GAIL summer training report......

GAIL Summer Training 2013

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S.No. Page

No.

1 Acknowledgement 02

2 Introduction 03

3 History 05

4 Integrated Offsite Plant & storage 06

5 Downstream 24

6 Upstream 36

7 Conclusion 55


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I would like to take this opportunity to thank everybody ,

who has helped me in course of undergoing training at

UPPC, GAIL , PATA from 10-jun-2013 to 08-jul-2013.

As a special mention I extend my sincere thanks to Mr.

John Kutty (HRD) & Shri. V.K.Purwar (SM, F&A) for their

kind support in helping me get settled in an entirely new

space to work and gain.

I also give my whole hearted thanks to Mr. Ajay Tripathi

(DGM-Mech.) ,Mr. G.C.Pandey(CM),Mr. Shrikant

Verma(Chief Er.),Mr. Neeraj(Er., GPU),Anil Nair(DM, Lib.)

for their guidance and supportive nature during the

training period and for the completion of report.

I am very thankful to Mr. H.N. Gupta(visiting faculty) for

enhancing my technical knowledge which made the

understanding of practical concepts easy.

At last I wish to extend my sincere thanks and gratitude

to all GAIL employees for their co-operation and ever

helping attitude thet helped me in my quest for complete

understanding of plant and various processes.

Navin Dixit

B.Tech(ME)


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GAIL (India) Limited, is India's flagship Natural Gas

company, integrating all aspects of the Natural Gas value

chain (including Exploration & Production, Processing,

Transmission, Distribution and Marketing) and its

related services. In a rapidly changing scenario, GAIL is

spearheading the move to a new era of clean fuel

industrialisation, creating a quadrilateral of green

energy corridors that connect major consumption centres

in India with major gas fields, LNG terminals and other

cross border gas sourcing points. GAIL is also expanding its

business to become a player in the International Market.

Today, GAIL's Business Portfolio includes -

* 7,700 km of Natural Gas high pressure trunk pipeline

with a capacity to carry 157 MMSCMD of natural gas

across the country

* 7 LPG Gas Processing Units to produce 1.2 MMTPA of LPG

and other liquid hydrocarbons

* North India's only gas based integrated Petrochemical

complex at Pata with a capacity of producing 4,10,000 TPA

of Polymers

* 1,922 km of LPG Transmission pipeline network with a

capacity to transport 3.8 MMTPA of LPG

* 27 oil and gas Exploration blocks and 3 Coal Bed

Methane Blocks


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* 13,000 km of OFC network offering highly dependable

bandwith for telecom service providers

* Joint venture companies in Delhi, Mumbai,

Hyderabad, Kanpur, Agra, Lucknow, Bhopal, Agartala

and Pune, for supplying Piped Natural Gas (PNG) to

households and commercial users, and Compressed

Natural Gas (CNG) to the transport sector

* Participating stake in the Dahej LNG Terminal and the

upcoming Kochi LNG Terminal in Kerala

* GAIL has been entrusted with the responsibility of

reviving the LNG terminal at Dabhol as well as sourcing

LNG

* GAIL Gas Limited, a wholly owned subsidiary of GAIL

(India) Limited, was incorporated on May 27, 2008 for the

smooth implementation of City Gas Distribution (CGD)

projects. GAIL Gas Limited is a limited company under the

Companies Act, 1956.

* Established presence in the CNG and City Gas sectors in

Egypt through equity participation in three Egyptian

companies: Fayum Gas Company SAE, Shell CNG SAE and

National Gas Company SAE.

* Stake in China Gas Holding to explore opportunities in

the CNG sector in mainland China

* A wholly-owned subsidiary company GAIL Global

(Singapore) Pte Ltd in Singapore


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GAIL (India) Ltd. (erstwhile Gas Authority of India Ltd),

India's principal gas transmission and marketing

company, was set up by the Government of India in August

1984 to create gas sector infrastructure for sustained

development of the natural gas sector in the country.

The 2800-km Hazira-Vijaipur-Jagdishpur (HVJ) pipeline

became operational in 1991. During 1991-93, three LPG

plants were constructed and some regional pipelines

acquired, enabling GAIL to begin its regional gas

distribution in various parts of India.

GAIL began its city gas distribution in Delhi in 1997 by

setting up nine CNG stations, catering to the city's vast

public transport fleet.In 1999, GAIL set up northern India's

only petrochemical plant at Pata.GAIL became the first

Infrastructure Provider Category II Licensee and signed

the country's first Service Level Agreement for leasing

bandwidth in the Delhi-Vijaipur sector in 2001, through

its telecom business GAILTEL. In 2001, GAIL commissioned

world's longest and India's first Cross Country LPG

Transmission Pipeline from Jamnagar to Loni.GAIL today

has reached new milestones with its strategic

diversification into Petrochemicals, Telecom and Liquid

Hydrocarbons besides gas infrastructure. The company has

also extended its presence in Power, Liquefied Natural Gas

re-gasification, City Gas Distribution and Exploration &

Production through equity and joint ventures

participations.


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&


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INTRODUCTION TO POWER PLANT

Power Plant in U. P. Petrochemical Complex comprises 3

Nos. Utility Boilers each having Steam Generating

Capacity of 120 TPH at MCR, at pressure 106 Kg/Cm2 (g)

510 o

C.

The Steam Generated from all these boilers is utilised

for production of Electrical Power in 2 Nos. of Turbo

Generators having Generating Capacity of 15.5

MW(Extraction type) & 25.6 MW(Condensing type) in

addition to meeting demand for process steam

requirement in different section of the complex . The high

pressure steam (106 Kg/Cm2

(g) ) produced from all the 3

boilers is connected to a common header from where

steam is fed separately to 2 nos. of steam turbines , serving

as prime mover to rotate 2 nos. of generators.

Normally, these boilers are meant for producing steam at

very high pressure (105 Kg/Cm2

) but depending on process

requirement this VHP steam is led down to high pressure

(40 Kg/Cm2

) , Low medium pressure (8.0 Kg/Cm2

) and Low

pressure at 4.0 Kg/Cm2

.


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UTILITY BOILER

A- Construction Details:

Make : M/s BHPV

Boiler Designation: 17.3 60

F VU 6 0 36

26 2

Where F- Stands for : Furnace

17.3 : Width of furnace in feet

26 :Length of furnace in feet

VU : Vertical Unit.

2 : Diameter of Bank tube in inch

36 : ID. of Lower drum in inch

Location : Semi out Door

Boiler Type : Natural Circulation, BI-Drum, Front

Wall Fired Forced Draft Furnace, Radiant Closed Bottom

Suitable for Oil/Gas Firing

Fuel : Rich Gas

: Lean Gas

: Combination of Blended

fuel oil & Rich Gas.

