1. A
REPORT ON VOCATIONAL TRAINING
IN
OIL AND NATURAL GAS CORPORATION LIMITED
HAZIRA, SURAT
Training Period: 18/12/2015 to 18/01/2016
SUBMITTED BY, MENTOR,
ARPAN SAXENA DHARMENDRA KUMAR
From,
C. K. Pithawala College of Engineering and Technology
Surat.

2. ACKNOWLEDGEMENT
I owe my credits of this summer training to:-
Miss Sandhya Bhatt GSU/GDU
Sh. Gaurav Pandey – LPG & KRU
Sh. Ravi Kant – CFU
Sh. Dharmendra Kumar– Utility and offsite
Sh. H. M. Ray – Cogeneration plant
Sh. Abhilash Patel – DPD/CWU
Sh. R. S. Pradhan – SRU

3. INDEX
PREFACE
Teaching gives the knowledge of theoretical aspects of management
but implementation of theory gives practical knowledge of management field.
Practical Knowledge of theory is of greater important for an engineering student. I
SL.NO TITLE PAGE NO.
2. Gas Terminal & Slug Catcher 8
3. Gas Sweetening Unit 8
4. Gas Dehydration Unit 12
5. Dew Point Depression Unit 13
6. Condensate Fractionation Unit 19
7. Sulphur Recovery Unit 15
8. Liquefied Petroleum Gas Unit (LPG) 24
9. Kerosene Recovery Unit 23
11. Utility System 27
12 CO-GEN 39
13 MECHANICAL MENTINANCE 47
14 MECHANICAL COMPONENTS IN PLANT 52

4. am thankful to my college, CKPCET, Surat for arranging summer training
before entering into the specialization field of master. This project report is
an outline of what we have learnt during our training period at Oil & Natural Gas
Corporation Limited (ONGC), one of the prestigious public sector
companies running with strategy values and time management. We are
thankful to Oil & Natural Gas Corporation Limited for giving us
such a valuable opportunity to work with them.
I am thankful to Oil & Natural Gas Corporation Limited
for giving me such a valuable opportunity to work with them.
ONGC as Processing Industry:
Oil and Natural Gas Corporation is a public sector petroleum company
involved in wide scale exploitation of oil as well as natural gas from the Indian
mainland as well as from Arabian Sea and Indian Ocean. ONGC is one among the
Indian Government’s Navrathna Companies which involves the most profit
making nine public sector companies and hence is one of the most profit making
companies in India.
Foundation:
In August 1956, the Oil and Natural Gas commission was formed.
Raised from mere directorate status to commission, it had enhanced powers. In
1959, these powers were further enhanced by converting the commission into a
statutory body by an act of Indian Parliament Oil and Natural Gas Corporation
Limited (ONGC) (incorporated on June 23, 1993) is an Indian Public Sector
Petroleum Company. It is a fortune global 500 companies ranked 335th, and
contributes 51% of India’s crude oil production and 67% of India’s natural gas
production in India. It was set up as a commission on August 14, 1956. Indian
government holds 74.14 % equity stake in this company. ONGC is one of Asia’s
largest and most active companies involved in exploration and production of oil .It
is involved in exploring for and exploiting hydrocarbons in 26 sedimentary basins
of India. It produces 30% of India’s crude oil requirement. It owns and operates

5. more than 11,000 kilometers of pipelines in India. In 2010, it was ranked 18th in
the Plants Top 250 Global Energy Company Rankings and is ranked 413st in the
2012 Fortune Global 500 list. It is the largest company in terms of market cap in India.
ONGC Represents India’s Energy Security
ONGC has single-handedly scripted India’s hydrocarbon saga by:
• Establishing 7.38 billion tons of In-place hydrocarbon reserves with more
than 300discoveries of oil and gas; in fact, 6 out of the 7 producing basins
have been discovered by ONGC: out of these In-place hydrocarbons in
domestic acreages, Ultimate Reserves are 2.60 Billion Metric tons (BMT) of
Oil plus Oil Equivalent Gas (O+OEG).
• Cumulatively produced 851 Million Metric Tonnes (MMT) of crude and 532
Billion Cubic Meters (BCM) of Natural Gas, from 111 fields.
• ONGC has bagged 121 of the 235 Blocks (more than 50%) awarded in the 8
rounds of bidding, under the New Exploration Licensing Policy (NELP) of the
Indian Government.
• ONGC’s wholly -owned subsidiary ONGC Videsh Ltd. (OVL) is the biggest
Indian multinational, with 33 Oil & Gas projects (9 of them producing) in 15
countries, i.e. Vietnam, Sudan, South Sudan, Russia, Iraq, Iran, Myanmar,
Libya, Cuba, Colombia ,Nigeria, Brazil, Syria, Venezuela and Kazakhstan.
HAZIRA PLANT

7. INTRODUCATION TO HAZIRA GAS PROCESSING COMPLEX
Natural gas has gained increased importance in the recent past by virtue of
its usage as substitute for coal, petrol and diesel as fuel in industrial boilers and
furnaces. Natural gas being rich in propane and butane gives straight run LPG. It
has now become possible to liquefy and transport natural gas. It is available for
uses fuel in automobiles also.
Some of the gas fields in India are producing Sour Natural gas containing
poisonous Hydrogen Sulphide Gas in varying amount. Sour natural gas containing
H2S require special treatment for removal of the poisonous gas. HC Condensate
associated with Sour Natural Gas also becomes sour and gives rise to production
of sour LPG which requires additional treatment for making it sweet, marketable
and safe for use.
Hazira Gas Processing Complex is receiving sour natural gas from South
Bassein Gas Fields which is a sub sea reservoir. The gas is transported from South
Basin field to HGPC through a sub sea pipeline. The gas is received at Gas
Terminal in a Slug Catcher where gas and slug containing HC Condensate,
moisture and chemicals (like corrosion inhibitors) are separated. Gas and
associated Condensate are sent further in separate system for processing.
The sour gas processing system at Hazira Plant, consist of followings:
1. Gas Receipt Terminal
2. Gas Sweetening Unit
3. Gas Dehydration Unit
4. Dew Point Depression Unit
5. Sulphur Recovery Unit
6. Sour Condensate Processing Unit

