lube base oil
DESCRIPTION
Manufacturing ProcessesTRANSCRIPT
© 2009 - IFP Training
RA HDB - 00014_C_A - Rev. 7 06/04/2009
Refining-Petrochemicals-Chemicals-Engineering
———
LUBE BASE OIL MANUFACTURING PROCESSES
1 - LUBRICANTS..................................................................................................................................1
2 - BASE OILS PROPERTIES.............................................................................................................1
3 - COMPOSITION OF MINERAL BASE OILS ..................................................................................2
4 - LUBE BASE OILS MANUFACTURING .........................................................................................2
APPENDICES
Recommended properties of lube base oils .................................................................................4
Lubricating oil ..................................................................................................................................5
Structure to property relation for hydrocarbons present in lube oil cuts.......................................6
Standard base oil manufacturing processes .................................................................................7
Paraffinic base oil manufacturing scheme - Block flow diagram ..................................................8
Example of obtained product yields in a classic lube base oil refining unit .................................9
Manufacturing of paraffinic lube oils by hydrotreating.................................................................10
Base oil manufacturing - Propane deasphalting..........................................................................11
Base oil manufacturing - Furfural extraction................................................................................12
Base oil manufacturing - Solvent (MEK + Toluene) Dewaxing...................................................13
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1 - LUBRICANTS
Lubricants are made of finished base oils blended with one another and with additives. There are
several types of lubricants:
- engine oils - industrial oils
- metal working fluids - medicinal white oils
- greases
The main purpose of a lubricant is to reduce friction: the reduction of friction is accomplished by
maintaining a film of lubricant between surfaces that are moving with respect to each other, thereby preventing the surfaces from coming into contact and subsequently causing damage.
Besides the reduction of friction, lubricating oils also perform a large number of other functions:
removal of heat, prevention of rust and corrosion, dispersion, sealing. These functions are provided by the base oil, and are enhanced by the use of additives in amounts ranging from 1 to 25% or more.
The main market for additives is the engine oils. The purpose of these additives is to:
- protect metal surfaces
- extend the range of lubricant applicability - extend lubricant file
The Society of Automotive Engineer, USA has established that twelve viscosity grades are suitable
for engine lubricating oils. The 0W, 5W, 10W, 15W, 20W, 25W engine oils refer to a low temperature viscosity while the 20, 30, 40, 50, 60 engine oils refer to a high temperature viscosity.
2 - BASE OILS PROPERTIES (figures 1 and 2)
a - Origin of base oils
The general term lube base oils cover a number of different types of material including vegetable oils,
synthetic oils, mineral oils and re-refined oils. This dossier only covers mineral oils which are produced from the distillation of crude oils.
b - Viscosity
Viscosity is one of the most important properties of a lubricating oil. It is one of the factors responsible
for the formation of lubricating film under both thick and thin film conditions.
Base oils are defined as either light or heavy according to their kinematics viscosity at 40°C. Those having viscosities above 35 cSt at 40°C are described as heavy and those below light. Most refiners
produce three to four grades from which are blended the finished oils.
c - Viscosity index
The viscosity index (VI) is a number characterizing the degree of change in viscosity of an oil within a
given temperature range. A high VI signifies a relatively small change in viscosity with temperature whereas a low VI reflects a large viscosity change with temperature. Calculation of an oil’s viscosity
index requires the determination of kinematic viscosities at 40°C and 100°C.
d - Other properties
Specifications for lubricating oils cover such properties as density, kinematic viscosity at 40 and 100°C,
viscosity index, pour point and flash point. At ambient temperature, almost all lubricating base stocks are liquid with negligible vapor pressure.
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3 - COMPOSITION AND CLASSIFICATION OF MINERAL BASE OILS
a - Composition (Figure 3)
The major types of hydrocarbons present in crude oils are linear paraffins (n-paraffins), branched paraffins (iso-paraffins), cycloparaffins (naphtenes) and aromatics.
Mineral base oils consist of two types: the naphtenic and the paraffinic base oils depending on the
dominant hydrocarbons type present. The paraffinic base oils are the preferred stocks used for engine
oils.
The proportion of the various base oils components determines the characteristics of the base oils.
Viscosity increases with the length of the carbon atom chain.
Most favored crude are paraffinic crude which give good yields of high VI stocks. For certain
applications, naphthenic crudes are selected because they yield stocks with little wax and naturally low pour points.
b - Classification
ATIEL, the Technical Association of the European Lubricants Industry defines 5 base oil groups, of
which 3 are mineral base oils. This classification allows to establish guidelines for interchanging base
oils in lubricants.