GENERAL DESCRIPTION OF BOILER


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The steam generator is a natural circulation water tube

design arranged for forced draft firing . Basically it is a

two drum vertically bent tube arrangement with water –

cooled furnace walls combined with convective boiler

bank surfface. The furnace is specifically designed to suit

for 10% excess air operation for gas firing . The complete

furnace section is of the welded wall type arranged as a

gas and pressure tight envelope which eliminates the

problem of casing corrosion and cumbersome refractory

maintenance , besides this provides structural rigidity for

the unit . The complete steam generator is of the bottom

supported design resting on concrete pedestals .

The conservatively sized upper and lower drums are

connected by the bank tubes . The steam drum is provided

with simple and efficient drum internals ,resulting in

high steam quality at all loads of boiler outputs .

Unheated downcomers are located in the boiler bank

sides.

The boiler bank tubes are arranged in line for best heat

absorption , minimum tube draft loss and for easy

inspection and cleaning . Required accessibility is

provided at the front & rear side of the boiler bank

convective surface . Adequate peepholes are also provided

to watch the flame.

The feed water from economiser is fed into the steam

drum. Circulation is maintained in the boiler bank

through the downcomers . From the bottom drum, water

flows through the heat absorbing furnace tubes and back

into steam drum .After separation of moisture in the steam


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drum the saturated steam flows into the superheater . The

superheater system has two sections. They are radiant

platen pendent section (arranged at the outlet of

furnace) and the final superheater adjacent to platen

section. A desuperheater is provided in-between the two

sections in the connective links for controlling the

superheater temperature over the wide load range . The

location and selection of superheater is so chosen that the

specified temperature of superheater achieved between 30

to 100% MCR load of the boiler .

The firing system consists of 4 No. of burners designed for

gas firing located in the font wall . Gas igniters are

provided for lighting the burner . The flame scanning

system is provided to monitor the main flame condition in

the furnace.

1 No. Forced draft fan with dual drive (motor + steam

turbine ) will supply the complete combustion air at the

required pressure for the boiler.

A bare tube in line economiser is provided as the last

heat recovery section.

The complete integral piping , valves and fitting, air

and gas ducting, all refractory and insulation materials

are provided.

Feed water is supplied to the steam drum from the feed

storage tank through feed line. The water side of the steam

drum is connected with lower drum through boiler bank

tubes . Furnace side walls inlet headers are supplied with

water from lower drum through supply tubes. The steam


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water mixture generated in the side walls are collected in

the side wall outlet headers and from where it is

discharged into the drum through a system of riser tubes.

Boiler water from the lower drum is fed into the front walls

through floor panels and discharged into steam drum as

steam water mixture . Likewise rear wall receives the boiler

water from lower drum and discharges to the steam drum.

B - ECONOMISER

The purpose of the economiser is to preheat the boiler feed

water before it is introduced into the steam drum, and to

recover some of the heat from the fuel gases leaving the

boiler.

The economiser is located in the second pass of the

boiler. Each section is composed of a number of parallel

tube circuits, arranged in horizontal rows. All tube

circuits originate from inlet header and discharge into

outlet header. Feed water is supplied to the economiser

inlet headerfrom FEED CONTROL STATION. The feed water

flow is upward or downward through the economiser that

is in counterflow to the hot fuel gases . Most efficient heat

transfer is thereby accomplished . Any chance of steam

generation within the economiser is eliminated . From the

outlet header the feed water is led to the drum.

Before starting up the boiler, the economiser should

be inspected externally and if necessary cleaned .

Especially if the installation is new, accumulation of

erection material is not unusual. Large debris should be


13

removed manually , followed by the washing down the

economiser banks by means of hose and water.

All joints in the economiser casing should be

examined occasionally for tightness in order that air in

filtration be kept to minimum. Insulation should be kept

in good condition.

C - SUPERHEATER

It is non drainable superheater , pendant type . The

superheater coils are suspended below the superheater

header.

No. of coils in Primary Super Heater (PSH ) - 13

No. of coils in Final Super Heater (FSH ) – 47

D - DESUPERHEATER

Desuperheater are provided in the steam line between PSH

& FSH to permit reduction of steam temperature when

necessary and to maintain the temperature at design

values within the limits.

Temperature reduction is accomplished by injecting

spray water into the path of the steam through a nozzle .

The spray water source is from the boiler feed water system.

It is essential that the spray water be chemically pure to

avoid contamination of main steam.

E- BURNER

4 nos. of Dual Fuel Burner per boilers are mounted on

common windbox . The windbox is designed in such a

manner that combustion air is uniformly distributed to


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all the burners. The combustion air entry to the burner is

through air register which is controlled by pneumatically

operated air cylinder. The dual Fuel Burner is Fitted with

1 No. of oil gun with steam atomiser tip assembly and 8

Nos. of Gas Poker Assembly.

The ignition system which is supplied along with

burner is capable of lighting liquid as well as gaseous fuel

on giving light up command to ignitor . Pilot flame

presence indication will be giving to the Burner

Management System .

In turn BMS will give a signal to open gas valve.

Thereafter Main Gas Flame will be detected by flame

scanners system. The flame scanners system shall provide

the continuous monitoring of the flame inside the furnace

which shall provide safety to the boiler.

In the event of Flame outage of individual burner the

flame monitoring system shall give signal to open or to

close gas valves together with other interlocks for safe

tripping of the burners isolation valves. In the event of all

four burners flame failure it will trip master fuel trip

valve. The flame monitoring system is provided with self

check facility so that spurious signals are eliminated and

reliable performance of the burner is guaranteed.

FD FAN :

Centrifugal Single Suction Fans are being used to handle

Clean Air . The spiral Casing converts part of kinetic

energy of the fluid into a Static Pressure . the Fan output is

usually controlled by adjustable inlet dampers or by


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varying the speed of the Fan either by means of hydraulic

couplings or by any suitable speed control device .The fan

is driven by motor/prime mover through coupling.

OPERATING PROCEDURES FOR BOILER

A - Preparation

1.Inspect the boiler prior to start.

Chack that (a) All foreign material has been removed.

(b) All doors are closed.

( c ) Starting equipments are ready.

(d) Interlocks are OK.

(e) Individual valves of burners are closed.

2.Close the Following Valves.

(a) Feed water regulating valve

(b)All drain valves of boiler, water walls and Economizer.

(c)Desuperheater control valves.

Open the Following Valves.

(a) Drum Air Vents.

(b)SH Air Vents.

(c)SH drain Valves

(d)Main steam line drain valve.

(e)Start up vent valve.

(f)Isolation valves on both sides of desuperheater


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control valve.

(g)All instrument and control connections to the boiler.

3.Check the Following Eqts for adequate Lubrication &

Cooling Water Flow.

(a)Boiler Feed Pump.

(b)FD Fan.

1. Put all automatic Control equipments on Manual

Control.

2. Check that all Control equipments are ready for service.

Manually operate all sequential trips and see that the

emergency fuel trips function properly.

