INDUSTRIAL TRAINING AT

Indian Oil Corp. Ltd., Mathura A PROJECT REPORT

SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE

BACHELOR IN TECHNOLOGYBACHELOR IN TECHNOLOGYBACHELOR IN TECHNOLOGYBACHELOR IN TECHNOLOGY ININININ

MECHANICAL ENGINEERINGMECHANICAL ENGINEERINGMECHANICAL ENGINEERINGMECHANICAL ENGINEERING

Under the supervision of

Mr. Y.G. SHROFF

(Chief Maintenance Manager)

Submitted By

SALIL SAGAR

DEPARTMENT OF MECHANICAL ENGINEERING

ZAKIR HUSAIN COLLEGE OF ENGG. & TECH.

ALIGARH MUSLIM UNIVERSITY (A.M.U.)

ALIGARH (U.P.)

2010-11

PREFACE

Industrial training plays a vital role in the progress of future engineers. Not

only does it provide insights about the industry concerned, it also bridges the

gap between theory and practical knowledge. I was fortunate that I was

provided with an opportunity of undergoing Industrial training at INDIAN OIL

CORPORATION Ltd., Mathura, one of the leading refineries in India. The

experience gained during this short period was fascinating to say the least. It

was a tremendous feeling to observe the operation of different equipments

and processes. It was overwhelming for us to notice how such a big refinery is

being monitored and operated with proper co-ordination to obtain desired

results. During my training I realized that in order to be a successful

mechanical engineer one needs to possess a sound theoretical base along

with the acumen for effective practical application of the theory. Thus, I hope

that this industrial training serves as a stepping-stone for the students and

helps to be successful in future.

ACKNOWLEDGEMENT

My indebtedness and gratitude to the many individuals who have helped to

shape this report in its present form cannot be adequately conveyed in just a

few sentences. Yet I must record my immense gratitude to the brains and

hands that worked overtime to support my efforts in making a near

comprehensive report on the vocational training in Indian oil corporation Ltd.,

Mathura.

I am highly obliged to Mr. Y.G. Shroff, Chief Maintenance Manager for

giving me this opportunity to work under his supervision and lending me his

learnings over the month and continuous guidance in his capacity as my

Project Guide. The thank list would be far from incomplete without the

mention of all such supervisors, associates and all the employees of IOCL,

Mathura.

Last but not the least I am thankful to Almighty God, my parents, my uncle,

my friends for their immense support and cooperation throughout. In fact the

list can never be completed….

SALIL SAGAR

ABSTRACT

Indian Oil Corporation Limited, or Indian Oil, is an Indian state-

owned oil and gas company headquartered at Mumbai, India. It is India’s

largest commercial enterprise, ranking 125th on the Fortune Global 500 list in

2010. IndianOil and its subsidiaries account for a 47% share in the petroleum

products market, 34.8% share in refining capacity and 67% downstream

sector pipelines capacity in India. The Indian Oil Group of Companies owns

and operates 10 of India's 19 refineries with a combined refining capacity of

65.7 million metric tons per year.

IndianOil operates the largest and the widest network of fuel stations in the

country, numbering about 17606 (15557 regular ROs & 2049 Kissan Sewa

Kendra). It has also started Auto LPG Dispensing Stations (ALDS). It

supplies Indane cooking gas to over 47.5 million households through a

network of 4,990 Indian distributors. In addition, IndianOil's Research and

Development Center (R&D) at Faridabad supports, develops and provides the

necessary technology solutions to the operating divisions of the corporation

and its customers within the country and abroad. Subsequently, IndianOil

Technologies Limited - a wholly owned subsidiary, was set up in 2003, with a

vision to market the technologies developed at IndianOil's Research and

Development Center. It has been modeled on the R&D marketing arms

of Royal Dutch Shell and British Petroleum. It owns and operates the

country’s largest network of cross-country crude and product pipelines, with a

combined length of 7,730 km with a combined capacity of 56.85 MMTPA.

Mathura Refinery was commissioned in the year 1982. At present it has the

capacity of processing 8.0 MMTPA of crude oil. The refinery meets the

demand of Northwest region of India including Delhi. The crude oil with low

sulphur from Bombay High, imported crude with low sulphur from Nigeria, and

crude with high sulphur from Middle East Countries are processed at this

refinery.

The original refinery configuration had one primary Atmospheric Vacuum unit

and the secondary units were the Vis-breaker Unit, Bitumen Unit, Sulphur

Recovery unit and Fluidized Catalytic cracking Unit.

Gradually Mathura Refinery in Uttar Pradesh made certain changes to follow

the strict product specification that aroused due to environmental

considerations. The secondary units such as Once Through Hydro-cracker

unit (OHCU).

Catalytic Reforming Unit (CRU), MS quality up gradation, Diesel hydro de-

sulphurisation Unit, (DHDS), new Sulphur Recovery unit (SRU), DHDT etc

were integrated in the refinery configuration. These changes in the

configuration of the Refinery were made so that there is minimal impact on the

environment.

Mathura Refinery has taken a number of initiatives to save the environment,

public health and also to preserve the national monuments in and around the

city of Mathura. A lot of research has been done to produce more and more

clean fuels that would have minimal negative effect on the environment.

Mathura refinery has been producing highly eco-friendly petrol and diesel for

the NCT, NCR and Agra region. The Refinery enjoys the distinction of being

the first refinery in India capable of producing 100% auto fuels that meets

Euro - III norms.

Products from this refinery are dispatched through rail, road and Mathura-

Delhi – Ambala - Jalandhar pipeline. The LPG bottling plant situated within

Mathura refinery premises bottles nearly seven million cylinder per annum for

catering domestic market. Major fertilizer industries at Kanpur, Panipat,

Nangal, Bhatinda, and Kota are supplied with Naphtha or furnace oil. Also

thermal power plants of Nangal, Obra, and Badarpur get fuel oil supply from

this refinery.

Mathura refinery was the first in Asia and third refinery in the world to have

been honored with the coveted ISO- 14001, certification on July 22- 1996.

It was also awarded the Golden peacock national quality award 1996.

