PHAN TICH DAU THO VA SAN PHAM

KỸ THUẬT PHÂN TÍCH DẦU THÔ VÀ CÁC SẢN PHẨM DẦU MỎ Analytical techniques for crude oil and petroleum fractions... Tách và phân tích cơ bản dầu thô và các phân đoạn dầu mỏ III.. Xác định

KỸ THUẬT PHÂN TÍCH DẦU THÔ

VÀ CÁC SẢN PHẨM DẦU MỎ

Analytical techniques for crude oil and petroleum fractions

NỘI DUNG

I Thành phần của dầu thô và các sản

phẩm dầu mỏ

II Tách và phân tích cơ bản dầu thô và các

phân đoạn dầu mỏ

III Xác định các tính chất đặc trưng của

dầu thô và các sản phẩm dầu mỏ từ các phân tích cấu trúc

IV Xác định các tính chất đặc trưng các

phân đoạn dầu mỏ bằng kỹ thuật sắc ký

Content

I Composition of crude oil and petroleum

products

II Fractionation and Elemental analysis of

crude oils and petroleum cuts

III Characterization of crude oils and

petroleum fractions based on structural analysis

IV Characterization of Petroleum fractions

by chromatographic techniques

Chương 1: Thành phần của dầu thô

Chapter 1: Composition of crude oil and petroleum products

Principal petroleum product, their boiling range temperatures and their number of carbon atom

Composition of

Crude Oils and

petroleum products

Composition and chemical structures

Hydrocarbons Carbon - Carbon molecule

Linked by Single bond Multiple bonds

Saturated aliphatic hydrocarbons Saturated cyclic hydrocarbons Aromatic hydrocarbons

Unsaturated aliphatic hydrocarbons

cycloparaffins naphtenes

olefins alkenes

Composition and chemical structures

Non Hydrocarbon compounds

Molecules contain atoms other that carbon and hydrogen

Hetero-organic compounds C Sulfide

Composition and chemical structures

Complement for Nitrogen compounds

Neutral compounds

Basic nitrogen

Composition and chemical structures

Complement for Organometallic compounds

Composition and chemical structures

Non Hydrocarbon compounds

Compounds whose chemistry

incompletely defined

 Asphaltenes

 Comprise an accumulation of condensed polynuclear

aromatic layers linked by saturated chains

 Shiny black solids whose MW = 1000 ÷ 100,000

 Obtained in laboratory = precipitation in n-heptane

 Resins

 Generally molecules having aromatic characteristics and

contain heteroatoms (N, O, S, occasionally Ni and V)

 MW = 500 ÷ 1000

 Frequently called “polar compounds” or “N, S, O

compounds”

Compounds whose chemistry incompletely defined

 Asphaltenes

Composition and chemical

structure

Compounds whose chemistry incompletely

defined

Separation procedure for heavy fractions and current analysis methods

Composition and chemical structure

Compounds whose chemistry incompletely

defined

Separation procedure for heavy fractions and current analysis methods

Chương 2: Tách và phân tích nguyên tố dầu thô và các phân đoạn dầu mỏ

1 Phân tách dầu thô

Chapter 2: Fractionation and Elemental analysis of crude oils and petroleum cuts

1 Preparatory and analytical fractionation

1- Preparatory and analytical fractionation

Preparatory laboratory distillation

PREPARATION AND ANALYTICAL FRACTIONATIONS

ASTM D-2892 test method

Material having a boiling range from 0 ÷ 400°C

1

2

Corresponded to a laboratory technique defined for a distillation column having 15 ÷ 18 theoretical plates.

Test knows as the TBP for “True Boiling Point"

Non Preparatory laboratory distillation

characterize the feed itself

≠

1.1.1 Preparatory laboratory distillation

 ASTM D 2892

 Sample size = 0.5 ÷ 30 liters

 Purposes:

 Recovery of liquefied gas, distillation and residue

 Determination of both weight and volume yields

for the cuts

 Generation of a distillation curve giving

temperature as a function of weight or volume recovered.

 The apparatus can be used for either

atmospheric distillations or low pressure distillations as low as 2mm of mercury.

1.1.1 Preparatory laboratory distillation

 ASTM D 2892

 Results are calculated as boiling temperature as a

function of the volume recovered (Table 2.1)

 Heavy fractions

 ASTM D 1160

 Results are presented as a distillation curve showing

the boiling temperature (corrected to atmospheric pressure) as a function of the distilled volume

Apolar column

The elution of components is a function of their boiling points Correlation between retention time and boiling point is established

PREPARATION AND ANALYTICAL FRACTIONATIONS

Distillation simulated by gas chromatography - D2887

3

Very sensitive

Very sensitive Universal detector

 Simulated distillation method uses GPC in conjunction

with an apolar column where the elution of components is function of their boiling point

 Column temperature is increased at reproducible rate

(programed temperature) and the area of the chromatography is recorded as a function of elution time.

 A correlation between retention times and boiling

points is established by calibration with a known mixture of hydrocarbons, usually normal paraffins, whose boiling points are known (Fig 2.2) From this information, the distribution of boiling points of the sample mixture is obtained.