B- LIGHT UP.

a) Take water into Steam Drum and maintain

Drum Level Normal.

b) Close Inlet vanes of FD Fan.

c) Open inlet damper of Air duct.

d) Open inlet damper of Chimney .

e) Start FD Fan.

f) Increase Air Flow more than 30% of MCR.

g) Light the Lower burner one at a time .

h)Close Drum Air vents when Drum pressure reaches 2

Kg/Cm2

.


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i) Take other Burners in line and raise the drum

pressure slowly as per start up curve

j) Connect the boiler with the Header when steam

pressure is 105 kg/Cm2

.

k) Close main steam drain and SH drains.

l) Inject Chemicals into D/A and drum to maintain

C- SHUT- DOWN

a) Start reducing boiler load gradually. Reduce the

firing rate in line with reducing the steam flow.

b) Shut-Down the Burners one at a time, Starting with

the upper elevation .

c) All fires should be out when the boiler is off the line.

d) Run the Fans for at least 10 minutes after

Shutting down.

e) Maintain the water level in drum .

f) When the drum pressure comes down to 2 Kg/Cm2.


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STEAM TURBINE

A turbine is a rotary engine that extracts energy from a

fluid flow and converts it into useful work. The simplest

turbines have one moving part, a rotor assembly, which is

a shaft or drum with blades attached. Moving fluid acts

on the blades, or the blades react to the flow, so that they

move and impart rotational energy to the rotor. Early

turbine examples are windmills and water wheels.

Gas, steam, and water turbines usually have a casing

around the blades that contains and controls the working

fluid. Credit for invention of the steam turbine is given

both to the British Engineer Sir Charles Parsons (1854–

1931), for invention of the reaction turbine and to

Swedish Engineer Gustaf de Laval (1845–1913), for

invention of the impulse turbine. Modern steam turbines

frequently employ both reaction and impulse in the same

unit, typically varying the degree of reaction and impulse

from the blade root to its periphery.

A steam turbine is a mechanical device that extracts

thermal energy from pressurized steam, and converts it

into rotary motion. It has almost completely replaced the

reciprocating piston steam engine primarily because of its

greater thermal efficiency and higher power-to-weight

ratio. The steam turbine is a form of heat engine that

derives much of its improvement in thermodynamic

efficiency through the use of multiple stages in the

expansion of the steam, which results in a closer approach

to the ideal reversible process. There are several

classifications for modern steam turbine.

http://en.wikipedia.org/wiki/Engine

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Fluid

http://en.wikipedia.org/wiki/Windmill

http://en.wikipedia.org/wiki/Water_wheel

http://en.wikipedia.org/wiki/Gas_turbine

http://en.wikipedia.org/wiki/Steam_turbine

http://en.wikipedia.org/wiki/Water_turbine

http://en.wikipedia.org/wiki/Charles_Algernon_Parsons

http://en.wikipedia.org/wiki/Gustaf_de_Laval

http://en.wikipedia.org/wiki/Thermal_energy

http://en.wikipedia.org/wiki/Steam

http://en.wikipedia.org/wiki/Reciprocating_engine

http://en.wikipedia.org/wiki/Steam_engine

http://en.wikipedia.org/wiki/Power-to-weight_ratio

http://en.wikipedia.org/wiki/Power-to-weight_ratio

http://en.wikipedia.org/wiki/Heat_engine

http://en.wikipedia.org/wiki/Thermodynamic_efficiency



http://en.wikipedia.org/wiki/Reversible_process_%28thermodynamics%29


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Type of Turbines-

(A)Based on operation

Impulse Turbines: It has fixed nozzles that orient the

steam flow into high speed jets. These jets contain

significant kinetic energy, which the rotor blades,

convert into shaft rotation as the steam jet changes

direction. A pressure drop occurs across only the

stationary blades, with a net increase in steam

velocity across the stage. As the steam flows through

the nozzle its pressure falls from inlet pressure to the

exit pressure (atmospheric pressure, or more usually,

the condenser vacuum). Due to this higher ratio of

expansion of steam in the nozzle the steam leaves the

nozzle with a very high velocity. The steam leaving

the moving blades is a large portion of the maximum

velocity of the steam when leaving the nozzle. The loss

of energy due to this higher exit velocity is commonly

called the "carry over velocity" or "leaving.

Reaction Turbines: In this the rotor blades themselves

are arranged to form convergent nozzles. This type of

turbine makes use of the reaction force produced as

the steam accelerates through the nozzles formed by

the rotor. Steam is directed onto the rotor by the fixed

vanes of the stator. It leaves the stator as a jet that

fills the entire circumference of the rotor. The steam

then changes direction and increases its speed


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relative to the speed of the blades. A pressure drop

occurs across both the stator and the rotor, with steam

accelerating through the stator and decelerating

through the rotor, with no net change in steam

velocity across the stage but with a decrease in both

pressure and temperature, reflecting the work

performed in the driving of the rotor.

(B)Based on Steam Supply and Exhaust Conditions

Noncondensing or backpressure turbines are most

widely used for process steam applications. The

exhaust pressure is controlled by a regulating valve to

suit the needs of the process steam pressure.

Condensing turbines exhaust steam is in a partially

condensed state, typically of a quality near 90%, at a

pressure well below atmospheric to a condenser.

In a reheat turbine, steam flow exits from a high

pressure section of the turbine and is returned to the

boiler where additional superheat is added. The

steam then goes back into an intermediate pressure

section of the turbine and continues its expansion.

In an extracting type turbine, steam is released from

various stages of the turbine, and used for industrial

process needs or sent to boiler feedwater heaters to

improve overall cycle efficiency. Extraction flows may

be controlled with a valve, or left uncontrolled.

Induction turbines introduce low pressure steam at

an intermediate stage to produce additional power.

http://en.wikipedia.org/wiki/Steam_quality

http://en.wikipedia.org/wiki/Feedwater_heater


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Principle of Operation

The motive power in a steam turbine is obtained by

the rate of change in momentum of a high velocity jet of

steam impinging on a curved blade which is free to rotate.

This jet of steam impinges on the moving vanes or blades,

mounted on a shaft. Here it undergoes a change of

direction of motion which gives rise to a change in

momentum and therefore a force. The interior of a turbine

comprises several sets of blades. One set of stationary

blades is connected to the casing and one set of rotating

blades is connected to the shaft. The sets intermesh with

certain minimum clearances, with the size and

configuration of sets varying to efficiently exploit the

expansion of steam at each stage.

Operation and Maintenance

When warming up a steam turbine in order to avoid

slugging nozzles and blades inside the turbine with

condensate on start-up which can break these components

from impact. The blades were designed to handle steam,

not water. The main steam stop valves have a bypass line to

allow superheated steam to slowly bypass the valve and

proceed to heat up the lines in the system along with the

steam turbine..

Steam Turbine Components

The components of Steam Turbine are:

Blades

Rotors


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Casings

Seals

Nozzles.

Steam turbines consist of circularly distributed stationary

blades called nozzles which direct steam on to rotating

blades or buckets mounted radially on a rotating wheel.

