Internship Report Ibrahim Fibres Limited

7/23/2019 Internship Report Ibrahim Fibres Limited

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Internship Report

Ibrahim Fibers Limited

BY

MUHAMMAD SHAFIQUE

SYED IMMAD HUSSAIN SHAH

MUHAMMAD AFTAB AALAM

HAMMAS SALEEM

GIK Institute

Ibrahim Fibers Limited, 38/40 Km FSD-SKP Road, Faisalabad

August 11, 2014


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Internship Report| 2014

1

ACKNOWLEDGEMENT

Firstly, we would like to thank Almighty ALLAHwho is the creator and master of this

universe and everything in it. After that we would like thank IBRAHIM FIBRES ltd. for this

learning and developmental opportunity in our career.

We are thankful to Mr. Muhammad Tahirfor guidance and supervision in spinning &

fiber line. A thanks to Mr. Shahbazand Mr. Rashid Ghafoorfor helping in their department.

We are also grateful to Mr. Irfan Mirzafor watching over us in polymer and utility. We would

also like to thank Mr. Usman, Mr. Ghulam Murtaza and Mr. Salman for helping us in

polymer and utility. We are thankful to Mr. Nadeem Aslam for teaching us everything he

could in PG-1. Mr. Naeem, Mr. Umairand Mr. Sakhawatalso helped us learn a great deal

in PG-1. We are also grateful to the co-operative and helpful staff of IFL that helped us in our

learning.


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PREFACE

In this report we have comprehended every process and technique used in the departments

we visited during our four weeks internship at IFL. Weve divided this report into four parts.

In First part we have given information regarding the history and setup of IBRAHIM GROUP

OF COMPANIES. In the second part we have discussed utilities. Third part deals with the

Polymer and draw lines and their maintenance. The last part concerns us with the Power

Generation Department and its maintenance.


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LIST OF CONTENTS

ACKNOWLEDGEMENT.................................................................................................................... 1

PREFACE.............................................................................................................................................. 2

INTRODUCTION................................................................................................................................. 5

IBRAHIM FIBERS LIMITED............................................................................................................ 6

IFL (PP) -1 .......................................................................................................................................... 6

IFL (PP) -2 .......................................................................................................................................... 7

IFL (PP) -3 .......................................................................................................................................... 7

Textile plants ....................................................................................................................................... 7

PG -1 (power generation plant):.......................................................................................................... 7

Orientation plan................................................................................................................................... 8UTILITY (UTY).................................................................................................................................... 9

PTA & MEG Handling Unit ............................................................................................................... 9

Chiller ............................................................................................................................................... 11

Water Treatment plant ...................................................................................................................... 13

Boiler ................................................................................................................................................ 13

Cooling Tower .................................................................................................................................. 15

HTM Heater ...................................................................................................................................... 15

Gas Turbine ....................................................................................................................................... 16

POLYMER.................................................................................................................................. 17

Paste Tank ......................................................................................................................................... 18

Screw Pump ...................................................................................................................................... 18

ES-I reactor ....................................................................................................................................... 18

ES-II reactor ...................................................................................................................................... 18

Process Column ................................................................................................................................ 19

PP-I ....19

PP-II .................................................................................................................................................. 19

Scraper Condenser ............................................................................................................................ 20

Pre-polymer Filter ............................................................................................................................. 20

PDR. .................................................................................................................................................. 20

Product Filter .................................................................................................................................... 20

SPINNING AND DRAW LINE................................................................................................... 21

Spinning Unit:................................................................................................................................... 21

What is Spinning: .............................................................................................................................. 21

Polymer Melt Flow: .......................................................................................................................... 22

Spin Pumps: ...................................................................................................................................... 23


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Spin Pack: ......................................................................................................................................... 24

Ring Oiler: ........................................................................................................................................ 24

Sunflower Wheel: ............................................................................................................................. 24

Draw Line/ Fiber Line:................................................................................................................ 25

Crimping Mechanism: ...................................................................................................................... 27

Cutting Operation: ............................................................................................................................ 28

Bailer:... ............................................................................................................................................. 29

A/C system: ....................................................................................................................................... 29

Maintenance Work in Spinning and Draw Line: .............................................................................. 29

MECHANICAL WORKSHOP................................................................................................... 31

Machining Shop: ............................................................................................................................... 31

Insulation, Cladding & Ducting: ....................................................................................................... 33

Welding: ............................................................................................................................................ 33

Rigging Shop: ................................................................................................................................... 34

Painting Shop: ................................................................................................................................... 34

Carpenter Shop: ................................................................................................................................ 35

POWER GENERATION I (PG - I)............................................................................................. 36

Diesel Engine Cycle: ......................................................................................................................... 36

Engine Operation Processes: ............................................................................................................. 37

Engine Specifications: ...................................................................................................................... 37

Cooling Towers:................................................................................................................................ 37

HRSG (Heat Recovery Steam Generator): ....................................................................................... 38

Maintenance Work at PG1 Plant: .................................................................................................. 38

500 hours ........................................................................................................................................... 38

1000 hours ......................................................................................................................................... 38

2500 hours ......................................................................................................................................... 38

Major Overhauling (MOH) ............................................................................................................... 39

INTERNSHIP ASSIGNMENTS.................................................................................................. 39

Vibration Analysis of Draw Frame II Machine..40

Determining Torque in the roller of Draw Frame II Machine...54

CONCLUSION56


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INTRODUCTION:

The group started with a cloth trading business in the industrial city of Faisalabad. Late

Haji Sheikh Mohammad Ibrahim, founder of the Ibrahim Group. What is known in business

today as Ibrahim Group with diversified business interests from Spinning to PSF, Financial

Institutions to Banking and Energy, started off as a mere cloth trading agency just half a century

ago.

In the mid 50s the group was taken over by Sheikh Mukhtar Ahmad, It was then that he

took an initiative of adding yarn trading in the business that set a milestone for the future

progress. it did not take long before the group was widely reputed and respected in marketing

of cotton and blended yarns. Backed by this good will and experience in marketing, in 1980,

manufacturing of own blended yarn was initiated by establishment of Ibrahim Textile Mills

Limited. With long term considerations and a simple principle of no compromise on quality

two more textile spinning companies; A.A. Textiles Limited in 1982 and Zainab Textile Mills

Limited in 1987 were established. A power generation Company Ibrahim Energy Limited was

incorporated in 1991 to improve the efficiency of the existing manufacturing companies. All

these manufacturing companies have now been merged into Ibrahim Fibers Limited.

The Group established a leasing company; Ibrahim Leasing Limited. Upon declaration of

the privatization policy by Government of Pakistan, Ibrahim Group together with other leading

groups participated in the bidding to acquire controlling shares of Muslim Commercial Bank

Limited. Under the scheme of reconstruction proposed by State Bank of Pakistan, Consortium

of Ibrahim Leasing Limited, Ibrahim Group and its sponsors acquired more than 75% of the

shareholding of Allied Bank of Pakistan Limited. Management and control of the Bank was

handed over to Ibrahim Group on August 19, 2004. At present Ibrahim Group is holding more

than 80% shareholding of this bank. One of the top five banks of Pakistan, Allied Bank has

more than 742 branches across the country with 7,139 employees and financial assets of Pak

Rupees 234 billion. After the acquisition of the bank Ibrahim Leasing Limited has been merged

into Allied Bank limited. The strength of the group today stands manifold with entrepreneurial

skills and visionary leadership of Sheikh Mukhtar Ahmed added with fresh concepts and

professional skills of Mohammad Naeem Mukhtar who has done his MBA from the University

of Wales, Cardiff, UK. and Mohammad Waseem Mukhtar who has done his Bachelor in


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Computer Science and Masters in Total Quality Management (TQM) from the University of

Glam organ, Wales, UK .

