A Thesis Submitted to the Chemical Engineering Department / University of

Technology in Partial Fulfillment of the Requirement for the Degree of Higher Diploma in Petroleum Refining and Gas Technology.

By

Ali Jassim Radhi (B.Sc. Chemical Engineering)

Supervised by Dr. Adel Sharif Hamadi

2012

Ministry of Higher Education and Scientific Research University of Technology Chemical Engineering Department

Upgrading of East Baghdad Resid by N-Hexane

وزارة التعليم العالي والبحث العلمي

الجامعة التكنولوجية قسم الهندسة الكيمياوية

تحسين مواصفات متبقي التقطير الجويهكسان األعتيادي بواسطة ال شرق بغدادلنفط الخام

رسالة مقدمة الى

قسم الهندسة الكيمياوية / الجامعة التكنولوجية كجزء من متطلبات نيل درجة الدبلوم العالي في

تكرير النفط وتكنولوجيا الغاز

من قبل علي جاسم راضي

)1999(بكالوريوس هندسة كيمياوية,

بأشراف

د. عادل شريف حمادي

1433ه 2012م

CHAPTER ONE INTRODUCTION

CHAPTER TWO LITERATURE

SURVEY

CHAPTER THREE EXPERIMENTAL

WORK

CHAPTER FOUR RESULTS AND DISCUSSION

CHAPTER FIVE CONCLUSION &

RECOMMENDATION

REFERENCES

CERTIFICATE

Certification of Supervisor

I certify that this thesis entitled “Upgrading of East Baghdad

Resid by N-hexane” has been prepared under my supervision as a

partial fulfillment of the requirements for the degree for Higher

Diploma in Petroleum Refining and Gas Technology at the Chemical

Engineering Department, University of Technology.

Signature:

Dr. Adel Sharif Hamadi

(Supervisor)

Date: / / 2012

In view of the available recommendations, I forward this

research for debate by the examination committee.

Signature:

Assistant Professor Dr. Mohamed Ibrahim

Deputy Head of Department For

Scientific and Post Graduate Affairs

Date: / / 2012

CERTIFICATE

Examination Committee Certificate

We certify that we have read this thesis entitled “Upgrading of

East Baghdad Resid by N-hexane” by student (Ali Jassim Radhi)

and as examining committee, examined the student in its content and

that in our opinion it meets the standards of a thesis for the degree of

Higher Diploma in Petroleum Refining and Gas Technology.

Signature:

Dr. Adel Sharif Hamadi

(Supervisor)

Date: / / 2012

Signature: Signature:

Dr. Adnan Abdul Jabbar Prof. Dr. Neran K. Ibrahim

(Member) (Chairman)

Date: / / 2012 Date: / / 2012

Approved by the University of Technology – Baghdad

Signature:

Prof. Dr. Mumtaz A. Zablouk

Head of the Chemical Engineering of Department

Date: / / 2012

Acknowledgements

i

First and foremost, praise is to Allah. Best prayer and peace be

unto, the prophet Mohammed messenger of Allah. Then, I would

like to express my sincere gratitude to my supervisor Dr. Adel

Sharif Hamadi for their helpful suggestions during this work.

I would like to thank sincerely the Research Petroleum and

Development Center for their cooperation.

I also express my sincere thanks to my friends and all others

who have helped me directly or indirectly whenever I needed

help.

Last but not the least; heartfelt thanks are due to my family

specially my mother, my father (may Allah have mercy upon him

soul), my wife, my sisters and my brothers.

Ali J. Radhi

Abstract

ii

East Baghdad heavy crude oil (22 °API) was introduced to processes of

atmospheric distillation and solvent extraction. The purpose of distillation is to

separate the light distillates (34 °C - 350 °C) which represent 35% of heavy crude,

and to obtain the reduced crude oil. The reduced crude (9 °API) extracted by

N-Hexane solvent. The extraction carried out at temperature 50 o C, solvent to RC

Ratio (3, 5, 10, 15:1 ml / ml) and mixing time 60 minutes. The results show that

API of Deasphalted Oil (DAO) increased 20 degree compassion with °API of

reduced crude oil while asphaltenes content decreased by 88.74 % and also metals

content decreased by 82.46 %. Deasphaltenes Oil (DAO) which is produced can be

used such a feedstock in FCC (Fluidized Catalytic Cracking) unit and HDS

(Hydrodesulphurization unit) or blending with light distillates to produce Synthetic

Crude Oil (SCO).

Abstract

Contents

iii

Subject Page Acknowledgments

i

Abstract ii

Contents

iii

Alphabetical

iv

Chapter One (Introduction)

1-1 Introduction 1 1-2 Aims of the present work 4

Chapter Two (Literature survey)

2-1 Solvent Extraction 5

2-2 Principles of Solubility and Solutions 5

2-3 N-Hexane 7

2-4 Upgrading of Crude Oil Residue 8 2-4-1 Cracking 8

2-4-1-1 Thermal Cracking 8

2-4-1-2 Catalytic Cracking 9

2-4-2 Hydrocracking 11 2-4-3 Solvent Deasphalting (SDA) 13

Contents

iv

2-4-4 Residue Fluidized Catalytic Cracking 15

2-4-5 Hydroconversion process 15

2-4-5-1 Fixed bed and Moving bed processes 16

2-4-5-2 Ebullated bed processes 18

2-4-5-3 Slurry processes 19 2-5 Methods of Upgrading Heavy Crude Oils

21

2-5-1 Residue Decarbonization Technology (RDCP) 22

2-5-2 Method of Upgrading a Heavy Oil Feedstock by X-Ray Treatment 22

2-5-3 Nano Catalytic Process to Upgrade Extra Heavy Crude / Residual Oils

23

Chapter Three (Experimental work)

