Fundamentals of Refining

Refining

COLLEGE OF MANAGEMENT AND ECONOMICS STUDIES (CMES)

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MB-107

Course Code: MB-107

Course Name: Refining

© UNIVERSITY OF PETROLEUM & ENERGY STUDIES

Contents

Unit 1 Growth & Development of Refining Industry in India ................................... 1

Unit 2 Crude Oil and its Characteristics ...................................................................... 7

Unit 3 Specifications of Petroleum Products & Related Tests ................................ 23

Unit 4 Integrated Refinery & Petrochemical Plants ................................................. 53

Unit 5 Future Refining Scenario .................................................................................. 85

Unit 6 Advances in Petroleum Refining ..................................................................... 89

Unit 7 Hydrocarbon Loss Minimization ...................................................................... 93

Unit 8 Energy Conservation ......................................................................................... 95

Unit 9 Gross Refining Margin ...................................................................................... 99

Unit 10 Oil Accounting .................................................................................................. 103

Unit 11 Excise & Custom – Petroleum Products ....................................................... 107

Objective

The objective of this course is to give an insight into various facets of petroleum refining forproducing finished products of the desired specifications. Various refining processes usedin the refineries have been dealt in this module. Characteristics of crude and specificationsof various petroleum products have been explained in detail. Dealing with growth anddevelopment of petroleum refining industry in India, latest advancements in varioustechnologies for improving profitability of the refineries in the face of increasingly stringentproduct specifications for meeting environmental stipulations have also been described.

An Overview

Refining of petroleum for producing fuel and related products for automobiles, domesticconsumption and meeting the needs of the power sector, petrochemicals, fertilizers etc.and other industries, is very vital for the economic progress of the country. The refiningindustry in India has made tremendous progress since independence with its march intime with the country's economic growth and overall progress. Starting with theestablishment of the first public sector refinery at Guwahati (Assam) in 1962, it has come along way with the setting up of most modern, state of the art and highly energy efficientrefineries of the present day. India has 17 operating refineries processing both indigenousand imported crudes. The crude processing capacity of the country has increased from 6MMTPA in 1962 to 113 MMTPA as of today. Oil companies in India have met the challengesof the petroleum market product demands with the desired stringent specifications fromtime to time, by making changes/ improvements in their processes while at the same timesustaining their profitability.

The refineries are highly capital-intensive industries with a medium gestation period andproduce crucial products for meeting the country's needs including that of defence. Forsetting up a 6 MMTPA capacity refinery complex with marketing facilities, investments tothe tune of Rs 5000 crores are required. These refineries need to be run efficiently so as tomake profits, and hence need to be modernised and updated from time to time.

The module on refining covers various facets of petroleum refining. Various refiningprocesses used in the refineries have been dealt with in this module. Characteristics ofcrude oil and specifications of various petroleum products have been explained in detail.Dealing with growth and development of petroleum refining industry in India, latestadvancements in various technologies for improving profitability of the refineries in theface of increasingly stringent product specifications for meeting environmental stipulationshave also been described.

Unit 1

Growth and Development ofRefining Industry in India

With the growth of industry and improvement in the livingstandard of people, demand for petroleum products isincreasing rapidly. Consequently, there is a thrust onincreasing their supply by enhancing refining capacity.

First refinery in India started soon after oil productionstarted in Digboi, Assam. Thereafter addition of refineriesand capacity augmentation continued unabated. Now we arehaving seventeen operating refineries with a total capacityof 113 MMTPA.

The Important Milestones

1866 - Oil discovery at Nahorpung, Assam.

1889 - Oil Production started at Digboi, Assam.

1893 - First Refinery started at Margharita, Assam.

1899 - Assam Oil Company was formed.

1901 - Digboi Refinery was commissionedsupplanting the earlier refinery at Margarita.

1947- 1957 Setting up of three coastal refineries by MultiNational Oil Companies (MNCs)

1

Objectives

After studying the unit, the learner will be able to:

y Get an overview of the growth of the Indian Refining Industry afterindependence.

y Know about special features of Indian Refining Industry.

y Get a good idea of various challenges facing the industry in thepresent time/in future and strategies for meeting the same.

Notes

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u 2 at Mumbai (Esso & Burmah Shell)

u 1 at Vizag (Caltex)

The MNCs were already marketing petroleumproducts in India by then.

1954 - Indian Oil exploration with the help of RussianGeologists.

1956 - Formation of Oil and Natural Gas Commissionfor exploration and production of crude oil andgas.

1958 - Discovery of Cambay oil field.

1958 - Indian Refineries Ltd (IRL) was formed in thepublic sector to install refineries and pipelinesin India.

- Oil India Ltd (OIL) was formed as a jointventure company between Government ofIndia and Burmah Oil Co.

1959 - Indian Oil Company formed for marketing ofpetroleum products.

1962 - The first refinery in the public sectorcommissioned at Guwahati (0.75 MMTPA)under IRL.

1963 - Indian Oil Blending Ltd – A JV between IndianOil Co. and Mobil Petroleum Co. Inc. wasformed for manufacture of lube oils andgreases.

1964 - IRL was dissolved and merged with Indian OilCo. Ltd, to form Indian Oil Corporation Ltd(IOCL).

1974 - IOBL became part of IOCL.

1981 - Assets of erstwhile Assam Oil Co. were takenover and vested in IOC as Assam Oil Division(AOD).

1998 - Panipat Refinery of IOC commissioned.

Activity 1 A

Reader may like to draw aGeneological Chart of the currentrefineries operative in India.Please classify by company,technology and year ofestablishment and expandedcapacity wherever applicable bythe end of 10th 5 year plan i.e.2006 – 07.

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1999 - Reliance Petroleum Refinery at Jamnagar,commissioned.

2000 - Numaligarh refinery commissioned.

In the five decades since independence, 16 refineries havebeen added in the public/private/ joint sectors (includingthree in the private sector by MNCs, which subsequentlybecame PSU’s).

Future Outlook* (as per 2025 vision document)Total Refining Capacity

MMTPA

2002 – 03 135Barauni ExpansionHaldia ExpansionHPCL, Mumbai ExpansionCPCL, NagapatinamRPL ExpansionEssar Oil

2003 – 04 170Koyali ExpansionPanipat ExpansionBPCL ExpansionCPCL ExpansionBRPL ExpansionParadipEssar Oil ExpansionNagarjuna Oil

2004 – 05 176Kochi Refinery Expansion

2005 – 06 214Essar Oil ExpansionRPL ExpansionBhatinda

2006 – 07 221BRPL Expansion

Bina

Activity 1 B

What are various options forincreasing the Refining Capacityin the country?

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* The anticipated growth in petroleum products may not take place

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Refining Capacity in India as in the year 2002

Indian Refining Industry � Emerging Scenario

u Shifting product demand

u Stringent product specifications

u Stringent environmental regulations

u Feedstock quality deterioration

u Globalisation

u Deregulation of oil and gas sector

Indian Refining Industry � Special Features

u Larger requirement of middle distillates (diesel,kerosene)

u Prevalence of old as well as modern technologies

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No. Refineries MMTPA Year of Commissioning

1. Indian Oil Corporation Limited, Digboi 0.65 1901

2. Indian Oil Corporation Limited, Guwahati 1.00 1962

3. Indian Oil Corporation Limited, Barauni 3.30 (6.0) 1964

4. Indian Oil Corporation Limited, Koyali 13.5 (18) 1965

5. Indian Oil Corporation Limited, Haldia 3.75 (7.5) 1974

6. Indian Oil Corporation Limited, Mathura 7.50 1982

7. Hindustan Petroleum Corporation Limited, Vizag 7.50 1975

8. Hindustan Petroleum Corporation Limited, Mumbai 5.50 1954

9. Bharat Petroleum Corporation Limited, Mumbai 8.90 1955

10. Cochin Refineries Limited, Cochin 7.50 (10.5) 1966

11. Chennai Petroleum Corporation Limited, Chennia 6.50 (9.5) 1969

12. Bongaigaon Refineries Limited, Bongaigaon 2.35 1972

13. Madras Refineries Limited (CBR), Nagapatinam 0.50 1994

14. Mangalore Refineries & Petrochemicals Ltd., Mangalore 6.00 (9.0) 1995

15. Indian Oil Corporation Limited Panipat 6.00 1998

16. Reliance Petroleum Limited, Jamnagar 27.00 1999

17. Numaligarh Refineries Ltd., Numaligarh 3.00 2000

Total Capacity 112.45

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u A few refineries with size far lower than worldstandards.

Strategies for Indian Refineries

u Residue upgradation technologies for heavy crudes

u Technologies for producing lighter fuels

u Process technologies to improve quality with respect to:

– performance parameters

– eco-friendly products

u Value addition to refinery streams

u Increased emphasis on Process Control/ Automation

u Evolutionary/innovative technological changes expectedrather than revolutionary ones

u Refineries to be integrated ,compact and flexible withrespect to crude/ product mix.

Future Technological Challenges

u Meeting higher demand of petroleum products (viz.distillates)

u Meeting higher standards of product qualities

u More emphasis on environment

u Value addition to refineries

u Technologies to improve margins

u Zero emission refinery

Capacity Increase (To Meet Demand ofPetroleum Products )

u Low cost revamps/ addition of units

u Run length improvement of units

u Infrastructure development for crude receipt/storage/distribution

u Installation of matching secondary processing plants.

Activity 1 C

i. Describe special features ofDownstream Industry.

ii. Challenges faced andstrategies to meet the same.

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Value Addition

u Production of value added products from refinerystreams

u Propylene, butene – 1, butene – 2, N – Paraffin, Lab,Benzene, Toluene, Hexane, P – Xylene etc.

u Generation of power from heavy ends

Distillation Range Improvement

u New residue conversion technologies like FCC,Hydrocracker, RDS-RFCC

u Advanced controls and optimisation

u Advanced catalysts

u Continuous simulation of plants/ product mix throughcomputer models

u Prudent selection of technologies and properintegration of secondary units/ plants.

Review Questions

1. Please identify technological challenges that refinerieswill face in future.

Notes

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Unit 2

Crude Oil and ItsCharacteristics

Crude Oil Characteristics and its Significance(General Information)

Crude oils are formed by the action of geological processeson the remains of ancient marine life.

It is a complex mixture of hydrocarbons and over 16,000compounds have been identified in one sample.

Composition varies widely:

– By geographical location

– Mix of individual wells

– Variance of wells with time

Chemistry of Petroleum

Crude oil contains almost all known hydrocarbons and non-hydrocarbons. As it is drawn from the earth, it also containsimpurities like water, mud and salts which get associatedduring its production and transportation.

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Objectives


y Understand the chemistry of petroleum, different types of crudesand their characteristics.

y Develop an insight into the significance of various characteristicsof crudes and method of determination of the same.

y Get an idea of various crudes used in Indian Refineries.

y Appreciate the difference between Indian crudes and typical middleeast crudes.

Activity 2 A

How is the crude oil formed?

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Crude oil, the basic raw material of refining industry, is amixture of eight different hydrocarbon families:

i. Paraffins

ii. Cyclopentanes

iii. Cyclohexanes

iv. Cycloheptanes

v. Di-cyclo-paraffins

vi. Benzenes

vii. Aromatic cycloparaffins

viii. Dinuclear and polynuclear

Aromatics are present in smaller amounts in compoundscontaining metallic constituents such as Vanadium, Nickel,Iron, Copper, Magnesium, Calcium, Zinc, Titanium etc.Besides impurities such as Sulphur, Nitrogen and Oxygencompounds mostly present in high boiling point fractions arealso present in crude oil. Based on boiling point, the fractionsare separated and given secondary treatment to utilise it asfinished products. Based on proportion of types ofhydrocarbon, it can be divided into Paraffin, Napthenic andAromatic categories. The purely hydrocarbon content maybe as high as 97% and as low as 50% for heavy crude oils. Thenon-hydrocarbon portion retains hydrocarbon characteristicsas the molecules contain one or two atoms of elements otherthan carbon and hydrogen. The carbon content is between 83to 87% and hydrogen content between 11 to 14%. The ratioof carbon to hydrogen increases from the low to highmolecular weight fraction due to increase in polynucleararomatic and multi ring cycloparaffins in these higher boilingfractions. Atmospheric distillation is adopted for separatingthe compounds present into various fractions upto 366ºC:-

i. Overhead gases containing mainly methane, ethane,propane and butane.

ii. C5–90º C light naptha

iii. 90ºC–140ºC heavy naptha

iv. 140ºC–204ºC Mineral Turpentine Oil (MTO)

Activity 2 B

What are the type of hydrocarbonspresent in the crude?

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v. 140ºC–240ºC Aviatin Turbine Fuel (ATF)

vi. 140ºC–270º Kerosene

vii. 270ºC–340ºC Gas oil

viii. 340ºC–366ºC Jute Batching Oil (JBO)

366ºC plus fraction i.e. Reduced Crude Oil (RCO) is subjectedto vacuum distillation for obtaining vacuum gas oils, rawLube Distillate and short residue. Various fractions obtainedfrom atmospheric and vacuum distillation are given furthertreatment to meet required specifications for use.

Crude Assay

Crude Assay is the determination of properties of variousfractions of crude oil. This is done to assess the utilityof the crude for processing for production of variousproducts and their yields. Crude Assay Data are utilised forthe following:

u Crude oil selection

u Crude oil grading

u Crude valorization

u Crude swapping

u Crude imports

u Creation of new infrastructure at the existing refineries

u Grassroot refineries

u Production planning management

u Inventory problems

u Demand/supply gaps

Types of Evaluations

Preliminary Assay

u Crude characteristics – Consistency of crude supply.

Activity 2 C

i. How do you classify crudesbased on proportion of type ofhydrocarbon present in them?

ii. What is Crude Assay? How arethese Assays utilized?

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Short Evaluation

u Crude characteristics u Absorption of newcrude in fuel refinery

u TBP assay u To study the change inquality of crude over aperiod of time

u Yield data and key u Detailed characteri-characteristics of straight sation of crude oilrun cuts in fuel range and including all microlong residue constituents.

Detailed Evaluation

u Design data for grass u TBP assay inroot refinery atmospheric and

vacuum range

u Product optimisation u Selection and design ofsecondary conversionunits.

u Yield and characterist-ics of sets of distillatesin atmospheric andvacuum range withvariation in IBP, FBPcharacterisation ofseveral long and shortresidues.

Information Required

u Base and general properties of crude oil

u Presence of impurities

u Operating and design data

– Fractionating or TBP distillation curves

– Equilibrium of flash vaporization curves

– API or specific gravity curves of each fractiondistilled.

