Characterization of Petroleum Fractions - · PDF filepractical calculations for resins one can...

2013 AIChE Annual Meeting

Characteristics of Heavy Fractions for

Design and Operation of

Upgrading Related Processes

M. R. Riazi, Ph.D., AIChE Fellow

Professor of Chemical Engineering

Kuwait University

www.RiaziM.com

San Francisco, California

November 7, 2013 (2:45 – 3:00 PM) Room: Van Ness, Hilton

Paper 653j in Session: Alternative Fuels and Enabling Techniques I: Fuels and Petrochemicals Division

2013 AIChE Annual Meeting, San Francisco, California, November 7, 2013 2

Summary of Presentation

• Review of upgrading processes

• Characteristics of heavy fractions

• Application of a Distribution Model for Properties of Heavy Fractions

• Upgrading heavy oil with gas dissolution, a measurement technique

• Concluding Remarks


Introduction

While world demand on lighter fuels such as naphthas and middle

distillates of crude oils is on the rise, quality of world crude is decreasing

and extra heavy crudes and unconventional oils are alternative to

conventional and more sweet oils. Future refineries are dealing with

conversion of nearly all residues to light and middle distillates through

various separation and cracking processes. Optimum operation of such

units depend on the knowledge of feedstocks and products physical

properties.

2013 AIChE Annual Meeting, San Francisco, California, November 7, 2013

4

Production of Heavy Oil is Rising


Heavy oil and bitumen resources and their worldwide distribution

2013 AIChE Annual Meeting, San

Francisco, California, November

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6

Various categories of natural gas and liquid naturally occurring petroleum fluids and their

approximate hydrocarbon molecular weight distributions according to their carbon numbers

natural gas gas-condensate(NGL) light crude intermediate crude heavy oil tar sand oil shale



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Classification of Oils and Definition of Heavy Oil, Extra Heavy

Oil and Bitumen

Type of Oil API Gravity Viscosity in the Reservoir Definition of Oil

Conventional Oil

>45º Condensate

22º to 45º

Medium - light crude

Non Conventional Oil

10º to 22º

<10000cSt

at reservoir conditions

Heavy crude

<10º

<10000cSt

Mobile at reservoir conditions

Extra heavy crude

<10º

>10000cSt

Immobile at reservoir conditions

Bitumen



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Properties of light, heavy and extra heavy crudes

and residue

Classification Definition

Extra light High API gravity, low S, N and negligible aphaltene and metals

Light crude Medium range API gravity, low S, N, metals and moderate asphaltene

Heavy crude Medium range API gravity, high S, N, high metals and asphaltene

Extra-heavy/

Residue

Low API gravity and very high contaminants (S,N, metals and

asphaltenes)



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Effect of API gravity on the residue and lighter fraction

(Middle Distillate)

0

10

20

30

40

50

60

70

0 10 20 30 40

API gravity

Dis

tillati

on

Fra

ctio

n, vol. %

Residuum Lubes Gasoline+Naphtha+MD



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Relationship between different properties

and composition of various crude oils

0

200

400

600

0 100 200 300 400 500 600

Ni, wppm

V,

wp

pm

.

0

200

400

600

0 5 10 15 20 25

Asphaltene, wt. %

V,

wp

pm

.

0

100

200

300

Ni, w

pp

m .

0

10

20

30

0 10 20 30 40 50

API gravity

wt.

%

Resin

Asphaltene

10

10000

10000000

0 5 10 15 20 25

API Gravity

Vis

cosi

ty,

cpo

.



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Content of metals in different fractions of crude oils

0

300

600

900

Asphaltene Resin DOA

Heavy Crude Oil Fractions

Met

al co

nte

nt,

wp

pm

. Ni V Mg

K Na



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Sulfur and Nitrogen Contents of Heavy Oil

Sulfur and Nitrogen Contents in Light, Heavy, Extra-Heavy and Bitumen (▲, Sulfur; ∆, Nitrogen)

0

2

4

6

8

10

0 10 20 30 40 50 60 70

API gravity

S,

wt.