3-1 Experimental work 25

3-1-1 Distillation stage 25

3-1-2 Separation of Asphaltenes Stage 28

3-1-2-a Mixing Stage 28

3-1-2-b Filtration Stage 28

3-1-2-c Evaporation Stage 29

Contents

v

Chapter Four (Results and Discussions)

4-1 Results and Discussions

33

4-1-1 Effect of Solvent to RCR Ratio 33

Chapter Five (Conclusions and Recommendation)

5-1 Conclusions 37

5-2 Recommendation 38

References 39

Alphabetical

vi

Alphabetical Symbol Definition

CNOOC China National Offshore Oil

Corporation

DAO Deasphaltene oil

EST ENI Slurry Technology

FCC Fluidized Catalytic Cracking

HDM Hydrodemetalization

HDN Hydrodenitrogen

HDS Hydrodesulphurization

HRH Heavy Residue Hydroconversion

HDS Hydrodesulphurization

RDCP Residue Decarbonization Combination Process

RC Residue Crude

RFCC Residue Fluidized Catalytic Cracking

ROSE Residuum Oil Supercritical Extraction

SCO Synthetic Crude Oil

SDA Solvent Deasphalting

Chapter One Introduction

- 1 -

CHAPTER ONE

UIntroduction

1-1 UIntroduction Heavy oil crude or extra heavy oil crude is any type of crude oil which does

not flow easily. It is referred to as "heavy" because its density or specific gravity is

higher than that of light crude oil. Heavy crude oil has been defined as any liquid

petroleum with an API gravity of less than 20°. Extra heavy oil is defined with

°API gravity below 10.0 °API [1].

The lack of ability to find enough light oil to replace depleted light oil reserves has

caused a monumental shift in the future of oil production. Combined with soaring

worldwide demand, the oil world is facing unprecedented production problems.

New technologies exist today to remedy heavy oil production problems and

through this heavy oil are capable of supplying the world with plenty of

transportation fuel from Medium - Heavy reserves [1].

Asphaltenes are high molecular weight polycyclic compounds containing nitrogen,

sulfur, oxygen, and metals. The relative concentrations of these compounds vary

however, in terms of the crude oil, make up a unity which makes it a useful

parameter for general comparisons of oils. All of these compounds are present in

different oils which vary from light to heavy crudes with a broad spectrum of

varying densities in which the conventional unit of gravity (°API gravity)

decreases or the oil becomes heavier, making this unit an important correlation

factor. Additional general correlation factors describing different types of oils are

the H/C ratios, which also decrease as the oil becomes heavier. Further, the polar

N, S, O compounds become concentrated in the heavy ends of crudes. The

heteroatom contents of these oils are measurable quantities and are also useful for

Chapter One Introduction

- 2 -

correlation purposes. Thus, as the sulfur and nitrogen concentrations increase, the

API value decreases, consistent with an increase in the concentrations of

compounds containing heteroatoms and increasing molecular weights. The high

molecular weight fractions also concentrate organometallic compounds [2].

The solvent deasphaltation treats the residue through a pressurized liquid-liquid

extraction, using specific properties of the solvent. The deasphaltation produces the

deasphalted oil and the asphalted residue [3].

The solvent deasphalting process (SDA) which is based on liquid–liquid extraction

by using paraffinic solvents (C4–C7) (Butane, Pentane, Hexane and Heptane) is one

of the most efficient approaches to reduce metal and asphaltene contents of heavy

oil cuts before sending them to hydro-desulphurization and Hydrocracking units.

A number of deasphalting process parameters are to be considered, amongst which

the DAO process yield and the levels of demetalization and deasphalting could be

noted. The important factors influencing the mentioned parameters are solvent

composition and ratio of the solvent to the feed, temperature, pressure and the type

of extractor equipment.

The precipitation increases substantially as the solvent/feed ratio increases up to 10

folds. Beyond this value, precipitation increases by very small amounts [4].

Extraction temperature must be maintained below the critical temperature of the

solvent, however, because at higher temperatures no portion of the residue is

soluble in the solvent and no separation occurs [5].

In industrial plants, increasing the solvent to feed ratio compensates for the DAO

yield reduction with temperature rise. In consequence, the extraction process

selectivity for paraffinic oils escalates and eventually the extracted oil will have an

improved quality due to the reduction of undesirable components [6].

The Residuum Oil Supercritical Extraction (ROSE) process is the premier

deasphalting technology available in industry today. This state-of-art process

extracts high-quality deasphalted oil (DAO) from atmospheric or vacuum residues

Chapter One Introduction

- 3 -

and other feedstocks. The asphalthene products from the Residuum Oil

Supercritical Extraction (ROSE) process is often blended to fuel oil, but can also

be used in the production of asphaltic blending components, solid fuels, or fuel

emulsions. The development of the deasphaltation technology using supercritical

fluid appears as a solution to improve the separation of the deasphalted oil from the

asphaltenes. The use of supercritical fluid has some advantages like: the difference

of the densities between the extraction phase and the refining phase is greater than

that obtained by the conventional liquid extraction, becoming the separation

between the phases easier; the mass transport is faster using the supercritical fluid;

the quantity and the quality of the deasphalted oil can be easily controlled by

adjusting the temperature and the pressure of the extraction system and the

efficiency to recover the oil is a function of the density of the supercritical fluid

[7].