Notes

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u Property curves of fractions vs% distilled

– Mid% curves

– Yield% curves

– ISO% curves

u Properties and yield of straight run fractions andresidues

u Detailed composition of light distillates

u Hydrocarbon Type Distribution of Middle and HeavyDistillates

Characteristics of Crude Oil

Basic Properties Impurities

Density & API Water Content

Reid Vapour Pressure (RVP) Salt Content

Light End Analysis BS & W

Pour Point Sulphur Content

Viscosity Nitrogen Content

Wax Content Inorganic and

Asphaltenes Total Acid

Carbon Residue Trace Metals

Ash Content

Distillation Characteristic (D86 or D285)

Base of Crude Oil

Crude Oil Characteristics and their Significance

Density

Density is used for:

u Weight to volume or vice versa calculations

u Checking the consistency of crude supply

u Control of refinery operations

u Used in various correlations

Notes

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u Also gives a rough indication of type of crude oil

MASS (M)Density =

VOLUME (V)

M/VSpecific GRAVITY=

M’/V (WATER)

141.5API GRAVITY= –131.5

SP.GR AT 60/60°F

Examples:

Water = 10 API

Kerosene = 45 API

Motor Gasoline = 58 API

Natural Gasoline = 75 API

Crude oils are categorised based on gravity

Light grades : Above 33 degree API

Medium grades : 23-33 degree API

Heavy grades : upto 22 degree API

CRUDE Density API TYPE TOTAL DISTILLATE UPTO 370ºC

Narimanam 0.7920 47.08 I 79.6

Ankleshwar 0.7930 46.85 I 78.2

Jotana 0.8161 41.80 P 52.0

Bombay High 0.8278 39.35 I 65.4

Heera 0.8412 36.62 I 60.6

Kalol 0.8414 36.55 P 47.0

Rumaila 0.8448 35.90 I 55.7

Ratna 0.8484 35.20 I 51.0

Rostam 0.8495 35.00 I 59.7

Jhalora 0.8496 35.16 I 42.1

Basrah 0.8527 34.40 I 52.5

Sobashan 0.8549 33.99 P 43.0

N. Gujarat 0.8553 33.85 I 44.0

Geliki 0.8675 31.50 I 54.5

Nahorkatiya 0.8688 31.30 I 60.9

Kuwait IF IR. 0.8698 31.10 I 47.0

Oman

Elmorgan 0.8727 30.55 I 48.1

Jorajan 0.8821 28.84 N 60.7

Kharsang 0.8910 27.22 N 61.7

Lakwa 0.8952 26.50 N 53.7

Jhalora 0.8986 25.87 I 31.8

Kothana 0.9000 25.64 I 28.2

Rudrasagar 0.9210 22.10 N 60.3

Sanand 0.9242 21.45 I 24.4

N- Kadi Mix 0.9340 19.91 I 27.6

Badarpur 0.9430 18.39 N 60.6

Santhol 0.9507 17.29 I 22.9

Notes

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Sulphur

Crude oils are also categorised based on sulphur.

u Sulfur is a measure of “sourness” and “sweetness” ofcrude

- Sweet grades<0.5% of Sulphur

- Sour grades >0.5% of Sulphur

Sulphur is passed on to products as much as regulations ormarket accepts. It is removed in hydrotreater by reactingwith H2 and recovered as elemental sulfur in SRU.

Reid Vapour Pressure (RVP) and Light End Analysis

RVP indicates relative Percentage of gaseous and lighterhydrocarbons in crude oil.

Component RVP, Kg/cm 2

Propane 14.1 Kg/cm2

Butane 6.6 Kg/cm2

Crude Oil 0.01-0.05

Light end analysis carried out by GLC actually gives thepercentage of hydrocarbons upto C5 and is the basis ofassessing the LPG potential of crude.

TYPICAL HYDROCARBON ANALYSIS

Components % WT on Crude

C1 ND

C2 TRACES

C3 0.1

ISO-C4 0.1

N-C4 0.3

ISO-CS 0.3

N-C5 0.5

TOTAL 1.3

Notes

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Flow Characteristics of Crude Oils

Characteristics BH Crude Basrah Crude

WAX, % WT 10.9 3.5

Pour Point,°C +30 -24

Viscosity Kinematic cst

AT 37.8 °C, 50°C 4.30, 3.32 6.18, 4.84Geological CharacteristicsYield Value Dynes/ cm2 AT

32°C 45.0 2.0

24°C 85.0 5.0

18°C 222.0 10.0

16°C 330.0 12.5

Plastic Viscosity, C.P. AT

32°C 7.9 9.6

24°C 30.7 14.7

18°C 43.7 16.0

16°C 45.0 17.3

Pour Point

u Indicates relative amount of wax present in crude oil

u Is the temperature below which pumping andtransportation problems may be encountered

u Along with viscosity, is used in pumping and designcalculations:

Wax Content

Normal paraffins above C16 are solid at somewhat ambienttemperatures. These hydrocarbons

u Affect the flow behaviour of crude

u Affect the product quality of gas oil, VGO and asphalt

u Lube manufacture is also dependent on wax content ofthe crude.

Salt Content

It is measure of contamination in crude that will causeoverhead corrosion or foul up exchangers by settling and

Notes

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sealing. It is removed in desalter by washing and settlingmainly chlorides and sulphates of Na, K, Ca, Mg.

FIGURE 2.1 POSTULATED STRUCTURE OF STABLISED EMULSION

Problems Encountered Due to Salts

u Irregular behaviour in distillation

u Equipment corrosion in the atmospheric distillationcaused by HCL liberated due to hydrolysis of chlorides

Increased Consumption of Amonia

u Salt is a major cause of blocking and fouling of heatexchangers

u Residual product contamination

u Salts may vary widely in ratio of metal ions, thoughcommon averages are – Na: 70-75%, Mg: 15-20%, Ca: 10%.

100

75

50

25

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0 100 200 300 400

••

••

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Salt Content of Crude PTO AS NACL

To

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hlo

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d A

sh

ci %

as

HC

L %

PTB as

Activity 2 D

i. How do you separate variousfractions present in crudes?

ii. What are various impurities incrudes, their bad effects andhow are these impuritiesremoved?

iii. Method of determination ofsalt content, BS&W & Viscosity.

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Particulates

Na+ COO-

Na+ COO-

Brine Droplet

Asphaltenes

Resins Waxy Agglomerates

Alkyl Benzene

Carboxylates Naphthenates

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u Mg is most prolific producer of HCL with Ca and Na indescending order

u Small quantities of HCL may substantially enhancecorrosion of sulphur compounds

Methods for Determination of Salt Content

1. IP 77/72 Extraction with water KCNS/Ag No3

titration

2. ASTM D3230 Conductivity measurement based oncalibration with Na, Ca, Mg chloridesstandard solutions in mixed alcohol.

Sediment and Water

— Sediment has no relationship with salt but both mightincrease with connate water

– Sediment Fine particles of sand clay,volcanic ash, drilling mud, rust,iron sulphide, metals and scale

– Damaging Effects Plugging Abrasion and residualproduct contamination

– Water causes irregular behaviour in distillation.

Sediment in crude oil is measured by the following methods:

BS & W ASTM D 96

Sediment by extraction ASTM D 4007

Water content DEAN & STARK

ASTM D 4006

– Sediment in crude is determined for custody transferpurposes

– Lower the sediments and water, higher the reliabilityof the unit. It is also a major pointer for corrosivematerials in crude.

Notes

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Asphaltenes, Carbon Residue and Ash Content

Asphaltenes

u Are polynuclear condensed aromatic hydrocarbonshaving high molecular weight

u These are insoluble in heptane and soluble in Benzene/Toluene

u Asphaltenes and carbon residue indicate the extent towhich heavy hydrocarbons are present in crude oil.

Ash Content

u Metallic constituents concentrate in the ash of the crudeoil

Carbon Residue

It’s a carbonacous residue formed after evaporationand pyrolysis of the sample. The residue is coke anddetermined by

– Conradson residue method ASTM D 189

– Ramsbottom carbon residue ASTM D 624

– Micro-carbon residue method ASTM D 4630

Viscosity

It is a measure of resistance to flow and is an importantparameter for effective desalting. It is also highly dependanton temperature.

High viscosity crudes need high temperatures for effectivedesalting. There is a limit for temperature in desaltersoperation.

KUOP

It is a measure of parafinity vis-à-vis aromaticity of crude.

High KUOP is desired for high conversion in FCC, aromaticmolecules cannot be cracked in FCC. They will simply takea ride through the plant.

Activity 2 E

Significance of TAN & KUOP.

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TAN

TAN is actually Total Acid Number.

It is a measure of Naphthenic Acid (NA) contents in crude.This leads to corrosion in various sections of the unit. Over1,500 known NA species are present in crude.

All napthenic acids are not corrosive. Latest researchindicates that TAN is not a complete Corrosion Index.

TAN with 2.5 may corrode at higher rate than TAN withsay 6 !

Detailed metallurgical reviews and monitoring mechanismsmust be put in place.

Selection of Crude Oil

Technology trends in petroleum refining are driven by theexternal forces of product demand, product specifications(including environmental consideration), feed stock qualityand availability. Crude oil will gradually become heavier andhigher in sulphur content. Refineries, of late, have beensincerely attempting to produce fuels to comply with stricterenvironmental regulations particularly gasoline and dieseland are in the process of reducing the sulphur levels indistillates and fuel oil. Attention is now also being paid toreduce lead and benzene levels in gasoline. Various gasolineand diesel specifications applicable worldwide are given inthe later part of this chapter.

Crude processed in India are:

1. Indigenous crude oil sources

a. Bombay high and satellite fields

b. North Gujarat and Ankaleshwar crude

c. Assam crudes

d. KG Basin-Rava crude

e. Cauvery Basin crude

All the above crudes are low sulphur =<0.5% wt, lowmetal content, poor potential to yield LOBS andbitumen, and some are waxy in character.

Activity 2 F

What are various crudesprocessed in Indian Refineries?Where are Indigenous crudefound? What is the sulphur contentof Indian crudes?

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2. Imported crudes are sourced mostly from:

a. Gulf Region

b. Nigeria

c. Malaysia

d. Australia

The above crudes are specially selected for production ofBitumen/LOBS/ATF, beside fuel products.

These crudes are having varying range of sulphur from lowof high.

Comparison of Crudes

Comparison of Indian crudes and typical Middle-east crudemix for yield and key properties of straight run cuts:-

1. Gases upto 20ºC 4. GAS OIL 250–370ºC

2. Naphtha I.B.P.- 140ºc 5. Vacuum GAS OIL 370–530ºC,

3. KEROSENE 140-250ºC 6. Short Residue 530º, C+.

Activity 2 G

What straight run fractions areobtained in AtmosphericDistillation? And in VacuumDistillation?

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AROM. 16% Vol

NAPH. 52% VOLCOTANE NO.

73.7

SMOKE POINT 14mm Arom. 36% VOL. E.P.T.<�60ºC

DIESEL INDEX 33 POUR POINT �9ºC

KUOP II-61 KIN. VISC. AT 96.9ºC 7 0St

ºAPI 3.8

1 2 3 4 5 6

1-2 15.0 17.6 27.1 27.2 N.9

SMOKE PT. 23 mm AROM. 1:1 % VOL F.P.T.-54ºC

AROW 5.8% VOL. NAPH 40.6% V.O.N.O.

DIESEL INDEX 57 POUR POINT +3

KUOP 12.10 KIN VISC. AT 100º C 8.120 SI

ºAPI 13.58 POUR POINT +48 KIN. VISC. AT 100ºC 150(27 0SI CCR 14.77% Wt.

0.4 4.4 10-1 19.2 31.2 34.7

AROM: 6.6% VOL OCTANE No. 67.5

SMOKE POINT 27mm AROM. 15% VOL. F.P.T.�48ºC

DIESEL INDEX 67 POUR +POINT +6ºC

KUOP 12-70 KIN. VISC. AT 100ºC 405 0St

3.8 24.9 22.3 23.9 18.8 6.3

API 16.5 CCR 9.92% WI. POUR POINT + 68ºC

ASSAM CRUDE MIX ºAPI 29.85 SULPHUR 0.24% Wr. POUR POINT +30ºC WAX CONTENT 10.8% Wt. KUOP 11.30

NORTH GUJARAT CRUDE MIX ºAPI 26.83 SULPHUR 0.17%Wt.POUR POINT+21 WAX CONTENT 6.8% Wt KUOP 12.0

GANDHAR+ANKLE-SWAR (60. 40 VOLT CRUDE MIX ºAPI 46.9 SULPHUR 0.041 % Wt. POUR POINT+27ºC WAX CONTENT 8.9% Wt.

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Notes

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Selection of Crude(s) for a Refinery

Based on product demand, type of products, processingschemes of refineries, metallurgy of existing plant andequipment, crudes are selected after evaluating detailedcrude Assay Data. Mostly, a mixture of crudes is selectedfor a refinery to optimise the cost and meeting productsquality specifications.

Review Questions

1. Describe different characteristics of crudes dealt within this unit, their significance and typical values/ unitsof measurement.

2. Draw a comparison of indigenous crudes with TypicalMiddle East Crude(s) vis-à-vis important specificationsof Petroleum Products.

ARON 4% VOL. OCTANE NO.61.9

SMOKE POINT 27mm Arom. 16% Vol,. F. PT�57ºC

DIESEL INDEX 58 POUR POINT �12ºC

KUOP 12.31 KIN VISC. AT 100ºC 4.83 0St

2.7 30.4 24.7 21.8 15.7 4.7

AROM 7.3% VOL OCTANE No. 53.8

SMOKE POINT 26mm AROM. 18.6% VOL. F.P.T.�56ºC

DIESEL INDEX 58 POUR +POINT �9ºC

KUOP 11-94 KIN. VISC. AT 100ºC 5.98 0St

2.1 10.7 16.1 18.1 22.5 30.5

API 7.43 CCR 19.85% Wt. POUR POINT + 54ºC KIN. VISC. AT 100ºC 903.650St

NARIMANAM CRUDE ºAPI 47.08 SULPHUR 0.085% Wt. POUR POINT 0 WAX CONTENT 2.8% Wt. KUOP 11.98

Kuwait+Lt. IRANIAN FOMAN (56: 36: 6 VOL. ) ºAPI 31.1 SULPHUR 2.28% Wt. POUR POIN T(�30ºC WAX CONTENT 1.1% Wt. KUOP II.98

API 16.35, CCR 10.4 % Wt POUR POINT+ 60ºC

ARON 21.3% VOL. NAPH. 25% VOL OCTANE NO. 69-6

SMOKE POINT 17mm AROM. 26.9% VOL. F. PT. -49ºC

DIESEL INDEX 56 POUR POINT +3ºC

KUOP 12.37 KIN VISC. AT 98.9ºC 5.36 0St

1.9 18.6 20.9 24.0 28.4 6.2

BOMBAY HIGH ºAPI 39.35 SULPHER 0.17% Wt. POUR POINT+ 30ºC WAX CONTENT 10.6% Wt. KUOP 11.70

ºAPI 9.51 CCR 19.2% Wt. POUR POINT +72ºC



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Notes

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3. From which Indian crudes, can you produce

a. ATF

b. Bitumen

c. Lubes

d. Micro-crystalline wax

e. Good Quality Calcined Petroleum Coke

Unit 3

Specifications of PetroleumProducts and Related Tests

Specifications

What are Specifications?

Any material which is intended for use in a particularapplication should have certain characteristics so that it issuitable for use in that application. These characteristics arequantified to make them absolute and also to remove anyambiguity in the interpretation. These quantifiedcharacteristics are called “specifications”.

Some important tests conducted on petroleum productsand included in specifications:

Flash Point RON Color

Pour Point MON BMCI

Distillation AKI Bromine Number

Copper Corrosion Cetane Number Benzene Content

Silver Corrosion Cetane Index Density

Sulphur Smoke Point Sediment

Viscosity Aniline Point Water

Potential Gum Carbon Residue Weathering Test

Existent Gum Vapour Pressure

23

Objectives


y Understand the specifications of various petroleum products, their

significance and their determination/tests.

y Appreciate crucial specification of HSD & MS from Environmental

Pollution Standpoint & Strategies for meeting stringent norms for

future Euro III/IV, Bharat III/IV.

Notes

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Significance of Tests

Flash Point

It is the minimum temperature at which the sample givessufficient vapour which forms an explosive mixture with airgiving a flash when a flame is applied to it under conditionsof the test method.

Flash point is associated with safety during storage andapplication in some respects. When a product like keroseneis stored either at home or at a commercial location, it formsvapour above it depending upon the ambient temperature.If the vapour so formed is sufficient to form an explosivemixture with air, there would be explosions when a smallnaked flame is exposed to it. Each country has it ownlegislation with respect to flash point depending upon theclimatic conditions of the country.

Pour Point

When heavy petroleum oils containing wax are allowedto settle (like in storage tanks), wax separates out fromthem making the oil immobile. If the oil does not move,it cannot be pumped. The temperature at which theoil becomes immobile (does not move) is termed aspour point when tested under the conditions of the testmethods.

Distillation

The volatility of an oil is indicated by its distillationcharacteristics. Unlike pure compounds, petroleum oils aremixtures of several hydrocarbons and so will have a boilingrange instead of boiling point. The oil should have suitableboiling range (volatility) so that it can be used in a particularapplication. For example, Motor Gasoline which is used inspark ignition internal combustion engines, has the followingspecifications for distillation:

Recovery upto 70o C 10 to 45% Min

Recovery upto 100o C 40 to 70% Min

Recovery upto 180o C 90% v Min

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Since the application is in a spark ignition engine, thefuel should easily vaporise to a sufficient degree so thatwhen a spark is applied it can ignite. The specification forrecovery at 70o C is laid to meet this requirement. Themaximum limit of 45% is laid to prevent some otherundesirable effects such as vapour lock. This quality is called“easy start”.