8. 7. Gas Based LPG Recovery Unit
8. Kerosene Recovery Unit
GAS RECEIPT TERMINAL
At the Gas Terminal after the first receiving valves the sour gas and
condensate are then routed through a set of Pressure Reduction Control System.
These control valves maintain down stream pressures at a pre set value.
(Normally set at 70 kg / cm2). In case the pressure exceeds the value, these valves
try to close and maintain the pressure. These control valves are operated
normally in automatic mode. The Gas and Condensate then passes through
cyclone separators / filters and further distributed to Slug Catchers.
Slug, catchers are having liquid holding of 11,000 cubic meters each. They
are nothing but set of parallel pipe fingers of 48 inch diameter and approximately
500 meters in length. These pipe fingers are mounted at a slope of 1:500; thus
forming separation and collection zone. The sour gas separated is taken out from
top riser pipes to Gas Sweetening Units and the sour liquid thus collected is
routed to Condensate Fractionation Units.
GAS SWEETENING UNIT
Sour Gas from slug Catcher is distributed to different GSU trains under the
pressure control and flow control. Sour gas is first preheated up to 40 – 45 Deg. C.
sour Condensate of gas from CFU also enters down stream of preheated under

9. flow control. The combine Sour gas passes through knock out drums and enters
the bottom of high pressure absorber column.
The Absorber is having valve type trays. The amine solution (Methyl Di
ethanol Amine of concentration 480 gm/liter) is pumped from individual trains
units tank and is injected at the desired tray of the column. The amine and gas
flow in the column is counter current. The sweet gas from the top of the column
is cooled and routed to GDU / LPG units through a knock out drum (K.O.D).

10. 45
ABSORBER
AMINE
TANK
PUMP
SOUR GAS
FROM CFU
SOUR GAS
FROM S/C
RICH
AMINE
SWEET
GAS
60kg/cm2
35 C
H.P. ABSORPTION
The rich amine from the bottom of the column flows to medium pressure
absorber / flash drum. The flash gases go to fuel gas header. The amine then
passes to the plate heat exchanger (exchanger returns hot lean amine solution)
and enters a regenerator column where it regenerates.

11. REGENERATOR
RICHAMINE
REBOILER
COOLER
REFLUX
ACID
GAS
LEAN AMINE
1 kg/cm2
128 C
AMINE REGENERATION
LP STEAM
REGENERATOR
RICHAMINE
REBOILER
COOLER
REFLUX
ACID
GAS
LEAN AMINE
1 kg/cm2
128 C
AMINE REGENERATION
LP STEAM
Regenerated column is also having valve type trays with associated reflux
and reboiler arrangement. Regenerated lean amine from the bottom goes back to
the MDEA tank and is recycled in the process.
Liberated acid gas from top of the regenerator column goes to Sulphur
Recovery unit under pressure control. The acid gas mainly consists of Carbon
dioxide, Hydrogen Sulphide and some water.

12. GAS DEHYDRATION UNIT:
Purpose of GDU:
• To remove water vapors from sweet gas with the help of tri-ethylene glycol
solution.
Design of GDU:
• The purpose of a glycol dehydration unit is to remove water from natural
gas and natural gas liquids.
• When produced from a reservoir, natural gas usually contains a large
amount of water and is typically completely saturated or at the water dew
point. This water can cause several problems for downstream processes
and equipment
• At low temperatures the water can either freeze in piping or, as is more
commonly the case, form hydrates with CO2 and hydrocarbons (mainly
methane hydrates).

13. • Depending on composition, these hydrates can form at relatively high
temperatures plugging equipment and piping.
• Glycol dehydration units depress the hydrate formation point of the gas
through water removal.
• Without dehydration, a free water phase (liquid water) could also drop out
of the natural gas as it is either cooled or the pressure is lowered through
equipment and piping. This free water phase will often contain some
portions of acid gas (such as H2S and CO2) and can cause corrosion.
DEHYDRATION OF GLYCOL
Function of glycol dehydration unit is to remove moisture from
rich glycol and convert it into lean glycol.

14. DEW POINT DEPRESSION UNIT:
The purpose is to remove hydrocarbon condensate from the
sweetened and dehydrated gas by chilling to avoid hydrate formation in long
distance H-B-J pipeline. The feed gas from GDU train is chilled to about (-) 5 deg.C
in a chiller with the help of propane refrigerant in close circulation cycle. The
cooled gas condensate is pumped to LPG plant for distillation. This treated gas is
then sent to GAIL for onward transmission to H-B-J

15. 39
PROPANE REFRIGERATION CYCLE
2.7 kg/cm2
15 kg/cm2
COMPRESSOR
CONDENSER
ACCUMULATOR
SUPER
COOLER
CHILLER
0 oC 70oC
40oC
30oC
- 5oC
KOD
LIQ.
PROPANE
QUENCH
pipeline and partly to local consumers.

16. 38
GAS CHILLING
COND.
TO LPG
SEPARATOR
CHILLER
GAS/GAS
COOLER
SWEET &
DRY GAS
FROM GDU
GAS TO GAIL
/HBJ PIPELINE
LIQ. PROPANE FROM
ACCUMULATOR
PROPANE VAP. TO
COMPRESSOR
5oC
12oC
SULPHUR RECOVERY UNIT:
Acid gas from GSU regenerator is brought to Sulphur recovery Unit to
convert the poisonous Hydrogen Sulphide Gas into elemental Sulphur by liquefied
oxidation catalytic process. Acid gas coming from GSU is taken to Absorber /
Oxidizer vessel via inlet KOD under flow control which contains LOCAT solution.
Hydrogen Sulphide is oxidized to elemental Sulphur by atmospheric air in
presence of the catalyst. Carbon dioxide, Oxygen, Nitrogen, Water vapour and

17. traces of Hydrogen Sulphide (within the permissible limit set by Pollution Control
Board) is
19
ABSORBER / OXIDIZER
ADDITIVES
ARI 310 C
ARI 310 M
Surfactant
Biochem
Defoamer
SLURRY
PUMP
SULPHUR
SLURRY
TO MELTER
AIR
BLOWER
ACID
GAS
LOCAT
vented to the atmosphere, LOCAT solution returns back to Oxidizer /
Absorber under pressure control and Molten Sulphur thus separated is taken to a
surge drum under level control. Molten Sulphur from surge drum is pumped by
vertical pumps to preconditioning unit for temperature conditioning with the help
if thermal fluid and the sent to Roto former. Here the Molten Sulphur is palletized
and then bagged in HDPE Bags, in the unit for final disposal (Selling in the
Market). Sulphur Recovery Unit has been installed as an environmental protection
unit only.