In a steam turbine nozzles apply supersonic steam to a

curved blade. The blade whips the steam back in the

opposite direction, simultaneously allowing the steam to

expand a bit.Typically, the blades are short in proportion

to the radius of the wheel, and the nozzles are

approximately rectangular in cross section.

STEAM TURBINE GENERATOR (STG # 1)

Vendor : M/s BHEL Hyderabad.

Type : EHNG 40/32 – 3.

Capacity : 15.5 MW.

No. of Stages : 17

HP (Impulse +Reaction) : 1 + 6

LP (Impulse +Reaction) : 1 + 9

Turbine Speed : 8500 rpm.

Reduction Gear Output Speed 3000 rpm.

Steam Pressure : 105 Kg/Cm2


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Steam Temperature : 500 o

C

Wheel Chamber : 75.8 Kg/Cm2

Extraction Pressure : 41.0 Kg/Cm2

Extraction Flow : 55 TPH

Exhaust Pressure : 5.00 Kg/Cm2

Exhaust Flow : 75 TPH

Maxm

Steam Flow : 130 TPH

STG # 2

Vender : M/s BHEL

Type : Full Condensing

Capacity : 25.6 MW

No. of Stages : 48

Impulse : 1

Reaction : 47

Turbine Speed : 3000 rpm

Steam Pressure : 105 Kg/Cm2

Steam Temperature : 500 o

C

Steam Flow : 91 TPH (for full Load)


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POWER GENERATION THROUGH STGs-

Presently the Maximum requirement of Electrical power for

the complex is around 32 MW.

This demand of 32 MW power requirement in met by 2

Steam Turbo Generators .

2 Nos. of Generators having capacity of 15.5 MW & 25.6 MW

are separately coupled with steam turbines, serving as

prime movers.

Power Generated by these Generators is at 11 KV . It is

further stepped up to 33 KV through transformers which is

synchronised with the 33 KV grid.

This power at 33 KV is then stepped down through the

transformers to 6.6 KV & 415 KV to run HT motors and L.T.

motors of the complex.


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&


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DESCRIPTION OF HDPE PROCESS BRIEF

Catalyst system

To initiate any polymerization reaction, catalyst is

necessary. The catalyst system for Polyethylene is based on

„Ziegler-Natta catalysts‟. This system consists of a catalyst-

co catalyst pair. Main catalyst - Halides or other

derivatives of transition metals in group IV-VIII of

periodic table. (In our plant it is the PZ catalyst which is

based on ticl4). Co catalyst - Alkyls of Group I-III metals.

(In our plant it is TEAL i.e. Try Ethyl Aluminum)

Polymerization :

Raw materials

The raw materials used in the production of HDPE and

their roles is as,

Ethylene – This is the basic monomer which forms the

backbone of HDPE chain.

Catalyst – This initiates the polymerization reaction.

Hydrogen – This helps in termination of polymer chain.

Hence this controls the molecular weight. So Hydrogen is

used to control MFR. The control of Hydrogen feed is done

based on Hydrogen / Ethylene ratio. This ratio varies as

per grade because each grade has different MFR.

Butene-1 / Propylene – These two are co-monomers. They

take part in reaction along with Ethylene and form side

branches. The loading of co-monomer decides density of

polymer.


27

Hexane – This is inert reaction medium. This helps in

removal of enormous amount of heat of polymerization.

Operation

The polymerization reaction is highly exothermic. It gives

out enormous amount of heat. This heat needs to be taken

out immediately and effectively to avoid run away

reactions. The reactors have three modes of heat removal,

Overhead coolers – the un-reacted gas from reactor is

taken to overhead cooler. The hexane content in the gas is

cooled and separated. The cooled gas is again bubbled

from the bottom of the reactor. Along with agitators, this

helps in preventing the slurry from settling. The condensed

hexane is also fed back to the reactor. Slurry coolers – at

high loads, some portion of slurry is also taken out from

the bottom of the reactors. It is circulated through coolers

and fed back to the reactors. Jackets - Each reactor has

jacket with cooling water running through it.

Feed of Hydrogen to the reactor is most critical part of the

polymerization. It needs to be accurately controlled. Each

reactor is equipped with on line Process Gas

Chromatographs (PGC) for this purpose. A small sample of

un-reacted gas from the reactor is continuously fed to the

PGC.

PGC analyses the Hydrogen and Ethylene content of the

stream. Special programs on the MAPS convert the % to

ratio of Hydrogen to Ethylene.

Hydrogen valve opening is controlled by MAPS Programme


28

Separation

The polymer slurry, after degassing, is fed to the

centrifuge. The centrifuge separates the polymer powder

from hexane. The wet cake of polymer is fed to dryer. The

hexane decanted contains some amount of low polymer

formed during polymerization and is called mother

liquor. The wet cake is dried in rotary dryer. Some portion

of the mother liquor is recycled back to the reactors.

Remaining mother liquor is sent to hexane recovery

section of purification of hexane.

Drying

The wet cake from centrifuge is fed to rotary dryer. It has

hexane content of 30% by weight. $Dryer uses two drying

media, Low pressure steam running through the inner pipe

inside the dryer. This is indirect heating. Hot nitrogen fed

to the dryer coming in contact with powder. This is direct

heating. $The hot nitrogen coming from dryer is cooled

and scrubbed with hexane to wash off any entrained

powder. It is again heated and fed back to dryer. The dry

powder (with hexane content of 0.2% wt or lower) is

conveyed to hopper by nitrogen.


29

Extruder

The dry powder from dryer is taken to a intermediate

hopper. Before sending to extruder, various additives are

mixed with the powder. The blend of powder and additives

is melted in the extruder barrel. The melt is forced

through a die having number of holes to give thin noodle

like strands. A cutter assembly, rotating very close to the

face of the die, cuts the strands to pellets. The pellets are

conveying by air to various storing silos. From silos, the

pellets are sent for bagging

Hexane recovery

The mother liquor decanted from centrifuge is fed to this

section. The low polymer in mother liquor is separated in a

stripper. Pure hexane vapors from stripper top are

recovered, condensed and dehydrated. The pure hexane is

stored in tanks and put in re-use. The low polymer

concentrate recovered from stripper bottom is subjected to

flashing to recover maximum hexane from it. The low


30

polymer is then dumped to pits. After solidification, low

polymer blocks are cut out. These are processed in flaker

plant to form flakes.

Utilities

Various utilities / auxiliary services used in the plant are,

Brine system

HP steam

LP steam

Nitrogen

Process water

Instrument air

Cooling water

Electric power

Caustic soda

MECHANICAL SEAL-

General Classifications

Seals may be generally sub-divided into :

(A)Dynamic Seals

(B)Static Seals

The primary purpose of seals is to prevent ingress of

unwanted contaminants and to prevent egress of any


31

internal sustance whether it be gas or liquid for

containment or lubrication. The majority of applications

are in areas where the substance retained is a lubricant

and the purpose of the seal is to ensure that it stays where

it is put.