The specification for recovery at 100oC is set to give powerto engine and take load.

The specification for recovery at 180oC and final boiling pointare set to prevent crank case oil dilution and unburnthydrocarbon in tail gases (air pollution).

Copper Corrosion

The fuel product comes on contact with metal parts such astransfer pipe from storage tank, storage tank itself, theburner in a kerosene stove, stove body itself, storage andtransportation equipment like pumps, storage vessels etc.If the product is corrosive, it will corrode these parts andreduces their life. Copper corrosion test indicates whetherthe product is corrosive to copper containing alloys or not.This test is applicable to all fuels.

Silver Corrosion

This test is done for Aviation Turbine Fuel (ATF)–Jet A1 Type

Some aircrafts of civil aviation and defence use a silver liningin the fuel transfer lines. In order to protect this lining, thefuel should not be corrosive to silver. Hence this test is donefor ATF. This is a requirement for Indian region only. Westerncountries and USA do not use this test any more.

Sulphur

Sulphur, besides being corrosive to the fuel systems, is apollutant to the air and affects life. Global efforts are beingmade to minimise the sulphur content in motor gasoline, highspeed diesel and fuel oils.

Notes

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Viscosity

Viscosity is the resistance to flow. The unit of absolute ordynamic viscosity is Poise and that of kinematic viscosity isStoke. Viscosity is an important property for lube oilsbecause it gives the lubricating property to the oil. This isrequired to prevent wear and tear in the moving parts of amachine on account of metal to metal contact. For fuel oils,it gives flow properties which are needed for pump selectionfor transporting.

Viscosity is measured in several ways. The most commonare Kinematic Viscosity measured in centi-stokes and SayboltUniversal Viscosity measured in seconds.

Potential Gum

This test is applicable to motor gasoline which may containunsaturated hydrocarbons (olefins). Olefins are oxidised byatmospheric oxygen to a gummy material which sticks tothe carburetor jet of the vehicle or inlet valve leading to valvesticking which in turn results in the malfunction of theengine. This type of gum is characterised by Potential Gumtest. It does not show the exact amount of gum that wouldform on storage but gives a directional indication. The unitof measurement is mg per liter.

Existent Gum

This test is applicable to motor gasoline.

If motor gasoline contains any soluble solid residue, theresidue gets deposited in the carburetor and other partsafter the gasoline is vaporised. Such deposit may clog thejet and prevent fuel flow due to which the engine stops. Thatis why this test is done on MS. The specification is 40 mg perlitre max.

One point should be noted. Some solid material is added toMS deliberately for some purposes. Example: Dye to identifythe MS from others. These type of residues are excludedfrom the specification.

Notes

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Octane Number

It is defined as the per cent volume of iso octane in a mixtureof iso octane and normal heptane that gives the sameknocking as that of the fuel when tested under definedconditions.

Iso octane is assigned a value of 100 and normal heptane 0octane number.

Normal paraffins have the lowest octane number. Next comesnapthenes followed by iso paraffins, olefins and aromaticsfor the same carbon number. However, this is only a generalrule and may differ in the case of iso paraffins. Some of themhave lower octane numbers than corresponding napthenesand some other higher octane number depending upon thebranching of the iso paraffin. Similarly Octane numbers ofolefins may also differ slightly as given below:

l n-Hexane 24.8

l Cyclohexane 83

l 2,2 Dimethy 1 Butane 91.8

l 2-Methyl Pentane 73.4

l Hexene-2 90

l Benzene >100

l N-Heptane 0

l Methyl Cyclohexane 75

l 2,3 Dimethyl Pentane 88

l 2 Methyl Hexene-1 92

l Toluene 107

Octane numbers are not truly additive. When used singly,the hydrocarbons behave in some way and when used in amixture, they behave in another way. For example, Toluenehas a RON 107 when it is a single component system. Butwhen it is mixed with other hydrocarbons, it behaves as ifits octane number is > 120.

Some schools of thought say that in multi-componentsystems, like naptha, octane number is additive on weightpercent basis. Some others believe that it is additive on mol.

Notes

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per cent basis. In effect, there are always some exceptionsand some deviations.

Research Octane Number and Motor Octane Number.

These are determined under different conditions of the test.

Test Condition RON MON

Engine speed 600 RPM 900 RPM

Spark advance 13 o Variable

Mixture Temp - - 300 o F

In Take Air Temp 125o F 100 o F

AKI (Anti Knock Index)

It is defined as the average of RON and MON.

AKI = (RON + MON)/2

Anti Knock Index is regarded as more critical for engineperformance than RON alone.

Cetane Number

This test is applicable to diesel fuels which use ignition bycompression.

Cetane number is defined as the per cent volume of n-cetanein a mixture of n-Cetane and alpha methyl naphthalene thatwould give the same knocking as that of the fuel under test.

n-Cetane is assigned a value of 100 and alpha methylnaphthalene a value of 0.

Alpha methyl naphthalene has some storage stabilityproblem. It turns red when exposed to air. So, although it isa primary fuel, a secondary fuel for routine use is also statedin the test method. This is hepta Methyl Nonane (HMN).Another consideration for using HMN is its easieravailability.

This test has reverse characteristics of octane number.

Here, normal paraffins have highest cetane number followedby naphthenes, iso paraffins, olefins and aromatics in general

Notes

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but the order may vary depending upon the chain length ofiso paraffins.

Cetane Index

It is an alternative to cetane number. It is nearly equal tocetane number but not an actually determined value requiredcetane engine. Cetane index is not applicable to fuelscontaining cetane improves.

Smoke Point

Smoke point is defined as the maximum length of the flamewhich does not give smoke when tested under prescribedconditions using the prescribed apparatus.

Smoke point shows the hydrocarbon nature of the fuel.Paraffins have high smoke points followed by naphthenesand then by aromatics.

The test is applicable primarily to kerosene. The mainpurpose of kerosene is for use in lantern. If the kerosenegives smoke when it burns, it gives less light. As the flamesize increases the light given out would also be more. But ifthe kerosene starts giving smoke, the height of the flamehas no meaning. So the higher the flame without smoke, thebetter.

Smoke point is related to hydrogen content of the fuel. Thehigher the hydrogen content, the higher will be the smokepoint. Paraffins contain highest hydrogen content for thesame carbon number. So the smoke point of paraffins ishighest.

The specification of smoke point for kerosene in our countryis 18 mm minimum.

Aniline Point

Aniline point is the minimum temperature at which equalvolumes of sample and aniline are miscible.

Aniline point gives the hydrocarbon nature of the oil.Aromatic hydrocarbons have lower aniline points andparaffinic hydrocarbons have higher aniline points.Naphthenic hydrocarbons have intermediate aniline points.

Notes

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Aniline point in combination with density /specific gravity/API gravity gives a quick idea of some important propertieslike Diesel Index, Aniline-Gravity Product which areimportant properties for diesel and ATF. Aniline gravityproduct is an alternative to calorific value.

Carbon Residue

Every oil, when it burns, forms a carbon deposit which isvery difficult to burn. This carbon deposits on burner tipschocking the orifices due to which the flow of oil stops andburner tip needs to be cleaned. If this carbon deposit is more,the burner tips have to be cleaned more frequently.

Carbon residue test gives an indication of the amountof carbon that would form when the oil is pyrolysed andburned.

There are two methods to determine carbon residue:

1. Ramsbottom Carbon Residue (RCR)

2. Conradson Carbon Residue (CCR)

Vapor Pressure

This is an indirect method of estimating most extreme lowtemperatures under which initial vaporisation can beexpected to take place. It can be considered as a semiquantitative measure of the amount of most volatile materialpresent in the product. It can also be used as a means ofpredicting the maximum pressures which may beexperienced at fuel tank temperatures.

Colour

Two types of tests are applicable to petroleum products1) Saybolt colour and 2) ASTM Color. The former isapplicable to white oils like kerosene, naphtha, MTO etc andthe other is applicable to diesel, vacuum distillates etc. Thecolour gives an indication of the degree of refining orcontamination with foreign bodies.

Notes

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BMCI (Bureau of Mines Correlation Index)

BMCI is an indication of predominant nature ofHydrocarbons in a product.

All normal paraffins have BMCI zero or less than zero.

A high BMCI indicates predominantly Aromatic nature.

A low BMCI indicates predominantly paraffinic nature.

Intermediate BMCI indicates mixtures of both and alsonaphthenic nature.

BMCI more than 100 indicates presence of condensed rings.

BMCI of some hydrocarbons

Hydrocarbon BMCI

N Paraffins 0 or < 0

Iso Paraffins < 15

Cyclohexane 50

Benzene 99

BMCI is a calculated value form density and 50% boilingpoint. It is defined as,

BMCI – (48640 / K) + (473.7 * G) – 456.8

Where,

K = 50% Boiling Point in o K

G = Specific Gravity @ 20 0 / 4o C

There are graphical correlations between BMCI andViscosity and Density also which are nearly equal to thecalculated value.

Bromine Number

Bromine number is defined as the grams of bromine thatreact with 100 grams of the sample.

Bromine number gives the olefinity of the sample.

Notes

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Olefins react with bromine giving additional products. Eachdouble bond absorbs two atoms of bromine.

Example:

CH3CH2CH2CH2CH = CH2+Br2 CH3CH2CH2CH2CHBRCH2Br

Benzene Content

This test is applicable to motor gasoline.

Benzene is carcinogenic (causes cancer). Its limit in MS isrecognised by all countries. The specification for benzene inIndia is 5%v for general supplies and 1% v max for suppliesto NCR.

Density

Petroleum products are liquids. They are sold on avolume basis but the custody transfers are effected onweight basis. Density is required for mass balance calculationand is also useful for several correlations which indicate thehydrocarbon nature and other properties.

Some of such correlations are, BMCI, Kuop, VGC.

Weathering Test

This test is applicable to LPG. It indicates the amount ofnon vaporisable matter in LPG.

Specifications of Petroleum Products

LPG (IS 4796)

Test Unit Specification

Density kg / M3 Report

Volatility (95% Ev Temp) o C +2 Max

Vapor Pressure @ 38 o C kg / cm2 7 Max

Copper Corrosion @ 38 o C 1 Max

Sulphur %w 0.05 Max

Odor - - Identifiable

Notes

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Motor Gasoline (IS 2796 - 2000)

PC Naphtha

Test Unit Method Requirement

Appearance Visual Clear and Bright

Color Visual Colourless

Density @ 15 C kg/M3 P:16 To Report

Distillation IBP C P:18 28 min

FBP C 160

Total Paraffins % w ASTM D 5443 74 min

Normal Paraffins % w ASTMD 5443 36 min

Iso/Nor Paraffin Ratio 1.05 max

n C6 % w To Report

n C 7 % w To Report


Color - - Visual Orange

Density @ 15 o C kg / M3 P:16 710 � 770

Distillation

Recover @ 70 o C % v P : 18 10 � 45

Recovery @ 100 o C % v 40 � 70

Recovery @ 180o C % v 90 min

Final Boiling Point o C 215 max

Research Octane Number P:27 88 min

Anti Knock Index P:26 & P:27 84 min

Existent Gum gm/M3 P:29 40 max

(Solvent washed)

Potential Gum gm/M3 p:147 50 max

Sulphur % w P:34 0.1 max

Lead as Pb gm/1 ASTM D 5059 0.013

Reid Vapor Pressure KPa P:39 35-60

VLI Summer Winter - - - 750 max

950 max

Benzene %v ASTMD 3606 5 max

1max for NCR

Cu Corrosion P:15 1

@ 50 o C for 3 Hrs

Water Tolerance

Summer 10

Winter 0

Oxygenates % v ASTM D 4815-89 15 max

NB: 1) MFA containing Phosphorus compounds should not be used

2) Potential Gum before doping MFA

Contd...

Activity 3 A

What are different PetroleumProducts?

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Aromatics % w 10 max

Olefins % w P:23 1 max

Total Sulphur ppm w P:34 B 100 – 250

Mercaptan Sulphur ppm w P:109 150 max

Reid Vapor Pressure Kpa P:39 To Report

@ 38ºC

Chlorides ppm w ASTMD 4929 5 max

Lead ppb w P:82 100 max

Arsenic and Mercury ICP To Report

Superior Kerosene (IS 1459 - 1974)


Acidity (Inorganic) mgKOH/gm P:2 Nil

Burning Quality

Char value mg/kg Oil P:5 20 max

Bloom on chimney not darker than grey

Color (Saybolt) Undyed Units P:14 +10

Dyed Blue

Copper Corrosion

@ 50 o C for 3 Hrs P:15 Not worse than 1

Density @ 15 o C kg/M3 P:16 To Report

Distillation

Recovery @ 200 o C % v P:18 20 min

Final Boiling Point o C 300 max

Flash Point Abel o C P:20 35 min

Smoke Point mm P:31 18 min

Total Sulphur % w P:34 0.25 max

Aviation Turbine Fuel (IS 1571 - 1992)


Appearance - - Visual Bright, Free from solidmatter and visuallyundissolved water.

Acidity Total mg KOH/gm P:113 0.015 max

Aromatics % v P:23 25 max

Olefins % v P:23 5.0 max

Total sulphur % w P:34B 0.30 max

Mercaptan sulphur % w P:109 0.003

Contd...

Activity 3 B

What are the key specifications ofMotor Spir it, LPG, HSD,Petrochemical Naphtha, ATF?How do these affect performance?

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Distillation

10 % v Recovered at degree C P:18 205 max

50 % v Recorded at degree C P:18 Report

90 % Recovered at degree C P:18 Report

Final Boiling Point degree C P:18 300 max

Flash Point degree C P:20B 38 min

Density @ 15 C kg/M3 P:16 0.775 to 0.840

Freezing Point degree C P:11 Minus 47 max

Kinematic Viscosity

@ Minus 20 C cST P:25 8.0 max

Aniline Gravity Product - - - P:3 4800

Smoke point mm ISO 3014 25 min

Naphthalenes % v ISO 3014 3.0 max

Copper Corrosion

% 100 degree C for 2 Hrs - - - P:15 1 max

Silver Corrosion @ 50

degree C for 4 Hours - - - IP 227 1 max

Thermal Stability

Pressure Differential mm P:97 25 max

Tube Rating Visual Visual 3 max No PeacockOr abnormal colordeposits

Existent Gum mg/100 ml P:29 7 max

MSEP - - - P:142 85 min

Electrical Conductivity ps/M IP 274 50 to 450

Lubricity mm ASTMD 5001 Report

High Speed Diesel (IS 1460 � 2000)

Test Uni t Method Requirement

Acidity Inorganic mg KOH/Gm P:2 Nil

Acidity Total mg KOH / Gm P:2 0.2 max

Aah % w P:4 0.01

RCR % w P:8 0.3 (on 10 % residue)

Cetane Number OR - - - P:9 48 min

Cetane Index - - - ASTMD 4737 46 min

Pour Point - - - P:10 3 Winter

Copper Corrosion

@ 100 degree C for 3 Hrs - - - P;15 1 max

Density @ 15 degree C kg/M3 P:16 820-860

Contd...

Notes

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Contd...