Departments

Different Departments work and cooperate with each other to run Ibrahim fibers limited

smoothly and efficiently:

HR/Admin

Production(process)

Engineering-maintenance

Purchase departments

Imports departments

IT

Civil

Finance

Sales and marketing

IBRAHIM FIBERS LIMITED

Ibrahim fibers limited has three polyester plants, namely as:

1. IFL (PP)-1

2. IFL (PP)-2

3. IFL (PP)-3

1.IFL (PP) -1:

This plant start working in 1996, it is the first polyester plant in Ibrahim fibers limited.

The capacity of this plant is 193 tons/day. This was the first polyester plant of Ibrahim Fibers

Limited, when the stepped in the field of polyester manufacturing.


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2.IFL (PP) -2:

After the success of first polyester plant, Ibrahim Fibers limited decided to install second

polyester plant. This plant came into action in 2006, it is the second polyester plant in Ibrahim

fibers limited. The capacity of this plant is 410 tons/day.

3.IFL (PP) -3:

This plant start working in 2012, it is the third polyester plant in Ibrahim fibers limited.

The capacity of this plant is 650 tons/day.

Textile plants:

Spun Yarn Division of Ibrahim Fibers Limited consists of three projects;TP1 (Ibrahim

Textiles)TP2 (AA Textiles)TP3 (Zainab Textiles)All these projects were operating as

independent public limi ted companies and were l isted on stock exchanges in Pakistan

till September 2000 before their merger into Ibrahim Fibers Limited .

These projects are equipped with Real Time Ring Monitoring System (RTRMS), User

Ring Expert, Spin Vision, and Corner Pilot for online monitoring and analyzing to facilitate

production and efficiency while maintaining quality pa rameters. Moreo ver, auto-

doff ing system has been inst alled on the spinning and winding machines to automate

the manufacturing process. To maintain and to keep an edge we keep on adding latest

machinery and technical know-how.

PG -1 (power generation plant):

The need of energy in polyester plant and textile plant is mainly full filled by PG-1.The

full capacity of PG-1 is 58.3 MW. There are 11 engines in PG-1 with 5.3 MW capacity each.

All the engines are purchased by a Japanese company NIIGATA. There are three phase in PG

-1:

1. Phase I

2. Phase II

3. Phase III


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1.Phase I:

To meet the needs of energy, Ibrahim fibers Limited installed their first phase of PG-

I.There were 4 engines installed in 1993, each with 5.3 MW capacity.

2.Phase II:

With the passage of time, the need of energy increased .Then Ibrahim Fibers Limited

decided to install their second phase.2 more engines were installed in 1997, each with 5.3 MW

capacity.in 2006, six engines were shifted to bi-fuel.

3.Phase III:

Due to the energy crises in country, Ibrahim Fibers Limited decided to become self-

sufficient in the field of energy to run their plant efficiently. In 2012/13, 5 more engines were

installed in phase III, each with 5.3 MW capacity.

Orientation plan:

On the day of our first visit to Ibrahim Fibers Limited, the Human Resources department

made sure that not a single moment of our visit of Ibrahim Fibers Limited goes to waste. They

took us to different departments of the plant or asked the managers of some plants to give some

of their precious time to us so that we can have an idea that how the departments are working

together in huge setup like Ibrahim Fibers Limited.

Our internship was divided into four major departments;

HumanResources/Admin/ CA

Polymer&Utility

Maintenance

Spinning &Fiber Line

Maintenance

MechnicalWorkshop

PG 1-Maintenance


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UTILITY (UTY)

Utility is a general department of polyester plant which provides utilities required in process

of fiber manufacturing and plant operations. These utilities also provide operational capabilities

to other plants i.e. IFL PG-I etc. Its maintenance comes under the Polymer & Utilities

Maintenance department. The main utilities of polyester plant are:

Details of these utilities are as under:

1.PTA & MEG Handling Unit

Pure Terephthalic Acid (PTA) and Monoethylene Glycol (MEG) are the key ingredients to

make polyester fibre. These are the starting materials which react under specific conditions and

catalyst in polymer section to give molten polyester. Both of these reactants are handled

differently as described below:

PTA Handling Unit

PTA is brought in plant in the form of powder. It is in shipped in two form i.e. Bags and

container. Both have different charging method.

PTA & MEG Handling unit

Chiller

Water Treatment Plant

Boiler

Cooling Tower

HTM heating unit

Gas Turbine (PG-II)


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Containers are directly offloaded on the bin silos from where it is transferred to storage tank

with the help of compressed nitrogen gas. Nitrogen gas is used for transportation because it is

inert and would not react with PTA.

Charging of PTA through bags is done by the system in which hoist carries two bags at a time

and discharge them through the vibrating screens in order to remove the oversized or

agglomerated particles. It takes 5 to 7 min to charge one bag into the bin silo. Then from Bin

silo PTA powder is carried to storage tank with the help of compressed nitrogen gas

MEG Handling

MEG is shipped from Karachi in the form of liquid. Before shipment, a series of tests are

performed at Port Qasim IFL plant to check the quality of MEG i.e.

Container Bin SiloStorage

TankPTA

Conveyer

Compressed

Nitrogen

Fig.: PTA Container handling

Container Bin SiloStorage

Tank

PTA

Conveyer

Compressed

Nitrogen

HoistVibrating

Screen

Fig.: PTA Bags handling


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1. Dip test

2. Temperature Test

3. Density Test

4. Moisture content Test etc. (less than 1%)

5. Color test

It is brought to polyester plant in tanks where it is pumped to storage tank through filters with

the aid of centrifugal pump and flexible pipe. Each storage tank has a capacity of 2000 tons,

each is provided by breathing valve (which are provided to maintain pressure on stored MEG).

It can both intake and breathe out vapors according to requirement.

2.Chiller

Chillers are used in utility to provide cold water to the plant. This cold water is used in A/C

unit to provide cold air for air conditioning of plant and quenched air for the spinning process

requirement.

There are two types of chiller based on different refrigeration cycle, which are being used in

utility of polyester plant. These are described below:

Vapor Compression Cycle

The ideal thermodynamic cycle for refrigeration is Vapor Compression Cycle. It is the simple

refrigeration cycle that is composed of 4 ideal processes i.e.

a. Isentropic Compression

b. Constant pressure heat

rejection

c. Throttling (constant enthalpy

process)d. Constant pressure heat

addition

These processes are clearly describes

by the following schematic diagram

and T-S diagram:

Vapor compression cycle operated chiller of polyester plant have the cooling capacity of 1000

ton and have mainly 4 parts (Evaporator, Compressor, Condenser and expansion valve).

Fig.: Schematic and T-S diagram of Vapor compression cycle


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The evaporator is basically shell & tube heat exchanger in which the chilled water is on the

tube side & the refrigerant (R-134a) is on the shell side. The heat exchanger used here is a 1-2

pass heat exchanger. The WCC (chilled cooling water) stream from the process (11-12C)

enters the evaporator in the tubes & is discharged at a temperature of 6-7C. The boiling point

of refrigerant is -26C. It is present in the liquid form and when the water stream passes through

the evaporator tubes, the refrigerant gets heat from the water and evaporates.

Similarly condenser is also shell and tube type heat exchanger in which refrigerant is on tube

side and cooling water from cooling tower is on shell side. Cooling water came from cooling

tower at 34C and leave the condenser at about 39C.

For throttling purpose, an expansion device is used which is actually a perforated disc and

allow the coolant to expand from high pressure to low pressure with constant enthalpy. The

compressor of chiller is a 2 stage centrifugal type compressor. The power of compressor is 591

KW.

Vapor Absorption cycle

Thermodynamically, vapor absorption

cycle is similar to vapor compression

cycle. Instead of compressing a vaporbetween the evaporator and the condenser,

the refrigerant of an absorption system is

absorbed by a secondary substance, called

an absorbent, to form a liquid solution.

The liquid solution is thenpumped to the

higher pressure. This operation is clearly

seen in schematic diagram. Because the

average specific volume of the liquid

solution is much less than that of the

refrigerant vapor, significantly less work

is required.

The vapor absorption cycle based chiller of polyester plant have water as refrigerant and

Lithium Bromide as absorber. Its cooling capacity is 550 ton per unit.