In simple terms, external seals have two main functions: to

prevent lubricating oil from leaking out, and, to prevent

dust, water, and other contaminants from entering the

bearing. When selecting a seal, the following factors need

to be taken into consideration: the type of lubricant (oil

or grease), seal peripheral speed, shaft fitting errors, space

limitations, seal friction and resultant heat increase, and

cost.

Dynamic seals can be used with either rotary or

reciprocating motions. A separate group of dynamic seals

comes under the heading “others”. These seals are indeed

statistically attached to the counterfaces and the limited

motion is fully taken up by the seal material itself.

Examples of the latter would be bellows and the

diaphragms.

Apart from Static and dynamic, the Sealing devices for

rolling bearings fall into two main classifications:

(a)Contact Seals.

(b)Non-contact Seals.

Contact seals:

Contact seals accomplish their sealing action through the

contact pressure of a resilient part of the seal (the lip is


32

often made of synthetic rubber) and the sealing surface.

Contact seals are generally far superior to non-contact

seals in sealing efficiency, although their friction torque

and temperature rise coefficients are higher.

Non-contact seals:

Non-contact seals utilize a small clearance between the

shaft and the housing cover. Therefore friction is

negligible, making them suitable for high speed

applications.

Polymer formation diagram-

Catalyst

preparation

Polymerization

Separation &

Drying

Pelletizer

Hexane

recovery

Low polymer

handling

Flaker unit

Catalyst

(PZ, AT)

Catalyst soln

Raw material like C2,

H2, Bu-1, Propylene

Polymer slurry

Mother

liquor

Mother

liquor

recycle

Dry powder

Pure and dry

hexane

Crude hexane

from IOP

LP pits

LP wax to flaker

LP Flakes

G-Lex pellets for bagging

Molten wax

Recovered

hexane


33

LLDPE

REACTION AREA

Solvent (SH) is recycled to the reaction area from the

reflux drum of the HB Column in the Solvent Recovery

Area. The temperature of this solvent stream is

approximately 175o

C and is cooled to 31o

C by a series of

heat exchangers which includes the Process Exchanger

and the Recycle Coolers. First, cooling in the Process

Exchanger will reduce the recycle solvent temperature to

approximately 155o

C. The heat from this stream is used to

warm the feed to one of the distillation columns thereby

increasing the energy efficiency of the operation. Further

cooling is provided with a Recycle SH Air Cooler in series

with a Recycle SH water Cooler. The use of Recycle SH Air

Cooler minimizes cooling water demand.

There are two reactor modes which are normally used.

1) #1 Reactor mode

2) 3→1 Reactor mode

The polymerization reaction is highly exothermic,

releasing approximately 93.7 MJ of heat per kg mol of

monomer or comonomer reacted. All reactor modes

operate adiabatically and therefore there is a substantial

increase in the temperature of the reaction mixtures

through the reactor system.

RECYCLE AREA


34

The solvent and steam condensed in the Solvent

Vapour Condenser from the overhead of the Stripper is

collected in a Decanter. In order to facilitate water

removal from the solvent, the Decanter is designed with a

coalescer. Solvent leaving the Decanter is relatively dry,

containing dissolved water but no separate liquid water

phase. The saturation level for water in SH at 35oC is

about 100 ppm by weight. This stream is pumped to the LPS

Hold Up Tank (HUT) in the LPVR area.

Polymer formation flow diagram –


35

EXTRUSION \FINISHING AREA

Polymer from the bottom of the LPS is fed directly into the

feed hopper of the Main Extruder. The function of the Main

Extruder is to pressurize the polymer and feed it to the Melt

Cutter or Pelletizer, which produces uniform pellets of the

polymer.

In the feed section of the Main Extruder, there is a

tendency for gas to build up at the rear of the first

extruder screw flite. On low MI resins, at high screw speeds,

the vapour pocket formed Solid additives can be added to

the main extruder with the aid of the satellite extruder.

The Melt Cutter consists of a die plate on which rotates a

set of knife blades which cut the emerging polymer strands

into uniform sized pellets. A flow of water circulates

through the cutter housing to first quench and then

convey the cut pellets away from the cutter.

From the melt cutter, the pellets are conveyed to a

Delumper that segregates large lumps of polymer into a

waste hopper. Generally, large lumps are produced only

during startup of the extruder/cutter system. The Melt

Cutter consists of a die plate on which rotates a set of knife

blades which cut the emerging polymer strands into

uniform sized pellets.

BUTENE-1

process can be divided into following areas:

1. Catalyst section. 2. Reaction section. 3. Evaporation section.


36

4. Distillation section. 5. Storage section.

FLOW DIAGRAM OF BUTENE-1


37

&


38

GAS SWEETENING UNIT

„Sweetening‟ means removal of acid from gases like H2S &

CO2. The HVJ gas is received from ONGC contains CO2

(5.52% by volume) & H2S (4ppm). The gas forms the

feedstock to the C2-C3 recovery unit where cryogenic

conditions prevail & if the CO2 component of the gas is not

received. It will freeze at such a low temp.

Gas sweetening plant uses DEA (Di Ethanol Amine) as a

solvent for removing CO2 in the natural gas by chemical

absorption.

ABSORPTION SECTION

Natural gas coming from HVJ is treated in two parallel

high pressure absorbers. The gas is fed to the absorber

column at a pressure of 52 kg/cm2 & temp 30 C. This gas is

counter currently treated with DEA solvent (40% by

weight) which is fed from the top of the column. The

absorber column contains 30 valve trays. The treated gas

leaves from top of the column at 45 C & contains less then

50 ppm of CO2.

TREATED GAS WATER WASH & COOLING

The treated gas from absorber column is counter

currently washed with water in water wash column

equipped with ball rings to remove the DEA carried over

the gas. The DEA solution in water is removed from the

bottom of this column & sent

to the rich amine flash drum. The treated gas is cooled to

40 C & leaves the unit at pressure 50 kg/cm2.


39

RICH AMINE CIRCUIT:

The rich amine from the absorber bottom & the water wash

column are sent to rich amine flash drum. The rich amine

flash drum is operated at 6.5 kg/cm2 & 70 C. Most of the

hydrocarbons are co-absorbed in DEA solution is removed

in this drum & sorted to the plant fuel gas system.

AMINE REGENERATION:

The rich amine solution from the flash drum enters the

regenerator column through the rich lean amine

exchanger at 110 C. In the regenerator the solvent DEA is

stripped off CO2 using low pressure steam in the column

reboilers. The column has 21 valve trays. The top two trays

are used to minimize DEA carryover with the CO2. This

column operates at 2kg/cm2. The top temp is 97 C & the

temp at the bottom is around 126 C. The lean amine is

withdrawn from bottom of the column & is sent to storage

after being cooled to 45 C in rich lean amine exchanger &

then by cooling water.