%

0

0.5

1

1.5

N,

wt.

%

Light Crude Oil

Production DecreasingHeavy (Extra Heavy) Crude Oil

Production Increasing



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Effect of variation in Maya crude oil properties (API gravity and sulfur

content) during one and half year time

3.44

3.46

3.48

3.5

3.52

3.54

21.40 21.45 21.50 21.55 21.60 21.65 21.70 21.75 21.80

API gravity

S,

wt.

%

≈ 0.4 °API

≈ 900 wppm S

June 1999

January 1998



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Hydrocarbo

ns

M H% H/C V d, ºA D

Asphaltene 1000 –

5000

9.2 – 10.5 1.0 – 1.4 900 14.2 4 – 8

Resin 800 –

1000

10.5 –

12.5

1.4 – 1.7 700 13 2 – 3

Oil 200 – 600 12.5 –

13.1

1.7 – 1.8 200 –

500

8 – 12 0 – 0.7

Properties of Typical Asphaltenes, Resins and Oils M is molecular weight in g/mol. H% is the hydrogen content in weight %. H/C is the hydrogen to

carbon atomic ratio. V is the liquid molar volume at 25 ºC. d is molecular diameter calculated from

average molar volume in which for methane molecules is about 4 ºA (10-10 m). D is the dipole moment

in Debye. These values are approximate and represent properties of typical asphaltenes and oils. For

practical calculations for resins one can assme M=800 g/mol and for a typical monomeric sphaltene

separated by n-heptane approximate values of some properties are as: M = 1000 g/mol. Density of

liquid ≈ Density of solid ≈ 1.1 g/cm3. Enthapy of fusion at the melting



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Carbon number and boiling range of petroleum products



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Review of Hydrocracking and

Hydroprotreating Processes


17

Heavy or

Extra heavy

crude oil

Hydroprocessing

Com

merc

ial

Fu

el

(gaso

lin

e, d

iese

l, j

et f

uel

, h

eati

ng

oil

, asp

halt

, lu

bri

can

ts,

pet

roch

em

ica

ls e

tc.)

Non

-cata

lyti

cC

ata

lyti

c

Hydrotreating

Hydrocracking

Fluid Cracking

+H2

Residue

H-Oil

LC-Fining

HYCONABC

RDS

VRDS

HYVAL

OCR

Primary processes Secondary process

Gas

Dis

till

ati

on

Distillates ( < 343 °C)

Coking

Delayed coking

Fluid coking

Flexi-coking

Hydrovisbreaking+H2

SDA DOA

Asphaltenes

Gasification

FT-Synthesis

Syngas

GasGas

LPG

DAO

A comprehensive schematic flow diagram of typical oil refinery

technologies for upgrading of heavy, extra-heavy crude oil and residue

(ASTM MNL58)



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Proposed hybrid process scheme for upgrading of heavy petroleum

[MNL58]

Distillation

Column

Crude oil

Residues (AR or VR) Solvent

Deasphalting

Gasification

Process

Fischer-Tropsch

Synthesis

Hydroprocessing

Solvent

Recovery

High value

(Middle distillates)

Asphaltene

s

Coke (ash)

