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DOC. NO.: 09035-00-GIN-PR002

JOB NO. : 2009035

DESCRIPTION OF PROCESS SECTION

PROJECT : DINH VU POLYESTER PLANT PROJECT

LOCATION : DVIZ, HAI PHONG CITY, VIETNAM

OWNER : PVTEX., JSC

Document Class: X

B1 Feb. 22, 2010 Issued For Design Y. N. Kim J. S. Kim B. I. Cho

01 Nov. 20, 2009 Issued For Approval Y. N. Kim J. S. Kim B. I. Cho

REV. DATE DESCRIPTION PREPARED CHECKED APPROVED


Doc. No.Job No.Rev. No.Page

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REVISION LOG

REV. NO. REV. DATE REVISED PAGE REVISION DESCRIPTION

01 Nov. 20, 2009 - Issued for Approval

B1 Feb. 22, 2010 1~24 of 31 Revised “Equipment Tag. and Description”

1, 24 of 31 Added “PFD and UFD drawing No.”

2, 3 of 31 Revised “Process summary”

22 of 31 Added “2.14 Product Drain”



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TABLE OF CONTENTS

1. GENERAL...................................................................................................................1

2. POLYCONDENSATION UNIT.....................................................................................1

3. STAPLE FIBER PRODUCTION UNIT......................................................................26

4 FILAMENT PRODUCTION UNIT..............................................................................30



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1. GENERAL

Polyester Plant will be constructed for Petrovietnam Petrochemical and Textile Fiber Joint Stock Company (PVTEX., JSC) at Dinh Vu Industrial Zone. This Polyester Plant consists of three sections:

- Polycondensation Unit

- Staple Fiber Production Unit

- Filament Production Unit

The primary purpose of the polycondensation unit is to produce a high molecular polymer melt with specific viscosity, i.e. the length of the molecular chain of approx. 100 elements. The polymer melt is distributed to staple fiber production unit, filament production unit and the chipping unit.

Polyethylene terephthalate (PET) is produced from purified terephthalic acid (PTA) and ethylene glycol (EG) as main raw materials in a series of subsequent chemical reactions.

2. POLYCONDENSATION UNIT

For an overview of the unit, reference is made to the following Process Flow Diagrams:

- 09035-11-PFD-PR001 PFD for PTA feeding, storage and transport

- 09035-11-PFD-PR101 PFD for PTA Conveying & Storage

- 09035-15-PFD-PR001 PFD for Catalyst preparation

- 09035-15-PFD-PR002 PFD for Dulling agent preparation

- 09035-18-PFD-PR001 PFD for Raw material mixing

- 09035-20-PFD-PR001 PFD for ESPREE Reactor

- 09035-20-PFD-PR002 PFD for Spray system Postesterification (PE), Prepolycondensation (PP) & DISCAGE (DC)

- 09035-22-PFD-PR001 PFD for DISCAGE Reactor

- 09035-24-PFD-PR001 PFD for Vacuum System Poly

- 09035-26-PFD-PR001 PFD for Melt Distribution

- 09035-30-PFD-PR001 PFD for Chips Production

- 09035-33-PFD-PR101 PFD for PET Chip Conveying & Storage

- 09035-37-PFD-PR001 PFD for Spent EG Collection

- 09035-39-PFD-PR001 PFD for Product Drain / TEG Handling

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- 09035-61-UFD-PR001 UFD for HTM Storage, Filling, Vent and Drain

- 09035-61-UFD-PR002 UFD for HTM System : HTM Distribution Plant

- 09035-61-UFD-PR003 UFD for HTM System : HTM Heating Plant Part A

- 09035-61-UFD-PR004 UFD for HTM System : HTM Heating Plant Part B

- 09035-80-PFD-PR001 PFD for MEG Storage

- 09035-93-PFD-PR001 PFD for Filter Cleaning

2.1 PTA FEEDING, STORAGE AND TRANSPORT

Refer to PFD Document No.: 09035-11-PFD-PR001 / 09035-11-PFD-PR101

2.1.1 Basic Objective

PTA is supplied in big bags and conveyed by a pneumatic conveying system to the PTA storage silo 11S58. Closed circulation loop is applied using nitrogen as conveying media.

2.1.2 Major Equipment

11U01 PTA PNEUMATIC CONVEYOR

transport section, for conveying of PTA to the PTA storage silo

11UB11A/B PTA TRANSFER BLOWERS

11UB12A/C VENT BLOWER

11UD11 NITROGEN RECEIVE DRUM

11UE11 PTA TRANSFER BLOWERS DISCHARGE COOLER

11UF11A/C VENT FILTERS

for feeding station

11UF12 DUST FILTER

11UF13A/B NITROGEN LINE FILTER

11UV11A/C PTA TRANSFER HOISTS

for big bag handling

11US11A/C PTA FEEDING HOPPERS

to receive PTA from big bags

INDUSTRIAL VACUUM CLEANER

for cleaning of big bags

11UQ11A/C PTA ROTARY FEEDERS

11S58 PTA STORAGE SILO

for storage of PTA

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2.1.3 Process Summary

Unloading from big bags

PTA big bags are transported from the storage area near to the feeding stations by forklift and lifted by bag lifting device. Three PTA feeding hopper are provided equipped with two nozzles for simultaneous emptying of PTA big bags.

PTA conveying

The PTA is conveyed to the storage silo 11S58 by means of PTA pneumatic conveyor.

Closed circulation loop is applied and nitrogen is used as conveying media to prevent dust explosion by minimizing oxygen in the storage silo and conveying pipes.

A dust filter is provided at the storage silo to remove PTA dust before the nitrogen returns to the nitrogen circuit.

Nitrogen makeup and venting system is provided to maintain the circuit pressure constant, and nitrogen pulsator is provided to remove PTA dust from the dust filter.

2.2 EG STORAGE AND TRANSPORT

Refer to PFD Document No.: 09035-80-PFD-PR001


To store Ethylene Glycol (EG) and to maintain a supply of EG to the polyester plant.


80P01A/B EG TRANSFER PUMPS

for feeding EG to the polyester plant

80S01 EG STORAGE TANK

for storage of EG


Ethylene glycol (EG) is imported by ship and is transferred through the import pipeline into the EG storage tank. EG import line is about 2km from liquid jetty to polyester plant battery limit. From there the glycol is transferred by EG transfer pump to various consumers in the production building.

2.3 CATALYST PREPARATION

Refer to PFD No.: 09035-15-PFD-PR001


To prepare batches of catalyst solution in ethylene glycol (EG) and to store them ready for use in the process.

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15A11 AGITATOR CPC

for stirring / dissolving of catalyst powder

15D11 CPC PREPARATION VESSEL

for preparing catalyst solution in EG

15D12 CPC STORAGE VESSEL

for storing the prepared catalyst solution

15E14 HTM COOLER

15F12A/B CPC FILTERS

15P12A/B CPC PUMPS

15P14 SECONDARY HTM PUMP

15Q10 ADDITIVE SCALE

for weighing additives

15Q11 BAG OPENING / SUCTION SYSTEM

for manual opening and emptying of catalyst bags

* CPC Catalyst Solution


The batch size is chosen to match the production requirement and shall be basically in the range of one day’s consumption. The solution storage capacity is a minimum of 2 days of production in the storage vessel.

Depending on the type of catalyst, the batch is prepared at a higher concentration, heated up to dissolve the catalyst, then EG is added to reach the final concentration. Afterwards the solution is cooled down.