Fig.: Schematic diagram of Vapor absorption cycle


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3.Water Treatment plant

In this plant the ground water is treated through physical & chemical processes to make it

useful in the processing. The water is pumped from the depth of 350 ft. Two pumps pump the

water to the top of the three multilayer filters, which have beds of sands, having three layers of

sand of decreasing particle size. These filters are used primarily to remove the suspended

particles from the raw water.

Then water is demineralized and passed through candle type filter which have certain mesh

size. This filter is also called Bag filter. Then water is pumped at high pressure to pass through

spiral filter of very low mesh size. It has membrane of cellulose which separate soft water from

hard water. After that water is sent to storage tank for final distribution.

4.Boiler

The boilers are used for the production of steam, which is then used on many types of

equipment in the plant. The basic consumption of steam is in the fiber draw line, heavy furnace

oil & polymerization section.

There are basically two types of boilers and both of these are used in utility section.

a. Fire tube boiler

b. Water tube boiler

Fire tube boiler:

The name fire tube is very descriptive. The fire, or hot flue gases from the burner, is channeled

through tubes that are surrounded by the fluid to be heated. The body of the boiler is the

Raw

Water

PumpSand

Filter

Demineri

lizer

Bag

Filter

Hihgpressure

pump

Membrane

type Filter

Storage

tank

Fig.: Water Treatment sequence


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pressure vessel and contains the fluid. In most cases this fluid is water that will be circulated

for heating purposes or converted to steam for process use. Every set of tubes that the flue gas

travels through, before it makes a turn, is considered a "pass". So a three-pass boiler will have

three sets of tubes with the stack outlet located on the rear of the boiler. Both natural gas and

diesel is used as fuel in this boiler.

After the completion of second pass, hot gasses are moved toward super heater where it convert

saturated steam coming from boiler to super-heated steam. In super heater hot gasses flow in

the tube sides while the steam is in shell side.

Water Tube Boiler

Water tube boiler is a shell and tube boiler in which water is in tube side while hot gasses are

in shell side. This type of boiler is used in utility which is actually a Heat Recovery Steam

Generator (HRSG). It is installed at the exhaust of Gas turbine. There is gate at the exhaust of

gas turbine which provide selection of hot gasses to use whether in boiler or waste it through

chimney. The exhaust gasses enter the boiler at the temperature of 490-520C. The cold water

came from deaerator tank with the help of pumps to the HRSG. It has heating capacity of 25

ton and provide super-heated steam at 25 bar pressure.

Fig.: 3-pass Fire Tube boiler with super heater


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5.Cooling Tower

Cooling tower is used to cool the process water. Cooling towers are designed on the basis of

wet bulb temperature. The cooling tower cools the water by direct contact of water to the air

so the water cannot be cooled below the wet bulb temperature of the area.

The cross flow cooling tower with induced draft fan is the one in which the fan is placed on

the top of the tower and air enters into the tower from side slits. So the induced draft cooling

tower is more efficient. In the utility 13 induced draft cooling towers with cross flow

arrangement are used.

The water from the process returns to the top of the tower at 39C where it is spread all over

on the tower through the distribution

nozzles onto the wood fills, where

the air coming through the louvers

cools the water to 34C due to heat

transfer. Wood fills are used to

increase the contact area of air and

water. In the utility 13 induced draft

cooling towers with cross flow

arrangement are used. The flow rate

of water in cooling tower is 775

m3/hr and it has cooling capacity of

9000 kW.

6.HTMHeater

HTM is Heat Transfer Media and it is used in polymer section for retaining polymer in molten

form. Cold HTM came from polymer section and heated at about 280-300C in HTM Heater

and pumped back to polymer.

HTM Heater is basically a heat exchanger in which hot gases from a burner moved down a

vertical tower. This tower have the force draft fan at the top which force the hot gases to move

down the tower. Tower contained the tubes of HTM thus it act as shell and tube type heat

exchanger. At the bottom there is a duct which connect tower to the stack. Hot gasses leave the

heater through this stack and pumps pump the HTM to polymer section.

Fig.: Induced Draft cooling tower with cross flow

arrangement


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7.Gas Turbine

Gas turbine is the main component of utility. This section of utility is also called PG-II. Gas

turbine operates on Bryton Cycle which is ideal thermodynamic cycle. Bryton cycle is

composed of four ideal processes:

a. Isentropic compression (Compressor)

b. Constant pressure heat addition (Combustion Chamber)

c. Isentropic expansion (Turbine)

d. Constant pressure heat rejection (Atmosphere)

These process are clearly explained by the schematic diagram and P-V diagram.

Gas turbine of IFL utility section has 14 stages of compressor with intercooling between the

stages to decrease the temperature of compressed air and increase the efficiency of gas turbine.

The combustion chamber is pilot type burner where natural gas at 25 bar pressure is used as

fuel. This compressed natural gas and compressed air mixed at the ratio of 1:16 (by mass) and

burned to give high pressure and high temperature gasses. These gases are expand on 3 stage

turbine. The turbine use the enthalpy of hot gasses in its reaction stages to extract useful work

out of it.

This gas turbine have 11197 rpm. A gear reducer is connected between turbine and generator

so that generator is rotated at 1500 rpm giving the power output of 15.3 MW. The hot gasses

leaved the turbine at about 490-520C and is used in HRSG as discussed above.

Fig.: Schematic and P-V diagram of Ideal Bryton cycle


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POLYMER

Polymer is the department of polyester plant where the molten polyester is produced by

chemical reactions. Polyester is produced by the chemical reaction of PTA and MEG under

specific conditions and in the presence of catalyst. These reactions took place in this

department.

The simple process flow of polymer department for making polyester by chemical reaction of

PTA and MEG is as follow:

PTA MEG

Paste

Tank

ScrewPump

ES-I ES-II

Process

Column

Water

Condenser

PP-IPP-II

Scraper Scraper

Condenser

Scraper

Gear

PumpPre-Polymer

FilterProduct

FilterGear

Pump

Jet

S stem

Star Valve

Oligomer

Pump

Fig.: Process flow of polymer plant


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The Details of all these equipment is given below:

Paste Tank

It is the tank were paste of liquid MEG and powder PTA is formed. PTA and MEG are brought

here from storage tanks in the molar ratio of 1:1.2. This tank is equipped with a agitator which

makes the viscous paste by blending the reactants.

Screw Pump

Screw pump is positive displacement pump which provide high pressure and low flow rate and

is used specifically where viscosity of fluid is very high. Since the viscosity of past is very high

so this pump is used to pumps it to ES-I tank.

ES-I reactor

Esterification is a process in which acid reacts with alcohol to form ester which are

basically monomers. ES-I is jacketed vessel, in jackets HTM (Dowtherm vapor heating

medium) circulates in the coils and heats the mixture. Pressure of ES-1 is maintained at 0.5

bar. At this pressure and temperature MEG reacts with PTA to form monomers. As a result

of Esterification H20 evaporates as boiling point of MEG and H20 are 197C and 100C

respectively. Here level of vessel is kept almost 60%. Almost 95% reaction is completed

here. NT is also injected t o ha ve l eve l indica tion o f r e a c t o r . Residence time i s 233

min and reaction temperature is 258C.

ES-II reactor

From ES-I, this mixture is taken to Esterification unit II (ES-II) by oligomer pump. Here

temperature is kept between 265-270C and at 0.15 bar. HTM is used for heating. Here

reaction is 99% completed. Similarly H20 and MEG produced as a result of esterification,

evaporates at these conditions. In the ES-II unit TDO is added to give color to paste

which is formed after the reaction. The color of the paste after reaction is bright or semi

Fig.: Screw Pump


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dull. It can be given four different shades which are super bright, bright, semi dull and dull.

Then this esterification product (monomers) is taken to the Poly condensation section.

