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2014 POLYESTER PLANT Submitted To Mr. Raza Ali (Area Manager Polymer Section) Submitted By Abdul Hayee M. Nasir Aaqib Ali Junaid Aftab Page | 1 IBRAHIM FIBRES LTD.

Ibrahim fiber internship report (PU)

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Polyester Plant 2014

POLYESTER PLANT

Submitted To Mr. Raza Ali

(Area Manager Polymer Section)

Submitted By Abdul Hayee

M. Nasir

Aaqib Ali

Junaid Aftab

Usman Saleem

Date Of Submission 12-07-2014

Discipline Chemical Engineering

DECLARATION

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IBRAHIM FIBRES LTD.

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Polyester Plant 2014

Mr. WaleedManager Training Ibrahim Fibers Limited, Polyester Plant.

Dear Sir: Submitted for your review is our internship report for Ibrahim Fibers Limited, duly completed within the deadline. We hereby declare that the report is submitted in long report format, as per the guidelines and is based on peer reviewed information as guided by our instructors and supervisors at the plant facility. Regards

AbdulHayee| M.Nasir|Aaqib Ali |Junaid Aftab|Usman Saleem|

Institute Of Chemical Engineering (ICET)- University Of Punjab-Quiad e Azam Campus-Lahore

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ACKNOWLEDGMENTS

We are thankful to Almighty Allah for His unlimited blessings and bounties; for keeping us

sane, sound and successful, Our parents for all their support and trust in us, Our Instructors Mr. Saeed and Mr. Haseeb in the Polymer Section. Mr.Faqeer Muhammad, Senior Deputy Manager Utilities. Mr.

Ahamd Aata Area Manager, Spinning and Fiber Line 1 for all his guidance and help. We are also thankful to all the shift engineers, operators and every individual who has helped us even a bit for

the completion of this report.

Table Of Content

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1………………………………………………… Polymer & Polymerization

1.1……………………………………………. Types of Polymers

1.2……………………………………………. Types of Polymerization

2………………………………………………… Polyester

2.1…………………………………………… Properties of Polyester

2.2………………………........................... Uses of polyester

3………………………………………Industrial Preparation of polyester

3.1…………………………………………….Pure Terepthalic acid

3.2…………………………………………….PTA Transportation

3.3……………………………………………PTA Handling

3.4……………………………………………PTA Conveying

3.5……………………………………………PTA Charging

4………………………………………………..Mono-Ethylene Glycol

4.1……………………………………MEG unloading & Transportation

4.2……………………………………Ethylene Glycol Recovery

5…………………………………………HTM & Furnace

6…………………………………………Additives

6.1…………………………………………Titanium dioxide

6.2…………………………………………Catalyst

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7…………………………………………………… Process

7.1……………………………………………… Paste Preparation

7.2………………………………………………Esterification

7.3………………………………………………Polycondensation

8……………………………………………………Spinning Section

8.1………………………………………………Spinning Discription

8.2……………………………………………….Pumping of Melt

8.3……………………………………………….Formation of fibre

8.4……………………………………………….Spin Wall

9…………………………………………………..Quench Air

10……………………………………………………CTR

11……………………………………………………Auxiliary Section

11.1……………………………………………..Cleaning of Spin packs

12…………………………………………………….Textile Lab

13……………………………………………………..Utility Section

13.1………………………………………………Water treatment

13.2………………………………………………Cooling tower

13.3……………………………………………….Chiller

13.4……………………………………………….Compressor

13.5………………………………………………………..Boiler

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13.6……………………………………………………….Nitrogen Generation

13.7……………………………………………………….Technical Nitrogen

13.8……………………………………………………….Pure Nitrogen

14…………………………………………………………….Draw Line

15……………………………………………………………Baler & Cutter

16……………………………………………………………Safety

July 29, 2011

1. Polymer & Polymerization:-

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Poly mean many and mer mean molecules. The process in which smaller molecule unit (monomers) combines to form larger molecule unit(polymer) is said to be polymerization.

Monomers ---------------------------- Polymer

1.1 Types of Polymers:-

There are following types of polymers

1. Thermoplastic polymers2. Thermosetting plastic polymers

The polymer which can be reheated and remolded several times without significant change in their properties is said to be thermoplastic polymers. It is manufactured by addition polymerization reaction.

The polymer which can be heated and molded once and cannot be reuse again is said to be thermosetting plastic polymers .it is manufactured by condensation polymerization.

1.2 Types of polymerization:-

There are following types of polymerization.

1. Addition polymerization.2. Condensation polymerization.3. Ring opening polymerization.

When small molecules joined together in the presence of heat, catalyst or radiations with the elimination of small molecule such as water or alcohol then the polymerization is said to Addition polymerization. e.g. formation of PVC.

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CO

OHC

O

OHCH 2 CH 2 OHHO

Polyester Plant 2014

When the polymer is formed with the elimination of small molecule such as water or alcohol then the polymerization is said to be condensation polymerization. e.g. formation of Polyester

The formation of polymer by the opening of ring such as those of others e.g. Formation of nylon 6 from caprolactan.

2. Polyester:-

Polyesters are polymers that contain ester linkage groups along

their main chains. The International Standard Organization (ISO) defines

polyester fibers as those from polymers based on a diol and a terephthalic acid. PET is a polycondensation product of ethylene glycol and tere phthalic acid (or dimethyl tere phthalate). Polymerization of PET proceeds a two-step process in which the first step is a reaction between a 2-to-1 ratio of ethylene glycol and terephthalic acid (or di- methyl terephthalate) that leads to the formation of bis(hydroxyethy1)tercph- thalate (BHET). In the second step, trans esterification of BHET yields PET.

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↓CH2 CH2 CH2 CH2

O O

O

C

O

C O O

2.1 Properties of Polyester:-

1. Extreme versatility in process.2. Excellent heat and chemical resistance.3. Good electrical and mechanical properties.4. The surface of fiber is rough.5. The fiber of polyester is static in nature.

2.2 Uses of polyester:-

1. Major use of polyester is in textile industry.2. It is used in aeronautical parts.3. It is used in laminates.4. Polyester used in the manufacture of synthetic resins.

3. Industrial Preparation of Poyester Raw material used for the preparation of polyester.

1. Pure terepthalic acid (PTA)2. Mono ethylene glycol (MEG)

There are two additives used in the polyester industry.1. Titanium dioxide (TDO)2. Antimony triacetate as a catalyst

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HTM oil Sanotherm used as a heat transfer in polyester industry.

3.1 Pure Terepthalic Acid (PTA):-

Pta is a petroleum product in powder form. Pta is bi-carboxlic acid formed by the oxidation of para-xylene in the presence of acetic acid. It is white crystalline powder and it is explosive when it is exposed to air therefore we use nitrogen as conveying medium. Different brands of Pta are Mitsui (Japan),Amoco(USA),T-Kong(Korea),ICI(Pakistan,UK),inter quisa(spain).