The selected quantity of EG at ambient temperature is filled into the CPC preparation vessel 15D11 by a preset flow counter in the main EG line. The required amount of Antimony Trioxide (Sb2O3) powder, Antimony Triacetate (SbAc3, Sb(CH3COO)3) or Antimony Triglycolate (Sb2EG3, Sb2(C2H4O2)3) is accurately weighed on the additive scale and added into the preparation vessel.

- If Antimony Trioxide (Sb2O3) powder is used as a catalyst, the agitator is started after EG dosing and the solution is heated up to 180°C in order to form antimony glycolate by adjusting the HTM circulation to approx. 200°C (180°C at the end). When all Sb2O3 is completely dissolved (sample solution colourless usually within 2 hours), the HTM heating is stopped and further EG is added to reach the final concentration. Afterwards the catalyst solution is cooled down to approx. 85 °C by adjusting the HTM circulation to approx. 75°C (85°C at the end). For cooling down, the HTM circulation is passed through the air cooler 15E14.

- If Antimony Triglycolate (Sb2EG3, Sb2(C2H4O2)3) is used as catalyst, the agitator is started and the solution is heated up to 120°C by adjusting the HTM circulation to approx. 150°C (120°C at the end). When all Sb2EG3 is completely dissolved (sample solution colorless usually within 1 hour), the HTM heating is stopped and

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further EG is added to reach the final concentration. Afterwards the catalyst solution is cooled down to approx. 85°C by adjusting the HTM circulation to approx. 75°C (85°C at the end). For cooling down, the HTM circulation is passed through the air cooler 15E14.

- If Antimony Triacetate (SbAc3, Sb(CH3COO)3) is used as catalyst, the agitator is started and the solution is dissolved at ambient temperature. When all SbAc3 is completely dissolved (sample solution colorless usually within 1 hour), further EG is added to reach the final concentration.

A sample of each batch is taken for concentration analysis. When the test result is okay, the batch is drained into the CPC storage vessel 15D12.

The main stream of the CPC solution is circulated continuously by the CPC pump 15P12. Only a part stream is filtered through the CPC filter 15F12 in order to remove fine undissolved particles before the catalyst is dosed together with the main EG from the EG mixing tank into the paste mixing vessel. The amount of catalyst solution fed to the process is controlled by a flow controller.

The preparation and the storage vessel (connected in series) are blanketed with nitrogen in order to prevent entering of humidity and to assist the removal of byproducts. The preparation vessel is connected with the process vent system to aspirate the blanketing nitrogen together with vapor of water, EG and other low boiling products.

2.4 DULLING AGENT PREPARATION



TiO2 is suspended in EG at ambient temperature. After dilution and separation of oversized particles, the suspension is diluted with EG to the final dosing concentration and transferred into the TiO2 storage vessel ready for use in the process.


15A71 AGITATOR FOR TIO PREPARATION VESSEL 15D71

for stirring / dispersing of TiO2 slurry

15A72A/B AGITATOR FOR TIO DILUTION VESSELS 15D72A/B

for stirring / dilution of TiO2 slurry

15A75 AGITATOR FOR TIO ADJUSTING VESSEL 15D75

for stirring / adjusting of TiO2 slurry

15A77 AGITATOR FOR TIO STORAGE VESSEL 15D77

for stirring / keeping TiO2 slurry in motion

15A81 AGITATOR FOR TIO SEDIMENT VESSEL 1 15D81

for stirring TiO2 slurry

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15A83 AGITATOR FOR TIO SEDIMENT VESSEL 2 15D83

for stirring TiO2 slurry

15D71 TIO PREPARATION VESSEL

for mixing TiO2 and EG

15D72A/B TIO DILUTION VESSELS

for dilution / resting of TiO2 slurry

15D75 TIO ADJUSTING VESSEL

for adjusting of the final slurry concentration

15D77 TIO STORAGE VESSEL

for final TiO2 slurry buffering

15D81 TIO SEDIMENT VESSEL 1

for collecting coarse TiO2 particles peeled from centrifuge

15D83 TIO SEDIMENT VESSEL 2

for collecting TiO2 slurry from dispersion device

15F77A/B TIO FILTERS

for final filtration of TiO2 suspension

15M74 TIO CENTRIFUGE

for separation of coarse TiO2 particles (agglomerates)

15M82 DISPERSION DEVICE

for dispersing TiO2 particles (agglomerates)

15P74 CENTRIFUGE FEED PUMP

for feeding TiO2 slurry into the centrifuge

15P77A/B TIO DOSING PUMPS

for feeding TiO2 slurry to the esterification reactor

15P82 SEDIMENT FEED PUMP

for feeding TiO2 slurry through the dispersion device

15Q70 BAG LIFTING DEVICE

for lifting and handling of TiO2 big bags

15Q71 TIO FEEDER

for feeding TiO2 powder into the preparation vessel

15V71 BAG OPENING SYSTEM

for emptying TiO2 big bags


The batch size is chosen to match the 1 day production requirements. The

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suspension storage capacity is approximately 2 days of production in the storage vessel. In this way it can be assured that in case of a disturbance the production is not influenced.

The premix of approx. 50 wt-% EG and 50 wt-% TiO2 is prepared in the TIO preparation vessel 15D71. The selected quantity of EG is measured and filled into the preparation vessel 15D71. Afterwards the correct amount of TiO2 is feed from the bag opening system 15V71 through the TIO feeder 15Q71 into the preparation vessel. A homogenous suspension is achieved by intensive mixing with the agitator 15A71.

The 50 wt-% TiO2 suspension is then drained from the preparation vessel 15D71 into the TIO dilution vessels 15D72A/B where more EG is added to obtain a suspension of approx. 18 wt-%. To increase the capacity flexibility and to keep a minimum retention time, two dilution vessels 15D72 are installed.

After a retention time of at least 10 - 12 hours, the suspension is transferred by the centrifuge feed pump 15P74 through the TIO centrifuge 15M74 where oversized particles, agglomerates, are separated from the slurry. The slurry itself is collected in the TIO adjusting vessel 15D75. When the whole TiO2 batch has passed the centrifuge 15M74 a sample is taken to determine the actual TiO2 concentration.

EG is added into the adjusting vessel 15D75 to obtain the final TiO2 concentration of 15 wt-%. Afterwards a sample is taken again and analyzed in the chemical laboratory before the batch is drained into the storage vessel 15D77. In order to check the centrifuge efficiency the 1 µm filter test has to be carried out.

The oversized particles (sediment) which are separated from the slurry in the centrifuge (approx. 3 – 5% of the TiO2 will be separated) are collected in the sediment vessel 1 (15D81). This vessel is equipped with an agitator to prevent sedimentation of the agglomerates.

The collected sediment from the centrifuge has to pass another dispersion step. Therefore it is pumped by the sediment feed pump 15P82 through the dispersion device 15M82 where the TiO2 agglomerates are crushed and dispersed before being collected in the TIO intermediate vessel 2 (15D83), ready for reuse in the next TiO2

preparation batch. To prevent sedimentation the sediment vessel 2 is equipped with an agitator 15A83.

In order to minimize the electrostatic charge, the “crushed” suspension must rest in the sediment vessel 2 (15D83) for at least 4 hours before it is transferred into 15D71 to prepare the next TiO2 batch. The slow-moving agitator 15A83 prevents sedimentation.

