LDPE LDPE TechnologyTechnology20102010

ElEladad: Csernyik Istv: Csernyik Istvnn

22

ContentContent What is LDPEWhat is LDPE ApplicationApplication HistoryHistory Process theoryProcess theory Autoclave processAutoclave process Tubular processTubular process Process stepsProcess steps Process controlProcess control Process safetyProcess safety Key equipmentKey equipment Investment costInvestment cost Cost of productionCost of production

33

What is LDPEWhat is LDPE

LLow ow DDensity ensity PPolyolyEEthylenethylene Typical propertiesTypical properties DensityDensity 0,910,9155--0,930,9355 Melt indexMelt index 0,30,3-->>20 g/10 min (190 C/2,16 20 g/10 min (190 C/2,16

kg)kg) Melting pointMelting point 120 C120 C PolydispersityPolydispersity 5,5 5,5 6 (TVK tubular6 (TVK tubular

ggradesrades))

44

ApplicationApplication

Film65%

Extrusion coating

10%

Other14%

Injection moulding

7%

Blow moulding

4%

55

Application by PropertiesApplication by Properties

0,1

1

10

100

0,915 0,92 0,925 0,93 0,935

EXTRUSION COATING

FILM EXTRUSION

INJECTION MOULDINGEXTRUSION COATING

BLOW MOULDING

M

I

,

g

/

1

0

m

i

n

/

1

9

0

C

Density, kg/dm3

66

HistoryHistory LDPE was discovered by ICI in 1933 LDPE was discovered by ICI in 1933 autoclave autoclave

processprocess inin 19381938 BASF developed the first tubular process during WW IIBASF developed the first tubular process during WW II High variation of autoclave and tubular processes by High variation of autoclave and tubular processes by

different licensorsdifferent licensors Nowadays licences available up to 400 Nowadays licences available up to 400 kt/ykt/y plant plant

capacitycapacity Global consumptionGlobal consumption inin 2009:2009: 1188 million million tt TVK LDPE plantsTVK LDPE plants

1970 1970 -- ICI autoclave process 24 ICI autoclave process 24 kt/ykt/y debottleneckeddebottlenecked to 50 to 50 kt/ykt/y 1991 1991 -- BASF tubular process 60 BASF tubular process 60 kt/ykt/y

77

Process TheoryProcess Theory 11

Free radical reactionFree radical reaction InitiationInitiation

I I

RR

+ R+ RInitiators: typically organicInitiators: typically organic

peroxidesperoxides

PropagationPropagationRR

+ CH+ CH

22

CHCH

2 2 RCHRCH

22

CHCH

22

R(CHR(CH

22

CHCH

22

))

nn--11

CHCH

22

CHCH

22

++

CHCH

22

CHCH

2 2

R(CHR(CH

22

CHCH

22

))

nn

CHCH

22

CHCH

22

TerminationTermination CombinationCombination

RR

xx

++

RR

yy

PP

xx+y+y

DisproportionDisproportioningingRR

xx

++

RR

yy

PP

x x + + PP

yy

88

Process TheoryProcess Theory 22

Other reactionsOther reactions Chain transfer Chain transfer important to control important to control

molecular weightmolecular weight

RRxx

+ CH+ CH22

CHCH22

PPx x + R+ R11

by monomerby monomerRRxx

+ + MMPPxx

+ M+ M

by modifierby modifier Cracking Cracking results in shorter chainsresults in shorter chains

RRxx

PPyy

+ R+ Rxx--yy

99

Process TheoryProcess Theory 33

Branching Branching LDPE characterised by high degree LDPE characterised by high degree of short and long chain branchingof short and long chain branching Short chain branching Short chain branching responsible for densityresponsible for densityIntramolecularIntramolecular

chain transfer and copolymerisation result in chain transfer and copolymerisation result in

short chain branchesshort chain branches

Long chain branchingLong chain branchingIntermolecular chain transfers give long chain branchesIntermolecular chain transfers give long chain branches

CC

HC C

C

C C C C

C C CH

C C C

C C C

1010

LDPE LDPE -- Autoclave ProcessAutoclave Process

Initiators(Peroxides)

