a visit to uran plant of ongc

7/23/2019 A visit to Uran Plant of ONGC

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Uran plant, ONGC Mumbai

GIT-12 1 | P a g e

A CASE STUDY

ON

Abrief study of process and equipmentsat ONGC Uran PlantSubmitted at

Oil and Natural Gas Corporation Limited

Uran, Raigad, Maharashtra

Submitted by

Mechanical Engineering Final Year

GLOBAL INSTITUTE OF TECHNOLOGY


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Introduction:

Oil and Natural Gas Corporation is a public sector petroleum company involved inwidescale exploitation of oil as well as natural gas from the Indian mainland as well as

from Arabian Sea and Indian Ocean. ONGC is one among the Indian Governments Navarathna Companies which involves the

most profit making nine public sector companies and hence is one of the most profit

making companies in India.

Foundation:

In August 1956, the Oil and Natural Gas commission was formed. Raised from mere

directorate status to commission, it had enhanced powers. In 1959, these powers were further

enhanced by converting the commission into a statutory body by an act of Indian Parliament.

Oil and Natural Gas Corporation Limited (ONGC) (incorporated on June 23, 1993) is an

Indian Public Sector Petroleum Company. It is a fortune global 500 companies ranked 335 th,

and contributes 51% of Indias crude oil production and 67% of Indias natural gas production

in India. It was set up as a commission on August 14, 1956. Indian government holds 74.14 %

equity stake in this company.

ONGC is one of Asias largest and most active companies involved in exploration and

production of oil .It is involved in exploring for and exploiting hydrocarbons in 26

sedimentary basins of India. It produces 30% of Indias crude oil requirement. It owns and

operates more than 11,000 kilometers of pipelines in India. In 2010, it was ranked 18th in

thePlattsTop 250 Global Energy Company Rankings and is ranked 413st in the

2012Fortune Global 500list. It is the largest company in terms of market cap in India.

ONGC Represents Indias Energy Security

ONGC has single-handedly scripted Indias hydrocarbon saga by:

Establishing 7.38 billion tonnes of In-place hydrocarbon reserves with more than 300discoveries of oil and gas; in fact, 6 out of the 7 producing basins have been discoveredby ONGC: out of these In-place hydrocarbons in domestic acreages, Ultimate Reservesare 2.60 Billion Metric tonnes (BMT) of Oil Plus Oil Equivalent Gas (O+OEG).

Cumulatively produced 851 Million Metric Tonnes (MMT) of crude and 532 BillionCubic Meters (BCM) of Natural Gas, from 111 fields.
http://en.wikipedia.org/wiki/Plattshttp://en.wikipedia.org/wiki/Plattshttp://en.wikipedia.org/wiki/Plattshttp://en.wikipedia.org/wiki/Fortune_Global_500http://en.wikipedia.org/wiki/Fortune_Global_500http://en.wikipedia.org/wiki/Fortune_Global_500http://en.wikipedia.org/wiki/Fortune_Global_500http://en.wikipedia.org/wiki/Platts


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ONGC has bagged 121 of the 235 Blocks (more than 50%) awarded in the 8 rounds ofbidding, under the New Exploration Licensing Policy (NELP) of the IndianGovernment.

ONGCs wholly-owned subsidiary ONGC Videsh Ltd. (OVL) is the biggest Indianmultinational, with 33 Oil & Gas projects (9 of them producing) in 15 countries, i.e.Vietnam, Sudan, South Sudan, Russia, Iraq, Iran, Myanmar, Libya, Cuba, Colombia,Nigeria, Brazil, Syria, Venezuela and Kazakhstan.


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ONGC as Processing Industry:

Any process industry can be solely divided into 4 parts:

1.

Process plant2. Utilities3. Environmental system4. Safety system1. Process Plant:

This part consist the basic purpose of that process industry for which

it has been established. ONGC Uran plant basically produces LPG and other value

added products and pumps the stabilized oil to different refineries. In sum to get this

purpose there is overall two plant:

a)

Co-generation Plantb) Oil and Gas process PlantCo-generation plant can be also sub divided into mainly 3 different process units:

Gas Turbine Boilers(heat recovery steam generation) Gas fired boilersOil and gas process plant can be sub divided into 6 different processing units:

Slug catcher unit Condensate fractionation unit Gas sweetening unit Crude separation unit LPG recovery unit Ethane propane recovery unit

2. Utilities:Utilities plays very important role in any process industry. They provide

support to process plant for the smooth running and continuous production as in our

case. The basic utilities which are very necessary in our case are:

Effluent treatment Instrument air Air dryer Flare system


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Blow down system Soft water system Fuel gas Inert gas system

3. Environment System:This system monitors the effect of plant on environment by continuous

monitoring inside and outside surrounding of plant and always tries to maintain a

minimum national standard of different environmental parameters. If this minimum

standard is not achieved by the plant then government has to shut that industry as per

environmental law. It can be also categorized in two parts:

Primary environmental system:It is directly related to the health precaution and keeps on check on severe

affect on environment like the surrounding temperature, H2S gas concentration in theatmosphere, suspended particles and carbon concentration etc. as these changes

affect the people and works health working or living in the surrounding of the planet.

Secondary environmental system:This system is not related to health but works for the sake of environmental

protection and welfare. Plantation, nitrogens oxide removal system comes under this

system category.

4. Safety system:This system maintains the safe working condition in this plant is very much

prone to fire as the air in the surrounding contains lots of hydrocarbon and oil

vapours. So any small spark can produce large scale destruction. This system consist

of

Firewater unit Gas detection unit Static charge removal unit


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Introduction to Uran plant:

Uran onshore facilities of ONGC is located at longitudinal 720 5535 and latitude 180 5140

(N) approximately 15 M above mean sea level. The site is about 12 km east of Mumbai.

Western Side of the site faces sea and the east side is surrounded by hills. The site is not on a

level land and processing areas are located at different elevations. Site is approachable by all-

weather motor able roads.

The Uran Plant is one of the most important installations not only of the entire ONGC, but

also of the entire nation. It was established in the year 1974 and expanded in stages. It

receives the entire oil and part of natural gas produced in Mumbai offshore oil fields. Both

the oil and gas received from offshore is processed at various units for producing value added

products like LPG, C2-C3, LAN, apart from processing, storage and transportation of oil.

It has been also awarded as the best processing plant in India. It is situated at the outskirts of

Mumbai city, and has an excellent location with mountains on one side and the sea on the

other side. The huge pipelines from the offshore come directly in the Uran plant. The Uran

plant has an area of 5.5sq.km.


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Layout diagram of Uran plant:


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SAFETY MANAGEMENT IN URAN PLANT, URAN

Uran plant accepts safe accident-free and pollution-free environment in & around all our

location at all times and instilling of safety awareness in our employees. To ensure safety of

the locations, risk analysis and safety audits are carried out. Uran plant has safety committeewith participation from senior officers and workers and meetings are conducted regularly.

A.INBUILT SAFETYFacilities at LPG/CSU plant, ONGC Uran are designed and constructed with three level of

Inbuilt Safety.

1. Pre-alarms : - To alert2. Trip-alarms : - In case no action is taken on (1) above the system is tripped

automatically.3. Safety Valves : - In case of failures even at (2) Safety valves release the content

in the closed system. Safety Valves are tested & calibrated once in a year while re-

alarm are tested once in four months and two months respectively.

B.SAFETY SYSTEMThe plant has dedicated safety system with the following salient features.

1. Gas detectors :-Possible gas leakage point has been identified and provided with gas detectors (250

Nos.) along with facilities of audio-visual alarm in the control room.2. Fire Alarm :-

Elaborate fire communicating system spread all over the plant with 147 fire alarms

which give indication of fire & its location to control room & fire station for

quickest response.

3. Smoke detectors/UV detectors :-These have been provided with turbines, computer room, control rooms, cable

vaults etc. for detecting fire in these places.

4. MOVs & ROVs :-Motor operated vales & Remote operated valves have been provided at criticallocations with facility for remote operation from control rooms. This shall

facilitate prompt & remote closure of valves in case of emergency.

5. Water Sprinklers :-Elaborate water sprinklers and drancher systems have been provided for all critical

storage and vulnerable area. All the Crude tanks have been provided with

dedicated foam pourer system.