Distillation

Recovery at 350 degree C % v P:18 85 min

Recovery at 370 degree C % v P:18 95 min

Flash Point degree C P:20 35 min

Kin Viscosity @ 40 deg C cST P:25 2.0 to 5.0

Sediments % w P:30 0.05

Total Sulphur % w P:33 0.25

Water Content % v P:40 0.05 max

CFPP deg C P:110 6 Winter

18 Summer

Total Sediments mg/100 ml UOP 413 1.5 max

Lubricity HFRR Scardia

Micron at 60o C, 400 Proposed

Light Diesel Oil (IS 1460 - 2000)

Test Unit Method Requirement PSS

Acidity Inorganic mg KOH/Gm P:2 Nil - - -

Ash % w P:4 0.02 max 0.005 max

RCR on whole sample % w P:8 1.5 max 0.3 max

Pour Point deg C P:10 12 Summer 0 max

21 Winter 0 max

Copper Corrosion

@ 100 deg C for 3 Hrs - - - P:15 2 max 1b

Flash Point (PMCC) deg C P:21 66 min 66 min

Kin Vis @ 40 deg C cST P:25 2.5 to 15.7 2.5 to 5.0

Sediments % w P:30 0.1 Max 0.05 max

Density @ 15 deg C kg / M3 P:16 Report 910 max

Total Sulphur % w P:33 1.8 max 0.35 max

Water content % v P:40 0.25 max 0.05 max

Petroleum Coke (IS 8402 - 1994)

Test Unit Method Requirement PSS

Moisture as Received % w P: 132 10 max 8 max

Moisture after

Initial drying % w P: 132 2.0 max - - -

Ash on Dry basis % w P: 126 0.45 max 1.0 Max

Volatile Matter % w P: 134 11 max 8 max

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Density (Dry) kg/ M3 P: 133 Report 560 min

Fixed Carbon

(On Dry Basis) % w Calculation 85 min 88 min

Total Sulphur % w P: 33 2.5 max 7.0 max

Trace metals

Silicon as Si ppm w UOP 389 Report 150 max

Iron as Fe ppm w 150 max

Vanadium as V ppm w 1600 max

Nickel as Ni ppm w 400 max

Hardgrove Grindability

Index ASTMD 4097 50 MIN

GCV Kcal/ Kg - - - 8000 min………….

Properties of Petroleum Products and theirSignificance

Gasoline

Effect of Chemical Composition on Gasoline Quality

Octane number is the most important property of motorgasoline. Composition of motor gasoline profoundly affectsits performance in the engine and equally controls itsbehaviour under storage and handling.These are describedbelow:

Paraffins (Cn H

2n+2)

– Thermally and chemically most stable compounds.

– Have poor octane number

– Increasing the chain length reduces the octane number

– Knock resistance increases with branching

– Adding methyl groups (CH3) to the side chain in thecentral position increases the knock resistance

Olefins (Cn H

2n)

– Oxidation and thermal stability is poor in general

– More knock resistance than their correspondingsaturated compounds.

Notes

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Cycloparaffins (CnH

2n)

– Poorer knock resistance than corresponding aromatics

– Lengthening of side chain decreases knock resistance

– Branching of side chain is beneficial.

Aromatics (CnH

2n-6C

nH

2n-12 etc)

– Aromatics have excellent knock resistance qualities.

Properties of Gasoline and Oxygenated Compounds

Gasoline Properties Needed for Acceptable Performance

Combustion and Knock

Before combustion, air and fuel is heated up in combustionchamber, there is an induction period before normal hot

Property Methanol Ethanol Isopropyl Alcohol

Tertiary Butyl Alcohol

MTBE Gasline

Chem.

Formulae

CH30H C2H5OH C3H70H C4H90H C4H9OCH3 C8H15 (Av.)

Mol. Wt. 32 46 60 74 88 111

Oxygen

Cont. % mass

50 35 27 22 18 0

B.P.ºC 65 78.3 82.2 82.8 55 30-20

Stoichio-

Meteric A/F

6.4 9.0 10.3 11.1 11.7 14.6

Lat. Heat of Vap. Btu/Gal (J/lit)

3300

(11.8)

2600

(9.3)

2100

(7.5)

1700

(6.1)

900

(3.2)

800

(2.9)

Net Heat comb. MJ/Kg

21 28 32 35 35 43

Solubi-Solubility in water, g/100g water

∞ ∞ ∞ ∞ 4.8 Trace

RON

MON

107 108 112 113 116 87-93

- - - - 101 82-87

Fuel Performance Required Property Controlled for Automotive Gasoline

Handling and Storage Volatility Vapour Pressure Contamination (Water/Sediments/Gum)

Copper Corrosion

Combustion Octane Number Volatility/Distillation Range Gravity

Engine Cleanliness Hydrocarbon Compostion

Sulphur

Existent Gum

Oxidation Stability

Notes

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flame occurs. During this induction period, oxidation of fueltakes place with the formation of intermediate products suchas peroxides, aldehydes and peracids. Formation ofperoxides, aldehydes and peracids prevents knock due totheir ability to dissociate and promote such type ofintermediate reactions.

Knocking Tendency

High Anti-knock Value: Aromatics, Isoparaffins (highlybranched)

Intermediate Anti-knock Value: Mixed parffins e.g.isoparaffins with little branching, Naphthenes.

Low Anti-knock Value: Paraffins

Combustion Chamber Deposits

Deposits are formed by

– Incomplete Combustion

– Partial Oxidation

– Cracking

– Condensation and Polymerisation of fuel andlubricants

– May contain nonvolatile reaction products ofadditives

Deposits can lead to:

– Pre-ignition

Peak pressure and temperature will increase due toapparent increase in compression ratio and poor heattransfer due to heat insulation effect.

– Loss of power due to reduction in volumetric efficiency

– Exhaust valve corrosion

– Spark plug fouling

Notes

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Volatility

Volatility of gasoline is its tendency to pass from liquid tovapour phase. Volatility influences:

– Ease of starting

– Rate of warm up and acceleration

– Tendency to vapour lock

– Carburettor icing

– Crankase dilation

– Fuel economy

Ease of Starting

For a cold engine start, enough gasoline in the intake airmust be evaporated. Ease of starting depends on:

y Fuel volatility

y Engine design

y Cranking speed

y Engine oil viscosity

Warm Up and Acceleration

It depends on:

1. Fuel volatility and ambient temperature

2. Provision for thermostatical controlled hot spots. Warmup is mainly a cold weather problem.

Vapour Lock and Percolation

Vapour lock is a function of :

1. Volatility characteristics of fuel

2. Fuel requirement of engine at the moment

3. Ability of fuel pump to handle the vapour

Notes

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4. The temperature and pressure in the fuel system

5. The temperature of ambient air, underbonettemperature and barometric pressure.

Measurement of Volatility

1. ASTM D-86 Distillation

Significant temperatures are

– Initial boiling point

– Temperature corresponding to 10% Vol.



– FBP

– Non-volatile residue left in the flask.

2. Reid vapour pressure (RVP)

Controls the volatility due to lighter ends.

TYPICAL VALUES OF VAPOUR PRESSURES

(RVP)

3. Vapour lock index (VLI)

10 RVP+ E 70

Gives better indication of vapor locking.

Carburetor Icing

It occurs due to following:

– Stoppage of the fuel flow due to clogging of the jetice

– Formation of ice on the walls of carburetor ventenarywhich causes the engine to stall due to over-rich fuel/air mixture

K g /c m 2 P S I K P a

P ro p a n e 1 4 .1 2 0 0 1 3 8 2 .8

B u ta n e 5 .6 8 0 5 4 9 .2

M o to r G a s o lin e 0 .7 1 0 6 8 .6

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– High volatility of fuel

– Cold and humid climate are favorable for icing.

Remedial Measures

– Control of fuel volatility

– Providing heating of carburetor body or the intake air,particularly during warm up period

– Providing greater throttle opening during starting

– By incorporation of anti-icing agents

l Anti-freeze type

l Surface active agents

Oxidation Stability

Gum formation takes place in storage due to oxidation/polymerisation reaction undergone by the unsaturatedhydrocarbons and it accelerates at higher temperatures.

Gum is a rubber like resinous material and is insoluble inlater stage of formation. Sulphur and nitrogen compoundsalso take part in these reactions

Gum formation is influenced by storage conditions,temperature, access of air and light, and catalystsparticularly traces of copper.

Impact of Gum Formation

y May cause intake valve sticking due to deposition ofGum, and may lead to valve burning

y May cause malfunctioning of carburetor float or impairthe functioning of throttle

y Deposits formed in the intake may restrict enginebreathing and reduce the efficiency of hot spots resultingin increased warm up period

y It can lead to increased sludge and varnish deposits inthe engine.

Activity 3 C

How is gum formed in motor spirit,what is its impact and how is itovercome?

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Sulphur Compounds and Corrosiveness:

Most of the sulphur compounds are removed in themanufacturing processes. If these H2S and COS are mainlycorrosive and RSH is distinctively unpleasant.

Sulphur, on oxidation, forms oxides of sulphur which reactwith water to form sulphuric acid.

A direct result of leakage of unburnt fuel can be corrosion ofengine parts.

Stringent specifications are required to be followed due toenvironmental considerations.

Automotive industry requirement for meeting Euro III/IV emission standards for Motor Gasoline.

RON MON

89 79 to continue for old cars

91 81 to be widely available

93 83 to continue for high CR cars

Benzene content 1% Max

Aromatics 40% Max

Olefins 25% Max

Lead Content 0.005% Max

Sulphur Content 0.05% Max

Oxygen Content 2.70 Max

Diesel Fuels

BIS Grades of Diesel Fuels

There are three grades of diesel:

– High Speed Diesel (HSD)

– Light Diesel Oil (LDO)

– Marine Diesel (MD)

Notes

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HSD Blending Components (Typical)

B0ILING RANGE ºC CETANE NUMBER

Heavy SR Naphtha 148-204 28-42

Kerosine 204-260 45-50

LT. SR Gas Oil 250-315 45-50

Heavy Gas Oil 315-350 50-55

LT. Cycle Oil 204-343 15-20

Hydro Cracker Go 204-343 50-60

Coker Kerosene 204-340 15-20

FUEL Performance Requirements

Effect of Diesel Fuel Hydrocarbon Type Composition on itsQuality

Paraffins

– Have the best combustion characteristics and highestcetane numbers

– With molecular weight of n-parrafins, cetane numberincreases

– Isoparaffins have lower cetane numbers than theparaffins of same carbon numbers. With branchingcetane number is lowered.

Olefins

– Olefins have lower cetane numbers than paraffins ofcorresponding structures and follow similar rules ofbranching

Notes

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Handling & Storage - Volatility

- Flow

- Corrosive constituents

- Contaminants

- Flash Points

- Viscosity

- Water & sediments

- Copper corrosion

- Cloud/Pour pt.

- CFPP

Combustion - Ignition Delay

- Volatility

- Heat content

- Cetane Number

- Distillation Range

- Gravity

- Cloud & Pour Point

Cleanliness During Use

- Heavier constituents

- Metals

- Corrosive constituents

Carbon Residue on 10%, Bottom Ash Content, Sulphur Content, Stability Exhaust Emission Standards



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– Presence of olefins gives rise to poor oxidationstability.

Naphthenes

– Naphthenes follow olefins in cetane quality but are agood deal higher than aromatics.

Aromatics

– Impart lowest cetane number and most important factorcontrolling the cetane number of cracked gas oil

– Aromatics ring condensation and the side chainbranching on rings that cause molecular configurationof lowest cetane numbers.

Ignition Quality

This is the most important property that controls combustionprocess. It is measured as a cetane number which is ameasure of ignition delay and is controlled by

– Fuel composition and characteristics

– Engine design

– Fuel and air inlet temperature

– Degree of atomisation.

As a result of abnormal ignition delay, large quantities of oilare gathered in the combustion chamber. Spontaneousburning and detonation of this surplus fuel in combustionchamber causes rough ignition which is termed as dieselknock or cetane knocking.

Cetane Improver Additives

Base Diesel Cetane No. 44

Additive dozes 1.5% Increase in CN

Isoproyle Nitrate 17

n – Amyl Nitrate 23

Notes

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Cyclohexyl Nitrate 22

Octyl Nitrate 19

Flow Properties

Viscosity

u Viscosity of diesel fuel has an effect on handling of thefuel by pump and injector system.

u High viscosities can cause

– Poor atomisation

– Large droplets

– High spray jet penetration

u Low viscosity results in a spray which is too soft andthus does not penetrate sufficiently. As a resultcombustion is impaired and power economy isdecreased.

u Lubricating oil properties of such fuels are usually poor

u HSD viscosity range is generally 2.0 to 5.0 cst.

u Heavy distillates, when used as diesel fuel, are generallypreheated.

Cloud Point

u Congealing wax settles out and blocks fuel system lineand filters.

u The temperature at which precipitation occurs dependson the composition and boiling range of the fuel.

u Cloud point indicates the temperature at which waxesstart precipitating.

Cold Filter Plugging Point (CFPP)

u Cloud point being a static test does not truly representactual running conditions.

u CFPP is defined as highest temperature expressed asa multiple of 1oC at which the fuel when cooled

Notes

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under prescribed conditions will not flow through afilter or requires more than 60 sec for 20 ml to passthrough.

Pour Point

u Pour point gives a useful guide to the lowesttemperature at which the fuel can be cooled with setting.

Cleanliness in Use

Carbon Residue

u Gives some indication of coke forming / deposit formingtendencies in the engine.

u Deposits are mainly carbonaceous matter, ash,resins etc.

u Type of deposits is also an important factor. Hardabrasive deposits can do more harm than soft fluffydeposits.

u The test can also be used to detect contamination byheavy residues.

u Maintenance life and period of over-haul mainlydepends on deposit control.

Ash Content

u Indicates the presence of small quantities of metallicsoap or volatile porphyrines.

u Unburned metallic constituents have abrasive actionand cause wear by adversely affecting the nature ofdeposits.

Water and Sediments

u These may come into the fuel through contaminationduring storage and handling.

u They can cause clogging of filters.

u Sediments cause wear and create deposits both in theinjection system and engine itself.

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Sediment and Gum Forming Reactions (Diesel FuelStability)

1. Oxidative Gum Reactions

Alkenee + Oxygen ….. Gum

Reaction time ….. Weeks to months

2. Acid – Base Reactions

Organic acid + Basic Nitrogen …… Sediments

Reaction Time …… Hours to weeks

3. Esterification reactions

Aromatic Hydrocarbons + Hetrocylic Nitrogen +Benzothiols

Multi-step Process …… Sediments

Reaction Time ….. Weeks to months

These are more predominant in diesel fuel instability.

Corrosive Constituents

Sulphur Content

u Strict emission regulations require stringent sulphurspecifications

u Due to high sulphur, combustion products corrode andalso contribute to deposit formation.

u Low speed diesel engines can tolerate more sulphur,because

– They are large in size and are stationary

– They are high power output type

– They run under relatively constant speed and loadconditions

– Their operating temperatures, cooling water andcombustion zone temperatures tend to remain at

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an equilibrium rather than to fluctuate betweenhigh and low.

Tests carried out

u Estimation of sulphur content

u Copper strip corrosion test.

Acid value

u Total and Inorganic

u Potentiometeric Acid/Base titration

Residual Fuels Oils

Changes in quality of fuel oils in Indian refineries aredue to:

u Frequent changes in crude quality and blend ratios

u Intake of more of heavy crudes

u Introduction of various secondary conversion processesfor maximisation of middle distillates.

Components of Residual Fuel Oils

u Long residue

u Short residue

u Heavy cycle oil, clarified oil from FCC

u Hydrocracker bottoms

u Visbroken products

u TAR from thermal conversion process

u Slop

Uses

u Steam boilers

u Industrial applications requiring heat

u Gas turbines

u Diesel engines

Notes

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Summary of Fireside Problems Related to Fuel Quality

Effect of Sulphur

u Raises dew point of fuel gases

u Increases formation of sulphur deposits in boilerpassages, economiser, air–preheater and chimney

u Reduces efficiency by reducing permissible temperature

u Accelerates formation of gum and sediments duringstorage

u Corrosion of process and plant equipment

u Sulphur pick by product.

Effect of Metals

u Vanadium is a major metallic impurity in residual fueloil. Causes corrosion in high temperature zone.

u Sodium is recognised as a potential corrosion problem.

u In combustion,

Na converts to Na2O + Na2SO4

V converts to V2O5 + V2O4

® Na2 V2O5, Na2 V2O4 5V2O5

(Low melting ash deposits)

u Other ash deposits are SiO2, AI2O3, Fe2O3

NaAIO2 has high melting point (3272 oF). It causes metalspalling or breaking off of pieces of refractory due to its highthermal expansion.

Problems Causes Solutions

Plugging of fuel lines strainer and burner tips

Oxidation of the fuel to produce acid and sludge

Addition of inhibitors and sludge dispersants

Fuel system corrosion Acidic, sulphur compounds, water, sludge

Application of corrosion inhibitors

High temperature fouling & corrosion

Na, V in fuel form low melting point sulphated ash

- magnesium additives

- reduce excess air

- combination of both

Activity 3 D

Effect of metals in furnace oil?