It bagged first prize in national energy conservation award in 1996 in public

sector in ministry of power.

Jawaharlal Nehru Cenetery award for achieving the best improved method of

energy conservation compared to its past best performance of 1994 & 1996.

Highest ever ATF (AVIATION TURBINE FUEL) and bitumen production of

617.6 & 430.2 TMT achieved surpassing the previous best of 613.4 TMT in

1993/94 & 425.2 TMT in 1993-94 respectively. Highest ever distillated yield of

73.14% on crude achieved surpassing of previous best of 72.78% on crude in

1987-88.

VISION: A major diversified, translational, integrated energy company, with national

leadership and a strong environment conscience, playing a national role in oil

security and public distribution.

MISSION:

► To achieve international standards of excellence in all aspects of energy

and diversified business with focus on customer delight through value of

products and services and cost reduction.

► To maximize creation of wealth, value and satisfaction for the stakeholders.

► To attain leadership in developing, adopting and assimilating state of the

art technology for competitive advantage.

► To provide technology and services through sustained research and

development.

► To cultivate high standards of business ethics and total quality

management for a strong corporate identity and brand equity.

► To help enrich the quality of life of the community and preserve ecological

balance and heritage through a strong environment conscience.

1. ATMOSPHERIC AND VACUUM DISTILLATION

UNIT (AVU)

● INTRODUCTION: -

The ADU (Atmospheric Distillation Unit) separates most of the lighter end

products such as gas, gasoline, naphtha, kerosene, and gas oil from the

crude oil. The bottoms of the ADU are then sent to the VDU (Vacuum

Distillation Unit).

Crude oil is preheated by the bottoms feed exchanger, further preheated and

partially vapourized in the feed furnace and then passed into the atmospheric

tower where it is separated into off gas, gasoline, naphtha, kerosene, gas oil

and bottoms.

Atmospheric and Vacuum unit (AVU) of Mathura Refinery is designed to

process 100% Bombay High Crude and 100% Arab Mix crude (consisting of

Light and Heavy crude in 50:50 proportion by weight) in blocked out operation

@ 11.0 MMTPA.

AVU consists of following sections:

► Crude Desalting section

► Atmospheric Distillation section

► Stabilizer section

► Vacuum Distillation section

TYPES OF CRUDE: ► Low Sulphur

Indian: Bombay High Nigerian: Girasol, Farcados, Bonny light

► High Sulphur

Imported: Arab Mix, Kuwait, Dubai, Ratawi, Basra etc

PRODUCTS FROM CDU/VDU MAIN COLUMNS

VACUUM DISTILLATION UNIT

Hot RCO from the atmospheric column bottom at 355 ºC is mixed with slop

recycle from vacuum column, heated and partially vapourized in 8-pass

vacuum furnace and introduced to the flash zone of the vacuum column. The

flash zone pressure is maintained at 115-120 mm of Hg. Steam (MP) is

injected into individual passes and regulated manually. Three injection points

have been provided on each pass. This is to maintain required velocities in

the heater, which is Fuel Gas, Fuel Oil or combination fuel fired. Each cell is

provided with 10 burners fired vertically upshot from furnace floor along the

centerline of the cell.

The vapourized portions entering the flash zone of the column along with

stripped light ends from the bottoms rise up in the vacuum column and are

fractionated into four side stream products in 5 packed sections. The

hydrocarbon vapours are condensed in the Vac Slop, HVGO, LDO and LVGO

sections by circulating refluxes to yield the side draw products.

Vacuum is maintained by a two-stage ejector system with surface

condensers. The condensed portion from the condensers are routed to the

hot well from where the non-condensable are sent to the vacuum furnace low-

pressure burners or vented to the atmosphere. Oil carried over along with the

steam condensate is pumped to the vacuum diesel rundown line by overhead

oil pumps.

2. FLUID CATALYTIC CRAKING UNIT (FCCU)

In the newer designs for Fluid Catalytic Cracking Unit, cracking takes place

using a very active zeolite-based catalyst in a short-contact time vertical or

upward sloped pipe called the "riser". Pre-heated feed is sprayed into the

base of the riser via feed nozzles where it contacts extremely hot fluidized

catalyst at 1230 to 1400 °F (665 to 760 °C). The ho t catalyst vapourizes the

feed and catalyzes the cracking reactions that break down the high molecular

weight oil into lighter components including LPG, gasoline, and diesel. The

catalyst-hydrocarbon mixture flows upward through the riser for just a few

seconds and then the mixture is separated via cyclones. The catalyst-free

hydrocarbons are routed to a main fractionator for separation into fuel gas,

LPG, gasoline, light cycle oils used in diesel and jet fuel, and heavy fuel oil.

During the trip up the riser, the cracking catalyst is "spent" by reactions which

deposit coke on the catalyst and greatly reduce activity and selectivity. The

"spent" catalyst is disengaged from the cracked hydrocarbon vapours and

sent to a stripper where it is contacted with steam to remove hydrocarbons

remaining in the catalyst pores. The "spent" catalyst then flows into a

fluidized-bed regenerator where air (or in some cases air plus oxygen) is used

to burn off the coke to restore catalyst activity and also provide the necessary

heat for the next reaction cycle, cracking being an endothermic reaction. The

"regenerated" catalyst then flows to the base of the riser, repeating the cycle.

The gasoline produced in the FCC unit has an elevated octane rating but is

less chemically stable compared to other gasoline components due to its

olefin profile. Olefins in gasoline are responsible for the formation of polymeric

deposits in storage tanks, fuel ducts and injectors. The FCC LPG is an

important source of C3-C4 olefins and isobutane that are essential feeds for

the alkylation process and the production of polymers such as polypropylene.

In this process Heavy Gas Oil cut (Raw Oil) from Vacuum Distillation Section

of AVU is catalytically cracked to obtain more valuable light and middle

distillates. The present processing capacity of the unit is about 1.48 MMT/Yr.

It consists of the following sections:

● Cracking section,

● Catalytic section,

● Fractionation section and

● Gas concentration section.