Vapors from the top of the regenerators are condensed in

the regenerator overhead condenser & taken in to

Regeneration reflux drum. The uncondensed gases mainly

CO2 are vent to atmosphere at a safe location & the

condensed liquid is pumped back as reflux to the column.

AMINE STORAGE:

The lean amine from regenerator is sent to amine storage

tank from where it is pumped to the absorbers. The amine


40

tank is blanketed with N2 to prevent solvent degradation

with O2.

AMINE FILTERATION:

A stream of stored amine solution is continuously sent to

the filteration package by amine filteration pump. DEA

solvent filteration is required to remove all the dissolved

hydrocarbons, scales & solvent degradation products that

can cause corrosion & foaming.

Levels of filteration may be as-

a) Precoat filter consisting of cellulose

b) Activated carbon filter which removes corrosion

products

c) Cartridge filter which removes any carbon particles

ANTIFOAM INJECTION PACKAGE:

Antifoam facilities are provided to overcome foaming

problems in the absorber. The antifoam solution is an

aqueous solution of silicon oil. This is injected to the

suction of amine charge pumps.

AMINE DRAIN RECOVERY:

All the solvent drains are removed in an underground

amine sump pump.

C2/C3 RECOVERY UNIT

C2/C3 Recovery plant has been designed by Engineers

India Limited. In this plant C2/C3 fraction of the feed gas

is recovered under cryogenic conditions by Turbo


41

Expander process. The C2/C3 product from this unit forms

the feedstock of the gas cracker unit.

The process comprises of the following section:

FEED GAS COMPRESSION:

The sweetened gas is recovered from the Gas Sweetening

Unit at 50 kg/cm2 and 40 C in the field gas Knock Out

Drum where the entrapped liquids are removed. The gas is

now compressed to 55 kg/cm2 in feed gas Expander

compressor.

FEED GAS DRYING/REGENERATION:

The compressed gas is cooled down to 37 C using cooling

water in Feed Gas Compressor discharge cooler and further

down to 18 C by the outgoing lean gas in the feed/lean gas

exchanger. The condensed moisture from the gas is

removed in moisture separator. The gas is now saturated

with water that is removed in a dryer to a water dw point

of -100 C using molecular sieves as desiccants.

There are two dryers out of which one is in drying

mode and the other is either a standby or in regeneration

mode. The drying period is around 12 hours and the

regeneration is also 12 hours.

A part of the lean gas from the first stage discharge of the

lean gas compressors is heated to 320 C in a gas fired

heater and this hot gas is used for regeneration of the

dryers.


42

FEED GAS CHILLING/SEPARATION:

The feed gas enters the feed gas chiller #1 where it is

cooled down to -32 C by the separator 1 & 2 liquids and

the lean gas. The gas is further chilled down to -38 C in

the demethaniser side reboiler.

The gas is again chilled in feed gas chiller 1 to about -

55 C to -60 C. The partially condensed feed gas at this

stage is taken to the separator 1 where the condensed

liquid is separated and sent to chiller 1 for cold recovery.

The liquid is then fed to the demethaniser column.

The uncondensed vapor from the separator 1 are cooled

to -18 C by the outgoing lean gas in feed gas chiller 2.

These vapours are now taken to Separator 2 where again

the condensed liquid is separated. Cold from this liquid is

recovered in feed gas chiller 1. It is then mixed with the

Separator 1 liquid and this is fed to the demethaniser

column on tray 18.

FEED GAS EXPANSION:

The overhead gas from separator-2 is expanded

entropically in the feed gas expander to around 22

kg/cm2 and the temp of the gas drops to -98 C. Due to this

chilling, there is further condensation of the gas. This

vapour liquid mixture is fed to the demethaniser column

on the 8th

day .The work available from the isentropic

expansion of the Separator-2 vapour is used to compress

the feed gas.


43

FRACTIONATION:

The reaction consists of a demethaniser column which

serves to recover C2-C3 product from (i) Separator 1 & 2

liquids received at -68 C and (ii) feed gas expander

overhead vapours received at -98 C.

This separates almost all the methane from the gas. It

consists of 36 valve trays and one chimney tray for

supplying feed to side reboiler. The column reboilers chill

down the feed gas and in turn recover reboiler duty. The

overhead vapours are chilled from -98 C to -102 C and

condensed in the demethaniser overhead condenser by the

cold gas from the demethaniser over expander outlet -117

C. The demethaniser overhead vapour is expanded from

21.5 kg/cm2 to 12 kg/cm2 and due to this gas is chilled to

-117 C. This cold methane is the major source of

refrigeration in the unit.The bottom product from the

demethaniser column is the C2/C3 product, which is

pumped as feed to cracker unit or sent to storage. The

recovery of C2 is around 90%.

LEAN GAS COMPRESSION:

The lean gas after giving away its cold to a series of

exchanger (viz. Feed Gas Chiller-2, Feed Gas Chiller-1,

Feed/Lean Gas Exchanger) gets heated to 25 to 30 C and is

first compressed from 10kg/cm2 in the demethaniser

overhead expander compressor and is further compressed

to 55 kg/cm2 in a 2-stage gas turbine driven Lean Gas

Compressor. It is cooled to 40 C and then sent back to HVJ

pipeline. About 36 ton/hr of lean gas is drawn from first


44

stage discharge of the lean gas compressor for dryer

regeneration. This gas is then compressed to 55 kg/cm2 in

a steam turbine driven Residue Gas Compressor and is

then sent to Lean Gas Compressor discharge header.

A part of gas from the first stage Lean Gas Compressor

discharge is also taken for internal fuel consumption of

the unit.


45

GAS CRACKER UNIT(GCU)

The Gas cracker unit is a part of the U.P.Petrochemical

complex. The Gas Cracker unit comprises of the Hot section

(cracking furnace /cracked gas compressor) and Cold

section (The Ethylene recovery unit). The C2/C3

hydrocarbon is cracked and compressed in Hot section

and Ethylene, Hydrogen, Propylene, C4mix, C5+ are

separated (distilled) in Cold section. Ethylene and

Hydrogen are main product, where as Propylene, C4 mix

and C5+ are separated as by products. The waste heat from

the cracker gas effluent is used to produce VHP steam at

105 Kg/cm2 and 510O

C, which is subsequently used for

running the turbine of gas compressors and heat

requirement of the GCU plant.The breaking of molecule to

yield more useful products is called cracking. Cracking

requires high temperature to initiate it and is

endothermic. The heat is supplied by the direct firing of

fuel gas in the furnace.

Gas cracker Plant mainly consist of following units

a) Furnace/ Quench Tower

b) Cracked Gas drying

c) Dispersed Oil Extraction process.

d) Demethaniser

e) Hydrogen unit (PSA)


46

f) De-ethaniser

g) C2 Hydrogenation

h)Ethylene Tower

i) Ethylene Product Distribution

j) DeButaniser

k) Propylene Stripper

FURNACES

The pyrolysis furnace area consists of four 24 W 144 type

furnaces for 300,000 MTA ethylene capacity based on 8000

hours / year. The furnaces are both wall and floor fired

and utilize gas fuels.As off-set connection section recovers

waste heat from the flue gases leaving the radiant section

of the furnaces. The fire gases are finally discharged to

atmosphere via an induced draft fan and a stub stack.

