ldpe eloallitasa
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LDPE LDPE TechnologyTechnology20102010
ElEladad: Csernyik Istv: Csernyik Istvnn
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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
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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))
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44
ApplicationApplication
Film65%
Extrusion coating
10%
Other14%
Injection moulding
7%
Blow moulding
4%
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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2020
HyperHyper CompressorCompressor ArrangementArrangement
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2121
HyperHyper CompressorCompressor CylinderCylinder
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2222
ExtruderExtruder ArrangementArrangement
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2323
SingleSingle--screwscrew ExtruderExtruder
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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
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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
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2626
Appendix: Metal GasketAppendix: Metal Gasket
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2727
Appendix: Hyper compressor cylinderAppendix: Hyper compressor cylinder
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2828
Appendix: Appendix: Blown Film ExtrusionBlown Film Extrusion
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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
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