Base oil category
Satuates %
Sulfur % m Viscosity Index
Group I < 90 and/or > 0,03 and 80 < 120
Group II 90 0,03 and 80 < 120
Group III 90 0,03 120
The manufacturing of the different groups from crude oil is related to the refining processes which are used.
4 - LUBE BASE OILS MANUFACTURING (figures 4, 5 and 6)
The manufacture of lube base stocks consists of several steps.
a - Vacuum distillation and deasphalting
Vacuumresidue
DAO
Asphalt
VACUUM
D1
D3
D2
Atmosphericresidue
D P
CD
239
7 B
Deasphalting
The residues from atmospheric distillation
of crude oils are further fractionated in a vacuum distillation (VDU) to produce two,
three or four vacuum distillates of different viscosities.
The vacuum residue contains lubricant stock of high viscosity mixed with asphalt
and resins. This oil (DAO) is produced by
solvent deasphalting which precipitates asphaltenes and resins with liquid propane.
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b - Solvent extraction (figure 9)
The vacuum distillates and the deasphalted oil (DAO) contain aromatic and naphtenic hydrocarbons
which must be removed to increase the viscosity index. The process consists of separately treating each distillate and the DAO with a solvent (furfural, n-methyl-pyrrolidone).
The solvent is mixed with the liquid feedstock and dissolves the components to be extracted. The
mixture settles in two phases: an extract phase rich in aromatics and a raffinate phase rich in paraffins.
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8 C
DistillatesRaffinate(rich in paraffins)
DAO Extract(rich in aromatics)
SolventDewaxing
Deep hydrotreating (figure 7) is sometimes used instead of solvent extraction. This process converts aromatics into naphthenes, breaks naphthene rings and isomerizes the linear paraffins. As a result low
VI materials are converted to higher VI materials, but the deep hydrotreating markedly reduces the
viscosity of the base oil.
c - Solvent dewaxing (figure 10)
Solvent dewaxing is used to reduce the n-paraffins content of the base oils in order to improve their low
temperature properties and thus preventing wax crystals forming within the normal working temperature range of the lubricant. Each raffinate is diluted and chilled with a mixture of
methylethylketone (MEK) and toluene. Wax crystallizes and is removed from the oil by filtration to produce a lube base oil in the – 9 to – 20°C pour point range according to specifications. The slack
wax from the dewaxing step may be deoiled to produce a hard wax and a by product (soft wax).
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9 B
Raffinates
Dewaxed oil
Hard waxSlackwax
Deoiling
SolventDewaxing
MEK-Toluene
Catalytic dewaxing (hydrodewaxing) is used as an alternate to solvent dewaxing. However no wax is
produced from the catalytic dewaxing (selective hydrocracking of the waxy components).
d - Finishing processes
Some base stocks, particularly premium stocks, are hydrofinished or treated with clay to improve color
and oxidation stability. A severe hydrofinishing is used in the manufacture of medicinal white oils.
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8 D
Dewaxedoil
Finished baseoil
Hydrogen
Finishingprocesses
For solvent extracted oils or conventional base oils, the VI is in the range of 90-100. Non conventional
base oils with VI over 100 are usually manufactured using deep hydrotreating which substitutes for solvent extraction.
e - Lube crude selection
The lube base oil refiner selects the crude that will provide a consistent quality of the base oils taking into account the slate of the base oil demand for a lube plant or for a system of several lube plants (for
a refiner operating several lube plants).
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RECOMMENDED PROPERTIES OF LUBE BASE OILS
• Base oils are blended with additives to yield commercial finished lubricants.
about 20% vol. additives
about 80% vol. blendedlube base oils
Automotivelubricant
D L
UB
032
B
• RECOMMENDED PROPERTIES FOR BASE OILS - (automotive base oil case)
Lubricant film
D L
UB
033
B
VISCOSITY
Fluid bases 20 cSt at 40°C Viscous bases 100 cSt at 40°C Heavy bases 30 cSt at 100°C
VISCOSITY INDEX VI
– not too high viscosity under cold temperature (start-up in winter) – not too low viscosity under hot temperature (lubricant film at 200°C)
High VI = small variation in viscosity with temperature
Automotive base oil VI 100
Automotive multigrade lubricant VI 150
POUR POINT
Base oil ability to remain liquid at low temperature – 9°C specification for most automotive base oils
OXIDATION RESISTANCE AND STABILITY
Characteristics deterioration under oxygen and temperature influences.