Direct hydro-desulphurization followed by Hydrocracking of crude oil heavy cuts

and vacuum residues is one of the best methods of heavy residue upgrading in

refining industry. But, problem emerges when metal and asphaltene contents of

residue are high. In fact, the presence of these compounds adversely influences the

activities of the hydro-desulphurization and Hydrocracking catalysts[6].

The aim of this work is improving properties (°API, Asphaltenes content and

Metals content) of reduced crude oil by solvent extraction (N-hexane).

Deasphaltenes Oil (DAO) which is produced can be used such a feedstock in FCC

(Fluidized Catalytic Cracking) unit and HDS (Hydrodesulphurization unit) or

blending with light distillates to produce Synthetic Crude Oil (SCO).

Chapter One Introduction

- 4 -

1-2 Aims of the present work

The aim of this work is improving properties (°API, Asphaltenes content

and Metals content) of reduced crude by solvent extraction (N-hexane).

Deasphaltenes Oil (DAO) which is produced can be used such a feedstock in FCC

(Fluidized Catalytic Cracking) unit and HDS (Hydrodesulphurization unit) or

blending with light distillates to produce Synthetic Crude Oil (SCO).

Chapter Two Literature survey

- 5 -

CHAPTER TWO

Literature survey

2-1 Solvent Extraction The term solvent extraction refers to the distribution of a solute between two

immiscible liquid phases in contact with each other, i.e., a two-phase distribution

of a solute. It can be described as a technique, resting on a strong scientific

foundation. Scientists and engineers are concerned with the extent and dynamics of

the distribution of different solutes organic or inorganic and its use scientifically

and industrially for separation of solute mixtures [8].

2-2 Principles of Solubility and Solutions Solvent extraction is another name for liquid–liquid distribution, that is, the

distribution of a solute between two liquids that must not be completely mutually

miscible. Therefore, the liquid state of aggregation of matter and the essential

forces that keep certain types of liquids from being completely miscible are proper

introductory subjects in a study of solvent extraction. Furthermore, the distribution

of a solute depends on its preference for one or the other liquid, which is closely

related to its solubility in each one of them. Thus, the general subject of solubilities

is highly relevant to solvent extraction.

In a solution, the solute particles (molecules, ions) interact with solvent molecules

and also, provided the concentration of the solute is sufficiently high, with other

solute particles. These interactions play the major role in the distribution of a

solute between the two liquid layers in liquid–liquid distribution systems.

Consequently, the understanding of the physical chemistry of liquids and solutions

is important to master the rich and varied field of solvent extraction.

Chapter Two Literature survey

- 6 -

Solvent extraction commonly takes place with an aqueous solution as one liquid

and an organic solvent as the other. Obviously, the extraction process is limited to

the liquid range of these substances. Since solvent extraction is generally carried

out at ambient pressures, the liquid range extends from about the freezing

temperature up to about the normal boiling temperature.

If, however, high pressures are applied (as they are in some solvent extraction

processes), then the liquid range can extend up to the critical temperature of the

substance. Supercritical fluid extraction beyond the critical temperature (such as

decaffeination of coffee with supercritical carbon dioxide) is a growing field of

application of solvent extraction. It has the advantages that the properties of the

supercritical fluid can be fine-tuned by variation of the pressure, and that this

“supercritical solvent” can be readily removed by a drastic diminution of the

pressure, but has drawbacks related to the high temperatures and pressures often

needed [8].

Chapter Two Literature survey

- 7 -

2-3 N-Hexane Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane

with six carbon atoms. Hexane, a colorless liquid with a slightly disagreeable odor,

is the straight-chain alkane with six carbon atoms. It evaporates very easily into the

air and dissolves and highly flammable. It is insoluble in water and miscible with

alcohol, chloroform, and ether. It is used primarily to produce solvents when it is

mixed with similar chemicals. Common names for these solvents are commercial

hexane, mixed hexanes, petroleum ether and petroleum naphtha. The major use of

n-hexane is to extract vegetable oils from crops due to its narrow distillation range

and selective power. Its wide usages are in the rubber industry as a base for rubber

cement and in tyre manufacture and in contact adhesives, paints and inks, where

fast drying and ability to suspend are required. Hexanes are chiefly obtained by the

refining of crude oil. The exact composition of the fraction depends largely on the

source of the crude oil and the constraints of the refining [9].

Chapter Two Literature survey

- 8 -

2-4 Upgrading of Crude Oil Residue Refinery residue is the hydrocarbon oil remaining after distillates have been

removed from petroleum. Residue upgrading processes are increasingly important

in the modern refinery because of the continuing decline in the demand for fuel oil,

their main use. At the same time, demand for motor fuels is increasing and is

forecast to continue to do so the next two decades. These volume trends, when

coupled with the increasing demand for clean, low-sulfur fuels, ensure the need for

additional and better residue upgrading processes will also continue. To upgrade

refinery residues, metals, sulfur, carbon residue, and nitrogen need to be removed

and the high boiling components converted to lower boiling products.

2-4-1 Cracking Cracking is a petroleum refining process in which heavy molecular weight

hydrocarbons are broken up into light hydrocarbon molecules by the application of

heat and pressure, with or without the use of catalysts, to derive a variety of fuel

products. Cracking is one of the principal ways in which crude oil is converted into

useful fuels such as motor gasoline, jet fuel and home heating oil [10].