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Review Questions

1. What is the significance of following tests and to whatpetroleum product these are related:

- Flash point

- Distillation

- Smoke point

- Octane number

- Cetane number

- Viscosity

- Silver corrosion

- BMCI

- Weathering test

- Copper corrosion

- Vapour pressure

2. What specifications for Motor Spirit and HSD arerelated to environmental pollution? What are the limitsfor these specifications for Euro III / IV standards?

3. What strategies are being adopted to improve thesespecifications to desired ones from the present values?What would be the impact on cost of production? (ReferBibliography)

4. What streams of Process Plants in a Refinery areutilised to produce HSD, MS, LPG and PC Naphtha?(Refer Unit 4 & Bibliography).

Notes

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Unit 4

Integrated Refinery andPetrochemical Plants

Now a days, to minimise processing cost and optimise productdistribution, emphasis is laid on the following:

1. Economies of scale – Minimum 9-12 MMTPA refiningcapacity.

2. Refining and petrochemical plants are integrated.

3. Feedstock flexibility – To utilise low cost crudes.

4. Supply chain optimisation from crude to products,provides faster delivery and at lower cost.

A typical integrated refinery and petrochemical plant setup is shown in attached block flow diagram. (Fig. 4.1)

Crude is normally received by tankers or pipelines into crudetanks and allowed to settle for separation of water andsludge. Then it is taken to Crude Distillation Unit (CDU)which operates at atmospheric pressure for fractionationinto Gas, LPG, Naphtha, ATF, Kerosene, MTO, Diesel, JuteBatching Oil (JBO) and Reduced Crude Oil (RCO). RCO isfractionated in Vacuum Distillation Unit (VDU) to get VGOand raw lube cuts. The raw streams from CDU are treatedin Merox, Hydrotreatment, Reforming, Isomerisation andFluid Catalytic Cracking plants to obtain components of

53

Objectives


y Understand the functioning of various process plants in a refineryand their integration with one another.

y Give insight into the feeds composition of various process plantsfor production of finished products.

y Give an overview of various off-site facilities in a Refinery.

Notes

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finished saleable products. VGO is treated in FCCU to getLPG, Propylene, Petrochemical feedstocks and componentsfor motor spirit and diesel. Raw lube cuts are treated forremoval of aromatics and wax and are hydrotreated to getlube oil base stock. The short residue obtained from VDUfractionator bottom is partly treated in coker unit to getlighter value added products alongwith raw petroleum coke.Vacuum residue can also be treated to extract outDeasphalted Oil (DAO) and the residue left is asphalt. DAOis treated in aromatic extraction unit, dewaxing unit andhydrofinishing unit to obtain bright stock which is used forLube oils and grease manufacture. Asphalt and vacuumresidue can also be utilised for production of bitumen or asfuel for furnaces and boilers. From FCCU, olefins, propylene,various aromatics and naphthas are obtained which are usedas raw materials for polypropylene and aromaticpetrochemical plant. The Raw Petroleum Coke (RPC) is usedfor generation of power and calcined petroleum coke. Sulphurpresent in crude and various streams is converted to H2Sduring processing. In Sulphur plant, it is converted toelemental sulphur which is sold as by-product. This also helpsin environmental protection. Hydrogen plant is installed toproduce hydrogen for meeting the requirement of variousHydrotreatment processes.

FIGURE 4.1 INTEGRATED REFINERY AND PETROCHEMICAL BLOCKDIAGRAM

FCC Aro

PP

MPP

Coker

Sulfur

CDU/ VDU

CRUDE TANKS

CRUDE

Propylene

Naphtha

Kerosen

Petro

Diesel

LPG

Paraxylen

Polypropelene

Power

Kerosene

Gasolene

e

Notes

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Crude Distillation

Brief process descriptions have been provided (please referblock flow diagram of CDU, VDU and SGU). This part hasthree main sections.

1. Desalting

2. Distillation-Atmospheric & Vacuum

3. Saturated Gas Concentration Unit (SGU)

FIGURE 4.2 BLOCK FLOW DIAGRAM OF CDU/VDU/SGU

FIGURE 4.3 CRUDE AND VACCUM DISTILLATION UNIT IN A REFINERY

Lean Gas

LPG to Marox

Naptha to Hydrotreater

LK/ATF

Other streams from other limits

S G C

HK

Diesel

JBO

Fumace

V a c. C o l.

LVGO

HVGO TO FCC

Vacuum Residue to Belayed Coker/ Bitumen.

Atmospheri

c Col.

Desalter

F u r n a c e Preheat 3 Preheat 1 Water in Brine Out

Flash Drum

Crude in

Preheat 2

Lubedistillates

Notes

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Desalting

The crude oil is contaminated with various impurities–mainly salts of Ca, Mg, Na, CI, SO4, etc. These salts, however,in small proportions in crude, can cause severe corrosion incrude units, particularly in the overhead section. Severalrefineries worldwide have faced emergency shutdowns orhave had to release hydrocarbons due to corrosion andmaterial failures. Hence, it is important to remove the saltsfrom crude prior to distillation. The desalters are designedfor 99% salt removal and reach less than 1 ptb (part perthousand barrels) in desalted crude.

Crude oil received from tank farm is heated from 30 to 140-150ºC in cold preheat trains. This is done by recovering heatfrom outgoing products streams from the unit. This preparescrude for efficient desalting. Then it is passed through adesalter after being mixed with de-emulsifier and waterthru a mixer valve. In the desalter, crude passes throughhigh electric field. The salt dissolved in water settles at thebottom as brine and desalted crude with less than one partsper thousand barrel comes out from the top of the vessel.Separation of water containing salt is enhanced by de-emulsifier. Desalters remove salts, sludge and mud fromcrude to avoid corrosion and fouling in exchangers columnsand downstream equipment.

Distillation � Atmospheric & Vacuum

The desalted crude is then heated from 140º to 190º C at 25Kg/a2 pressure by heating with a heavier hot stream. Thenit is taken to the flash drum. From the top we get lightercomponents which directly go to the crude column. Theflashed crude is passed through hot preheat exchangers andfurther heated from 190°C to 250–260°C. The purpose of hotpreheat train is to recover heat from pump arounds to reducefurnace duty. Furnace provides required heat forfractionation in atmospheric column and crude is heated upto385°C.

The heated crude is fractionated in atmospheric distillationcolumn of CDU. The fractions below 165°C are withdrawnas column overheads and sent to SGU. Here mainly gases,LPG and FRN are separated. Heavies boiling at more than

Notes

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386º C are reheated under vacuum condition (to avoidcracking) and fractionated in vacuum column of VDU.

Besides the straight run products such as LPG, Naphtha,LK, HK and Diesel, the other distillation products areintermediates viz. (1) Gas Oil (HAGO+LVGO+HVGO) whichbecome feedstock for FCC after treatment in VGOHT and(2) VR which becomes feedstock for delayed coker. The LPGis sent to LPG Merox unit for treatment before sending toRTF. The FRN is directly sent to the HNUU in the aromaticscomplex. The Light Kero (LK) fraction is routed as SKO toRTF directly or via Kero Merox unit as ATF. The Heavy Kero(HK) fraction is blended with diesel fraction. The dieselfractions can be routed to DHT or RTF as required.

Saturated Gas Concentration (SGU)

The overhead liquid and gases from CDU, reformer andhydrotreaters of petro-chemical complex are passed throughthis plant to separate into following fractions:

1. Gases (C1+C2) for burning into furnaces or aspetrochemical feedstock after H2S is removed in AmineTreating Unit.

2. LPG (C3+C4) for domestic and industrial use afterremoval of Mercaptanes in Merox Unit.

3. Naptha (C5 to 165ºC) for sending to fertilizer orpetrochemicals plants as feedstock.

The typical streams obtained from crude oil by Atmosphericand Vacuum distillation are given in the following table:

% of crude input Cut range deg C Fuel Gas 0.01 to 0.03% < C2s

LPG 1.0 to 1.5% C3–C4s FRN 11 to 14% C5s to 16s

LK / ATF 10 to 11% 165 – 227 HK 6 to 7% 227 – 270 Diesel 16 to 17% 270 – 370 HAGO 2.5 to 3.0% 370 – 392 RCO (Atm. Residue) <392 LVGO 2.5 to 3.5%

HVGO 21 to 22% VR 23 to 26%

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Product specifications and significance of the same isgiven in Unit 3

Operating issues which need attention are:

1. Crude mix and product yield pattern

2. Corrosion impact on various equipment should beknown.

3. Health of equipment and run length of unit is vital.

4. Operating parameters such as pressure, temperature,flows.

5. Quality control of crude and products.

6. Health, safety and environment (HSE) aspects.

7. Energy conservation

8. knowledge and skills of operating crews.

Diesel Hydro-Treatment

The purpose of diesel hydrotreating unit is to:

u Remove sulphur and nitrogen

u Convert olefins/aromatics to saturated compounds.

u Remove contaminants like oxygenates andorganomettalic compounds.

The catalysts used in this plant are oxides of Ni and Mo/Co& Mo impregnated on alumina base.

Salient Features

u 98% desulphurisation and 70% denitrification (VGOhydrotreater).

u Produce low sulphur, colour stable diesel.

u Reduce aromatics and nitrogen in diesel.

u Improve Diesel cetane no.

The feed to the unit consists of a mixture of SR dieseland heavy kerosene from the Crude Unit, light coker

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gas oil, HCO from the Delayed Coking Unit and LCO fromFCCU

Diesel Hydrotreater

FIGURE 4.4 HYDROTREATER BLOCK-FLOW DIAGRAM

Brief Description of the diesel hydro-treater follows.

The feed is pumped through cold and hot feed-reactoreffluent exchangers and then with recycled gas streamsthrough the combined feed heater. The combined feed heaterheats the feed up to the reactor inlet temperature. Thereactor consists of one vessel with two beds of catalysts,consisting of one inert and three different types of catalysts.Recycled gas is added as a quench between the beds to quenchthe top bed heat of reaction. The reactor effluent is cooledthrough a series of heat exchangers where it, in turn, heatsup the fresh feed, the stripper feed, the recycled gas andthen provides heat for generation of HP, MP and LP steam.

A wash water stream is then injected into the reactor effluentbefore final cooling in the air-product condenser. From theproduct condenser, the reactor effluent enters the separator.The separator is a horizontal vessel with a water boot thatseparates the recycled gas from the stripper feed and thewash water from the stripper feed. The recycle gas goesthrough a recycled gas water cooler and knockout drum toremove heavier hydrocarbon components before entering the

Ovhd. condensor

Offgas to SGCU

Diesel

VGO

LN

Stripper

To waste water system

Hydrotreater

Diesel

VGO

LN

Recycle gas

Make up H2

Product separator

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recycled gas scrubber. This scrubber is used to remove H2Sfrom the recycled gas by bringing it in contact with a liquidstream of lean amine. The top of the vessel contains a waterwash section to pick up any entrained amine. The recycledgas exits from the top of the recycle gas scrubber, and isthen mixed with makeup gas hydrogen before entering therecycle gas compressor. The stripper feed is heated in aseries of exchangers where it in turn cools the stripperbottoms, reactor effluent, before entering the strippercolumn.

The stripper is used to remove H2S from the diesel product,and also to separate unstabilised naphtha from the dieselproduct. Both the net off gas and the unstabilised naphthaliquid that are produced are routed to the Saturated GasConcentration Unit. The stripper bottom is cooled througha series of exchangers, then further cooled by air and waterbefore entering the diesel product coalescer and the saltdrier which removes water prior to routing to the dieselproduct blending system.

VGO Hydro-treatment

This is similar to diesel hydro-treater and is used forpreparing feed for FCC.

FIGURE 4.5 HYDRO-TREATER/ HYDRO-CRACKER IN A REFINERY

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Hydrogen Production and Management

Hydrogen Production Plant

Hydrogen is produced commercially using followingtechnologies:

(i) Partial oxidisation

(ii) Coal gasification

(iii) Electrolysis of water

(iv) Steam hydrocarbon reforming

(v) Platforming – as a by-product.

Refer hydrogen plant block flow diagram

FIGURE 4.6 HYDROGEN PLANT BLOCK FLOW DIAGRAM

Hydrogen Feed

Feed for hydrogen production plant — (i) Refinery fuel gas,(ii) saturated LPG, (iii) Natural gas, (iv) Light Naphtha.

Process Description

Feed (Refinery Fuel Gas, or Natural Gas or LPG or Hydro-treated Light Naphtha) is first mixed with recycle hydrogenand passed through pre-treatment section. The function ofpre-treatment section is to remove sulphur in feed byhydrogenation, in the form of H2S, and removal of chlorideby sodium aluminate, the catalyst used is CoMo or NaMo.H2S is absorbed in Zno bed.

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Recycle H2

HP BFW HP steam export

Refineryfuel gas

Natural gas

ProductH2

Waste gasRefinery general

fuel gas

SteamGenerator

Steamreformer

Feedpurification

Shift & gascooling

Feed gascompr. Gas

purification

Main pumping section

Naphtha(future)

LPG

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If sulphur is <200 ppm, then single stage pre-treatment isadopted. For sulphur >200 ppm, double stage pre-treatmentis used.

The De-sulphurised feed is pre-heated with steam andpassed through Nickle Catalyst packed in Vertical narrowtubes mounted in the reformer furnance. This process isendothermic and heat is supplied by fuel firing. Followingreactions take place:

Steam Reforming

CH4 + H2O l 3H2 + CO

CO + H2O l H2 + CO2

Water Gas Shift

CO + H2O l H2 + CO2

Steam is added in excess to promote above reactions.Hydrogen gas produced is purified by pressure swingadsorption (PSA) method.

PSA Cycle

One PSA cycle is built up of 2 basic phases:

Adsorption and Regeneration

Regeneration of PSA Bed

The regeneration phase is a chain of sub-phases consistingof:

l High to low pressure transition: Expansion

l Provide purge and dump

l Purging at low pressure

l Low to high pressure transition back to adsorptionpressure: Repressurization.

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Hydrogen Management

Hydrogen gas in the refinery comes from

(i) Hydrogen production plant – as described above

(ii) Catalytic reformers

- in the refinery

- in the integrated petro-chemical plant

The hydrogen from both the sources is supplied to variousconsumers like hydro-treatment plants etc. through highpressure compressors and the excess gas is led to refineryfuel gas system.

Need of hydrogen is increasing day after day for treatingthe products like motor spirit, HSD, fuel oils and feeds forFCC and other plants for bringing down sulphur.

Merox (Mercaptan Oxidation) Treatment

Process Description

Merox is the abbreviation of Mercaptan Oxidation. In thisprocess mercaptan is separated from hydrocarbon bywashing with caustic solution. The separated merceptan isoxidised into disulfide form which can be disposed of in slopstream. Organic sulphur from LPG, ATF/Kerosene andGasoline are removed by this process.

Hydrogen Sulfide (H2S) from LPG is removed by extractionwith regenerated lean Amine in Amine Treating Unit (A TU).Treated LPG is passed through reactor and mixed withcaustic solution containing merox catalyst. Then it passesthrough extractor to remove mercaptan. Then, it is washedwith water to remove caustic. Treated sweet LPG free ofH2S and Mercaptan is sent to storage.

In case of ATF/Kerosene and Gasoline treatment, first it ismixed with caustic, air and catalyst and then passed toreactor to convert mercaptanes to Disulfides, which isseparated from caustic and product in caustic sulphur.Caustic in recycled. Sweetened product is stored inintermediate tanks before blending into finished product.

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Following reactions take place

Mercaptan gets converted into disulfides

4RSH + O2 2RSSR + 2H2O

Caustic Regeneration

RSH + NaOH NaSR+ H2O(oil phase) Aqueous (Sodium Mercaptide soluble in

phase Aqueous phase)

Catalyst4NaSR+02+2H2O 2RSSR+4NaOH(Aqueous Phase) 45ºC (oil Phase)

The purpose of caustic in Merox process is:

u To transfer the mercaptane, or the thiol portion of themercaptane, to the aqueous phase.

u To supply the alkaline environment needed for thereaction to proceed in the desired direction.