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C.RISK ANALYSISA comprehensive Risk Analysis study of Uran On-shore facilities was done by M/s EIL in

1997. The job involved hazard and operability study (HAZOP), HAZAN, Quantitative Risk

Analysis (QRA), Evacuation, Escape and Rescue Analysis (EER).

The following facilities at Uran Complex were included in the scope of work.

GAS PROCESSING

I. Pig receivers & launchers, valve pits.II. Slug catchers & condensate handling units.

III. Gas sweetening units (GSU).IV. Condensate Fractionation Unit (CFU).V. LPG recovery plants.

VI. Ethane-Propane (C2-C3) recovery units (EPRU).VII. Flare and blow-down system.

VIII. Storage and handling of NGL, LPG & C2-C3.OIL PROCESSING

I. Crude Oil inlet lines, valve pits, pig receiver & launcher.II. Crude Stabilization unit (CSU).

III. Surge tank and internal pumping system.IV.

Bulk crude storage and pumping system.

V. Effluent handling system.VI. CSU off-gas compressors.


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CRUDE STABILISATION UNIT

INTRODUCTION:

The Crude Stabilization Unit at Uran, Mumbai is designed to stabilize pressurized crude oilfrom the Mumbai off-shore oil fields. It is designed to produce 20,000,000 tons of stock tank

crude oil per annum. Besides stabilization, the unit includes provision for dehydration and

desalting crude oil whenever required.

PRODUCED WATER

CRUDE OIL

OFF

GAS TO

GSU

TO

ETP

STABILIZED

OIL TO

TROMBAY

CRUDE OILFROM OFF

SHORE

TO ETP

CRUDE

HEATE

2ND STAGE OF

COMPRESSOR

3RD STAGE OF

COMPRESSOR

1ST STAGE OF

COMPRESSOR

LP SEPARATOR

OFF

TO

CRUDE

HEATERCRUDE

EXCHANGERHIGH PRESSURE

SEPERATOR

CRUDE

HEATER

DE-GASER

DE-HYDRATOR

TO

ETP

CRUDE

COOLER

SURGE

TANK

MAIN STORAGE

TANK

OFF GAS


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SOURCE:

The crude oil received from offshore platform is in the unstabilized form. This crude oil

reaches the Uran Plant through 3 oil trunk lines.

The 30" MUT oil pipeline from Mumbai High and 24" HUT oil pipeline from satellite off-

shore platform are the principal feed stock to plant. In addition, provision is kept to process

the slug catcher liquid and reprocessing oil from tank area and recovered oil from the

existing facilities at Uran. Provision is also kept to process the low aromatic naphtha (LAN)

in the LPG recovery units, Condensate Fractionate Units and liquid condensate from

associated gas compressors.

PROCESS DESCRIPTION:

There are five identical trains each consisting of high pressure separator (HP), Dehydrator,

pre-heater and low pressure separator. Each train has a processing capacity of 5 MMTPA.

The Pressurized crude oil received from BUT and HUT oil trunk lines into five streams and

preheated by steam upto 45C before entering into High Pressure Separator V-

201/A/B/C/D/V-601/613 operating at pressure of 3.5 kg/cm^2g.The oil flows out under level

control and can either be directly sent to low pressure separator or can be pumped to the

Dehydrator system. High pressure gas leaves the HP separators under pressure control and is

sent for compression.

Before entering the Dehydrators oil is preheated first by heat exchange with dehydrated oiland then in the crude heaters upto 65C. The Dehydrators remove water and salt from oil. The

dehydration is accomplished by the injection of demulsified, heating or by the application of

high voltage electro-static field in the oil-water emulsion. The dehydrated oil flows under

level control, exchange heat with feed to dehydrator and is then sent to low Pressure

Separators.

The water produced by dehydration is sent to EPTP (Effluent Pre-Treatment Plant) for

predisposal treatment.

The stabilized oil is pumped to five Main Storage Tanks T-202A/B/C/D/E, T-601/A/B/C/D.

The gases from the HP separators, Degassers and LP separators are compressed in the Multi

Service Gas Compressors and sent to LPG unit combining with associated gas from the trunk

line. These are done by 3 stages reciprocating Compressors, operating at suction pressures of

0.05 kg/cm^2g and 14.0 kg/cm^2g. The Degassers are connected to compressors 1 and HP

separator gases are connected to 2 stage suction.


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COMPONENTS:

FEED SUPPLY :The offshore crude oil is received at Uran through 3 oil trunk lines

- 30" BUT oil pipeline (presently isolated).

- 30" MUT oil pipeline.

- 24" HUT oil pipeline.

MUT oil pipelines are provided with three turbine flow meters and one bypass with strainersup streams of interconnection. At CSU end the MUT oil feed line is provided with two out ofthree turbine type flow meters in parallel and the HUT oil feed line is provided one out oftwo turbines types flow meters which measures and integrates flow to the CSU unit. Two

strainers in MUT as well as in HUT oil line have been upstream of flow meters.

HP SEPARATORS:The feed to each High Pressures Separator (HP Separator) is taken from the existing 24"

header through a 16" line with isolation motor operated valve MOV-201/202/203/101/1101, one

shut down valve SDV - 201/202/203/101/1101 and one hand control valve HCV -

201/202/203/101/1101. The feed is heated to 40C before entering the HP separator, in crude

Pre-heater using MP steam.

The HP Separator are three phase horizontal separation vessels, capable of separation oil,free water and gas, having a hold up time of 3 minutes with 50% filling. They are 12.2m long

and has an outer diameter of 2.74m designed for pressure of 5.5 kg/cm^2g and a temperature

of 55C. Each HP Separator is provided with two relief valves, one operating and other on

standby.

The gas from the separator flows on pressure control, through PCV-1010/1020/1030/101/1101 tothe compressors. The produced water flows on interface level control through ILCV-1101/1020/1030/101/1101.The flow of oil from HP Separator is indicated by flow indicators FI-1101/1021/1031/102 /1102.

LP SEPARATORS:The stabilized crude oil from the LP Separator flows by gravity into the Intermediate Surgetanks. These are come roof atmospheric storage tanks of 24m diameter and 12.6m heighthaving a nominal capacity of5000m^3 each. Heating coils are provided in these tanks, withMP steam as the heating medium. The tanks are provided with one low level alarm and onehigh level alarm. The separated gas is continuously vented to safe location through flamearrestor.


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INTERMEDIATE TRANSFER PUMPS :These intermediate Transfer Pumps two operating and one standby, of capacity 750 m^3/hr

and 54m differential head are provided to transfer stabilized crude oil from intermediate

surge tanks to storage tanks. These pumps are provided with emergency power in order to

continue crude stabilizing plant operations even on main power failure. Pumps are provided

with motor operated isolation valves at the suction and discharge.

MAIN STORAGE:Eight main storage tanks each of nominal capacity of 60000m^3 are provided for crude oil

buffer storage. These are floating roof tanks of 79m diameter and 15.6m height. Each tank

except T-601A is provided with mixers in order to prevent settling of sludge. The tanks are

provided with one each level indicators and temperature indicators in control room. They are

also provided with one low level alarm and high level alarms. The tanks are provided with

motor operating isolation valves in the inlet and main outlet lines.

BOOSTER PUMPS AND TRANSFER PUMPS:Two parallel pumping trains (OBPH, NBPH) are providing for pumping requirement of oil.

Old booster pump house pumping train consisting of P-203 A/B/C/D/E/F, take suction from

the main storage tanks and deliver into the 26" crude oil main transfer line. These pumps are

of capacity 750m^3/hr and 54m differential head each. The pumps are provided with motor

operated isolation valves at the suction and discharge. Three crude oil transfer pumps P - 204

A/B/C are connected to above 26" crude oil main transfer line, series arrangement.

In order to take care of increased pumping requirement a new parallel pumping train,

consisting of four Booster Pumps P - 603 A/B/C/D and four transfer pumps P - 604 A/B/C/D

has been added. The crude oil booster pumps take suction outlet from line branching from

existing 36" main storage tank outlet header and deliver into the new 26" crude oil main

transfer line. The pumps are of capacity 500m^3/ hr and 87m differential head each. The

pumps are provided with motor operated isolation valves at the suction and discharge.

CRUDE OIL DISPATCH:Stabilized crude oil is dispatched from the plant to various refineries in India through tankers

from Jawahar Deep (Butcher Island) and BPCL, HPCL refineries at Trombay through

pipeline. In addition to above, facilities are also created for loading and oil through tankers at

JNPT.