2-4-1-1 Thermal Cracking In 1913, the thermal cracking process was developed. In this process,

heavy fuels containing large molecules are broken into smaller ones to produce

additional gasoline and distillate fuels by application of both pressure and intense

heat. Thermal cracking is a radical chain process. The chain process contains three

main stages: chain start, chain growth and chain termination [11].The majority of

the thermal cracking processes temperatures of (455 °C to 540 °C) and pressures of

(7 to 68) atm., were used to break down, rearrange, or combine hydrocarbon

molecules. However, this method produced large amounts of solid, unwanted coke.

Chapter Two Literature survey

- 9 -

This early process has evolved into the following application of thermal cracking:

1-visbreaking, 2-steam cracking, and 3-coking [10]. Figure (2-1) shows one stage

thermal cracking [12].

Figure (2-1): One Stage Thermal Cracker [12].

2-4-1-2 Catalytic Cracking Catalytic cracking is the most important and widely used refinery

process for converting heavy oils into more valuable gasoline and lighter products.

Originally cracking was accomplished thermally but the catalytic process has

almost completely replaced thermal cracking because more gasoline having a

higher octane and less heavy fuel oils and light gases are produced. The light gases

produced by catalytic cracking contain more olefins than those produced by

thermal cracking. The cracking process produces carbon (coke) which remains on

the catalyst particle and rapidly lowers its activity. To maintain the catalyst activity

at a useful level, it is necessary to regenerate the catalyst by burning off this coke

Chapter Two Literature survey

- 10 -

with air. As a result, the catalyst is continuously moved from reactor to regenerator

and back to reactor [12]. Figure (2-2) shows the two stage catalyst regeneration

[12].

The cracking reaction is endothermic and the regeneration reaction exothermic.

Some units are designed to use the regeneration heat to supply that needed for the

reaction and to heat the feed up to reaction temperature. These are known as ‘‘heat

balance’’ units.

Average riser reactor temperatures are in the range (480 °C – 540 °C); with oil feed

temperatures from (260 °C – 425 °C) and regenerator exit temperatures for catalyst

from (650 °C – 815 °C). The catalytic-cracking processes in use today can all be

classified as either moving-bed or fluidized-bed units. There are several

modifications under each of the classes depending upon the designer or builder, but

within a class the basic operation is very similar. Also catalytic cracking relatively

costly process [13].

Figure (2-2): Fluidized Catalytic Cracking unit [12].

Chapter Two Literature survey

- 11 -

2-4-2 Hydrocracking Hydrocracking is a two-stage process combining catalytic cracking and

hydrogenation, wherein heavier feedstocks are cracked in the presence of hydrogen

to produce more desirable products. The process employs high pressure, high

temperature, a catalyst, and hydrogen. Hydrocracking is used for feedstock that are

difficult to process by either catalytic cracking or reforming, since these feedstocks

are characterized usually by a high polycyclic aromatic content and/or high

concentrations of the two principal catalyst poisons, sulfur and nitrogen

compounds [14].

The hydrocracking process largely depends on the nature of the feedstock and the

relative rates of the two competing reactions, hydrogenation and cracking. When

the feedstock has a high paraffinic content, the primary function of hydrogen is to

prevent the formation of polycyclic aromatic compounds. Another important role

of hydrogen in the hydrocracking process is to reduce tar formation and prevent

buildup of coke on the catalyst. Hydrocracking produces relatively large amounts

of isobutane for alkylation feedstock. Hydrocracking also performs isomerization

for pour-point control and smoke-point control, both of which are important in

high-quality jet fuel [14]. Hydrocracking reactions are normally carried out at

average catalyst temperatures between (290 °C to 400 °C) and at reactor pressures

between (83 and 138 atm.). The circulation of large quantities of hydrogen with the

feedstock prevents excessive catalyst fouling and permits long runs without

catalyst regeneration. Careful preparation of the feed is also necessary in order to

remove catalyst poisons and to give long catalyst life [13]. This processes less coke

formation from catalytic cracking but costly process.

It was shown in thermal and catalyst cracking that it is impossible to convert a

hundred percent of the crude oil residue to light fractions. The main reason for this

is that cracking reactions need to be accompanied by hydrogen transfer reactions in

order to stabilize the product. It is obvious that light fractions such as gasoline or

Chapter Two Literature survey

- 12 -

diesel fractions are more hydrogen rich than coke and residue by-products of

thermal or catalytic cracking processes. This means that hydrogen transfer

proceeds from heavy fractions to light cracking products during the cracking

processes. However, the complete conversion of cracking feed to light fractions is

impossible because of the shortage of hydrogen in the feed. Also, heteroatom

compounds present in the feed tend to form coke on the catalysts [11]. Figure (2-3)

shows schematic of a two-stage hydrocraking unit [14].

Figure (2-3): Schematic of a Two-Stage Hydrocraking Unit [14].

Chapter Two Literature survey

- 13 -

2-4-3 Solvent Deasphalting (SDA) Solvent deasphalting of vacuum residues has been used in the

manufacture of lubricating oil to separate out the heavy fraction of crude oil

beyond the range of economical commercial distillation, using propane as solvent.

The feed to the deasphalting unit is usually a vacuum resid with a 950 0F TBP cut

point. Over time, this process has come to be used to prepare catalytic cracking

feeds, hydrocracking feeds, hydrodesulfurizer feeds, and asphalts.