● CO boiler

The unit is designed to process two different types of feed i.e. Arab Mix

HVGO and Bombay High HVGO.

3. CONTINUOUS CATALYTIC REFORMING UNIT

(CCRU)

A catalytic reforming process converts a feed stream containing paraffins,

Olefins and naphthene to aromatics. The product stream of the reformer is

generally referred to as reformate. Reformate produced by this process has a

very high octane rating. Significant quantities of hydrogen are also produced

as a by-product. Catalytic reforming is normally facilitated by a bi-functional

catalyst that is capable of rearranging and breaking long-chain hydrocarbons

as well as removing hydrogen from naphthenes to produce aromatics. The

idea of a Catalytic Reforming Unit is to have RON (Research Octane Number)

as high as possible at the same time keeping the Olefins, Benzene &

Aromatics under the specified limits. The different types of reformers are

classified as a fixed-bed type, semi-regenerative type, cyclic type and the

continuous regenerative type. This classification is based on the ability of the

unit to operate without bringing down the catalyst for Regeneration. During the

regeneration process, the refinery will suffer production loss. In the

Continuous Catalytic Reforming unit, the reactors are cleverly stacked, so that

the catalyst can flow under gravity. From the bottom of the reactor stack, the

'spent' catalyst is 'lifted' by nitrogen to the top of the regenerator stack. In the

regenerator, the above mentioned different steps, coke burning,

oxychlorination and drying are done in different sections, segregated via a

complex system of valves, purge-flows and screens. From the bottom of the

regenerator stack, catalyst is lifted by hydrogen to the top of the reactor stack,

in a special area called the reduction zone. In the reduction zone, the catalyst

passes a heat exchanger in which it is heated up against hot feed. Under hot

conditions it is brought in contact with hydrogen, which performs a reduction

of the catalyst surface, thereby restoring its activity. In such a continuous

regeneration process, a constant catalyst activity can be maintained without

unit shut down for a typical run length of 3 - 6 years. The purpose of the CCR

unit is to produce a high octane no. reformate. The octane no. of the gasoline

coming from the AVU is around 66, whereas the required value of the octane

no. is 87, 88 and 93.

The whole CRU can be divided into three subunits as:

● Naphtha Splitting Unit (NSU)

● Naphtha Hydro-treater Unit (NHU)

● Catalytic Reforming Unit

► NAPHTHA SPLITTING UNIT

This unit has been designed to split SR naphtha (144 MT/hr for BH and 95

MT/hr for AM) to C5-80 oC and 80-115 oC cut. Due to the restriction on

Benzene content in the final product (motor spirit), the IBP of the heavier cut

is raised to approximately 105 oC. NSU can be operated with naphtha directly

from AVU (hot feed) and from OM&S (Cold feed), it can also be operated

using both the feed simultaneously. For removal of benzene, the gasoline

from storage tanks and CDU is sent to a column, containing 40 valve trays,

which is called naphtha splitter. The bottom product of naphtha splitter is sent

to the NHU.

► NAPHTHA HYDROTREATER UNIT

The purpose of Naphtha hydrotreater is to eliminate the impurities (such as

sulphur, nitrogen, halogens, oxygen, water, olefins, di-olefins, arsenic and

metals) from the feed that would otherwise affect the performance and lifetime

of reformer catalyst. This is achieved by the use of selected catalyst (nickel,

molybdenum) and optimum operating conditions except for water, which is

eliminated in stripper.

In this unit, the naphtha coming from the NSU is mixed with H2 which comes

from the reforming unit. This mixture is heated to 340 OC in the furnace and

then passed to the hydrotreater reactor at a pressure of 22 kg/cm2.

In the reactor, there are two beds of catalyst. In one bed, the unsaturated

hydrocarbons are converted to saturated hydrocarbons and in the second bed

impurities like N, S, and O are converted to NH3, H2S and H2O respectively.

The effluent of the reactor is sent to stripper section to eliminate the light end,

mainly the H2S and moisture from the reformate feed. The light gases from

the top of stripper are sent to amine wash unit.

There is a reboiler attached to the bottom of the stripper, which maintains the

heat requirement. The bottom product of the stripper is either sent to storage

or the reforming unit.

► REFORMING UNIT

Feed for the Reforming unit (94 m3/hr at 14 kg/cm2 and 110 ºC) is received

directly from hydrotreater stripper after heat exchanger. The filters must be

provided for the protection of the welded plate exchanger. Feed is filtered to

remove any foreign particles. At the D/S of the feed filter, chloriding agent and

water injection are done. CCl4 solution of 1% in reformate is dosed by pump.

Dosing @ 1 ppm wt CCl4 in feed is done when continuous regeneration unit is

down. Water injection (not on regular basis) is done to maintain Cl-OH

equilibrium on the catalyst when regenerator is out of service.

Feed mixed with recycle H2 stream gets preheated in PACKINOX exchanger

from 91ºC to 451ºC by the effluent from 3rd Reactor which gets cooled down

from 497ºC to 98ºC.

Due to the endothermic nature of the reforming reactions, the overall

reforming is achieved in stages with inter stage heater provided to raise the

temperature. There are three Reactors (15R-1, R-2 & R-3) each provided with

reaction heater.

4. ONCE THROUGH HYDROCRACKER UNIT (OHCU)

Hydro Cracking Unit is designed for 1.2 MMT/year (165.6 m³/hr, 25,000

BPSD). The objective of the Hydro Cracking Unit is to produce middle

distillate fuel of superior quality. The unit is designed to process two different

types of feed i.e. Arab Mix HVGO, Bombay High HVGO. All the H2S will be

removed by absorbing in DEA.

PROCESS DESCRIPTION:

The Hydrocracker Unit consists of four principle sections:

● Make-Up Hydrogen Compression

● Reaction Section

● Fractionation Section

● Light Ends Recovery Section

► REACTOR FEED SYSTEM:

Fresh feed to the Hydrocracker consists of a blend of Arab Mix and Bombay

High VGO. The feed control system allows the operator to control the ratio of

Arab Mix and Bombay High VGOs in order to set the relative rates of each.