Process Column

Process column is use to recover EG from esterification process. The vapors of MEG and water

are brought to process column through a valve. Height of column is 14 meter with 16 bubble

cap trays. Its reflux is cool water comes from reflux vessel (1729-VO 1). Different Resistance

temperature detectors (RTD) are installed along the height to monitor the temperature. Its

conditions are controlled from DCS in IFL. Bottom temperature of column is 180C. From its

bottom recovered EG is sent to paste vessel. Water vapors are collected at the top of column

and sent to water condenser which condense it with chilled water.

PP-I

The monomers from ES-II reactor are transferred to PP-I reactor by gravity, upstream pressure

and downstream vacuum. This reactor is Pre-Poly Reactors I and it there is no agitator in it. In

this reactor monomer are combined to form polymers. One MEG molecule is released

whenever two monomer molecules are joined, and the continuous removal of these MEG

molecules pushes the reaction in the forward direction. Vacuum in these reactors plays an

important role in this process and is created through glycol vapor jets. The recovered MEG is

reused as raw material. Heating in the whole polymer process is done by HTM (Santotherm

Oil) which is re-circulated after heating in special heaters.

The vacuum created here is based on the simple principle. If we remove vapors from an isolated

vessel, it will create vacuum behind. In PP-I, vacuum is created directly by vacuum pump. It

sucks the non-condensable vapors of EG from condenser, resulting the vacuum behind in the

system. In it vacuum pressure is 120 mbar.

PP-II

This is Pre-Polymer reactor II. The oligomers from PP-I are transferred to PP-II reactor under

gravity and downstream vacuum. In PP-II, the non-condensable vapors of EG from its

condenser are sucked. This results vacuum behind. Vacuum here is 20 mbar which is more fine

than PP-I. This reactor also have the continuous supply of HTM for heating the product.

This tank is equipped with Perforated Disk Reactor (PDR) which rotates in the vessel to

increase the exposed surface area of oligomer. This results in removal of MEG by joining of


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monomer molecule to form long chain monomers. As the length of the oligomer chain

increases, the movement of the molecules becomes sluggish, resulting in the increase in

intrinsic viscosity. Before the final reactor, the average intrinsic viscosity of the oligomer is

about 0.25

Scraper Condenser

Each PP-I and PP-II is attached with a condenser. The vapors of EG created in each reactor are

transferred in the respective condenser, where cold EG is showered from the top resulting the

condensation of vapors of EG. Vacuum is created and condensate from each condenser comes

downward through barometric leg in the immersion vessel.

Pre-polymer Filter

Product from PP-II is pumped by a gear pump through candle type filter. This filter have 130

candles with mesh size of 25 micron. It filter suspended particle in oligomer and allow pure

product to pass through it.

PDR

The final polymer reactor is called the DRR (Disc Ring Reactor). This is a huge vessel and has

a horizontally rotating shaft having a number of discs mounted throughout its length. The wholevessel is HTM heated and under approx. 1.0 mbar vacuum. Polymer flows into one end and is

picked up by the discs which increase its surface area exposed to the vacuum. Due to this, the

chain length of the polymer molecule grows up, which is required by the Spinning Process.

There is also a scraper condenser attached with DRR to condense EG vapors followed by a jet

system which is used for further condensation of EG vapors.

Product Filter

The polymer melt from the DRR is pumped by gear pump through a final polymer filter. It is

also candle type filter having 61 candles with the mesh size of 15 micron. It allows only filtered

and high quality product to move in spinning line.

A star valve is connected at the end of polymer section which provide supply of polymer melt

to spinning line. Special jacketed piping is used throughout the process with liquid HTM

circulating through the jacket keeping the polymer in molten form.


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SPINNING AND DRAW LINE

After 9 days at the Polymer and Utility department, the next one was Spinning and Draw Line

as per the internship schedule. Spinning is another important phase in the manufacturing of the

Polyester Fibers before it is drawn in the fiber line/ draw line. 9 days were dedicated to this

department. During this time period, all the important processes and the maintenance of

different machines and equipment were studied as well as practically observed.

Spinning Unit:

The spinning unit comes after the polymer. It is spread on four floor building each one having

different auxiliaries and reactors. These floors are given the names according to their height

form the ground e.g. 7 meter floor, 13 meter etc. All these floors are connected by a complex

network of pipe lines. Also there is a network of Chilled water, Steam and cooling water that

is necessary during different processes in the spinning unit. Also there is A/C unit that provides

this chilled water and the air to maintain the environment comfortable.

The spinning units of all the three plants are almost the same except a little difference. The

main different is of capacity. Due to the higher capacity of the IFL 3, the associated A/C unit

is of higher capacity than that of IFL 2 and so on. The detailed processes in this unit and the

maintenance work of the associated machines are proved below:

What is Spinning:

Spinning can be defined as the extrusion of polymer melt or solution through aspinneret. The

spinneret is a perforated disk through which the polymer melt is forced to pass with the help of

pressure developed by the pumps. Three major typesof Spinning are:

i) Melt spinning : Starting polymer is heated to molten state

ii) Dry spinning : Starting polymer is in solution and solvent is separated by evaporation

iii) Wet spinning : Polymer is in solution but the solvent is non-volatile

Here at Ibrahim Fibres, Melt Spinning is used. The polymer melt coming from the poly

condensation plant, through a jacketed pipe system, passes through a polymer heat exchange

on its way to the spinning manifolds. The process line is heated with HTM liquid. The polymer

heat exchanger is used to heat or cool the polymer to the required spinning temperature. This

required temperature is adjusted with the help of a liquid HTM circulation system via a HTM

circulation pump, polymer heat exchangers and HTM air cooler.


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The processes involved in Melt Spinning are given as under:

1) Polymer Melt Flow:

There are 2, 3 and 4 lines in IFL 1, 2 and 3 respectively that come from the polymer unit. The

working of each of these lines in a plant are the same. Each line that is coming from the polymer

section i.e. polymer melt, gets divided into the 16 lines. This network is shown in the figure

below. Each of these 16 lines are further divided into 2. Thus at the output we get 32 lines from

one line of polymer melt. Each line has a spinneret at the end through which the polymer is

forced to pass.

The number of end lines and thus, spinneret slightly differ in IFL 1, 2 and 3. These temperature

of these lines is maintained to avoid the solidification of Polymer melt with the help of HTM.

Fig. :General Melt Spinning Process


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2) Spin Pumps:

The spin pumps are located at the upper side of the beam. Each spinning position has its

separate spin pump that feeds the polymer melt to the spin packs at a uniform metered flow

rate. All of these are Gear

Pumps because of the higher

viscosity of the polymer melt.

Gear pumps in IFL 1 has the

through put of 70 cc/ rev while

that of IFL 2, 3 have 100 cc/ rev

because of the higher capacity of this plant.

Polymer melt

Spinneret

Spin Pump

Spin Pump

Shaft

Fig.: Polymer melt flow in which one line is divided into 32 lines

Fig.: Gear Pump Functioning


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3) Spin Pack:

In spin pack polymer melt is converted to filaments. Each one of the 32 lines as shown above

has one spin pack. The polymer melt passes through this unit and is converted into filaments.

Each spin pack consists of sand filter at the top and then a fine filter. As the polymer passes

through these filters, undesirable particles are removed and a filtered polymer gets extruded

through the Spinneret. The spinneret is at the

bottom of the Spin Pack.

Spinneret consists of a meshed plate of

certain size and density. As the filtered

polymer melt passes through this spinneret,

filaments of certain size (corresponding to the

size of the mesh) are formed. Quenched air is

given to these filaments just after the

formation so that the filaments get solidified

suddenly.

4) Ring Oiler:

There is a ring oiler that provides spin finish oil (SFOil) to the filaments. Its purpose is toremove any kind of static charges on these filaments. SF oil is supplied with the help of pumps.

Each pump supplies spin finish oil to the two spinneret filaments.

5) Sunflower Wheel:

After the filaments are formed in 32 spin packs, they are combined into a single tow with the

help of a series of rollers. The tow formed is passed through sunflower wheels. The sunflower

wheel is like a spur gear that has a shape like sunflower. There are two such wheels that rotate

independently with the same rotational speed. The main purpose of the sunflower wheel is to

pull the tow down into the cans as well as to do a binding action on the filaments so that they

have strong binding in the tow.