18. 10
CW
KOH
ARI 600
ARI350
ARI310C
ARI400
LOCAT
RETURN
MELTER
SEPERATOR
SURGE
DRUM
MOLTEN
SULPHUR
ROTOFORMERBLOWERACID GAS
FROM GSU
ACID
GAS
KOD
SUMP
STACK AT 28 M HEIGHT
ABSORBER
OXIDISER
SLURRY
KOD
COOLER
BAGGING
SRU BLOCK DIAGRAM

19. 11
Acid Gas
Air
Sulphur Particles
Scraper
Reduced LoCAT
Regenerated LoCAT
Center Well ( 4 Nos. )
Air Spargers
Acid Gas Spargers
Air Blast Line
Auto circulation
Flow path
ABSORBER INTERNALS

20. 12
SEPARATOR
SURGE DRUM
MELTER
STEAM
MOLTEN
SULPHUR
ROTOFORMER
BAGGING
FROM
ABSORBER
LOCAT RETURN
MELTER / SEPARATOR
4 kg/cm2
140 oC
SOUR CONDENSATE PROCESSING UNIT
Sour Condensate Processing Unit is Hazira Project is called as Condensate
Fractionation Unit (CFU). Associated Sour gas condensate from Slug Catcher is
preheated and taken into a condensate surge drum operating at slightly lower
pressure than incoming pressure in CFU. Condensate, Water and Gas are
separated in the surge drum. Condensate from bottom of the drum is pumped to

21. a stripper column through coalesce filters under flow control. In stripper column,
H2S is stripped along with lighter Hydro carbons and taken out from the column.
Liberated gas from surge drum and stripper to are jointly compressed by Off Gas
compressor and feed to Gas Sweetening train for elimination of H2S .
The liquid from stripper bottom is reboiled and feed to LPG column under
level and flow control in LPG Column LPG is taken out from the top through
Condenser reflux drum and NGL from the bottom through NGL cooler, under level
control to storage area. It is being continuously monitored that LPG coming out
from distillation column should not contain H2S more than 20 PPM. LPG thus

22. 26
REFLUX
TOP
PRODUCT
BOTTOM
PRODUCT
FEED
REBOILER
COLD LIQUID
HOT VAPOR
VALVE TRAY
DISTILLATION COLUMN PRINCIPLE
RECTIFYING
SECTION
STRIPPING
SECTION
CONDENSER
prod
uced from CFU is a sour LPG and the same is sweetened through processing in
Caustic Wash Unit before sending to LPG spheres.

23. 28
STRIPER & OFF GAS COMPRESSOR
18 kg/cm2
OFF GAS
TO GSU
60 kg/cm2
TO LPG COLM.
MP STEAM
COMPRESSOR
60
valve trays
140oC
4 PPM H2S max.
FROM
FILTER /
COALCR.
In case it is found that the LPG is sphere contains more than 4 PPM of H2S
after sampling (as preparation for dispatch to consumers), the bulk of LPG is re-
routed through Caustic Wash Unit to restrict the H2S level below permissible limit.

24. 29
LPG COLUMN
10 kg/cm2
TOFLARE
LPG TO
SPHERE
NGL TO
KRU / TANK
HP
STEAM
FRM
STRIPPER
BOTTM.
REFLUX
DRUMREFLUX
190 oC
60 oC
60 valve
trays
KEROSENE RECORY UNIT
NGL produced from CFU is given value addition in KRU by way of producing
aromatic rich naphtha (ARN), superior kerosene oil (SKO), heavy cut (HC) and/or
high-speed diesel (HSD). The hot NGL is fed to Naphtha Column for distillation
from where Naphtha is recovered as a top product. The bottom stream is fed to
the Kerosene column through the gas fired furnace for further fractionation
.Kerosene/ ATF is recorded from top of the Kerosene Column and HSD/ Heavy Cut
is recovered from the bottom. A suitable chemical additive is added in ATF to

25. maintain electrical conductivity, and storage stabilizer for HSD before these
products are sent to storage.
LPG RECOVRY UNIT:
A part of sweet gas from outlet of GSU (about 5 MMSCMD) and all the sweet
condensate from DPD are taken as feed to LPG Recovery Unit. State-of-the-art
cryogenic process using Turbo-Expander has been used for the first time in ONGC.
The feed gas is first dried in molecular sieve dryers and then chilled in a Cold Box
to (-) 300
C. The chilled vapor is expanded isentropically in Turbo-Expander wherein
temperature of the gas falls to (-) 570
C. The heavier hydrocarbons (C 3+) get
liquefied in the chilling process, which are separated for fractionation in LEF and
LPG columns. The lean gas liberated from top of LEF column is further
compressed as per requirement of downstream consumers. The products coming
out from LPG column are LPG as a top product and Naphtha as a bottom product.
A part of LPG is further distilled to obtained propane, which is used as a
refrigerant in LPG and DPD unit.

26. LPG Spheres:-
The output from LPG stripper columns are generally LPG and other gases.This
LPG is stored in large LPG spheres.This LPG is forced to the hight of the LPG
spheres by pumps.
The design of the spheres are of spherical shape.There are 2 main
reasons for it.
1. The inlet fire water from the top can be easily expanded as it enters the
spheres. And is given for insulation process.
2. The stresses devloped on the sharp edges of other shapes like cubic shape,
cylindrical shape etc, are hiher according to LAME’S Theorm . Whereas in

27. spherical shape there are no sharp edges which reduces the stress
development.
The spheres are situated at several hights from ground because it causes
sufficient presure different due to difference in height.

