Petroleum Refining & Petrochemicals

LISTEN...LEARN...THINK...GROW 1

Welcome to

Petroleum Refining &

PetrochemicalsECHM 404

Zin-Eddine Dadach

2013-2014


L.O’s of the course Describe refinery products and feed stock qualities

Differentiate between atmospheric and vacuum crude oil distillation units

Explain the process and principles used for hydrotreating, catalytic reforming, and isomerization.

Explain the process and principles for coking, catalytic cracking, and hydrocracking units

Describe the petrochemical industry and discuss the properties and manufacture of some typical end products

Highlight the common chemical reactions involved in the production of petrochemicals.

Perform tasks using the internet to retrieve information about the markets for crude oil, petroleum products, and petrochemical end products.

L.O #1:

Describe Refinery

products and feed stock

qualities

Crude oil is one of the most valuable commodities in the

world, but only after it has been refined into petroleum

products.



WHAT IS PETROLEUM OR

CRUDE OIL?

Petroleum (Latin Petroleum derived from Greek πέτρα

(Latin petra) - rock + έλαιον (Latin oleum) - oil)

Crude oil is a naturally occurring liquid found in

formations in the Earth consisting of a complex

mixture of hydrocarbons (mostly alkanes) of various

lengths.

Crude oil may also be found in semi-solid form mixed

with sand, as in the Athabasca oil sands in Canada,

where it may be referred to as crude bitumen.


WHAT IS CRUDE OIL?

Crude oils are in liquid form containing complex mixtures of many different hydrocarbon compounds. Crude oils vary in appearance and composition from one oil field to another.

Crude oils range in consistency from water to tar-like solids, and in color from clear to black.

Crude oils are generally classified as paraffinic, naphthenic, or aromatic, based on the predominant proportion of similar hydrocarbon molecules.


MAIN COMPONENTS OF CRUDE OILS

Carbon - 84%

Hydrogen - 14%

Sulfur - 1 to 3% (hydrogen sulfide, sulfides, disulfides, elemental sulfur)

Nitrogen - less than 1% (basic compounds with amine groups)

Oxygen - less than 1% (found in organic compounds such as carbon dioxide, phenols, ketones, carboxylic acids)

Metals - less than 1% (nickel, iron, vanadium, copper, arsenic)

Salts - less than 1% (sodium chloride, magnesium chloride, calcium chloride)


MAJOR HYDROCARBONS IN

CRUDE OIL

The approximate length range is C5H12 to C18H38.

Any shorter hydrocarbons are considered natural gas or natural gas liquids,

while long-chain hydrocarbons are more viscous, and the longest chains are part of bitumen or asphalt.

http://en.wikipedia.org/wiki/Natural_gas

http://en.wikipedia.org/wiki/Natural_gas_liquids

Crude oil refining is a key transformation step in the

Midstream Sector of the oil and gas value chain

because it adds commercial value to the oil by

transforming it into many different marketable

products.



GLOBAL ECONOMY

DEPENDS ON ENERGY The global economy receives almost 80% of its

energy subsidies from nonrenewable fossil sources:

crude oil, gas, and coal.

They are called "nonrenewable" because, for all

practical purposes, they're not being made any more.

Nonrenewable fossil sources are the major

contributors to global warming


DIFFERENT ENERGY

SOURCES


WORLD OIL RESERVES


ECONOMY AND CRUDE OIL IN

UAE?

Crude Oil production has been the mainstay of the

economy in the UAE and will remain a major

revenue earner long into the future, due to the vast

hydrocarbon reserves at the country’s disposal.

Proven recoverable oil reserves are currently put at

98.2 billion barrels or 9.5 percent of the global

crude oil proven reserves.


CRUDE OIL

REFINERIES

Refinery: From Crude to Useful

Products



WORLD’S REFINERIES

Petroleum refineries are marvels of modern engineering.

Within them a maze of pipes, distillation columns, and

chemical reactors turn crude oil into valuable products.

Large refineries cost billions of dollars, employ several

thousand workers, operate around the clock, and occupy the

same area as several hundred football stadiums.

Useful Products from crude oil


Petroleum Refining Processes

Petroleum refining processes are the chemical engineering

processes and other facilities used in petroleum refineries

(also referred to as oil refineries) to transform crude oil into

useful products such as liquefied petroleum gas (LPG),

gasoline or petrol, jet fuel, diesel oil and fuel oils.

We will study the following processes:

Hydrodesulfuration as pretreatment

Isomerization

Reforming Catalytic

Thermal cracking

Cooking


http://www.youtube.com/watch?v=jk0WrtA8_T8


ABU DHABI REFINERY

Following the discovery of oil in Abu Dhabi in 1958, and the first export shipments of Crude in 1962, plans were drawn up for a grass root Refinery with a capacity of 15,000 barrels per stream day (BPSD) to meet a growing local need for petroleum products


CRUDE OIL FOR ABU DHABI

REFINERY

The Refinery is a Hydro Skimming

Complex designed to process Bab

Crude as well as a mixture of Asab-

Sahil, Shah and Thammama

Condensate.


REFINERY MAIN UNITS IN

ABU DHABI REFINERY Crude Distillation Unit

Naphtha Hydrodesulphuriser Unit

Kerosene Merox Unit

Catalytic Reformer Unit

Gas Oil Hydrodesulphuriser Unit

LPG Treating and Recovery Unit

Naphtha Stabilizer Unit

Gas Sweetening Unit

Sulphur Recovery Unit

REFINERY FINAL PRODUCTS



STUDY THE MARKET

BEFORE YOU DECIDE We need to study the market in order to adjust the production of each

refinery product to maximize profits

Various fractions are more important at different times of year. During the summer driving months, the public consumes vast amounts of gasoline, whereas during the winter more fuel oil is consumed.

These demands also vary depending upon whether you live in the frigid north, or the humid south.

Modern refineries are able to alter the ratios of the different fractions to meet demand, and maximize profit.


WORLD MARKETS


FROM THE WORLD MARKET DISTILLATE AND GASOLINE ARE THE TWO MOST

IMPORTANT PRODUCTS

LIGHT CRUDE OILS CAN SATISFY THE MARKET BETTER

THAN HEAVY CRUDE OILS

FROM HEAVY CRUDE OILS , CRACKING PROCESSES ARE

NEEDED TO OBTAIN SMALLER CHAINS HYDROCARBONS

AS DISTILATE AND GASOLINE

Classification of Crude

Oils

WTI or Brent

Light or Heavy

Sweet or Sour



CLASSIFICATION OF CRUDE

OILS

The oil industry classifies "crude" by the location of its origin (e.g., "West Texas Intermediate, WTI" or "Brent")

Often by its relative weight or viscosity ("light", "intermediate" or "heavy");

Refiners may also refer to it as "sweet," which means it contains relatively little sulfur, or as "sour," which means it contains substantial amounts of sulfur and requires more refining in order to meet current product specifications.

Each crude oil has unique molecular characteristics which are understood by the use of crude oil assay analysis in petroleum laboratories.

http://en.wikipedia.org/wiki/Oil_industry

http://en.wikipedia.org/wiki/API_gravity

http://en.wikipedia.org/wiki/Viscosity

http://en.wikipedia.org/wiki/Light_crude_oil

http://en.wikipedia.org/wiki/Heavy_crude_oil

http://en.wikipedia.org/wiki/Sweet_crude_oil

http://en.wikipedia.org/wiki/Sulfur

http://en.wikipedia.org/wiki/Sour_crude_oil


http://en.wikipedia.org/wiki/Crude_oil_assay

Brent Blend

Brent blend is a light crude oil (LCO), though not as

light as West Texas Intermediate (WTI). It contains

approximately 0.37% of sulphur, classifying it as

sweet crude, yet not as sweet as WTI.

Brent is suitable for production of petrol and middle

distillates. It is typically refined in Northwest Europe.

Brent Crude has an API gravity of around 38.06 and

a specific gravity of around 0.835.


WTI Crude Oil

WTI is a light crude oil, with an API gravity of around

39.6 and specific gravity of about 0.827, which is

lighter than Brent crude.

It contains about 0.24% sulfur thus is rated as a sweet

crude oil (having less than 0.5% sulfur), sweeter than

Brent which has 0.37% sulfur.

WTI is refined mostly in the Midwest and Gulf Coast

regions in the U.S.



HYDROCARBONS IN

CRUDE OILS

COMPOSITION OF PETROLEUM

(PAGES 62-64)


BASICS OF HYDROCARBON

CHEMISTRY

Crude oil is a mixture of hydrocarbon molecules, which are organic compounds of carbon and hydrogen atoms that may include from one to 60 carbon atoms.

The properties of hydrocarbons depend on the number and arrangement of the carbon and hydrogen atoms in the molecules.

Hydrocarbons containing up to four carbon atoms are usually gases, those with 5 to 19 carbon atoms are usually liquids, and those with 20 or more are solids.


THE MAIN HYDROCARBONS

OF CRUDE OILS Paraffins

Aromatics

Naphtenes

Other hydrocarbons:

Alkenes

Dienes and Alkynes


PARAFFINS

The paraffinic series of hydrocarbon compounds found in

crude oil have the general formula CnH2n+2 and can be

either straight chains (normal) or branched chains

(isomers) of carbon atoms.

Examples of straight-chain molecules are methane,

ethane, propane, and butane (gases containing from one

to four carbon atoms), and pentane and hexane (liquids

with five to six carbon atoms).


THE SIMPLEST PARAFFIN

METHANE


C4H10

BUTANE AND ISOBUTANE


AROMATICS

Aromatics are unsaturated ring-type (cyclic) compounds which react readily because they have carbon atoms that are deficient in hydrogen.

All aromatics have at least one benzene ring (a single-ring compound characterized by three double bonds alternating with three single bonds between six carbon atoms) as part of their molecular structure.

Naphthalenes are fused double-ring aromatic compounds.

The most complex aromatics, polynuclears (three or more fused aromatic rings), are found in heavier fractions of crude oil.


AROMATIC COMPOUND

BENZENE (C6H6 )


DOUBLE-RING AROMATIC

COMPOUND

NAPTHALENE (C10 H8)


NAPHTHENES

(monocycloparaffins)

Naphthenes are saturated hydrocarbon groupings with the general formula CnH2n , arranged in the form of closed rings (cyclic) and found in all fractions of crude oil except the very lightest.

Single-ring naphthenes (monocycloparaffins) with five and six carbon atoms predominate, with two-ring naphthenes (dicycloparaffins) found in the heavier ends of naphtha.

CLASSIFICATION OF

CRUDE OILS



CHARACTERIZATION OF

CRUDE OILS ?

Attempts have been made to use

Distillation ranges in order to classify

crude oils as :

Paraffinic

Naphtenic

Aromatic


CRUDE OILS ARE DEFINED AS :

Paraffin base

Naphtene base

Asphalt base

Mixed based

Aromatic base ( up to 80% aromatics)


CRUDE OIL CLASSIFICATION

in order of decreasing value

1) PARAFFINIC CRUDE OILS

paraffins + naphthenes > 50%

paraffins > naphthenes

paraffins > 40%

2) NAPHTHENIC CRUDE OILS

2) paraffins + naphthenes > 50%

naphthenes > paraffins

naphthenes > 40%




3) PARAFFINIC- NAPHTENIC CRUDE OILS

Aromatics < 50%

paraffins < 40%

naphthenes < 40%

4) AROMATIC- NAPHTENIC CRUDE OILS:

Aromatics > 50%

naphthenes > 25%

paraffins < 10%




5)AROMATIC- INTERMEDIATE CRUDE OILS

Aromatics > 50%

paraffins > 10%

6)AROMATIC- ASPHALTIC CRUDE OILS

naphthenes > 25%

paraffins < 10%


PROBLEMS WITH HEAVY CRUDE

OILS

The heavier a crude oil is, the more difficult a challenge it presents in extracting it from the ground and purifying it into end products.

Crude oil's physical properties, such as viscosity, and its chemical impurities affect the cost of recovery and refining, and the amount of waste produced in processing.

New air-pollution regulations have tightened the restrictions on the amount of impurities, such as sulfur, that can remain in petroleum products used as fuel.


HEAVY CRUDE OILS

SITUATION IN THE MARKET

So, oil companies have focused on bringing up the

lighter oil and leaving denser oil under ground.

Moreover, due to increased refining costs and high

sulfur content, heavy crude oils are often priced at a

discount to lighter ones.

http://en.wikipedia.org/wiki/Refining


LIGHT CRUDE OILS AND

GLOBAL MARKET

But industry predictions show that the supply of

light crude oils is dwindling, leaving an increasing

proportion of heavy grades for future use.

In fact, most of the Western Hemisphere's

remaining oil is heavy crude, creating a strong

strategic incentive to find new ways to extract and

use it.


COST INVOLVED FOR

HEAVY CRUDE OILS

The increased viscosity and density also makes

production more difficult.

Large quantities of heavy crude oils have been

discovered in the Americas including Canada,

Venezuela and Northern California.

The relatively shallow depth of heavy oil fields

(often less than 3000 feet) contributes to low

drilling costs.

http://en.wikipedia.org/wiki/Canada

http://en.wikipedia.org/wiki/Venezuela

http://en.wikipedia.org/wiki/Northern_California

http://en.wikipedia.org/wiki/Oil_well


PROPERTIES OF HEAVY

CRUDE OILS

Heavy crude oil is asphaltic. It is "heavy" (dense and

viscous).

heavy crude oils with a high content of naphthenic

compounds, such as asphaltenes.

Asphaltic crude oils are also known as naphthene-

based crude oil when the paraffin wax content is low (

< 10%)

Heavy oil has over 60 carbon atoms and hence a high

boiling point and molecular weight.

http://en.wikipedia.org/wiki/Asphalt

http://www.glossary.oilfield.slb.com/Display.cfm?Term=asphaltenes

http://www.glossary.oilfield.slb.com/Display.cfm?Term=paraffin


ENVIRONMENTAL ISSUE OF

HEAVY CRUDE OILS

As a rule, heavy crude oils have a more severe

environmental impact than light ones.

Heavy crude oils also carry contaminants. For example,

Orinoco extra heavy oil contains 3.5% sulfur as well as

vanadium and nickel

Heavy crude oils contain more carbon in relation to

hydrogen, thus releasing more CO2 (believed to be

responsible for climate change) per amount of usable

energy when burned.


http://en.wikipedia.org/wiki/Vanadium

http://en.wikipedia.org/wiki/Nickel


CHARACTERIZATION OF

CRUDE OIL

PROPERTIES/ASSAY

Pages 57-70


WHY CHARACTERIZE

CRUDE OILS ?

Crude grades vary considerably from each other - in yield

and properties.