The preheated and filtered oil feed is combined with a preheated mixture of

make-up hydrogen from the make-up hydrogen compression section and

hydrogen-rich recycle gas from the recycle gas compressor in a gas-to-oil

ratio of 845 Nm3/m3.The reactor system contains one reaction stage

consisting of two reactors in series in a single high-pressure loop. The lead

and main reactors contain hydro treating and hydro cracking catalyst (Si/Al

with Ni-Co-Fe) for denitrification, desulphurization, and conversion of the raw

feed to products.

The reactor effluent is initially cooled by heat exchange with the VGO feed

and then by heat exchange with recycle gas and with the product fractionator

feed. The effluent is then used to generate medium pressure [12.0 kg/cm2 (g)]

steam.

► FRACTIONATION SECTION:

The fractionation section consisting of the fractionator, side cut strippers, and

heat exchange equipment is designed to separate conversion products from

unconverted feed. The reaction products recovered from the column are Sour

Gas (Off gas), Unstable Light Naphtha, Heavy Naphtha, Kerosene, Diesel and

FCC Feed. The fractionator off-gas and unstable light naphtha are sent to the

light ends recovery section for recovery of LPG and light naphtha product.

► DE-ETHANISER:

The de-ethaniser remove light ends (C2), H2S, and water from the light

naphtha and LPG. Feed enters the top of the column. The feed to the de-

ethaniser comes from the combined liquid stream leaving the de-ethaniser

reflux drum and is pumped to the top of the de-ethaniser.

5. DIESEL HYDRO DESULFURIZATION UNIT

(DHDS)

DHDS (Diesel hydro desulphurization unit) is set up for the following

purposes:

● A step towards pollution control

● To produce low sulphur diesel (0.25 w/w %) as per govt. directive w.e.f. Oct.

1999.

Feed consists of different proportion of straight run LGO, HGO, LVGO and

TCO. Mainly two proportions are used:

● 74% SR LGO, 21% SR HGO, 5% SR LVGO

● 48% SR LGO, 24% SR HGO, 8% SR LVGO, 20% TCO

The DHDS unit treats different gas oils from various origins, straight run or

cracked products. The feed is a mixture of products containing unsaturated

components (diolefins, olefins), Aromatics, Sulfur compounds and Nitrogen

compounds. Sulfur and nitrogen contents are dependent upon the crude.

The purpose of DHDS Unit is to hydro-treat a blend of straight run gas oil and

cracked gas oil (TCO) for production of HSD of sulfur content less than 500

ppm wt.

The Hydrodesulphurization reaction releases H2S in gaseous hydrocarbon

effluents. This H2S removal is achieved by means of a continuous absorption

process using a 25% wt. DEA solution.

In addition to the desulphurization, the diolefins and olefins will be saturated

and a denitrification will occur. Denitrification improves the product stability.

The hydrogen is supplied from the hydrogen unit. Lean amine for absorption

operation is available from Amine Regeneration Unit (ARU). Rich Amine

containing absorbed H2S is sent to ARU for amine regeneration.

CATALYSTS:

Catalysts used for this process are HR-945 and HR-348/448.The HR-945 is a

mixture of nickel and molybdenum oxides on a special support. Nickel has

been selected because it boosts the hydrogenating activity. The HR-348 and

HR-448 are desulphurization catalysts; it consists of cobalt and molybdenum

oxides dispersed on an active alumna. Its fine granulometry and large surface

area allow a deep desulphurization rate.

Different catalysts based on Nickel and Molybdenum Oxide are used to

enhance the rate of reactions.

PROCESS VARIABLES: ► HYDROGEN PARTIAL PRESSURE

The hydrogen partial pressure has to be kept as high as possible, in order to

favour the desirable reactions:

● Hydrodesulphurization

● Hydrogenation of nitrogen and oxygen compounds

High hydrogen partial pressure decreases the undesirable reactions of:

● Hydro cracking

● Coking

► TEMPERATURE The reaction temperature must be kept as low as possible because the most

desirable reactions do not need high temperature to remain at desirable rates.

● Hydrodesulphurization

● Hydrogenation of nitrogen and oxygen compounds.

6. HYDROGEN GENERATION UNIT (HGU)

The Unit is designed to process Straight Run Naphtha or Natural Gas to

hydrogen that will cater to the needs of the new DHDT-MSQ and other units.

The process involved for converting the Naphtha to hydrogen is steam

reforming. Process licensor for HGU is HTAS, Denmark. The plant is divided

into 3 sections: -

● Desulphurization

● Reforming

● CO-Conversion

FEED: -

The hydrogen generation unit can be fed either by naphtha or natural gas.

The naphtha feed is pressurized to about 35 Kg/cm2g by one of the naphtha

feed pumps and sent to the desulphurization section.

The pressurized feed is mixed with recycle hydrogen from the hydrogen

header. The liquid naphtha is evapourated to one of the naphtha feed

vapourizers. The hydrocarbon feed is heated to 380°-400° C by heat

exchange with superheated steam in the naphtha feed pre-heater.

7. BITUMEN BLOWING UNIT (BBU)

Asphaltic bitumen, normally called "bitumen" is obtained by vacuum distillation

or vacuum flashing of an atmospheric residue. This is “straight run" bitumen.

An alternative method of bitumen production is by precipitation from residual

fractions by propane or butane- solvent de-asphalting.

The bitumen thus obtained has properties which are derived from the type of

crude oil processed and from the mode of operation in the vacuum unit or in

the solvent de-asphalting unit. The grade of the bitumen depends on the

amount of volatile material that remains in the product: the smaller the amount

of volatiles, the harder the residual bitumen. The blowing process for bitumen

preparation is carried out continuously in a blowing column. The liquid level in

the blowing column is kept constant by means of an internal draw-off pipe.