 Fig 2.3 shows a

chromatogram for a VGO simulated distillation curve

 The ordinate axis, the

retention time, is related to a temperature scale using a calibration curve.

 The chromatogram is divided

into horizontal bands corresponding the desired separations.

 The detector used here is a

FID (Flamme Ionization Detector) so that %area correspond directly to

%weight

 Advantages: rapid (< 70min),

small quantity of sample (1 µ l), easy automation

In practice, simulated distillation by GPC is used

for:

 Either as a guide to control a TBP distillation

by evaluating the recovered volumes of each fraction

 Or for a very quick estimation of the yields of

the light fractions from conversion processes

 An example of the good correlation between

TBP and simulated distillation is given in Fig 2.4, where it is shown that 71% of a Kuwait crude distils below 535oC

1- Preparatory and analytical fractionation

1.2.1 Solvent extraction

 This technique is based on the selectivity of a solvent

for different families or individual components in a mixture.

 The powerful solvent properties of dimethylsulfoxide

(DMSO) are used to dissolve selectively the polynuclear aromatics found in oil and paraffins (Fig 2.5)

 These methods can be written into standards:

 Analysis of polynuclear aromatics in petroleum oils

(IP 346)

 Analysis of aromatics in products for human

consumption, as used by the Food and Drug Administration

1.2.2 Precipitation

 This technique is used to quantify one or more

components in a mixture, extracting them from mixtures to facilitate their final analysis.

 In industry, the elimination of asphaltenes from

oil involves using propane or butane The utilization of the lighter paraffin results in the heavier paraffins precipitating along with the asphaltenes thereby diminishing their aromatic characters

 The oil removed its asphaltene fraction is known as

deasphalted oil (DAO)

 The precipitated portion is called asphalt.

1.2.3 Subtractive methods for a chemical family

chemical processes

elimination of n-paraffins from a mixture by their

or inclusion compound.

elimination of aromatics by sulfonation, the elimination of olefins by bromine addition on the double bond (bromine number), the extraction of bases or acids by contact with aqueous acidic or basic solutions, …

Urea Clathrate

having a resolving power

generally less than that

of GPC, is often employed

when the latter cannot be

used as in the case of

samples containing heat

sensitive or low vapor

pressure compounds

 The field of application for l iquid

chromatography

chromatography in the petroleum world is vast:

 Separation of diesel fuel by chemical families

 Separation of distillation residues

 Separation of polynuclear aromatics

 Separation of certain basic nitrogen derivatives

 LPC can use a supercritical fluid as an

eluent The solvent evaporates on leaving the column and allows detection by FID

Chapter 2: Fractionation and Elemental analysis of crude oils and petroleum cuts

1 Preparatory and analytical fractionation

ELEMENTAL ANALYSIS

The determination of the elemental composition of petroleum cut is of prime importance

The quality of a cut Increase with H/C ratio

Decrease in hetero elements

nitrogen sulfur metals

Some definitions

SENSIBILITY

The ratio of the change in measured value corresponding

to the concentration of the element to be analyzed

DETECTABLE LIMIT (Threshold or sensitivity)

The lowest detectable value (it is considered as equal to two or three times the standard deviation obtained for a solution in which the concentration is higher than the detectable value (close to a value of blank test solution)

ACCURARY or ERROR

Agreement between reset of a measurement and true value

ELEMENTAL ANALYSIS

The determination of the elemental composition of petroleum cut is of prime importance

ELEMENTAL ANALYSIS

SAMPLING

Complex in petroleum products

Is the sample representative of the total flow

Difficulties with sample with heavy materials Sample coming from separation

NECESSARY To agitate

Heat sample carefuly

Procedures are discribed in the standards

Phantich dau tho va san pham\D4057.pdf

ASTM D 270 ASTM D 4057

And NEM 07 - 001

If agitation and heating : impossible → withdraw samples from various level → average sample

Analysis of Carbon, Hydrogen and Nitrogen

 Based on a method of combustion drawn from

Dumas method

 1 mg sample → placed in an oven heated to

1050oC and purge by a mixture of He and O2

 The combustion products pass over an oxidizing

agent (Cr2O3 or Cr3O4) → converted to CO2, H2O and NOx → carried off by an inert gas.

 Mixture passes across copper heated to 650oC

→ reduce the NOx to N2.