Crude characterization is essential to estimate:

Feedstock properties for refinery units,

Produce an optimal amount of final products

Meet product quality specifications

Provide an economic assessment for crude oils.


CRUDE CHARACTERIZATION

IS UTILIZED BY: UPSTREAM PLANNING

To determine the economic viability of new fields / discoveries

SUPPLY ORGANIZATIONS

To assign crude value for individual grades

REFINERY OPERATIONS

To schedule crude receipts and determine product yields

MODEL ENGINEERS

To optimize refinery crude slates

RESEARCH & DEVELOPMENT

To design equipment and process planning


HOW TO CHARACTERIZE

CRUDE OILS

Because crude oils contain hundreds of

hydrocarbons and therefore exact composition of

crude oils is unknown

We need other methods to characterize crude oils

Properties of crude oils are then defined by

different assay.


WHAT IS A CRUDE OIL ASSAY?

An efficient assay is derived from a series of test data is then used to give an accurate description of crude oil quality.

These properties allow an indication of crude oil behavior during the refining processes


THE IMPORTANCE OF CRUDE

OIL ASSAYS

Knowing what your crude is worth begins by

having good crude assay data.

The identification of chemical and physical

properties of crude oil provides the basis for

economic valuation, engineering design and

refinery processing.


THE MOST IMPORTANT ASSAY

Density or API Gravity

Distillation range

Characterization Factor

Pour point

Carbon residue

IMPURITIES :

Sulfur Content

Salt content

Nitrogen Content


SPECIFIC GRAVITY OF

CRUDE OIL


DEFINITION OF DENSITY

Density ( ASTM D-1298, IP 160) is an important property used to determine the quality of crude oils

Petroleum and petroleum products are usually bought or sold on the density basis

Definition: Density of a crude oil is the mass of oil by unit volume at 150C

In laboratories, hydrometers, pycnometers or modern digital density meter are used to measure specific gravity


CRUDE OIL’S API GRAVITY

Crude oils are defined in terms of API (American

Petroleum Institute) gravity.

The higher the API gravity, the lighter the crude.

Crude oils API gravity may range from less than

100API to over 500 API but most crude oils fall in

the 20 to 450 API


WHAT IS 0API?

°API of different crude oils Light crude oil is defined as having an API gravity higher than

31.1 °API (less than 870 kg/m3)

Medium crude oil is defined as having an API gravity between

22.3 °API and 31.1 °API (870 to 920 kg/m3)

Heavy crude oil is defined as having an API gravity below 22.3

°API (920 to 1000 kg/m3)

Extra heavy crude oil is defined with API gravity below 10.0

°API (greater than 1000 kg/m3)



API DENSITY AND TYPE OF

HYDROCARBONS

Crude oils with low carbon, high hydrogen, and high API gravity are usually rich in paraffins and tend to yield greater proportions of gasoline and light petroleum products VALUABLE CRUDE OIL

Those with high carbon, low hydrogen, and low API gravities are usually rich in aromatics and more impurities LESS VALUABLE CRUDE OIL


True Boiling Point or TBP

Curve

DISTILLATION TEST


TRUE BOILING POINT ( TBP)

A Distillation Curve

A plot of the boiling points ( temperatures) of crude oil versus % volume of distilled fractions

TBP crude oil distillations by ASTM D 5236


TBP OF CRUDE OIL IS A KEY

ASSAY FOR REFINERIES

A full and comprehensive evaluation of the crude

starts with a True Boiling Point Distillation

The distillation test is a method used to give an

indication of the types of the products that can be

obtained by the crude oils

A boiling range of the crude oil gives an indication of

the quantities of the various products present

LISTEN...LEARN...THINK...GROW67

CRUDE OIL TBP ASSAY IN

OUR LAB


RESULT OF THE EXPERIMENT:

TRUE BOILING CURVE OF CRUDE OIL


ATMOSPHERIS AND VACUUM

DISTILLATION

ASTM D-86 ( Atmospheric distillation):

This test is carried out at atmospheric pressure and is

stopped at 3000C ( 5720F) to avoid thermal cracking

ASTM D-1160 (Vacuum distillation):

This test method covers the determination, at reduced

pressure, of the boiling temperature ranges of

petroleum products from the residue of the atmospheric

distillation.


DISTILLATION LABS

ATMOSPHERIC AND VACCUM

DISTILLATIONS


LAB for atmospheric distillation

ASTM D-86 ( Atmospheric Distillation):


LAB for Vacuum distillation

ASTM D-1160 (Vacuum distillation):


DISTILLATION RANGES FOR

REFINERY PRODUCTSATMOSPHERIC DISTILLATION PRODUCTS

Butanes and lighter 55-175 0F-

Light Gasoline 175-300 0F

Light naphtha 300-400 0F

Heavy naphtha 400-500 0F

Kerosene 500-650 0F

Atmosphere Gas Oil 650-800 0F

VACUUM DISTILLATION PRODUCTS

Light Vacuum Gas Oil (LVGO) 800-1000 0F

Heavy. Vacuum Gas Oil (HVGO) 1000 0F

Vacuum Residue > 1000 0F

Measuring the Density of

different fractions



0API VERSUS % VOLUME

DISTILLED FRACTION


ASSAY TO DETERMINE

GASES IN CRUDE OILS

BY GAS CHROMATOGRAPHY


LIGHT HYDROCARBONS OR

GASES IN CRUDE OILS

The amount of the individual light

hydrocarbons in crude oils ( methane to butane)

is often included as part of a preliminary assay

The identification and quantification of each

light component is carried out by GC or gas

chromatography ( ASTM D-2427)


CLASS WORK #1

Study appendix C ( page 415)

about the specifications of

different crude oils

Group discussion


CLASS WORK #2

Study the data of the crude oil given in figure 3.5 page 66:

1) Define its type knowing its density

Draw the TBP curve ( Temperature versus the percentage distilled using figure 3.6 page 67 for the products of vacuum distillation)

Draw the API curve ( 0 API versus the percentage distilled)

Perform an approximate material balances of the refinery using this crude oil using the typical ranges of refinery products (given above).


CHARACTERIZATION

OF CRUDE OILS


THE NEED FOR

CHARACTERIZATION FACTORS

Problems arise at ranges above 2000C, since molecules can not be placed in one group ( naphthenic/ aromatic or cyclic/ paraffinic)

To overcome this situation, characterization factors based on specific gravity and TBP distillation were introduced to characterize the different crude oils


CHARACTERIZATION OF

CRUDE OILS

The two mostly used correlations between yield

and aromaticity and paraffinicity of crude oils are:

UOP or Watson Characterization factor

( KW)

US bureau of Mines Correlation index

(CI)


WATSON CHARACTERIZATION

TB is the average boiling point in 0R

S.G is the specific gravity at 600F

KW ranges from less than 10 for highly aromatic crude oils to almost 15 for highly paraffinic crude oils

KW ranges 10.5-12.5 for highly naphtenic (Cyclic) crude oils and 12.5 -13 for highly paraffinic crude oils

GS

TK B

W.

3/1

84

CORRELATION INDEX (CI) THE CORRELATION INDEX ( CI) IS BASED ON THE PLOT OF SPECIFIC

GRAVITY VS THE RECIPROCAL OF THE BOILING POINT IN

S.G is the specific gravity at 600F

the CI is useful for individual fractions ( PRODUCTS)

CI is based on straight paraffins having CI = 0 and benzene having CI =100

Low CI ( 0-15) indicates great concentration of paraffins in the fraction

Average CI ( 15-50) indicate a predominance of naphthenes or a mixture of paraffins, naphthenes and aromatics

High CI ( above 50) indicates great concentration of aromatics

8.456.7.47387552

GxST

CIB

CLASS WORK

Solve problems 1, 2 and 3 page 68



KINEMATIC

VISCOSITY


DEFINITION

Viscosity is a measure of the resistance of a

fluid to deform under shear stress.

It is commonly perceived as "thickness", or

resistance to flow.

Viscosity describes a fluid's internal resistance to

flow and may be thought of as a measure of fluid

friction.

http://en.wikipedia.org/wiki/Drag_%28physics%29

http://en.wikipedia.org/wiki/Fluid

http://en.wikipedia.org/wiki/Shear_stress

http://en.wikipedia.org/wiki/Friction


KINEMATIC VISCOSITY

In many situations, we are concerned with the ratio of the viscous force to the inertial force, the latter characterized by the fluid densityρ.

This ratio is characterized by the kinematic viscosity (ν), defined as follows:

ν =μ/ρ

.

where η is the dynamic viscosity, and ρ is the density.

Kinematic viscosity (Greek symbol: ν) has SI units (m²·s-1).

It is sometimes expressed in terms of centistokes (cS or cSt). In U.S. usage, stoke is sometimes used as the singular form.

1 stokes = 100 centistokes = 1 cm2·s−1 = 0.0001 m2·s−1.

1 centistokes = 1 mm²/s

http://en.wikipedia.org/wiki/Inertia

http://en.wikipedia.org/wiki/Fluid

http://en.wikipedia.org/wiki/Density


KINEMATIC VISCOSITY OF

CRUDE OILS

Kinematic viscosity is usually

determined at 250C ( 770F) and 1000C

(2120F) by measuring the time for a

volume of liquid to flow under gravity

through a calibrated glass capillary

viscometer ( ASTM D-445)


WHY KINEMATIC VISCOSITY OF

CRUDE OILS IS IMPORTANT

Cost of exploitation and transportation of

crude oils depends on its kinematic

viscosity

Light crude oils have small kinematic

viscosity and then transportation cost are

low


HIGH VISCOSITY OF VENEZUELA

AND CANADIAN CRUDE OILS

For example, the viscosity of Venezuela's

Orinoco extra-heavy crude oil lies in the range

1000-5000 cP.

Canadian extra-heavy crude has a viscosity in

the range 5000-10,000 cP.


http://en.wikipedia.org/wiki/Poise


LAB #4 ( KINEMATIC

VISCOSITY)


POUR POINT


DEFINITION OF POUR

POINT

The pour point of a liquid is the lowest temperature at which it will pour or flow under prescribed conditions. It is a rough indication of the lowest temperature at which oil is readily pumpable.

Also, the pour point can be defined as the minimum temperature of a liquid, particularly a lubricant, after which, on decreasing the temperature, the liquid ceases to flow.

http://www.answers.com/topic/liquid

http://www.answers.com/topic/temperature

http://www.answers.com/topic/oil

http://www.answers.com/topic/temperature

http://www.answers.com/topic/lubricant


CRUDE OILS BEHAVIOR AT

LOW TEMPERATURES

Viscosity and Pour point determinations are

performed to give us information about flow

characteristics of crude oils at low

temperatures

Some general information about the type of

crude oil can be derived from its pour point

data


POUR POINT OF CRUDE

OILS

The Pour point of crude oil is indicate the lowest temperature at which the crude oil will flow under specific conditions

The maximum and the minimum Pour points temperatures provide the range of temperatures in which the crude oil might appear in liquid form as well as in solid form


POUR POINT OF CRUDE

OILS

Pour Point of crude oil is the temperature at which

the oil no longer flows when tilted in a test jar; the

liquid phase is trapped within the PARAFFIN

CRYSTAL STRUCTURE

The paraffins are the first components to crystallize

under low temperatures


PROBLEMS RELATED TO

POUR POINTS

The production and transportation of

crude oil and its fractions can be

significantly affected by deposition of

paraffin and asphaltenes in the reservoir

rock tubulars, pumps, vessels, and

pipelines.


ADDITIVES FOR

CRYSTALLIZATION PROBLEMS The Pour point is also used to screen the effects of wax

interactions modifiers on the flow behavior of the crude oil

In a gas-oil NON-FLOW CONDITIONS happen at about

1% crystallization

whereas in a crude oil this happens at 2% crystallization.

The additives used to achieve this are usually referred to

as Pour Point Depressants or PPD’s.


LAB # 6 ( POUR POINT)


CARBON RESIDUE


CARBON RESIDUE

The Carbon residue is roughly related to the

asphalt of the crude oil and to the quantity of the

lubricating oil fraction that can be converted

Determined by distillation to a coke residue in the

absence of air

The lower the Carbon Residue, the more

valuable is the crude


CARBON=POISON TO

CATALYSTS

Carbon residue cause rapid deactivation of

catalysts and high catalysts cost

For ARC feeds, we use catalytic processes

For VRC, we use non-catalytic processes


CRUDE OIL

IMPURITIES


INTRODUCTION

Crude oil is a dense, dark fluid

containing many varieties of complex

hydrocarbon molecules, along with

organic impurities containing sulfur,

nitrogen, and heavy metals.


SULFUR COMPOUNDS IN

HEAVY CRUDE OILS

Hydrogen sulfide (H2S),

Compounds (e.g. mercaptans, sulfides, disulfides,

thiophenes, aphthenes, etc.

Elemental sulfur


SULFUR REFINERY

PROBLEMS

Sulfur presence in crude oil is detrimental to the processing because sulfur can act as catalyst poisons during processing

Compounds containing sulfur cause also equipment corrosion and atmospheric pollution when products are burned

The sulfur content in crude oil varies from 0.1% to 3% weight and a sulfur content up to 8% was found in tar sand bitumen


SULFUR IN CRUDE OILS

Crude oils with less than 0.5% of sulfur are called sweetcrude oil and the crude oils with more than 0.5% are called sour crude oils

Sour crude oils require special processing and are then less expensive than the sweet crude oils

One of the most used technique to evaluate the percentage of sulfur is the combustion of a sample in oxygen to convert sulfur to sulfur dioxide which is titrated iodometrically or detected by nondipersive infrared ( astm D-1552)


OXYGEN COMPOUNDS

Oxygen compounds such as phenols,

ketones, and carboxylic acids occur in crude

oils in varying amounts

Nitrogen is found in lighter fractions of crude

oil and more often in heavier fractions of crude

oil as non- basic compounds


NITROGEN CONTENT

A high nitrogen content is undesirable in crude

oils before organic nitrogen compounds cause

severe poisoning of catalysts and corrosion of

equipments

Crude oils containing nitrogen above 0.25% by

weight require special processing to remove

the nitrogen


METAL CONTENT ( PPM)

Metals found in crude oils come from the reservoir itself but also during recovery, transportation and storage.

Even traces of metals can be deleterious to processes using catalysts but can also cause corrosion and affect the quality of products

Trace Metals. Metals, including nickel, iron, and vanadium are often found in crude oils in small quantities

Test methods such as Atomic Absorption Spectrometry, X-ray fluorescence spectroscopy are used to determine the amounts of metals


SALTS IN CRUDE OILS

Salts. Crude oils often contain inorganic salts such as sodium

chloride, magnesium chloride, and calcium chloride in

suspension or dissolved in entrained water (brine).