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GAS SWEETENING UNIT (G.S.U)

Sweetening of a gas refers to the removal of hydrogen sulphide from the gas. The Gas

Sweetening Plant focuses on the removal of Acid gases, hydrogen sulphide (H2S) and carbon

di oxide (C02) from the feed gas. The feed gas consists of slug catcher Gas, CFU offgas and SUoffgas. The process employed for the separation of the gases is Sulfinol R-D process.

For the sweetening of the sour gas, there are two identical trains. Each of the trains are

designed for a mixed sour gas feed of 5 MMNCM/ day and hence a total capacity of 10

MMNCM/ day. The two trains are operating with a third train used as a standby. Usually only

50% of the designed capacity is used.

LAY OUT DIAGRAM:


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The main two stages in the process are:

1: Inside the absorber column C-1201 the acidic components and the sulphur compounds

present are absorbed from the feed gas at the feed gas pressure level.

2: The Sulfinol solution is regenerated by stripping to remove the absorbed gases from thesolvent in the Regenerated column C-2102 at low pressure and elevated temperature.

- Initially the sour gas is sent to the sour gas knock out drum V-1202 where the contained

liquids are separated and sent to condensate Fractionation Units. Then the gas is fed into the

absorber column where CO2 and H2S are removed by counter current with lean sulfinol

solution to meet the product specification.

The sweet gas from the absorber is sent to sweet gas header via sweet gas knockout drum.

The rich solution from the absorber bottom is flashed into the flash scrubber where it is

scrubbed with the lean solution. The rich solution from this is sent to regenerator column.

The rich solution is regenerated by reboiled vapours generated the attached boiler. The acid

gas which is separated is released into sulphur recovery plant or directly into the atmosphere.


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ETHANE PROPANE RECOVERY UNIT (EPRU):

Ethane and Propane recovery are among the phase-III process in the ONGC Uran Plant,

Uran, and Bombay.

C2-C3 Recovery Unit (EPRU) is supplied with two feed streams from the LPG-I & II Units.

These are the high pressure Second Stage Vapour (SSV) and low pressure feed from the Light

Ends Fractionators (LEF). These streams are partially cooled to condense them. The

refrigeration is provided by passing the high pressure feed streams through an expander and

by a propane refrigeration system. The partially condensed feed streams are fed to the

Demethaniser to separate the methane vapours from C2-C3 liquid. The overhead gas from

the Demethaniser is fed to a second expander to provide cooling to the reflux condenser. The

lean gas is then warmed to ambient temperature by the lean gas Compressors. Refrigeration

gas is provided to LPG I & II as an inter-stage product. The C2-C3 is pumped to Area 16 for

storage as pressurized liquid.

The Ethane Propane Recovery unit can be divided into several subsections:

-SSV Pre-Compression.

- SSV Chill-down.

- SSV Expansion.

- De-methanization.

- Lean Gas Compression.

- Propane Refrigeration.

SSV COMPRESSION:The feed gas is taken to feed gas compressor suction knock-out drum. The gas from knock-

out drum is taken to the compressor of the demethanizer overhead expander compressor.

The compressed gas is directly taken to the suction of the compressor of the feed gasexpander compressor. The compressed gas at 52.5 kg/cm^2g is cooled to 40C & taken to chill

down suction for further chilling.


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SSV CHILLDOWN:The compressed feed gas is then cooled through the heat exchangers from 40C to shunt 25C.

Further feed gas is taken to Demethanizer bottom reboiler where it cooled down to 2.5C.

Then feed gas is taken to Chiller-I & Chiller-II for further chilling when it receives cold by

propane refrigeration & chilled down from 2.5C to- 17C to- 27C to -55C. Then it is fed to

separator-I to separate out condensate. The vapour from separator-I is taken to Chiller-III

where it is chilled further to -67C by exchanger of heat with outgoing cold lean gas. The

partially condensed feed gas at -670C is taken to separator-II to separate out the condensate.

The condensate from separator-I & separator-II is directly fed to Demethanizer column at

tray No.16. The vapour from separator-II at -67C is taken to feed gas expander for expansion.

The LEF vapour received as feed to EPRU is available at 35C is taken to LEF Vapour/ lean gas

exchanger where it is cooled down to 5C. Then it is further chilled down to -7C & -20C at

Chiller-I and Chiller-II respectively by use of propane refrigeration. Then it is taken toDemethanizer side reboiler & chilled down to about -33C. Further it is taken to Chiller-III &

chilled down to -37C & directly taken to Demethanizer column as feed at tray No.27.

SSV EXPANSION:Feed gas, after 2nd stage separation at -67C from separator -II is taken to feed gas expander

compressor for expansion. The majority of the refrigeration need is made available from this

entropic expansion of gas from about 49.6 kg/cm^2g, the gas is further chilled down to about

-100C and is taken directly to Demethanizer column at tray No.10 for fractionation.

DEMETHANIZER:

The function of the Demethanizer column is to recover C2-C3 product from the condensed

liquids at various stages in chill down and expansion sections and remove all undesirable

methane from it. Feed to the column is taken as follows:-

- Feed gas expander outlet (vapour liquid) at tray No.10 at about -100C.

- Mixture of separator-I & separator-II liquid at tray No.16 at about -67C.

- Partially condensate LEF vapour at tray No.25 or tray No.27 at about -37C.

- Of-spec C2-C3 product, if any, storage at tray No.40.

The vapour from Demethanizer reflux drum is taken to Demethanizer overhead expander

compressor, where it is expanded to about 14 kg/cm^2g. Due to this expansion, gas is further


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chilled down to about -111C. This cold methane rich vapour is utilized for refrigeration then it

is taken to lean gas compressor.

LEAN GAS COMPRESSION:

After the recovery of Ethane and Propane, the lean gas is received in the lean gas compressorknock-out drum at about 20C & 12.7 kg/cm^2g. Then lean gas is compressed to about 40

kg/cm^2g by lean gas compressor. The compressor gas after cooling to about 40C is supplied

at battery limit for gas consumers.

LEF ON

VAPOURS

LEAN

SSV

FEED PRE COMPRESSION OF FEED

THROUGH EXPANDER

DRIVEN COMPRESSORS

1ST STAGE

CHILL

DOWN

1ST STAGE

VAPOUR

LIQUID

1ST STAGE

VAPOURS TO

2ND STAGE

1ST STAGE

VAPOURS

LIQUID

SEPARATI

2ND STAGE

VAPOURS

LIQUID

SEPARATI

DEMETHAISE

COLUMN

CHILL DOWN BY

PROPANE

FEED TO

DEMETHANIS

ER COLUMN

LEF O/H

VAPOURS

C2C3PRO


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PROPANE REFRIGERATION SYSTEM:

To supplement the refrigeration requirement, EPRU is provided with Propane Refrigeration

System. The feed gas is chilled down upto -67C with the help of propane refrigeration system

followed by further heat exchange.

BASIC PRINCIPLES:

There are two basic principles for LPG recovery from natural gas. They are

1. REFRIGERATION

2. FRACTIONATION

REFRIGERATION:

1. By using the relation between temperature and pressure a refrigeration system is designed.

2. A refrigerant is a fluid which picks up heat from process system, by boiling at low

temperature and pressure which is done by compressor.

In LPG plant propane is used as refrigeration and it picks up heat from feed gas.

FRACTIONATION:

Fractionation is a unit operation in which a multi-component liquid mixture is separated

into individual components with condensate purity.

It is a continuous process of vaporization and condensation and there by separation of pure

individual components is achieved.

Relatively more vaporization takes place for lighter component and more condensation takes

place for heavier component.

A continuous heat input is given through reboiler at the bottom to accomplish stripping of

the feed.

An external reflux is given form the top of the column through the reflux drum to cool andwash the top vapours so that the pure components with maximum recovery can be achieved.


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Turbo-Expander of Uran

Turbo-expander is a centrifugal turbine through which a high pressure gas is expanded to

produce work that is often used to drive a compressor. Turbo-expanders are widely used in

cryogenic and energy recovery applications. These machines operate under extremeconditions of high speed, high pressures and very low temperatures. But at the same time,

due to the above reasons, problems encountered in these machines are very unique in

nature.