Before the content of the sediment vessel 2 (15D83) is drained into the preparation vessel 15D71, its concentration has to be determined in the chemical laboratory in order to re-adjust the EG concentration in the next premix batch properly.

2.5 RAW MATERIAL MIXING



- To meter and to feed PTA and EG in a defined ratio into the paste mixing vessel

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for paste preparation.

- To prepare a homogenous paste.

- To feed the paste to the lower part of the ESPREE reactor (Esterification) in a metered stream.


13F26 EG FILTER

for fine filtration of virgin EG

18A13 AGITATOR DRIVE (PASTE MIX.)

to paste mixing vessel

18D13 PASTE MIXING VESSEL

to prepare and homogenise the paste

18S16 EG MIXING TANK

for homogenisation of virgin and recycled EG

18E16 EG COOLER

to cool down recycled EG

18P13A/B PASTE PUMPS

for metering and feeding paste to esterification

18P16A/B EG MIXING PUMPS

for homogenisation and feeding of EG

18Q13 PTA FEEDER

screw feeder for feeding PTA from storage silo

18Q17 PTA DOSING BALANCE

for exact dosing of PTA into paste mixer


PTA is dosed from the PTA storage silo 11S58 into the paste mixing vessel using a speed controlled screw feeder and a mass flow meter.

Virgin EG is pumped from the EG storage area via EG filter 13F26 to the plant. EG from hotwells 20D33 and 22D43 are collected in the EGS drain tank 37S90 and routed into the EG mixing tank 18S16, in which the liquid is intensively mixed with recycled EG from the process column 20T12. The temperature in the EG mixing tank 18S16 is kept at max. 70°C.

The main EG stream, coming from the EG mixing tank 18S16 is mixed with the metered catalyst solution using high accurate mass flow meter control and with a controlled partial stream of the recycled EG from process column 20T12. The stream is metered and controlled by a mass flow meter and fed into the paste mixing vessel 18D13.

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The partial stream of recycled EG from the process column 20T12 is used to control the temperature of the paste.

All components are well blended and intermixed in the paste mixer by an agitator of special design with the target to form a homogeneous paste, having a molar ratio of approx. 1.5, which easily can be transferred to the bottom part of the ESPREE reactor by volumetric pumps.

To prevent the formation of PTA dust and thus entering into the process vent system, the paste mixer is equipped with a dome containing two EG spray nozzles one on top of the other. The spray EG coming from the EG tank farm is of ambient temperature. This will increase the efficiency of acetaldehyde removal.

The connection to the process vent system on top of the dome generates a slight vacuum to aspirate the system.

The paste is continuously metered and fed into the ESPREE reactor by two speed controlled paste pumps 18P13A/B which are normally running simultaneously, however one pump can handle the full plant capacity.

A mass flow meter is used to measure continuously the paste flow rate and the paste density. The density is proportional to the molar ratio of EG and PTA. The density signal is recorded for easier adjustment of the EG feed controller to maintain a high accuracy of the feed mole ratio, which is important for high process stability.

2.6 ESPREE REACTOR



- To produce diglycolterephthalate (DGT) by a non-catalysed direct esterification between terephthalic acid (PTA) and ethylene glycol (EG).

- To separate the water produced in the esterification process.

- To remove and recover the excess EG (an excess is necessary to promote the reaction) for reuse.

- To remove some of the byproducts from the reaction.


20E10 REBOILER TO ESPREE

external heat exchanger for esterification

20E12 DISTILLATE CONDENSER

for condensing the reaction water

20E13 ECONOMIZER

for preheating EG before entering into process column

20E15 HTM EVAPORATOR (ES)

to heat the bottom of the ESPREE reactor and reboiler of process column 20T12



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20P11A/B MONOMER PUMPS

to transfer monomer from esterification to postesterification

20P12A/B REBOILER PUMPS

for feeding EG from process column reboiler back to reactor 20R10 and to EG mixing tank 18S16

20R10 ESPREE REACTOR

multi stage reactor for

- esterification reaction (ES) of PTA/EG paste

- postesterification (PE)

- prepolycondensation (PP)

20T12 PROCESS COLUMN

for rectification / separation of EG/water vapor

20V10 VACUUM PIPE (PP)

to lead vapor into spray condenser

20RZ10 EG / CPC FEEDING STATION

to mix EG and/or CPC with monomer


The esterification reaction takes place in several stages:

- the first step is done in esterification (bottom part of 20R10, conversion rate of 88% - 92%)

- the next three stages are installed cascade-wise in postesterification (top part of 20R10, conversion rate up to 98%)

During the esterification reaction, polymer chains already begin to form. Further polycondensation and the remaining esterification take place in polycondensation.

The paste including additives is continuously supplied from paste mixing vessel 18D13 by the paste pumps 18P13A/B at a temperature of approx. 65°C into esterification section of the tower reactor 20R10.

Before the paste enters the external tube bundle heat exchanger 20E10, recovered EG from column 20T12 and dulling agent slurry (TiO2) is added to increase the total (inner) mole ratio to 1.75 - 1.80 and to compensate the evaporation loss of EG in esterification. The quantity of recovered EG fed into the paste flow is controlled by a flow control loop. Reboiler pump 20P12 feeds the EG from the bottom of column 20T12 in a part stream back to esterification in order to maintain the inner mole ratio. The level in the process column reboiler 20T12 is controlled by feeding the excess EG back into the EG mixing tank 18S16.

TiO2 slurry enters together with the recovered EG from the column into the paste line below the external heat exchanger. In this way a homogeneous distribution of TiO2 in the monomer is ensured. The TiO2 slurry metering is done by mass flow meter controls, which in turn adjust the speed of the eccentric screw pump.

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The paste, the recovered EG and the TiO2 slurry are fed into the tube side of the heat exchanger 20E10 of the ESPREE reactor through a special inlet nozzle. The paste is immediately mixed with already existing monomer by a static mixer underneath the tube bundle. The natural circulation is generated by the boiling regimes in the heat exchanger. At a operating condition of approx. 255° - 260°C and a pressure of 1.2 - 1.5 barg, the reactants boil vigorously. The conversion rate amounts to approx. 88 - 92% within 60 to 80 minutes reaction time; the degree of polycondensation (DP) increases to approx. 3 units.

As DGT is formed, reaction water is formed which together with portions of EG enters into the process column 20T12. The separated EG is partly (measured and controlled) returned to the esterification to further increase the conversion, whereas the balance EG is sent back to the EG mixing tank for reuse.

The required energy to heat up the paste to reaction condition, to evaporate the formed reaction water and EG and for the reaction itself, is supplied by HTM vapor generated in HTM evaporator 20E15. Depending on the throughput the HTM vapor temperature will vary between 282°C and 290°C.

The monomer from esterification is transferred by gear pumps 20P11A/B from bottom to the top of the tower reactor. For process safety two parallel operated gear pumps are running, each with 50% of the load. In case of a failure, the other gear pump is capable to take care for the full load.

Additional EG to adjust the total mole ratio or alternatively to add catalyst solution is fed into the monomer line. In order to ensure a sufficient mixing of the additional added EG or catalyst solution with the monomer and to obtain a homogeneous fluid, a static mixer 20RZ10 is provided.

The discharge pressure of monomer pumps 20P11A/B is controlled by a pneumatic butterfly valve located at the monomer inlet of the top (first) cascade of postesterification.

