Lube Base Oil

© 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

00014_C_A © 2009 - IFP Training

1

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.


2

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.


3

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.

D P

CD

239

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).

D P

CD

239

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.

D P

CD

239

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).


4

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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6

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


1

2

3

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


Medium to low VI

Low Pour Point

Very high VI

High Pour Point

High VI


Very high VI

High Pour Point

High VI


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

D P

CD

367

B

Dewaxing

Naphtene - Aromatics extraction (with solvent)

7


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

D L

UB

009

CPARAFFINIC BASE OIL MANUFACTURING SCHEME

— Block flow diagram —

CRUDEOIL

8

VACU

UM D

ISTI

LLAT

ION


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

D P

CD

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B

10

VACUUMRESIDUE

VGOLUBE BASE OIL

150 NSVI: 102

LUBE BASE OILBRIGHT STOCK

SOLVENTVI: 102

9


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

D P

CD

364

G


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

D P

CD

076

B

30 bar

FEEDSTOCKVACUUMRESIDUE

DEASPHALTEDOIL

D.A.O.

ASPHALT

11


DEAERATOR

Extract - Furfuralseparation

Furfural

Furfural

Solvent ratio2 to 3/1

Paraffinic oil + furfural

EXTRACTOR

Vacuum

Aromatic extract + Furfural

D P

CD

365

D

130°C

BASE OIL MANUFACTURING— Furfural extraction —

90°C

Oil - Furfuralseparation

FEEDDISTILLATE

or DAO

PARAFFINICOIL

AROMATICEXTRACT 12


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

D P

CD

366

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

Lube Base Oil

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