PROCESS FLOW DIAGRAM

Shaft

Gas InGas Out

CONSUMER LEAN GAS

EXPANDER DRIVEN

COMPRESSORFEED GAS

COOLER E-1501

FEED GAS

Gas outGas in

Compressor

Expander

Compressor

Wheel

Expander

Wheel

LIQUID ETHANE-

PROPANE TO

STORAGE PIPES

DEMETHANIZERCOLUMN

CHILLING

SECTION

EXPANDER


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CONDENSATE FRACTIONATING UNIT (CFU-1):

The CFU has been designed and constructed for the stripping pf acid components, H2S and

CO2, from the condensate mainly supplied from slug catcher (Phase II and Phase III) and IHI

& HP compressors; in addition, the condensate is intermittently supplied from K.O. druminstalled in Gas Sweetening Unit (GSU).

CFU is composed of the following sections:

- Feed condensate treatment section.

- Condensate stripping section.

- Off gas compressor section.

- Flare section.

PROCESS:

The condensate from the slug catcher, CSU, LPG and GSU act as the feed to the

Condensation Fractionation Unit. The feed enters the feed coalescer (X-1101) operating at 48-

52 kg/cm^2g where water is removed and the condensate is fed to the stripper column (C-

1101). The Stripper column operates at 23-25 kg/cm^2g and here the H2S and CO2 gases are

removed. This stripped vapour goes to the knock out drum (K.O.D V-1101). The heat

requirement to the stripper column is given by the stripper bottom re boiler (E-1101). The

stripper bottom liquid is supplied to the re boiler via stripper bottom pump and filter (X-1102). The vapour generated in the re boiler is returned to the stripped for stripping and the

stripping liquid in the re boiler is sent to the stripper bottom re boiler surge drum. The

stripped liquid can be sent as a reflux to stripper Column or sent to CFU-II or LPG column.

The stripped vapour containing H2S and CO2 is sent to the reciprocating type gas

compressor where the gas pressure is built up to available sour gas U/S pressure. The

compressed gas goes to the cooler and then to the off-gas compressor discharge K.O.D and

from the gas is sent to GSU.

DESCRIPTION:

- FEED SUPPLY:

The feed to the condensate Fractionating Unit (CFU-II) is the condensate at 63t/h which is

obtained as follows:

- 30.5 t/h slug catcher condensate corresponding to 8-9 MMNM3/ day pipeline gas.


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- 16.0 t/h compressor 3rd stage condensate for 20 MMTPA crude processing (with HSVR

modification.)

The slug catcher condensate is pumped from the surge drum located near the slug catcher by

transfer pumps through filter and a flow control valve. Any free water present in the

condensate will separate out in the drum and collect in the water boot. The condensate

under level cascaded with flow control will be pumped to CFU-II by CSU second stage

condensate transfer pumps. The pump is provided to give sufficient head to avoid any

hydrocarbon flashing in the feed coalesce. In case the condensate is received at a pressure

greater than 50 kg/ cm^2g an no flashing is reported, provision has kept to bypass the

transfer pumps and take the condensate directly to feed coalescer.

-H2S STRIPPER:

Feed to the H2S stripper is a mixture of liquid and vapour. The column has 60 valve trays.The top section has single pass trays (5 trays) and the bottom has double pass trays (55 trays).

A dry tray and a demister has been provided at column top to remove any liquid entrained

along with the vapour. The Stripper bottom liquid is pumped through bottom filter pumps to

re boiler through filters. The heat supply to the re boiler is from the MP Steam. provision has

been kept to divert the bottom product from the re boiler to the LPG columns of LPG-I and

LPG-II in case LPG column of CFU-II is shut down.

-LPG COLUMN:

The bottom liquid from both the CFU-I and CFU-II stripper is taken to LPG column on the21st tray, provision is also there to put the feed on the 16th tray. This column has 50 valve

trays and is designed to separate LPG (propane and butane) from heavier components. The

column operates at a pressure of 10 kg/cm^2. The pressure is maintained by a hot vapour

bypass type control scheme. The column bottom temperature is maintained at 153.5C and the

column top is maintained at 70C using medium pressure steam. LPG is taken as overhead

liquid product through LPG reflux and transfer pumps.

-CONDENSATE OFF-GAS COMPRESSION:

The stripper overhead vapour is taken to off gas compressor suction K.O. drum. The surgedrum flashed vapour if any is also combined with this stream before it enters the suction

K.O. drum. Two reciprocating compressors are provided to compress this sour gas to enable

it to flow to the gas sweetening units. The compressed gas is cooled to 45C in discharge

cooler which uses cooling water on shell side. The cooled gas flows to gas sweetening unit via

compressor discharge K.O. Drum. The condensate formed flows under level control to

stripper column.


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CO-GENERATION (COGEN)

INTRODUCTION:

Cogeneration means simultaneous generation both electrical and thermal energy byraising a single primary heat source, thereby increasing the overall efficiency of the plant.

Cogeneration is one of the most powerful and effective energy conservation techniques. In

industries like refineries, petrochemical, fertilizer, sugar etc, there is a requirement of both

power and steam. LPG/CSU plant at Uran needs power and steam. To meet this requirement a

cogeneration plant was setup. Hence this plant fulfills the requirement of both electrical power

and steam at a very low cost and high efficiency and reliability.

Cogeneration is of two types namely

Copping up cycle

Bottom up cycleCopping cycle is one of in which heat requirement is attained by externally firing the

fuel. Whereas in bottom up cycle the heat requirement is fulfilled by internal chemical reactions

this cycle is used in medicine production.

Cogeneration plant at ONGC Uran is based on copping up cycle. The principle of this

plant is mentioned below:

PRINCIPLE:

Air from atmosphere is taken through an air filter and compressed in axial flow

compressor driven by the turbine. The compressor air enters into combustion chamber where it

is mixed with fuel (lean gas). During combustion its temperature increases at constant pressure

(process B to C) then it expands mechanical energy by rotating the turbine. A major part of this

energy is available for the generator. Hence the thermal efficiency of the generator is very low.

Diesel engine is used for initial cranking of the system. Once the turbine attains the speed the

contact is broken. However only 30% of the compressed air is used for combustion and energy

conversion and the rest of the air is used for cooling and sealing of the net bas path (Turbine

blades nozzles etc). The efficiency of the turbine can be increased if the metallurgical part of thenozzle and blades are improved so that the size of the compressor can be reduced for the same

turbine.


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Layout Diagram of the C0-Generation Plant

Exhaust flue gases from the turbine has got sufficient heat energy (512C at full load),

is passed through a vertical water tube boiler duct converting heat energy into useful steam.

These boilers are known as HRSG (Heat recovery steam generator). This steam is used for

LPG/CUS process plant. The amount of steam which is generated in this condition requiresZero or very small fuel input (if supplementary firing is dine to increase the steam

production), so the overall efficiency of the plant is increased.

Heat recovery ste

generator

19

Supplementary

Firing Fuel [9 MW]

By pass

Duct

Burner

Compressor

[17 STAGES]

[AXIAL

Air Filter

Combustion

Chamber

Fuel

Starting Diesel

Engine

Air filter

Turbine

Gear box

Alternator

3000 RPMFuel

HRSG

Air [40 C]

Hot Gas


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Power capacity of the gas turbine (GT):

Power- 3*19.6 MW

GE frame- 5 gas turbines

Steam capacity of the waste heat recovery boilers (HRSG):

Steam- 2*75+1*90 TON/HR

Waste heat recovery boilers

Plant demand for power and steam:

Power average - 41.0 MW/HR

Power (peak) - 50.0 MW/HR

Steam - 150 TON/HR

Export (with 3 GTS) - 5.0 MW/HR

Import (with 3 GTS) - NIL

This power and steam demand is easily met by the Co-generation plant as the power

turbines produce 3*19.6 MW= 58.8 MW.

The steam produced by the HRSG is 2*75+1*90 TON/HR = 240 TON/HR

But sometimes one of the gas turbine may not be operational as mechanical failure

may occur, fuel gas line may leak, seizure of the compressor of the turbine etc. The Co-

generation plant is always connected to the power grid MSEB in the case of failure of one of

the turbines. Thus undisturbed power supply continues.