Studies have shown that high yield of oil can be obtained, while limiting

asphaltenes and metals, by using the proper heavier solvent. Thus, extraction rates

from 65 to 85% of deasphalted oil (DAO) have been obtained. Whereas vacuum

residue is a very difficult feed stock for catalytic processes, DAO can be easily

processed, like other heavy distillates. The asphalt produced can be blended with

straight-run asphalts or blended back with fuel oil.

Modern solvent deasphalting units usually use a blend of light hydrocarbon

solvents (C5-C6 paraffinic cut) to allow maximum operating flexibility. The

solubility of oil in solvent at a fixed temperature increases as the concentration of

heavier components in the solvent increase. Selectivity is the ability of the solvent

to separate paraffinic and sometimes resinous oils from the asphalt or vacuum resid

feed. As the metals, sulfur, and nitrogen are generally concentrated in the larger

molecules, the metal, sulfur, and nitrogen content of deasphalted oil is

considerably reduced [15]. Figure (2-4) shows Schematic flow diagram of

UOP/FW USA SDA process [6].

Chapter Two Literature survey

- 14 -

Figure (2-4): Schematic flow diagram of UOP/FW USA SDA process [6].

Table (2-1): Properties of DAO product in SDA and ROSE processes [16], [17].

SDA ROSE

Properties Propane Butane Pentane Propane Butane Pentane Asphalt. Wt.%

0.5< 0.5< 0.5< 0.5< 0.5< 0.5<

Vanadium (ppm)

10.3 19 50 2.5 8 18

Nickel (ppm)

2.8 4.6 12 1< 1.2 3

Chapter Two Literature survey

- 15 -

2-4-4 Residue Fluidized Catalytic Cracking

Residue Fluidized Catalytic Cracking, (RFCC), is a well established

approach for converting a significant portion of the heavier fractions of the crude

barrel into a high-octane gasoline blending component. RFCC, which is an

extension of conventional FCC technology for applications involving the

conversion of highly-contaminated residues, has been commercially proven on

feedstocks ranging from highly contaminated gas oils to atmospheric and vacuum

residue blends. In addition to high gasoline yields, the RFCC unit also produces

gaseous, distillate and fuel oil-range products. The RFCC unit's product quality is

directly affected by its feedstock quality. In particular, unlike hydrotreating, RFCC

redistributes sulfur, but does not remove it from the products. Consequently,

tightening product specifications have forced refiners to hydrotreat some, or all, of

the RFCC's products. Similarly, in the future the SOx emissions from an RFCC

may become more of an obstacle for residue conversion projects. For these

reasons, a point can be reached where the RFCC's profitability can economically

justify hydrotreating the RFCC's feedstock. As an integrated conversion block,

residue hydrotreating and RFCC complement each other and can offset many of

the inherent deficiencies related to residue conversion [18].

2-4-5 Hydroconversion process

The term hydroconversion is used to signify processes by which

molecules in petroleum feedstocks are split or saturated with hydrogen gas while

tumbling boiling ranges and impurities content from petroleum fractions.

Hydroprocessing is a broad term that includes hydrocracking, hydrotreating, and

hydrorefining. To meet the gradual changes in petroleum stipulate, in particular a

reduced demand for heavy fuel oil, advanced technologies for residue

Chapter Two Literature survey

- 16 -

hydroprocessing are now extremely necessary. A refining process is needed for

treating heavy petroleum fractions (atmospheric or vacuum oil residue) in the

presence of catalysts and hydrogen at high pressure.

The various processes are differentiated on the basis of the type of reactors, Fixed

bed processes (the most common at the end of the twentieth century), though

sound, do not appear able to adequately treat feedstocks with high contents of

asphaltenes, metals and other heteroatoms, due mainly to problems relating to the

deactivation of the catalysts.

Technologies of the ebullated bed type perform well even with relatively heavy

feedstocks. Slurry processes, which operate with dispersed catalysts, ensure good

feedstock upgrading performances, in addition to considerable flexibility [6].

2-4-5-1 Fixed bed and Moving bed processes Fixed bed processes are traditionally characterized by the presence of

HDM (Hydrodemetalization) stages and partial cracking, plus the HDS

(Hydrodesulphurization) stage. The reactors, of trickle flow type, are normally

large due to the low space velocities and the large quantities of catalysts needed.

The temperature, which increases from top to bottom due to the exothermic nature

of the reactions, is controlled by adding quench gas. The temperatures do not

normally exceed (400 - 420) °C, and pressures may be up to 160 bar. Space

velocities, usually low, must be such as to ensure sufficient wetting of the catalyst.

In moving bed processes, which are relatively less common, the feedstock and

hydrogen may circulate in equicurrent, as in the simplified diagram shown in

figure (2-5), and in countercurrent. In these processes, too, the second stage

reactors are generally of a fixed bed type. The catalyst moves towards the bottom

only during operations to extract the depleted catalyst (from the bottom). The slight

Chapter Two Literature survey

- 17 -

expansion of the catalyst, in the form of pellets, caused by the flow of the

feedstock, creates some problems with friction and mechanical erosion. However,

this disadvantage and that represented by more complex operating procedures is

countered by the advantage of longer working cycles with respect to fixed beds

[15].

Figure (2-5): Section of reactors for a moving bed process [18].

Chapter Two Literature survey

- 18 -

2-4-5-2 Ebullated bed processes

Processes of this type are characterized by the fact that the circulation of the

feedstock and the hydrogen from bottom to top keeps the catalyst in suspension

(Figure (2-6); a recirculation pump for liquid products regulates the expansion of

the bed. These reactors are large, being up to 30 m tall and with diameters of up to

5 m; the volume must be suitably increased to take account of the expansion of the

catalytic bed (about 30-50%). In this case, too, some friction between the particles

of catalyst is unavoidable. The flow is agitated, rather than of piston type as in

fixed bed reactors; the temperature profile is isothermal. This, alongside the

modest and controllable loss of pressure, represents one of the advantages of this

type of process.

