
during the hydrotreating process in order to improve diesel fuel performance.
Most hydrotreating reactions take place between 600-800℉ (315-425℃) and at moderately
high pressure 500-1500psi (35-100 bar). As coke deposits an the catalyst, reactor temperature
must be raised. Once the reactor temperature reaches about 750℉ (400℃) the unit is
scheduled for shutdown and catalyst replacement.

16. Hydrogen is combined with the feed before or after it has been heated to reaction
temperature. The Combined feed enters the top of a fixed bed reactor, or series of reactors
depending on the level of contaminant removal required, where it flows downward over a bed
of metal oxide catalyst.
Hydrogen reacts with oil to produce hydrogen sulphide from sulphur, ammonia from
nitrogen, saturated hydrocarbons and free metals. Metals remain on the catalyst and other
products leave with the oil-hydrogen steam. Hydrogen is separated in a product separator.
Hydrogen sulfide and light ends are stripped from the desulfurized product. Hydrogen sulfide
is sent to sour gas processing and water removed from the process is sent to sour water
stripping prior to use as discharge.
VGO HYDROTREATING UNIT
In the VGO Hydrocracking Unit, heavy petroleum-based hydrocarbon feedstock (VGO) is
cracked into products of lower molecular weight such as liquified petroleum gas (LPG),
gasoline, jet fuel and diesel oil. The hydrocracking VGO process produces diesel oil with a
high cetane number but with low aromatics and sulphur content, making it ideal diesel
blending stock.

17. FCCU
The FCC is considered by many as the heart of modern petroleum refinery. FCC is the tool
refiners use to correct the imbalance between the market demand for lighter petroleum
products and crude oil distillation that produces an excess of heavy, high boiling range
products. The FCC unit converts heavy gas oil into gasoline and diesel.
The FCC process cracks the heavy gas oils by breaking the carbon bonds in large molecules
into multiple smaller molecules that boil in a much lower temperature range. The FCC can
achieve conversion of 70-90% of heavy gas oil into products boiling in the heavy gasoline
range. The reduction in density across the FCC also has the benefit of producing a volume
gain which as a result has a significant effect on refinery profitability.
FCC reactions are promoted at high temperatures from 950-1020℉ (510-550℃) but relatively
low pressures of 10-30psi (1-2bar). At these temperatures, coke formation deactivates the
catalyst by blocking reaction sites on the solid catalyst. The FCC unit utilizes a very fine
powdery catalyst known as a zeolite catalyst that is able to flow like a fluid in a fluidized bed.
Catalyst is continually circulated from the reactor to a regenerator where coke is burned off in
controlled combustion with air creating CO, CO2 , SOx , NOx as well as some other
combustion products.
Feedstock gas oil is preheated and mixed with hot catalyst coming from the regenerator at
approx 1400℉. The hot catalyst vaporizes the feedstock and heats it to the reaction

18. temperature. To avoid overcracking, which reduces yield at the expense of gasoline, reaction
time is minimized. The primary reaction occurs in the transfer line going to the reactor. The
primary purpose of the reactor is to separate catalyst from reaction products.
COKER (VISBREAKER)
Coking and Visbreaking are both thermal decomposition processes. With the exception of the
coking process, formation of coke in a petroleum refinery is undesirable because coke fouls
equipment and reduces catalyst activity. However, in the coking process, coke is intentionally
produced as a byproduct of vacuum residue conversion from low value fuel and asphalt into
higher value products.
The most common form of coking process is Delayed Coking where vacuum residue is
thermally cracked into smaller molecules that boil at lower temperatures. Products include
naphtha, gas oils and coke. Coke is sold as a fuel or specialty product into steel and
aluminium industry after calcining to remove impurities.
Vacuum residue is fed to the coker fractionators to remove as much as light material as
possible. Bottoms from the fractionators are heated in a direct fired furnace to more than
900F (480C) and discharged into a coke drum where thermal cracking is completed. High
velocity and steam injection are used to minimize the coke formation in furnace tubes. Coke
deposits in the drum and cracked products are sent to fractionator for recovery. Coke drum
typically operate in the 25-50psi (2-4bar) range while the fractionators operates at a pressure
slightly above atmospheric in the overhead accumulator. Fractionator bottoms are recycled
through the furnace to extinction. Coker light ends are highly unsaturated and are recovered
as an olefin feed source for alkylation.