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EFFLUENT TREATMENT PLANT: (MINAS)

LAYOUT OF MINAS PLANT

EFFLUENTFROM CSU

EFFLUENT PRE-TREATMENT

(EPTP)SURGE POND CPI SEPERATOR

SAND FILTER

BIO-TOWER I CLARIFIER BIO-TOWER II

CLARIFIER II GUARD PONDDISPOSAL

PUMP

POLYELECTROLYTE

DOSING UNIT

EFFLUENT FROM

OTHER SOURCES

EFFLUENT FROM

TANK FARM

Discharge to seathrough closed

conduit disposal

system

RECYCLE

PUMPS


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Effluent received from CSU is routed back to EPTP, where oil & water are separated using

gravity separation. Oil is sent back to CSU & water is further routed to surge pond where it

gets mixed with effluents of other plants like LPG, GSU, and EPRU. This effluent is sent to

ETP (MINAS) Plant for further treatment before final discharge into sea through close

conduit disposal system. The process description ofETP (MINAS) having a capacity of350M3 /Hrs (dry weather) and 700M3/Hrs (wet weather) is as given below.

Pre-weather treatment by gravity separation using corrugated plate interceptors (CPI)to reduce gross separable oil contamination.

Primary treatment by sand filtration with in line polyelectrolyte addition to removesuspended solids and flocculated oil.

Secondary treatment using biological filtration with random packed plastic media asthe substrate for the biomass. Di-ammonium phosphate addition in upstream of Bio-

towers. Secondary treatment is meant for removing soluble pollutants (BOD).

Tertiary treatment is provided in the form of conventional gravity clarifications toremove any humus sludge from Bio-tower effluent.

Polishing of treated effluent by means of sub surface aerators in the guard pond. Disposal by pumping through closed conduit disposal system to low tide level into the

sea.


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SLUG CATCHER

Bombay high gas is transported from offshore platforms to Uran Terminal via 26

subsea lines about 210 km length BUT lines and the length of 26 gas pipelines from Satellite

field to offshore be about 91 km (HUT line). The operational flexibility of diverting BombayHigh gas to Heera is provided through ICP-Heera Trunk Line and also through SHS-Heera

Trunk line. A total combined (BUT & HUT) 16.5 MMSCM/D of gas handling facilities has

been created at Uran Terminal in the Slug-Catcher Unit of which 11.3 MMSCM/D gas

processing capacities has been created at GSU. LPG and ethane-propane recovery units to

extract value added products like LPG/LAN/C2-C3 and the remaining rich gas will be sent

through plant bypass loop to consumer, GAIL for extracting value added products at their

LPG recovery plant USAR and to the fertilizer unit of RCF and power sectors.

There are two Slug Catchers provided in two phases (Phase-II and Phase-III), to

handle sweet gas coming from BH field and sour gas from Satellite fields to knock out the

condensate from the incoming gas before gas processing and diverting the gas consumers.

Slug catcher facilities are to serve the following objectives:

To separate the continuously coming condensate from the saturated gas by reducingof the fluid velocity and subsequent gravity separation.

To hold the slug fluid coming at Uran at the time of pigging of gas pipe lines. To continuously send the hydrocarbon liquid to CFU-1 /2 units for further processing. To partially stabilize the liquid from phase 2 sweet liquid condensate and inject into

crude inlet to CSU in case of CFU-1/2 are down. To supply gas (after condensate separation) to GSU-12/13 plants. The formation of condensate is due to pressure reduction from 90 kg/cm to 50

kg/cm. The retrograde condensation taking place and accumulation of liquid at the

low points of sea-bed.

Capacity of slug catcher

Phase 2:

o Design capacity : 8 mm nm/dayo Volume : 3100 m(this hold up is for 2 days)o Sea bed temp : 20C minimumPhase-3:

o Design capacity : 5mm nm/dayo Volume : 450 m(this holds up for 2 days)


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Process Description:

Gas from offshore coming to Uran terminalby 26 submarine gas pipeline shall enter

the expanded slug catcher. In case of balanced gas supply from offshore to consumer, the

offshore gas straightaway enters the slug catcher but if there is an excess of gas from offshore

compared to consumption, the offshore gas enters the slug catcher through a pressure

control valve to maintain normal operating pressure at GSU Inlet. In such cases excess gas, if

desired =, can be routed to Hazira from the offshore itself. From slug catcher the separated

gas takes its normal route to GSU.

The liquid slug catcher sump flows into a slug liquid drum where gas & liquid can take

two routes. Either it can be pumped via filters to CFU I/II or LPG II liquid driers for further

processing in CFU I/II or it can be partially stabilized in slug liquid stabilizer after heating in

Slug Heater. The flashed gases go to flare while partially stabilized condensate is routed to

CSU I/II. This route becomes necessary when either CFU I or II or both units are down andare not in position to accept condensate and during pigging operation of gas trunk lines.


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LPG-1

LPG recovery unit:

Two units of 5.65 MMSCMD capacities each receives the sweet gas from GSU.

The combined capacities of LPG units are as follows:-

Sweet gas throughput: 11.3 MMSCMD

LPG production: 3, 17,000 MTPA

LAN production: 1, 87,000 MTPA

LPG-1 Capacity:

Design:

Feed-sweet gas: 5.65 MMSCMD

Product

LPG: 1, 58.500 MTPA

LAN: 93,500 MTPA

In case of GSU and EPRU Shutdown LPG plant can directly run on sour gas(the gas from slug

catcher).

Product components of natural gas:

Methane No. of carbon atoms 1 Lean gas to consumers

Ethane 2 C2-c3 to IPCL for furtherprocessing

Propane 3 LPG at 8kg/cm2 to BPCL

& HPCLButane 4Pentane 5 Naphtha to IOTL for

further dispatchHexane+- 6 To petrochemical plants

Basic principles:

LPG recover from natural Gas is made on the two principles:

Refrigeration


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FractionationRefrigeration:

By using the relation between temperature and a pressure a refrigeration system designed. A refrigerant is a fluid which picks up heat from process system, by boiling at low temp and

pressure and gives up heat by condensing at a high temperature and pressure which is done

by compressor.

In LPG plant propane is used as Refrigerant and it picks up the heat from feed gas.

Fractionation:

Fractionation is a unit operation in which a multi-component liquid mixture is separated intoindividual components with considerable purity.

It is a continuous process of vaporization and condensation and there by separation of a pureindividual component is achieved.

Relatively more vaporization takes place for lighter component and more condensation takesplace for heavier component.

A continuous heat input is given through re-boiler at the bottom to accomplish stripping ofthe feed.

An external reflux is given from the top of the column through the reflux drum to cool and,wash the top vapors, so that a pure component with maximum recovery can be achieved.

There are 3 columns used in LPG-1 plant.

LEF & LPG columns:Separated liquid from V-103 & V-104 passed through E-103, E-101, and E-118 and sent

to LEF column at around 20oC to remove the lighter fractions which mainly contain C2-

C3. The gas coming out from the top of the column goes to reflex drum V-105 after

getting cooled in E-105. Liquid is knocked out from V-105 and remaining gas called LEF

Top is sent to C2-C3 recovery unit. The bottom liquid goes to LPG column. If C2-C3

recovery unit is under shut down LEF top can be sent to consumer line after compressing

through residue gas compressor K-102A/B. The liquid from LEF column enters either 9th

or 12th

or 15th

tray of LPG column. The top product of column is propane and butane

(called LPG or Liquefied petroleum Gas) and the bottom product is called Naphtha

(LAN-Light Aromatic Naphtha).

Propane column:The propane is used as a refrigerant in the refrigeration system. The propane losses which

occur during refrigeration of feed gas require make-up. Therefore a propane column is

designed in LPG plant to recover propane taking the LPG as a feed to the column. It

consists of 37 trays and LPG as feed enters 25th

tray. Propane product is withdrawn from

5th

tray as side out product to remove the lighter impurities.


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RUSTON GAS TURBINE (RGT)

Gas based LPG Extraction Plant is based on cryogenic process. The purpose of cooling of

feed gas accomplished by heat exchange with refrigerant, liquid propane. The liquid propane, in

turn, vaporizes after gaining heat in the exchange process. A centrifugal compressor compresses thispropane vapour for liquefaction to complete the refrigeration cycle. The drive to propane compressor

Ebara is a Gas Turbine, supplied by Ruston, U.K. the turbine is coupled to the compressor by a

compressor by a gear box at its power turbine end.