28. UTILITY SYSTEM
Under Utility and Mechanical Maintenance Unit, there comes the following
1) IG plant
2) Cooling towers
3) Heat Exchangers
4) Fire water
5) Steam
IG PLANT
Utility department meets the basic requirements of the plants which are
necessary
For plant to run such utilities are
1.air
2.water
3.steam
1.Air -there are 3 types of air
a) plant air-plant air is compressed air used in cleaning purpose.
b) Instrument air- instrument air is compressed air without moisture
content. main use of instrument air is to actuate pneumatic valves.
c) inert gas- inert gas in plant is produced by removing oxygen content from
instrument air and it is used where there are chances of fire. During purging of
the LPG spheres N2 is used.

29. KSS/HZR-UTLT/2002 14
X 101
C101
H 101
CW
FG
SEAL POT
V 101
C102 A
C102 C
C102 B
X 102
V 102
E 102
V 104
X 103
V 105
AD-A
V 105
AD-B
V 106
X 105E 103
E 104
V 107
P 103 A/B
IG PLANT - PFD
AIR BLOWER
COMBUSTION
CHAMBER
SUMP
KOD
FILTER
PROTECTOR
COMPRESSORS
AFTER
COOLER MOISTURE
SEPARATOR
PRE
FILTER
DRYERS
FILTERHEATER
AFTER
COOLER
MOISTURE
SEPARATOR
IG RECEIVER
FROM TR. B
TO TR. B

30. KSS/HZR-UTLT/2002 10
PRE FILTER HEATER
FIC
TOWER I TOWER II
x
x
x
4 WAY
VALVE
COOLER
MOISTURE
SEPARATOR
AFTER FILTER
IA TO
HEADER
FROM
COMP.
190
o
C
185
o
C
35
o
C
BANK I 190
o
C
BANK II 220
o
C
BANK III 220
o
C
AIR DRYERS

31. KSS/HZR-UTLT/2002 16
COMP RESSORS
AIRRE CEIVE R
PRE FILT ER
ADSORBE RS
O2
BLOW SILEN CE R
F 001
V 104 A V 104 B V 102
N2
VESSEL
PRODUCT GAS
FILTERS
V 43 - 1
F 002 /F 003
V 43 - 2
N2
BLOW SILEN CER
FI 101
PRODUCT
FLOW ME TE R
V 103
PRODUCT N2
STORAGE
N2 PLANT PFD
K 101A
K 101B
V 101
25K001

32. HEAT EXCHANGER
KSS/HZR-UTLT/2002 26
HEAT EXCHANGERS
CWS
CWRPROCESS FLUID IN
PROCESS FLUID OUT
DRAIN
VENT
FLARE
DOME
TUBES
A heat exchanger is a device used to transfer heat between one or more fluids. The fluids may
be separated by a solid wall to prevent mixing or they may be in direct contact
Inside ongc hazira only two types of heat exchangers are used
1.shell and tube type-
Shell and tube heat exchangers consist of series of tubes. One set of these tubes
contains the fluid that must be either heated or cooled. The second fluid runs
over the tubes that are being heated or cooled so that it can either provide the
heat or absorb the heat required. A set of tubes is called the tube bundle and can
be made up of several types of tubes: plain, longitudinally finned, etc. Shell and
tube heat exchangers are typically used for high-pressure applications (with

33. pressures greater than 30 bar and temperatures greater than 260 °C).This is
because the shell and tube heat exchangers are robust due to their shape.
Several thermal design features must be considered when designing the tubes in
the shell and tube heat exchangers: There can be many variations on the shell and
tube design. Typically, the ends of each tube are connected to plenums
(sometimes called water boxes) through holes in tubesheets. The tubes may be
straight or bent in the shape of a U, called U-tubes.
2.plate heat exchanger
A plate heat exchanger is a type of heat exchanger that uses metal plates to
transfer heat between two fluids. This has a major advantage over a conventional
heat exchanger in that the fluids are exposed to a much larger surface area
because the fluids spread out over the plates. This facilitates the transfer of heat,
and greatly increases the speed of the temperature change. Plate heat
exchangers are now common and very small brazed versions are used in the hot-
water sections of millions of combination boilers. The high heat transfer efficiency
for such a small physical size has increased the domestic hot water (DHW)
flowrate of combination boilers. The small plate heat exchanger has made a great
impact in domestic heating and hot-water. Larger commercial versions use
gaskets between the plates, whereas smaller versions tend to be brazed.
The concept behind a heat exchanger is the use of pipes or other containment
vessels to heat or cool one fluid by transferring heat between it and another fluid.
In most cases, the exchanger consists of a coiled pipe containing one fluid that
passes through a chamber containing another fluid. The walls of the pipe are
usually made of metal, or another substance with a high thermal conductivity, to
facilitate the interchange, whereas the outer casing of the larger chamber is made
of a plastic or coated with thermal insulation, to discourage heat from escaping
from the exchanger.