Sunflower Wheel is the last part in the Spinning unit after which the tow formed is dumped

into the cans. The cans filled are then taken to the draw line unit where the next phase of the

polymer manufacturing starts. The tow formed from each line in the IFL plant is continuously

dumped into the cans. These cans are taken to the draw line with the help of Fork Lifters.

Polymer Melt in

Sand Filter

Fig. Spin Pack

Polymer

Filaments

Fine Filter


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Draw Line/ Fiber Line:

In this unit the tow filled in cans from the spinning unit is drawn. This is the most critical

process as different parameters in this unit affect the fibers properties and thus its quality

directly. The tow form different cans is drawn off and is drawn with the help of a series of

rollers accompanied by the other necessary processes. In all the three plants, drawing process

is the same except a little difference in the machines. The processes involved in Fiber line are

shown in the figure line with Y symbol showing tag assigned to each machine.

Each of these processes are detailed as under:

1. Can Draw off Creel Y01:

Here the sub-tows/ bands from cans are drawn off with the help of small rolling creels above

cans.

2. Tow Formation Unit Y02:

Here the sub tows coming from the cans are arranged in three bands.

3. Guiding Unit Y03:

This unit consists of 7 rollers which guides the 3 bands of the tow formed above.

Can Draw

Off Creel

Y01

Tow

FormationUnit

Y02

Guiding

Unit

Y03

Dipping

Bath

Y04

Draw

Frame I

Y05

Draw

Bath

Y06

Draw

Frame II

Y07

Heating

Channel

Y08

Draw

Frame III

Y09

Thermose

tting Unit

Y10

Tow

CoolerY11

Draw

Frame IVY12

Convergant

unitY13

3 Roller

FrameY14

CrimperTension

ControlUnit

Y15

Pre-

HeatingChamber

Y16

Crimper

MachineY17/18

Traversing

UnitY19

Spin FinishApplication

Unit

Y20

Drawing

UnitY21

Fig.Machines and Processes in Draw Line


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4. Dipping Bath Y04:

Here spin finish oil bath is given to the tows at a temperature of 20-22C to Pre-lubricate the

tow and maintain the temperature of all the tows coming to a constant level. It also helps to

stick the sub-tows in the bands.

5. Draw Frame I Y05:

The draw frame is used for the drawing of the polymer along its length. It has 7 rollers, in

which first roller is also attached to a nip roller to drip off spin finish oil from the dipping bath.

The treatment of the tow starts here.

6. Draw Bath Y06:

This is a closed tank where the spin finish oil at 75C is showered on the tow. The steam in the

plate type heat exchanger heats the spin finish oil.

7. Draw Frame I Y07:

This is the second draw frame present in the fiber line. It has 7 rollers which are heated with

the help of hot water. It also has a nip roller at the start.

8. Heating Channel Y08:

Live steam is injected and the temperature of the tow is raised to 180C.

9. Draw Frame III Y09:

Heated tow is now draw between Draw frame 2 & 3. Draw frame 3 rollers move with greater

speed & forced drawing occurs. Draw frame 3 has the maximum load.

10. Thermosetting Unit Y10:

In this chamber the properties achieved by the tow are stabilized.

11. Tow Cooler Y11:

The tow from the thermosetting unit is passed through the cooler where spin finish oil is

sprinkled by 12 nozzles. The tow is cooled to 90-100oC.

12. Draw Frame IV Y12:

This unit consists of seven rollers. It also has a nip roller at the start. At the end of Draw frame

IV the tow are separated again into three bands one above the other.


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13. Convergent Unit Y13:

This unit overlaps the three tows used in the drawing & forms a single tow whose width is

comparable to the width of the crimper intake.

14. 3 Roller Frame Y14:

As the name indicates, this unit also has three roller and a nip roller as well.

15. Crimper Tension Control Unit Y15:

This unit controls the tension of the tow before the crimper machine. The speed of this roller

and that of crimper machine are interlocked in such a way that the tension of the tow remains

within the certain range.

16. Pre Heating Chamber Y16:

The tow is heated before it enters to the crimper machine.

17. Crimper Machine Y17/ 18:

There are two crimper machines: one on standby while the other running. This machine is the

most important in the process of the draw line as it forms crimpers on the tow that gives the

fiber properties like cotton.

Crimping Mechanism:

Crimper machine mechanism is shown in the figure below:

Tow into the

crimper

machine

Upwards force due to the

pressure developed by the

tow sandwiched between

the plates

Stuffer Box

Plate

Crimpers formed due

to the squeezing of tow

between plates and

thus pressure between

the plates is increasing

Fig.Crimper Machine Mechanism

Fixed Plate

Roller


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The tow coming from the tension roller enters into the crimper machine through rollers. This

machine consists of two plates- one at the top called Stuffer Box Plate and the other at the

bottom that is fixed. The upper plate is give a downwards force by the pressure applied to it

through hydraulic cylinders. As the tow enters in between these two plates, it gets squeezed

and the outlet remains closed as long as the pressure developed by the accumulation of the tows

remains less than that of applied to the upper plate. Once this pressure is achieved, the upper

plate moves up giving a way to the crimped tow to exit the machine from behind. This process

continues and the tow entering the machine is crimped and then it moves forward leaving the

machine.

18. Traversing Unit Y19:

The tow leaves via traversing unit which spreads it on the drying plate because of its

continuous sideways motion.

19. Spin Finish Application Unit Y20:

At the end of the traversing unit, spin finish oil is sprinkled over the crimped tow with the help

of a nozzle to reduce its temperature that was increased before crimping.

20. Drying Unit Y21:

In this section the tow is dried & cooled. This section consists of four zones, one of which is

cooling zone while other is heating zone. 10-bar steam is supplied for the heating zone. After

being dried the tow is transported to the cutter vertically to free roller. In this unit the tow

continuously move forward because of the perforated base motion using roller-chain system.

21. Cutting Operation:

The tow is raised at the top towards the cutter. The cutter consists of a circular plate and circular

blade. The tow is wrapped around the cutter plate and when circular plate touches the cutter

then the fiber in specific length is cut down. In order to get different cut lengths, certain number

of blades are used that are given as under:

Cut Lengths (mm) Number of Blades

32 88

38 75

44 64

51 5864 44

Table:Different cutters used to get certain cut lengths


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22. Bailer:

The fiber after cutting comes to the prebin chamber attached to a weigher bin. When the weight

of the fiber reaches to 50 kg, a pusher comes and pushes it to the pressure area where the fiber

is pressed with a hydraulic system. When the weight of the fiber becomes 350 kg the fiber is

rotated to the main press where hydraulic system is used to press it and form a bail.

The bails formed are transported continuously from the bailer unit with the help of fork lifers

that carry these bails to the storing place.

A/C system:

The Quench AC process consists of recovering air from the system, filtering it, washing and

humidifying it, cooling it, re-pressurizing it and finally filtering it again before supplying it to

the end users. Unlike regular air-conditioning systems, which provide cool and dry air to keep

the area cool, this is a special type of air-conditioning.

In this process, the air is not only cooled to a certain temperature, it is also humidified to 85%

relative humidity. This is achieved by passing filtered air through a washing process where soft

water is sprayed into it using special nozzles. After this, it is passed through chilled water

cooled coils that decrease the air temperature to the desired set-point. Here, some of the

moisture absorbed by the air in the washing process, is condensed, the resulting cold and

humidified air is passed into the quenching ducts after a final fine filtration.

The quench-air (1920oC) A.C station comprises a critical part of the spinning plant. Its main

purpose is to provide conditioned and controlled quantity of air for quenching the hot extruded

filaments. For each of the three spinning lines, there is an individual quench-air system,

independent of each other.