LPG-2

Process Description:

Sweetened gas from GSU flows to knock out drum where any liquid present is

separated out, and then the gas is pre cooled to 250oC. The pre cooled gas is sent to knockout drum

where Liquefied hydrocarbon and water are separated out. The gas then flows to the molecular sieve

drier where the moisture is reduced to less than 4 ppm level. The dried gas is cooled to -220 degree

C in the first stage chiller; condensed liquid is separated out. Vapor is further cooled to -370 degree

C and condensed liquid is again separated out. Remaining non-condensate gas called SSV is sent to

C2-C3 plant. Cooling of gas is achieved by exchanging heat against external refrigeration. External

refrigeration is supplied in three stages at -70 C, -270 C & -400 C.

The SSV (second stage vapor) after separation of liquid condensate are delivered as

feed stock to C22-C3 recovery unit, alternatively the SSV can be delivered to consumer trunk line if

C2-C3 unit is under shut down.

A propane column is provided in LPG-I to recover liquid propane from LPG streams. Propane is

used as refrigerant for LPG-I & II, C2 C3 plant to maintain desired operating temperatures. Propane

column will be in service intermittently as per requirement to make up refrigerant losses. For

external refrigeration propane compressor K-501 is driven by electric motor with constant speed.

For the operation point of view, the entire plant may be divided into following subsection:

o Feed gas supply/ pre-coolingo Feed gas dryingo Feed gas chill downo Light ends fractionate column(LEF)o LPG columno Refrigeration systemo Fuel gas systemo Flare and blow down system


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o Methanol system

Startup procedure:

The various steps leading to a safe and smooth start-up of LPG unit are as follows:

o Purging the unito Refrigeration of molecular sieveo Drying of the unito Commissioning of Methanol systemo Charging and establishing refrigeration cycleo Establishing flow through chill down sectiono Commissioning of light ends fractionatorso Commissioning of LPG columno Stabilizing the unit

LPG PRODUCT

CONDENSATE

FROM CFU-I

NGL/NAPTHA

SSV TO EPRU

DRYERS FILTERS REFRIGERATION

UNIT

SEPERATORSFRACTIONATING

COLUMN

LEF O/HTO EPRU


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Propane Recovery Unit:

Propane is produced from LPG in LPG-1 plant. Propane column (10C-103) takes LPG feed from the

discharge of LPG reflux pump of LPG-1 plant/ LPG-2 plant. The column operates at about 15

kg/cm2 top-pressure and about 85 degree Celsius bottom and 40C top temperature. Its top product

is propane and bottom which is butane goes to LPG spheres.

This is a small column and intended to meet the internal requirement of propane, which

is used as refrigerant in LPG and C2-C3 plants.

Flare System:

In case of process upset gas is flared through two numbers of elevated flares for lighter hydrocarbon

and one box flare forheavier hydrocarbon, which are kept alive with the help of purge gas for safety.

If needed, low temperature liquids are diverted to blow down drums, where it is converted into gas

with help of low-pressure steam and then diverted to the flare header. Condensate formed, if any, is

collected in flare knockout drum and pumped back to process unit.

Propane columnLPG

FUEL GAS

PROPANE TO

STORAGE

To LPG Storage


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Study of Compressor:

Agas 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 cantransport 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.

o Types of compressor

Fig: Different types of compressors
http://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Pipe_(material)http://en.wikipedia.org/wiki/Pipe_(material)http://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Pumphttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Pressure


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Centrifugal compressorCentrifugal compressors, sometimes termed radial compressors, are a sub-class of

dynamic axisymmetric work-absorbing turbo machinery.

Fig: Inner look of centrifugal compressor

The idealized compressive dynamic turbo-machine achieves a pressure rise by adding kineticenergy/velocityto a continuous flow offluid through the rotor or impeller. This kineticenergy is then converted to an increase in potential energy/static pressure by slowing

the flow through a diffuser.Imagine a simple case where flow passes through a straight pipe to enter centrifugalcompressor. The simple flow is straight, uniform and has no swirl. As the flow continues topass into and through the centrifugal impeller, the impeller forces the flow to spin faster andfaster. According to a form of Euler's fluid dynamics equation, known as "pump and turbineequation," the energy input to the fluid is proportional to the flow's local spinning velocitymultiplied by the local impeller tangential velocity. In many cases the flow leavingcentrifugal impeller is near or above 1000 ft./s or approximately 300 m/s. It is at this point, inthe simple case according to Bernoulli's principle, where the flow passes into the stationarydiffuser for the purpose of converting this velocity energy into pressure energy.

Components of centrifugal compressorA simple centrifugal compressor has four components:

Inlet Impeller/rotor Diffuser Collector
http://en.wikipedia.org/wiki/Turbomachineryhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Impellerhttp://en.wikipedia.org/wiki/Potential_energyhttp://en.wikipedia.org/wiki/Fluid_dynamicshttp://en.wikipedia.org/wiki/Euler%27s_pump_and_turbine_equationhttp://en.wikipedia.org/wiki/Euler%27s_pump_and_turbine_equationhttp://en.wikipedia.org/wiki/Bernoulli%27s_principlehttp://en.wikipedia.org/wiki/File:Compressor_wheel_Napier_NA357.JPGhttp://en.wikipedia.org/wiki/Bernoulli%27s_principlehttp://en.wikipedia.org/wiki/Euler%27s_pump_and_turbine_equationhttp://en.wikipedia.org/wiki/Euler%27s_pump_and_turbine_equationhttp://en.wikipedia.org/wiki/Fluid_dynamicshttp://en.wikipedia.org/wiki/Potential_energyhttp://en.wikipedia.org/wiki/Impellerhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Turbomachinery


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Inlet:The inlet to a centrifugal compressor is typically a simple pipe. It may include

features such as a valve, stationary vanes/airfoils (used to help swirl the flow) and

both pressure and temperature instrumentation. All of these additional devices have

important uses in the control of the centrifugal compressor.

Centrifugal impeller:The key component that makes a compressor centrifugal is the centrifugal

impeller; it is the impeller's rotating set of vanes (or blades) that gradually raises the

energy of the working gas. This is identical to an axial compressor with the exception

that the gases can reach higher velocities and energy levels through the impeller's

increasing radius. In many modern high-efficiency centrifugal compressors the gas

exiting the impeller is traveling near the speed of sound.Impellers are designed in many configurations including "open" (visible

blades), "covered or shrouded", "with splitters" (every other inducer removed) and

"w/o splitters" (all full blades).

Fig: centrifugal Impeller

Diffuser:The next key component to the simple centrifugal compressor is the

diffuser. Downstream of the impeller in the flow path, it is the diffuser's responsibility

to convert the kinetic energy (high velocity) of the gas into pressure by gradually

slowing (diffusing) the gas velocity. Diffusers can be vaneless, vaned or an alternating

combination.


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.

Fig: Diffuser

High efficiency vaned diffusers are also designed over a wide range of solidities fromless than 1 to over 4. Hybrid versions of vaned diffusers include: wedge, channel, andpipe diffusers. There are turbocharger applications that benefit by incorporating nodiffuser.

Bernoulli's fluid dynamic principal plays an important role in understandingdiffuser performance.

Collector:The collector of a centrifugal compressor can take many shapes and forms. When the

diffuser discharges into a large empty chamber, the collector may be termed

a Plenum. When the diffuser discharges into a device that looks somewhat like a snail

shell, bull's horn or a French horn, the collector is likely to be termed

a volute or scroll.

As the name implies, a collectors purpose is to gather the flow from the diffuser

discharge annulus and deliver this flow to a downstream pipe. Either the collector or
http://en.wikipedia.org/wiki/Bernoulli%27s_principlehttp://en.wikipedia.org/wiki/Bernoulli%27s_principle


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the pipe may also contain valves and instrumentation to control the compressor. For

example, a turbocharger blow-off valve.

Working

Centrifugal compressors use the rotating action of an impeller wheel to exertcentrifugal force on refrigerant inside a round chamber (volute). Refrigerant is sucked

into the impeller wheel through a large circular intake and flows between the

impeller. The impellers force the refrigerant outward, exerting centrifugal force on the

refrigerant. The Refrigerant is pressurized as it is forced against the sides of the volute.

Centrifugal compressors are well suited to compressing large volumes of refrigerant to

relatively low pressures. The compressive force generated by an impeller wheel is

small, so chillers that use centrifugal compressors usually employ more than one

impeller wheel, arranged in series. Centrifugal compressors are desirable for their

simple design and few moving parts.