This makes it possible to set the air-to-feed ratio (and thus the product quality)

by controlling both air supply and feed supply rate. The feed to the blowing

unit (at approximately 210 0C), enters the column just below the liquid level

and flows downward in the column and then upward through the draw-off

pipe. Air is blown through the molten mass (280-300 0C) via an air distributor

in the bottom of the column. The bitumen and air flow are countercurrent, so

that air low in oxygen meets the fresh feed first. This, together with the mixing

effect of the air bubbles jetting through the molten mass, will minimise the

temperature effects of the exothermic oxidation reactions, local overheating

and cracking of bituminous material. The blown bitumen is withdrawn

continuously from the surge vessel under level control and pumped to storage

through feed/product heat exchangers. Air residue having boiling point 530oC

(TBP) is obtained from North Rumaila crude. Air blowing of vacuum residue at

high temperature considerably increases the contents of gums and

asphaltenes at the expense of conversion of a portion of hydrocarbon into

condensed oil. Bitumen is a colloidal solution of asphaltenes and associated

high molecular gums in the medium formed by oils and low molecular gums.

Asphaltene content in the bitumen influences its solidity and softening point.

The higher the asphaltene content, the more solid is the bitumen. Gums

increase bitumen binding properties and elasticity.

FEED SUPPLY SYSTEM: -

The feed to the unit consists of hot SR taken directly from the vacuum unit or

cold residue from tanks. The hot feed goes to reactors at 200-210oC in two

parallel streams. Flow control valves control feed flow to individual reactors.

As refinery would be processing both Imported and Bombay high crude in

blocked out cyclic operation, the unit will not get hot feed during the period

AVU processes indigenous crude. To avoid shut down of BBU under such

circumstances or when VDU is down the unit will be supplied cold feed from

the tanks.

BITUMEN FURNACE: -

It is a natural draft furnace with convection and radiation sections. The

convection section forms rectangular box while radiation zone is cylindrical in

shape. The two sections are having horizontal and vertical feed coils

respectively. Pumps supply cold feed to furnace at temperature of 150-180oC.

Furnace has two coil passes. Provision also exists to operate the furnace as a

simple coil pass while operating at low turndown ratio. Feed enters through

convection zone at the top and control valves control flow of each stream. The

furnace is provided with one oil-cum-gas burner at its base. The feed first

picks up heat from the flue gases in the convection section and then it is

heated in the radiation zone coils. The feed is heated up to 230oC. The two

passes join together at the outlet of furnace and are routed to reactors in two

parallel streams.

FINISHED BITUMEN CIRCUIT: -

Finished bitumen from the reactors at 240-260oC is pumped in parallel

streams and cooled in two groups of air-coolers up to 170-200oC. Cooled

bitumen is routed to storage tanks through two separate rundown lines.

8. SULFUR RECOVERY UNIT (SRU)

The unit consists of three identical units A, B and C. One of them is kept

standby. The process design is in accordance with common practice to

recover elemental sulfur known as the Clause process, which is further

improved by Super Clause process. Each unit consists of a thermal stage, in

which H2S is partially burnt with air, followed by two catalytic stages. A

catalytic incinerator for incineration of all gases has been incorporated in

order to prevent pollution of the atmosphere.

The primary function of the waste heat boiler is to remove the major portion of

heat involved in the combustion chamber. The secondary function of waste

heat boiler is to condense the sulphur, which is drained to a sulphur pit. At this

stage 60% of the sulphur present in the sour gas feed is removed. The third

function of the waste heat boiler is to utilize the heat liberated there to

produce LP steam (4 kg/cm2).

The process gas leaving the waste heat boiler still contains a considerable

part of H2S and SO2. Therefore, the essential function of the following

equipment is to shift the equilibrium by adopting a low reactor temperature

thus removing the sulphur as soon as it is formed.

Conversion to sulphur is reached by a catalytic process in two subsequent

reactors containing a special synthetic alumina catalyst.

Before entering the first reactor, the process gas flow is heated to an optimum

temperature by means of a line burner, with mixing chamber, in order to

achieve a high conversion. In the line burner mixing chamber the process gas

is mixed with the hot flue gas obtained by burning fuel gas with air.

In the first reactor the reaction between the H2S and SO2 recommences until

equilibrium is reached. The effluent gas from the first reactor passes to the

first sulphur condenser where at this stage approximately 29% of the sulphur

present in the sour gas feed is condensed and drained to the sulphur pit. The

total sulphur recovery after the first reactor stage is 89% of the sulphur

present in the sour gas feed. In order to achieve a figure of 94% sulphur

recovery the sour gas is subjected to one more stage.

The process gas flow is once again subjected to preheating by means of a

second line burner then passed to a second reactor and the sulphur

condensed in a second condenser accomplish a total sulphur recovery of

94%. A sulphur coalescer is installed downstream the last sulphur condenser

to separate entrained sulphur mist. The heat released by the subsequent

cooling of gas and condensation of sulphur in waste heat boiler and, sulphur

condensers results in the production of low-pressure steam.

9. QUALITY CONTROL LABORATORY

Quality control is the primary function of the laboratory, assisting the

Refinery’s Production Units by providing them with quality control data on the

product streams at regular intervals. Apart from routine tests, the laboratory

also handles investigation problems, analysis of process chemicals and water

analysis. It is responsible for certification of the finished products produced

and dispatched by Mathura Refinery.

Mathura Refinery QC Laboratory has five main sections:

1. Process Control Laboratory.

2. Finished Product Laboratory.

3. Analytical and Development Laboratory.

4. ATF Laboratory.

5. Pollution Control Laboratory.

EQUIPMENTS

► COMPRESSOR: -

A gas compressor is a mechanical device that increases the pressure of

a gas by reducing its volume.

Compressors are similar to pumps: both increase the pressure on a fluid and

both can transport the fluid through a pipe. As gases are compressible, the

compressor also reduces the volume of a gas. Liquids are relatively

incompressible, while some can be compressed, the main action of a pump is

to pressurize and transport liquids.