Maintenance Work in Spinning and Draw Line:

Almost all types of maintenance work is done in this unit i.e. Preventive Maintenance,

Predictive Maintenance and Shut down Maintenance. In addition to the daily maintenance

activity i.e. (Preventive maintenance), all the machines working are also checked time to time

by testing their vibrations, sound, output etc. If any unusual fault is noticed, it is eliminated so

that the smooth operation of the plant is assured.


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During our stay in this department we observed certain maintenance activities that are given as

under:

Maintenance of the Draw Frame machines is done very often. It involves changing of

the front as well as rear Bearings. Also, the lubrication to the machine is maintained

by inspecting it on regular basis. The bearing changing process is important. It is done

by following steps as provided in the catalogue. The vibration measurement of the

machine is another important task. During our stay we worked on the vibration analysis

of the draw frame II machine which is detailed in the coming section.

Similarly the temperature of the steam, pressure of the lubricating oil, pressure of the

steam as well as hydraulic pressure in the crimper machine in Fiber line are some

important parameters that are continuously monitored.

Roller in the crimper unit are machined after certain period of time if there is some

unusual pattern of the crimped tow.

An important maintenance work in the polymer unit is of the Spinneret. The mesh size

in the spinneret is important. Also the sand filtersin the spin pack are changed.

The sealing of the gear pumps used are also checked regularly.

In A/C unit, there are a number of filters used. These filter are also replaced or cleaned

if the differential pressure across them is out of range.

The continuous supply of the quenched air is also ensured.

In the bailer machine, the seals of pumps are most often damaged because of the

continuous operation of this machine. Thus it seals are changed regularly.

After each 650 tons cutting, each blade is inspected and replaced if needed.

Apart from some above mentioned maintenance activities, there is also major maintenance

work that is done by shutting down the whole plant. The IFL II plant was shut during our whole

internship period because of some maintenance work. All these maintenance work is done to

ensure the smooth running of the plant as well as to get the highest possible level of quality in

polyester.


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MECHANICAL WORKSHOP

The workshop of IFL is almost entirely responsible for preventive as well as predictive

maintenance of entire group. Its the department that has kept the group up and running after

all these years, and they are doing a great job.

It has 5 departments which perform their respective jobs and are the best at what they do:

Machining Shop

Insulation, cladding &ducting

Welding

Rigging Shop

Painting shop

Carpenter shop

1.Machining Shop:

In this part of workshop different machine parts are repaired according to requirement

using different machines like milling machineand lathe machine:

Milling machine:

This machine is used to for profiling and fabricating spur gears. Milling is a cutting process

that uses a milling cutter to remove material from the surface of a work piece. The milling

cutter is a rotary cutting tool, often with multiple cutting points. In its operations the work piece

is fixed and the tool moves about its axis and removes unwanted material.

Fig. :Horizontal milling machine


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There is two types of milling process in workshop:

Face milling:Face milling is used to cut flat surfaces (faces) into the work piece, or

to cut flat-bottomed cavities.

Peripheral milling: Peripheral milling is well suited to the cutting of deep

slots, threads, and gear teeth.

Lathe machine:

This machine is used to perform various functions such as cutting, sanding, knurling,

drilling, or deformation, facing, turning, with tools that are applied to the work piece to create

an object which has symmetry about an axis of rotation such as shafts etc.

Lathe is a machine tool which rotates the work piece on its axis to perform various

operations and create an object which is symmetric about its axis of rotation. While in process

the work piece is fixed between the headstock and the tail-stock, it is said to be "between

centers", in this position it is much safer to work with the object at right angles to the axis.

When a work piece is fixed only to the spindle at the headstock end, the work is said to be

"face work".When a work piece is supported in this manner, less force may be applied to the

work piece, via tools, at a right angle to the axis of rotation, unless the work piece will rip free.

Fig. :Lathe machine


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2.Insulation, Cladding & Ducting:

This part of workshop is responsible for the installation and maintenance of all the

insulation of all the piping systems in process, HVAC and heating systems. All the insulations

are covered by aluminum cladding for protection and prevention from leaking.

This department is important because certain chemicals and steam rush through the

pipes at very high temperatures and their temperature needs to be maintained for smooth

running of the process. This department also fabricates ducts for the transportation of chilled

air in offices and throughout the plant, without which the temperature inside the plant would

be unbearable.

3.Welding:

Welding is a fabrication process that joins two metals or thermoplastics by coalescence.

This is often done by melting the work pieces and adding a filler material to form a pool of

molten material called the weld poolthat cools to become a strong joint. Sometimes pressure

is used in combination with heat, or sometimes the pressure alone to produce the weld.

Welding is different from soldering and brazing, which involves melting a lower-

melting-point material between the work pieces to form a bond between them, without melting

the work pieces, but in welding work pieces are fused together to form a joint.

There are two basic types of welding:

Arc welding:

It is a fusion type welding in which the weld is produced by the heat of an electric arc and

metal work piece. It is done by different methods such as:

Shielded metal arc welding (SMAW)

Gas tungsten arc welding (GTAW)

Gas tungsten arc welding (GTAW)

Flux-cored arc welding (FCAW)

Submerged arc welding (SAW)

Electro slag welding (ESW)


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Gas welding:

In this type of welding the welding flame is produced by a combination of gases

usually acetylene and oxygen.

There are different types of gas welding:

Metal Inert Gas (MIG)

Tungsten Inert Gas (TIG)

`

4.Rigging Shop:

This part of the work shop is responsible for all the heavy lifting and transportation

of finished product from one part to another. It can be called muscle of the plant. All the loading

and unloading of the products is managed by this part.

Rigging shop has lifters of varying lifting capacities, from 2 ton to 4 ton, for

transporting the tow containers to draw line and finished product (yarn) to the warehouse and

loading that in the trucks.

5.Painting Shop:

This part of the workshop keeps the looks of plant. It also paints all the machinery

to prevent it from corrosion. Since plant site faces a lot of vapors and fumes so if not protected

properly and regularly the life of machinery and building will reduce due to corrosive wear and

tear.

Fig. :Shielded metal arc welding


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6.Carpenter Shop:

All the furniture and wood work of the plant is produced by this shop. It fulfills

the need of every wooden accessory of the plant. It also repairs faulty furniture. Ladders in the

cooling towers are also made by this shop.

All these departments make Ibrahim Fibres ltd almost self-sufficient in maintenance and

upkeep of the plant.


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POWER GENERATION I (PG - I)

Last 7 days of our internship were spent in Power Generation- I. Power in this unit is generated

by the engines operating on furnace oil. If the gas is available, both of these fuels are used at a

time in order to get more economical power. However, all of these engines are manufactured

recommending diesel to be used as a fuel. The plant specifications are listed as under:

Phase-1 (HFO 4 Engines Niigata 4* 5.3=21.3MW) installed in 1993

Phase-2 (HFO 2 Engines Niigata 2*5.3=10.6 MW) installed in 1997

Bi-fuel in 2006 of 6 Engines.

Phase-3 (HFO Engines Niigata 5*5.3=26.5MW) in 2012/13

Total Engines capacity=11*5.3=58.3MW

The total power generation of both GT and PG-1 add up to a total capacity of 58.3+15= 73.3

MW. All of these engines operate on Diesel Cycle.

Diesel Engine Cycle:

The diesel engine cycle is shown in the figure. A complete cycle has four processes:

Isentropic Compression

Heat addition at constant pressure

Isentropic Expansion

Constant volume heat removal

All the engines at the PGI are also have turbocharging. All the phase III engines have HRSG

system installed that used the exhaust heat to generate steam that is further used in the PP

plants.

Fig.Diesel Cycle


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Engine Operation Processes:

Engine Specifications:

Engine Model: Niigata 16V32CLX

Cylinder Bore =320 mm

Clearance volume = 10.1mm

Swept Volume =463 L

Compression ratio = 13.6

Air fuel ratio = 1:31

Maximum Power = 5.3 MW

Engine rpms = 600

Turbocharged

Cooling Towers:

The principle of cooling tower have already been described in polymer section. There are total

of 11 cooling towers. Phase 1 and 2 cooling towers are of induced draft fan type counter flow

cooling towers. The phase 3 engines cooling towers are of cross flow type.