Applications In gas turbines and auxiliary power units.

In their simple form, modern gas turbines operate on the Brayton cycle. Either

or both axial and centrifugal compressors are used to provide compression. The types

of gas turbines that most often include centrifugal compressors include turbo shaft,

turboprop, auxiliary power units, and micro-turbines. The industry standards applied

to all of the centrifugal compressors used in aircraft applications are set by the FAA

and the military to maximize both safety and durability under severe conditions.

In automotive engine and diesel engine turbochargers and superchargers.Centrifugal compressors used in conjunction with reciprocating internal

combustion engines are known as turbochargers if driven by the engines exhaust gas

and turbo-superchargers if mechanically driven by the engine. Standards set by the

industry for turbochargers may have been established bySAE. Ideal gas properties

often work well for the design, test and analysis of turbocharger centrifugal

compressor performance.

In pipeline compressors ofnatural gas to move the gas from the production site to theconsumer.

Centrifugal compressors for such uses may be one- or multi-stage and driven by large

gas turbines. Standards set by the industry (ANSI/API, ASME) result in large thick

casings to maximize safety. The impellers are often if not always of the covered style

which makes them look much like pump impellers. This type of compressor is also
http://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Turbochargerhttp://en.wikipedia.org/wiki/SAEhttp://en.wikipedia.org/wiki/Pipeline_transporthttp://en.wikipedia.org/wiki/Natural_gashttp://en.wikipedia.org/wiki/Natural_gashttp://en.wikipedia.org/wiki/Pipeline_transporthttp://en.wikipedia.org/wiki/SAEhttp://en.wikipedia.org/wiki/Turbochargerhttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Gas_turbine


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often termed an API-style. The power needed to drive these compressors is most often

in the thousands of horsepower (HP). Use of real gas properties is needed to properly

design, test and analyze the performance of natural gas pipeline centrifugal

compressors.

In oil refineries, natural gas processing, petrochemical and chemical plants.Centrifugal compressors for such uses are often one-shaft multi-stage and

driven by large steam or gas turbines. Their casings are often termed horizontally

split or barrel. Standards set by the industry (ANSI/API, ASME) for these compressors

result in large thick casings to maximize safety. The impellers are often if not always

of the covered style which makes them look much like pump impellers. This type of

compressor is also often termed API-style. The power needed to drive these

compressors is most often in the thousands of HP. Use of real gas properties is neededto properly design, test and analyze their performance.

Air-conditioning and refrigeration and HVAC: Centrifugal compressors quite oftensupply the compression in water chillers cycles.

Because of the wide variety of vapor compression cycles (thermodynamic

cycle, thermodynamics) and the wide variety of workings gases (refrigerants),

centrifugal compressors are used in a wide range of sizes and configurations. Use of

real gas properties is needed to properly design, test and analyze the performance of

these machines. Standards set by the industry for these compressors include ASHRAE,ASME & API.

Reciprocating compressorAreciprocating compressor or piston compressor is a positive-displacement

compressor that uses pistons driven by a crankshaft to deliver gases at high pressure.

The intake gas enters the suction manifold, then flows into the compression cylinder where itgets compressed by a piston driven in a reciprocating motion via a crankshaft, and is then

discharged. Applications include oil refineries, gas pipelines, chemical plants, natural gas

processing plants and refrigeration plants. One specialty application is the blowing of plastic

bottles made ofPolyethylene Terephthalate (PET).
http://en.wikipedia.org/wiki/Oil_refinerieshttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Petrochemicalhttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Air-conditioninghttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Vapor-compression_refrigerationhttp://en.wikipedia.org/wiki/Thermodynamic_cyclehttp://en.wikipedia.org/wiki/Thermodynamic_cyclehttp://en.wikipedia.org/wiki/Thermodynamicshttp://en.wikipedia.org/wiki/Refrigeranthttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Oil_refineryhttp://en.wikipedia.org/wiki/Pipeline_transporthttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/Polyethylene_Terephthalatehttp://en.wikipedia.org/wiki/Polyethylene_Terephthalatehttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Pipeline_transporthttp://en.wikipedia.org/wiki/Oil_refineryhttp://en.wikipedia.org/wiki/Crankshafthttp://en.wikipedia.org/wiki/Pistonhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Refrigeranthttp://en.wikipedia.org/wiki/Thermodynamicshttp://en.wikipedia.org/wiki/Thermodynamic_cyclehttp://en.wikipedia.org/wiki/Thermodynamic_cyclehttp://en.wikipedia.org/wiki/Vapor-compression_refrigerationhttp://en.wikipedia.org/wiki/HVAChttp://en.wikipedia.org/wiki/Refrigerationhttp://en.wikipedia.org/wiki/Air-conditioninghttp://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Petrochemicalhttp://en.wikipedia.org/wiki/Natural_gas_processinghttp://en.wikipedia.org/wiki/Oil_refineries


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Fig: Reciprocating compressor function

Fig: Amotor-driven six-cylinder reciprocating compressor that can operate with two,

four or six cylinders.

Applications:

Reciprocating compressors utilize crankshaft driven pistons to compress gases for usein various processes. Much like internal combustion engines, an offset crankshaft

causes rotary motion of a piston rod which is converted to linear motion via a

crosshead. The crosshead can only move in a linear motion so that the rotary motion

of the crankshaft is transformed into linear motion of the piston. As the piston moves

to and fro, it takes in low pressure gas and increases its pressure. Unlike an internal

combustion engine, the gas is not ignited. It is allowed to leave the compressorcylinder at a higher level of pressure than when it went in.

The majority of applications for reciprocating compressors are in the oil and gasindustries. Oil refineries use these compressors for processes that require high

pressure delivery of essential gases. The natural gas industry also utilizes reciprocating

compressors to transport gas via cross country pipelines. These compressors can also

be found in chemical plants, refrigeration plants, air compressors for tooling, etc.


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Reciprocating compressors are unique pieces of equipment as they contain activecomponents that are moving in rotary as well as linear directions. They also play a

vital role in any process that they are employed in. Therefore, a reciprocating

compressors health must be monitored, but in order to do so, you must do more than

follow the usual vibration monitoring rules.

Axial Compressor:Axial compressors are rotating, airfoil-based compressors in which the working

fluid principally flows parallel to the axis of rotation. This is in contrast with other

rotating compressors such as centrifugal, axis-centrifugal and mixed-flow compressors

where the air may enter axially but will have a significant radial component on exit.

Axial flow compressors produce a continuous flow of compressed gas, and havethe benefits of high efficiencies and large mass flow capacity, particularly in relation to

their cross-section. They do, however, require several rows of airfoils to achieve large

pressure rises making them complex and expensive relative to other designs

(e.g. centrifugal compressor).

Axial compressors are widely used in gas turbines, such as jet engines, high

speed ship engines, and small scale power stations. They are also used in industrial

applications such as large volume air separation plants, blast furnace air, fluid

catalytic cracking air, and propane dehydrogenation. Axial compressors, known

as superchargers, have also been used to boost the power of automotive reciprocatingengines by compressing the intake air, though these are very rare.

Fig: Axial flow compressor
http://en.wikipedia.org/wiki/Airfoilhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Centrifugal_compressorhttp://en.wikipedia.org/wiki/Gas_turbineshttp://en.wikipedia.org/wiki/Jet_enginehttp://en.wikipedia.org/wiki/Superchargerhttp://en.wikipedia.org/wiki/Superchargerhttp://en.wikipedia.org/wiki/Jet_enginehttp://en.wikipedia.org/wiki/Gas_turbineshttp://en.wikipedia.org/wiki/Centrifugal_compressorhttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Airfoil


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Working:A compressor in which the fluid enters and leaves in the axial direction is

called axial flow compressor. So, the centrifugal component in the energy equation

does not come into play. Here the compression is fully based on diffusing action of the

passages. The main parts include a stationary (stator) part and a moving (rotor) part.The diffusing action in stator converts absolute kinetic head of the fluid into rise in

pressure. The relative kinetic head in the energy equation is a term that exists only

because of the rotation of the rotor. The rotor reduces the relative kinetic head of the

fluid and adds it to the absolute kinetic head of the fluid i.e., the impact of the rotor

on the fluid particles increases its velocity (absolute) and thereby reduces the relative

velocity between the fluid and the rotor. In short, the rotor increases the absolute

velocity of the fluid and the stator converts this into pressure rise. Designing the rotor

passage with a diffusing capability can produce a pressure rise in addition to its

normal functioning. This produces greater pressure rise per stage which constitutes astator and a rotor together. This is the reaction principle in turbo-machines. If 50% of

the pressure rise in a stage is obtained at the rotor section, it is said to have a 50%

reaction.