The catalyst may be added and removed either continuously or intermittently, thus

avoiding variations over time in the yield and quality of products, typical of fixed

bed processes. However, the consumption of catalysts is higher than for fixed beds,

since the catalyst removed is found in varying stages of saturation and

deactivation. Operating procedures are also more complex. With high conversion

rates, furthermore, the quality of the residue is generally fairly poor [19].

Chapter Two Literature survey

- 19 -

Figure (2-6): Diagram showing how an ebullated bed reactor works [19]. 2-4-5-3 Slurry processes These processes, to an even greater extent than ebullated bed processes,

are suitable for treating residues with high impurity content. The unit consists of

one or more reactors (which may be of fixed bed type) with the feedstock,

hydrogen and catalyst (in the dispersed phase) circulating from bottom to top.

The catalyst generally consists of finely dispersed metal sulphides (of iron and/or

molybdenum), generated in situ by the decomposition of a precursor. The catalyst

does not promote cracking, which is of exclusively thermal type, whilst it activates

the desulphurization, free radical quenching and hydrogenation reactions. The

Chapter Two Literature survey

- 20 -

velocity of the liquids and gas must be sufficiently high to keep the catalyst

dispersed; for the rest, conditions are similar to those of the preceding class of

processes.

The processes under examination are often still in the pilot or pre-industrial stage.

A recent process, developed by ENI and named EST (ENI Slurry Technology),

stands out for the fact that it combines the HDM/HDN/HDS stage using a MoS2

catalyst with a deasphalting and asphaltene recycling operation, and the optional

recycling of deasphalted oil. This process is also characterized by high conversion

rates and high quality products, without the simultaneous production of fuel oil

[20].

Figure (2-7): EST Simplified Process Flow Diagram [21].

Chapter Two Literature survey

- 21 -

2-5 Methods of Upgrading Heavy Crude Oils There are other types of petroleum that are different from conventional

petroleum in that they are much more difficult to recover from the subsurface

reservoir. These materials have a much higher viscosity (and lower API gravity)

than conventional petroleum. Heavy oils are more difficult to recover from the

subsurface reservoir than light oils. The definition of heavy oils is usually based on

the API gravity or viscosity, and the definition is quite arbitrary although there

have been attempts to rationalize the definition based on viscosity, API gravity,

and density [22]. Oil transportation has become a complex and highly technical

operation. One of the major difficulties in the pipe line transportation is the high

viscous fluids that require efficient and economical ways to transfer the heavy

crude [23].

Most of the world refineries are equipped with alloys capable of handling sweet

light crude, which is most suitable for refining into gasoline, gas oil and heating

oil. On the other hand, refining of heavy crude is difficult and is associated with

operational problems. The problems arise from the increased risk of corrosion,

equipment failures, and downtime of process units. .To make matters worse, many

of the compounds are unstable during refining operations and they break into

smaller components or combine with other constituents. These current events are

facing the oil industry with many decisions and technological challenges not only

regarding the methodologies of producing heavy oil, transportation and refining of

heavy oil, but also evaluating the value and optimum utilization of this produced

oil, including crude oil segregation, up-grading and blending approaches [24].

Chapter Two Literature survey

- 22 -

2-5-1 Residue Decarbonization Technology (RDCP) Because of increasing production of heavy crude oil and increasingly

strict laws of environmental protection, residue processing is of great importance.

Residue processes can be divided into two ways, hydrogenation and

decarbonization processes in terms of reaction theory.

Delayed coking, visbreaking and solvent deasphalting had made great progress

since 1990. However, conventional decarbonization process could not match the

requirements of effective use oil sources. For example, delayed coking is a kind of

heat treatment which has poor selectivity and control; deoiled asphalt obtained by

solvent deasphalting process is difficult in wholesale application.

In order to overcome the above shortages, China National Offshore Oil

Corporation (CNOOC) developed a new method of upgrading heavy oil: Residue

Decarbonization Combination Process (RDCP). RDCP is an evolutionary new

process which aims at improving the yield of light cuts and realizing the wholesale

application of carbon enriched component. RDCP processes simple in operation,

low in equipment and operation cost. It only has good reaction selectivity and easy

control, but also can improve the product’s structure and character [25].

2-5-2 Method of Upgrading a Heavy Oil Feedstock by X-Ray Treatment

A pretreatment process is described for heavy hydrocarbon oil feedstock,

such as oils extracted from tar sands. The feedstock is passed through a heated,

continuous flow electron or x-ray treatment zone. The process is designed to allow

the feedstock to be conditioned with ozone-containing air, steam or a hydrogen

donor gas prior to electron/x-ray treatment. The ozone-containing air stream may

be the stream produced in the electron treatment zone. After conditioning, the

heavy oil is heated to a specified temperature and uniformly treated with high-

Chapter Two Literature survey

- 23 -

energy beams of electrons or x-rays. A key feature of the invention is the

electron/x-ray treatment zone may use multiple accelerators or a beam splitter to

ensure acceptable dose distributions in the flowing feedstock. Another key feature

is the recirculation of volatiles back into the feedstock. According to the novel

feature, the process produces a treated feedstock having a lower average molecular

weight and boiling point than the original feedstock, without significant coke

formation. The fraction of gas oil collected during distillation is increased

significantly [26].