Properties & Structure of PTA

Color White powderMolecular weight 166.14 g/mole

Particle size 70~160 micronMoisture <0.2%

Impurities Acetic acid,Mo,Cr,Ni,Feph 2.16

3.2 PTA Transportation:-

PTA is imported at Karachi port from there Pta is sent to polyester plants either through bags or either through container. Each trailer contain 35~50 bags.PTA bags is unloaded and stored in warehouse of capacity of ~6500 bags. Each bag carry 1100 kg of PTA and container has capacity of 22000kg. from warehouse PTA is stored in Storage silos according to desire circumstances. Each bag is pneumatically charged to the main

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storage silos. Ibrahim fibers use PTA manufactured by following two companies.

1. Lotte Pakistan2. Siam mitsui

The plant produces 600 tons/day of PET. Whereas the PTA required is 860 kg/ton of PET. Therefore, daily consumption of PTA is 516 tons/day.

3.3 PTA Handling:-

Ibrahim Fibers Limited uses PTA in pure form instead of impure form. This pure form ensures the achievement of high quality products.PTA is highly explosive so extra care is needed for handling of PTA . Storage of PTA requires special precautionary measures Protection of PTA from moisture is also necessary otherwise agglomeration will take place and the quality of the product may decrease.

3.4 PTA Conveying :-

PTA is highly explosive when it came in contact with 5% oxygen. It will form a mixture by reacting with oxygen which is extremely explosive therefore we cant use pure air as a conveying medium because air also contain 21% of oxygen by volume. We need inert source by conveying PTA. The rest 79% of air by volume is nitrogen and it is inert and it will not react with PTA and do not disturb the equilibria during conveying.

Nitrogen is separated from air by utility department and provide it for the conveying of PTA. Nitrogen gas is first filtered in a bucket-type filter and is then compressed in rotary type compressors. After passing through these compressors, both the temperature and the pressure of nitrogen are increased. This nitrogen is then passed through a shell & tube heat exchanger, where cooling water is present on the shell side and nitrogen is present in the tubes. The temperature of nitrogen is reduced from 240oC to about 55oC. This

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compressed and cooled nitrogen is again filtered to remove any PTA particles present. Nitrogen gas is then used for conveying of PTA.

3.5 PTA Charging:-

There are two charging system used for the charging of PTA into main silos.

1. Bag charging system.2. Container charging system.

Which charging system is in use depend upon the circumstances.

In bag charging the polymeric bag the hoist lift the polymeric bag to charging station. Bag is lifted toward the feeder where the bag is cut from bottom and discharge of PTA from bag start taking place. Feeder contain vibrating mesh plate to avoid the transportation of any coarse particle. There is rotary feeder/valve in the conveying line of PTA from feeder whose rpm are controlled to adjust the flow rate of PTA toward the buffer silo. Feeder feed the PTA in buffer silo 1204-V01. At the discharge of buffer silo there is rotary feeder provide path to PTA toward conveying nitrogen line which convey PTA toward the main storage silos 1204-T01, 1204-T11 and 1204-T12. Storage of PTA in desired silos is controlled by using divergence valve. After conveying PTA nitrogen is filtered and compressed in compressor for again conveying of PTA toward storage silos. After compression the temperature of nitrogen shoot up and then it is cooled by using heat exchanger. The amount of oxygen is controlled by using interlocks.

PTA imported from Thailand comes in containers. A container charging system is therefore present for charging of PTA from containers. Container is loaded on the charging station. Inclination is provided and PTA is introduced in the feeder 1204-X57 after screening of any undesired particles. From the feeder, compressed Nitrogen (N2) carries PTA to the silos 1204-T01, 1204-T11 and 1204-T12.

Silos are large vessels cylindrical in shape with conical bottom. PTA feed is stored in these silos. IFL-1 has one silo named as 1204-T01, IFL-2 has

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two silos named as 1204-T11 and 1204-T12. Also IFL-3 has two silos named as 1214-T11 and 1214-T12. These silos are equipped with level transmitters which show an alarm if PTA level reaches high or low set-point level. PTA is transferred from these silos to the feed vessels/day silo with the help of compressed nitrogen when required. Storage silos is provided with pseometer ring used for the purging of PTA stored in main silos this is done to maintain pressure in the silo and to avoid the Agglomeration of PTA in the storage silos. There is Rotary feeder present at the bottom of the Storage silos which control the flow of PTA toward the conveying nitrogen which carry PTA toward the Day silo for further operations.

Schematic Flow Sheet Of PTA Section

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4.Mono-Ethylene Glycol(MEG):-

Mono Ethylene Glycol raw material for PET manufacture, is a crude oil refinery product in liquid form, mostly imported from two countries.

1. Mobil (Saudi Arabia) 2. Equate(Kuwait)

MEG is transported from these countries by ships, from where it is off-loaded at Port Qasim Karachi. From there, MEG is sent to IFL Plant site on MEG tankers of capacity of 40.0 tons. Each MEG tanker has two chambers 20 tons each chamber.

Properties & Structure of MEG

Molecular weight 62.03 g/mole

Boiling point 197 centigrade

color NO

taste Mild sweet

Specific gravity 1.116

4.1 MEG Unloading & Transportation:-

Unloading of MEG starts with the arrival of the container trucks to the unloading area of MEG. MEG is unloaded from tankers with the help of a centrifugal pump assembly. Two centrifugal pump assemblies are present in case if one pump malfunctions then other pump is utilized.

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Each centrifugal pump assembly can be isolated by closing the butterfly valves while the MEG passes through a fully opened butterfly valve into a strainer which contains a mesh to remove any solid particles from the feed of MEG.. It then passes through a globe valve where the flow rate of MEG can be adjusted. Then globe valve is used to adjust the flow rate of the feed .Flow rate of MEG is determined by passing it through Micro Motion a flow rate sensor, after which MEG is filtered again by a bucket type filter which contains a fine mesh to remove the undesired impurities from MEG.

MEG then enters a 3 way valve. The valve directs it to one of the two MEG storage tanks, 1107-T01, and 1107-T02 for IFL-1. One tank is filled at one time. The total capacity of the tanks is 2000 tons/each. Each tank is equipped with level transmitters which generate the low level alarm and High level alarm if MEG level in tanks reaches the fixed set-points. The tanks are filled up to a maximum level of 90%. Prior to the storage, MEG is pumped to a flow meter that shows both flow rate and quantity. The flow rate of pump is 2000 kg/hr.

The sample of MEG is taken from sampling point and send to chemical lab for testing of moisture and for the determination of viscosity. The moisture content of MEG is determined as it should not exceed 1%.if it exceed 1% then it will not suitable for processing.