Together with reaction water also a part of the EG vapor leaves the esterification. The EG/water mixture is rectified in column 20T12. The water vapor from the top of the column is under pressure (saturated vapor) and is partly used as motive steam for vacuum unit. The excess steam is condensed in distillate condenser 20E12 and the condensed water collected in seal vessel (vacuum) 24D53. The motive steam for the vacuum unit is condensed in the first / final vacuum condensers 24E51/53A/B and collected in seal vessel (vacuum) 24D53 as well.

The water collected in the seal vessel (vacuum) 24D53 is fed through the stripper column 24T61 in order to remove low boiling products such as aldehyde. A part stream is pumped back as reflux to the process column 20T12 by reflux pumps 24P61A/B through reflux flow control, whereas the excess water leaves the stripper column via its overflow.

The postesterification section is divided in 3 cascades incorporating heating coil modules. This installation enhances the evolution and removal of water as well as a uniform residence time distribution. At a total residence time of 50 - 60 minutes, the conversion rate amounts to approx. 98%. The DP will increase to 5 - 6 units. The reaction in postesterification runs under vacuum conditions. The required evaporation and reaction heat is supplied by HTM evaporator 22E25. Depending on the product throughput, the HTM vapor temperature will vary between 290°C and 295°C.

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The second and the third cascade chamber is equipped with injection lances, through which additive solution as an alternative can be fed in.

Vapor, consisting mainly of EG and reaction water, leaves postesterification via the vapor line. It is lead to the spray condenser 20E23 where the vapor is condensed directly by injected spray EG. Non condensables such as acetaldehyde or nitrogen are sucked off by the vacuum system. The spray EG is circulated by spray EG pumps 20P23A/B via the EG coolers 20E24A/B to the spray condenser 20E23. The excess of the EG/water mixture is metered and fed to process column 20T12 for separation.

After leaving postesterification, the monomer is transferred by gravity into the flasher of prepolycondensation. The monomer flow rate is controlled by a level control valve, which receives its setpoint from a level controller at the collector of the prepolycondensation. The prepolycondensation reaction takes place in the following reaction stages:

- flasher

- falling film evaporators

Prepolycondensation of the ESPREE reactor consists of two flasher cascades and two falling film evaporators. In the first flasher cascade the pressure is further reduced and the product overflows through the center pipe into the second flasher camber. The product is evenly distributed and overflows into the falling film cascades. The falling film cascades are equipped with plenty of tubes of a special design. The surface area is increased and thus enhances the polymerization degree by removing of EG/water vapor.

At the end of the prepolycondensation the prepolymer is collected in the bottom, which is used as buffer for prepolymer pumps 22P21A/B.

The prepolycondensation is operated at 5 to 8 mbara and 278° to 282°C. The esterification reaction is finished and the chain length of the prepolymer is increased by polycondensation of ester molecules under cleavage of EG. The vapor leaving prepolycondensation mainly consists of EG which is condensed in spray condenser 20E33 and in mist eliminator 20E36 by injection of cold spray EG (direct condensation).

2.7 DISCAGE REACTOR



To produce polyester polymer having a degree of polycondensation (DP) of approx. 95 - 108, starting from prepolymer received from the ESPREE tower reactor.


22P21A/B PREPOLYMER PUMPS

to transfer product from ESPREE reactor to DISCAGE reactor

22A20 AGITATOR DRIVE (DC)

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22E25 HTM EVAPORATOR (DC)

22P22A/B POLYMER DISCHARGE PUMPS

to discharge melt from DISCAGE reactor

22R20 DISCAGE REACTOR

for polycondensation of product up to DP 108

22V20 VACUUM PIPE (DC)

to lead vapor into spray condenser


The final polycondensation reaction is carried out under fine vacuum. The temperature is higher and the pressure is lower than in the prepoly-condensation stage. To prevent variations in the finished product, the throughput of polycondensation is kept as steady as possible. To achieve this, the level of the DISCAGE reactor is controlled by flow control of the product feed into DISCAGE using the speed controlled prepolymer pumps 22P21A/B. The speed setpoint for the prepolymer pump is set by the inlet level controller of the DISCAGE reactor. Normally, two pumps are running simultaneously, however one pump can handle the full capacity.

The specifically designed DISCAGE reactor is a horizontal reactor, which combines various features in order to treat the product gently to finally reach a DP of 95 to 108. The highly increasing viscosity makes it necessary to force the product in a controlled way through the reactor, avoiding dead spots, generating a large surface of product exposed to vacuum and keeping the process conditions at the lowest possible level. The reactor is equipped with a shaftless cage type agitator 22A20, with a variety of discs (blades), rings, stripper rods and baffles to fulfill the requested features. The process temperature (outlet) is kept between 282°C and 285°C.

The DISCAGE reactor is connected to the HTM evaporator 22E25 to provide the required heat energy.

The polymer discharge pumps 22P22A/B builds up the required pressure for the filtration and distribution of the melt to the melt distribution system.

The melt line, downstream of the discharge pump, is equipped with an online viscosimeter 26M50, which controls the viscosity by setting the corresponding vacuum in the DISCAGE reactor in a range of approx. 1 - 2 mbar.

2.8 SPRAY SYSTEM PE, PP & DC



To separate spent EG from the reaction process and to dispatch it for direct recycling.

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Postesterification (PE)

20D23 EG HOTWELL (PE)

barometric tank for spray EG system

20E23 SPRAY CONDENSER (PE)

for condensation of vapor

20E24A/B EG COOLERS (PE)

for cooling of spray EG from 20E23

20P23A/B SPRAY EG PUMPS (PE)

to circulate spray EG to spray condenser 20E23

Prepolycondensation (PP)

20D33 EG HOTWELL (PP)

barometric tank for spray EG system

20D36 EG SEAL VESSEL

barometric tank for fresh EG spray system

20E33 SPRAY CONDENSER (PP)


20E34A/B EG COOLERS (PP)


20E36 DEMISTER (PP)

for final condensation of vapor

20E37 EG COOLER (DEMISTER PP)


20F33A/B SPRAY EG FILTERS (PP)

20P33A/B SPRAY EG PUMPS (PP)


20P36A/B SPRAY EG PUMPS (DEMISTER PP)

to circulate spray EG to demister 20E36

DISCAGE (DC)

22D43 EG HOTWELL (DC)

barometric tank for spray glycol system

22E43 SPRAY CONDENSER (DC)


22E44A/B EG COOLERS (DC)

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22E46 DEMISTER (DC)

for final condensation of vapor

22E47 EG COOLER (DEMISTER DC)


22F43A/B SPRAY EG FILTERS (DC)

22P43A/B SPRAY EG PUMPS (DC)


22P46A/B SPRAY EG PUMPS (DEMISTER DC)

to circulate spray EG to demister 22E46


The volatile vapor from 20R10 postesterification section is condensed in a single spray condenser.

The volatile vapor from 20R10 prepolycondensation section and DISCAGE reactor are condensed in two spray condenser systems. For separation of mists, oligomers and low boiling components a second large size spray condenser (demister) is provided in each system, before the gases reach the vacuum aggregate.

The systems of spray condensers are described in the following table:

* common tank (internally divided) for both final spray condenser (demister) systems

To enhance the efficiency of the fresh EG system (20D36) the total amount of virgin EG, needed for paste mixing, is routed through the spray EG system and sent back to EG mixing tank. In this way the oligomers removed from the process and collected in the hotwells are diluted continuously.