34. COOLING TOWER
Cooling Tower is the utility which is used to cool the hot water received from
various parts of plant with heat transfer from atmosphere.
There are 2 types of cooling tower
1.cross flow cooling tower
Crossflow is a design in which the air flow is directed perpendicular to the water
flow (see diagram at left). Air flow enters one or more vertical faces of the cooling
tower to meet the fill material. Water flows (perpendicular to the air) through the
fill by gravity. The air continues through the fill and thus past the water flow into
an open plenum volume. Lastly, a fan forces the air out into the atmosphere.
A distribution or hot water basin consisting of a deep pan with holes or nozzles in
its bottom is located near the top of a crossflow tower. Gravity distributes the
water through the nozzles uniformly across the fill material.
Advantages of the crossflow design:

35. • Gravity water distribution allows smaller pumps and maintenance while in
use.
• Non-pressurized spray simplifies variable flow.
• Typically lower initial and long-term cost, mostly due to pump
requirements.
Disadvantages of the crossflow design:
• More prone to freezing than counter flow designs.
• Variable flow is useless in some conditions.
• More prone to dirt buildup in the fill than counter flow designs, especially
in dusty or sandy areas.
2.counter flow cooling tower
In a counter flow design, the air flow is directly opposite to the water flow (see
diagram at left). Air flow first enters an open area beneath the fill media, and is
then drawn up vertically. The water is sprayed through pressurized nozzles near
the top of the tower, and then flows downward through the fill, opposite to the
air flow.
Advantages of the counter flow design:
• Spray water distribution makes the tower more freeze-resistant.
• Breakup of water in spray makes heat transfer more efficient.
Disadvantages of the counter flow design:
• Typically higher initial and long-term cost, primarily due to pump
requirements.
• Difficult to use variable water flow, as spray characteristics may be
negatively affected.
• Typically noisier, due to the greater water fall height from the bottom of
the fill into the cold water basin

36. Parameters of cooling tower-
Range-The range is the temperature difference between the warm water inlet
and cooled water exit.
Approach — The approach is the difference in temperature between the cooled-
water temperature and the entering-air wet bulb temperature (twb). Since the
cooling towers are based on the principles of evaporative cooling, the maximum
cooling tower efficiency depends on the wet bulb temperature of the air. The
wet-bulb temperature is a type of temperature measurement that reflects the
physical properties of a system with a mixture of a gas and a vapor, usually air and
water vapor
Approach=temp. of cooling water- temp. of saturated air
Approach is generally between 2-3 `C
Cooling Efficiency –
he cooling tower efficiency can be expressed as
μ = (ti - to) 100 / (ti - twb) (1)
where
μ = cooling tower efficiency (%) - common range between 70 - 75%
ti = inlet temperature of water to the tower (o
C, o
F)
to = outlet temperature of water from the tower (o
C, o
F)
twb = wet bulb temperature of air (o
C, o
F)
The temperature difference between inlet and outlet water (ti - to) is normally in
the range 10 - 15o
F.

37. KSS/HZR-UTLT/2002 29
S
Y
S
T
E
M
BASIN
PUMP
FAN
AIR
S
Y
S
T
E
M
PUMP
FAN
BASIN
AIR
CROSS FLOW
INDUCED DRAFT
COUNTER FLOW
INDUCED DRAFT
TYPES OF COOLING TOWERS

38. KSS/HZR-UTLT/2002 43
ACID STORAGE
TANK
ACID TRANSFER PUMP
P 206
V 210
T 203 A T 203 B T 203 C
X 204
FAN X203
BASIN
CHANNEL
SUMP
PUMP P204
MAKE UP
WATER
FIREWATER
SUMP LEVEL CONTROLLER
SAND FILTER X207
SHMP
HEDP ZnSO4
Cl2
FROMSYSTEM
MAIL CELL O/LVALVE
T 202
COOLING
TOWER PFD

39. KSS/HZR-UTLT/2002 52
20 T213
20 P207 A/B
RAW WATER
STORAGETANK
STRONG ACID
CATION
EXCHANGER
22X202A/B/C22X201A/B/C
WEAKBASE
ANION
EXCHANGER
22V201A/B
DEGASSED
WATERTANK
22C201A/B
DEGASSING
TOWER
22B201A/B/C/D
AIR BLOWERS
22X203A/B/C
STRONGBASE
ANION
EXCHANGER
22X204A/B/C
MIXED BED
EXCHANGER
22T201
DM WATER
TANK
20T201
DM WATER
TANK
22P205A/B/C
20P205A/B
TO HPBOILERS
TO MPBOILERSNEUTRALISATIONPIT
22P203A/B
TO OWS
22P201A/B/C/D
HCL NaOH
AIR
HCL
NaOH
DM WATER PLANT
DM water stands for demineralized water. The minerals such as calcium, magnesium, that has tendency
to form scales of carbonates inside the tubing, has to be remov-ed before it is taken into use as a water
feed to the boiler. So there is a dedicated plant set up to remove the minerals.
As explained in the above diagram, the cations and anions of the water are removed separately.

40. COGENERATION PLANT(CO-GEN)
Cogeneration plant is the responsible for all the power and steam requirement of the plant. Cogen Plant has a total
capacity of producing 50MW power out of which approx. 30 MW is used by the plant and rest is either delivered to
DGVCL and consumed by the offices at the site, meets the power requirement of the ONGC Nagar.
INTRODUCTION:
Cogeneration means simultaneous generation both electrical and thermal energy
by raising a single primary heat source, thereby increasing the overall efficiency of
the plant. Cogeneration is one of the most powerful and effective energy
conservation techniques. In industries like refineries, petrochemical, fertilizer,
sugar etc, there is a requirement of both power and steam. LPG/CSU plant at
Uran needs power and steam. To meet this requirement a cogeneration plant was
setup. Hence this plant fulfills the requirement of both electrical power and steam
at a very low cost and high efficiency and reliability.
Cogeneration is of two types namely
 Copping up cycle
 Bottom up cycle
Copping cycle is one of in which heat requirement is attained by externally
firing the fuel. Whereas in bottom up cycle the heat requirement is fulfilled by
internal chemical reactions this cycle is used in medicine production.
Cogeneration plant at ONGC Uran is based on copping up cycle. The principle of
this plant is mentioned below:
PRINCIPLE:
Air from atmosphere is taken through an air filter and compressed in axial flow
compressor driven by the turbine. The compressor air enters into combustion
chamber where it is mixed with fuel (lean gas). During combustion its
temperature increases at constant pressure (process B to C) then it expands
mechanical energy by rotating the turbine. A major part of this energy is available
for the generator. Hence the thermal efficiency of the generator is very low Diesel
engine is used for initial cranking of the system. Once the turbine attains the
speed the contact is broken. However only 30% of the compressed air is used for
combustion and