The PET produced in esterification requires 340 kg/ton of MEG. The daily production of PET is 600 tons/day. Hence, 201 tons of MEG is required each day. MEG is transported from the storage tanks to the processing section in the building by pumping through centrifugal pumps.

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4.2 Ethylene Glycol Recovery:-

The MEG produced in the second reaction contains moisture, aldehyde and monomer the combine mixture of these components is said to be SLUG. From this sludge, we are concerned with the distillation of MEG and water. The boiling point of MEG is 197oC; hence it is recovered as bottom product. Water is obtained overhead and is drained and this type EG is called as Spent EG.

1. The spent-EG is introduced to kettle type evaporator. The evaporator is fed form the MEG storage vessel 3101-V01. This evaporator heats the feed by the Heat Transfer Media (HTM) moving in coils. The temperature of this kettle type evaporator is maintained at 165oC. SEG and other low boilers are vaporized, while very high boilers settle down as sludge which is discharged continuously with the residue pump into the waste barrel each weighing 225 kg. The MEG and H2O vapors in the kettle are then introduced at the sixth plate of a bubble-cap type distillation column.

2. The distillation column in EGR section has 16 plates with a bubble-cap arrangement which ensures the maximum possible separation of SEG

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and H2O. They are assembled in bubble cap arrangement with average tray temperature of 120oC. The whole column is operated under vacuum conditions of 300 mbar. This vacuum is created with the help of eccentric type vacuum pumps. The water is evaporated and is collected at the top in a condenser 3101-D01. The condenser is a shell & tube type heat exchanger with vapors at the shell side. Part of the condensed water is refluxed while remaining is sent for treatment. At the top, the water vapors escaping from the distillation column are sent to the shell side of a condenser (3101-E02) and are condensed by cooling water present in the tube side. The vapors condense and go inside a reflux vessel 3101-V02.

3. This condensate is used as reflux in the distillation column. A pneumatic operated control valve controls the amount of reflux entering the distillation column. The reflux vessel is equipped with a sight glass to see the level. A fixed level is maintained and the overflow is drained off into a vessel 3101-V03. A vacuum pump assembly removes the uncondensed water vapor from the condenser. The vacuum pump sucks the uncondensed vapors through the condenser. These vapors enter the shell side while the chilled water enters the tubes of the condenser and partially condenses the vapors while some are still left uncondensed. The mixture of the vapor and liquid water then is forced into a knock-out drum where the left over vapors are also condensed and then the condensed water goes inside a storage tank 3101-V03. A fixed level is maintained in the vessel and the overflow is drained. Recovered ethylene glycol (REG) is removed from the bottom of the distillation column and is collected in the sump. The level of the sump is maintained

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at 70% while the overflow is drained into the vessel 3101-V04.

5.HTM & Furnace:- Processing (esterification or polycondensation) are endothermic

so heat is require for processing we need any source for heat transfer therefore we use HTM oil we have to achieve >250 centigrade temperature. The process is very sensitive and a change of even 0.3oC can cause drastic effects on the process. There should be following properties of HTM.1. Low viscosity 2. High thermal conductivity3. Low freezing point4. Thermally stable5. High flash point6. Non flammable7. High density

There are two HTM used in IFL.1. Liquid – Santo therm (Phenyl Benzene) is used for primary heating.

The heating of HTM is carried in 3007-F11/12/13

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2. Vapor – Dow therm (Biphenyl Ether) is used for secondary heating. It have 258 boiling point.

Properties of Sanotherm

Avg Mol weight ~240

Pour point < -10oC

Boiling point 340oCAuto ignition temperature ~380

Flash point ~170oC

Properties of Dowtherm

Molecular weight 165.76Freezing point 12.3oC

Flash point 115oCBoiling point 2560C

Ignition temperature 615oC

The HTM is heated in a top fired furnace which is fired with the help of either Natural Gas or Bunker’s Crude Oil (BCO). This BCO is stored in an 1127 vessel from where it is moved to 3007-V03. The level of this vessel is maintained from 50-80%. Positive displacement pumps are used for its transfer.

Two furnaces are being used for the heating of HTM vessel. 3007-F01 & 3007-F02. One of these is standby furnace. It must be noted that the standby furnace in this section is not kept completely out of order. The furnace in operation is fed at 343 m3/hr. whereas standby furnace receives 20 m3/hr. of HTM. The temperature of the furnace is 327oC.

In the furnace, Natural Gas is used in the furnace while Santo therm is used in the coils. Natural Gas enters in a ball valve and then through a strainer to remove any solid particles and impurities. It then passes

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through a Pressure Regulating Valve (PRV). Then it reaches furnace through a Blocking Tightness Control.

This system consists of two XV valves. The gas through first XV valve and is closed. The pressure of the gas is measured. If pressure of the gas does not change then it is sent through second valve for ignition. The furnace is ignited with the help of LPG when ignited for the first time as LPG has higher burning value.

The flue gases from the furnace are passed to an economizer which is a Shell & Tube heat exchanger system for heating the air. Flue gases pass through tubes while air passes through the shell side. The temperature of the air is raised up to 200oC before entering the furnace. After heating, stack gases are emitted into the atmosphere.

HTM is built up in a 3007-V01 vessel and is constantly heated to reduce viscosity. Its level is checked with the help of a Magnetic Level Indicator. It is then moved to 3007-V02 vessel at 25 m. If the level of 3007-V01 falls, then barrels of HTM are charged each weighing 230 kg. The level of 3007-V02 is maintained at 50%. If there are any leakages in the HTM system, then they are directed to 3007-V04 at 0 m. The lines entering the furnace are also provided with steam tracing for easy flow and good atomization of HTM.

In any operation, HTM is used as two systems. In coils as liquid and in vessel boundaries as vapors. Santo therm is used in the primary cycle where it is heated in the furnace. This Santo therm then moves in coils to a secondary cycle where it is used to convert Dow therm into vapor state in an evaporator. This Dow therm is used in the linings of the vessel to maintain the temperature of the mixture and to make sure efficient heat transfer throughout.

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6.Additives

Two additives used in polyester industry.

1. Titanium dioxide2. Catalyst

6.1 Titanium dioxide:-

Titanium dioxide is a white powdered solid .In fiber making process, it is used as dulling agent in the second stage of esterification process. It is used to make products of different brightness.

For making a semi-dull product, the concentration of TDO in the solution is 10% and 0.3% by weight of PET in the final product. On the other hand, a bright product must have 3% concentration of TDO in solution and 0.03% by weight of PET in the final product.