Salts in crude oils come mostly from production practices used

in the field but at some extent from handling to tankers bringing

it to terminals

Most of the salts are dissolved with coexisting water and

removed in desalters but some can be dissolved in the crude oil

itself


SALTS CONTENT

Salts can accumulate in stills, heaters and

exchangers leading to fouling that requires expensive

clean up.

Salts content can be determined by potentiometric

titration

The amount of salts in crude oils is important to

decide whether and to what extent the crude oil needs

desalting


OTHER IMPURITIES WITH

SMALLER AMOUNTS

Carbon Dioxide

Naphthenic Acids: Some crude oils

contain naphthenic (organic) acids


CONCLUSION ON CRUDE

OILS PROPERTIES

API Gravity: oAPI defined asoAPI= (141.5/ sp.gr.) -131.5

Most crude oils fall in the 20-45 0API range ( the reference temperature is 600F ( 15.60C)

TBP Curve

Sulfur Content ( wt%)

Sulfur content can be from 0.1% to 5%

More than 0.5%, crude are sour and need special processing


INTERPRETATION OF

PROPERTIES

Pour point: Low pour point means lower paraffin and the greater the content of aromatics

Carbon Residue ( wt%): Related to asphalt content and to the quantity of the lubricating oil that could be recovered

Salt Content ( lb/ 1000bbl): If the salt content , when expressed as NaCl, is greater than 10 lb/ 1000bbl ( 30 ppm), it is necessary to desalt the crude in order to avoid corrosion


MAJOR REFINERY PRODUCTS

DUE TO THE ACTUAL MARKET

LPG

Gasoline

Jet fuels

Diesel fuels

Home heating oils


SPECIFICATIONS OF

REFINERY FINAL

PRODUCTS


WHAT IS LPG?

Varieties of LPG bought and sold include mixes that are primarily propane, mixes that are primarily butane, and the more common, mixes including both propane (60%) and butane(40%).

Depending on the season—in winter more propane, in summer more butane.

Propylene and butylenes are usually also present in small concentration.

A powerful odorant, ethanethiol, is added so that leaks can be detected easily

http://en.wikipedia.org/wiki/Propane

http://en.wikipedia.org/wiki/Butane

http://en.wikipedia.org/wiki/Propane

http://en.wikipedia.org/wiki/Butane

http://en.wikipedia.org/wiki/Propylene

http://en.wikipedia.org/wiki/Butylene

http://en.wikipedia.org/wiki/Ethanethiol


SECURITY FOR LPG

STORAGE IN REFINERIES Large, spherical LPG containers may have up to a

15 cm steel wall thickness.

Ordinarily, they are equipped with an approved pressure relief valve on the top, in the centre.

One of the main dangers is that accidental spills of hydrocarbons may ignite and heat an LPG container, which increases its temperature and pressure, following the basic gas laws.

The relief valve on the top is designed to vent off excess pressure in order to prevent the rupture of the tank itself

http://en.wikipedia.org/wiki/Valve

http://en.wikipedia.org/wiki/Hydrocarbon

http://en.wikipedia.org/wiki/Gas_laws


STORAGE OF COMMERCIAL

PROPANE AND BUTANE FOR

HOMES


SECURITY FOR BOTTLES In order to allow for thermal expansion of the contained

liquid, these bottles are not filled completely; typically, they are filled to between 80% and 85% of their capacity.

Vapor pressure of LPG is approximately 220 kilopascals(2.2 bar) for pure butane at 20 °C (68 °F), and approximately 2.2 megapascals (22 bar) for pure propane at 55 °C (131 °F).

LPG is heavier than air, and thus will flow along floors and tend to settle in low spots, such as basements. This can cause ignition or suffocation hazards if not dealt with.

http://en.wikipedia.org/wiki/Thermal_expansion

http://en.wikipedia.org/wiki/Kilopascal

http://en.wikipedia.org/wiki/Bar_%28unit%29

http://en.wikipedia.org/wiki/Megapascal


MAIN USE OF LPG:

HEATING AND ENGINES


PROPERTIES OF

COMMERCIAL PROPANE Vapor pressure ( PSIG)

700F = 124

1300F = 286

S.G liquid (60/600F) = 0.509

Limits of flammability (vol% gas in air)

Lower limit = 2.4

Upper limit = 9.6

Gross heating values:

Btu/ft3 gas = 2,560


PROPERTIES OF

COMMERCIAL BUTANE

Vapor pressure ( PSIG)

700F = 31

1300F = 97

S.G liquid (60/600F) = 0.582

Limits of flammability (vol% gas in air)

Lower limit = 1.9

Upper limit = 8.6

Gross heating values:

Btu/ft3 gas = 3,350


Motor gasoline characteristics: The critical properties are:

* Ried vapor pressure ( RVP): Vapor pressure is a measure of the surface pressure it takes to keep the liquid from vaporizing. RVP is measured at 100oF

* RVP of gasoline must meet two conditions:

- On cold start , enough gasoline must vaporize to provide ignitable mixture

- On hot restart, the gasoline should not expand in the injection apparatus and must let air to come in

* Boiling range ( 100 -4000F)

* Antiknock characteristics: PON

* Desirable sulfur content is < 300 PPM


Octane number?

Definition: A value used to indicate the resistance of a motor fuel to knock. Octane numbers are based on a scale on which isooctane is 100 (minimal knock) and heptane is 0 (bad knock).

Example: A gasoline with an octane number of 92 has the same knock as a mixture of 92% isooctane and 8% heptane.

We can measure antiknock by using the octane number :

PON: posted octane number

MON: motor octane number

RON : research octane number

Antiknock performance is the main difference between the grades of gasoline


Posted Method Octane

number

Gasoline pumps typically post octane numbers as an average of two different values. Often you may see the octane rating quoted as PON=(RON+MON)/2.

One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm ( performance inside cities).

The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm ( performance in high ways).

If, for example, a gasoline has an RON of 98 and a MON of 90, then the posted octane number would be the average of the two values or PON= 94.


CLASS WORK

WORK EXAMPLE 10.3.1 PAGE 216

DISTILLATE FUELS

Jet fuel

Diesel fuel

Heating fuels


WHAT IS JET FUEL? The most expensive distillate fuel

Used for commercial aviation and military aircraft

Known also as turbine fuels

Primary fraction of jet fuel blending is the kerosene fraction from Atmospheric distillation

Characteristics:

The most important characteristic: No freezing in the cold temperatures of the skies ( -500C)

LAB ABOUT FREEZING POINT OF FUELS

Smoke point expressed in mm of flame height at which smoke is detected ( environment)

Volume percent of total aromatics less than 20% and naphthalene less than 3%

CLASS WORK

Study the different specifications of the jet fuels in

table 2-8 page 52


WHAT IS AUTOMOTIVE

DIESEL FUEL?

Used for high speed engines such as trucks and buses

Boiling range : 360-6000F (182-3160C)

Critical properties are : volatility, viscosity, ignition quality, sulfur content, percent of aromatics and cloud point.

The cloud point of a fuel is the temperature at which the fuel becomes hazy or cloudy because of the appearance of wax crystals

Ignition properties are expressed as CETANE NUMBER


CETANE NUMBER?

Comparable to the octane number for gasoline.

A rating on a scale used to indicate the tendency of a fuel for diesel engines to cause knock.

The rating is comparing the fuel’s performance in a standard engine with that of a mixture of cetane ( HIGH IGNITION QUALITYCN=100) and alpha-methyl-naphthalene ( LOW IGNITION QUALITYCN=0).

The cetane number is the percentage by volume of cetane in the mixture that has the same performance as the fuel being tested.


WHAT IS A HEATING OIL?

Fuel oils No1 and No2:

Fuel oil No1 is similar to kerosene (Jet Fuel) but generally has a:

* higher pour point ( Defined as 50F higher than the temperature at which a liquid stops flowing)

*higher end point ( Defined as the lowest temperature at which virtually 100% of a product will boil off to vapor form)


WHAT IS FUEL OIL N02

Similar to diesel fuel

Blended from naphtha, kerosene, diesel, and

cracked gas oil

Critical properties are sulfur content, pour point,

distillation and flash point


WHAT IS RESIDUAL FUEL OIL ?

Composed of the heaviest part of crude oil and is

generally from bottoms of vacuum distillation

The critical properties are viscosity and sulfur content

Used in furnaces

CLASS WORK

tudy the different characteristics of the fuel oils in

table 2-9 page 54


REFINERY PROCESSES

Step I : Pretreatment

Step II Separations

Step III : Chemical transformation


CLASS WORK :

STUDY FIGURE 1.1 PAGE 3


CRUDE OIL

PRETREATMENT

DESALTING


INTRODUCTION Historically, the main problems associated with salt in crude oil

were corrosion and fouling in the crude unit overheads.

As downstream treatment and conversion processes assume

an ever greater importance in refinery economics and

operations, sodium poisoning of catalysts and fouling in

downstream units become increasing concerns.

Many refiners are turning to desalter upgrades and expansions

to solve the problem at source


PROBLEMS CAUSED BY THE

PRESENCE OF SALTS The salts that are most frequently present in crude oil

are calcium, sodium and magnesium chlorides.

Technical problems:

Sand, silts and salt cause deposits and foul heat exchangers.

The high temperatures that occur downstream in the process could cause water hydrolysis, which in turn allows the formation of corrosive hydrochloric acid

Sodium, arsenic and other metals can poison catalysts


CRUDE OIL DESALTING

A desalter is a process unit in an oil refinery that removes salt from the crude oil. The salt is dissolved in the water in the crude oil, not in the crude oil itself.

The desalting is usually the first process in crude oil refining. The salt content after the desalter is usually measured in PTB - pounds of salt per thousand barrels of crude oil.

Usually desalting is necessary only when the salt content of a crude oil is greater than 10 lb/ 1000bbl (expressed as NaCl)

But now almost all crude oils are desalted to increase the efficiency of the refineries

Objectives of desalting

The basic principle is to wash the salt from crude oil

using water

Secondary but important function of desalting is to

remove solid particles from crude oil

These are usually fine sands, clays and soil particles

, iron oxides and iron sulfide particles from pipelines,

tanks and tankers


Electrostatic De-salter


Description of the process The dehydration process of a desalter will reduce a

portion of the free brine as it exits the vessel. A certain

quantity of brine will continue to exit as an emulsion.

Depending on the product specifications, one, two, or

three stages of desalting may be required to satisfy

the process design requirements.

Recycling reduces dilution/wash water consumption

and disposal costs of the effluents.



THE DESALTING PROCESS

Washing the crude with 3 to 10% vol. of water

at 200-3000F then separating the water

AC or DC potentials from 12,000 to 35,000 V

are used


TECHNICAL PROBLEMS OF

THE PROCESS

The salt in crude oil is dissolved or in suspended salt crystals

in water emulsified with the crude oil.

Technical problems occur in

obtaining efficient water/ oil mixing

water-wetting of suspended particles

separation of the wash water from oil

the process is affected by :

pH, gravity and viscosity of crude oil

vol. of wash water by vol. of crude oil


TYPICAL DESALTING

CONDITIONS

0API Water ( %Vol.) Temp (0F)

> 40 3-4 240-260

30 -40 4-7 260-280

< 30 7-10 280-330


CLASS WORK

Study in group the desalting process

(Figure 4.6 PAGE 80)


PREHEATING AFTER

DESALTING Following the desalter, the crude oil is further heated by exchanging heat

with some of the hot, distilled fractions and other streams. It is then heated in

a fuel-fired furnace (fired heater) to a temperature of about 398 °C and

routed into the bottom of the first distillation unit.


STEP II: DISTILLATION AS

SEPARATION PROCESS

For any refinery, the first step is to separate the crude oil

into different fractions using distillation techniques.

two distillation columns are used ( atmospheric and

vacuum)

The amount of each fraction depends on the TBP curve of

the crude oil.


STEP III: CHEMICAL AND THERMAL

PROCESSES TO PRODUCE MORE

GASOLINE

STEP II : SEPARATION

OF CRUDE OIL INTO

FRACTIONS

DISTILLATIONS

(ATM AND VACCUM)


Step II: Crude distillation

The crude atmospheric and vacuum distillations are the first majorprocessing units in any refinery.

They are used to separate the crude oils into fractions according toboiling point so that each of the processing units following will havefeedstock that meet their particular specifications.

Higher efficiencies and lower costs are achieved if the crude oilseparation is accomplished in two steps:

First by fractionating the total crude oil at essentiallyatmospheric pressure;

Then by feeding the high-boiling bottoms fraction (topped oratmospheric reduced crude) from the atmospheric still to asecond fractionator operated at a high vacuum


OVERVIEW OF THE TWO

DISTILLATION UNITS


ATMOSPHERIC AND VACUUM

DISTILLATIONS

Atmospheric distillation operates under atmospheric

pressure and a gradient of temperatures from high

temperature in the bottom to low temperature at the

top

Vacuum distillation operates at very low pressure to

avoid thermal cracking of the heavy fractions

The fractions are separated according to their boiling

point

Vacuum Distillation

The vacuum still is employed to separate the

heavier portion of the crude oil into fractions

because the high temperatures necessary to

vaporize the topped crude at atmospheric

pressure cause thermal cracking to occur, with

the resulting loss to dry gas, discoloration of

the product, and equipment fouling due to coke

formation.


CRUDE DISTILLATION UNIT

PRODUCTS

Fuel gas: The fuel gas consists mainly of methane and ethane. In some

refineries, propane in excess of LPG requirements is also included in the

fuel gas stream. This stream is also referred to as ‘‘Dry gas.’’

Wet gas: The wet gas stream contains propane and butanes as well as

methane and ethane. The propane and butanes are separated to be used

for LPG and, in the case of butanes, for gasoline blending and alkylation unit

feed.

LSR or Light Straight-Run Naphtha: The stabilized LSR naphtha (or LSR

gasoline) stream is desulfurized and used in gasoline blending or processed

in an isomerization unit to improve octane before blending into gasoline.

CRUDE DISTILLATION UNIT

PRODUCTS

HSR naphtha or HSR gasoline: The naphtha cuts are generally used ascatalytic reformer feed to produce high-octane reformate for gasolineblending and aromatics.

Gas oils: The light, atmospheric, and vacuum gas oils arm processed in ahydrocracker or catalytic cracker to produce gasoline, jet, and diesel fuels.The heavier vacuum gas oils can also be used as feedstocks for lubricatingoil processing units.

Residuum: The vacuum still bottoms can be processed in a visbreaker,coker, or deasphalting unit to produce heavy fuel oil or cracking and/or lubebase stocks. For asphalt crudes, the residuum can be processed further toproduce road and/or roofing asphalts.