41. Energy conversion and the rest of the air are used for cooling and sealing of the
net bas path (Turbine blades nozzles etc). The efficiency of the turbine can be
increased if the metallurgical part of the nozzle and blades are improved so that
the size of the compressor can be reduced for the same turbine
What is Cogeneration?
Cogeneration is the process whereby a single fuel source, such as natural
gas, is used to produce both electrical and thermal energy. By definition, an
onsite cogeneration system is more efficient than a utility operated central
power plant since thermal energy that would otherwise be wasted is
captured for use at the facility. The result is a much more efficient use of
fuel which can generate substantial savings for the end user. Conventional
electrical generation by a utility central plant is only about 35% efficient
compared to the 90% efficiency of an Intelligent Cogeneration Unit by IPS.
Because Intelligent Power Systems cogeneration equipment is so
efficient, most installations deliver significant energy cost savings.
If your facility has a need for thermal energy, in the form of heating and/or
cooling, you are a good candidate for a cogeneration system. Intelligent
cogeneration systems can provide Electricity, Cooling, Heating, Hot water
or Steam.

42. An Intelligent cogeneration system uses less fuel to produce the same
amount of energy -saving money and helping to protect the environment
Some Facts about Efficiency:
A typical facility will purchase electricity from the utility and fuel (gas or oil)
to power a boiler for hot water and heating. This process is inefficient and
expensive when compared to producing electrical and thermal energies
onsite through cogeneration with Intelligent Power Systems.
Transmitting power from a central power plant across long distances
carries the unfortunate price of a significant waste of power. By the time
electricity reaches your facility, much of the energy used to produce the
electricity is wasted. Electricity sent over the utility grid is generally
between 25% and 35% efficient - which means that as much as 75% of the
energy used by the utility to generate and transmit electricity is lost before
it even gets to you. By definition, this inefficiency flows through to you as a
customer in the form of higher electric rates.
An existing hot water heater (boiler) is typically anywhere from 50% to 80%
efficient, which wastes as much as one-half of the input fuel.
The poor overall efficiency of separate electric and thermal energy
production is bad news for the environment and for your profitability.

43. The good news is that Intelligent Power Systems equipment provides
electricity and hot water at a combined efficiency that approaches 90%.
Electricity created right where it is used, at your facility, has no detrimental
power line loss. More importantly, exhaust heat is recovered and provided
to your facility as useable energy. Overall, the process is more efficient,
which leads to savings for you, and the environment.
Depending on your circumstances, your savings can be substantial
compared to the conventional methods of meeting your energy needs.
Layout Diagram of the Co-Generation Plant

44. Power capacity of the gas turbine (GT):
Power- 3*19.6 MW
GE frame- 5 gas turbines
Steam capacity of the waste heat recovery boilers (HRSG):
Steam- 2*75+1*90 TON/HR
Waste heat recovery boilers
Plant demand for power and steam:
Power average - 41.0 MW/HR
Power (peak) - 50.0 MW/HR
Steam - 150 TON/HR
Export (with 3 GTS) - 5.0 MW/HR
Import (with 3 GTS) – NIL
This power and steam demand is easily met by the Co-generation plant as the
power turbines produce 3*19.6 MW= 58.8 MW
The steam produced by the HRSG is 2*75+1*90 TON/HR = 240 TON/HR
But sometimes one of the gas turbine may not be operational as mechanical
failure may occur, fuel gas line may leak, seizure of the compressor of the turbine
etc. The Co-generation plant is always connected to the power grid MSEB in the
case of failure of one of the turbines. Thus undisturbed power supply continues
Electric power to all the facilities and township at Hahira is supplied by
cogeneration power plant through three gas turbine generators. These turbines
are based on total energy conservation concept. The heat energy of gas turbine
exhausts is used for generation of high, medium and low pressure steam for use
in various process units. Excess power from the plant is wheeled to GEB grid for
revenue generation.

45. • How Cogen Works:
1. Two natural gas-fired combustion turbines drive generators to produce
electricity.
2. The hot combustion gases from each turbine pass through a
corresponding heat-recovery steam generator (HRSG) to produce
steam. The HRSGs contain duct burners to produce additional steam as
needed.
3. The high- and low-pressure steam from the HRSGs passes through a
single extracting/condensing steam turbine that sends heating steam
to the UW and produces electricity for the Madison area.
4. The exhaust steam is sent to a condenser and then cooled by cooling
towers. This process forms water that is reused.
5. Centrifugal chillers provide 20,000 tons of chilled-water capacity.
Electric-driven chillers use roof-mounted cooling towers for heat
rejection.
6. The steam heat and chilled water is used on the UW-Madison campus.
7. The electricity is sent to an adjacent substation and then to the
Madison area.

46. Cogeneration & CHP
Cogeneration (cogent) through combined heat and power (CHP) is the
simultaneous production of electricity with the recovery and utilization heat.
Cogeneration is a highly efficient form of energy conversion and it can achieve
primary energy savings of approximately 40% by compared to the separate
purchase of electricity from the national electricity grid and a gas boiler for onsite
heating. Combined heat and power plants are typically embedded close to the
end user and therefore help reduce transportation and distribution losses,
improving the overall performance of the electricity transmission and distribution
network (see district energy for more details). For power users where security of
supply is an important factor for their selection of power production equipment
and gas is abundant, gas-based cogeneration systems are ideally suited as captive
power plants (i.e. power plants located at site of use).
Benefits of Gas Engine CHP
The high efficiency of a CHP plant compared with conventional bought in
electricity and site-produced heat provides a number of benefits including
• On site production of power
• Reduced energy costs
• Reduction in emissions compared to conventional electrical generators and
onsite boilers
Heat Sources from a Gas Engine
The heat from the generator is available in from 5 key areas:
1. Engine jacket cooling water
2. Engine lubrication oil cooling
3. First stage air intake intercooler
4. Engine exhaust gases
5. Engine generator radiated heat, second stage intercooler
1, 2 and 3 are recoverable in the form of hot water, typically on a 70/90˚C flow
return basis and can be interfaced with the site at a plate heat exchanger.
The engine exhaust gases typically leave the engine at between 400 and 500˚C.
This can be used directly for drying, in a waste heat boiler to generate steam, or
via an exhaust gas heat exchanger combining with the heat from the cooling
circuits. 5. The heat from the second stage intercooler is also available for
recovery as a lower grade heat. Alternatively new technologies are available for