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TDO bags are added through 20 small bags of 25 kg each or 1 big bag of 500 kg in the feeder. TDO is then directed to 1307-V01 vessel where it is agitated for 4 hours. This mixture then moves to 1307-V07 where 1610 L of EG are added. It is again mixed for 1 hour before moving it to centrifuge (1307-A02). In centrifuge, the concentration of TDO is 18% and mixture enters at a set point of 452 L. The centrifuge separate oversize and undersize particles. The coarse particles are produced due the agglomeration caused by the charges developed due to agglomeration.

Peelers in the centrifuge remove coarse particles and send them to 1307-V08 and then to the Pearl Mill (1307-A01). Pearl Mill grinds the oversize particles by using a Muller which has fine particles of Zirconium dioxide of diameter 0.8 micron. Ground particles form pearl mill are again moved to 1307-V01 vessel.

Mixture from 1307-V02 is now separated into two lines for making products of different properties i.e. semi-dull and bright. 1307-V03 is used for making semi-dull product of 10% TDO concentration. Bright product is made up in 1307-V04 vessel from where it enters 1307-V05 vessel in which 4363 L of EG are added to reduce the concentration of TDO up to 3%.

TDO has following advantages for the final product.1. TDO provides matt finish to the final product. 2. It increases the durability of the product. 3. TDO also gives hardness to the product

6.2 Catalyst:- The process of fiber making is an endothermic reaction. It means that the energy required to start reaction is high. To lower this energy, called as activation energy, catalyst is used. Catalyst lowers the activation energy by associating itself with the reactants which also helps in reducing the residence time.

The catalyst used is Antimony Triacetate Sb(CH3COO)3 or Di-antimony Triacetate Sb2(CH3COO)3. It helps the reaction in the stage of polycondensation which will be discussed later. It is imported in the

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form of bags, each weighing 15 kg, from USA. It occurs in the form of granules and is fed as two catalyst vessels. Antimony triacetate is imported from USA in the form of white crystalline powder in 12.5 kg buckets. Active site of catalyst is Sb+++.1. Feed vessel2. Catalyst vessel

Solution of catalyst is prepared by mixing filtered ethylene glycol and Sb(CH3COO)3 in a vessel at a temperature about 75-80oC. The solution is agitated constantly for 4 hours in the vessel, while 1 hour is provided as settling time. At the end, an analysis is done to ensure that the concentration of the catalyst in the solution is 3%. The preparation of the catalyst solution is done batch-wise. A number of batches of catalyst solution are prepared to ensure that continuous process of plant does not stop.

Prepared patch of catalyst solution is filtered and a fixed amount of is introduced in the paste preparation unit (170-180ppm of catalyst in product is desired). The amount of catalyst in the final product is so low that a process for recovery of catalyst is not feasible.

7.1 Paste Preparation:-

After the preparation of all the raw materials and catalysts, the process is now taken to next stage of paste preparation in which all the components are mixed in such a way that they form a paste which is then further taken to the main reaction vessel

The PTA prepared in the PTA section is stored in day silos. From these silos, PTA is carried by pressurized N2 to a day silo at 25 m top of the IFL-1. The mixture is filtered prior to its entry into the silo. In the day silo, PTA settles down while N2 leaves the silo through nitrogen discharge system. The PTA then enters a Schenk System which consists of a motor operated rotor assembly. This system is attached for the proper distribution of PTA in the paste tank. PTA enters the tank at a mass flow rate of 7000 kg/hr.

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Mono-ethylene glycol from these three lines enters the paste making vessel which also contains crystalline PTA. The mole ratio of the reactants is very important. In the paste making vessel the mole ratio of MEG to PTA is maintained at about 1.12. This ratio is also called E/T ratio i.e.

ETRatio=Molesof MEG

Moles of PTA=1.12

A solution of catalyst (antimony tri-acetate) in MEG, is present in catalyst feed vessel 1402-V01. Screw pumps are used to transport the catalyst solution from the feed vessel to the paste tank. On its way to the paste tank, the catalyst solution passes through strainers in order to remove any suspended particles. The preparation of the catalyst solution will be discussed later in the report.

As the reactants and the catalyst solution enter the paste vessel, they are agitated with the help of a fix speed agitator. The residence time for the paste is about 3 hours. The temperature in the vessel is 45oC and the capacity of the vessel is 29m3. From this vessel, the paste is pumped to the esterification reactor with the help of screw pumps.

7.2 Esterification:-

Esterification reaction is the main reaction taking place in polyester plants. In an esterification reaction, an acid reacts with alcohol to form ester. In our case, pure terepthalic acid reacts with mono-ethylene glycol to form Bis-hydroxyethyl terephthalate. The reaction is given as:

2(HO-CH2-CH2-OH) + HOOC-C6H4-COOH (HO-H2C-H2COOC-C6H4-COOCH2-CH2-OH)+ 2H2O

The paste from the previous section is transferred to the esterification reactor-1 (ES-1) in which the esterification reaction takes place. It is a continuous stirred tank reactor (CSTR) which has a capacity of 50m3. Inside the reactor are spiral coils through which Santo-therm

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(Therminol-66) passes and heat the system to about 258oC. Pressure is maintained at 0.16 bar. The reactor is jacketed and Dow-therm is passed through the jacket, which heats up the wall of the reactor to prevent scaling. The agitator provides continuous mixing and improved heat transfer.

The reaction taking place in esterification reactor is endothermic and thus the rate of reaction is enhanced at higher temperatures. the reaction time is about 4 hours and about 90-95% conversion of reactants into product takes place. Water and MEG vapors emitted in the reaction are constantly removed and are transferred to the process distillation column for distillation.

The product formed in ES-1 is then divided into two lines, each line entering separately in two esterification reactors named as esterification reactor 2 (ES-2) in each line (14&15). They are coded as 1421-R02 and 1521-R02 respectively. These are also jacketed vessels equipped with agitators. Spiral coils are present inside the reactor through which Santo-therm moves and raises the temperature. Dow-therm maintains high temperature at the reactor walls.

ES-2 reactors have relatively less capacity than that of ES-1 (11.8 m3). An important step in the ES-2 reactors is the introduction of dulling agent Titanium Di-oxide (TDO). TDO is introduced in each reactor depending upon the level of brightness of product required. Semi-dull product is produced by introducing 0.3% TDO in ES-2. Semi-dull product is being made in line 14. Similarly, for bright product 0.03% TDO is added in ES-2. Bright product is being formed in line 15.Water and MEG vaporized in each ES-2 reactor is also transferred to internal distillation column where it is fed at the sump of distillation column. SEG is obtained from the distillation column.

MEG vapors obtained from ES-1 as well as ES-2 reactors, if contain less amount of impurities are recovered in a distillation column located inside the building named as process column. It is a 16 plate, bubble-cap type distillation column which is being operated at atmospheric pressure. HTM is used for heating. The bottom temperature is

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maintained at 180oC and the top temperature is set at 100oC. SEG obtained from the process column is then fed to the paste vessel.