TYPES OF COMPRESSORS: -

The main types of gas compressors are discussed below:

● Reciprocating compressors: -

Reciprocating compressors use pistons driven by a crankshaft. They can

be either stationary or portable, can be single or multi-staged, and can be

driven by electric motors or internal combustion engines. Small reciprocating

compressors from 5 to 30 horsepower (hp) are commonly seen in automotive

applications and are typically for intermittent duty. Larger reciprocating

compressors well over 1,000 hp (750 kW) are commonly found in large

industrial and petroleum applications. Discharge pressures can range from

low pressure to very high pressure (>18000 psi or 180 MPa). In certain

applications, such as air compression, multi-stage double-acting compressors

are said to be the most efficient compressors available, and are typically

larger, and more costly than comparable rotary units. Another type of

reciprocating compressor is the swash plate compressor, which uses pistons

which are moved by a swash plate mounted on a shaft - see Axial Piston

Pump.

Household, home workshop, and smaller job site compressors are typically

reciprocating compressors 1½ hp or less with an attached receiver tank.

Fig: A motor-driven six-cylinder reciprocating compressor that can operate with two, four or six cylinders.

● Centrifugal compressors: -

Centrifugal compressors use a rotating disk or impeller in a shaped housing

to force the gas to the rim of the impeller, increasing the velocity of the gas.

A diffuser (divergent duct) section converts the velocity energy to pressure

energy. They are primarily used for continuous, stationary service in industries

such as oil refineries, chemical and petrochemical plants and natural gas

processing plants. Their application can be from 100 horsepower (75 kW) to

thousands of horsepower. With multiple staging, they can achieve extremely

high output pressures greater than 10,000 psi (69 MPa).

Many large snowmaking operations use this type of compressor. They are

also used in internal combustion engines assuperchargers and turbochargers.

Centrifugal compressors are used in small gas turbine engines or as the final

compression stage of medium sized gas turbines. Sometimes the capacity of

the compressors is written in NM3/hr. Here 'N' stands for normal temperature

pressure (20°C and 1 atm) for example 5500 NM3/hr.

Fig: A single stage centrifugal compressor

● Rotary vane compressors: -

Rotary vane compressors consist of a rotor with a number of blades

inserted in radial slots in the rotor. The rotor is mounted offset in a larger

housing which can be circular or a more complex shape. As the rotor turns,

blades slide in and out of the slots keeping contact with the outer wall of the

housing. Thus, a series of decreasing volumes is created by the rotating

blades. Rotary Vane compressors are, with piston compressors one of the

oldest of compressor technologies.

With suitable port connections, the devices may be either a compressor or a

vacuum pump. They can be either stationary or portable, can be single or

multi-staged, and can be driven by electric motors or internal combustion

engines. Dry vane machines are used at relatively low pressures (e.g., 2 bar

or 200 kPa; 29 psi) for bulk material movement while oil-injected machines

have the necessary volumetric efficiency to achieve pressures up to about

13 bar (1,300 kPa; 190 psi) in a single stage. A rotary vane compressor is well

suited to electric motor drive and is significantly quieter in operation than the

equivalent piston compressor.

Rotary vane compressors can have mechanical efficiencies of about 90%.

► PUMP: -

A pump is a device used to move fluids, such as liquids, gases or slurries.

A pump displaces a volume by physical or mechanical action. Pumps fall into

three major groups: direct lift, displacement, and gravity pumps. Their

names describe the method for moving a fluid.

TYPES: -

● Positive Displacement Pumps:

A positive displacement pump causes a fluid to move by trapping a fixed

amount of it then forcing (displacing) that trapped volume into the discharge

pipe.

or

A positive displacement pump has an expanding cavity on the suction side

and a decreasing cavity on the discharge side. Liquid flows into the pump as

the cavity on the suction side expands and the liquid flows out of the

discharge as the cavity collapses. The volume is constant given each cycle of

operation.

A positive displacement pump can be further classified according to the

mechanism used to move the fluid:

� Rotary-type, internal gear, screw, shuttle block, flexible vane or sliding

vane, circumferential piston, helical twisted roots (e.g. the Wendelkolben

pump) or liquid ring vacuum pumps.

Positive displacement rotary pumps are pumps that move fluid using the

principles of rotation. The vacuum created by the rotation of the pump

captures and draws in the liquid. Rotary pumps are very efficient because

they naturally remove air from the lines, eliminating the need to bleed the air

from the lines manually.

Positive displacement rotary pumps also have their weaknesses. Because of

the nature of the pump, the clearance between the rotating pump and the

outer edge must be very close, requiring that the pumps rotate at a slow,

steady speed. If rotary pumps are operated at high speeds, the fluids will

cause erosion. Rotary pumps that experience such erosion eventually show

signs of enlarged clearances, which allow liquid to slip through and reduce the

efficiency of the pump.

Positive displacement rotary pumps can be grouped into three main types.

Gear pumps are the simplest type of rotary pumps, consisting of two gears

laid out side-by-side with their teeth enmeshed. The gears turn away from

each other, creating a current that traps fluid between the teeth on the gears

and the outer casing, eventually releasing the fluid on the discharge side of

the pump as the teeth mesh and go around again. Many small teeth maintain

a constant flow of fluid, while fewer, larger teeth create a tendency for the

pump to discharge fluids in short, pulsing gushes.

Screw pumps are a more complicated type of rotary pumps, featuring two or

three screws with opposing thread —- that is, one screw turns clockwise, and

the other counterclockwise. The screws are each mounted on shafts that run

parallel to each other; the shafts also have gears on them that mesh with

each other in order to turn the shafts together and keep everything in place.

The turning of the screws, and consequently the shafts to which they are

mounted, draws the fluid through the pump. As with other forms of rotary

pumps, the clearance between moving parts and the pump's casing is

minimal.

Moving vane pumps are the third type of rotary pumps, consisting of a

cylindrical rotor encased in a similarly shaped housing. As the rotor turns, the

vanes trap fluid between the rotor and the casing, drawing the fluid through

the pump.

� Reciprocating-type, for example, piston or diaphragm pumps.

Positive displacement pumps have an expanding cavity on the suction side

and a decreasing cavity on the discharge side. Liquid flows into the pumps as

the cavity on the suction side expands and the liquid flows out of the

discharge as the cavity collapses. The volume is constant given each cycle of

operation.