19. Visbreaking is the milder form of thermal cracking often used to reduce the viscosity and
pour point of vacuum residue in order to meet specification for heavy fuel oil. Visbreaking
helps avid the use of expensive cutter stock required for dilution. The process is carefully
controlled to predominantly crack long paraffin chains off aromatic compounds while
avoiding coking reactions.
HYDROCRACKER
The Hydrocracker is more or less similar to the FCC but here cracking reactions take place in
an extremely hydrogen rich atmosphere. Hydrocracker units may be configured in single
stage or two stage reactor (primarily hydrotreating in the first stage and hydrocracking in the
second stage) systems that enable a higher conversion of gas oil into lower boiling products.
Hydrocracker run at high temperature of about 600-800F and at very high pressures of 1500-
3000psi (105-210 bar). Hydrocracker reactors contain multiple fixed beds of catalyst
typically containing palladium, platinum, or nickel.
Typical feedstock to a hydrocracker includes FCC crude oil, coker gas oil and gas oil from
crude distillation. Heavy Naphtha from the hydrocracker makes excellent Catalytic reformer
feedstock. Distillates from Hydrocracking make excellent jet fuel blend stocks. Light ends are
highly saturated and a good source of iso-butane for alkylation. The yield across a

20. Hydrocracker may exhibit volumetric gains as high as 20-25% making it a substantial
contributor to refinery profitability.
CATALYTIC REFORMING
Catalytic Reforming is the workhouse for octane upgradation in today’s modern refinery.
Molecules are reformed into structures that increase the percentage of high octane
components while reducing the percentage of low octane components. It converts straight
chain and saturated molecules into unsaturated cyclic and aromatic compounds. In doing so,
it liberates a significant amount of hydrogen that may be used in desulfurization and
saturation reactions elsewhere in the refinery.
Reforming uses platinum catalyst. Sulphur poisons the catalyst; therefore, virtually all
sulphur must be removed prior to reforming. Temperature is used to control produced octane.
The unit is operated at temperatures between 925-975℉ (500-525℃) and pressure between
100-300psi (7-25bar). As a result of very high reactor temperatures, coke forms on the
catalyst, which reduces the activity. Coke must be either removed continuously (Continuous
Catalyst Regeneration CCR units) or periodically to maintain performance.
ISOMERIZATION
Isomerization can result in significant octane increase by converting normal paraffins into
their isomers in the isomerization unit.

21. Isomerization catalysts contain platinum and, like reforming they must have all sulfur
removed. Additionally, some catalyst requires continuous addition of small amount of
organic chlorides to maintain activity. Organic chlorides are converted to hydrochloric acid;
therefore, isomerization feed must be free of water to avoid serious corrosion problems.
Desulfurized feed and hydrogen are dried in fixed beds of solid desiccant prior to mixing
together. The mixed feed is then heated and passes through a hydrogenation reactor to
saturate olefins to paraffin’s and saturate benzene. Then the hydrogenation effluent is cooled
and passed through a isomerization reactor from where the final effluent is cooled and
separated as hydrogen and LPGs which typically go to fuel gas, and isomerate product for
gasoline blending Isomerization uses reaction temperatures of 300-400℉ (150-200℃) at
pressures of 250-400psi (17-27bar).
ALKYLATION
Alkylation is a refining process that provides an economic outlet for very light olefins
produced at the FCC and Coker. The process takes small molecules and combines them into
larger molecules with high octane and low vapor pressure characteristics.
In the Alkylation Unit, propylene, butylenes and sometimes pentylenes (also known as
amylenes) are combined with iso-butane in the presence of a strong acid catalyst (either
hydrofluoric acid or sulfuric acid) to form branched, saturated molecules. Alkylate has low
vapor pressure making it a valuable gasoline blending component particularly for premium
grade products. It contains no olefins, aromatics or sulfur.