7.3 Polycondensation:-

When the polymer is formed with the elimination of small molecule such as water or alcohol then the polymerization is said to be condensation polymerization. e.g. formation of Polyester. Poly-condensation reactions are playing important role in modern industries especially their use in manufacture of synthetic fibers. Polyester is formed by poly-condensation of Bis-hydroxyethyl terephthalate (BHET). Poly-condensation reactions are temperature and pressures sensitive therefore a good control over the reaction conditions is very important. The generation of monomers as well as controlling the chain length are some important factors in the polymerization reaction. Our fiber formation process, monomer formed in ES-1 and ES-2 is transferred to polymerization reactors in which poly-condensation takes place with the release of MEG vapors. Three polymerization reactors are present in IFL-1 named as PP-1, PP-2 and DRR (Disk Ring Reactor).Water formed in polycondensation is removed through distillation.

Polymerization in PP-1 is carried out at temperature of about 257.2oC. Heating media is Santo-therm present in coils within reactor while Dow-therm is present in the reactor jacket. Vacuum pressure of 118 mbar is maintained with the help of vacuum pumps. No agitator system is provided in PP-1 reactor, although due to presence of vacuum a swirling movement is induced in the feed. The level in the reactor is maintained at 35% and a capacitor type level indicator is being used to measure the level in the reactor. During the polymerization, MEG vapors are produced which are constantly being fed to a scrapper condenser in which liquid MEG (condensed) is showered and MEG vapors are condensed. A scrapper is present in the condenser which removes any solid deposited on the condenser surface.

Vacuum is created in the PP-2 reactor and a pressure of about 15 mbar is maintained. Pre-polymer solution from PP-1 is brought to the PP-2

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reactor. An agitator is employed in PP-2 for proper mixing, as the intrinsic viscosity of the mixture increases. The temperature is maintained at 259.7oC and the level in the reactor is set at about 35%. The level in PP-2 reactor is measured by capacitor system as well as radio-active level measuring system. MEG vapors produced in PP-2 are removed and condensed by a jet system discussed later in the report. The mixture from PP-2 is then filtered in candle type filters and is then transferred to the final poly-condensation unit (DRR).

DRR is a horizontal plug flow reactor operated at about 282oC and a vacuum pressure of about 0.8-1.4 mbar. A horizontal agitator having discs is used for proper mixing. The level in DRR is maintained at 31% and is measured using radioactive level measuring system. Molecular PET is poly-condensed to high molecular PET in the final poly-condensation reactor. In DRR, pre-polymer is brought to its final viscosity and properties. Intrinsic viscosity is used to as a parameter for determining the chain length. The degree of poly-condensation and thus viscosity is set to the desired final value by maintaining vacuum, temperature, agitator speed and residence time at an appropriate level.

Ethylene glycol vapors produced during poly-condensation in PP-2 as well as DRR are removed from these reactors and condensed with the help of a jet system. In jet system, blast EG is passes through a jet to which both PP-2 and DRR are attached. Vapors of MEG produced in these reactors are taken to the jet. This blast EG then enters a 3-stage condenser system in which condensed MEG is being showered. Vaporized MEG enters the first condenser where some part of it is condensed. It then enters the 2nd cooler where again some part of it is condensed. It then enters the third condenser and further condensation of vapors takes place. By using this condensation phenomena, vacuum is created and maintained in PP-2 and DRR. The remaining un-condensed vapors are then vented to the atmosphere.

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8. Spinning Section8.1 Spinning Discription:-

Melt polymer at the temperature of 285-289oC comes from poly-condensation plant through insulated pipe. The melt polymer is heated through HTM (therminol). The temperature of polymer is controlled by HTM used in pipes co-currently.

In IFL-1 this polymer come in five simultaneous beams each beam consist of six packs which sums up to 30.contacted to gear pumps. Because of viscous liquid we use this pump at fix RPMs to through melt

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polymer in spin packs. Each pump have its own pack which through melt into spinnerets

.Below each pump, there is spin pack.

On top of spin pack, a plate is kept containing 3750 holes in IFL-1. Outer diameter of each hole is 0.25 micro meter. Pressurized molten polymer at 288Centigrade and 70 bar is passed through the plate.

Holes are in radial formation. There is fiber formation. These fibers are at 288Centigrade temperatures. The molten polymer is pressurized so that fiber formation can be given to it.

Throughput for semi dull is 98 ton/day and for bright is 95 ton/day. Each pump is controlled by attached reducer. It controls the speed of pump. It also increases torque.

8.2 Pumping of Melt :-

Five beams assembly which contain six gear pumps in each beam used to pump the melt toward the spin pack. Gear pumps are used for the pumping of viscous liquids and it is the type of positive displacement pump.

There are 2 lines in IFL 1 each line contain 30 pumps . the rpms of each pump is fixed to produce a pressure of 70 bars and for the proper distribution on melt in each spin pack.

8.3 Formation of Fiber:- The melt from each gear pump is pump toward the spin pack this is the

portion from where the formation of fiber take place after the series of operations. Spin pack is circular assembly contain spinneret.

Spinneret contain 3750 holes with the outer diameter of 0.25micrometer. melt penetrate these hole and tae a shape of fiber after the formation of fiber the temperature is reduced suddenly by using the quench air.

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8.4 Spin wall:-

Spin wall is an important operation in spinning section. In spin wall there are different functions done by different parts as given below in detail:

a) Slub catcherb) Slot oilerc) Convergence guide(v guide)d) Suction cutting device( nozzle and cutter)e) Drip detectorf) Deflector rollerg) Support guideh) Entangling devicei) Dia-bolo rollersj) Finger guidek) Rollersl) Sun flower

It is a device used to fix positions of filaments. It is used to catch drip in the sub-tow coming from spin pack. Before thread oiler devices, there is ceramic coated rod called slub coater, which holds the filaments bundle for each position. Each position is provided with suction and cutting device, as is used to cut the position as per requirement and waste through hose pipe at the back of the wall. Suction cutting device is operated at air pressure of 6 bars.

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Spin finish oil is showering on the sub-tow coming from the slub catcher to make it friction free and antistatic to avoid dripping. The distance between slub catcher to slot oiler is 190mm. After solidification, the filaments pass through the ring oiler device. The oil is applied to filaments in order to maintain 30% moisture content. Ring oiler device also applies S.F. Oil to the filaments in order to remove the static charge.

V-guide is used to guide sub-tow towards suction and cutting device, it makes sub-tow handling feasible for suction and cutting device. Distance of v-guide to thread oiler is 160mm.

When drip is detected in drip detector, cutter used to cut sub-tow and the remaining sub-tow is sucked on the principle of ejector through suction device. Distance between v-guide and suction device is 50mm.

When drip is detected in drip detector cutting device is used to cut the sub-tow line coming right from the slub catcher. Distance between suction device and cutting device is 50mm.