 Gases are separated in a GC column equipped

with a katharometer

ELEMENTAL ANALYSIS Analysis of Carbon, Hydrogen and Nitrogen Different apparatus and methodologies of combustion

N 2 , CO 2 , H 2 O

CATHAROMETRE

(C, H, N)

He, 3% 0 2 (gaz porteur)

Régulateur

de débit

CO 2 (2), H 2 O(3) NxOy(6)

Unité de combustion

Chambre

De réduction Oxyde de cuivre

Chromatographique

tube purificateu r

chambre de combustion

chambre d'oxydation

CO 2 , H 2 O

N x O y , SO 2 /SO 3 Magnésie

Oxyde de cuivre Ponce

argentée Laine d'argent

CO 2

H 2 O

N x O y

Ascarite (amiante sodée) Contrôle de

CO / H O

Système

d'acquisition

O 2 Gaz porteur

ELEMENTAL ANALYSIS Cellule Infra-rouge Different apparatus and methodologies of combustion

Signal électronique

Signal envoyé

Moteur Courant

de Foucault

CO 2

(gaz porteur O 2 )

ELEMENTAL ANALYSIS For nitrogen compounds in petroleum cuts

ELEMENTAL ANALYSIS

For nitrogen compounds in petroleum cuts

ELEMENTAL ANALYSIS Analysis of Carbon, Hydrogen and Nitrogen

Acceptable limits of this kind of analysis

With these values

For Hydrogen the accuracy is deemed insufficient for obtaining the hydrogen balance in a refined process.

For Nitrogen the sensibility is sufficient by detection by chemiluminescence's and reduction (detection by coulometer)

Concentration method :

This method can measure concentrations on the order to 5000 ppm for value less than

100 ppm The most successful method and the most costly is neutron activation.

ELEMENTAL ANALYSIS

Oxygen analysis

Oxygen is present only in small quantities in petroleum NEUTRON ACTIVATION

• Neutron bombardment in accelerator

• 16O is converted to 16N having a half-life of seven seconds

• Accompanied by emission of β and γ rays

• Oxygen concentration as low as 10 ppm detected

ELEMENTAL ANALYSIS

Sulfur analysis

Fractionation and elemental analysis of crude oils

Knowledge of sulfur content in petroleum products is imperative

The analytical methods are numerous and depend on both :

the concentration being measured the material being analyzed

ELEMENTAL ANALYSIS sulfur analysis by X ray fluorescence

This method is widely use in the petroleum industry for studying the whole range of products and for analyzing catalysts as well

Sulfur is analyzed on the Kα emission at 5.573  This method can attain (depending on the sample) concentrations on the order of 10 ppm or, with an error on the order at 20 %

FIGURE 2-6 page 33

Concept of analysis by X-ray fluorescence

ELEMENTAL ANALYSIS

Fractionation and elemental analysis of crude oils

Analysis of metals in petroleum cuts

The petroleum industry faces the need to analyze numerous elements which are either naturally present in crude oil as is particularly the case for Nickel and Vanadium or those elements that are added to petroleum products during

refining

Three methods are used :

X-ray fluorescence Atomic absorption Argon plasma emission

ELEMENTAL ANALYSIS Analysis of metals in petroleum cuts USING X-RAYS FLUORESCENCE FOR ANALYSIS OF METALS

The metals most frequently analyzed are the

following:

Nickel (Nr), Vanadium (V), Iron (Fe), Lead (Pb) as

well as metalloids, phosphorous (P), Sulfur (S) and

Chlorine (Cl) in petroleum products

Copper (Cu), Magnesium (Mg) and Zinc (Zn) in

lubrication oil additives

The detectable limits for a dispersion apparatus are

a few µg/g and vary according to the environment

around from a few µg/g for heavy elements in light

matrices to a few mg/g for light elements

Analysis of metals in petroleum cuts USING ATOMIC ABSORPTION FOR ANALYSIS OF METALS

 The sample to be analyzed can be dissolved in organic solvent

 The sample is generally mineralize in H2SO4, evaporate and the test is conducted in an aqueous environment (matrix effect)

 The solution is nebulized, then atomized : (either in air) acetylene flame (most often) or in nitrogen protoxide acetylene flame, or in graphite furnace for analysis of trace quantities

 In both case the aerosol is subjected to temperature exceeding 2300°C

 At these T, the molecules or salts are dissociated into their elemental atomic components The atoms have the capacity to absorb energy carried by the photons provided they have a well defined frequency

Analysis of metals in petroleum cuts These techniques are mono elemental methods and require a high calibration per element and a different source for each one.

Atomic absorption is extremely sensitive It is particularly suited to the analysis of

lead in gasoline for sodium in fuels oils and for mercury in gas condensate.

* The detectable limits are given for samples such as they are introduced into the apparatus; They should be previously diluted in order to be nebulized It thereby is useful to apply a dilution coefficient, usually at least 10 The dilution depends on the sample viscosity.

**After mineralisation.

Chương 3: Xác định các tính chất đặc trưng của dầu thô và các phân đoạn dầu thô từ phân tích cấu trúc

1 Phân tích các họ hydrocarbon

2 Xác định các tính chất đặc trưng của các

phân đoạn dầu mỏ bởi sự phân bố các nguyên tử carbon

Chapter 3: Characterization of crude oils and

petroleum fractions based on structural analysis

1 Analysis by Hydrocarbon Family

a Using Mass Spectrometry for determining distribution

by chemical families

b Use of Ultra-Violet Spectrometry to obtain Distribution

Hydrocarbon Family

2 Characterization of a petroleum fraction by

Carbon Atom Distribution

a Using Infrared Spectrometry to Characterize petroleum

fraction according to the nature of the Carbon Atom

b Determining the parameters of a petroleum fraction by

nuclear magnetic resonance