The cracked gases leaving the radiant coils are quenched

in a series of exchangers before being routed to the quench

water tower.

The convection section of the pyrolysis furnaces contains

the following services:

a) Hydrocarbon (HC) Preheat - I.

b) Boiler Feed Water (BFW) Economizer.

c) HC Preheat II

d) High Pressure Superheated Steam (HPSS).

Hydrocarbon + Dilution Steam (HC + DS).


47

Process Description

FEED VAPORIZATION:

C2/C3is received from C2/C3 recovery unit of GPU at 0 C

and 22 kg/cm2 abs. It is flashed to around 10 kg/cm2 abs

whereby it gets cooled at -26 C. It is then first heated by the

propylene refrigerant and then by quench water and LP

steam to around 80 C.

CRACKER FURNACE:

Dilution steam is mixed with C2/C3 vapor in the ratio of

0.3:1 and fed to convection section of furnace.

The dilution steam has two functions:

a) Reduce the hydrocarbon partial pressure thereby

increasing yield of ethylene.

b) Reduce the rate of coke formation thereby increasing

the furnace run length.

In the convection section of furnace the feed gets heated to

around 650 C by heat exchange with fuel gas. It is then

fed to the radiant section of furnace where cracking of

C2/C3 takes place. There are 5 furnaces each having

capacity of 1,00,00 TPA. Each furnace has 12 W type

radiant coils having total length of 44m. The

temperature at the exit of the radiant coil is 850 C. the

conversion per pass for ethane is around 75% by weight

while that for propane is 93%. The hot gases are cooled to

around 350 C by generating VHP steam in USX and TLX


48

exchangers. It is further cooled to around 200 C in TLX-2

by heating boiler feed water.USX and TLX are heat

exchangers.

QUENCH WATER AND DILUTION STEAM:

The hot gases are then quenched and cooled to around 40

C by direct contact with water in quench tower. Some light

fuel oil present in cracked gas gets condensed. This is

separated from water in oil water separator and pumped

to off sites. The steam, which gets condensed in quench

tower, is pumped to process water treatment unit to remove

impurities such as oil and suspended solids. The treated

water is pumped to dilution steam is generated and used

in the process.

CRACKED GAS COMPRESSION & DEHYDRATION:

The cooled cracked gas is compressed from 1.4 kg/cm2 abs

to 26 kg/cm2 abs in a 4-stage steam turbine driven

compressor having rated power of 18 MW. Inter stage/after

stage coolers and KOD are provided to cool the compressed

gas and separate the condensed liquid (fuel oil). H2S and

CO2 present in cracked gas are removed in caustic tower

between 3rd

and 4th

stages of compression. The cracked gas

after the 4th

stage is cooled by cooling water and propylene

refrigerant and

then routed to dehydrators where the moisture in cracked

gas is reduced to <1ppm by volume


49

DEMETHANISER:

The dried gas is cooled in demethaniser section to around

-100 C by different levels of propylene and ethylene

refrigeration. It is further cooled to -135 C by vapors from

expander compressor. The condensed liquids are

fractioned in demethaniser system. The C2+ liquids are

sent to deethaniser while the vapors (mainly CH4 and H2)

are routed to expander where they are expanded from 21

kg/cm2 abs in a 3-stage machine. The vapors after giving

cold in demethaniser section are compressed and routed

to fuel gas system.

The polybed Pressure Swing Adsorption (PSA) unit for

hydrogen purification is designed to deliver a constant

and continuous flow of high purity hydrogen product

stream. PSA employs molecular sieve type adsorbent to

purify the crude hydrogen stream supplied from

demethaniser system. The adsorber operates on an

alternating cycle of adsorption and regeneration with

adequate beds always available for service.

ETHYLENE RECOVERY UNIT:

In deethaniser, ethane/ethylene mixture gets separated

from C3+. The ethane/ethylene mixture (top product from

deethaniser) is fed to C2 hydrogenation section where

acetylene is converted to ethylene/ethane by

hydrogenation using palladium catalyst. The affluent

from C2 hydrogenation is routed to green oil tower where

green oil is removed by washing with cold ethylene. The


50

overhead from green oil tower after passing through

secondary

dehydrator is fractioned in ethylene tower to separate

ethylene and ethane. Ethylene tower has 116 trays and

operates at a pressure of around 18 kg/cm2 abs to produce

ethylene product of 99.8% by mole. A part of the ethylene

(5%) is cooled and sent to cryogenic storage. From the

remaining 95% ethylene, cold is recovered before sending

it to downstream plant. The ethylene tower bottom supplies

the ethane recycled to the cracking furnace.

PROPYLENE RECOVERY:

The bottom of the deethaniser is sent to depropaniser,

which operates at 7.2 kg/cm2. In depropaniser, propane

and propylene are recovered in mixture form. The

propane/propylene mixture from the top of the

depropaniser is fed to C3 hydrogenation system where

methyl acetylene propadiene is converted to

propane/propylene. The reaction takes place at temp 9-44 C

and pressure of 16.4-17.4 kg/cm2 in C3 hydrogenation

system. The propane/propylene mixture is then fractioned

in propylene tower to give chemical grade propylene as top

product and propane as bottom product. Propylene tower is

maintained at a pressure of around 18 kg/cm2 and has

109 trays. The propane is recycled back to furnace.

BUTANE RECOVERY:

The bottom product from depropaniser is routed to

debutaniser, which operates at 4 kg/cm2. The overhead


51

product is C4 fractions and bottom product contains C5

and heavier materials, which is sent to battery limit.

REFRIGERATION:

The plant has a 4-stage propylene refrigeration and 4-

stage ethylene refrigeration. Propylene refrigerant

compressor is designed to supply propylene refrigerant at -

38.9 C, -24.4 C, -5.6 C and 7.2 C. The compressor is driven

by condensing steam turbine. Ethylene refrigerant

compressor is designed to supply ethylene refrigerant at

four levels 100.6 C, -84.4 C, -67.8 C and -48.3 C respectively.

The compressor is driven by a condensing steam turbine.

PROPYLENE REFRIGERATION SYSTEM

The Propylene refrigeration system will be put in normal

operation as the first one of the three main compressors.

C3R system will be utilized for cool down of the

Demethanizer and it will be the single source of process

refrigeration until C2R system start up. Propylene

refrigeration system provides the initial chilling of gases

down to –38.90

C. Propylene refrigerant at different pressure

pickup the heat from other streams generating propylene

vapors at different pressures. Propylene refrigeration

compressor compresses these vapors with discharge pressure

of 17.5 kg/cm2, at which the propylene is condensed using

cooling water. The liquid propylene is then flashed back,

to provide chilling down to –39.2 0

C in the circuit.