If there is drip in the sub-tow line is detected, drip detector detects and generates a signal toward alarm. Distance between drip detector to cutting device is 100mm. clearance of drip through drip detector is 0.5 mm. The filaments then passed through drip detector. Whenever drip or plastic comes with filaments, it operates the drip detector and signal comes at the local panel with alarm.

Then the filaments are deflected from vertical to horizontal direction with deflector roller. The deflector rollers are un-driven and one deflector roller is for one position. These filaments are guided with ceramic coated guides. The filaments are gathered from each position in the form of sub tow. Then the sub tow travels at godet rollers and sunflower unit and collected into two at can traversing area.

Sub-tow coming from the drip detector is deflected towards the dia-bolo rollers. These are used to change the vertical position to horizontal position of sub-tow. Distance of deflection roller to drip detector is 115mm.It is used to provide stretch to the sub-tow to make it part of already or continuous running sub-tow.

It used to align the new sub-tow with the continuous running sub-tow by providing a 6.5 bars pressure. These are used to change the direction

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of continuous running sub-tow towards the finger guide. They are free to move therefore they have highest rpm in the spin wall.

It is used to provide the sub-tow adjustment on the motor operated rollers. The six motor operated rollers are used to draw sub-tow from spin walls. Size of each roller is 0.5mm higher than its preceding roller.

Sunflower rollers are used to nip the sub-tow towards the cans in those sub-tows is filled. There are teeth on the rollers which are used to nip the sub-tow.

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9. Quench air section:-

As concern with quenching of air, the blowers in quenching section picks up air from spinning section which is actually comfort air at a temperature of 30-35oc.

After this a part of this air about 30% exhausted and in other part called dampers fresh air is entered at same amount 30%. In winter season environment temperature is 20-25oc, in this situation we take 100% fresh air from environment and the dampers are automatically closed. These dampers twirled automatically which are adjusted with humidity factor.In summer season these dampers operated automatically.

This air send to the bag filters which removes dust particles from air. There are some steam coils which heats up air in winter season as per required our required temperature. after this some dust particles remain in the air which is removed by another section which is washer tank. In washer tank water mixed with some chemicals, air enters and passed.

Washer tank contain a rotary tank which picks up all dust particles. After this air is cooled for further process cooling coils are used which contain chilled water which comes from utility section. After this process air is cooled approximately 18-20oc, then this section divided into two lines one is of comfort air and other one of quench air. Because quench air is used for cooling of polymer which require more efficient and must be dust free for this again this air passes through bag filters which removes dust particles from air. This air through a duct reaches to the spin packs to cool the polymer.

When quench air comes in contact with polymer its temperature is about 20oc. this air is humidify at 85%, because of little residence time of air with melt high amount of air must be there for their proper solidification. After solidification the temperature of air approximately 50oc. this air exhausted through a duct. If our humidity level is lower

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than as given above after solidifying the melt air temperature reaches at 150oc which is inefficient process.

Quench air temperature is important factor, if temperature is increases then in draw line desired properties cannot be achieved. Another important factor in quenching is uniformly distribution of air to all filaments, in case proper supply of air and velocity of is most important. There are 15 lines of holes in spinneret if velocity is lower than the last one lines will not solidify as we need therefore 2.50m/s velocity is efficient for proper heat transfer. If air velocity is high then this can cause filaments fuse with each other.

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10. CTR:-

Can contains sub-tow coming from spinning section also called as UDY (undrawn yarn).

Following are the operations which are existing in the CTR.

1) Conveyer which carries the cans is called as carriage.2) The motion of carriage is controlled by synchronization strip. It is also

called as brain of carriage.3) Sensors are used to define the intake and outtake boundary of can and

generates a signal to the synchronization strip.4) Weight of an empty can is 1 ton.5) Capacity of can to carry weight is 5-5.5 ton.6) One can is filled in 58 minutes.

11. Auxiliary section:-

Auxiliary section in polymer section is an important part. In this section spinneret pack which are used to convert to polymer into fiber is repaired or reassemble. The parts of spin pack which are assemble are given below:

a) Housingb) Filling ringc) Ring distributiond) Perforated platee) Coverf) Spinneretg) Support ringh) Filters ( 5 & 3 fold)i) Gas kits (small & large)

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11.1 Cleaning of spin pack parts:-

In TEG tank five chocked spinneret placed in tank at a temperature of 270oc for 16hours. After this these spinneret withdraw from tank sunk in 5% NaoH solution bath for 1hour then these spinneret placed in other tank of demineralized water. After this cleaning spinneret are cleaned but somehow there holes may blocked, for this we placed it into weave bath. Now this spinneret is go for inspection which is done by a machine on computer. All the holes of spinneret inspected, if found any blocked hole then operator with the help of air or with needle cleaned it out.

Other parts of spin pack like housing, distribution plate, cover etc are cleaned in another section called vacuum pyrolysis. First as all spin pack disassemble then spinneret send to TEG section and other parts are placed in vacuum pyrolysis where at -0.5 to -0.7 bar and at temperature of 450oc for specific time at which cracking of polymer takes place. Then these parts washed with demineralized water for there further cleaning by using max power as a detergent.

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12. Textile lab

Manufactured fiber can be tested in textile lab, following tests are tested as:

a) Denierb) Tenacityc) Elongationd) Crimp noe) Crimp removalf) Shrinkageg) Electric resistanceh) O.P.Ui) Miscut j) Fiber lengthk) Deep dye effectl) Moisturem)Colors (L & b) n) Bulk density

Now we are going to explain these tests one by one on the basis of their operating functions.

As we have taken different samples from different lines like 71 & 73. As denier given by per line lab attendant check its denier with the help of vibroscop.These two terms also tested with help of viscometer.

Crimp number of selected fiber found as, fiber attached with scotch tape then with the help of microscope find its crimp number. A fiber of denier 1.4 must have crimp number 12-13 inches.

Weight attached to the fiber and we find its length after and before attaching weight in this way we find its crimp removal it must be >15%. In this process we take our sample into oven for 20 minutes at a temperature of 180oc.

For this we use static voltmeter, sample 2g is taken and current of 150V passes through it, if its resistance is less than 1*1011 ohm then this fiber is good to use.

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In O.P.U test we take 5g sample in flask which contain 40% solution of methanol and place it in a heating medium and did this process for 20 minutes after this take out flask and place in oven at 120oc for 20 minutes.

Then this sample place in desicator after this due to weight difference which is being measured after and before this process we found out % of oil absorbed in the oil which must be from 0.130-0.140%

This length is checked is checked with the help of slap glass, two points of fiber connected with scotch tape and with the help of scale we found out our required length given by process section.