Virgin EG is fed to the demisters EG circuits of prepoly and DISCAGE reactor in a defined ratio (approx. 40% / 60%). The sum of both EG feeds is controlled by the

20R10 Postester 20R10 Prepoly 22R20 DISCAGE

Stage first - first final first final

Condenser 20E23 - 20E33 20E36 22E43 22E46

Hotwell 20D23 - 20D33 20D36* 22D43 20D36 *

Pump 20P23A/B - 20P33A/B 20P36A/B 22P43A/B 22P46A/B

Filter - - 20F33A/B - 22F43A/B -

Cooler 20E24A/B - 20E34A/B 20E37 22E44A/B 22E47

Medium Spent EG - Spent EG Fresh EG Spent EG Fresh EG

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level control of the EG mixing tank. The excess EG overflows from EG seal vessel 20D36 (prepoly chamber) to EG hotwell (PP) 20D33 and from there via overflow to EGS drain tank 37S90. The excess EG from EG seal vessel 20D36 (DISCAGE chamber) overflows to EG hotwell (DC) 22D43 and from there to EGS drain tank 37S90 as well.

A fixed amount of spent EG from the EG hotwell (PE) 20D23 is sent through the economizer 20E13 to the process column 20T12 in order to reduce the water content in the EG. The economizer heats up the spent EG to approx. 150°C. This helps to avoid a blockage of the internal column packing bed with oligomers.

The level of EG hotwell (PE) 20D23 is kept constant by a control valve in the feed line from 20P33A/B.

Spent EG from the process, which overflows from both EG hotwells (PP and DC) are collected in the drain tank 37S90 and sent direct to the EG mixing tank 18S16 using pump 37P91.

2.9 SPENT EG COLLECTION



To collect spent EG in the drain tank for further treatment or to transfer the spent EG in a storage tank.


37P90 EGS TRANSFER PUMP

to transfer spent EG to process column or collecting tank

37P91 EGS FEED PUMP

to transfer spent EG to the EG mixing tank

37P92 EGS RETURN PUMP

to transfer the spent EG from the storage back to the drain tank

37S90 EGS DRAIN TANK

for collecting overflow EG from the hotwells (PP + DC)

for collecting EG from various drain points such as plate heat

exchangers, pumps, EG samples etc.

37S92 EGS COLLECTING TANK

for collecting spent EG during abnormal situations


The EGS drain tank 37D90 is divided in 2 chambers. One chamber serves as a collecting compartment for the overflow EG from the hotwells. The other chamber is a common drain compartment for the whole plant.

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Virgin EG and spent EG from the prepoly reaction are combined in the EG hotwell (PP) and overflows in the collecting compartment of the EGS drain tank 37S90.

In the same way, virgin and spent EG from the polymerisation reaction are combined in the EG hotwell (DC) and overflows into the same collecting compartment of the drain tank 37S90. The collected EGS is sent direct to the EG mixing tank 18S16 using pump 37P91.

EG and oligomer residues from cleaning plate heat exchangers, EG sample disposal, pump draining, hotwell draining or EG overflow during abnormal drain operations are collected in the second compartment, from where the liquid can be routed by transfer pump 37P90 to the process column 20T12 for recycling or to the EGS collecting tank 37S92 for temporary storage. The collecting tank 37S92 is used only during start-up and / or abnormal arising situations. From the collecting tank 37S92 the EGS can be transferred back into the collecting compartment of the drain tank.

2.10 VACUUM SYSTEM POLY



To generate vacuum required by the polycondensation reaction in the ESPREE reactor 20R10 and DISCAGE reactor 22R20 by means of a steam ejector system using process steam, generated by the esterification reaction in the ester reactor.

To collect all reaction water of the process and all the process vent stream gases.

To strip-out the majority of the low boiling hydrocarbons (HC’s) from the waste water, for its elimination together with the process vent stream gases, by combustion in the HTM plant.


24B61A/B BLOWERS (STRIPPER)

to supply ambient air and process vents to the stripper column

24D53 SEAL POT (VACUUM)

to collect all condensed process reaction water and for barometric sealing of the vacuum system

24E51A/B FIRST CONDENSERS

1 stage condenser for booster group to condense process vapor and motive steam

24E53A/B FINAL CONDENSERS

3 stage condenser for vent group to condense process vapor and motive steam

24E61 OFF GAS HEATER

to reheat gas from the stripper to avoid condensation

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24J36A/B VACUUM AGGREGATES

/24J46A/B consisting of vacuum jet 24J36, 24J46/47 and 24J51/52/53

/24J47A/B multi stage vacuum unit to generate the required vacuum

/24J51A/B in the postesterification, prepoly and DISCAGE reactor

/24J52A/B

/24J53A/B

24P53A/B STRIPPER FEED PUMPS

to feed process water to the stripper column

24P61A/B REFLUX PUMPS

to feed the process water as reflux to the process column

24T61 STRIPPER COLUMN

to eliminate low boilers from process water by a counter current process flow


The vacuum aggregates consist of two groups.

Group one is the compression group and consists of 1 heated booster ejectors (24J36A/B) for 20R10 prepolycondensation and 2 heated booster ejectors (24J46A/B and 24J47A/B) for the DISCAGE reactor and a common surface condensers (24E51A/B).

Group two is the vent group and consists of three ejector stages (24J51A/B / 24J52A/B / 24J53A/B) combined with a three stage surface condensers (24E53A/B).

The vacuum in postesterification section is generated by sucking the non condensable reaction vapor (after condensing in spray condenser 20E23) between second and third stage of the vent group into the surface condensers 24E53A/B.

The process vapor and motive steam from the booster ejectors are condensed in the common condensers 24E51A/B. The motive steam from the vent group ejectors are condensed in the condensers 24E53A/B, which is internally divided in three sections. WCL runs through both surface condensers in series.

The condensed vapor and motive steam together with the remaining process reaction water are collected in the seal vessel 24D53.

The water pumps 24P53A/B feeds the process water to the stripper column 24T61 where it is sprayed on a packing bed. Process vents are collected from various off-gas points in the plant and blown together with fresh air from the bottom of the stripper column to top in a counter current stream through this packing bed by means of blowers 24B61A/B. A considerably lower COD value in the process water is obtained. The air/off-gas mixture is then sent through the off gas heater 24E61 to the HTM burner for combustion. In case of low load or purging of one HTM burner with fresh air, the off gas is sent to open atmosphere (usually only for a very short time) via a control-butterfly valve.

The reflux pumps 24P61A/B feeds the stripped process water to the process column

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20T12, where it is used as column reflux. The stripped excess process water leaves the stripper sump to the waste water treatment plant, where it is neutralized in the collection basin.

2.11 MELT DISTRIBUTION



To filter polymer melt and to distribute the melt to the chipping unit.


26M50 VISCOSIMETER

for continuous online measurement of viscosity

26F51 POLYMER NONSTOP FILTER

for uninterrupted polymer filtration

26Q51 FILTER LIFTING DEVICE

for handling the melt filter inserts

26YP50 MELT TRANSFER PIPE

to distribute the melt to the chipping unit

2.11.3 Process SummaryThe melt is discharged from the DISCAGE by a specially designed gear pump, the polymer discharge pumps 22P22A/B, which supplies sufficient pressure to feed the melt through the polymer nonstop filter 26F51. The polymer melt is diverted by a special melt valve to be fed to the following consumers:

- Direct fiber spinning line- Direct filament spinning line- Pelletizer unit

The polymer nonstop filter 26F51 is a twin type, high pressure polymer filter allowing uninterrupted filter change over. The melt filter has an incorporated hydrolysis cleaning system, for “in-situ” cleaning of the filter candles. The product lines, filter and die heads are jacketed and heated by liquid HTM (HSB system).