Typical Boiling Ranges of typical

products of the distillation

process


PROCESS DESCRIPTION OF

ADU (Atmospheric Distillation Unit)

ADU contains around 20 fractionation trays and is equipped with one top pump around, an overhead reflux system, and three side strippers (for naphtha, kerosene, and gas oil products).

The ADU (Atmospheric Distillation Unit) separates most of the lighter end products such as gas, gasoline, naphtha, kerosene, and gas oil from the crude oil.

The bottoms of the ADU is then sent to the VDU (Vacuum Distillation Unit).


OVERVIEW OF ADU


TOP OF ADU: LPG AND

GASOLINE PRODUCTS

The condensed gasoline and water are separated

by gravity in the reflux drum. Part of the gasoline is

pumped back to the tower as reflux, with the rest

going to storage.

The water is drained to disposal and the vapor

from the ADU overhead is passed to an untreated

fuel gas system.


OVERVIEW OF THE TOP OF

ADU


NAPHTHA PRODUCT

Naphtha draw is located at tray 5.

The naphtha product flows by gravity to the top of

the naphtha stripper.

Stripping steam is used to remove the light ends,

improving the flash point.

The stripped naphtha product is pumped to storage.


KEROSENE PRODUCT

Kerosene draw is located at tray 12.

The kerosene product flows by gravity to the top of

the kerosene stripper.



The stripped kerosene product is pumped to storage.


GAS OIL PRODUCT

At tray 19, a draw pan is located from which gas oil

product is drawn.

The gas oil product flows by gravity to the top of the

gas oil stripper.



The stripped gas oil product is pumped to storage.


NAPHTHA + KEROSENE +

GAS OIL PRODUCTS


ARC :BOTTOM PRODUCT

OF ADU

The liquid part of crude oil ARC is sent for further

processing to the VDU ( Vacuum Distillation Unit).

Steam is injected into the base of the tower to reduce

the hydrocarbon partial pressure by stripping some

light boiling components from the bottoms liquid.


BOTTOM OF ADU


ATMOSPHERIC

DISTILLATION PRODUCTS

FUEL GAS C1 AND C2)

LPG (C3 and C4),

Unstabilized light naphtha,

Heavy naphtha,

Kerosene,

Gas oil

TOP (reduced) crude (ARC)


WHAT DEFINES A GOOD

SEPARATION ?

The relationship between the ASTM distillation temperatures at 95%vol and 5%vol of two adjacent fractions, light and heavy, respectively.

ASTM 5%vol T (heavy) – 95%vol T (light) = DT

(e.g., LGO) (e.g., kerosene)

IF DT > 0, called ASTM gap (good separation)

IF DT < 0, called ASTM overlap (bad separation)


FACTORS FOR A GOOD

SEPARATION

1) Number of plates

2) Reflux ratio

3) Steam injection - particularly for better separation

of heavy fractions


CLASS WORK: ADU DISTILLATION

Fractional distillation is useful for separating a mixture of substances with narrow differences in boiling points, and is the most important step in the refining process.

STUDY FIGURE 4.8 PAGE 83


SECOND DISTILLATION : VDU

OR VACUUM DISTILLATION

The VDU (Vacuum Distillation Unit)

takes the ARC from the Atmospheric

Distillation Unit bottom and separates it

into products such as vacuum gas oil,

vacuum distillate, slop wax, and residue.


OVERVIEW OF VDU


PREHEATING OF ARC

ARC is preheated by the bottoms feed

exchanger, further preheated and partially

vaporized in the feed furnace, and passed before

passing to the vacuum tower


VDU COMPONENTS

This tower contains a combination of 14 fractionation

trays.

It is equipped with three side draws and pump around

sections for

1) Vacuum Gas Oil,

2) Vacuum Distillate

3) Slop Wax products.


VDU OVERHEAD


PROCESS OF VDU

OVERHEAD

The overhead from the VDU is condensed and

combined with the vacuum steam.

The slop oil and water are separated by gravity in

the vacuum drum.

The water is drained to disposal, while the slop oil

is accumulated and occasionally drained to slop

collection.


VDU GAS OIL& DISTILLATE

&SLOP WAX PRODUCTS


VACUUM GAS OIL

PRODUCT

VGO draw is located at tray 4.

The vacuum gas oil draw tray is also a total draw

tray, where the reflux from the tray is pumped

under flow control to the tray below.

The product and pump around are cooled with the

vacuum gas oil product going to storage, while the

pump around is returned to the tower at tray 1.


VACUUM DISTILLATE

PRODUCT

The next product draw is located at tray 8, where the draw for

vacuum distillate product is located.

The vacuum distillate draw tray is a total draw tray, where the

reflux from the tray is pumped under flow control to the tray

below.

The product and pump around are cooled, with the vacuum

distillate product going to storage, while the pump around is

returned to the tower at tray 7.


VACUUM SLOP WAX

PRODUCT

At tray 14, a draw pan is located from which slop

wax product is drawn.

The slop wax product and pump around are

cooled, with the slop wax product going to

storage, while the pump around is returned to the

tower at tray 11.


VDU BOTTOM PRODUCT

The liquid from the feed furnace enters the tower

bottoms, where it is collected and sent for further

processing.

Steam is injected into the base of the tower to reduce

the hydrocarbon partial pressure by stripping some

light boiling components from the bottoms liquid.

The vapors from the feed heater enter the tower

below tray 14.


DISTILLATION

SPECIFICATIONS

AND CONTROL

CASE STUDY


EXAMPLE OF ADU

OPERATING CONDITIONS

The ADU feed is heated to 690 0F before entering

the tower which is maintained at 2.70 PSIG.

The top temperature is controlled at 280 0F which

maintains the Gasoline quality,

Draw temperatures of 355 0 F for the Naphtha, 529 0F for the Kerosene and 583 0F for the Gas Oil.

PROCESS CONTROL

SYSTEM OF ADU

DISTILLATION



CONTROL OF THE FEED

The ADU feed is pumped by P-100 (HS-100) and

controlled by FIC-100. \

It is preheated in the bottoms feed exchanger (E-

100) before entering the Feed Furnace (F-100).

TIC-100 controls the crude oil temperature

entering the ADU (T-100) by adjusting fuel gas

flow to the furnace.


CONTROL OF THE BOTTOM

OF ADU

Bottoms liquid is collected and sent to the VDU by

LIC-114 through the Bottoms Pump P-114 (HS-114).

This flow is indicated by FI-124.

Stripping steam is injected into the ADU bottoms by

FIC-134.


CONTROL OF GAS OIL

QUALITY Hot gas oil flows by gravity to the Gas Oil Stripper (T-113)

through FIC-113.

The gas oil enters the stripper at the top and flows downward over six trays.

Stripping steam is introduced into the bottom of the stripper through FIC-133.

The gas oil product is pumped from the base of the stripper by the Gas Oil Product Pump P-113 (HS-113) to storage.

The gas oil product flow is controlled by LIC-113 and the flow rate is indicated by FI-123.

The gas oil product's 95% point is monitored by AI-123.


CONTROL OF KEROSENE

QUALITY Hot kerosene flows by gravity to the Gas Oil Stripper (T-112)

through FIC-112.

The kerosene enters the stripper at the top and flows downward over six trays.


The kerosene product is pumped from the base of the stripper by the Gas Oil Product Pump P-112 (HS-112) to storage.

The gas oil product flow is controlled by LIC-112 and the flow rate is indicated by FI-122.

The kerosene product's 95% point is monitored by AI-122.


CONTROL OF NAPHTHA

QUALITY Hot naphtha flows by gravity to the Naphtha Stripper (T-111)

through FIC-111.

The naphtha enters the stripper at the top and flows downward over six trays.


The naphtha product is pumped from the base of the stripper by the Naphtha Product Pump P-111 (HS-111) to storage.

The naphtha product flow is controlled by LIC-111 and the flow rate is indicated by FI-121.

The naphtha product's 95% point is monitored by AI-121


NAPHTHA PUMP AROUND

A naphtha pump around is drawn from tray 6,

pumped through P-115 (HS-115) and controlled

by FIC-115.

The pump around return temperature is controlled

by TIC-115 which modulates cooling water flow to

E-115.


CONTROL OF GASOLINE

QUALITY The ADU overhead vapor flows through the overhead

condenser E-110 (HV-110), whose outlet temperature is indicated by TI-120, into the Overhead Reflux Drum D-111.

The hydrocarbons are partially condensed and the two phases (vapor and liquid) enter the overhead reflux drum where the condensed water separates from the hydrocarbon liquid by gravity.

The uncondensed gas (FI-130) is sent to fuel gas through PIC-120, which maintains the ADU back pressure.

Analyzers are present to monitor the C3 composition of the off gas (AI-130) and vapor pressure (AI-120) of the gasoline.

PROCESS

CONTROL OF A VDU

DISTILLATION



EXAMPLE OF VDU

OPERATING CONDITIONS

The VDU feed is heated to 750 0F before entering the

tower which is maintained at 2.00 in Hg.

The top draw temperature is controlled at 310 0F

which maintains the Vacuum Gas Oil quality

Draw temperatures of 607 0F for the Vacuum

Distillate, and 668 0F for the Slop Wax.


CONTROL OF THE VDU

FEED

The VDU feed is pumped by P-114 (HS-114)

controlled by LIC-114 and indicated by FI-124.

It is preheated by the bottoms feed exchanger E-200

before entering the Feed Furnace (F-200).

TIC-200 controls the temperature of the feed entering

the VDU (T-200) by adjusting fuel gas flow to the

furnace.


CONTROL OF VDU BOTTOM

PRODUCT QUALITY

Bottoms liquid is collected and sent to storage

through pump P-214 (HS-214), controlled by LIC-

214, and indicated by FI-224.

This residue's 95% point is monitored by AI-224.

Stripping steam is injected into the VDU bottoms by

FIC-234.


CONTROL OF SLOP WAX

QUALITY

Hot slop wax is pumped from the tower by pump P-

213 (HS-213).

The slop wax product flow to storage (FI-223) is

controlled by LIC-213, and it's 95% point is

monitored by AI-123.

Cooled pump around is controlled by FIC-213 and

returned to the tower above the slop wax draw tray.


CONTROL OF DISTILLATE

QUALITY Hot vacuum distillate is pumped from the tower by pump P-

212 (HS-212).

The vacuum distillate product flow to storage (FI-222) is controlled by LIC-212, and it's 95% point is monitored by AI-122.

Cooled pump around is controlled by FIC-212 and returned to the tower above the vacuum distillate draw tray.

Vacuum distillate reflux is controlled by FIC-232 and returned to the tower below the vacuum distillate draw tray.


CONTROL OF VGO QUALITY Hot vacuum gas oil is pumped from the tower by pump P-

211 (HS-211).

The vacuum gas oil product flow to storage (FI-221) is controlled by LIC-211, and it's 95% point is monitored by AI-121.

Cooled pump around is controlled by FIC-211 and returned to the tower above the vacuum gas oil draw tray.

Vacuum gas oil reflux is controlled by FIC-231 and returned to the tower below the vacuum gas oil draw tray.


CONTROL OF VDU

OVERHEAD

The VDU overhead vapor flows through the

overhead condenser E-210 (HV-212) into the

Overhead Vacuum Drum D-211.

The hydrocarbons are fully condensed and mixed

with the vacuum condensate flow from E-211.


CONTROL OF VACUUM IN

VDU TOP

The VDU vacuum pressure is maintained by the

steam to the vacuum ejector (HV-211), the cooling

water (HV-212) to the steam condenser E-211, and

the hydrocarbon condenser E-210.

The pressure is regulated by PIC-210, which

reduces the vacuum by circulating water to the

vacuum ejector.

CHEMICAL

TRANSFORMATION OF

HYDROCARBONS



L.O #3 :Explain the process and

principles used for hydrotreating,

catalytic reforming, and

isomerization.


OBJECTIVE OF THIS

SECTION

THE MAIN PURPOSE OF THIS

SECTION IS TO STUDY HOW A

REFINERY USE CHEMICAL

PROCESSES TO PRODUCE

GASOLINE FROM THE OTHER

FRACTIONS


CHEMICAL TRANSFORMATION

FOR ADU PRODUCTS


CHEMICAL TRANSFORMATION

FOR VDU PRODUCTS


THREE WAYS OF CHEMICAL

TRANSFORMATION

You can change one fraction into

another by one of three methods:

breaking large hydrocarbons into

smaller pieces (cracking)

combining smaller pieces to make

larger ones (unification)

rearranging various pieces to make

desired hydrocarbons (alteration)


THE NECESSITY OF THE

BREAKING PROCESSES

Very few of the components come out of

the fractional distillation columns ready

for market.

Many of them must be chemically

processed to make other fractions.

For example, only 40% of distilled crude

oil is gasoline; however, gasoline is one

of the major products made by oil

companies.


BREAKING PROCESSES

TRANSFORM HEAVIER

FRACTIONS GASOLINE

Rather than continually distilling large

quantities of crude oil, oil companies

chemically process some other

HEAVIER fractions from the distillation

column to make gasoline

This processing increases the yield of

gasoline from each barrel of crude oil.


CATALYTIC REFORMING


WHAT IS CATALYTIC REFORMING

THE MAIN PROPERTY OF GASOLINE IS HIGH OCTANE NUMBER

LOW OCTANE NUMBER GASOLINE DESTROY THE CAR ENGINE

Catalytic reforming is an important process used to convert low-octane naphtha into high-octane gasoline blending components called reformates.


FEED TREATMENT SECTION

BEFORE REFORMING

Naphtha from heavy and sour crude oils will contain some components like hydrogen sulfide, ammonia, organic nitrogen and sulfur compounds which will deactivate the Reforming catalyst

More or less standard is a feed preparation section in which, by combination of hydrotreatment and distillation, the feedstock is prepared to specification.


HYDROTREATING OF SOUR

NAPHTHA

The hydrotreater uses Co/Mn Catalyst to convert organic sulfur and nitrogen compounds into H2S and NH3

These gases are removed with the unreacted Hydrogen

The metals in the feed are retained by the hydrotreater

The hydrogen needed come from the catalytic reformer

LEAN NAPHTHA ENTERS THE CATALYTIC REFORMING SECTION


HYDROTREATING CHAPTER 9 FROM

BOOK


THE OBJECTIVE OF

CATALYTIC REFORMING

Lean naphtha is used for the production of very high concentrations of toluene, benzene, xylene, and other aromatics needed in the final product : GASOLINE

The properties of the naphtha feedstock (as measured by the paraffin, olefin, naphthene, and aromatic content) will be changed using catalysts and appropriate operating conditions.