FIGURE 4.7 MEROX TREATMENT PROCESS BLOCK FLOW DIAGRAM

This process is used for treating LPG, Gasoline and ATF.

Sulphur Recovery Plant

The objective of sulphur recovery plant is to convert H2S toelemental sulphur.

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Sulphur recovery is required because of:

l Increasing demand for environmental friendly fuels.

l Increased used of high sulphur and heavier crudes infuture.

l Tightening of emission standards by government/Regulatory bodies.

Salient features of sulphur plant are:

l Minimum sulphur recovery level of 98.7%

l Ammonia destruction capability

l Turndown capability 25%

Process Description

Refer sulphur plant block flow diagram (Figure 4..8)

Acid gasses from Amin Recovery Unit (ARU) and sour gassesfrom sour water stripper are heated in pre-treater and burntin presence of regulated quantity of air from CLAUS AirBlower in CLAUS Reaction Funance. The product from clausreaction funance is passed thru 1st and 2nd pass condensers.

.

FIGURE 4.8 SULPHUR PLANT BLOCK FLOW DIAGRAM

The sulphur condensed is routed to Liquid SulphurDegassing Pit. The unreacted vapour is passed thru clausreactor. The vapour from the claus reactor outlet is passed

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Air

Acid gasesfrom ARU

Thermal reactor Claus reactor CBA reactor

Air

Condenser 1 Condenser 2 Condenser 3 To tail gasincinerato

To sulphurgranulation unit

Liquid sulfurdegassing pit

Sour gasesfrom WWSU

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thru 1st and 2nd pass condensers. The condensed sulphur istaken to Liquid Sulphur Degassing Pit. The uncondensedvapour is passed through Cold Bed Adsorption (CBA)Reactors 1st and 2nd passes. The outlet vapour is passedthru 1st and 2nd pass of CBA condenser. The condensedsulphur is routed to liquid sulphur degassing pit and theremaining gases are taken to tail gas incinerator for burningand releasing thru high stack. Sulphur after Degassing istaken to granulation unit from where it goes for despatch tomarket. The off-gases from sulphur degassing pit is recycledto CBA section for recovery of sulphur.

What is Claus Reaction?

“When two molecules of Hydrogen Sulphide (H2S) react withone molecule of Sulphur Dioxide (SO2) to give elementalsulphur in the presence of Alumina Catalyst, the reaction iscalled Claus Reaction”

2H2S + SO2 3/nSn + 2H2O

n=No. of atoms in Sulphur molecule.

u 1/3rd of total H2S in feed gas is burned to SO2, this SO2

reacts with remaining H2S to give elemental Sulphurin Claus Reactor

H2S+3/202àSO2+H2O2H2S + SO2à3/n Sn+2H2OOverall Reaction 3H2S + 3/2 O2à3/nSn + 3H2O

Process Variables

Air to Acid Gas Ratio H2S/SO2 Ratio = 2:1

u Claus Reactor Outlet Temp 344ºC

Incinerator Temperature 650+ –50ºC

Amine Treating Unit (ATU)

The purpose of this process unit is to remove H2S from fuelgases to meet environmental requirements.

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Process Description

Refer figure 4.9 simplified block flow diagram

The fuel gas containing H2S is introduced in Middle sectionof Amine Absorber Column where Lean Methyl Diethanol isintroduced near top section. By counter current flow H2S isabsorbed in Amine and sweet fuel gas (FG) free of H2S comesout from column top. The rich Amine from bottom of theabsorber column is taken to Flash Drum where any fuel gascarried over is separated out. The rich Amine is then pumpedthrough heater where it is heated by the hot lean aminestream coming from bottom of Amine stripper. In thestripper, Amine Acid Gas from top of the column is routedto sulphur recovery plant along with sour gases from otherprocess units. The lean Amine from bottom of the stripperexchanges heat with Rich Amine and then pumped to storagetank through cooler for recycling to Amine Absorber.

FIGURE 4.9 SIMPLIFIED BLOCK DIAGRAM – ATU

Process Chemistry

The circulating amine is 35% MDEA solution,

Hydrogen sulfide H2S OR HSH is a weak acid and ionizes inwater to form hydrogen ions and sulfide ions.

HSH H+ + SH–

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Absorption Section

FG Abs Stpr

Regeneration Section

Rich Amine Header Amine Storage Section

Lean Amine Header

Lean Amine

Sweet FG

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Ethanol amines or weak bases ionize in water to form amineas hydroxyl ions

(CH2OHCH2)2NCH3+H20 CH2OHCH2)2NHCH3+OH

When H2S dissolves into the solution containing the amineions, it will react to form a weakly bonded salt of the acidand the base.

(CH2OHCH2)2 NCH3+SH (CH2OHCH2)2NSCH3

The sulfide ion is absorbed by the amine solution. Overall

(CH2OHCH2)2NCH3+H2S (CH2OHCH2)2NSCH3

Delayed Coking

Coker Unit

The purpose of coking unit is to produce valuable distillatesand Petroleum coke (by-product) by upgrading heavy residualstocks from vacuum distillation and other process unitsgenerating heavy stock. This unit is also known as delayedcoker. Slops from various other process units which do notfind proper home can also be processed in coker to getvaluable products. The feed to this unit is subjected to severethermal cracking thereby producing refinery fuel gas, cokergasoline, coker kerosene, coker gas oil, coker furnace oil,residual furnace oil and coke.

Process Description

Refer block flow diagram of coker

Feed is preheated by exchanging heat with hot streams.Thereafter, it is heated to 250ºC in convection section of thefurnace before it enters the bottom section of fractionatorcolumn. The hot cracked hydrocarbon vapours from cokechambers top via a separator enters the zone of above-mentioned fractionator column. The heavy hydrocarbonfractions in these vapours condense in lower section of thecolumn and are withdrawn from bottom along with primaryfeed by secondary feed pump.

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FIGURE 4.10 COKER BLOCK FLOW DIAGRAM

The secondary feed is heated in the remaining part ofthe convection section and full radiation section of thefurnace to around 500ºC and enters the coke chamberswhere final cracking takes place. The vapours from top ofthe coke chambers is quenched with cold vacuum distillatesbefore it enters the separator. The liquid productaccumulated at separator bottom is pumped out as ResidualFuel Oil (RFO).

The vapour is routed to bottom of fractionator as mentionedearlier. From the fractionator, products withdrawn are LightKerosene (LK), Heavy Kerosene (HK), gas oil and cokingfuel oil (CFO). Fractionator vapour top is condensed in overhead condenser to produce gas and coker gasoline and cokernaphtha (light coker naphtha and heavy coker naphtha). Thepetroleum coke is accumulated in coke-chamber, is cooledby steam and water and thereafter removed by hydraulicde-coking method which cuts the hard coke with highpressure water jets. The coke is removed by grab crane. Aftercrushing and sizing, it is transported to store yard or sent tocoke calcination plant.

Facilities are also provided in the plant to produce LPG andrelease fuel gases to fuel gas system.

Vacuum Residue

tank

Coker

FO tank

Coke

handling system

Amine treating

FG distribution

system

Unsat gas conc. unit

Heavy cycle gas oil Light cycle gas oil

To LNUU

To HNUU HP flare

LLP Flare

Unsat LPG

Merox unit

To LPG spheres

To flare

Coker consumption

To light slop oil tank

To heavy slop oil tank Lean amine amine

Rich

To ETP

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Advantages of Delayed Coker

u Minimum investment for given value addition

u Zero fuel oil generation

u Coke can be used as fuel for power plant.

u No catalyst cost.

u Capability to process refinery slops and sludge.

Mechanism of Coking

Cracking is a phenomenon by which large oil molecules arethermally decomposed into smaller lower-boiling molecules:at the same time some of these molecules, which are reactive,combine with one another to give even larger molecules thanthose in the original stock. The more stable molecules leavethe system as cracked Naphta, Kero, Diesel (LCGO), Gas oil(HCGO) etc. and the reactive once polymerise, formingcracked fuel oil and coke.

Fluidised Catalytic Cracking (FCC)

Fluid Catalytic Cracking has developed into a majorupgrading process in the oil refining industry for conversionof heavy fuel oil into more valuable products ranging fromlight olefins to LPG, naphtha and middle distillates. Theattractiveness of FCC process is to its flexibility to processwide range of feedstocks from a variety of crudes and itsfavourable economics of operation. The objective is tomaximise Olefins, LPG, C7 – C9 aromatics, high throughputand minimise LCO and bottoms.

Hot regenerated catalyst is mixed at the bottom of reactorwith raw feed and steam. After pre-acceleration, it is broughtin to contact with the staged feeds supplied as finelyatomised droplets. Feed instantaneously vaporises andtravels up the riser with the catalyst where conversionreaction takes place. At the top of reactor, the vapour isdisengaged from catalyst. The vapour is sent to mainfractionating column. In this column, mainly LPG, Gasoline,middle distillates and decanted oil are obtained. The spentcatalyst is steam stripped to remove hydrocarbon vapour andthen sent to two stage regenerators for burning coke beforeit is recycled to reactor alongwith makeup catalyst to reactor.

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Air is injected in catalyst regenerator for burning coke. Watergenerated in the system leaves with flue gas from PowerRecovery Train. Flue gases are sent to CO boiler andthereafter to a clean up system to remove particulates, SOxand NOx. ZSM additive is added to catalyst to increase LPGyield.

Residues are also used as feedstock in RFCC.

FIGURE 4.11 FCC UNIT BLOCK FLOW DIAGRAM

Petrochemical Process Plants

Aromatics Plant

The aromatics complex is a fully integrated facility forthe production of paraxylene and orthoxylene, comprisingof platformer primarily to produce feed for mainplants.

Aromatics complex processes special cut naptha to produceparaxylene and orthoxylene as the major products and someother by-products which include Benzene, Light Reformate,LPG, H2, Fuel Gas and heavies.

The Paraxylene plant consists of the following units. (Referfigure 4.12 Aromatics Complex Block Diagram Flow).

Heavy Naphtha Unionfining Unit (HNUU)

The function of this hydrotreating unit is to treat the feednaphtha and remove impurities like heavy metals, sulfur,

FCC

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nitrogen and olefins, which are poison for Platformercatalyst.

Platformer Unit

The platformer unit processes hydrotreated naphtha fromthe Heavy Naptha Unifining unit, stripper column bottoms,for the production of aromatics for downstream unitprocessing and separation. Major reactions taking place inplatforming unit are as follows:

1. Dehydrogenation of naphthenes

2. Hydrocracking of paraffins

3. Isomerisation

4. Dehydrocyclisation of paraffins

The spent catalyst is regenerated continuously in situ, whichtakes place in Cyclemax CCR.

Xylene Fractionation Unit

Xylene fractionation unit includes a xylene column andassociated equipments to fractionate “Isomar” Deheptaniserbottoms and “Tatoray” Toluene column bottoms into anoverhead product that is suitable as feedstock to the Parexprocess unit. The column is designed to both recoverOrthoxylene into the bottom product or to minimise the lossof Orthoxylene into the bottom products Xylene richoverhead vapor are used as heating medium in Raffinate &Extract . Column Reboilers & also to generate MP Steam.

Orthoxylene Fractionation Unit

This unit includes an orthoxylene column and associatedequipments for the production of a high purity orthoxyleneproduct and a heavy aromatic column and associatedequipments for the production of a C9-C1O aromaticoverhead stream to be used as feed to the “Tatoray unit”, asidecut stream with a 215°C endpoint for use as a gasolineblending component and a heavy aromatic bottom stream tobe used as fuel oil.

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Parex Process Unit

The process is selective adsorption of Paraxylene (PX)on molecular sieve and subsequent desorption of PX bya suitable desorbent. The molecular sieve is basicallyY type zeolite (alumina silica) which preferentiallyadsorbs PX.

Toulene column bottoms and C8 isomerates from Isomarsection are fed to the xylene fractionation column. Theoverhead product of the xylene columns are feed to the parexunit.

Feed and desorbent goes to the Parex adsorbent chambersvia rotary valve. PX gets adsorbed on the molecularsieve and subsequently desorbed. Two streams come outof the chambers known as raffinate stream and extractstream.

Raffinate stream is fed to the raffinate column. Its side cutproduct which is mixed xylenes lean in paraxylene, is fed toisomer unit while the bottom product desorbent is recycledback to Parex adsorbent chambers.

The extract stream consist of PX, Toluene and Desorbent.PX and Toluene are separated as overhead productsin extract column (feed to finishing column) while thebottom product Desorbent is recycled to Parex absorbentchambers.

PX and Toluene are separated in a finishing column.Paraxylene is withdrawn from bottom and overhead productToluene is recycled back to Tatoray unit.

Isomer is a catalytic isomerisation process to efficientlyconvert a mixture of C8 aromatics to a near equilibrium mixthat favours PX and OX production from metaxylene andethyl benzene.

The Tatoray unit includes reformer splitter column, twoparallel reactor trans, stripper, benzene are toluene column.Objective of the units is to maximise xylene production bytransalkylation of C7 and C9 aromatics.

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Polypropylene

It is designed to produce homo, random and impactcopolymer. The main raw materials are propylene andhydrogen. (Refer Figure 4.13 Propylene Block Flow Diagram)

The plant consists of:

1. Purification Section: For propylene “to removeimpurities like Sulphur, CO, CO2, O2' purificationsection for hydrogen and nitrogen gas before supplyingthem to reaction area. Impurities like CO, CO2 from H2

and O2 from N2 are removed.

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2. Reaction Section: Here polymerisation reaction ofpurified propylene takes place in fluidised bed reactorin the presence of slurry catalyst (TiC14, supported onMgCl2 in slurry form in mineral oil); co-catalyst TriethylAluminium, purified hydrogen and selectivity controlagent Peraethoxy Ethyl Benzoate or N-ProyplTrimethoxy Silane in the reactor.

3. Pelleting Section: Polypropylene (PP) resin istransferred from reactor to product receiver usingdense phase conveying system. The conveying gas whichis a mix of hydrocarbon and nitrogen is separated fromthe resin in disengaging section of product receiver. Theunreacted monomers are purged with light recycles andsent for recovery to vent recovery system. PP requiresthe incorporation of a variety of additives to aid itsprocessing and achieve the end use properties. Thepolymer is fed into the melt pump to develop necessarypressure for extrusion through the die plate. ThePolymer strands are palletised in underwater pelletiserand the pellets are carried by pellet water system toagglomerate remover where chunks and clusters areremoved. The pellets are then dried, classifiedand conveyed to the blending silos from where they arebagged.

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FIGURE 4.13 POLYPROPYLENE BLOCK FLOW DIAGRAM

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4. Vent Recovery Section: This system is designed torecover monomer, polymer and nitrogen. All wasteflammable gases are vented to the HP or LP flare header,which are passed through knockout pot and burnt atflare stack burning tip.

Typical Refinery and Petrochemicals complex � ProductPattern

Propylene 2.0%

LPG 7.0%

Gasoline 8.0%

Naphtha 8.5%

Reformate (Petrochemicals feed) 9.5%

HSD/SK/ATF 48.0%

Coke 8.0%

Sulphur 1.5%

Fuel and Loss 7.5%

Typical Refinery Product Pattern

Input % of Crude

Crude Oil 100.0

Products

LPG 2.1

Net Naphtha 5.0

MS 11.2

Others --

Light Distillates 18.3

ATF 2.6

SKO 9.0

HSD 35.1

LDO 16.0

Others 1.1

Middle Distillates 63.7

LSHS for sale 3.3

Others 7.9

Heavy Ends 11.6

Total Prods 93.6

Gross F&L 6.8

Total 100.0

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Typical Yield Pattern of FCC

Feed: 100%

Low ‘S’ VGO 53.7

CGO 20.3

DWO 9.0

VR 17.0

Output

Gas 3.9

H2S 0.5

LPG 12.7

Gasoline 12.5

TCO 53.4

CLO 8.6

Coke 7.9

Loss 0.5

Total 100.0

Typical Yield Pattern of Delayed Coking Unit

Input = RCO 100%

Output:

LPG 2.5

Cok. Gasoline 4.5

Cok. Kero-I (LK) 22.5

Cok. Kero-II (HK) --

Cok. Gas Oil (CGO) 24.5

CFO 14.5

RFO 6.5

RPC 16.3

GAS 6.3

Loss 2.4

Total 100.0

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Typical Yield Pattern of Hydro-treater

Input:

VGO 100.0

H2 2.0

Total 102.0

Output

H2S 1.2

GAS 1.3

LPG 3.0

LT. Naphtha 11.5

Hy. Naphtha 4.0

SKO/ATF 27.0

HSD 43.8

Bottoms 10.0

Loss 0.2

Total 102.0

Offsite Facilities and its Management

In a Refinery, 80% to 90% area is covered by offsite facilities.Traditionally, more attention used to be given to processunits. However, with Refinery margin shrinking, stringentsafety, Health and Environmental stipulations, andincreased customer expectations, now more and moreemphasis is given for improved profitability through:

l Improved operations

l Advanced process control system

l Good inventory management

l Optimisation of storage facilities & other offsites.