47. the conversion of heat to further electricity, such as the Organic Rankine Cycle
Engine.
CHP applications
A variety of different fuels can be used to facilitate cogeneration. In gas engine
applications CHP equipment is typically applied to natural gas
(commercial, residential and industrial applications), biogas and coal
gas applications.
CHP System Efficiency
Gas engine combined heat and power systems are measured based upon the
efficiency of conversion of the fuel gas to useful outputs. The diagram below
illustrates this concept.
Firstly the energy in the fuel gas input is converted into mechanical energy via the
combustion of the gas in the engine’s cylinders and their resulting action in the
turning of the engine’s crankshaft. This mechanical energy is in turn used to turn
the engine’s alternator in order to produce electricity. There is a small amount of
inherent loss in this process and in this example the electrical efficiency of the
engine is 40% (in reality GE Jenbacher gas engines are typically between 40-48.7%
electrically efficient).
THE MAINTENANCE PHILOSOPHY
The continuous operation of Hazira Gas Processing Complex is very critical for
keeping the sheels of downstream industries running. Therefore, the down time
costs are enormous as compared to the running costs or maintenance costs. In
order to keep the plant equipment and machinery in good shape and to achieve
highest level of equipment and system availability, a stringent maintenance
regime is adopted.
All the plant equipments are divided into three groups

48. i) Rotary Equipment - Includes all the rotating and reciprocating Eqpts.
Such as compressors, pumps, gear boxes,
engines, Motors, agitators, fans, conveyers
etc.
ii) Semi Rotary Eqpts.- Includes eqpts. Such as safety valves, control valves,
shutdown valves, MOV’s Manual operated
valves, NRV’s.
Iii) Static Eqpts. - Includes all eqpts. Such as pressure vessels, heat
Exchangers, columns, furnaces, boilers, flare
stacks, Piping networks.
The above three groups of equipments are maintained for its regular & long-time
needs through dedicated maintenance teams of;
a) Mechanical Discipline.
b) Electrical Discipline
c) Instrumentation/Electronics Discipline
Most of the planned and unplanned jobs are carried out during general shift
timings (8.45 a.m. to 6.15 p.m.) by the respective maintenance groups dedicated
to different units. However to cater to the emergencies and minor jobs during
odd hours, a round the clock shift maintenance teams of different disciplines are
also deployed. These teams are under the supervision of resident engineers
9RE’s), stationed at the plant itself for 24 hours.
This adds to the increased availability of maintenance people during holidays and
other odd hours. Apart from this all the key maintenance engineers have been
provided with telephones at their residences and can be called for duty within
very short span of time.
MAINTENANCE STRATEGIES
In order to keep the equipments and other facilities in proper condition so that
risk of equipment failure are minimized, the following maintenance strategies are
adopted.

49. A. PLANT TURNAROUND STRATEGY :
- The complete plant is subdivided into a number of units based on t their
operations and the units are further broken up into Trains (Process Streams).
- With continuous operation of the equipments and various systems, their
efficiency slowly reduces over the time. In order to bring these systems back
to original efficiency and also to attend to many accumulated maintenance
jobs, the units are shutdown, one by one, and repair/maintenance work is
carried out. This whole process of planned shutdown and turning around the
plant efficiency, is called plant turn around. The plant turn around are also
necessary to meet the statutory requirements of OISD standards and Factory
Act requirement, to inspect all the Pressure Vessels once in four years and get
the safety certificates from these agencies.
- Since the whole plant cannot be put under shut down to take up the turn
around jobs, a running plan strategy is adopted so that different units turn
around is staggered over a period of time.
- During the turn around, the unit is positively isolated from other process units
and all the rotary, semi static and static equipments are taken up for
repairs/overhauls/inspection etc. To accomplish this help from expert outside
agencies/OEM representatives, etc. is obtained. The planning and execution
of turn around work is closely monitored by the management. A typical plan
for carrying out the turn around, is placed at Annexure-II.
During turn around safety is ensured for safe working. After
depressurising/drawing the medium from vessels/tanks/etc. inert
gas/steam/plant air purging is carried out. Before man entry oxygen content
is measured (min 20%) in the equipment.
All nozzles to the equipment are blinded. Internal cleaning and inspection
carried out. Hydrotesting is normally done at 15 times design pressure for 30
minutes. After hydrotesting water is depressurized, drained and equipment is
dried up. IG purging is again carried out after deblinding of nozzles to ensure
oxygen content below 0.5%.
B. Rotary Equipment Maintenance Strategies :

50. The equipment critically can be described in the following categories;
i) Category -A+ Main process equipments of continuous operation
not having standby and whose outage results in
immediate production loss.
ii) Category –A Main process equipments of continuous operation
but having standby and whose outage results in
immediate production loss.
iii) Category- B Process and auxiliary equipment usually spared,
whose outage does not normally cause immediate
production loss.
iv) Category –C All process equipments required for intermittent
operation.
There are over 714 rotary equipments in HGPC. A summary of rotary
equipments is placed at annexure-I. Now depending upon the criticality of
the equipment the spares availability and maintenance needs are given due
priority.
All the rotary equipments are subjected to the following maintenance
regime.
i) Pro-Active Maintenance
a) Predictive Maintenance
b) Preventive maintenance
c) Overhauling
ii) Reactive/Breakdown Maintenance.
A brief about these maintenance techniques.
I) Pro-Active Maintenance
I) Predictive maintenance :
While the equipment is in operation any growing internal problem is detected by
trouble shooting techniques called CONDITION MONITORING TECHNIQUES.