REFRIGERATION SYSTEM IN GCU


52

To get the desired products and by products of required

purities from furnace effluents, it is required to be passed

through a series of distillation columns after cracked gas

is compressed and chilled adequately. The chilling is

achieved by refrigeration system.

Refrigeration system in GCU consists of Propylene

refrigeration system (C3R) and Ethylene refrigeration

system (C2R). C3R compressor is driven by backpressure

cum condensing type turbine running using 105 kg/cm2g

steam. C2R compressor is driven by condensing type

turbine using 40 kg/cm2g steam.

Four modes of operation for each of the refrigeration

compressors were studied by the licensor SWEC. There are 2

different feed cases, referred to as Case 1 and Case2.There

are 2 different chilled liquid ethylene product rates

referred to as Case A and Case B. These two chilled liquid

ethylene product rates are 24000TPA and 155000TPA

respectively.


53

LPG UNIT

The objective of this unit is to recover Liquefied Petroleum

Gas (LPG) and propane from Natural Gas (NG) and to

provide C2/C3 feed stock to the existing Gas Cracker Unit

(GCU).

PROCESS DESCRIPTION:

Feed from GPU is fed at the 6th

tray of C2/C3 column having

36 valve trays. Column is operated at a pressure of 22

kg/cm2. The column is designed to operate at a temp of 7.7

C at the top and 82.3 C at the bottom. Column top product

is mainly C2, C3 and some percentage of C4 at a temp of -3

C which is transferred to C2/C3 storage or GCU by C2/C3

reflux and transfer pump and bottom product is C3+ which

goes into LPG column for further fractionation. Top

product C2/C3 vapor from C2/C3 column is condensed in

the condenser by propylene refrigerant.

LPG COLUMN:

Bottom product C3+ from C2/C3 column is fed at 14th

tray

of LPG column having 54 valve trays. Column is operated

at temp of 150 C and 15.5 kg/cm2. Temp at the top and

bottom of column are 58 C and 130 C respectively.

Operating pressure is 11 kg/cm2. Top product of the

column is LPG vapor (C3, C4 and some C5), which goes into

condenser where it is condensed by cooling water, which is

being circulated in tubes. LPG product at 45 C is pumped

to the LPG storage bullets by reflux and transfer pumps.

Heat load is provided by MP steam at 16 kg/cm2. Now,

bottom product goes into pentane column.


54

PENTANE COLUMN:

In pentane column, pentane and Spatial Boiling Point

Solvent (SBPS) are recovered. Feed enters at 15th

tray of

column having 19 valve trays. Column is designed for a

temp of 85 C and a pressure of 16.8 kg/cm2. It is normally

operated at a temp of 42 C at the top and 66 C at bottom

and a pressure of 14.2 kg/cm2. Top product of column is

pentane vapor which goes into condenser where it is

condensed by cooling water and then it is stored in the

storage tank and part of condensed pentane is used as

reflux in the column. Bottom product is SBPS, which is like

petrol. Head load is provided by LP steam at 5 kg/cm2.

PROPYLENE REFRIGERATION SYSTEM:

PRS has been provided in order to take care of chilling in

LPG unit. Turbine, which is driven by VHP steam, produces

MP steam & LP steam. MP steam is used in LPG bottom

reboiler and LP steam is used in bottom reboiler of C2/C3

and of propane column. Mechanical work produced in this

process is used to run compressor. Propylene liquid is used

as cooling medium in C2/C3 over head condenser to

condense the C2/C3 vapor. Propylene gets vaporized

during the condensation process. Propylene vapor is fed to

the Knock Out Drum (KOD-3). From KOD-3, it is fed to the

suction of compressor at 4.8 kg/cm2 and -7.0 C and

remaining propylene liquid is pumped into evaporator

where it is converted into vapor and then transferred to

KOD-2 and some liquid which is not vaporized goes into

evaporator where it is converted into vapor and this vapor

is fed to KOD-1. Vapor from KOD-1 at 1.4 kg/cm2 and -41 C


55

is feed for suction-1 and it comes out from discharge-1

and D-1 goes into S-2 along with feed at 2.3 kg/cm2 and -

28 C coming from KOD-2. This compressed feed comes from

D-2 and goes into S-3 along with the feed from KOD-3.

Now this compressed vapor coming out from D-3 is routed

to S-4 along with vapor at 8.7 kg/cm2 and 13 C from KOD-

4. Final discharge from compressor is routed to condenser

where propylene vapor is condensed by cooling water and

then it is fed into accumulator at 40 C and 16.9 kg/cm2.

From accumulator, it is routed to KOD-4 and then it is

sent back to the C2/C3 condenser. Make up refrigerant is

also provided because of loss in propylene during

operation. Antisurge valves are provided to each KOD to

avoid back flow.


56

GAIL is the only HDPE/LLDPE plant operating in Northern

India and has a dominant market share in North India.

The primary thrust markets for the polymers had been

Western India, but, with the entry of GAIL in the HDPE &

LLDPE market Verticals, today North India has also

witnessed a rapid and significant growth in the polymer

downstream processing Verticals. In a successful span of

about a decades of establishing and marketing its grades

under the brand names G-Lex & G-Lene, GAIL has along

side augmented its name plate capacity of HDPE & LLDPE

to 4,10,000 MTPA by adding another dedicated HDPE

downstream polymerization unit of 1,00,000 MTPA.

GAIL has two trains of dedicated HDPE units of the Mitsui

slurry technology license (capacity 2 x 1,00,000 MT/A) and

marketing the grades under the brand name of G-lex and

one train of the HDPE/LLDPE swing plant under the

Novacor solution based technology license (capacity

2,10,000 MT/A).

Further by adding 6th furnace & de-bottlenecking of the

plant, the GAIL‟s Pata plant capacity will reach to 5,00,000

MTs of Ethylene & 5,00,000 MTs of HDPE/LLDPE producing

capacity by FY 2011-12.

The petrochemicals business of GAIL has consistently

achieving all set targets with respect to its production and


57

sales all through-out.

GAIL has also formed a Joint venture company by the

name of M/s Bhramaputra Cracker and Petrochemicals

Ltd. (BCPL) to accelerate the GoI‟s only authorized

petrochemical project in the North East of India (at

Lepetkata, Assam, India). The BCPL is a JV between the

Government of Assam, GAIL(I) Ltd., OIL (India) Ltd. &

NRL.

Further, GAIL has plans to augment the installed capacity

further by putting up new plants of HDPE/LLDPE by 500 KTA

at Pata, which is targeted to be operational by FY 2013-14.

References :

Contents from the library of GAIL(India) Ltd. Pata

www.wikipedia.org/wiki/GAIL

www.gail.nic.in

GAIL summer training report......

Technology

gail gas limited

gail summer training

gail employees

mmscmd of natural gas

gas exploration blocks

major gas fields

compressed natural gas

natural gas value chain