22. Sulfuric Acid Alkylation runs at 35-60˚F (2-15˚C) to minimize polymerization reactions
while HF Alkylation, which is less sensitive to polymerization reactions, runs at 70-100˚F
(20-38˚C). Chilling or refrigeration is required to remove heat of reaction.
Alkylation products are distilled to remove propane, iso-butane and alkylate. Sulfuric acid
sludge must be removed and regenerated. HF is neutralized with KOH, which may be
regenerated and returned to the process.
SULPHUR RECOVERY UNIT
The sulphur recovery process used in most refineries is a “Claus Unit” which converts H2S
gas into elemental sulphur. In general, the Claus unit involves combusting one-third of the
hydrogen sulphide (H2S) into SO2 and then reacting the SO2 with the remaining H2S in the
presence of cobalt molybdenum catalyst to form elemental sulphur.
Generally, multiple conversion reactors are required. Conversion of 96-97% of the H2S to
elemental sulphur is achievable in a Claus unit. If required for air quality, a tail gas treater
may be used to remove remaining H2S in the tail gas from the sulphur recovery process.

23. AMINE RECOVERY UNIT
The amine treating unit removes CO2 and H2S from sour gas and hydrocarbon streams in the
amine absorber. The amine is regenerated in the amine regenerator and recycled to the amine
absorber.
The sour gas streams enter the bottom of the Amine Absorber. The cooled lean amine is trim
cooled and enters the top of the contactor column. The sour gas flows upward counter-current
to the lean amine solution. An acid-gas-rich-amine solution leaves the bottom of the column
at an elevated temperature, due to the exothermic absorption reaction. The sweet gas, after
absorption of H2S by the amine solution, flows overhead from the Amine Absorber.
The Rich Amine Surge Drum allows separation of hydrocarbon from the amine solution.
Condensed hydrocarbons flow over a weir and are pumped to the drain. The rich amine from
the surge drum is pumped to the Lean/Rich Amine Exchanger.
The stripping of H2S and CO2 in the Amine Regenerator regenerates the rich amine solution.
The Amine Regenerator or Reboiler supplies the necessary heat to strip H2S and CO2 from
the rich amine, using steam as the heating medium.
Acid gas, primarily H2S and water-vapour from the regenerator is cooled in the Amine
Regenerator Overhead Condenser. The mixture of gas and condensed liquid is collected in
the Amine Regenerator Overhead Accumulator. The uncondensed gas is sent to Sulfur
Recovery.
The Amine Regenerator Reflux Pump, pumps the condensate in the Regenerator
Accumulator, mainly water, to the top tray of the Amine Regenerator. A portion of the pump
discharge is sent to the sour water tank.

24. Lean amine solution from the Amine Regenerator is cooled in the Lean/Rich Exchanger. A
slipstream of rich amine solution passes through a filter to remove particulates and
hydrocarbons, and is returned to the suction of the pump. The lean amine is further cooled in
the Lean Amine Air Cooler, before entering the Amine Absorber.
SOUR WATER STRIPPING
Stripping stream and wash water in various refining operations is condensed and removed
from overhead condensate accumulators or product separators. These water contains
impurities most notably sulphur compounds and ammonia. Hydrogen sulfide and ammonia
are removed in the sour water stripper.
The sour water is received from the refinery in the flash drum, where light hydrocarbons are
flashed off. The sour water is then fed to the feed prep tank, where the feed is mixed and
stabilized. Liquid hydrocarbons entrained in the sour water are removed in the feed prep tank.
The sour water is then heated in the feed/bottoms exchanger and fed to the stripper column.
Steam, generated in the reboiler, heats the water and strips the hydrogen sulfide (H2S) and
ammonia (NH3) from the water. The stripped water from the column is cooled in the
feed/bottoms exchanger and in the stripped water cooler, and returned to the refinery. The
H2S and NH3 removed from the sour water is cooled in the pump-around cooler system or in
an overhead condenser system and sent to the sulfur recovery unit for further processing.