2-5-3 Nano Catalytic Process to Upgrade Extra Heavy Crude / Residual Oils Heavy Residue Hydroconversion (HRH) is developed and designed to

convert any type of heavy residual oil as well as extra heavy crude oil. This

technology is based on nano catalyst and having this new concept, all problems

related to asphaltene micelles and choking of catalyst pores are solved. Chemical

structure of this catalyst enables HRH to utilize any amount of sulfur and reduce it

at least 60 % and also any amount of heavy metals and converts almost all heavy

metals to metal oxides as by product. Conversion of HRH process is high (up to

95%) and it can upgrade feedstock from less than 5 °API to more than 34 °API

with more than 100 vol. % yield.

The HRH process includes catalyst regeneration unit for recycling up to 95 % of

spent catalyst. This unit boosts the economy of HRH process and due to nature of

catalyst, this process do not need any sophisticated processing for catalyst

preparation. Metal compound precursors are raw materials for HRH process so this

plant is self-sufficient with minimum dependence to sophisticated chemical supply.

It makes HRH an attractive process for wellhead application in remote areas.

Chapter Two Literature survey

- 24 -

Light gases produced in this process are useable as feedstock of its hydrogen plant.

HRH also produces steam; these two by products make HRH more attractive for

wellhead applications.

Beside wellhead applications, this technology is suitable for refinery application.

New residue free refinery schemes are developed based on HRH. This technology

is also suitable for revamping existing refineries. Some real cases are developed by

utilizing HRH and the results indicating higher added value [27].

Chapter Three Experimental work

- 25 -

Chapter Three

UExperimental Work

3-1 UExperimental work 3-1-1 UDistillation stage:-U

The distillation process for separation of light distillates from East

Baghdad heavy crude oil was achieved by computerized laboratory distillation

apparatus (according ASTM 5236) (PIGNAT COMPANY, FRANCE). Figure (7)

shows the schematic diagram of the laboratory distillation apparatus, this

distillation apparatus available in Petroleum Research and Development Center.

The physical properties and distillation results are shown in Table (3-1).

Chapter Three Experimental work

- 26 -

Table (3-1): Physical Properties of East Baghdad Crude Oil from Oil Middle Company.

Preliminary distillation (IP 24/55)

Value Properties

Vol. % Temperature, ºC

0.922 Specific gravity 15.6/15.6 ºC

- IBP(85 ºC) 22 API gravity

3.5 100 47 Viscosity at 37.5 ºC, Cs

5 125 5.044 Sulfur content, wt. %

8.6 150 88 Vanadium, ppm 11.6 175

15.1 200 38 Nickel, ppm 18.4 225 42.66 Saturate compounds, wt. %

23 250 23.87 Naphthene compounds, wt. %

27.5 275 17.8 Polar aromatic

compounds,wt.%

33.7 300 15.67 Asphaltene content,wt. %

Chapter Three Experimental work

- 27 -

Figure (3-1): Schematic Diagram of the Laboratory Distillation Unit.

1- Flask 2- Heating 3- Column 4- Condenser 5- Intermediate Receiver of fractions 6- Final Receiver of fractions 7- Cold Trap 8- Water Bath 9- Vacuum pump

1

3

4

5

6

7 8

9

2

Chapter Three Experimental work

- 28 -

3-1-2 USeparation of Asphaltenes Stage: Asphaltenes were separated from atmospheric residue (350 + oC)

obtained from distillation stage by extraction with solvent (N-Hexane), the

physical properties are shown in table (3-2). PONA tests of N-Hexane, °API,

Asphaltene Content and metals content (vanadium and nickel)) of atmospheric

residue are given in Tables (3-3) and (3-4) respectively. These examinations took

place in Petroleum Research and Development Center.

The separation process consists of three stages: mixing, filtration and solvent

recovery, which are described as follows:-

3-1-2-1 UMixing Stage:

Figure (3-2) shows a scheme of mixing process. Mixing was carried out

using 1-liter 2-neck glass flask, magnetic stirrer, heating mantle, high efficiency

condenser and thermometers. Atmospheric residue was mixed with solvents of N-

Hexane at constant temperatures of 50 o C, Solvent to RC volumetric ratio were 3,

5, 10, 15:1 for mixing time of about 1 hour and rotational speed= 400 rpm. An

efficient vertical condenser operating at total reflux was mounted on the mixing

flask in order to decrease the solvent losses to the minimum. After the mixing step

was completed, the solvent-oil mixture was left for 1 hour at ambient temperature

to let asphaltenes settle to the bottom of the flask.

3-1-2-2 UFiltration Stage:

In order to filteration of the solvent-oil mixture in a reasonable time, a

vacuum filtration unit was assembled, which consisted of a filtration flask,

Buchner funnel, vacuum pump and trap for condensing the high volatility solvent

in order to avoid vacuum pump damage. Figure (3-3) shows a scheme of the

filtration unit. The filter paper (Whatman no (1001-185)) was wetted with solvent

Chapter Three Experimental work

- 29 -

before the filtration step, and at the end of the filtration, introduced to a hot

electrical furnace at temperature (100 -125) ° C to evaporate the solvent associated

with the precipitated asphaltenes. The dried filter paper was then weighted to

estimate the percentage of asphaltenes yield.

3-1-2-3

Solvent and deasphaltened oil introduced to distillation unit in order to

recycle the solvent from Deasphaltened Oil (DAO). The percentage of solvent

recovery (N-Hexane) was (83 – 91) vol. %.