LUBRICATING OIL
FRENCH CUSTOM SPECIFICATIONS
Loi n°66-923 du 14/12/66
J.O. 15/12/66
Arrêté du 1/3/76
J.O. 31/3/76
DISTILLATION (NF M 07-002) % vol (including loss)
< 65% at 250°C < 85% at 350°C
EXAMPLES OF LUBE BASE OIL SPECIFICATIONS (INDUSTRY IN FRANCE)
Kinematic viscosity (cSt) Viscosity Pour point Flash Conradson Acidity
at 40°C at 100°C index point residue index
DESIGNATION min max min max min max min max max
NF T 60-100 NF T 60-136 NF T 60-105 NF T 60-118 NF T 60-116 NF T 60-112
NAPHTHENICS
Spindle
100 pale
18.7 21.0 – 33 160 0.10
Movements
550 pale
1800 red
95
103
14.5
15.5
– 24
– 9
195
230
0.10
0.10
Engines
60 pale solvent
90 pale solvent
750 pale solvent
1300 pale solvent
7.9
13.1
8.9
16.3
10,-
15.3
11.2
16.3
25
25
40
– 57
– 42
– 21
– 15
150
160
205
235
0.10
0.10
0.10
0.05
0.05
0.05
0.05
PARAFFINICS
Spindle
100 pale
19
24
– 15
160
0.10
Movements
900 red (movem. V14)
170
210
– 9
225
0.10
Cylinders
C1-160
C1-180
C1-200
800
1000
30.0
36.3
33.5
41,-
– 3
0
0
275
290
300
0.10
Engines
100 solvent
60 neutral solvent
90 neutral solvent
100 neutral solvent
150 neutral solvent
175 neutral solvent
200 neutral solvent
250 neutral solvent
350 neutral solvent
400 neutral solvent
500 neutral solvent
600 neutral solvent
17
8.8
14.5
18,-
28
32
37.5
45,-
66
76
92
109
23
9.6
16,-
23,-
32.5
35.5
43.5
51,-
75
85
102.5
125
80
95
100
100
97
102
97
97
95
95
95
95
– 9
– 15
– 12
– 9
– 9
– 9
– 9
– 9
– 9
– 9
– 9
– 9
180
150
180
190
200
210
210
215
225
230
230
240
0.10
0.01
0.02
0.02
0.05
0.05
0.05
0.10
0.15
0.15
0.15
0.20
0.10
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
Bright stock
Bright stock solvent
Bright stock MIV (V40)
30
32.5
35
38
95
80
– 9
– 9
280
280
0.90
1.80
0.05
0.10
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STRUCTURE TO PROPERTY RELATION FOR HYDROCARBONS PRESENT IN LUBE OIL CUTS
HYDROCARBON MAIN PROPERTIES
FAMILIES TYPICAL STRUCTURE
DESIRABLE DETRIMENTAL
LINEAR PARAFFINS
• HIGH VI
• GOOD OXIDATION
STABILITY
• HIGH POUR POINT
BRANCHED PARAFFINS OR
PARAFFINS WITH FEW CYCLES
• MEDIUM TO HIGH
VISCOSITY INDEX
• MEDIUM TO GOOD
OXIDATION
STABILITY
• GENERALLY LOW
POUR POINT
NAPHTHENES
• GOOD OXIDATION
STABILITY
• LOW POUR POINT
• LOW VI
AROMATICS
• GENERALLY LOW
POUR POINT
• LOW VI
• VERY POOR
OXIDATION
STABILITY
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2
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LUBE OILVACUUM
DISTILLATION
Vacuum system
VI
Very high VI
High Pour Point
High VI
Acceptable Pour Point
Pour point
nP iP and P with few rings N - A
Distillate 1
Distillate 2
Distillate 3
STANDARD BASE OIL MANUFACTURING PROCESSES
Lube base oils
3 2
3 2
VI
VI
Medium to low VI
Low Pour Point
Very high VI
High Pour Point
High VI
Acceptable Pour Point
Medium to low VI
Low Pour Point
Very high VI
High Pour Point
High VI
Acceptable Pour Point
Very high VI
High Pour Point
High VI
Acceptable Pour Point
Medium to low VI
Low Pour Point
Medium to low VI
Low Pour Point
Pour point
nP iP and P with few rings N - A
Pour point
nP iP and P with few rings
iP and P with few rings
N - A
Pour pointVacuumresidue
VI
nP
Deasphalting with propane
3 2
3 2 1
N - A
ResinsAsphalts
ATMOSPHERICRESIDUE
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B
Dewaxing
Naphtene - Aromatics extraction (with solvent)
7
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ATM
OSPH
ERIC
DIS
TILL