Fig.Engine Operation Processes


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HRSG (Heat Recovery Steam Generator):

HRSG system is installed at the exhaust of the Phase 3 engines in which the energy at the

exhaust of the engines is utilized to convert water into steam that is used in Polyester Plant.

The technical specifications of HRSG are given as under:

Produces 2.8 ton/hr of saturated steam at 10bar and 191C.

Exhaust gas inlet temperature 345o C

Maintenance Work at PG 1 Plant:

PG-I have a huge mechanical system for power generation which required regular

maintenance for smooth operation. These engines are mostly used for providing power to thepolyester plat because it cannot afford any shut down. Thus schedule maintenance is very

necessary for the smooth operation of polyester plant. Maintenance of engines are planned

according to running hours of engines as described below:

500 hours

Following maintenance operation are performed at each 500 hour of running of engine since

last MOH.

Rocker arm nut and bolt torque is checked

Crank case and cam case is inspected

Crank case bolt tele-mark are checked

Tappet clearance are checked (0.5 mm clearance)

1000 hours

At each multiple of 1000 hour of running of engine since last MOH, following maintenance

operations are performed:

Primary and secondary filters of HFO are cleaned with air and oil

Crank case bolt tele marks are checked

Lubrication oil level are checked


2500 hours

At each multiple of 2500 hour of running of engine since last MOH, following maintenanceoperations are performed:


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Lapping of injectors nozzle is done

Lapping of exhaust valve seat is done

Rocker arm nut and bolt torque is checked

Crank case and cam case is inspected

Crank case bolt tele mark are checked


Major Overhauling (MOH)

After the each 8000 hours of running of engine, major overhauling engine is done which

include following maintenance:

Engine is opened completely

All inlet valves, exhaust valve and injection nozzles are cleaned

All the clearance of engine are observed

Cylinder head is lapped

Piston is taken out of engine and inspected

Lubrication oil is changed

All part of engine are inspected minutely and action are taken according to situation

***************************

INTERNSHIP ASSIGNMENTS

During internship we were given assignments in Fibre Line. Our group of four people was

divided into two sub- groups. These assignments were successfully completed and submitted

to the respective advisor. The group division and assignment given are listed as under:

Assignment No. 1 Vibration Analysis of Draw Frame ii Machine

Group Members

Muhammad Shafique

Syed Immad Hussain Shah

Assignment No. 2 Determining Torque on the Roller of Draw Frame ii

Group Members

Aftab Aalim

Hammas Saleem


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Vibration Analysis of Draw Frame II Machine:

The vibration measurements on the Draw Frame IImachine of the Fiber line in IFL I has shown

higher values at the end walls. These vibrations may cause the fatigue failure in the machine if

continued for the prolonged time. Find out the causes of these vibrations, give analysis and state

how these vibrations can be removed.

Solution:

The solution to this problem included the detailed study of the Draw Frame machine and measuring

the certain parameters that were necessary for vibration analysis. For that purpose, the natural

frequency and gear train specifications were obtained from the machine drawings. The detailed

solution of this problem involved certain steps that are given as under:

Vibration Data

The first step was to obtain the vibration data using vibrometer. This data was obtained after

identifying the critical points on the machine wall where maximum vibrations were observed. This

data was obtained in already measured form. This data at the tow outlet is presented as under:

Line Speed (m/min) Position No. 1* Position No. 2* Position No. 3* Position No. 4*

250 34 5 8 8

245 54 10 13 15

240 24 6 5 7

235 14 4.5 2.7 4.9

230 10 3.5 2.8 3.8

* In mm/sec

From the above data it is clear that the maximum vibrations occur at the position no. 1 at line speed

of 245.

Possible Reasons for Vibrations

Draw frame machine involves no damping with rotating parts that includes motor shaft,

intermediate shaft, meshing of gears with certain frequency and rotating rollers. The possible

reasons for the vibrations noted above might be:


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i) Rotating unbalance in any of the shafts because of the non-uniform distribution of the

mass or axial non-symmetry.

ii) Base excitation that involves the vibration of the machine because of the vibration of

the factory floor.

iii) Vibrations may be because of the resonance caused by the frequency of any rotating

part i.e. roller, gear meshing frequency, motor rotation or the rotation of intermediate

shaft. That rotating part will cause maximum vibrations whose frequency will be closer

to the natural frequency of the machine frame.

If we observe the vibration data, we see that the vibration value reaches to maximum at certain

line speed and then it again starts reducing. This type of behavior is a clear indication of the

resonance phenomenon. The shafts of the rotating rollers are well machined and thus have

precisely uniform mass distribution. Thus vibrations are not caused by rotating unbalance. Also

there are extremely small excitations of the base which cannot cause such vibrations as noted.

Thus the only reason that is causing these vibrations is Resonance. Some part among the rotating

ones in draw frame machine has rotational frequency that is much closer to the natural frequency

of the machine frame.

Resonance Analysis:

The resonance analysis involves the vibration response calculations at nominal line speed and for

the current line speed. For that purpose we have to calculate the rotating frequencies of each of

the rotating part i.e. Roller, Intermediate Shaft, and Driving Shaft. These calculations were

performed using gear train data and the speed of the line.

Gear Train of Draw Frame II machine:

Gear train analysis in required to calculate the speed of rotation of each of the shaft and teeth

meshing frequency so that it can be determined that which of these rotating component has thefrequency closest to the natural frequency which causes the maximum vibration. The rotation of

the roller is driven by the motor. This motor is attached to shaft which has a Gear A (as shown in

the diagram below). This gear drives intermediate shaft which again rotates the roller shaft due to

the gear meshing. Following diagram shows how the roller rotation occurs because of motor

through a gear train.


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i) At Nominal Line Speed:

First the analysis was done using nominal line speed of 180 m/min:

VL= 180 m/min = 3 m/s

The corresponding roller rotational frequency is given by:

r = VL / Rroller

where Rroller is the roller radius which is 205 mm

r = 3 / 0.205 = 14.63 rad / s = 14.63 2 . = 2.328 Hzr = 2.328 Hz

Teeth Frequency B = 2.328x 65

= 151.32 Hz

Teeth Frequency B = 151.32 Hz

No. of Teeth

Gear A .. 23

Gear B .. 27

Gear C .. 65

Gear D ...... 65

Nominal VL = 180 m/min

Current VL = 230 m/min


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Intermediate shaft rotation frequency = shaft= 65 / 27 x 14.63 = 35.22 rad / s

shaft=5. . = 5.605 Hz

shaft= 5.605 Hz

Teeth Frequency A = 5.605x 65

= 364.37 Hz

Teeth Frequency A = 364.37 Hz

Motor Rotational speed = motor = 65 / 23 x 35.22 = 99.534 rad / s = 950.487 rpm

motor =99.5

. = 15.84 Hz

motor= 15.84 Hz

The result of the above analysis has been summarized here:

Frequency* Value (Hz)

Roller 2.328

Intermediate shaft 5.605

Motor Rotation 15.84

Teeth Frequency B 151.4

Teeth Frequency A 364.37

* for nominal line speed

The natural frequency of the Draw Frame

II is 149.3 Hz as given in the FEM

Calculation report of FLEISSNER. We

see that the closest to the this frequency

is 151.4 Hz which is because of the teeth

frequency B. It means that the resonance

occurs because of the teeth meshing of

the gears B with C as indicated below at

nominal speed. This is indicated below in

the fig.

Resonance is caused by

meshing frequency of these

two gears which approaches

the natural frequency of thesystem


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ii) At Current Operating Line Speed:

The current line speed of the Draw Frame II is about 230 m / min. The same calculations are

performed for this line speed. The result is summarized directly in the table form as under:

*at line speed 230 m /min

The natural frequency of the system must not match or very near to any of these frequency

otherwise the resonance will occur and if prolonged for longer time, failure of the machine will

occur. From this data again we see that it is the teeth frequency B that is closer to the natural

frequency of the system i.e. 149.3 Hz. Thus in subsequent analysis the teeth frequency B will be

analyzed and the response of this driving frequency will be calculated at both nominal speed and

current line speed.