In this test Illumines weaving plate is used for test which is connected to electric supply. Fiber placed between plates then if the fiber is hard colored its stretching is not possible this is called deep dye effect.

5g of sample taken and weight it. Then this sample placed in oven at a temperature of 60oc for 1 hour, after this weight it then we found the %moisture by using formulas, its maximum rang 0.39 %.

13. Utility section:-In utility section operations are performed given as below:1. Water treatment2. Cooling water3. Chillers4. Boilers5. Nitrogen compressors

13.1 Water treatment:- Water is a major need of industry. As we know, in IFL plants canal water

is not available therefore we use ground water here.. On the other hand ground water contain TDS (total dissolved solid) which are not easy to remove. Conductivity of water in Faisalabad is about 3000-3300 S. μInitially we are tried to reduce conductivity of this water.

Ground water is pumped through 3 turbines & stored in an overhead tank with a capacity of 5300 gallons then supplied to Water Treatment

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Plant for purification. Two pumps pump the water to the top of the two 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.

After filtration dozing of water is done in a tank. For dozing 33% HCL is added in filtered water through control valve. Here dozing is done just to maintain PH of water at 6.3. HCL react with carbonates and remove its hardness, the reaction are given as below:

HCl + CaCO3 CaCl2 + H2CO3

HCl+MgCO3 MgCl2 + H2CO3

H2CO3 +Air H2O + CO2 + Air The filtered water at a pH 6.3 is passed through candle filters called as bag

filters. The water is then pumped through multi-impeller pumps, which generate 25-bar pressure output, which is used as a feed for the Reverse Osmosis unit. In the RO unit we have 6 banks in which filters are fitted. Here almost 70% of the water passes through the cellulose membrane whose conductivity is very low (100 μS), called as Permeate.

The remaining 30% water whose conductivity is very high (10,000-11,000 μS) is disposed off. The soft water is sent to the hydro-cyclones where the air is blown with the help of a blower, which after absorbing CO2 from the water is discharged to the atmosphere. Here 80-85% of CO2 is removed & water is sent to the storage tank. Here soft water used in process section, cooling towers, and in chillers. But in boiler only demineralized water is used.

13.2 Cooling tower:-

In cooling tower water is cooled up to 25-30oc. Soft water from process pump to cooling tower section at 35oc. the basic working principle of cooling tower is the hot water through from the top of cooling tower as shown in the figure below.

This hot water comes down and air from lowers enter cooling tower, when air and water comes in contact with each other evaporation process carried out, and we know evaporation causes cooling effect.

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This Air picks up high energy molecules and with the help of fan at the top sucks it to environment.

At the inner side of lowers there are fillings which prevent the splashing or loose of water. At the bottom of the tower there is slumn which collects the cooled water. This water send to operation with the help of pump and water recycle again.

As we know this is not demineralized water therefore there is definitely chance of attach of fungus and turbidity. To remove it we add some chemicals in it with their trade names. We maintain level of water in slumn in cooling tower. In any case if some water loose in splashing and in evaporation then at the bottom there is vent which is called as make up water. Its function is to fulfil level.

Fan on the top is motor driven at fix RPMs. RPMs of fan play an important role in cooling. Its RPMs will be change under environmental consideration, and it also depends upon wet or dry bulb temperature, cool water the at lower RPMs of fan rather than if difference is lower.

13.3 Chillers:- Chillers are used to chill the soft water. In IFL water is chilled up to 6-7oc. The chilled water circulates in the plant through a closed loop. The

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water returns to the chillers at a temperature of 11-12oC. We have three Water Cooled Centrifugal chillers of 2000 kW cooling capacity. The chilling operation is like a refrigeration cycle. It has mainly 4 parts given as below:

a) Evaporationb) Compressionc) Condensationd) Expansion valve

In evaporation shell & tube heat exchanger is used, where chilled water on tube side and refrigerant is n shell side. The WC (chilled water) stream from the process (11-12oC) enters the evaporator in the tubes & is discharged at a temperature of 6-7oC. It is present in the liquid form & when the WC stream passes through the evaporator tubes, the refrigerant gets heat from the water and evaporates.

After this it send into compression chamber. The compressor should be of such capacity that it should intake same amount of vapors from the evaporator as being produced in it if the capacity is low then the pressure in the evaporator will increase & thus the saturation temperature of refrigerant will increase. When the vapors are compressed their temperature & pressure increases.

After compression this water is send into condensation chamber where cold water is on shell side for cooling purpose. Here the vapors are discharged at the same pressure but at lower temperature & sent to the economizer.

A nozzle is fitted in the economizer, which acts as an expansion valve. Here the vapors are sprayed so their pressure decreases due to sudden expansion cooling occurs & most of the vapors go to liquid form. From the economizer these streams are discharged.

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13.4 Compressor:-

Compressors are used to increase the pressure of a gas. Compressors are very important in industry because at many places in process we require air at pressure higher than the atmospheric pressure. At IFL, the purpose of installing a compressor is,

1. For nitrogen generation 2. For PTA charging

Screw type compressors are used here in positive displacement types of compressors. Five double stage screw type compressors are installed here of capacity 1339 m3/hr, having maximum working pressure 10.5 bar. One compressor is used for normal consumption, and one is stand by, whereas remaining are used depending upon load. There are also four air refrigerant driers.

Double stage screw type compressor takes air from the atmosphere. This air is pre filtered and then it passes through intake filters in order to remove dust and other suspended impurities. In first stage, this air is compressed to 2.7 bars, its temperature rises to 240oC. This compressed air passes through intercooler (Shell and tube type), where water is used as cooling media.

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Temperature of air falls to 35oC. Now it passes through the second stage, where it is compressed to 9.5 bars and its temperature rises to 245oC. It is passed through after cooler where water is used as cooling media and temperature of air becomes again to 30oC. Now this compressed air at 9.5 bars and 30oC enters in air refrigeration dryers.

This air enters into an evaporator, where moisture of air condenses by giving its heat to refrigerant causing it to vaporize. The condensed moisture is drained off. This moisture free air enters again in air to air heat exchanger, where it takes heat from the incoming compressed air. The vaporized refrigerant is compressed in reciprocating compressor. This refrigerant enters the condenser where water is used as cooling media. This condensed refrigerant is again ready for moisture removal in evaporator.

The compressed, dried air is stored in compressed air storage. From the supply of compressed air to process; one stream is taken into the instrument air dryers. They contain two cylinders filled with hygroscopic compound (Al2O3). One cylinder operates at a time, when its pressure becomes high and temperature becomes low and it becomes saturated, its pressure falls and refrigeration occurs. Meanwhile, at the same time other cylinder become active and prepares instrument air. The instrument air produced is stored in vessel.