The melt line downstream the discharge pump is equipped with an online viscosimeter 26M50, which controls the viscosity by setting the corres-ponding vacuum in the DISCAGE reactor in a range of approx. 0.8 - 2 mbar.

The polymer melt is diverted by a special melt valve to a direct filament spinning line, direct staple fiber line and to a chipping unit 30M11.

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2.12 CHIPS PRODUCTION



- To convert molten polymer into pellets (chip)

- To transport and store the chip in readiness for dispatch

- To bag the chip into big-bags


30B12 VENT BLOWER

for aspiration the air from the pre-dryer

30D15 PROCESS WATER TANK

for storage chipping water used for the chips cutter circuit

30P15A/B PROCESS WATER PUMPS

for circulation of process water

30E15A/B PROCESS WATER COOLERS

to cool down the process water

30F15 PROCESS WATER FILTER

for filtration the process water

30H11 EXTRUSION HEAD

30M11 UNDERWATER STRAND GRANULATOR

consisting of

- strand guide and cooling section with starting device

- cutting machine (cutter head)

- process water measuring and distribution system

- quench line for chip cooling with separator and chip collecting basket

30M12 PRE-DRYER

for chips dewatering

30M13 CHIP SCREEN

to remove oversized chip


One under water strand granulator, pre-dryer and chip screen is provided. The process water circulation unit supplies water to the pelletizer unit.

Molten polymer from the DISCAGE reactor, discharged by means of discharge pumps 22P22A/B is passed through polymer nonstop filter 26F51, fed to the

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extrusion head 30H11 and finally pressed through the spinneret. Strands of polymer emerging from the spinneret are cooled by water in the strand guide section, which guides the strands into the cutting head. Water is sprayed onto the strands by spray nozzles for uniform cooling.

Feed rolls on the cutting head deliver the strands to the rotary cutter which cuts them into cylindrical chip. A stream of conveying water further cools the chip preventing them from sticking together during passing the glass transition temperature.

The process water i.e. overflow water, spray water and conveying water is provided by a closed recirculation system containing demineralized water. The system consists of a process water filter 30F15, a process water tank 30D15, a process water circulation pumps 30P15A/B, and a process water coolers 30E15A/B, which is cooled by cooling water.

The pellet/water mixture flows into the pre-dryer 30M12. Most of the water is removed from the chip by means of screens within the pre-dryer. The chip are internally conveyed by blowing an air stream along meandered channels having perforations, where the water is stripped off. The remaining surface water is evaporated by the residual heat in the chip. An ambient air stream flows in counter-current stream to the chip flow and removes the remaining surface humidity. This air flow also prevents, that humid air from the pre-dryer, dragged by the chip flow, enters the chip intermediate silo 33S10, where the water vapor would condensed.

After the pre-dryer the chips passes the chip screen 30M13 which retains oversized material on a vibrating screen and transfers the chip into the chip intermediate silo 33S10.

The process water leaving the pre-dryer is guided over a process water filter (band filter type) and collected in the process water tank 30D15. The non-woven fabric removes fine cutting dust which otherwise would accumulate in the process water circuit.

2.13 CHIPS STORAGE AND BAGGING



To convey chips to chip storage silos or to the off-spec silo for chips bagging


33Q10 PET CHIP CONVEYOR

33QB01A/BCHIP TRANSFER BLOWERS

to transport chip from intermediate silo to storage silos

33QF01 BAG FILTER

33QQ01 PET CHIP ROTARY FEEDER

to transport chip from intermediate silo to storage silos

33Q46 CHIP PACKING UNIT

for packing chip from storage silo to big bags

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33S10 CHIP INTERMEDIATE SILO

to buffer and to feed chip to transport system

33S11 CHIP STORAGE SILO

33S51 CHIP OFF-SPEC SILO


The pellets coming from the chipping unit passes the chip screen 30M13 for separation oversized pellets, pellet string, agglomerates and falls into the chip intermediate silo. This intermediate silo serves as a buffer. A small portion of air stream from the chip transfer blower is blown into the intermediate silo. This air stream helps to remove residual chip surface water and prevents condensation and collecting of water at the bottom of the silo. The air leaving the intermediate silo is fed to the pre-dryer to create a counter current air flow to the pellet dryer in order to enhance removal of moisture from the chip surface as well.

The chip transfer blower transfers the chip from intermediate silo into the chip storage silo or if required, temporary into the off-spec silo. The target silo can be selected from the process control system. From the storage silo the chip are filled into big bags using a bagging unit.

2.14 PRODUCT DRAIN



- To drain product from reators

- To fill / distribute TEG for cleaning the raetors

- To collect process vapours from safety relief valve


39D81 TEG RESIDUE VESSEL

for storage of TEG/polymer residues

39D95 BLOW DOWN VESSEL

to receive vapors from safety valve / rupture disks

39P80 TEG BARREL PUMP

to transfer TEG from TEG barrels to reactors and hotwells


In case of an unexpected overpressure in the esterification reactor, the safety relief valve release EG/water vapours into the blow down vessel 39D95. An interlock opens spray water in order to condense the EG/water vapours and nitrogen blanketing in order to avoid the formation of an explosive atmosphere.

Monomer is drained from the esterification reactor through the melt valve 570-032,

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prepolymer through melt valve 570-034 and final polymer drained from the discage reactor through the breeches pipe and / or melt valve 570-054 into the residue pit.During normal plant operation the drain pipes are not heated, because there is no need for keeping the drain lines heated at high temperature all the time. Therefore prior the drain procedure all drain pipes must be heated with primary HTM (HPD).

During the drain procedure, the sprinkler nozzle above the residue pit must be put in operation in order to condense the EG vapours.

If the reactors has to be cleaned with TEG, TEG is filled into the hotwells as well as into the reactors. The temperature is increased in the reactors until TEG starts to boil (approx. 280° - 285°C).After boiling the residue sump product is drained into the TEG residue vessel 39D81.

2.15 FILTER CLEANING



- To clean the melt filter candles from filter unit 26F51

- To check for any defects of the melt filter candles for filter pack disassembly and assembly


93D14A/B BACKFLUSH UNITS

for backflushing of the filter candles with steam

93D16 ACID CLEANING BATH

for dissolving of finest TiO2 particles remaining in the filter mesh

93D17 ALKALI CLEANING BATH

for saponification of remainig polymer residues which have not been completely removed during HYPOX-cleaning

93D18 RINSING BATH

to rinsing the filter candles treated in the acid or alkali cleaning bath

93P16 HAND PUMP

93V11A/B ULTRASONIC CLEANING UNIT

for removal of insoluble solid particles

93V12A/B WORKING TABLES

93V13 FLUSH VESSEL

for final flushing with demineralised water

93V14 BUBBLE POINT TESTING DEVICE

to check the filter candles for mechanical damages

93V15A/B HIGH PRESSURE WATER PUMPS

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93V16 BASKET

93V20 TRANSPORT TROLLEY

93V26 SUCTION HOOD


Before filter cleaning the filter candles are cleaned in the hydrolysis cleaning system (HYPOX) integrated in the filter unit 26F51.