Major offsite functions in a Refinery are:

1. Crude oil receipt

Normally crude oil is received in land locked refineriesthrough crude pipelines from the production source. Beforebringing the crude from oil fields, gas, water and sludge areremoved by settling and processing through desalters. In

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coastal refineries, crude oil is received through tankers.Depending on the capacity of the refinery, crude tankageavailable, draft available at receiving oil jetty, size of crudeoil tanker varies from small to very large. Quantity of crudereceived in the refinery is monitored by measuring dip ofreceiving tank and flow metre readings installed on crudepipeline. India imports almost 70% of its crude oilrequirement. Due to strategic reasons, crude oil storage isbeing increased from 15 days to 45 days of the refinerycapacity.

2. Crude preparation for feeding to distillation units

Though in the oil field, major quantity of sludge, water andassociated salts are removed before bringing crude torefineries, yet some quantities of sludge and water still arereceived in the refinery tanks. This is removed by allowingthe crude to settle in the tanks and draining from bottom tothe effluent treatment system. The final removal of waterassociated with salts and sludge takes place in desalter inthe crude distillation unit. Unless crude preparation is doneproperly, the unit performance will be affected adverselydue to fouling of pipes, exchangers, furnace tube corrosion,corrosion of various equipments and upsets in plantoperation. This will also lead to increased fuel consumptionand loss in the units.

3. Receiving rundown streams from various units

From crude distillation unit and other secondary units, weget various products streams, most of which are to be treatedin secondary processing units and blended in requiredproportion to produce finished products which are thendispatched to the market. Except LPG and Naptha, all otherproducts are blends of various streams from different units.Depending on the capacity of refinery, number of productsmarketed, types of crude oil processed, complexity of therefinery, the tankages provided for receipt of rundownstreams varies. Facilities for water draining andreprocessing of offspec. streams are provided. Flexibility isalso provided for alternative routing of streams incase thereis change in demand in product pattern. Light and heavy

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slop tanks are also provided to receive offspec. Streamsduring start up, shutdown, emergencies and upsets in theplants. The same are reprocessed in the units in a regulatedmanner during normal run. By on-line blending and utilisingadvanced process control, the tankage for receiving rundownstreams can be minimised. Pump stations are provided fortransfer of products.

4. Blending the rundown streams

Various straight run streams and secondary processing unitsstreams are mixed in suitable proportion for the productionof finished marketable petroleum products. The mixture iscirculated in the tank to make it of uniform quality. Aftersettling in tank for draining any water and testing the samplein the laboratory to ensure that it meets qualityspecifications, it is dispatched to market. Storage facility atvarious locations particularly for MS, SKO and HSD is beingaugmented. It is proposed to provide 35 days storagecapacity based on 75% utilisation factor.

5. Co-ordination with laboratory

After blending of various streams and circulation in tank,samples of products are sent to the laboratory for testing.Once the product meets the quality specification as per BISor customers requirement, then the certificate of quality isissued by the laboratory. Thereafter, product is despatchedto market.

6. Despatch of finished products:

The certified products are stored in finished product tanksbefore dispatch.

Petroleum products are evacuated from the refinery byfollowing modes:

1. Pipelines

2. Rail

3. Road

4. Coastal

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1. Pipelines: Out of the above dispatch modes ofpetroleum products, maximum dispatch takes placethrough pipelines (60 - 70%). Pipeline systems havefollowing in-built advantages over other means oftransportation available for petroleum products:

1. It is the second cheapest mode of transport next tolarge capacity tankers.

2. With advanced control system and properoperation, it is possible that the products reachtheir destination in a "refinery-good" condition.This is so even in respect of sensitive quality controlproducts such as ATF, Naptha etc.

3. Minimum transit loss

4. Planned product movement

5. Flexibility in operation independent of othertransportation systems. During floods and naturalcalamities, it is not affected.

2. Rail: Tank wagons are the second bulk carrier speciallyconstructed for this purpose and can take products tofar off places. The wagons for transporting heavyproducts such as FO, LSHS etc, are provided with steamcoils for heating the product before unloading at thedestination.

3. Road: The third mode of transportation is tank lorriesor tank trucks, which are used to supply product tonearby locations by road. Steam coils are provided toheat the product before unloading in case of tank trucksfor Bitumen, LSHS, FO, etc.

4. Coastal: Tankers of various capacities are used fordispatch of product from coastal refineries. For shortdistance and small quantity of coastal productmovement, barges are used. The large capacity tankersare the cheapest mode of transport.

The products movement of the refinery gets adverselyaffected due to failure/breakdown of transport system.

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Flexibility to a small extent exists to switch over fromone mode to other mode. However, refinery builds upstock in its tanks during such emergencies, to an extentbeyond which through-put of process units is cut thusaffecting the production.

7. Flare management

To take care of emergency release of gaseous hydrocarbon,flare headers are provided for collecting off gases fromprocess units and offsite areas. After seperating theentrained liquid, the gas is burnt at high point to avoidhazard and pollution. Three categories of flare systems areprovided:

a. High pressure flare

b. Low pressure flare

c. H2S flare

8. Refinery water supply

The following important water supply systems exist in therefinery.

1. Fresh water supply system: This provides utilitywater supply, make up to the circulating water system,make-up to fire water supply system and make up todrinking water treatment system.

2. Fire water supply system: Throughout the processunits and offsites areas, the fire water supply pipelinenetwork is laid in the form of ring. Firewater tanks areprovided in offsites area to have an immediate supplysource for fighting any major fire. In critical areas, longdistance throw nozzles are provided.

3. Recirculating hot and cold water system: For coolingof hot products, this system is provided. It is havingchemical treatment system to avoid scaling andcorrosion in related pipelines and equipment. CoolingTowers are also provided in the system where water iscooled by evaporation before recirculation. Blow-down

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in the form of leakage and manual draining is providedto avoid build up of salt concentration. Make up wateris taken from fresh water system. In some of the coastalrefineries, once through cooling water system is usedand sea water is utilised for the cooling of products.

4. Captive power plant: To provide uninterrupted powerand steam supply for running the pumps, compressorsand other equipment, captive power plant is providedin the refinery. For meeting any emergency, alternativesource of power supply from outside is also lined up.Superheated and saturated steam at various pressuresare also supplied for process units and offsites area fromthis system. Steam is used for heating, stripping incolumns, atomisation of fuel oil before burning infurnace, fire-fighting, driving steam turbines and powergeneration. Fresh water is used in DM plant beforeutilising in boilers for steam generation. To ensuresupply of steam and power to critical plants/equipmentin emergencies, load shedding scheme exists.

5. Fuel oil and fuel gas system: For providing fuel supplyto process units furnaces, and boilers in captive powerplant, this system is provided. In fuel gas, mostlymethane, ethane and purged gases from hydrogen unitsare used. The supply system is maintained at constantpressure. For fuel oil, varying range of fuels from LDOto Asphalts are used. Storage tanks, blending facilitiesand pumping system are provided for supply of fuel oilto furnaces and boilers.

6. Hydrogen, Nitrogen and air supply systems:Hydrogen is generated in Hydrogen plant or catalyticreformer unit. It is utilised in hydro-treatment units. Itis a very hazardous gas to handle as the flame can notbe seen.

Nitrogen is used for catalyst regeneration, blanketingtanks from atmospheric oxygen in the case of lubes andother products which form explosive mixture whencoming in contact with air, and maintaining inertatmosphere in the process unit equipment. Nitrogen is

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produced in generators installed in the refinery or ispurchased from outside. Air is used for utility purposes,catalyst regeneration, decoking of furnace tubes andinstrumentation etc. It is taken from atmosphere andcompressed before using.

Review Questions for Offsites

1. What are the important offsite facilities in a refinery?

2. How do these facilities affect the proper functioning ofthe refinery? Explain each facility wise, specially theirimpact whenever there is a failure.

Review Questions for all Process Plants

1. Explain briefly in your own works.

i. The function of each process plant (11 plants)

ii. Feed composition

iii. Yield pattern.

iv. Critical parameters for optimal operation

2. Which components of various process streams indifferent process plants (% wise) are utilized for theprouction of LPG, MS, HSD, ATF, Furnace Oil, PCNaphtha and Fertilizer Naphtha.

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Unit 5

Future Refining Scenario

Keeping in view environmental considerations, costoptimisation, energy conservation and product qualityrequirement, it is envisaged that future refineries will haveto face many challenges – they will be highly complex,integrated, diversified and fully automated.

Worldwide availability of sweet and light crude isdecreasing, therefore, future refineries will have to be readyto process heavy and sour crudes. This will call for superiormetallurgy in the plants and pre and post treatment of oilproducts leading to higher capital and operating costs. Toimprove profitability and meet statutory requirements,following actions need to be taken:

u Distillates yield improvement

u Production of high value products

u Energy optimisation

u Hydrocarbon loss minimisation

u Effective environmental management

u Product quality upgradation

u Product inventory reduction

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y Understand Future Refining Scenario in terms of availability ofcrudes, stringent specifications of various petroleum products,dwindling refinery margins etc.

y Strategies for overcoming various challenges.

Activity 5 A

Describe the scenario ofavailability of sweet & sour crudesin the next two decades.

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Besides conventional process units, future refineries will alsohave:

u Quality related units:

– Facilities for benzene management

– DHDS (Diesel Hydro-desulphurisation)

– Fuel oil HDS (Hydro-desulphurisation)

– Hydrotreatment.

u Environment management related units:

– Tail gas treatment

– High efficiency SRUs (Sulphur Recovery Units)

– Bottom of the barrel upgradation related unit

– Computerised integrated refinery

– Energy efficient processes

– Diversified and integrated refinery with powerplant, petrochemicals and fertilizers

u Synergy in power with fertilizer co-production

– Efficient utilisation of low value refinery residuefor production of power. Power plant suppliespower and steam required in refinery.

– Co-production of value added fertilizer.

– No additional raw material handling and commonfire fighting facilities.

– Overall economics considerably enhanced

– Already under way in the USA, the Netherlandsand Italy.

u Refinery of 21st century

– Operate with fewer & highly educated people

– Few operators grouped in a central blast proofcontrol room like the cockpit of modern aeroplanes.

Activity 5 B

What do you understand fromIntegration of Refinery with petro-chemicals/ fertilizers, powerplants? How does it improve theBottom Lines?

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– Possible employment of robots

– Computerised system supervising operationsautomatically

– On-line analysers and blending

– Computerised performance monitoring

– Automated dispatch and offsites operations

– Flexible work hours

In the new refineries, following technology gaps and to becovered:

u Reduction of ‘S’ (sulphur) from MS, HSD and FO.

u Reduction of FO production and increase in distillateproduction to 85%+.

u Plant/ equipment should require less space.

Review Questions

1. What modifications would be needed in refinery processplants for

- Changing over from sweet crude to sour crude

- Technological improvements/additions for meetingfuture more stringent specifications of HSD andMS. So as to conform to Emission norms.

- To increase/improve profitability.

2. What do you understand from flexibility of Refineryoperations in the competitive environment?

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Unit 6

Advances in PetroleumRefining

Various issues faced by the refining industry have led tomany major developments in this area. The challenges are:

1. Crude oil is becoming heavier and higher in sulphur andmetal content.

2. Reduced growth in fuel oil demand.

3. Rapid growth in light/middle distillates.

4. Stringent environmental regulation for cleanerproducts/processes and demand for quality products.

5. Declining refining margins

6. Improved engine design/automobiles need better qualityfuel and lubricating oils.

Advances in refining technology can be broadly divided intothe following categories.

1. Improved and integrated refining

u Production of better quality products

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y Understand in a generic fashion advances in refining processtechnologies

- For making eco-friendly products

- For value addition to improve the bottomline

- For best practices in refining operations

- For energy optimization

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u Residuation in residues/heavier ends

u Management of power and utilities.

2. Value addition

u Petrochemicals production

u Better quality and increased lube oil production

u Power generation from heavier petroleum products

u Speciality chemicals production.

Improvements are taking place in many areas. Some of themare listed below:

u Distillation

u Fluid Catalytic Cracking (FCC), Resid Fluid Catalyticcracking (RFCC).

u Delayed coking – Needle coke manufacturing,Visbreaker–Soaker Technology.

u Hydro processing

– Hydro treatment of various streams includingresidues.

– Hydro cracking

u Super Oil Cracking (SOC) of heavy distillates to get 90%conversion to distillates.

u Mobil distillate Dewaxing (MDDW) to upgradeheavy fuel oil to high quality distillate and gas yield of93- 95%.

u Isomerisation

u Catalytic Reforming

u Alkylation

u Etherification

u Power generation by petroleum residue and coke byusing Gasification Combined Cycle (GCC) technology.

Activity 6 A

What are known/provenimprovements as on date, inRefining Process Technologies?

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In this process alongwith power, steam and H2 can beproduced which are required in the refinery.

u More and more use of information technology.

u Modelling simulation are being used for:

– Information Gathering, Decision Making andBusiness Profitability.

– Accurate process models for different processes(e.g., FCC, Hydrocracking, Cat Reforming, etc) arebeing developed and increasingly used foroptimization, trouble shooting, design and optimalcontrol and technology development.

– Typical application of information technology in arefinery

u Significance of process modelling

u Refinery integration and value addition strategies

u Small and medium refineries

Guide logistic

planning Refinery planning

Primary logistic

management

Refinery scheduling

Primary logistic

management

Secondary logistic

management

Reactor design

Trouble shooting

Modelling and

simulation

Pilot plant scale up

Catalyst health

monitoring Catalyst

selection & optimisation

Operator training Process

optimisation Feedstock selection

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– Integration with speciality chemicals for valueaddition

– Anode grade coke, needle coke production

– Microcrystalline wax production

– Alpha-olefins production

u Larger refineries

– Petrochemical integration and speciality products

– Integration of refining and power generation –IGCC Technology

– Lubes and fuel integration

u Other major strategies of integration

– Integration with IT

– Process simulation and optimisation

– Advanced control and hierarchical control systems

Review Questions

1. Explain the following processes and relate the same tothe relevant products:

- Isomerization

- Alkylation

- Etherification

- DHDS

- Catalytic reforming

- Catalytic cracking

- Thermal cracking (Refer Bibliography)

2. Explain the known/proven processes of HydrogenGeneration from heavy residues/petroleum coke/ coalbed methane?

3. How is IT utilised for improved/on-line performancemonitoring of refineries?

Activity 6 B

What are various routes for valueaddition in Petroleum Refining?

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Unit 7

Hydrocarbon LossMinimisation

During the processing of crude petroleum products, handlingand dispatches from refinery, hydrocarbon losses take placeon various accounts. Efforts are to be made to bring the lossto a level of less than 0.3% of crude processed. Auditing ofthe systems and operations will lead to continuousimprovement.

Following areas need to be monitored/looked into:

A. Apparent losses

i. Measuring devices in storage tanks and custodytransfers for proper accounting

ii. Automating road/rail dispatch facilities.

B. Real losses

i. Vapour recovery from flare and product loadingfacilities

ii. Handling of light hydrocarbon slop in process unitand offsite area in closed blow down system

iii. Conversion of fixed roof tanks to floating roof tanksfor low flash products including diesel and use ofproper type of roof seals.