Table (3-2): Physical Properties of N-Hexane.

Properties Value

Molecular weight 86.10

Density (g/cm3 @ 20° C) 0.66

Boiling point (° C) 68.95

Melting point (° C) - 95.3

Chapter Three Experimental work

- 30 -

Table (3-3): PONA tests of Solvent (N-Hexane) by Gas Chromatograph (Dani 1000 model) apparatus.

Table (3-4): Physical Properties of Atmospheric Residue.

n-P Wt % i-P Wt %

n-C6 97.885 2MC5 0.1481

n-C7 0.05 3MC5 0.971

n-C8 0.0785 2,4DMC5 0.7012

i-C7 0.1663

Total 98.0135 1.9866

Properties Value Method

API 9.66

ASTM D 1298

Asphaltene (g)

12.7

IP 143/78

Asphaltene Content (wt %) 23 IP 143/78

Vanadium (ppm) 90 UV AFB 100

Nickel (pmm) 35.2 UV AFB 100

Chapter Three Experimental work

- 31 -

Evaporation Stage:

Figure (3-2): Scheme of the Mixing Unit.

1- Heater & magnetic stirrer 2- Flask 3- Condenser column 4-Thermometer 5- Water input 6- Water output

1

3

4

2

5 6

Chapter Three Experimental work

- 32 -

Figure (3-3): Scheme of the Filtration Unit. 1- Vacuum pump 2, 3 - Conical flask 4 - Buchner funnel

2

1

4

3

Chapter Four Results and Discussions

- 33 -

Chapter Four

4-1 UResults and Discussions The results of DAO are shown in Table (4-1). The effective parameters of process

included in this table are API, asphaltene content and metals content (Vanadium

and Nickel). 4-1-1 UEffect of Solvent to RC Ratio

Figure (4-1) shows the effect of increasing in solvent to RC Ratio on the °API of

deasphaltene oil (DAO). In this case, increasing the solvent to RC Ratio led to the

increase of °API due to increasing solvent power and selectivity for removing

asphaltenes [28].

Figure (4-2) was shown the effect of increasing solvent to RC Ratio on the removal

percentage of asphaltene. In this case, increasing solvent to RC Ratio led to

increasing percentage of asphaltenes removal. This behavior is due to increasing

solvent power and selectivity toward asphaltenes removal [28].

Figures (4-3) and (4-4) show the effect of increasing solvent to RC Ratio on

Vanadium and Nickel reduction respectively. In this case, increasing solvent to RC

Ratio led to increasing metals reduction due to increasing removing of asphaltenes.

Chapter Four Results and Discussions

- 34 -

The paraffinic solvent capable to improve properties of deasphaltene oil (DAO)

because the paraffinic solvent capable to soluble oil paraffin but it insoluble the

asphaltenes [29].

DAO is normally used as FCC and hydrocracking feedstocks due to its low metal

(Ni + V) contents [30].

Table (4-1): Tests results of DAO using N-Hexane as a solvent.

(Solvent / RC) Ratio

Properties 3/1 5/1

10/1 15/1

API of DAO 14.56 17.23

20.43 20.81

Removed Asphalting (g.) 5.43 7.82

10.89 11.24

Asphalting content (wt. %) 14.54 9.76

3.62 2.92

Vanadium (pmm) 56.61 42.61

21.49 17.78

Nickel (ppm) 15.56 13.9

9.87 8.37

Chapter Four Results and Discussions

- 35 -

Figure (4-1): Effect of Solvent: RC Ratio by volume on API at 50 0C.

Figure (4-2): Effect of Solvent: RC Ratio by volume on Removed Asphaltene at 50 0C.

0

5

10

15

20

25

3 ⁄ 1 5 ⁄ 1 10 ⁄ 1 15 ⁄ 1

API

of D

AO

Solvent:RC Ratio

N-Hexane

02468

10121416

3 ⁄ 1 5 ⁄ 1 10 ⁄ 1 15 ⁄ 1

Asp

halte

ne C

onte

nt (w

t.%)

Solvent:RC Ratio

N-Hexane

Chapter Four Results and Discussions

- 36 -

Results and Discussion

Figure (4-3): Effect of Solvent: RC Ratio by volume on Vanadium (ppm) for RC at 50 0C.

Figure (4-4): Effect of Solvent: RC Ratio by volume on Nickel (ppm) for RC at 50 0C.

0

10

20

30

40

50

60

3 ⁄ 1 5 ⁄ 1 10 ⁄ 1 15 ⁄ 1

Vana

dium

(ppm

)

Solvent:RC Ratio

N-Hexane

0

5

10

15

20

3 ⁄ 1 5 ⁄ 1 10 ⁄ 1 15 ⁄ 1

Nic

kel (

ppm

)

Solvent:RC Ratio

N-Hexane

Chapter Five Conclusions and Recommendation

- 37 -

Chapter Five

UConclusions and Recommendations

5-1 UConclusions

1- Removing asphaltenes from reduced crude lead to improve its properties

such as API, Asphaltene content and Metals content (Vanadium and Nickel).

2- Increasing the solvent to RC Ratio cause in increasing the API of DAO and

other properties.

3- Beast ratio of S/RC was 15/1 to improve of properties of DAO.

Chapter Five Conclusions and Recommendation

- 38 -

5-2

1- Upgrading of reduced crude properties with other solvents such as

propane, Butane and Pentane, and various mixtures of these

components at varied temperature and pressure.

Recommendation

References

- 39 -

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