HYPOX cleaing process is based on the hydrolysis at high temperature.

(HYPOX = HYdrolysis, Pyrolysis, OXidation)

The cleaning process consist of a controlled temperature programme. The polymer is drained from the filter housing using nitrogen. Afterwards the filter housing with the filter candles is treated with superheated steam and later with air. In this way the polymer is degraded completely.

After the HYPOX cleaning process, the filter insert is removed from the housing and the single filter candles are dismounted in the filter cleaning workshop.

In a first step each filter candle is treated in the backflush unit 93D14A/B with medium pressure steam for a minimum of 2-5 minutes. Afterwards, the filter candles are treated in the acid cleaning bath 93D16, using 20 wt% nitric acid solution (HNO3) for about 15 minutes. This treatment is necessary to remove/dissolve traces of remaining TiO2 particles from the filter mesh.

After rinsing with demineralised water, the candles are treated in the alkali cleaning bath 93D17 using 30 wt% caustic soda solution (NaOH) for about three hours. In order to accelerate the saponification process, the bath is heated with steam to max. 75°C for approx. 3 hours.

After a further flushing with water, each candle is treated in the ultrasonic cleaning unit 93V11 for at least 20 minutes using detergent in order to remove undissolved particles such as carbonized polymer residues.

After a final cleaning procedure in the flushing unit 93V13 (to clean the candles from detergent) and in the backflush unit, the filter candles are tested for mechanical damages in the bubble point testing device 93V14 using isopropyl alcohol (lower surface tension compared to water).

After the bubble point test, the filter candles are flushed with water to remove the isopropyl alcohol and then dried in the infrared drying oven at a temperature of about 150°C for at least 3 hours.

After cooling down to room temperature, each single filter candle is weight on a balance and their weight is recorded on a data sheet and compared with its original weight. Any difference in weight indicates remaining residues inside the filter candle. If so, the cleaning procedure has to be repeated.

Finally, the filter candles are assembled again, ready to reuse in the melt filter unit.

2.16 HTM HEATING

Refer to UFD Document No.: 09035-61-UFD-PR001~004

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To heat and maintain temperature of polymer melt applications


Later (after receipt of vendor information)


Primary Heat-Transfer-medium (HTM-System)

The primary Heat-Transfer-Medium (HTM-System) is a forced circulation system supplying the polycondensation plant with the required heating energy. The heat transfer medium is circulated by primary HTM pumps and heated in a tubular heater. It transfers its heat, as required, to the various consumers in the esterification and polycondensation. To ensure adequate flow and temperature in the heaters during commissioning or in the event of low heat requirements, a direct connection (by-pass) with a control valve is provided between supply and return line parallel to the consumers.

The entire system is pressurized with nitrogen to prevent vaporization of Heat-Transfer-Medium in the primary system (hazard of cavitation in circulation pumps). The nitrogen connection is provided at the HTM expansion vessel which is connected to the system at the suction side of the primary HTM pumps. A HTM collecting tank is provided for partial or complete draining of the different HTM systems. All heat exchangers (HTM evaporators) can be isolated and drained or filled separately. Filling is accomplished by the HTM refilling pump and the independent filling system.

The HTM collecting tank is connected to the atmosphere via a vent condenser. Hot ascending HTM vapor are condensed in this condenser and returned to the HTM collecting tank, this to avoid HTM losses and air pollution. The tubular heater is a cylindrical unit with refractory lining which will be fired with fuel gas. The flue gas leaves the heater via air preheater (energy recovery) through a stack to the atmosphere.

The heating plant is arranged for open-air installation. Combustion air is partly taken in from the atmosphere by the air ventilator and passes the air preheater to the combustion chamber. This air collects most of the low boiling by-products from esterification and polycondensation reaction. These hydrocarbons shall be burnt in the heating plant for ecological reasons.

Secondary HTM Systems

The secondary systems are connected direct to the primary system by supply and return lines and work as direct injection systems. The supply line, in which a temperature control valve is installed, connects the primary supply to the secondary suction side. Temperature of the secondary system is controlled by mixing of hot HTM from the primary system into the colder secondary systems. The provision of separate expansion vessels is therefore not necessary. The heat transfer medium system is circulated by pumps. The secondary system B (HSB) generally is heating the product lines and its operation of the heating system several auxiliary systems, such as vent systems, drain systems and a filling system, are provided.



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3. STAPLE FIBER PRODUCTION UNIT

3.1 BASIC OBJECTIVE

The supplied melt from the polycondensation unit is directly conveyed via the jacketed melt pipe to the staple fiber production lines. Final product is staple fiber, which is baled in standard bags.

3.2 MAJOR EQUIPMENT


3.3 PROCESS SUMMARY

3.3.1 Melt Conveying System

The melt coming from the melt take-over point located directly behind the polycondensation plant is led through the main polymer melt pipeline to a 3-way valve where the melt is distributed to two polymer melt transfer pipelines (heated by HTM).

Behind the 3-way valves the melt is conveyed by booster pumps and through polymer coolers (heated by HTM, cooled by air) to the 48 spinning position of each line. There the melt will be transferred in a further polymer melt transfer pipeline (heated by HTM) to the melt distribution pipeline.

3.3.2 Melt Distribution and Spinning System

Including melt distribution pipeline, spinning beams, spin packs, spin pumps, quenching, finish application. At each spinning position, the melt throughput can be manually shut off by means of a valve.

- HTM systems for melt pipe & spinning beam

The melted polymer is uniformly distributed in a jacket heated melt distribution pipe system designed in such a way that an equal retention time of the melt for each position is guaranteed.

A HTM system keeps the melt under controlled temperature condition in the manifolds and spinning beams. Liquid HTM is supplied in barrels and the first filling is pumped into the HTM heater. The liquid HTM gets vaporized in the heater. The vapor transfers the heat to the pipe system and spinning beams and provides an absolutely uniform temperature in the heated areas. The condensate returns to the heater in a closed circuit. After heating up with intermediate venting, the system is ready for operation. Two heaters are serving one line. One heater is used for the spinning beams, one heater for the manifold.

- Static mixers



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The static mixers in the pipe system guarantee a uniform temperature profile in the melt, without creating any dead spots in the system. They are located before the distribution of the melt to the three spinning beams and before the distribution of the meld to the two inlets of each spinning beam.

- Spinning beam

In the spinning beam the melt is distributed from the melt inlet to the individual spinning section.

- Spinning pump

The meld throughput of each spin position is accurately maintained by one single driven precision gear pump. This spinning pump pumps the melt through the spin racks, where it is filtered, and then through the spinneret holes, in which the melt is transformed to filaments.

- Spin rack

Consisting of upper part and distribution plate and spinneret, the melt will be filtered by means of metal powder and sieves. The spin packs are mounted from top by a mounting system.

- Quench air duct & quench air unit

The freshly spun filaments then pass through quench air duct where the laminary quench air flow is distributed with regulated velocity and controlled temperature and humidity. The quench air is prepared for the necessary process conditions in the quench air unit. The air-volume is controlled by speed adjustment of the blower fan within the limits of optimal pressure diagram. The individual air-volume per quenching chamber is regulated and adjusted automatically by an air volume control system. The filaments are solidified with a uniform cross-section.