13.5 Boilers:- The boilers are used for the production of steam, which is then used on

many types of equipments 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,

i. Fire Tube Boilers ii. Water Tube Boiler

Three fire tube boilers are used in the IFL. One is stand by while 2 are in operation. Fuel for boiler: i. Natural gas (mostly used) ii. Furnace oil (stand by)

The steam condensate (70%) returning from the plant comes to the feed water tank where a de-aerator is also attached to remove the air from the steam condensate. In this vessel chemicals are added to condensate.

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i. Hydrazine - for removal of free oxygen ii. Caustic soda - for maintaining pH iii. Ammonia gas - also added for maintaining pH

After the feed water tank the condensate is pumped by two pairs of pumps (one pump of each pair is standby) to the boiler. The condensate along with 30% de-mineralized water enter the boiler on the shell side and converts to the vapors form by heat transfer from the fire entering from the tube side. The level of water in Boiler is 2/3 of total volume of boiler. The steam from the boiler then enters the super-heater at 25-bar pressure and the steam form the super-heater exits at about 250oC.

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13.6 Nitrogen Generation :-

Nitrogen required for the process must be at high pressure and low temperature. Nitrogen produced at IFL is classified into following two types. i. Technical nitrogen ii. Pure nitrogen

13.7 Technical Nitrogen Unit NT is produced in a pressure swing adsorption unit consisting of 1. Air compressor 2. Chilled water air cooler 3. Pressure Swing Adsorption (PSA) Unit

A two stage air compressors giving compressed air at a pressure of about 8 bar. Currently unit is operated is at external supply. Compressed air passes through pressure relieving valve where its pressure reduces from 9.4 bar to 8 bar. This air then passes through chilled water cooler. The water supplied lowers the temperature from 30oC to 12oC, also moisture trapped is removed. This air is transferred to Buffer Vessels containing cyclones, which remove moisture.

Air from the buffer vessel, reaches adsorber-1 through the bottom and flows through the carbon molecular sieve bed. During this process the oxygen of the process air is adsorbed that is attached to the CMS at a high pressure and low temperature. The nitrogen reaches into technical storage tanks

Downstream of anti-storage tanks tubing, takes sample gas to the analyzer for the measurement of O2 contents in the NT produced. The NT flows to the storage vessel or to the atmosphere depending on its O2 contents. If O2 contents exceed the set point, then N2 vents to atmosphere. If O2 contents are within a range, then it flows to NT storage vessel. The regeneration process is of 1 min cycle.

First pressure equalization occurs of both absorbers then the absorber to the regenerator releases adsorbed O2 to the atmosphere and the other come in operation to absorb oxygen. The NT produce from plant A and B is stored. The NT produce must contain O2 <1%. The production of NT takes place at a rate of 195 m3/hr. in each section.

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13.8 Pure Nitrogen Unit It also contains 2 units. Each stream is divided into further two streams; one for each plant. There are two hydrogen cylinders for each plant.

A highly exothermic reaction occurs, forming N2 and H2O vapors. The reaction of hydrogen and oxygen occurs at 195oC and in the presence of Palladium used as catalyst in a De-Oxo Reactor. The reactors maximum allowable pressure is 13 bars and maximum allowable temperature is 240oC.

This stream containing NP and water vapors is passed through finned type heat exchanger to lower its temperature. It is cooled down in the exchanger resulting in the condensation of water vapors releasing NP. The production of nitrogen is 10 m3/hr.

14. Draw Line

In this unit operation section the UDY(undrawn yarn) is converted into DY(Drawn yarn) with physical property change

In this area the can are placed and the sub tow is used to form a larger tow. 25 cans are being used in each line at same time. The formed tows are arranged and guided on rollers. Tow is dipped in dipping both which contain SF oil. Tow is dipped to achieve uniform temperature of 24C and pre-lubrication of tow to avoid slippage and entangle.

The draw frame is used for the drawing of the polymer along its length. 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. The roller speed is kept 62 m/s approximately this is first stage drawing which is also called soft drawing. This is a closed tank where the spin finish oil at 80oC is showered on the tow. The steam in the plate type heat exchanger heats the spin finish oil.

This is the second draw frame present in the fiber line. It has 7 rollers having a rotational speed of 198.5 m/min. The rollers of this draw frame are provided with steam at 95oC to heat them. The drawing is done at glass transition temperature 79oC. At glass transition temperature, the drawing of fiber is done maximum.

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Between DF-II and DF-III, steam is showered to achieve rest of 13% drawing. In DF-III, rollers speed is 235m/min. In this chamber the properties achieved by the tow are stabilized. It has 12 rollers and is divided in to two parts each containing 6 rollers. There rotational speed is 234 m/min. The temperature of tow is kept about 207oC.

This unit consists of seven rollers rotating at 232 m/min. The purpose of the DF-IV is to grip the tow and make a speed control for the next units. 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.

The unit maintains the tension of the roller & again sent to the steam unit to gain the cotton like property. Now tow is crossed through the crimper unit. This unit induces crimps on the fiber at a rate of 14 crimps per inch. The crimps are made for necessary fiber flexibility & cohesion

The tow leaves via traversing unit where spin finish oil is sprayed on the crimp tow depending on the type of product. The traversing chute spreads the tow on the tow drier plate. In this section the tow is dried & cooled. 10-bar steam is supplied for the heating zone.

15. Cutter & Baler

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Fiber tow formed in spinning is at high temperature. It should be cooled, before it is sent to baler and cutting section. Fiber from dryer, moves on chain. In chain there are small holes on chain through which air from atmosphere is sucked by pump. This air cause cooling of fiber.

There may be knots in tow which may damage cutter. Two rollers above another are used in assembly line. As they passes through them , one roller will rise which give alarm. This knot will be cut down by operator. To grip the tow, two rollers are used. These are assembled one above another. They are also called gripper.

The tow coming from tension roller will wind around the cutter. The cutter is circular which contain blades on edge in circular form. These blades will cut down the tow.As tow is cut down, the fiber will fall down on plate that is called free pin. This will be close when plate below it will be opened.

As plate of free pin falls down, it will be collected wear pin. This plate weight the fiber. Upon 50 kg batch , plate will be opened. Fiber is pressed in push pin section. 300 kg pressed batch is prepared. This is packed in polypropylene.

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16. SAFETY PRECAUTIONS In order to avoid the hazards on the plant, company train its employees for the safe handling and operation of materials and units installed on plant Smoking is strongly prohibited on all areas of the plant because at different places different flammable materials are under process and some leakages may occur and so serious damage can occur. Over speeding is prohibited on the roads because staff is always

crossing the roads and also tanks with explosive materials are present at different places and anything hitting them may cause a serious danger.

Mobile phone is not allowed in plant area because electromagnetic waves may disturb the sensitive control system. For the training of internees, schedules are issued that means that for every unit some guider is provided for the specific period of time and we are not allowed to go in any area according to our desire.

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