A significant by-product, is separated from the reformate ( gasoline) for recycling and use in other processes.


PONA ANALYSIS BEFORE

AND AFTER REFORMING

Component NAPHTHA GASOLINE

* Paraffins 30-70 30-50

* Olefins 0-2 0

* Naphtenes 20-60 0-3

* Aromatics 7-20 45-60


THE CATALYTIC

REFORMING PROCESS


CATALYTIC REFORMING

PROCESS

catalytic reformer comprises a reactor section and a product-recovery section.

Naphtha feed and recycle hydrogen are mixed, heated and sent though successive reactor beds.

Each reactor needs heat input to drive the reactions

Final effluent is separated with the hydrogen being recycled or purged for hydrotreating

The reformate can be used as for gasoline blends or treated to separate aromatics components for petrochemical industries.


CATALYST AND CONDITIONS

The catalyst

A typical catalyst is a mixture of

platinum and aluminum oxide.

With a platinum catalyst, the process is

sometimes described as "platforming".

Temperature and pressure

The temperature is about 500°C, and the

pressure varies either side of 20 atm.


THE FOUR MAJOR REACTIONS

OF REFORMING

Dehydrogenation of naphtenes to

aromatics

Dehydrocyclization of paraffins to

aromatics

Isomerization

Hydrocraking


Dehydrogenation of naphtenes to

aromatics

Methylcyclohexane Toluene + 3H2

Methylcyclopentane Cyclohexane

Benzene +3H2

N-heptane Toluene + 4H2


Dehydrocyclization of paraffins

to aromatics

For example, cyclohexane, C6H14, loses

hydrogen and turns into benzene..

Heptane turns to methylbenzene or

toluene


ISOMERIZATION OF

OLEFINS AND PARAFFINS

Paraffins are isomerized and to some

extent converted to naphtenes and

naphtenes are converted to aromatics

Olefins are saturated to form Paraffins

which then react as the first step

Naphtenes are converted to aromatics

Aromatics are essentially unchanged


HYDROCRACKING

REACTIONS

Major hydrocracking reactions involve

the cracking and saturation of paraffins.

EXAMPLE: DECANE N-BUTANE


MAIN REACTIONS IN THE

FIRST REACTOR BED :

Dehydrogenation &

Dehydrocyclization Reactions:

* highly endothermic

* The temperature decreases in the

reactor

* Highest reaction rates


MAIN PROPERTY OF REACTOR

IS ITS SPACE VELOCITY (SV)

Space velocity represents the relation between volumetric flow and reactor volume.

It is often denoted by SV and it is related to the residence time in a chemical reactor, τ.

In the relationship, SV = 1/τ = volumetric flow/volume ( ex: m3/hr/m3)

The space velocity, in chemical reactor design, indicates how many reactor volumes of feed can be treated in a unit time.

For example, a reactor with a space velocity of 7 hr-1 is able to process feed equivalent to seven times the reactor volume each hour

http://en.wikipedia.org/wiki/Residence_time


AROMATICS YIELDS IN FIRST

REACTOR INCREASED BY:

High temperature ( Increases rate of

reactions)

Low pressure ( Shift chemical reaction

to the production of aromatics)

Low space velocity ( promotes approach

at equilibrium)

Low hydrogen to Hydrocarbon ratio



SECOND REACTOR BED

Isomerization Reactions

Isomerization yield is increased by:

High temperature

Low space velocity

Low Pressure

Fairly rapid reactions



THIRD REACTOR BED

Hydrocracking Reactions

Exothermic reactions and produce lighter liquid and gas products

Relatively slow reactions

Major reactions are cracking and saturation of paraffins

Hydrocracking yields are increased by:

* High Temperature

* High Pressure

* Low space velocity


Undesirable reactions In

reforming

Dealkylation of side chains on naphtenes

and aromatics to produce butane and

lighter paraffins

Cracking of paraffins and naphtenes to

form butane and lighter paraffins


Catalytic Reforming Processes

Depending upon the frequency of catalyst

regeneration, Reforming Processes are

classified as:

continuous,

cyclic

semigenerative


Continuous catalytic reforming

( figure 10.2 page 218)

Recently built reformers are continuous catalyst regeneration licensed by IFP and UOP

In this process, the catalyst flows by gravity from one reactor to another

the catalyst is then sent pneumatically to a regenerator and then sent to the first reactor

removal and replacement of catalyst during normal operation.

expensive process

the catalyst is always maintained at his highest activity.


Semiregenerative catalytic

reforming

Regeneration of catalyst occurs when:

the octane number of the gasoline becomes low

when the temperature in the reactor is close to the maximum allowable

The unit should be shut down

high hydrogen recycle rates and high pressure are used to minimize coke deposit on the catalyst

Depending on the severity of the process , the regeneration takes place every 3 to 24 months

Low capital cost


Cyclic catalytic reforming

It’s intermediate between the two

extremes

Only one reactor is shut and

regenerated when it is replaced by a

new reactor called a swing reactor

PRODUCT OF CATALYTIC

REFORMING: GASOLINE

THE MAIN PRODUCT OF ANY

REFINERY



Motor gasoline is a blend of

* Light straight line

* Catalytic Reformate

* Catalytically cracked gasoline

* Hydrocracked gasoline

* Polymer gasoline

* Additives


WHAT IS GASOLINE?

Source of energy for motors

Complex mixture of hydrocarbons with a boiling point range:100-400oF (38-205oC) by ASTM method

Grades of Gasoline: Unleaded, Regular, Premium and superpremium

CHEMICAL TANSFORMATION OF

DIFFERENT HYDROCARBONS

MAKE MORE GASOLINE FROM THE

SAME CRUDE OIL FEED RATE


THREE WAYS OF CHEMICAL

TRANSFORMATION

You can change one fraction into another

by one of three methods:

Rearranging various pieces to make

desired hydrocarbons (alteration)

Combining smaller pieces to make

larger ones (unification)

Breaking large hydrocarbons into

smaller pieces (cracking)

REARANGING THE

MOLECULAR STRUCTURE

We have studied this transformation in

the Catalytic Reforming Process where

paraffins, olefins and naphtenes were

transformed into is-paraffins or aromatics

which have highest octane number

Combining smaller pieces to make

larger ones

This transformation will be studied in this

chapter where small molecules

Alkylation Process

Isomerization process

ALKYLATION PROCESS

DEFINITION

In petroleum terminology, the term

Alkylation is used for the reaction of low

molecular weight olefins with an iso-

paraffin to form higher molecular weigh

iso -paraffin

STUDY THE ALKYLATION REACTIONS

PAGE 232 AND 233

THE ALKYLATION PROCESS

FEED:

Alkylation combines low-molecular-weight olefins (primarily a mixture of propylene and butylenes) with isobutene.

CATALYST:

Either sulfuric acid or hydrofluoric acid.

PRODUCT:

The product is called alkylate and is composed of a mixture of high-octane, branched-chain paraffinic hydrocarbons.

PRODUCT SPECIFICATIONS:

Alkylate is a premium blending stock because it has exceptional antiknock properties and is clean burning. The octane number of the alkylate depends mainly upon the kind of olefins used and upon operating conditions.

TYPICAL FEEDSTOCKS FOR

ALKYLATION PROCESS

Petroleum gas from Distillation or

cracking units

Olefins from Catalytic cracking or

hydrocracking units

Sulfuric Acid Alkylation

Process

FEED:

In cascade type sulfuric acid (H2SO4) alkylation units, the feedstock (propylene, butylene, amylene, and fresh isobutane) enters the reactor

CATALYST

the concentrated sulfuric acid catalyst (in concentrations of 85% to 95% for good operation and to minimize corrosion).

THE REACTOR

The reactor is divided into zones, with olefins fed through distributors to each zone, and the sulfuric acid and isobutanes flowing over baffles from zone to zone.

The reactor effluent is separated into hydrocarbon and acid phases in a settler, and the acid is returned to the reactor. The hydrocarbon phase is hot-water washed with caustic for pH control before being successively depropanized, deisobutanized, and debutanized.

THE PRODUCT

The alkylate obtained from the deisobutanizer can then go directly to motor-fuel blending or be rerun to produce aviation-grade blending stock. The isobutane is recycled to the feed.

SCHEMA OF THE PROCESS

PROCESS VARIABLES

REACTION TEMPERATURE

ACIDITY

ISOBUTANE CONCENTRATION

OLEFIN SPACE VELOCITY

REACTON TEMPERATURE

Normal temperatures are from 5 to 100C

Lower temperatures will increase

significantly the acid solution viscosity

Bad mixing and separation of products

Higher temperatures ( >200C)

Polymerization of olefins

ACIDITY OF SOLUTION

Highest Octane number and highest

yields are obtained at:

93-95% weight acid

1-2% water

Hydrocarbons diluents

Higher concentration of water will lower

the activity of the catalytic solution

ISOBUTANE

CONCENTRATION

Higher isobutane/olefin ratio will increase

the octane number and the yield of the

alkylate

In industrial practice the ration from 5:1

to 15:1 is used

Reactors using internal circulation use

up to 100:a to 1000:1 ratio

OLEFIN SPACE VELOCITY

Lowering the olefin space velocity or

increasing the contact time, it will:

Reduce the production of high boiling

points hydrocarbons

Increase the alkylate octane number

Contact time varies from 5 to 25 min

CORRELATON FACTOR Mrstik et al. developp a correlation factor

IE= % OF ISOBUTANE VOLUME IN REACTOR

(I/O)F= VOLUMETRIC ISOBUTANE/OLEFIN RATIO IN FEED

(SV)0= OLEFIN SPACE VELOCITY (hr-1)

NORMAL VALUES OF F : 10 TO 40

HIGHER VALUES GIVE HIGHER ALKYLATE OCTANE NUMBER

0).(100

)/.(

SV

OIIF FE

SAFETY PRECAUTIONS:

HAZARDOUS SULFURIC ACID

Loss of coolant water, which is needed to maintain process temperatures, could result in an upset.

Precautions are necessary to ensure that equipment and materials that have been in contact with acid are handled carefully and are thoroughly cleaned before they leave the process area or refinery.

..

Immersion wash vats are often provided

for neutralization of equipment that has

come into contact with hydrofluoric acid.

Hydrofluoric acid units should be

thoroughly drained and chemically

cleaned prior to turnarounds and entry to

remove all traces of iron fluoride and

hydro-fluoric acid

SAFETY PRECAUTIONS:

HAZARDUS SULFURIC ACID

Following shutdown, where water has been used the unit should be thoroughly dried before hydrofluoric acid is introduced

Leaks, spills, or releases involving hydrofluoric acid or hydrocarbons containing hydrofluoric acid can be extremely hazardous.

Care during delivery and unloading of acid is essential.

Process unit containment by curbs, drainage, and isolation so that effluent can be neutralized before release to the sewer system is considered.

Vents can be routed to soda-ash scrubbers to neutralize hydrogen fluoride gas or hydrofluoric acid vapors before release.

Pressure on the cooling water and steam side of exchangers should be kept below the minimum pressure on the acid service side to prevent water contamination.

CORROSION PROBLEMS

Some corrosion and fouling in sulfuric acid units may occur from the breakdown of sulfuric acid esters or where caustic is added for neutralization.

These esters can be removed by fresh acid treating and hot-water washing.

To prevent corrosion from hydrofluoric acid, the acid concentration inside the process unit should be maintained above 65% and moisture below 4%.

NEW UOP ALKYLATION

PROCESS

UOP has developed a new approach to produce a gasoline blending component similar in quality to traditional motor alkylate.

The InAlk process uses commercial, solid catalysts for reacting light olefins to produce a high octane, paraffinic gasoline component similar to traditional alkylate.

The InAlk process is based on proven technology and light hydrocarbon chemistry.

The Alkylene process is a novel solid-catalyst alkylation process with a product equal to that produced by liquid HF alkylation.


ISOMERIZATION PROCESS

PROCESS OBJECTIVE

ABU DHABI REFINERY : LIGHT NAPHTA AND

HEAVY NAPHTA ARE SEPARATED AND :

LIGHT NAPHTA TO ISOMERIZATION

HEAVY NAPHTA TO CATALYTIC

REFORMING

CONVERT LOW OCTANE N-PARAFFINS OF

LIGHT NAPHTA ( C4–1800F and RON ~70) TO

HIGH OCTANE ISO PARAFFINS ( RON~92) IF

RECYCLING IS USED

PROCESS TECHNIQUE

Isomerization occurs in a chloride

promoted fixed bed reactor where n-

paraffins are converted into iso-paraffins

Catalyst very sensitive to incoming

contaminants ( water and sulfur)

PROCESS STEPS

Desulfurized feed and hydrogen are dried in fixed beds of solid desiccants prior to mixing together

The mixed feed is heated and passes through a hydrogenation reactor to saturate olefins to paraffins and saturate benzene

The hydrogenation effluent is cooled and passes through a isomerization reactor

The final effluent is cooled and separated as hydrogen and LPG which go as fuel gases and isomerate product to gasoline blend.

FIGURE 10.9 PAGE 225

PROCESS VARIABLES

The yield of the process is increased by:

High temperature ( reaction rate ↑)

Low space velocity ( reaction time ↑)

Low pressure

High H2/HC Phc ↓ isomers yield ↑

GASOLINE BY CRACKING

LONG CHAIN HYDROCARBONS

CRACKING CATALYTIC

HYDROCRACKING

THERMAL CRACKING


CRACKING UNIT


Catalytic cracking?

The most important and widely used refinery

process

Convert heavy oils into valuable gasoline and

lighter products

Originally cracking was accomplished thermally

Catalytic cracking produces more gasoline with

higher octane number

Comparison between thermal and catalytic

cracking is shown in Table 6.1 page 122


PRIMARY CRACKING

REACTIONS

The primary reactions can be

represented as follow:

PARAFFIN paraffin + olefin

ALKYL NAPHTENE naphtene + olefin

ALKYL AROMATIC aromatic + olefin


HEAT OF CRACKING

REACTIONS (REACTOR)

The cracking reaction is endothermic or

exothermic?

ENDOTHERMIC

WHY?

Because we need energy to get

small molecules from big molecules


HEAT OF REGENERATION

(REGENERATOR)

The regeneration reaction is

endothermic or exothermic?

Exothermic

Why ?

Because burning coke is an

oxidation and oxidation release heat


Temperatures of reactor and

regenerator

Reactor temperature are around 900 to

10000F ( 480-5400C)

The feed temperature is around 500 to

9000F ( 260-4250C)

regeneration exit temperature is around

1200 to 15000F ( 650-8150C)


Different types of processes

Two Classes:

Moving bed

Fluidized bed

These days, there are very few

Moving bed reactors

FLUIDIZED BED?