Autoclavereactor

Secondarycompressor

Primarycompressor

280 bar250 C

HP separator

Waxseparator

0,5 bar250 C

LP separator

Extruder

Ethylene

Oilseparator

250 bar

1400 bar

170 C

240 C

280 C

BaggingBulk loading

Degassing

1111

AutoclaveAutoclave ReactorReactorAutoclave reactor MK 10

L = 4750 mm d = 18

Thermocouple 1(1st T control)

Thermocouple 2

Thermocouple 4(2nd T control)

Thermocouple 5

Thermocouple 6

Thermocouple 7(control 2nd zone T)

Thermocouple 8

Thermocouple 9(control 3rd zone T)

Thermocouple 10(control 4th zone T)

Thermocouple 3

Top Zone

2nd Zone

3rd Zone

4th Zone

Total 725 l

ethylene

peroxides

1212

LDPE LDPE -- Tubular ProcessTubular Process

Modifier

Fresh Ethylene

Purge

Initiator(Oxygen)

PrimaryCompressor

SecondaryCompressor

Preheater

Precooler

Reaction Zone I

Reaction Zone II

HP Separator

LP Separator

Extruder

HP RecycleLP Recycle

280 bar250 C

0,5 bar250 C

2400-2900 bar

180-310 C

250 bar

BaggingBulk loading

Degassing

1313

Autoclave vs. Tubular ProcessAutoclave vs. Tubular Process

AutoclaveAutoclave Conversion up to 21% Conversion up to 21% --

adiabatic, reaction heat adiabatic, reaction heat removed by reactant onlyremoved by reactant only

13001300--2000 bar operating 2000 bar operating pressurepressure

Higher capacity of hyperHigher capacity of hypercompressorcompressor

Organic peroxide initiators onlyOrganic peroxide initiators only Specialty polymer capability Specialty polymer capability

EVA copolymers over 40% EVA copolymers over 40% vinyl acetatevinyl acetate

Lower reactor capacity Lower reactor capacity 150 150 kt/ykt/y

TubularTubular Conversion up to 36% Conversion up to 36% --

rreaeactionction heat partly removed heat partly removed by coolantby coolant

25002500--3200 bar operating 3200 bar operating pressurepressure

Lower capacity of hyper but Lower capacity of hyper but higher loadhigher load

Cheaper oxygen initiator Cheaper oxygen initiator possiblepossible

Film Film grades with higher claritygrades with higher clarity,,EVA up to 10% vinyl acetateEVA up to 10% vinyl acetate

Reactor capacity up to 400 Reactor capacity up to 400 kt/ykt/y

1414

Process Steps 1Process Steps 1

CompressionCompression Increase make up ethylene Increase make up ethylene

pressure to reaction pressure to reaction pressurepressure

Recycle Recycle unreactedunreacted ethyleneethylene Inject modifier and Inject modifier and

comonomercomonomer ReactionReaction

Injection of initiatorsInjection of initiators Control temperatures for Control temperatures for

required product propertiesrequired product properties One phase reaction One phase reaction two two

phase only at lower phase only at lower pressure and temperaturepressure and temperature

Short residence time Short residence time some minutessome minutes

1515

Process Steps 2Process Steps 2

HP separatorHP separator Separate melt LDPE and Separate melt LDPE and

unreactedunreacted ethyleneethylene LP separatorLP separator

Remove Remove unreactedunreacted ethyleneethylene Feed tank for extruderFeed tank for extruder

HP recycleHP recycle Remove low molecular weight Remove low molecular weight

polymer (wax)polymer (wax) Cool down recycle ethyleneCool down recycle ethylene

LP recycleLP recycle Remove low molecular weight Remove low molecular weight

polymer (wax, oils)polymer (wax, oils) Cool down recycle ethyleneCool down recycle ethylene

1616

Process Steps 3Process Steps 3

ExtrusionExtrusion HomogenizationHomogenization Additive dosingAdditive dosing PelletizingPelletizing

DegassingDegassing Remove residual Remove residual

ethylene (generally ethylene (generally less than 1000 less than 1000 ppmppm) ) from LDPE from LDPE to avoid to avoid explosive gas mixturesexplosive gas mixtures