- Spin finish system quench air duct

Passing the quench air duct the filament bundles are guided over finish-oiled guide rings. From the quench air ducts, the filaments are led through the spinning tube down to the fiber draw-off wall.

3.3.3 Draw-off wall and canning system

- Spin finish application

After leaving the spinning tubes, the filament bundles of each position pass through a spin finish nozzle application system for uniform spin finish application.

- Tow threading & plying



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The filaments of each position are then guided by non-driven guide rolls and finally gathered into one combined tow.

- Feed Unit

The combined spun tow from all positions is then pulled by the speed controlled feed roller with 6 rolls to the stationary sunflower wheel and doffed into cans. This system is equipped with an automatic cutting device that cuts the tow during the doffing of the cans.

- Can traversing unit

Both transversing directions of the can are effected by the servomotor driven can traversing unit. The can doffing process is carried out fully automatically. The length of the tow supplied to the can is metered. The shape of the can is square.

3.3.4 Fiber line

- Tow can conveying

The cans are discharged by a fork lift truck to the creel at the fiber line.

- Can Creel

The tows from the cans in the creel are guided to the inlet thread guide to form three uniform tow bands. These bands are then taken over the rollers of the tow guide stand that ensures constant tension before the tow enters the heated immersion bath, receiving the necessary finish oil and a uniform temperature.

- Drawing

The tows from the cans in the creel are guided to the inlet thread guide to form three uniform tow bands. Theses bands are then taken over the rollers of the tow guide stand that ensures constant tension before the tow enters the heated immersion bath, receiving the necessary finish oil and a uniform temperature.

- Heat seating

For high and medium modulus fiber types, the calendar drier is used for heatsetting under tension and high temperature. For high modulus fiber, the material has to be cooled under tension by spraying demineralized water onto the tow between calendar drier and draw stand 4 (also called cooling stand).

- Crimper

Then the three uniform tows are stacked to one uniform tow with the proper width to enter the crimper. Then the tow passes the dancer roller 1 that guarantees a constant tow tension in front of the crimper by controlling the crimper speed. Before



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entering the crimper, the tow passes the steam box where it is heated up.

- Plate belt drier

After crimping, the tow is uniformly dried and cooled under relaxed conditions in the plate belt drier.

- Cutting machine

Leaving the drier, the tow is fed under uniform tension into the cutting machine where the tow is cut into the required staple length. The cutting machine is positioned on top of the baling press and the fiber transport is done by gravity through the fiber distributor to the balers. Baling presses pressure of the nip rolls and the stuffing box.

- Bailing press

After cutting, the fiber is conveyed to the baler to product bales. Baling is two-step process with pre-press & final press.

- Bale transport

The strapped and wrapped bale will be ejected out of the baling press. A fork lift truck will pick-up the bale for transportation.

3.3.5 Spin finish preparation and application system

During the spinning and drawing procedure of synthetic fibers, the fibers must be coated with a liquid several times. Apart from being moisturized, the synthetic yarn is kept supple for the drawing and the yarn is protected against contamination. This liquid is described as a spin finish solution. The production of the spin finish solution is effected in a so called spin finish kitchen in which a spin finish concentrate (powder or paste) is diluted to a working solution.

The process desired concentration of spin finish is achieved in the heated spin finish mixing tank where the high concentrated spin finish solution is diluted with demineralized water to a certain ratio. The total content of homogenous spin finish solution is transferred from the mixing tanks to one of the storage tanks. From here the spin finish solution is fed by means of circulating pumps to different processing points as follows:

- Spin finish application rings in the quench air ducts

- Spin finish nozzles at fiber draw-off wall

- Moisturizing unit

- Draw chest 1

- Spraying device 2

4 FILAMENT PRODUCTION UNIT



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4.1 BASIC OBJECTIVE

The polymer melt from the polycondensation unit is directly transferred to filament production lines. First product is partially oriented yarn (POY) filament, and then POY is transferred to Texturing machines. Final product is Draw textured yarn (DTY) filament.

4.2 MAJOR EQUIPMENT


4.3 PROCESS SUMMARY

4.1.1 POY filament spinning

After leaving the final reactor of Polycondensation unit, the polymer melt is directly transferred and distributed to each spinning line via the polymer distribution system. To assure a homogeneous polymer melt quality for all spinning sections, in front of each distribution, static mixer are installed.

Due to the final arrangement of the production program, the product distribution system will adapted accordingly to give the required flexibility combined with highest product quality and productivity. To adjust the melt temperature to the specific required condition for each product, polymer heat exchangers are installed for each spinning line. For constant melt pressure in front of each spinning pump, booster pumps at specific points are required. The final necessity of polymer heat exchanger as well as booster pumps has to be calculated during project execution according to the requested production program.

When the polymer melt is entering the spinning manifold, it is transferred with the metering spinning pumps to each spin pack. The spinning pumps ensure a high consistency of melt throughput for each spin pack. This is one basic of a very homogeneous production.

Inside the spin pack a homogeneous polymer distribution to the spinneret takes place. The spin pack formation can be adapted to the final product, to ensure the best and reproducible quality of the products.

After leaving the spinneret, the melt is solidified by the quench air system under constant conditions. For the quench air supply, separate units are installed. With this quench air AC-units a constant and adequate air quality regarding temperature and humidity is adjusted.

When the filament yarn is solidified, it passes the spin finish unit, where special oil/water mixtures are added onto the yarn for less friction, reduced static charge as well as high yarn cohesion. The spin finish will be prepared in the spin finish preparation area, according to the final products and down stream processes.

As a connection between the spinning section and the take up section, the so called spinning duct is installed. This spinning duct will protect the yarn against air streams form the surrounding.

While entering the take up section, the yarn is passing the suction and cutting device. In case of yarn break, all yarns are cut and transferred via pipes to a waste



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collecting bin. This suction and cutting device is connected to the yarn detector for each filament yarn near the winder. Behind the suction and cutting device, the filament yarns are passing the godet units.

The Godet units are installed for optimum process reliability and best adjustment possibilities of the overall process in respect to the yarn quality. Finally the yarn is wound up on bobbins by an automatic winding system.

4.1.2 DTY Texturing Process Explanation for PETPolyester is a category of polymers which contains the ester functional group in their main chain, commonly being referred to as polyethylene terephthalate (PET). PET is the main source for production of manmade fibers. The latter implies that polymer melt is directly converted into textile fibers or filaments without the common step of palletizing. It is also called filament yarn.To make use of filament yarn in downstream operation the intermediate has to have certain properties which are being applied during the process of spinning, the intermediate itself is called POY. In the subsequent downstream process the intermediate is given different properties like volume, crimp and elasticity, which result for the final consumer in the desired features like insulation, touch and comfort.This subsequent process is called draw texturing and the final product draw textured yarn (DTY). Hereinafter this process is described.POY is fed via the 1st feed unit and simultaneously drawn by the 2nd feed unit. At the same time twist is being inserted via friction aggregates located between 1st

and 2nd feed unit. The twist moved backward in direction of 1st feed unit into the upper heater and cooling, where the PET is being thermoformed and fixated in its twisted form. To lower the internal stress of the already crimpy yarn and to adjust elasticity and tenacity, a further heat set process between 2nd and 3rd feed unit helps relax the yarn. After the 3rd feed unit the yarn is wounded up in packages suitable for further downstream processes like weaving and knitting.

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