In a Fluidized Bed Reactor, the catalyst

is distributed in the fluid phase and

behaves as a fluid.

CATALYST STAYS INSIDE THE

REACTOR


Fluid catalytic cracker

The fluid catalytic cracker (FCC) is

representative of the fluidized bed units

The FCC can be classified as :

Bed FCC

Riser FCC

Depending where the major fraction of the

cracking reactions occur


THE REACTOR AND

REGENERATOR

REACTOR

REGENERATOR


PROCESS DESCRIPTION FOR

RISER FCC:

A) FEED AND RISER:

Pre-heated feed is sprayed into the base of the riser via feed nozzles where it contacts extremely hot fluidized catalyst at 1230 to 1400 degrees F

The hot catalyst vaporizes the feed and catalyzes the cracking reactions that break down the high molecular weight oil into lighter components including LPG, gasoline, and diesel


PROCESS DESCRIPTION:

B) REACTOR AND CYCLONES:

The catalyst-hydrocarbon mixture flows upward

through the riser for just a few seconds and

then the mixture is separated via cyclones.

The catalyst-free hydrocarbons are routed to a

main fractionator for separation into fuel gas,

LPG, gasoline, light cycle oils used in diesel

and jet fuel, and heavy fuel oil.



C) STRIPPER: During the trip up the riser, the cracking catalyst is "spent" by reactions which deposit coke on the catalyst and greatly reduce activity and selectivity.

The "spent" catalyst is disengaged from the cracked hydrocarbon vapors and sent to a stripper where it is contacted with steam to remove hydrocarbons remaining in the catalyst pores



D) REGENERATOR:

The "spent" catalyst then flows into a fluidized-

bed regenerator where air (or in some cases air

plus oxygen) is used to burn off the coke to

restore catalyst activity and also provide the

necessary heat for the next reaction cycle,

cracking being an endothermic reaction.

The "regenerated" catalyst then flows to the

base of the riser, repeating the cycle

Figures 6.1 a and 6.1 b

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Endothermic_reaction


CATALYST IN FCC

The FCC uses very fine particles catalyst

( 70μm) which behave as a fluid when

aerated with vapor

The fluidized catalyst is circulated

continuously between the reactor and

the regenerator


TYPES O CATALYST

Commercial cracking catalyst can be

divide into 3 classes:

1) acid treated natural aluminosilicates

2) amorphous synthetic silica-alumina

mixtures

3) crystalline synthetic silica-alumina

catalysts called zeolites


INDUSTRIALY USED

CATALYSTS

The most commonly used are classes 2

and 3 Tables 6.2 and 6.3 PAGE 137


Advantages of zeolites catalyst

Higher activity

Higher gasoline yield

Lower coke yield


CRACKING MAIN PROBLEM:

COKING

The cracking process produces carbon which

remains on the catalyst and lowers its activity

What should we do to maintain the activity of

catalyst high?

Regenerate the catalyst by burning off the

coke with air

As a result, the catalyst is continuously

moved from reactor to regenerator

( Figure 6.1a page 95)


Catalytic hydrocracking?

A process similar to catalytic cracking in

its industrial purpose but effected under

hydrogen pressure.

The catalyst of hydrocracking containing

two functions:

A cracking function

A hydrogenating function ( Figure 7.2

page 144 shows a two-stages system).

http://64.233.183.104/C00888.pdf

http://64.233.183.104/C00876.pdf


Hydrocracking Catalyst

Most of the hydrocracking catalyst

consist of a crystalline mixture of silica

alumina with a small uniformly

distributed amount of rare earths

containing within the crystal line lattice.

The silica-alumina provides cracking

Rare earth component provides

hydrogenation


Hydrocracking and catalytic

cracking

They work as a team:

The catalytic cracker takes the more easily

cracked paraffinic atmospheric and vacuum

gas oils as charge stocks

The hydrocraking uses more aromatic

cycle oils and cooker distillates as feed.

These streams resist to catalytic cracking but

high pressure and hydrogen atmosphere make

them easy to crack


Why catalytic hydrocracking?

NEW DEMAND: The demand for petroleum products has shifted to high ratio of gasoline and jet fuel compared with the usage of diesel fuel and home heating fuels.

DISPONIBILTY OF HYDROGEN: by product hydrogen at low cost and in large amounts has become available from catalytic reforming operations

ENVIRONMENTAL CONCERNS: limiting sulfur and aromatic compounds concentrations in motor fuels have increased

PRETREATMENT OF HEAVY

DISTILLATE FRACTIONS

REMOVING IMPURITIES TO AVOID

CATALYST POISENING AND

ENVIRONMENTAL PROBLEMS

CATALYTIC PROCESS MAIN

PROBLEMS

Catalysts of Reforming catalytic &

Cracking catalytic & Hydrocracking

can be poisoned by sulfur , nitrogen

and oxygen compounds and

metallic salts present in the their

respective feedstocks


FEEDSTOCKS PREPARATION

Feed impurities are removed by a hydrotreatment process to:

Saturate the olefins

Remove sulfur, nitrogen and oxygen compounds.

Molecules containing metals are cracked and the metals are retained by the catalyst


HYDROTREATING

OBJECTIVE:

Hydrotreating is used for removing the

undesired compounds and stabilizing

the heavy distillate fractions.

Hydrotreating uses:

A catalyst

A substantial quantities of hydrogen.

ENVIRONMENTAL ISSUES

The main impurities that could also harm the environment are nitrogen and sulfur compounds.

They are removed by conversion of sulfur and nitrogen elements into ammonia and hydrogen sulfide.

Because of the new environmental regulations due to global warming, the amount of sulfur and nitrogen in the refinery products are around 50 ppm and less

MAIN HYDROTREATING

PROCESSES

The most used Hydrotreating

processes are:

Desulphurization (remove sulphur

compounds)

Denitrification (remove nitrogen

compounds)

Conversion of olefins to paraffins


HDS MAIN REACTIONS

Mercaptans: RSH + H2 RH + H2S

Sulfides : R2S + 2H2 2RH + H2S

Disulfides : (RS)2 + 3H2 2RH + 2H2S

Thiophenes :

+4H2 C4H10 + H2S

S

The reactions: EXOTHERMIC

HDS CATALYST

The most economical catalyst for HDS

is: Cobalt- Molybdene oxides on alumina


THE OTHER REACTIONS OF

THE HDS PROCESS

In the HDS reactor, other reactions take place like:

Denitrogenation

Deoxidation

Dehalogenation

Hydrogenation

Hydrocracking.

DENITROGENATION

Nitrogen is more difficult to remove than sulfur

Reactions :

Pyrrole: C4H4NH + 4H2 C4H10 + NH3

Pyridine: C5H5N + 5H2 C5H10 + NH3

For middle distillate fractions having high concentration of nitrogen, the catalyst used is : 90% Ni- Mo oxides and 10% nickel-tungsten


Operating Conditions

Temperature 270- 3400C

Pressure 690- 20,700 kPag

Hydrogen/ unit feed:

Recycling 360m3/m3

Consumption 36-142m3/m3

Space velocity 1.5 -8.0

Space velocity is defined as the rate of feed

per unit mass of catalyst ( mass of catalyst

because catalyst is very expensive)

CLASS WORK #1

Study the process of HDS figure 9-1

page 196


CLASS WORK #2:

study figure 9-2 page 199

Discuss the effects of process variables on its

efficiency:

T ↑ Removal ↑ , H2 Consumption

↑and coke ↑

PH2 ↑ Removal ↑ and H2 Consumption

↑

P ↑ H2 Consumption ↑ and Coke ↓

Space velocity ↑ Removal ↓ and H2

Consumption ↓ and Coke ↓

ACID GAS REMOVAL


ACID GAS REMOVAL

Gases from various operations of sour

crude oil contain hydrogen sulfide

The hydrogen sulfide is produced in

units such as hydrotreating, cracking and

coking

Recent air pollution regulations require

that most of the sulfur to be removed

from gases and converted to element

sulfur


THREE DIFFERENT KINDS OF

PROCESSES TO REMOVE H2S

Chemical solvent processes

Physical solvent processes

Dry adsorbents processes

Chemical solvent processes

: FIGURE 13.5

* Monoethanolamine (MEA)

* Diethanolamine (DEA)

* Methyl- Diethanolamine (MDEA)

* Diglycolamine (DGA)

* Hot Potassium Carbonate

Physical solvent processes

Physical solvent processes:

* Selexol

* Propylene Carbonate

* Sulfinol

* Rectisol

Dry adsorbents processes:

* Molecular sieve

* Activated charcoal

* Iron sponge

* Zinc oxide


Class work #3

Discuss the figure 13.5

page 284 and explain all

the steps of the process

SULFUR RECOVERY PROCESS


THE MODIFIED CLAUSS PROCESS:

The most practical method for converting

hydrogen sulfide to elementary sulfur

Best suited for gases containing more

than 50% hydrogen sulfide is the

PARTIAL COMBUSTION PROCESS.


PARTIAL COMBUSTION

PROCESS (FIGURE 13.7 PAGE

287)

Hydrogen sulfide is burned with 1/3 the

stoichiometric quantity of air

2H2S + 3O2 2H2O + 2SO2

The hot gases are sent to a reactor with

alumina as catalyst to react sulfur

dioxide with unburned hydrogen sulfide

to produce free sulfur

2H2S + SO2 2H2O + 3S

TAIL GASES OF CLAUS

PLANT

Carbon sulfide (COS) and carbon disulfide CS2

have presented problems in many Claus plant

operations.

These compounds are formed in the

combustion step ( see reactions page 289)

Unconverted, these compounds represent a

loss of sulfur recovery.

They are in the tail gas of the Claus process

and sent to the Scot process

CLASS WORK #4

USING THE BOOK, DESCRIBE ALL

THE STEPS OF THE CLAUSS

PROCESS IN FIGURE 13.7 PAGE 287


PROCESS FLOW DIAGRAM

http://en.wikipedia.org/wiki/Image:ClausPlt.JPG

http://en.wikipedia.org/wiki/Image:ClausPlt.JPG

THE SCOT PROCESS

THE TAIL GAS OF THE CLAUS

PROCESS ARE SENT TO THE SCOT

PROCESS


DESCRIPTION OF THE SCOT

PROCESS ( fig 13.9 page 291)

The tail gas of the Claus unit contains small amounts of CARBONYL SULFIDE and CARBON DISULFIDE as well as SO2 and H2S

The gas is combined with hydrogen or a mixture of ( CO + H2)

The mixture is heated at 480 to 5700F,

Pass through a catalytic reactor where sulfur compounds are converted to Hydrogen sulfide

The reactor effluent is cooled and H2S is absorbed with amine solution

The H2S from the amine generation unit is sent back to the Claus process

The H2S exiting the amine unit ( 50 to 400 ppm) is burned to produce SO2


Class work: study the process

in figure 13.9 page 291

LUBRICATING OILS

INTRODUCTION

The lube oil sold in the market are a

mixture of:

Lubricating oil base stocks

Additives

Lubricating oils

The feeds for the production of

lubricating oils come from the vacuum

distillation

The feeds are treated to improve the

quality of the lubricating oils

Chemicals are added to improve the

properties

USES OF LUBRICATING

OILS

Motor oil is a lubricant in internal combustion engines, typically found in automobiles and other vehicles, boats, lawn mowers, trains, airplanes.

In engines there are parts which move very closely against each other at high speeds, often for prolonged periods of time.

Such motion causes friction, absorbing otherwise useful power produced by the motor and converting the energy to useless heat.

Friction also wears away the contacting surfaces of those parts, which could lead to lower efficiency and degradation of the motor.

This increases fuel consumption.

http://en.wikipedia.org/wiki/Lubricant

http://en.wikipedia.org/wiki/Internal_combustion_engines

http://en.wikipedia.org/wiki/Automobile

http://en.wikipedia.org/wiki/Vehicle

http://en.wikipedia.org/wiki/Boats

http://en.wikipedia.org/wiki/Lawn_mowers

http://en.wikipedia.org/wiki/Trains

http://en.wikipedia.org/wiki/Airplanes

http://en.wikipedia.org/wiki/Friction

http://en.wikipedia.org/wiki/Motive_power

http://en.wikipedia.org/wiki/Wear

USES OF LUBRICATING

OILS

Lubricating oil makes a film between surfaces

of parts moving next to each other so as to

minimize direct contact between them

decreasing friction, wear, and production of

excessive heat, thus protecting the engine.

Motor oil also carries away heat from moving

parts, which is important because materials

tend to become softer and less abrasion-

resistant at high temperatures.

Some engines have an additional oil cooler.

http://en.wikipedia.org/wiki/Radiator

MOST IMPORTANT

PROPERTY OF MOTOR OILS

One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its viscosity

The viscosity must be high enough to maintain a satisfactory lubricating film, but low enough that the oil can flow around the engine parts satisfactorily to keep them well coated under all conditions.


VISCOSITY INDEX

The viscosity index is a measure of how

much the oil's viscosity changes as

temperature changes.

A higher viscosity index indicates the

viscosity changes less with temperature

than a lower viscosity index

http://en.wikipedia.org/wiki/Viscosity_index

POUR POINT OF MOTOR

OILS

Motor oil must be able to flow at cold winter

temperatures to lubricate internal moving parts

upon starting up the engine.

Another important property of motor oil is its

pour point, which is indicative of the lowest

temperature at which the oil could still be

poured satisfactorily.

The lower the pour point temperature of the

oil, the more desirable the oil is when starting

up at cold temperature.

FLASH POINT OF MOTOR

OILS

Oil is largely composed of hydrocarbons which can burn if ignited.

Still another important property of motor oil is its flash point, the lowest temperature at which the oil gives off vapors which can ignite.

It is dangerous for the oil in a motor to ignite and burn, so a high flash point is desirable.

At a petroleum refinery, fractional distillationseparates a motor oil fraction from other crude oil fractions, removing the volatile components which ignite more easily, and therefore increasing the oil's flash point.

http://en.wikipedia.org/wiki/Hydrocarbons

http://en.wikipedia.org/wiki/Flash_point

http://en.wikipedia.org/wiki/Oil_refinery

http://en.wikipedia.org/wiki/Fractional_distillation

TOTAL BASE/ACID NUMBER

Another test done on oil is to determine the

Total Base Number (TBN), which is a

measurement of the reserve alkalinity of an oil

to neutralize acids.

The resulting quantity is determined as mg

KOH/(gram of lubricant).

Analogously, Total Acid Number (TAN) is the

measure of a lubricant's acidity.