1717

Melt index (Molecular weight)Melt index (Molecular weight) PP MIMI (M(Mww)) TT MIMI (M(Mww)) [Modifier][Modifier] MIMI (M(Mww))

DensityDensity PP DD TT DD

Pressure range: 1300Pressure range: 1300--3000 bar3000 bar Temperature range: 160Temperature range: 160--310 C310 C

Process ControlProcess Control

1818

Risk of decompositionRisk of decomposition Decomposition: ethylene or polyethylene Decomposition: ethylene or polyethylene decompsdecomps to C and Hto C and H22 High temperature, high pressure, contaminations favour High temperature, high pressure, contaminations favour

decompositiondecomposition

Reactor and HP separator in confined area Reactor and HP separator in confined area generally generally behind concrete wallbehind concrete wall

Interlock system toInterlock system to avoid decomposition andavoid decomposition and protect equipmentprotect equipment

Special metal gaskets at high pressuresSpecial metal gaskets at high pressures Gas detectorsGas detectors Fire fighting systemFire fighting system

Process SafetyProcess Safety

1919

Key EquipmentKey Equipment

CompressorsCompressors Primary compressor (Primary compressor (Booster+PrimaryBooster+Primary))

5 stages5 stages 0,1 bar suction; 250 bar discharge0,1 bar suction; 250 bar discharge

Secondary compressor (Hyper)Secondary compressor (Hyper) Two stagesTwo stages 250 bar suction; 3000 bar discharge250 bar suction; 3000 bar discharge

ExtruderExtruder Hot melt extruder for homogenizationHot melt extruder for homogenization

2020

HyperHyper CompressorCompressor ArrangementArrangement

2121

HyperHyper CompressorCompressor CylinderCylinder

2222

ExtruderExtruder ArrangementArrangement

2323

SingleSingle--screwscrew ExtruderExtruder

2424

Investment costInvestment cost Basis: USGC 2008Q1Basis: USGC 2008Q1

Process Autoclave Autoclave TubularPlant size 135 kt 3x135 kt 400 kt

ISBL 91,7 231,6 130,1OSBL 60,6 142,3 118,4Other project cost 61,2 160,5 125,1Total investment 213,5 534,4 373,6

Specific investment, USD/t 1581 1320 934

million USD

2525

Cost of ProductionCost of Production Basis: USGC 2008Q1Basis: USGC 2008Q1

Autoclave Autoclave Tubular135 kt 3x135 kt 400 kt

USD/tEthylene 1354 1354 1347Catalysts&chemicals 8 8 5Additives 14 14 14Total raw materials 1376 1376 1366

Power 51 51 58Other utilities 9 9 7Steam credit -34Total utilities 60 60 31

Direct cash cost 34 22 14Allocated cash cost 37 27 18Total fixed costs 71 49 32

Total cash cost 1507 1485 1429

80%

85%

90%

95%

100%

135 kt 3x135 kt 400 kt

Autoclave Autoclave Tubular

Total fixed costsTotal utilitiesTotal raw materials

2626

Appendix: Metal GasketAppendix: Metal Gasket

2727

Appendix: Hyper compressor cylinderAppendix: Hyper compressor cylinder

2828

Appendix: Appendix: Blown Film ExtrusionBlown Film Extrusion

2929

Appendix: Appendix: Extrusion CoatingExtrusion Coating

LDPE TechnologyContentWhat is LDPEApplicationApplication by PropertiesHistoryProcess Theory 1Process Theory 2Process Theory 3LDPE - Autoclave ProcessAutoclave ReactorLDPE - Tubular ProcessAutoclave vs. Tubular ProcessProcess Steps 1Process Steps 2Process Steps 3Process ControlProcess SafetyKey EquipmentHyper Compressor ArrangementHyper Compressor CylinderExtruder ArrangementSingle-screw ExtruderInvestment cost Basis: USGC 2008Q1Cost of ProductionBasis: USGC 2008Q1Appendix: Metal GasketAppendix: Hyper compressor cylinderAppendix: Blown Film ExtrusionAppendix: Extrusion Coating