51. The recommendations made based on these observations are immediately
implemented by the concerned maintenance group. This helps in preventing the
unplanned shutdown/breakdowns of the equipments and excessive damage to the
parts. This is achieved by system of regular monitoring of vibrations, noise level
and lube oil condition, of all the equipments. The frequency of these checks
depends on the criticality of the equipments.
iii) Time Bound Preventive Maintenance :
This is the oldest way of preventive maintenance. All the equipments are
subjected to monthly, quarterly, half yearly, annual preventive maintenance
checks as per the Preventive Maintenance Schedules prepared in advance.
III) Overhauling :
For all the major critical equipments, the overhauls are planned depending on the
running hours and the recommendations of Original Equipment Manufacturer
(OEM). For category A+ equipment’s these overhauls are clubbed with the plant
turn around. Sometimes the experts from OEM are called to carry out the
overhauling of the critical equipment’s.
II) Break down Maintenance :
In spite of regular preventive, predictive, and overhaul maintenance, there are a
few cases of break down maintenance. These break downs of equipment are
attended immediately, sometimes working overnight depending upon the
criticality of the equipment.
Each break down case is thoroughly analysed using defect analyses technique, so
that such occurrences can be avoided in future. In case of major break down the
help from OEM experts is also sought.
The above maintenance regime has been helpful in achieving nearly 100% system
availability and above 98% equipment availability.

52. MECHANICAL COMPONENTS USED INSIDE HAZIRA PLANT
PUMPS- Pumps are mainly used to transport liquid for various requirements of
the plants . there are 3 types of pumps used in hazira plant in order to pump fluid
1.Centrifugal pump-
The centrifugal pump creates an increase in pressure by transferring mechanical
energy from the motor to the fluid through the rotating impeller.
The fluid flows from the inlet to the impeller centre and out along its blades.
The centrifugal force hereby increases the fluid velocity and consequently
also the kinetic energy is transformed to pressure

53. Centrifugal pumps are used in cooling tower in order to pump to cooling water
for various cooling applications such as heat exchangers and centrifugal pumps
are also used in kerosene recovery unit
2.Reciprocating pump-
Reciprocating are widely used in hazira plant in GDU ,GSU in order to pump
MEDA and GLYCOL
3.Screw pump – screw pump is special type of pump used to handle slurry. Screw
plant is used in SRU

54. Gland Packing- gland packing is used to prevent of leakage of fluid being pumped
by the pump. That packing is generally used in centrifugal pumps
Mechanical seal- function of mechanical is seal is same as gland packing i.e to
prevent leakage of fluid to be pumped and that type of seal is generally used in all
types of pumps

55. Expansion Bellow- Expansion bellow is used to restrict thermal expansion in
pipes. Bellow is made of rubber material so that can easily contracted in case of
thermal expansion

56. Compressor- Hazira plant is a gas processing plant so it deals with gas and gas can
not be pumped by pumps so compressors are used . There are mainly 3 types of
compressors .compressors are used in inert gas plant,GDU,GSU
1.Reciprocating compressor -
SINGLE ACTING RECIPROCATING COMPRESSORS
Single acting compressor is used in GDU and GSU
reciprocating compressor is constructed of metal and has the following main
parts :-
1. THE CYLINDER
This is a metal tube-shaped casing (or body), which is generally fitted with a metal
lining called a 'cylinder liner'. The liner is replaceable when it becomes worn and
inefficient. The cylinder is also fitted with suction and discharge ports which
contain special spring loaded valves to allow liquid to flow in one direction only -
similar to check valves.
2. THE PISTON
The piston consists of a metal drive rod connected to the piston head which is
located inside the cylinder. The piston head is fitted with piston rings to give a
seal against the cylinder lining and minimise internal leakage. The other end of
the drive rod extends to the outside of the cylinder and is connected to the driver.
Modern industry generally used high power electric motors and gearing to
convert the rotating motion into a reciprocating action.
In a single acting compressor, the backward stroke of the piston causes a suction
which pulls in gas (or air) through the inlet valve. (The same suction action keeps
the discharge valve closed). On the forward stroke, the positive pressure
generated by the piston, closes the inlet valve and opens the discharge valve. The
liquid is displaced into the discharge system. Because the action is positive
displacement, a piston compressor can generate very high pressure and therefore
MUST NEVER be operated against a closed discharge system valve unless it is
fitted with a safety relief system in order to prevent damage to the compressor
and/or the driver and/or other downstream equipment.

57. Figure : Single Acting, Reciprocating Compressor (Simplified)
In the old days of piston pumps, the driver used to be (and still is in some cases),
high pressure steam which was fed to drive double acting cylinders by a system of
valves in a steam chest – like the driver of an old steam engine. The reciprocating
action is converted to rotation to drive the engine wheels.
(See photograph below).
Figure : – Conversion of Rotation to Reciprocation

58. DOUBLE ACTING-
This type of compressor operates in exactly the same way as the single acting
with respect to its action. The difference is, that the cylinder has inlet and outlet
ports at EACH END OF THE CYLINDER. As the piston moves forward, liquid is being
drawn into the cylinder at the back end while, at the front end, liquid is being
discharged. When the piston direction is reversed, the sequence is reversed. With
a double acting compressor, the output pulsation is much less than in the single
acting.

59. Screw compressors- A rotary screw compressor is a type of gas compressor
which uses a rotary type positive displacement mechanism. They are commonly
used to replace piston compressors where large volumes of high pressure air are
needed, either for large industrial applications or to operate high-power air tools
such as jackhammers.

60. The gas compression process of a rotary screw is a continuous sweeping motion,
so there is very little pulsation or surging of flow, as occurs with piston
compressors.
CENTRIFUGAL COMPRESSOR-
This type of compressor is used in inert gas plant
Centrifugal compressors, sometimes termed radial compressors, are a sub-class
of dynamic axisymmetric work-absorbing turbomachinery. The idealized
compressive dynamic turbo-machine achieves a pressure rise by adding kinetic
energy/velocity to a continuous flow of fluid through the rotor or impeller. This
kinetic energy is then converted to an increase in potential energy/static pressure

61. by slowing the flow through a diffuser. The pressure rise in impeller is in most
cases almost equal to the rise in the diffuser section.