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y Understand the significance of losses in a refinery and their impacton profitability

y Understand sources/areas of losses and measures adopted by

the refineries for their reduction.

Activity 7 A

i. What should be ideal lossesin any Process Control?

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iv. Automatic tank gauging

v. Use of proper mixers in crude tanks for minimisingsludge formation and modern method of removaland recovery of only sludge/oil to reduce loss

vi. Minimising slop generation to reduce evaporationloss in slop handling system

vii. Close monitoring of BSW in crude processed toavoid plant upsets and increased losses.

viii. Routing of all sour gases to sulphur recovery unit

ix. Routing of off gases from vacuum column tofurnaces.

Review Questions

1. What will be the order of magnitude of savings in a sixmillion tones per year capacity refinery, if the lossesare reduced by 0.2%, cost of crude being $ 25/barrel?

Activity 7 B

i. What are internationalstandards for RefineryLosses? What methods havebeen adopted in Indianrefineries to bring down thelosses to Internationalstandard?

ii. What is BS&W? How is itrelated with losses in Refiningoperations?

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Unit 8

Energy Conservation

Conservation of oil and gas has assumed greater importancein view of the emphasis on demand side management ofenergy. Average fuel loss in the refineries in India during2000–01 was 7-35% which is higher compared to global levels(of similar configuration).

Energy optimisation for a refinery begins early in thedevelopment and design stage with the establishment of aset of energy saving guidelines applicable to the project. Someof the areas given below need to be looked into:

1. Integration of heat – exchange system of the units toutilize the heat from hot stream of another unit – crudedistillation unit and vacuum distillation units are heatintegrated.

2. Optimisation of heat exchangers train – use of pinchtechnology.

3. Direct hot feed from one unit to another unit withoutpassing through intermediate tanks.

4. Energy efficient processes/equipment such as furnaces,pumps, exchangers etc. Provision of air preheter infurnace.

5. Proper insulation of hot products and steam lines.

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Objectives


y Appreciate the role of/ urgency for energy conservation andoptimisation of energy consumption in refining industry.

y Get a generic idea of various strategies adopted for energyoptimisation.

Activity 8 A

i. What strategies have beenadopted to optimize energyconsumption.

- For old refineries

- For grass-root refineries

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6. Optimisation of

i. Reflux ratio in distillation process

ii. Solvent feed ratio in extraction process

7. Use of soaker technology for visbreaking.

8. Use of microprocessor based control system alongwithDDCS (Digital Distributed Control System) andadvanced process control.

9. Heat recovery from process streams for heating colderprocess streams/ boiler feed water.

10. Power generation in new refinery will be throughcombined cycle operation integrated with gasification.

11. Steam system – High pressure steam will be cascadeddown to lower level by back pressure turbines eithergenerating power or coupled with various key processcompressors and pumps. Pressure reduction of steamthrough a control valve will be minimised.

12. Minimise leakage through glands/seals of pumps,compressors and turbines.

13. Low level heat recovery.

14. Soot blowers for convection section of furnaces toimprove heat recovery in furnaces.

15. Steam generation from hot streams.

16. Benchmarking, gap analysis and setting targets.

17. Energy audit for continuous improvement of energyperformance.

Review Questions

1. How does energy consumption at Indian refineriescompare with best run refineries over-seas? Expressthis in energy consumption indices like

- EII (Energy Intensity Index)

- NRG Factor in MBTU's per NRGF for fuel + loss

Activity 8 B

How do DDCS and advancedprocess controls help conserveenergy?

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2. Explain the role of house-keeping measures for bringingdown energy consumption resulting in energyconservation. Enumerate some important measures ofthis nature which the refineries/ chemical industriestake.

Notes

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Unit 9

Gross Refining Margin

Gross Refining Margin (GRM) is the differential betweenthe product realisation and the cost of crude processed toobtain these products. GRM of a particular refinery willdepend upon various internal and external factors. Some ofthese factors are discussed below:

Internal Factors

u The crude mix (low sulphur and high sulphur) processedby the refinery

u The secondary processing facilities available with therefinery which affect the product yield of the refinery

u The fuel used and losses incurred in the productionprocesses.

External Factors

u The international prices of various crudes and products

u The demand and supply balance of various productsrefined by the refinery

u The duty structure prevailing in the country relating tocrude and products.

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Objectives


y Provide an appreciation for various elements affecting GRM whichin essence is the profitability of a refinery.

y Acquaint with the netback estimation method used for selection

of crude for any refinery.

Notes

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Operating Cost of the Refinery

The operating cost of the refinery includes various elements,some of which are as under:

u Power and fuel: Fuel is used either directly in therefining process or to generate power and utilities to beused in the refining process. Fuel may be purchased fromoutside suppliers (like natural gas), power fromelectricity board or internal refined products (likeLSHS, FO or HSD) may be used as fuel.

u Chemicals and catalysts: During the refining processof petroleum products, various chemicals and catalystsare used. The purpose of chemicals is mainly to improvethe quality of products so as to meet the desiredspecifications. Catalysts are used in various reformersand other secondary processing facilities.

u Establishment cost: This is related to the manpowerdeployed and includes the salary and wages paid to staff,overtime, bonus etc.

u Repair and maintenance cost: It is incurred in variousmechanical, electrical and civil jobs carried out for themaintenance of plant and machinery.

u General administrative cost: This cost includesexpenses such as traveling. Printing, insurance andother related overhead expenditure.

u Depreciation: Operating cost includes depreciation onplant and machinery, furniture, equipment and otherfixed assets used in the refining process towards generalwear and tear.

Net Margin

The net margin is the difference between gross margin andoperating cost. This is virtually the net profit to the refinery.

Net Margin = Gross margin – Operating cost.

Activity 9 A

What are various factors whichaffect GRM?

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For higher profitability, gross margin should be increasedand operating cost reduced by increased efficiency in refiningoperations. Attachment 1 shows a sample calculation forgross and net margin for a refinery.

ATTACHMENT 1: GROSS MARGIN

Rs/Crores

Realisation of transfer of products 4050

Cost of crude (inclusive of freight, wharfage, customs duty) 3720

Gross margin 330

Th’put-MMT 3.98

GROSS margin Rs/MT 829

Margin – Rs/BBL 112

Margin – US $/BBL US $ 2.30

Less: Operating cost Rs/MT 500

Net margin Rs/MT 329

Net back estimation

In the net back system, the estimated realisation iscalculated on the basis of expected yield from the particularrefinery for a specific crude. For the purpose of procurementof crude for a particular refinery, net back estimation is usedto evaluate the suitable crude for the refinery. The crudewhich is having higher net back to the refinery is normallyprocured for it.

Attachment 2 gives a sample netback calculation to selectthe best crude out any of seven crudes, considered. All these7 crudes are sweet (low sulphur) crudes. F.Dos gives thehighest netback of Rs 1054/MT vs TAPIS with lowest netbackof Rs 41/MT.

Activity 9 B

Explain how netback estimationmethod is used for crude selectionfor a refinery?

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PROD PRICE

BRENT BL

F.DOS BON. LT. LABUAN ESCRAVOS TAPIS MIRI

CRUDE PRICE

RS/MT 11987 11361 11714 11994 11987 12859 11994

LPG 14599 7 5 5 4 2 5 4

NAP 12260 8 0 5 2 5 10 3

MS 14832 12 12 12 12 13 12 12

SKO 13617 11 11 11 11 11 11 11

HSD 14361 48 58 54 58 51 53 59

OF 10100 0 0 0 0 0

L.SHS 10100 1 0 0 0 6 0 0

RPC 5535 2 1 1 2 6 1 1

SULPHUR 256 1 1 1 1 0 1

SL. WAX 13851 0 0 0 0 0 0 0

F & L 0 10 12 11 10 6 8 9

TOTAL 100 100 100 100 100 100 100

DIST% 86.0 86.0 87.0 87.0 82.0 91.0 89.0

CRUDE VALUE,RS/MT

11987 11361 11714 11994 11987 12859 11994

PROD VALUE, RS/MT

12408 12415 12454 12570 12593 12900 12780

LESS IPN COST, RS/MT

100 100

NET BACK, RS/MT

421 1054 740 476 606 41 686

ATTACHMENT 2: SAMPLE WORKING OF NETBACK CALCULATIONS

Review Questions

1. What are the most crucial factors and which are indeedcontrollable, affecting GRM?

2. What are various options for reducing Refining Costsin competitive world?

Notes

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Unit 10

Oil Accounting

While the physical handling of crude oil, intermediates andfinished petroleum products is done by operations personnel,the Oil Accounting Section of the finance department of arefinery/warehouse is responsible for correct depiction ofthe quantitative and financial records pertaining to the crudeoil and petroleum products.

Quantitative accountal and correct payment of duties onfinished petroleum products is the focal area of the oilaccounting section. The following are its key functions.

1. Accounting of Crude Oil Receipts and DutyImplications Thereon

Crude oil received under bond from port locations and re-warehoused in a refinery needs to be accounted on FIFObasis and appropriate customs duty is required to be paidand accounted for the quantity taken in the process ofrefining. This is known as ex-bonding of crude.

2. Accounting of Manufactured Petroleum products andThose Received for Blending, etc.

The duty liability on petroleum products arises when theprocess of manufacture is completed, although the dischargeof duty obligation is allowed to be deferred to the time ofremoval from the refinery/onward removal to warehouse.Hence, tank accountal of receipts and removals is to be

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Objectives


y Provide a general idea of accounting methods for crude andpetroleum products and its significance.

Notes

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maintained by taking dip measurements and quality testingreports.

3. Despatch of Finished Petroleum Products

Assessment to central excise duties is invoice-based. Whetherthe goods removed are duty-paid or under bond, the exciseduty liability is determined at the time of removal from therefinery warehouse. With the invoice being the document insupport of cenvat credit claim that may accrue to a customer,the invoice/application for duty-free removal is thecornerstone for correct excise assessment of removals.

4. Compliance of Excise Procedure and Maintenance ofRecords

The excise department tests compliance of law and procedureprimarily through the records maintained by the oil accountssection of the assessee. For duty-paid goods, the liabilitylikely to arise during a working day is to be deposited inadvance through treasury challan at the bank and the depositcredit is to be utilised in accordance with the invoices issuedfor the clearances. This is done through the PLA (PersonalLedger Account). The DSA (Daily Stock Account) is to bemaintained for opening balances, production, dispatch andclosing balances of all certified finished products of therefinery warehouse. Intimations/declarations are to besubmitted to the range office for any act or action that maybe regarded as having an impact on revenue.

5. Material Balancing, Production Statistics andPeriodical returns and Statements

As the crude oil is processed through a combination ofdistillation and blending, intermediary products arise duringthe course of manufacture of certified finished petroleumproducts. The control over inputs and outputs during thisrefining process is achieved through the daily materialbalancing done through the quantitative measurement oftank and line-fill quantities of the crude, intermediaries andfinished products. The production statistics are correlatedto the standard product pattern and the actual distillate yieldfor any particular period of time.

Notes

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Statutory returns as per excise procedure are filedperiodically by the oil accounts section with the range office.Records, returns, documents, etc prepared by the oilaccounting section are open to inspection by the range office.Letters, show cause notices, if any, are normally issuedthrough the oil accounts section.

Review Questions

1. Method and system of accounting crude and petroleumproducts in a refinery?

2. How is the excise/customs procedure followed by oilaccounting section?

Notes

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Unit 11

Excise and Custom � PetroleumProducts

The removal of petroleum products manufactured inrefineries is either to direct customers or through marketingnetwork (warehouses/ depots/terminals, etc) for saletherefrom. Products belonging to oil marketing companiesare also dealt through intercompany transactions.

These products are either removed on payment of exciseduty, or under bond without payment of excise duty. In thelatter case, the duty obligation on the manufactured goodsis discharged from the warehouse when it is finally clearedfor sale. In certain cases, the goods are removed under bondto special industrial undertakings like SEBs, FCI, etc whoare licensed to deal with manufactured excisable goodswithout payment of duty.

The products are removed through pipelines, tank wagon(railways), tank lorries (oil tankers), or barges (throughwaterways).

The primary raw material for finished petroleum productsis crude oil, indigenous and imported. Indigenous crude oilattracts Nil rate of excise duty, whereas imported crude oilattracts 10% customs duty. Indigenous crude oil is sourcedfrom Gujarat and Assam oilfields and from offshore oilfieldsof India. Imported crude of different varieties as per

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y Give an overview of excise and customs procedures/formalitiesas applicable.

y Provide an appreciation for the manner in which custom and exciseduties affect profitability.

Activity 11 A

What is the present level of customand excise duties on crude andvarious petroleum products? Whatis the rationale for fixing the same?

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processing requirement are brought through different portsof the country.

While crude oil only attracts the basic customs duty, otheritems of import attract additional duty of customs (equivalentto the excise duty attracted for such items under the centralexcise tariff) and special additional duty of customs onselective basis as notified. The additional duty of customslevied under the Customs Tariff Act and the excise dutylevied under the Central Excise Tariff Act are allowed to beset-off as duty credit by the refineries (manufacturer) underthe Cenvat Credit Scheme of central excise. During dischargeof excise duty obligations arising on the removal of finishedpetroleum products from the refineries on duty-paid basis,the refineries use the accumulated cenvat credit in lieu ofcash payment.

Other than basic excise duty, there is a levy, on selectivebasis by notification, of special excise duty, additional dutyof excise (Re. 1 per litre on Motor Spirit commonly known aspetrol and on high speed diesel oil commonly known asdiesel), and recently introduced special additional duty ofexcise on MS.

Petroleum products are handled under the Self-Assessment Scheme of Self Removal Procedure (SRP) ofcentral excise. The excise assessee is required to takenecessary actions to be within the legal and proceduralrequirement of excise and customs law, without physicalsupervision of the department. At the refinery/warehouse,the department is represented by the jurisdictional officer-in-charge (superintendent) of the Excise Range Office whohas been given power of unified customs and central excisecontrol over imported crude oil and excisable finishedproducts of the refinery.

Review Questions

1. In the event of excess refining capacity (with glut in themarket), what level(s) of production should be maintainedto meet domestic demand and export the product?

2. What is the significance of bonded warehouse? How arecrude and products removed and accountal done?

Activity 11 B

When is it desirable to export/import any product based oncustom/excise duties prevailing?

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Bibliography

1. Advanced Petroleum Refining, Dr. G.N. Sarkar, KhannaPublishers, Delhi

2. Reading Material of Programme on Petroleum Refiningand Petrochemical Technology, Indian Institute ofPetroleum, Dehradun.

3. Reading materials of programme on Refining &Petrochemicals of various Petroleum Companies.

4. Petroleum Refining Engineering, W.L. Nelson, Mc.GrawHill.

5. Handbook of Petroleum Refining Process, Robert A.Meyers

6. A layman's Introduction to Oil Refining - D.G. Crook

7. "Managing Modern Offsite Operation" by Patrick B.Truesdale and J. Dauglas AMOS

8. Course contents on Refinery Loss Control by Dr. EricRobinson and Dr. John Miles at Singapore, 20-21st May,1996.

References

1. Advanced Petroleum Refining, Dr. G.N. Sarkar, Khanna Publishers,Delhi

2. Petroleum Refining Engineering, W.L. Nelson, McGraw Hill

3. Modern Petroleum Refining Processes, Dr. B.K. Bhaskar Rao, IIT,Kharagpur

4. Advances in Petroleum Chemistry and Refining - Kennetha A. Kobe,John J. Moketta

5. The Chemistry and Technology of Petroleum (Mercel Dekkar), SpeightJ.G.

6. Petroleum Monthly Publication, Malaysia

7. Hydrocarbon Processing

8. New Challenges, Technologies Options for Refineries - IOC, R&D ReportNo. 96018, March, 1996

9. KBC Petrofine Users Manual

10. A Layman's Introduction to Oil Refining - D.G. Crook

11. Refinery Loss Controls - Course Manual Presented by Dr. Eric Robinsonand Dr. John Miles on 20-21 May 1996 at Singapore.

Notes

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Documents

Fundamentals of Refining