Gas

Hydroisomerization



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Typical Characteristics of light crudes vacuum residua

compared with the Maya heavy crude vacuum residua

Arabian Light Arabian Heavy Ural Odessa Maya

538+ °C 538+ °C 538+ °C 538+ °C

Yield v % 16.71 25.09 21.33 32.82

Yield wt% 20.14 30.86 25.12 38.31

Density at 15°C g/ml 1.0323 1.0448 1.0180 1.0730

Specific gravity at 15,6/15,6 °C g/ml 1.0330 1.0455 1.0187 1.0738

API °API 5.48 3.93 7.40 0.28

Sulfur wt% 4.160 5.350 2.610 5.230

Kinematic Viscosity

Viscosity @ 135°C cSt 5859 1059 9143

Viscosity @ 150°C cSt 597.1 178,0 3727

Viscosity Brookfield

Viscosity Brookfield @ 135°C cP 5,825 1059 9,100

Viscosity Brookfield @ 150°C cP 581 178,0 3,673

TAN mg KOH/g 0.10 0.20 0.85 1.15

Nitrogen ppm 409 3693 5287

Nickel ppm 25.8 47.0 76.0 111.0

Vanadium ppm 91.6 171.0 226.0 564.0

Sodium ppm 1.3 <5 1.0 28.0

Concarbon wt% 21.13 23.32 16.69 29.52

Asphaltenes wt% 11.20 11.65 6.36 26.30

Vacuum Resid Properties Unit


20

Crackability tendenecy reduces with increase in aromatic content of the oil

[MNL58]


21

Typical Characteristics of Venezuelan and Canadian

Crudes and their Vacuum Residues (ASTM MNL58)


22

Factors Affecting the Conventional Hydrotreating Reactors


23

Relative Activity of Different Hydroprocessing Catalysts [MNL58] (MoS: Molybdenum Sulfie, CoS: Coballt Sulfide, NiS: Nickle Sulfide, WS: Tungsten Sulfide)



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Characterization Methods

for Heavy Fractions



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Nature of petroleum fluids hydrocarbons



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Importance of Characterization in Process Engineering

Always remember that a process simulator always do not provide you with

the most accurate design calculations. In general

Any Process

Junk input Simulator junk output results

To get a good output use good input to a simulator. A good characterization method

provides good input for a simulator resulting in optimum design and operation of plants.



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Importance of Characterization in Process Design and Operations



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Properties of Heavy Oils A Versatile Distribution Model

The bulk average property is calculated as:

A and B can be calculated from linear regression procedure

Or in terms of probability density function (PDF) can be written as:

P could be Tb, MW, or SG. For example, in terms of boiling point distribution the PDF is:



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Properties of Heavy Oils A Versatile Distribution Model

Fig. 6. Comparison of various distribution models for molar distribution of a heavy residue



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Case Study I: Application to Single Stage Distillation of a Crude Oil

Fig 9. Schematic of a single stage distillation unit operating at Ts and P



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Case Study I: Application to Single Stage Distillation of a Crude Oil

Model Prediction with Data

Figure 10- PDF for Products of Russian Crude at 400 C based on Lee-Kesler Vapor

Pressure.



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Applications in design and operation of a distillation column

Separation of Oil and Gas in a Separator

0

0.001

0.002

0.003

0.004

0.005

-100 0 100 200 300 400 500 600 700 800 900 1000

BOILING POINT, C

PR

OB

AB

ILIT

Y D

EN

SIT

Y F

UN

CT

ION

, 1

/K

CRUDE FEED

LIQUID PRODUCT

VAPOR PRODUCT



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Application in Solid Wax Separation

0

10

20

30

40

50

60

70

20 30 40

Wt%

Co

mp

on

ent C

on

cen

trat

ion

n

n-Paraffin Carbon Number

Phase Partition: Feed to Liquid & Solid Phases

Series1 Series2 Series3



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Second Case Study: Vacuum Gas Oil Hydrocracking and Prediction of

Distillation Data for its Products Introduction:

• Hydrocracking (HCR) processes are commonly used in refineries for converting

vacuum gas-oil (VGO) into higher-valued and lighter transportation fuels, namely,

naphtha, aviation turbine kerosene (ATK), and diesel. Such processes are important

for modern refineries, where hydrotreating units are upgraded to hydrocracking units.

Experiments

• A schematic diagram of the pilot plant used for the study and its configuration is shown

in Figure 1. It consists of a once-through (no recycle) microreactor followed by high

and low pressure separators.