Other tests include zinc, phosphorus, or sulfur

content, and testing for excessive foaming.

http://en.wikipedia.org/wiki/Total_Base_Number

http://en.wikipedia.org/wiki/Alkalinity

http://en.wikipedia.org/wiki/Total_Acid_Number

http://en.wikipedia.org/wiki/Acidity

http://en.wikipedia.org/wiki/Zinc

http://en.wikipedia.org/wiki/Phosphorus


http://en.wikipedia.org/wiki/Foam


LUBRICATING OIL

BLENDING STOCKS

The main properties of lubricating oils are:

* Viscosity

* Viscosity Index

* Pour Point

* Oxidation Resistance

* Flash Point

* Boiling Temperature

* Acidity


VISCOSITY

From a given crude oil; the higher the boiling point; the greater is the viscosity

The viscosity of a lubricating oil can be selected by the distillation boiling point of the cut

Measure of internal resistance to flow

The higher is the viscosity the ticker the film of oil that clings to a surface

Depending upon the service:

* The oil should be thin and free flowing

* Or should be tick and resistant to flow


VISCOSITY INDEX (VI)

The rate of change of viscosity with temperature

The higher is the VI, the smaller is the change of viscosity with temperature

The VI of lubricating oils vary from negative values for oils from naphtenic crude oils to about 100 for oil from parrafinic crude oils.

Some specially processed oils with chemical additives can have VI higher than 130


ADDITIVES TO IMPROVE VI

Polyisobutylenes or polymethacrylic acid esters

are used to improve the VI of lubricating oils

Motor oils must be thin enough at low

temperatures to permit easy starting

Viscous enough at engine operating

temperatures ( 80-1200C) to reduce friction by

providing enough oil thickness between metal

surfaces


POUR POINT

The lowest temperature at which oil will

flow under standards conditions

A Low pour point is important in cold

days to obtain easy starting of the

engine

They are two types of pour point:

* Viscosity pour point

* Wax pour point


Viscosity pour point

The Viscosity pour point is approached

gradually as the temperature is lowered

and the viscosity of the fluid increase

until it will not flow under the standards

conditions


Wax pour point

The wax pour point occurs abruptly as

the paraffin wax crystals precipitate from

oil and the solution solidifies

Additives can be used to lower the wax

pour point


Cloud point

The cloud point is also used to report

the temperature at which wax or other

solid material begins to separate from

solution

For parrafinic oils, this is the starting

point of crystallization of parrafinic waxes


Oxidation resistance

The high temperature of engines causes the rapid oxidation of motor oils

Especially in piston heads where temperature can attain 4000C.

Oxidation causes the formation of coke

Anti oxidation additives, such as phenolic compounds , can be added to suppress oxidation


Flash point

It is only an indication of the

hydrocarbons emissions

Low flash point indicate greater

hydrocarbon emissions during use

It also indicate if a mixture of high

viscosity and low viscosity cuts or is a

central cut with average viscosity


Boiling temperature

The higher is the boiling temperature means

the higher is the molecular weights of the

components and the greater is the viscosity

The boiling ranges and the viscosities of the

fractions are the major factors in selecting the

cut points for the lube oil blending stocks on the

vacuum distillation unit.


Acidity

The organic acids formed during the oxidation of lubricating oil causes corrosion because of their acidity

The alkaline materials are added to lubricating to neutralize the acid contaminants.

Lube oils blending from parrafinic crude oils have higher oxidation stability and exhibit lower acidity than the naphtenic crude oils

LUBE OIL PROCESSINGS


LUBE OIL PROCESSING

The objective of lube oil processing is to improve the properties of raw lube oil fractions from most crude oils which contain components which have undesirable characteristics for finished lubricating oils

The heavier lube oil raw stocks are included in the vacuum fractionating tower bottoms with asphaltenes, resins, and other undesirables materials

The choice of the cut for lube

oils

The first step is the separation on the

crude oil distillation units of the individual

fractions according to viscosity and

therefore by boiling range

specifications

Heavy lube oils are produced by heavy

hydrocarbons who have high boiling

points


PROPERTIES TO BE

IMPROVED

The undesirable characteristics of these impurities include:

High Pour Point

High Cloud Point

Low VI ( large change of viscosity with Temperature)

Poor oxygen stability

Poor Color

High Organic acidity

High carbon and sludge-forming tendencies

CLASS WORK #1

STUDY AND DISCUSS WITH YOUR

FRIENDS THE MAIN PROPERTIES OF

LUBE OILS IN PAGE 309.


The processes used to change

these characteristics are:

Solvent deasphalting to reduce carbon and

sludge- forming tendencies

Solvent extraction and hydrocracking to

improve VI

Solvent dewaxing and selective hydrocracking

to lower cloud and pour point

Hydrotreating and clay treating to improve

color and oxygen stability and lower organic

acidity


PROPANE DEASPHALTING

The lighter distillate feedstocks for

producing lubricating oil base stocks can

be sent directly to the solvent extraction

unit, however the atmospheric and

vacuum still bottoms require de-

asphalting to remove the asphaltenes

and the resins before solvent extraction


QUALITIES OF PROPANE

Propane is usually used but can sometimes be mixed with ethane or butane in order to obtain desired solvent properties

Propane has unusual solvent properties:

From 40 to 600C, the paraffins are very soluble in propane but this solubility when the temperature increases until the critical temperature of propane ( 96.80C)

The asphaltens and resins are largely insoluble in propane


The Process

The feed is mixed with 4 to 8 volumes of liquid

propane at the desired temperature

The extract phase contains from 15 to 20% by

weight of oil with the remaining solvent

The heavier is the feed , the higher propane to

feed ratio

The raffinate phase contains 30 to 50%

propane by volume and is an emulsion of

precipitated asphaltic materials with propane

CLASS WORK :

STUDY AND DISCUSS WITH YOUR

FRIENDS FIGURE 15.1 PAGE 313


Viscosity Index improvement

and solvent extraction

Three solvent used for the extraction of aromatics from lube oil feeds:

Furfural

Phenol

N-methyl-2-pyrrolidone ( NMP)

The purpose of solvent extraction is to improve VI, oxidation resistance and color of the lube oil and to reduce the carbon and sledges- forming tendencies of the lubrificants by separating the aromatic portion from the naphtenic and parrafinic portions of the feed


Furfural Extraction

Similar to the propane deasphalting unit

Except: The solvent recovery which is more complicated

The extraction column is a rasching –ring packed column or sometimes a rotating disc column RDC

The temperature gradient in the column is 300C to 500C between the top and the bottom

The temperature of the top depends on the miscibility temperature of furfural and oil Usually from 1050C to 1500C


VI OF LUBE OILS IMPROVED BY

HYDROCRACKING OF GAS

OILS Table 15.1 ( page 317) shows that the VI of

mononaphtene and paraffins are high

Hydrocracking of vacuum gas oils increase the concentration of parrafins and the VI of the lube oil

When the severity of the process increases mononaphtalenes and isoparaffins increases

The good conditions of the process are :

* High conversion

* Low space velocity

* Low reaction temperature


DEWAXING

All lube oils , except those from very few naphtenic crude oils, must be dewaxed

Dewaxing is the most important process otherwise the lube oils will not flow at ambient temperatures

Two types of processes: Refrigeration to crystallize the wax and

solvent to dilute the oil fraction sufficiently to permit rapid filtration

Selective hydrocracking to crack wax molecules into light hydrocarbons


SOLVENT DEWAXING

Two principal solvents: Propane and

ketones

The ketone process uses :

* Methyl Ethyl Ketone (MEK) with

Methyl isobutyl ketone ( MIBK)

* MEK with Toluene

CLASS WORK #3

STUDY THE DEWAXING BY PROPANE

PAGE 319-320


DILCHILL DEWAXING

( Figure 15.3 PAGE 320)

Developed by EXXON

Describe Process in Figure


GRADES OF MOTOR OILS

SINGLE GRADE

MULTI GRADE

SINGLE GRADE

The Society of Automotive Engineers, usually abbreviated as SAE, has established a numerical code system for grading motor oils according to their kinematic viscosity.

For single-grade oils, the kinematic viscosity is measured at a reference temperature of 100 °C (212 °F) in units of mm²/s or the equivalent older non-SI units, centistokes (abbreviated cSt).

http://en.wikipedia.org/wiki/Society_of_Automotive_Engineers

http://en.wikipedia.org/wiki/Viscosity#Kinematic_viscosity:_.CE.BD

http://en.wikipedia.org/wiki/Stokes_%28unit%29

SINGLE SAE GRADE

The higher the viscosity, the higher the

SAE grade number is.

These numbers are often referred to as

the weight of a motor oil.

Based on the range of viscosity the oil

falls in at that temperature, the oil is

graded as an SAE number 0, 5, 10, 20,

30, 40, 50, 60 or 70.

SINGLE GRADES IN WINTER

(W)

On single-grade oils, viscosity testing can be

done at cold, winter (W) temperature (as well

as checking minimum viscosity at 100 °C or 212

°F) to grade an oil as SAE number 0W, 5W,

10W, 15W, 20W, or 25W

A single-grade oil graded at the hot temperature

is expected to test into the corresponding grade

at the winter temperature; i.e. a 10 grade oil

should correspond to a 10W oil.

MOTOR OILS WITH

ADDITIVES

A specific oil will have high viscosity when cold and a low viscosity at the engine's operating temperature.

The difference in viscosities for any single-grade oil is too large between the extremes of temperature.

To bring the difference in viscosities closer together, special polymer additives called viscosity index improvers are added to the oil.

These additives make the oil a multi-grade motor oil.

http://en.wikipedia.org/wiki/Polymer

http://en.wikipedia.org/wiki/Viscosity_index_improver

WHY MULTIGRADE LUBE

OILS

The idea is to cause the multi-grade oil to have

the viscosity of the base number when cold and

the viscosity of second number when hot.

The viscosity of a multi-grade oil still varies

logarithmically with temperature, but the slope

representing the change is lessened.

This slope representing the change with

temperature depends on the nature and amount

of the additives to the base oil.

API/SAE SCALE FOR

MLTIGRADE LUBE OILS

The API/SAE designation for multi-grade oils includes two grade numbers.

For example, 20W-50 designates a common multi-grade oil in UAE.

Historically, the first number associated with the W (again 'W' is for Winter, not Weight) is not rated at any single temperature.

The “20W" means that this oil can be pumped by your engine as well as a single-grade SAE 20 oil can be pumped.

The second number, 50, means that the viscosity of this multi-grade oil at 100 °C (212 °F) operating temperature corresponds to the viscosity of a single-grade 50 oil at same temperature




Hydrogen production &

purification

Many refineries produce enough hydrogen for hydrotreating from the catalytic reforming unit.

Some modern plants with extensive hydrotreating and hydrocracking operations require more hydrogen than they produce

This hydrogen can be produced:

-- By partial oxidation of heavy hydrocarbons such as fuels

-- By steam reforming of methane( natural gas) , ethane or propane ( FIGURE 13.1)


Steam Reforming of natural gas in

four stepsSTEP ONE: REFORMER :

CH4 + H2O CO + 3H2

Catalytic reaction

temperature range : 1400-15000F

Endothermic reaction

gas pass through a filled catalyst furnace

Catalyst: hallow cylindrical rings of ¾ in in diameter . 25 to 40% nickel oxide deposited on silica refractory base.


STEP 2 :SHIFT CONVERTER

In the shift converter, more steam is added to convert the CO produced by the REFORMER to an equivalent amount of hydrogen.

SHIFT CONVERTER: CO + H2O CO2 + H2

The shift reaction is:

* Exothermic reaction

* In fixed bed catalytic reactor

* Temperature: 6500F

* Catalyst : Mixture of chromium and iron

oxide


STEP 3 : GAS PURIFICATION

The third step is the removal of CO2 in

circulating amine or hot potassium

carbonate solution. CO2 being acid is

absorbed by a basic solution like amine

Absorption column with 24 trays


STEP 4 : METHANATION

in this last step of steam reforming, the

remaining quantities of CO and CO2 are

converted to methane :

* Exothermic Reactions:

CO + 3H2 CH4 + H2O

CO2 + 4H2 CH4 + 2H2O

* Fixed bed catalytic reactor

* Temperature range : 700-8000F

* Catalyst : 10 to 20% Ni on a refractory base


Future Trends in Petroleum

Refining There are four major forces which affect the development of petroleum refining processes:

Demand for products (i.e. gasoline or diesel, fuel oil or jet fuel ) to be cleaner and higher-performance

Feedstock supply increasing heavier and more sour crude supply — alternative feed supplies include oil sand, and coal.

Environmental regulations

Technology development (i.e. new catalysts and processes) — the development of fuel cells would drive refineries to become H2 producers

Current Government Regulations on sulfur content in diesel fuel US EPA has reduced from 5000 ppm to 500 ppm in 1993

EEC has limited to 500 ppm since 1996,

Japan has limited to 500 ppm since 1997,

Canada has limited to 500 ppm since 1998.

New US EPA Tier 2 Regualtions on sulfur content in diesel and gasoline

Most refiners must meet a 30 ppm sulfur average with a 80 ppm cap for both conventional and reformulated gasoline by January 1, 2006

New on-road diesel regulations = 15 ppm sulfur cap by January 1, 2006

New Processes for Low-Sulfur Fuels

More active and selective catalysts for existing HDS processes

Novel processing schemes that don’t depend on HDS technology

· Reactive adsorption of sulfur without high-pressure H2 (Phillips Petroleum)

Selective adsorption of sulfur compounds without H2 (PSU)

Liquid-phase oxidation followed by extraction

Bio-desulfurization that is not limited by steric restriction of 4,6-DMBT (Energy Biosystems)


GAS PROCESSING UNIT

Main objectives:

Recovery of valuable C3,C4,C5 and C6

compounds from various gas streams

generated by crude distillation, cokers, cat

crackers, reformers and hydrocrackers

Production of desulfurized dry gas

consisting mostly of methane and ethane for

use as fuel gas or feedstock for hydrogen

production


THE PROCESS (FIGURE

13.3) Compressing the gas

Feed an absorber- deethanizer unit where naphta is used to absorb 90% of the C3 and all the C4

+

The vaporized heavy hydrocarbons leave the top of the absorber with the light gases and are recovered in a sponge absorber

The non volatile kerosene can be used as sponge oil

The deethaniser rich oil will feed the debutanizer where all the propane and butane are recovered and then desulfurized and separated in a depropanizer

Natural gasoline from the bottom of the debutanizer is the feed of the naphta splitter where Light Straight Run ( C5 and C6) is produced at the top sweetened and used as gasoline blend. The lean absorbing oil is obtained at the bottom


TWO STAGES PROCESS

( Page 144)

The fresh feed is mixed with Make up and recycled Hydrogen

then pass through a heater and the first reactor ( If the feed is not treated, It should pass through a guard reactor before hydro cracking to eliminate the impurities such as organic sulfur and nitrogen compounds)

The hydrocracking reactor is operated as high temperature to convert 40 to 50% vol of the reactor effluent to material boiling below 4000F.