The positive displacement pumps can be divided into two main classes

� reciprocating

� rotary

● Gear pump: This uses two meshed gears rotating in a closely fitted

casing. Fluid is pumped around the outer periphery by being trapped in the

tooth spaces. It does not travel back on the meshed part, since the teeth

mesh closely in the centre. Widely used on car engine oil pumps. It is also

used in various hydraulic power packs.

● Centrifugal pump: A centrifugal pump is a rotodynamic pump that uses

a rotating impeller to increase the pressure and flow rate of a fluid. Centrifugal

pumps are the most common type of pump used to move liquids through a

piping system. The fluid enters the pump impeller along or near to the rotating

axis and is accelerated by the impeller, flowing radially outward or axially into

a diffuser or volute chamber, from where it exits into the downstream piping

system. Centrifugal pumps are typically used for large discharge through

smaller heads.

Centrifugal pumps are most often associated with the radial flow type.

However, the term "centrifugal pump" can be used to describe all impeller

type rotodynamic pumps including the radial, axial and mixed flow variations.

► HEAT EXCHANGER: -

A heat exchanger is a piece of equipment built for efficient heat transfer from

one medium to another. The media may be separated by a solid wall, so that

they never mix, or they may be in direct contact.[1] They are widely used

in space heating, refrigeration, air conditioning,power plants, chemical

plants, petrochemical plants, petroleum refineries, natural gas processing,

and sewage treatment. One common example of a heat exchanger is

the radiator in a car, in which the heat source, being a hot engine-cooling

fluid, water, transfers heat to air flowing through the radiator (i.e. the heat

transfer medium).

Types of heat exchangers: -

● Shell and tube heat exchanger: - Shell and tube heat exchangers consist of a series of tubes. One set of these

tubes contains the fluid that must be either heated or cooled. The second fluid

runs over the tubes that are being heated or cooled so that it can either

provide the heat or absorb the heat required. A set of tubes is called the tube

bundle and can be made up of several types of tubes: plain, longitudinally

finned, etc. Shell and tube heat exchangers are typically used for high-

pressure applications (with pressures greater than 30 bar and temperatures

greater than 260°C). This is because the shell and tube heat exchangers are

robust due to their shape.

There are several thermal design features that are to be taken into account

when designing the tubes in the shell and tube heat exchangers. These

include:

� Tube diameter: Using a small tube diameter makes the heat exchanger

both economical and compact. However, it is more likely for the heat

exchanger to foul up faster and the small size makes mechanical cleaning

of the fouling difficult. To prevail over the fouling and cleaning problems,

larger tube diameters can be used. Thus to determine the tube diameter,

the available space, cost and the fouling nature of the fluids must be

considered.

� Tube thickness: The thickness of the wall of the tubes is usually

determined to ensure:

� There is enough room for corrosion

� That flow-induced vibration has resistance

� Axial strength

� Availability of spare parts

� Hoop strength (to withstand internal tube pressure)

� Buckling strength (to withstand overpressure in the shell)

� Tube length: heat exchangers are usually cheaper when they have a

smaller shell diameter and a long tube length. Thus, typically there is an

aim to make the heat exchanger as long as physically possible whilst not

exceeding production capabilities. However, there are many limitations for

this, including the space available at the site where it is going to be used

and the need to ensure that there are tubes available in lengths that are

twice the required length (so that the tubes can be withdrawn and

replaced). Also, it has to be remembered that long, thin tubes are difficult

to take out and replace.

� Tube pitch: when designing the tubes, it is practical to ensure that the

tube pitch (i.e., the centre-centre distance of adjoining tubes) is not less

than 1.25 times the tubes' outside diameter. A larger tube pitch leads to a

larger overall shell diameter which leads to a more expensive heat

exchanger.

� Tube corrugation: this type of tubes, mainly used for the inner tubes,

increases the turbulence of the fluids and the effect is very important in the

heat transfer giving a better performance.

� Tube Layout: refers to how tubes are positioned within the shell. There

are four main types of tube layout, which are, triangular (30°), rotated

triangular (60°), square (90°) and rotated square ( 45°). The triangular

patterns are employed to give greater heat transfer as they force the fluid

to flow in a more turbulent fashion around the piping. Square patterns are

employed where high fouling is experienced and cleaning is more regular.

Baffle Design: baffles are used in shell and tube heat exchangers to direct

fluid across the tube bundle. They run perpendicularly to the shell and hold

the bundle, preventing the tubes from sagging over a long length. They

can also prevent the tubes from vibrating. The most common type of baffle

is the segmental baffle. The semicircular segmental baffles are oriented at

180 degrees to the adjacent baffles forcing the fluid to flow upward and

downwards between the tube bundle. Baffle spacing is of large

thermodynamic concern when designing shell and tube heat exchangers.

Baffles must be spaced with consideration for the conversion of pressure

drop and heat transfer. For thermo economic optimization it is suggested

that the baffles be spaced no closer than 20% of the shell’s inner diameter.

Having baffles spaced too closely causes a greater pressure drop because

of flow redirection. Consequently having the baffles spaced too far apart

means that there may be cooler spots in the corners between baffles. It is

also important to ensure the baffles are spaced close enough that the

tubes do not sag. The other main type of baffle is the disc and donut baffle

which consists of two concentric baffles, the outer wider baffle looks like a

donut, whilst the inner baffle is shaped as a disk. This type of baffle forces

the fluid to pass around each side of the disk then through the donut baffle

generating a different type of fluid flow.

Fig: A Shell and Tube heat exchanger

► STEAM TURBINE: -

A steam turbine is a mechanical device that extracts thermal energy from

pressurized steam, and converts it into rotary motion. Its modern

manifestation was invented by Sir Charles Parsons in 1884.

It has almost completely replaced the reciprocating piston steam

engine primarily because of its greater thermal efficiency and higher power-to-

weight ratio. Because the turbine generates rotary motion, it is particularly

suited to be used to drive an electrical generator – about 80% of all electricity

generation in the world is by use of steam turbines. The steam turbine is a

form of heat engine that derives much of its improvement in thermodynamic

efficiency through the use of multiple stages in the expansion of the steam,

which results in a closer approach to the ideal reversible process.