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Figure 11. Schematic of the pilot plant used for the experimental runs.



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Specification of pilot plant reactor used for the experimental runs

• Reactor Volume: 505 ml

• Reactor internal diameter: 2.8 cm

• Volume of catalyst: 128 ml

• Catalyst was diluted with 136 ml of carborundom.

• Heated feed and hydrogen are introduced in a down co-current flow mode.

• Reactor consists of 5 reaction zones each equipped with a built-in furnace and thermocouple to

measure reactor temperature

• Vacuum Gas Oil (VGO) feedstock and the HCR catalyst (amorphous silica alumina) used in the

runs were supplied by a local refinery.

• Reaction variables: Temperature (370, 380 and 390°C) and throughputs, i.e. Liquid Hourly Space

Velocity (LHSV) (1.0, 1.5 and 2.0 h-1)

• Two experimental runs were considered in this work, Run-1 (18 tests) and Run-2 (29 tests).

• The same VGO feedstock, catalyst type and operating conditions were used for both runs.

Furthermore, fresh catalyst was loaded for each experimental run. The main difference between the

two runs is that for Run-2 the catalyst bed is kept on stream for longer period before starting the

experimental schedule and sampling.



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Specification of pilot plant reactor used for the experimental runs

Sample Analysis

• Analysis included density and simulated distillation for liquid products.

• ASTM D5002 standard test method was used to measure the density

• SimDist ASTM D2887 standard method was used to determine the boiling range

• Analysis of the off-gases (for material balance) by a refinery gas analyzer (RGA)



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Experimental Data

Specific gravity (density at 15C) measurements for all product samples collected for Run-1

(S1 to S18) and Run-2 (SC1 to SC29 with longer time for catalyst) are listed in Table 1.

Conversion is defined as the percentage of the 288°C+ fraction of the feed cracked to lighter

fractions:

Density of the products decreases (lighter products) as conversion increases.



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Experimental Data



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Model Prediction

.



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Model Prediction

.

42

Model Prediction

.



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Model Prediction



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Final Remarks



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Most Recent Applications – Aug 2009



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References

Riazi M.R., Distribution Model for Properties of Hydrocarbon-Plus Fractions. Industrial and Engineering Chemistry Research, ACS Publications 1989; 28:1731-1735.

Riazi M.R., A Continuous Model for C7+ Characterization of Petroleum Fractions. Industrial and Engineering Chemistry Research, ACS Publications 1997; 36:4299-4307.

Riazi, M. R., “Characterization of Petroleum Fractions,” ASTM International, 2007. (http://www.astm.org/DIGITAL_LIBRARY/MNL/SOURCE_PAGES/MNL50.htm)

HMS, Lababidi, Chedadeh, D., Riazi, M R, Alqattan, A., Al-Adwani, H. A. “Prediction of Product Quality for Catalytic Hydrocracking of Vacuum Gas Oil” Fuel Journal , Vol. 90, pp. 719-727 (2011).

Riazi, M. R., Eser, S., Agrawal, S., Pena Diez, J. L. “Petroleum Refining and Natural Gas Processing,” ASTM MNL58, ASTM International, 2013. (http://www.astm.org/DIGITAL_LIBRARY/MNL/SOURCE_PAGES/MNL58.htm)

http://139.141.199.1/~riazi/publication/pdf's/Fuel.pdf

http://139.141.199.1/~riazi/publication/pdf's/Fuel.pdf

http://www.elsevier.com/wps/find/journaldescription.cws_home/30420/description#description

http://www.elsevier.com/wps/find/journaldescription.cws_home/30420/description#description



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Acknowledgement

To attend 2013 AIChE Meeting was supported by Kuwait University and College of Engineering.

The experiments were conducted by the researchers/staff of Kuwait Institute for Scientific Research as reported in Fuel (V 90, p, 719, 2011)



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