The reactor effluent goes through heat

exchangers and a high pressure

separator where the gas rich in hydrogen

is recycled . The liquid go to the

distillation column where light gases,

naphta and diesel are produced

The fractionator bottom is used as a

feed to the second hydrocracker


Typical hydrocracker

feedstocks

Feed Products

Kerosine Naphta

SR- Diesel Naphta , jet fuel

Atmospheric G.oil Naphta, jet fuel, diesel

Vacc. G.oil Naph, J,Fuel, Diesel, Lube oil

Light FCC cycle gas oil Naphta

Heavy FCC cycle gas oil Naphta / distillates

Light Cooker Gas oil Naphta / distillates

Heavy Cooker Gas oil Naphta / distillates


Hydrocracking Reactions

Cracking is the scission of carbon-carbon single bond

hydrogenation is the addition of hydrogen to a carbon-carbon double bond

Cracking provide double bonds for hydrogenation (page 139 and 140)

Isomerization is another reaction in hydrocracking

The olefinic products formed are rapidly hydrogenated maintaining a high concentration of high octane isoparaffins and preventing the back reactions to straight chain molecules


Hydrotreater

Number of reactions take place:

Olefin saturation

aromatic ring saturation

cracking is almost insignificant

The exothermic heats of

desulphurization and denitrogenation are

high ( 2800 kJ/std m3)


The saturation of olefins contribute also

in the exothermicity of the reaction,

However for virgin stocks, this is

negligible reaction

Reduce the water content to 25 ppm

In average, this process consume 27 to

54 m3 of hydrogen by m3 of feed)


Hydrocracking Process

Figure 7.2

Freed is mixed with recycled hydrogen

Pass trough a heater and a first reactor

If the feed was not treated , the first reactor is a guard reactor with catalyst Co-Mo on silica alumina to convert organic sulfur and nitrogen compounds to protect the hydrocracking catalyst

The hydrocracking reactor is at 660-7850F and 1000-2000 psig

The reactor effluent goes trough heat exchanger and a high pressure separator

The hydrogen is recycled and the liquid sent to distillation


Process variables

Reactor temperature is the primary means of conversion

control..200C increase in temperature almost double the

conversion rate

Reaction Pressure: The primary effects of pressure on

conversion is in its effects on the partial pressure of

hydrogen which increases conversion…the effects of

partial pressure of ammonia is to decrease conversion but

this effect is smaller than the increase of partial pressure of

hydrogen


Space velocity: The volumetric space velocity is the ratio of liquid flowrate in barrels per hour on the catalyst volume in barrels.

The catalyst volume is constant, therefore , space velocity varies directly with feed rate. As feed rate increases, the contact time with catalyst decreases and therefore the conversion decreases


Nitrogen Content: The increase of nitrogen content will

deactivate more the catalyst and therefore conversion

decreases

Hydrogen sulfide: A small concentration of H2S acts as

catalyst to inhibit the saturation of aromatic rings which

have higher octane number than the naphtenic. However,

small amount of H2S produces very low smoke point jet fuel

( Bad burning quality jet fuel)


Hydrogen sulfide: A large amount of H2S increases

corrosion and inhibit the cracking activity of the catalyst

Heavy Polynuclear Aromatics: HPNA

HPNA are formed in small amounts from hydrocracking

reactions….these amounts can build up when the

fractionator's bottoms is recycled and causes fouling of

heat exchangers


ETHYLENE

Lightest olefinic hydrocarbon

Does not occur freely in nature

Largest building block for a variety of petrochemicals such as plastics, resins, fibers, solvents,…

Produced primarily from the thermal cracking of hydrocarbons feedstocks derived from natural gas and crude oil


PRODUCTION OF

ETHYLENE

Thermal Pyrolysis of hydrocarbons

Conventional feedstocks include ethane, propane, butane and naphta

Reaction of cracking occurs in tubular coils located in the radiant zone of furnaces

Steam is added to reduce the partial pressure of hydrocarbons in the coils

Transformation of saturated hydrocarbons to olefins is endothermic reaction and require temperature around 750 to 9000C


Reactions of thermal cracking

Rice and Herzfeld proposed the concept of free radical mechanism

Chain Initiation: Initiation of Radicals

CnH2n+2 CmH2m+1. + C(n-m)H2(n-m)+1.

Chain propagation: Reaction of Radicals with molecules

CnH2n+2 + CmH2m+1. CnH2n+1. + CmH2m+2

CnH2n+1. CmH2m + C(n-m)H2(n-m)+1.

Chain Termination: Disappearance of radicals

CnH2n+1. + CmH2m+1. CnH2n + CmH2m+2


PROCESS

First Stage: Pyrolysis or cracking of feed

Second Stage: Gasoline fractionator to remove heavier fuel components if the feed is naphta. Bottom temperature 190 to 2300C and Top temperature 95 to 1200C

Third Stage : Fuel Oil Stripper where fuel oil are stripped and sent to fuel handling facilities

Fourth Stage: Water Quench tower where the cracked gas is cooled to 400C with circulating water


PROCESS

Fifth Stage: Compression: The cracked gas leaving the quench tower is compressed to 32 to 37 bars in four or five centrifugal compressor

Sixth Stage: Acid gas removal and drying:

between the third and fourth stage of compression, CO2

and H2S are removed with dilute caustic soda

Seventh Stage: Chilling train and Demethanizer

to separate H2, ethane from C2+


PROCESS

Eighth stage: Deethanizer and Ethylene

production


High Density Polyethylene

HDPE

The Hastalen process is designed to

produce HDPE from ethylene monomer

The Process consists on 2

polymerization reactors that can be

operated in parallel ( unimodal product)

or in series ( bimodal product)

Catalyst is injected in the stirred slurry

reactor where the liquid phase is hexane

as suspending agent


HDPE

After the reaction, the polymer is

separated from the slurry mixture and

dried

The polymer is send to the extrusion

unit


PROCESS

Catalyst preparation and feeding

Polymerization

Powder drying

Extrusion and pellets handling

Hexane recycling

Butene recycling


Catalyst preparation

Production of Catalyst THT/THE/ THB is

performed batchwise from four

commercially available components in

one catalyst preparation vessel under

precisely defined conditions

Finished catalyst batches are

transferred into catalyst dilution vessels

and further diluted to the correct

concentration


POLYMERIZATION

The reactors are CSTRs. They are operated at different conditions and residence times

The reactor is fed continuously with monomers, catalyst and co catalyst, hydrogen and hexane recycled from the process

The reaction is extremely exothermic; the pressure is around 5 to 10 bars and the temperature around 75 to 850C.


The heat of reaction is removed by

cooling water


HDPE Powder Drying /

Diluent's separation

Suspensions leaving the receiver ( Figure) are

separated in a decanter centrifuge into a liquid

and a solid fraction

The solid part will feed a fluidized bed dryer

operated with nitrogen and the liquid part (

hexane) goes back to reactors

Dried HDPE powder passes through a sieve

and is pneumatically conveyed by nitrogen to

the extrusion unit


Reaction Mechanisms

The Hostalen process is based on a

Ziegler reaction mechanism with the so

called ziegler catalyst.

These catalyst are produced with TiCl4and Al(C2H5)3 according the the formula

given in Figure


POLYPROPYLENE

The polymerization of propylene to polypropylene was performed in 1954 by Giulio Natta ( 1963 Nobel prize in Chemistry)

Propylene can polymerize into three distinct structural chains ( Figure 16.1.1)

* Isotactic

* syndiotactic

* atactic


Isotactic PP occurs when all the methyl

groups are located on the same side

Syndiotactic PP occurs when the methyl

groups are located on alternating sides

of the chain

Atactic PP occurs when the methyl

groups are randomly dispersed around

the chain


The catalyst System

The catalyst system is composed of:

* Solid catalyst, generally TiCl4supported by MgCl2

* an internal or external Lewis Base

* an Aluminium Alkyl


Catalyst Function

The catalyst is composed of two main

elements: a transitional salt and an inert

support structure

The MgCl2 support has the following function:

* It creates a highly disorganized crystalline

structure the reaction sites are greater in

number and therefore higher activity

The active part of the catalyst ( TiCl4) should

be activated by an Aluminum Alkyl and Lewis

base


Catalyst Evolution ( Table 16.1.1)

The rapid & successful

commercialization of PP is due to the

continuous development of new

improved catalysts

the yield of catalyst has increased from

1 to 120 kg/ g catalyst


Polymer Chain Control

The length of the polymer chain has a significant impact on its performances and mechanical properties.

Direct measurement of the chain length is difficult For many years the intrinsic Viscosity IV was used

IV results were directly related to the polymer chain

The higher the IV the longer is the chain


Recently, The melt-flow rate (MFR) technique is used

MFR is the weight of melted polymer that can flow through a specific orifice under standard conditions

Standard Load = 2.16 kg

Standard temperature = 230 0C

Standard Time = 10 min


Molecular Weight Distribution

(MWD)

In the polymer, the chains have different length

and one way to know the length distribution is

the MWD

A fundamental measurement of MWD is gel

permeation also known as size-exclusion

chromatography

In this technique, the polymer is dissolved in a

solution and the chains elute at different times

through a porous media


MWD

We can distinct Mn and Mw

Mn is the number average molecular weight

Mw is the weight average molecular weight

i

ii

nn

MnM

iiiiw MnMnM /2


Polydispersity

Polydispersity is the ration of Mw/Mn

Polydispersity is used to describe the

MWD


PP Polymerization Processes

In the 1960’s, PP process used first

generation low-yields catalyst ( <

1000kgPP/ kg of catalyst) in mechanically

stirred reactors filled with an inert hydrocarbon

diluent

PP produced had unacceptable high residual

metals and contained 10% atactic PP which

needed separation


Second Generation catalyst

An intermediate step was reached with

a second generation catalyst increasing

yield to 6000/15000Kg PP by kg of

catalyst

But isotacticity not yet at level that allow

simplification of the process


Third Generation Catalysts

In the 1970’s, the discovery of the third

generation catalyst ( 15000 to 30000kg

PP by kg catalyst) eliminated the need

for catalyst residue removal but atacticity

was still high and the atactic recovery

step was not eliminated


The Fourth Generation

Catalyst

In the 1980’s, the fourth-generation high yield , high selectivity ( HY/HS) catalyst was discovered ( 30000kg of PP by kg of catalyst)

this eliminated the need of catalyst and atactic removal

In 1982, the Spheripol process was developped


Spheripol Process

It has the unique ability to produce

polymer spheres directly in the reactor

Spherical PP differs considerably from

the small, irregularly shaped, granular

particles produced by other technologies


Process Description

The Polymerization Unit involves the following

sections:

* Catalyst Feeding

* Polymerization:

- Prepolymerization

- Bulk Polymerization

- Gas phase Polymerization

- Finishing


The catalyst

The catalytic system has three

components:

- Solid catalyst

- Aluminium Alkyl used to activate the

catalyst

- Lewis Base used to control the

cristallinity and the homopolymer grade


Bulk polymerization

Bulk Polymerization employs jacketed tubular reactor completely filled with liquid propylene to produce homopolymer, random copolymer and terpolymer

The catalyst, liquid propylene and the hydrogen are fed continuously into the loop reactor

The Polymerization reaction is exothermic


Commercial uses of PP

Table 16.3.1


Synthetic Polymers

The synthetic polymer industry is the major

use of many petrochemical monomers such as

ethylene, propylene, styrene and vinyl chloride

Many articles previously produced from natural

material such as wood, cotton, wool, iron ,

aluminum and glass are now replaced or

partially substituted by synthetic polymers

Polymerization can now be tailored to produce

polymers stronger than steel


Thermoplastics

Polyethylene ( LDPE and HDPE)

Polypropylene

Polyvinyl Chloride (PVC)

Polystyrene

Nylon resins


POLYETHYLENE

The most extensively used thermoplastic

Because of the abundance of the monomer from the abundant raw materials ( FG, LPG, naphta)

Other factors include

* Low cost, ease processing the polymer, resistance to chemicals,

World production of PE was 100 billions pounds in 1997 and predicted 300 billions pounds in 2015

The two grades of PE include LDPE and HDPE


LDPE

Produced under High pressure in the presence of free radical initiator

Temperature of reaction: 100-2000C

Pressure of reaction: 100-135 atm

Polymer highly branched (?)

Low crystallinity (?)

By adding copolymers , we obtain copolymers with lower crystallinity, higher impact stenght


HDPE

Low pressure process

High cristallinity

high melting point ( compared to LDPE)

due to absence of branching


Properties and uses of PE

Inexpensive thermoplastic

can be modeled to almost any shape, extruded into fibers or filaments and blown or precipitated into films or foils

LDPE is flexible and transparent can be used for the production of films and sheets and for film production

HDPE can be used to produce bottles and hollow objects by blow molding ( about 64% of bottles are made by HDPE)

Injection molding is used to produce solid objects

Pipes produced from HDPE are flexible, tough and corrosion resistant


POLYPROPYLENE (PP)

Major thermoplastic polymer

The delay in PP production is attributed to its polymerization

PP produced by free radical is mainly atactic form having low cristallinity which is not suitable for thermoplastic or fiber use

The turning point in PP production is the development of a Ziegler-type catalyst developed by Natta to produce isotactic PP


Properties and Uses of PP

Good chemical and electrical resistance

Low water absorption

Light weight ( lowest thermoplastic

polymer density)

High abrasion resistance

high impact strength

no toxicity


PP can be extruded into sheets

Due to its light weight and toughness,

PP is widely used in automobile parts


PVC

widely used thermoplastic

blow modeled into bottles, used in common

items such as garden hoses, shower curtains,

irrigation pipes, paint formulation

Excellent chemical and abrasion resistance

self extinguishing due to the presence of

chlorine atom

Can be used as tablecloth, cable insulation


POLYSTYRENE (PS)

Polymerized by free radical or using coordination catalysts

Copolymers Styrene- acrylonoitrile (SAN)

have higher tensile strength than PS

A copolymer of acrylonitrile, butadiene and styrene (ABS) is an engineering plastic due to its better mechanical properties


Properties and Uses of PS

Highly amorphous if produced by free radical

polymerization

SBR ( a block copolymer with 75% Butadiene

) is produced by anionic polymerization

PS is used mostly in packaging

Molded PS is also used in automobile interior

parts, furniture and home appliances


Project by Internet

Uses of PE

Uses of PP

What is PVC ( polyvinyl Chloride)

What is PS ( Polystyrene)

Date post:	31-Jan-2016
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