How to Minimize these Vibrations:

There are different ways to reduce vibrations in any system. However some practical approaches

that can be used to minimize these vibrations in Draw Frame II machine are discussed here:

i) Change the driving Frequency:

This is the simplest approach to reduce vibrations in any system. The meshing frequency of the

teeth that causes the frequency which is closer to the natural frequency of the system, is set in such

a way that its deviation from the systemsnatural frequency is increased. However, in changingthe driving frequency it should be noted that the new driving frequency must not be such that it

causes the frequency of the other rotating parts (e.g. of intermediate shaft) to approach towards the

systems natural frequency. It will again cause the vibrations but now because of some other

rotating part than teeth frequency B.

Frequency* Value (Hz)

Roller 2.976

Intermediate shaft 7.165

Motor Rotation 20.25

Teeth Frequency B 193.44

Teeth Frequency A 465.69


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However, it is very difficult to practically apply this approach to the Draw Frame Machine. It is

because for that purpose the line speed will have to be change because the roller and line speeds

must be synchronized. Thus if we change the line speed, all the parameters of the Fiber line would

have to be adjusted accordingly. This approach can be used but for that purpose there would be

shut down of the plant and it is also possible that the new line speed does not match the process

requirements.

ii) Put Damping Media at the Machine Base:

This is the other approach that can be used to minimize the vibration. Different damping media

are available that can be used between the contact point of the machine base and the ground.

However the application of this approach well again require plant shut down to put the media at

the base.

iii) Change the mass of the machine body:

This is the most practical and easily applicable approach that require no or very little machine shut

down. In this approach we increase the deviation between the systems natural frequency and the

driving frequency by not changing the driving (and thus line frequency as discussed above)

frequency, rather the systems natural frequency.

The systems natural frequency can be changed by either changing the systems stiffness (k) which

requires changing the geometry or material property or by changing the mass (m) because the

natural frequency of undamped system is given by:

Natural Frequency =

.. The mass of the system can be easily changed by just adding / removing certain mass to/from the

machine wall at appropriate location. In this way the system natural frequency moves away from

that driving frequency which causes the vibration and thus natural frequency will not be activated.

As it is easy for us to add mass rather than remove it from machine, so we will use this approach.

The current system response and the response after the mass has been added is given in detail as

under for both the cases of the line speed i.e. nominal speed and current speed.


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Vibration Response Analysis and Effect of adding mass:

Draw Frame II machine is an undamped, harmonic forced driven system whose equation of

mathematical model can be developed by applying the newtons second law to the system having

a mass m, stiffness k and acceleration

m+ kx = Fo.cosdt (1)

where Fo.sindt represent the harmonic behavior of the driving frequency whose maximum value

i.e. Fois determined by the torque of the motor that is transmitted to the gear teeth in the form of

the force and dbeing the frequency of the harmonic force.

Our objective is to find out the response x as a function of time i.e. x(t). Above differential has

both general solution and a particular one. Its general solution of

m+ kx =0

has the form:

X(t) = A sin(nt + )

Where n =

(A)

The values of the constants A and are determined using zero initial conditions i.e. X(0) =xo

and (0) = vo. The Final form of the general solution that we get is:

x(t) =. sin nt + xocos nt

and the particular solution assumed is:

xp(t) = X cos dt

solving for the constant X we get the final form of the particular solution as:

xp(t) =

. cos dt


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Where = Fo Adding general and particular solution we get:

x(t) = . sin nt + (xo- ) cos nt+ cos dt (2)

This is the final form that gives us the solution in the form of displacement xas a function of time.

As is evident from this equation the response depends upon the driving frequency as well as the

natural frequency of the system.

In our solution we will use zero initial condition for the sake of simplicity. Using = 0 andxo = 0and using trigonometric identity cos ucos v = 2 sin (

) . sin (+

) , the above equation

gives us:

x(t) =.

. sin (

. t) . sin (+

. t) (3)

as is clear from the equation that the maximum value i.e. peak value of the displacement is give as

xpeak=.

(4)

Equation 3 and 4 will be used for determining the response of the system for both the nominalspeed and the current operating speed. Thus both the System Response and the effect of adding

mass are given below at:

1) At Nominal Speed:

For the nominal speed the parameters that are used in the equation 3 are listed here:

n = 149.3 Hz = 938.08 rad /s

d = 151.4 Hz = 951.27 rad /s= 0.997 N / kg (calculated from 4)These values are used in the equation 3. The solution and the graph of the vibration response was

calculated and plotted using MATLAB software the code of which is given below.


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MATLAB Code

f0= -0.997;wn= 149.3*2*pi; %145.70 for 5 percent increase in the masswd= 151.3*2*pi;t = 0:0.00005:1.5;

A=2*f0/((wn^2)-(wd^2));B=sin(((wn-wd)/2)*t);C=sin(((wn+wd)/2)*t);

fori=1:30001Response(i) = A*B(i)*C(i)*1000;

end

plot (t,Response);xlabel 'Time (sec)';ylabel 'Displacement mm';

Response Graph:

MATLAB generated following result for the vibration response:

Response without adding mass


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This graph shows that the maximum value of the displacement comes out to be 0.08 mm which is

verified by the vibration measurements. Beats are formed which is a clear indication of the

resonance phenomenon.

Effect of Adding Mass:

If we add the mass to the system, its natural frequency will be reduced and thus resonance

phenomenon can be avoided. Now we will verify this fact. Assume that the mass of the system has

been increased by 5%of the total body mass. The change in the natural frequency is given from

the equation A will be .05. Thus the new systems natural frequency is given by:

Changed natural frequency=

.05x 149.3 = 145.70Hz = 915.5 rad /s

Putting this new value of n in 3 in the same MATLAB Code and getting the response as above

yields:

We see that the peak value of then displacement has been reduced significantly and it is just 0.03

mm as compared to the 0.08 mm without adding mass.

Response after adding 5 %


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Similarly if we increase the system mass by 10 %the resulting effect is:

f0= -0.997;wn= 142.3*2*pi;wd= 151.3*2*pi;t = 0:0.00001:1;



end


Thus peak value of displacement in this case is only about 0.018 mm. As we keep on increasing

the mass to the system, vibrations are reduced much significantly even at the nominal speed.

However we cannot increase the mass from certain safe limit otherwise the systems natural

frequency will be reduced to 15.84 Hz as was given in the table.

Response after adding 10% mass


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2) At Current Line Speed:

Similar calculations can be performed for the line speed of 230 m / min. For the this line speed

the parameters that are used in the equation 3 are listed here:

n = 149.3 Hz = 938.08 rad /s (same)d = 193.4 Hz = 1215.17 rad /s

= 2.084 N / kg (calculated from 4)Using these parameters, the equation 3 has been solved and plotted in the MATLAB. The code of

which is given as:

MATLAB Code:

f0= -2.084;wn= 149.3*2*pi;wd= 193.4*2*pi;t = 0:0.000005:0.5;



end


Response Graph:

The vibration response that comes out of MATLAB is given below. As can be seen that at this line

speed of 230 m/min, the teeth frequency B is much away from the natural frequency of the system

as compared to the nominal line speed of 180 m /min.

This is the reason that the peak displacement in this case is much smaller i.e about 0.008 mm.

However still the vibrations are in the critical range that needs to be reduced.


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Effect of Adding Mass:

Exactly similar calculations were performed to determine the effect of adding mass to the system.

The same phenomenon of the reduction in the natural frequency of the system takes place. The

results are presented here generated in the MATLAB software.

After adding a mass of 10% of the Draw Frame II machine body to it, the result is:

Response without adding mass




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Conclusion:

Vibration analysis of the Draw Frame Machine was comprehensively studied and analyzed. The

results presented here suggest that the most efficient way to reduce vibrations is to change the

natural frequency of the system i.e. of the draw frame machine body. This can be done by

increasing the mass of the

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