● Turbine efficiency: -

To maximize turbine efficiency the steam is expanded, doing work, in a

number of stages. These stages are characterized by how the energy is

extracted from them and are known as either impulse or reaction turbines.

Most steam turbines use a mixture of the reaction and impulse designs: each

stage behaves as either one or the other, but the overall turbine uses both.

Typically, higher pressure sections are impulse type and lower pressure

stages are reaction type.

● Impulse turbines: -

An impulse turbine has fixed nozzles that orient the steam flow into high

speed jets. These jets contain significant kinetic energy, which the rotor

blades, shaped like buckets, convert into shaft rotation as the steam jet

changes direction. A pressure drop occurs across only the stationary blades,

with a net increase in steam velocity across the stage.

As the steam flows through the nozzle its pressure falls from inlet pressure to

the exit pressure (atmospheric pressure, or more usually, the condenser

vacuum). Due to this higher ratio of expansion of steam in the nozzle the

steam leaves the nozzle with a very high velocity. The steam leaving the

moving blades has a large portion of the maximum velocity of the steam when

leaving the nozzle. The loss of energy due to this higher exit velocity is

commonly called the "carry over velocity" or "leaving loss".

● Reaction turbines: -

In the reaction turbine, the rotor blades themselves are arranged to form

convergent nozzles. This type of turbine makes use of the reaction force

produced as the steam accelerates through the nozzles formed by the rotor.

Steam is directed onto the rotor by the fixed vanes of the stator. It leaves the

stator as a jet that fills the entire circumference of the rotor. The steam then

changes direction and increases its speed relative to the speed of the blades.

A pressure drop occurs across both the stator and the rotor, with steam

accelerating through the stator and decelerating through the rotor, with no net

change in steam velocity across the stage but with a decrease in both

pressure and temperature, reflecting the work performed in the driving of the

rotor.

► Superheater:

A superheater is a device used to convert saturated steam or wet steam into dry

steam used for power generation or processes. There are three types of

superheaters namely: radiant, convection, and separately fired. A superheater can

vary in size from a few tens of feet to several hundred feet (a few metres or some

hundred metres).

A radiant superheater is placed directly in the combustion chamber.

A convection superheater is located in the path of the hot gases.

A separately fired superheater, as its name implies, is totally separated from the

boiler.

A superheater is a device in a steam engine, when considering locomotives, that

heats the steam generated by the boiler again, increasing its thermal energy and

decreasing the likelihood that it will condense inside the engine

Superheaters increase the efficiency of the steam engine, and were widely adopted.

Steam which has been superheated is logically known as superheated steam; non-

superheated steam is called saturated steam or wet steam. Superheaters were

applied to steam locomotives in quantity from the early 20th century, to most steam

vehicles, and to stationary steam engines. This equipment is still an integral part of

power generating stations throughout the world.

The main advantages of using a superheater are reduced fuel and water

consumption but there is a price to pay in increased maintenance costs. In most

cases the benefits outweighed the costs and superheaters were widely used. An

exception was shunting locomotives (switchers). Without careful maintenance

superheaters are prone to a particular type of hazardous failure in the tube bursting

at the U-shaped turns in the superheater tube. This is difficult to both manufacture,

and test when installed, and a rupture will cause the superheated high-pressure

steam to escape immediately into the large flues, and then back to the fire and into

the cab, to the extreme danger of the locomotive crew.

► Deaerator: -

A deaerator is a device that is widely used for the removal of air and other dissolved

gases from the feedwater to steam-generating boilers. In particular, dissolved oxygen

in boiler feedwaters will cause serious corrosion damage in steam systems by

attaching to the walls of metal piping and other metallic equipment and forming

oxides (rust). Water also combines with any dissolved carbon dioxide to form

carbonic acid that causes further corrosion. Most deaerators are designed to remove

oxygen down to levels of 7 ppb by weight (0.005 cm³/L) or less.

There are two basic types of deaerators are:

• The tray-type (also called the cascade-type) includes a vertical domed

deaeration section mounted on top of a horizontal cylindrical vessel which

serves as the deaerated boiler feedwater storage tank.

• The spray-type consists only of a horizontal (or vertical) cylindrical vessel

which serves as both the deaeration section and the boiler feedwater storage

tank.

Fig: Tray type deaerator Fig: Spray type deaerator

► Boiler: -

A boiler is a closed vessel in which water or other fluid is heated. The heated

or vaporized fluid exits the boiler for use in various processes or heating

applications.

Configurations: - Boilers can be classified into the following configurations:

Fire-tube boiler. Here, water partially fills a boiler barrel with a small volume

left above to accommodate the steam (steam space). This is the type of boiler

used in nearly all steam locomotives. The heat source is inside a furnace

or firebox that has to be kept permanently surrounded by the water in order to

maintain the temperature of the heating surface just below boiling point. The

furnace can be situated at one end of a fire-tube which lengthens the path of

the hot gases, thus augmenting the heating surface which can be further

increased by making the gases reverse direction through a second parallel

tube or a bundle of multiple tubes (two-pass or return flue boiler); In the case

of a locomotive-type boiler, a boiler barrel extends from the firebox and the

hot gases pass through a bundle of fire tubes inside the barrel which greatly

increase the heating surface compared to a single tube and further improve

heat transfer. Fire-tube boilers usually have a comparatively low rate of steam

production, but high steam storage capacity. Fire-tube boilers mostly burn

solid fuels, but are readily adaptable to those of the liquid or gas variety.

Water-tube boiler. In this type, the water tubes are arranged inside a furnace

in a number of possible configurations: often the water tubes connect large

drums, the lower ones containing water and the upper ones, steam and water;

in other cases, such as a monotube boiler, water is circulated by a pump

through a succession of coils. This type generally gives high steam production

rates, but less storage capacity than the above. Water tube boilers can be

designed to exploit any heat source and are generally preferred in high

pressure applications since the high pressure water/steam is contained within

small diameter pipes which can withstand the pressure with a thinner wall.