25. HYDROGEN MANUFACURING UNIT
In the hydrogen manufacturing unit, hydrogen is produced by converting hydrocarbons and
steam into hydrogen, and produces CO and CO2 as byproducts. The hydrocarbons (preferably
light hydrocarbons and butane) are desulfurised and then undergo the steam reforming
reaction over a nickel catalyst. The second reaction is commonly known as the water gas shift
reaction.
The process of reforming can be split into three phases of preheating, reaction and
superheating. The overall reaction is strongly endothermic and the design of the HMU
reformer is a careful optimization between catalyst volume, furnace heat transfer surface and
pressure drop.
In the preheating zone the steam/gas mixture is heated to the reaction temperature. It is at the
end of this zone that the highest temperatures are encountered. The reforming reaction then
starts at a temperature of about 700°C and, being endothermic, cools the process. The final
phase of the process, superheating and equilibrium adjustment, takes place in the region
where the tube wall temperature rises again.
MEROX TREATMENT
Merox treatment is a process to sweeten products by extracting or converting mercaptan
sulfur to less objectionable disulfides. It is often used to treat products such as liquidified
petroleum gases, naphtha, gasoline, kerosene, jet fuel and heating oil’s.
Feed free from H2S is contacted with caustic in a counter-current extraction column. Sweet
product exits the column overhead and caustic/extracted mercaptans exit the column bottom
as extract. Air and possibly catalyst are mixed with extract and sent to an oxidation reactor
where caustic is regenerated and mercaptans are converted to disulfides. Disulfides are
insoluble in water and can be removed in a product separator that vents excess air and gas for
disposal or destruction and separates sulfide oil, which may be returned to the refining
process, from regenerated caustic, which is returned to the extraction column. Over time
caustic will become spent and must be wasted to other refinery uses or to spent caustic
destruction.

26. When removal of mercaptan sulfur is not required, "sweetening" may be applied to improve
odor where mercaptan sulfur is converted to disulfide and carried out with the petroleum
product. For sweetening, dilute caustic is added to the product prior to air injection.
Combined feed enters a fixed bed reactor where a catalyst oxidizes mercaptan sulfur into
disulfides. Caustic is removed from the bottom of the reactor and wasted to the sewer or
spent caustic treatment.
BITUMEN BLOWING
Bitumen is obtained by vacuum distillation or vacuum flashing of an atmospheric residue.
This is ‘Straight run’ bitumen. An alternative method of bitumen production is by
precipitation from residual fractions by propane or butane-solvent deasphalting. The grade of
the bitumen depends on the amount of volatile material that remains in the product: the
smaller the amount of volatiles, the harder the residual bitumen.
The grade of bitumen production which does not meet the market product quality
requirements by straight run vacuum distillation are manufactured by blowing air through the
hot liquid bitumen in a Bitumen Blowing Unit.
By blowing, the asphaltenes are partially dehydrogenated (oxidised) and form larger chains
of asphaltenic molecules via polymerisation and condensation mechanism. Blowing will
yield a harder and more brittle bitumen (lower penetration, higher softening point), not by
stripping off lighter components but changing the asphaltenes phase of the bitumen. The
bitumen blowing process is not always successful: a too soft feedstock cannot be blown to an
on-specification harder grade.
The blowing process is carried out continuously in a blowing column in which the liquid
level is kept constant by means of an internal draw-off pipe. This makes it possible to set the
air-to-feed ratio (and thus the product quality) by controlling both air supply and feed supply
rate. The feed to the blowing unit (at approximately 210 0C), enters the column just below
the liquid level and flows downward in the column and then upward through the draw-off
pipe. Air is blown through the molten mass (280-300 0C) via an air distributor in the bottom
of the column. The bitumen and air flow are countercurrent, so that air low in oxygen meets
the fresh feed first. This, together with the mixing effect of the air bubbles jetting through the
molten mass, will minimize the temperature effects of the exothermic oxidation reactions:
local overheating and cracking of bituminous material. The blown bitumen is withdrawn

27. continuously from the surge vessel under level control and pumped to storage through
feed/product heat exchangers.
NEEDLE COKE UNIT
Needle Coke is a premium grade, high value petroleum coke used in the manufacturing of
graphite electrodes for the arc furnaces in the metallurgy industry. Its hardness is due to the
dense mass formed with a structure of carbon threads or needles oriented in a single direction.
Needle coke is highly crystalline and can provide the properties needed for manufacturing
graphite electrode. It can withstand temperatures as high as 28000℃.
Formation of needle coke requires specific feedstock’s, special coking and also special
calcination conditions. If feedstocks are suitable for needle coke, process conditions for
coking and calcination are selected to improve the properties and yield of the needle coke.
Typical yield of needle coke is 18-30 wt% of fresh feed. The maximum limits of sulfur and
ash in calcined needle coke are 0.6 and 0.3 wt% respectively.
Refineries having delayed coker unit, a residue hydrotreater unit or a RFCC/ FCC unit for
processing low sulfur feed are suitable for considered in this technology.

28. BIBLIOGRAPHY
The following are the sources used while making the project report -
1. EIL - Guideline for Refinery Process