ATIO
N
- Furfural- NMP
SOLVENTEXTRACTION
- MEK - Toluene- MIBK - MEK
Distillate 1
GO
Distillate 2
Distillate 3
DEWAXINGFINISHING
HYDROTREATINGSTEPS
Kerosene
Light gas oil
Heavy gas oil
DEASPHALTING HYDROTREATMENT
Atmosphericresidue
Vacuumresidue
DAO
Aromaticextracts
Asphalt
Gas + naphtha
WaxesRefinedwaxes
LUBE OILBASES
Vacuumdistillates
Waxyraffinates
Dewaxedraffinates
• Flash point• Viscosity
• Viscosity index (VI) • Pour point • Colour• Stability
FUNCTION OF UNITS
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CPARAFFINIC BASE OIL MANUFACTURING SCHEME
— Block flow diagram —
CRUDEOIL
8
VACU
UM D
ISTI
LLAT
ION
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58100 48 47
42
AROMATICEXTRACTION
58%
DEWAXING
82%
HYDROFINISHING
98%
Aromaticextracts
Paraffins
17.535100 13.1 12.9
17.5
AROMATICSEXTRACTION
50%
DEASPHALTING
35%
DEWAXING
75 %
HYDROFINISHING
98%
Extract
65
Asphalt
4.4
Wax
Mass flowrate
Yield (% mass)
EXAMPLE OF OBTAINED PRODUCT YIELDSIN A CLASSIC LUBE BASE OIL REFINING UNIT
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B
10
VACUUMRESIDUE
VGOLUBE BASE OIL
150 NSVI: 102
LUBE BASE OILBRIGHT STOCK
SOLVENTVI: 102
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© 2009 - IFP Training
Paraffins
Para
ffini
c ba
se o
ils
DEW
AXIN
G
ATM
OSP
HER
ICD
ISTI
LLAT
ION
VAC
UU
MD
ISTI
LLAT
ION
Distillates
PROPANEDEASPHALTING
Asphalt
HYD
RO
TREA
TIN
G
Vacuumresidue
Atmosphericresidue
nP
nP
N
N A
A
DEWAXINGor isomerization
DEASPHALTING
ASPHALT
Vacuumdistillates
Vacuumresidue
HYDROTREATMENT
DAO
MANUFACTURING OF PARAFFINICLUBE OILS BY HYDROTREATING
PARAFFINICCRUDE OIL
Hydrocarbons used asfor lube base oils
iP + P with few rings
iP + P with few rings
10
HYD
RO
FIN
ISH
ING
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G
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Deasphalted oil /Propane separation
Asphalt 70%Propane 30%
40 to 50°C
Dilution rate 5 to 12/1
PropanePropane
Propane
Steam
Deasphalted oil + propane
Heating areaby steam coils
Asphalt / Propaneseparation
55 to 70°C
BASE OIL MANUFACTURING— Propane deasphalting —
EXTRACTIONCOLUMN
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B
30 bar
FEEDSTOCKVACUUMRESIDUE
DEASPHALTEDOIL
D.A.O.
ASPHALT
11
© 2009 - IFP Training
DEAERATOR
Extract - Furfuralseparation
Furfural
Furfural
Solvent ratio2 to 3/1
Paraffinic oil + furfural
EXTRACTOR
Vacuum
Aromatic extract + Furfural
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D
130°C
BASE OIL MANUFACTURING— Furfural extraction —
90°C
Oil - Furfuralseparation
FEEDDISTILLATE
or DAO
PARAFFINICOIL
AROMATICEXTRACT 12
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Washing solvent
FILTRATION
CRYSTALLIZATION
REFRIGERATIONUNIT
Cooling system
Solvent ratio 1 to 5/1
Solvent
Oil - solventseparation
Oil + solvent
Paraffin + solvent
Solvent
Solvent (MEK + Toluene)
Liquid raffinate+ solvent at 50°C
Liquid + solidat – 20°C
Oil kept in solid phaseby paraffin crystalls
Raffinateat 20°C
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B
Paraffin - solventseparation
Paraffincake
Paraffincake
Around 50% MEKAround 50% toluene Solvent
recovery
- 10 to -20°C
Oil + solventaspiration
Oil + solvent+ paraffin crystalls
Rotative filterprinciple
Oil remains liquidphase by solvent
reaction
BASE OIL MANUFACTURING— Solvent (MEK + Toluene) dewaxing —
PARAFF
IN
13
CHARGEFEED
PARAFFIN
DEWAXEDOIL