Rotary screw compressor:A rotary screw compressor is a type ofgas compressorwhich uses a rotary type

positive displacement mechanism. They are commonly used to replace piston

compressorswhere large volumes of high pressure air are needed, either for largeindustrial applications or to operate high-power air tools such as jackhammers.

The gas compression process of a rotary screw is a continuous sweeping

motion, so there is very little pulsation or surging of flow, as occurs with piston

compressors.

Operation:Rotary screw compressors use two meshing helical screws, known as rotors, to

compress the gas. In a dry running rotary screw compressor, timing gears ensure that

the male and female rotors maintain precise alignment. In an oil-flooded rotary screwcompressor, lubricating oil bridges the space between the rotors, both providing a

hydraulic seal and transferring mechanical energy between the driving and driven

rotor. Gas enters at the suction side and moves through the threads as the screws

rotate. The meshing rotors force the gas through the compressor, and the gas exits at

the end of the screws.
http://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Piston_compressorhttp://en.wikipedia.org/wiki/Piston_compressorhttp://en.wikipedia.org/wiki/Jackhammerhttp://en.wikipedia.org/wiki/Jackhammerhttp://en.wikipedia.org/wiki/Piston_compressorhttp://en.wikipedia.org/wiki/Piston_compressorhttp://en.wikipedia.org/wiki/Gas_compressor


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Fig: Rotary screw compressor

The effectiveness of this mechanism is dependent on precisely fitting clearances

between the helical rotors, and between the rotors and the chamber for sealing of the

compression cavities.


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Gas turbineAgas turbine, also called a combustion turbine, is a type ofinternal

combustion engine. It has an upstream rotating compressor coupled to a

downstream turbine, and a combustion chamber in-between.Energyis added to the gas stream in the combustor, where fuel is mixed

with air and ignited. In the high pressure environment of the combustor, combustion

of the fuel increases the temperature. The products of the combustion are forced into

the turbine section. There, the high velocityand volume of the gas flow is directed

through a nozzle over the turbine's blades, spinning the turbine which powers the

compressor and, for some turbines, drives their mechanical output. The energy given

up to the turbine comes from the reduction in the temperature and pressure of the

exhaust gas.

Energy can be extracted in the form of shaft power, compressed air or thrust or

any combination of these and used to power aircraft, trains, ships, generators, or

even tanks.

Fig: A typical axial-flow gas turbine turbojet
http://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Turbinehttp://en.wikipedia.org/wiki/Combustion_chamberhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Combustorhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Ignition_systemhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Nozzlehttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Trainhttp://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Tankhttp://en.wikipedia.org/wiki/Tankhttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Trainhttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Nozzlehttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Ignition_systemhttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Combustorhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Combustion_chamberhttp://en.wikipedia.org/wiki/Turbinehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_engine


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Operation:Gases passing through an ideal gas turbine have three thermodynamic processes.

These are isentropic compression, isobaric (constant pressure) combustion and

isentropic expansion. Together these make up the Brayton cycle.

In a practical gas turbine, gases are first accelerated in either a centrifugal or

axial compressor. These gases are then slowed using a diverging nozzle known asa diffuser; these processes increase the pressure and temperature of the flow. In an

ideal system this is isentropic. However, in practice energy is lost to heat, due to

friction and turbulence.

Fig: Brayton Cycle
http://en.wikipedia.org/wiki/Thermodynamicshttp://en.wikipedia.org/wiki/Isentropichttp://en.wikipedia.org/wiki/Isobaric_processhttp://en.wikipedia.org/wiki/Brayton_cyclehttp://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Diffuser_(automotive)http://en.wikipedia.org/wiki/Diffuser_(automotive)http://en.wikipedia.org/wiki/Gas_compressorhttp://en.wikipedia.org/wiki/Brayton_cyclehttp://en.wikipedia.org/wiki/Isobaric_processhttp://en.wikipedia.org/wiki/Isentropichttp://en.wikipedia.org/wiki/Thermodynamics


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Gases then pass from the diffuser to a combustion chamber, or similar device,

where heat is added. In an ideal system this occurs at constant pressure (isobaric heat

addition). As there is no change in pressure the specific of the gases increases. In

practical situations this process is usually accompanied by a slight loss in pressure,

due to friction. Finally, this larger volume of gases is expanded and accelerated bynozzle guide vanes before energy is extracted by a turbine. In an ideal system these

are gases expanded isentropically and leave the turbine at their original pressure. In

practice this process is not isentropic as energy is once again lost to friction and

turbulence.
http://en.wikipedia.org/wiki/Combustorhttp://en.wikipedia.org/wiki/Turbinehttp://en.wikipedia.org/wiki/Turbinehttp://en.wikipedia.org/wiki/Combustor


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INTRODUCTION TO HEAT EXCHANGER:Heat exchanger is equipment, which effects the transfer of heat from one fluid to

another.

Types of heat exchanger:

Based on heat transfer process Based on service Based on construction Based on Flow Arrangements

Types based on Heat Transfer Process Direct Contact Type Fluids are not separated.

Example is Cooling Tower

Indirect Contact Type Fluid Streams separated by an impervious wall Examples are Tubular Exchangers, Plate Heat Exchangers

Types of Exchangers Based on ServiceHeater:

It is a unit that exchanges heat between two process streams without phase change; i.e.liquids are neither evaporated nor condensed.

Cooler:

Cools the process fluids without phase change.Condenser:

Condenses process vapour stream. Examples: Some of the Fin fan Cooler

Re-boiler:

Provides latent heat of vaporization to bottom of distillation / fractionation column.Pre-heater:


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Uses steam or hot process stream to heat & or vaporize the feed to processing unit. Types of Exchangers Based on Construction:

Tubular heat exchanger: U tube type heat exchanger Fixed tube sheet heat exchanger Floating head type heat exchanger Pipe in pipe heat exchanger Fin fan type exchanger Plate type heat exchanger Spiral plate type heat exchanger

Types of Exchangers Based on Flow Arrangements Co-current flow Both Fluid Streams flow in same direction High Thermal Stresses at inlet as large variation in inlet temp. of two streams Least effective Counter-current flow Fluids flow in opposite directions True counter current flow not easily achievable Cross Flow Fluids flow normal to each other Shell and Tube Heat Exchangers

Fig: Shell and Tube Heat Exchanger


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Functions of S&T exchangers

Heating ( gas or liquid) Cooling without condensing ( gas or liquid) Condensing of vapors ( partial condensing OR full condensing) Evaporating liquid (partial or full)Basic Components of S&T Exchangers

Tubes Provides the heat transfer area Bare Tubes or Finned Tubes Seamless or welded

Tube sheets Holds the tubes in place Tubes expanded or welded on the tube-sheets

Tube Side Nozzles & Channel Controls the flow of the tube side fluid Normally of same material as that of tube & tube-sheet or are cladded. Channel Covers Round plates bolted to the Channels and can be removed for tube side inspection

Shell & Shell Side Nozzles Shell is a container for shell side fluid Shell side nozzles are inlet and outlet for shell side fluid. Shell is normally circular in cross section. Shell is made by rolling of plates or of pipes (upto 24 inch dia)

Impingement plate Provided at shell inlet nozzle to avoid impact of fluid on the top row of the tubesBasic Components of S&T Exchangers

Pass Partition Plate Provided in channel or bonnet for increasing the no. of tube passes


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Baffles Provide support to the tubes during assembly and operation and prevent vibration ofthe tubes.

Guide the shell side fluid flow resulting in increased turbulence and heat transfercoefficient

For liquid flows baffle cut is approx 20 to 25% of shell dia For gaseous flow baffle cut is 40 to 45% of shell dia Refrigerant, compressor, expansion valve (flow control device), evaporator, condenser, pipes

and tubes.

COMPRESSION REFRIGERATION SYSTEM

Schematic of Compression Refrigeration System


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EXPLANATION OF HOW IT WORKS/ IS USED:

Refrigerant flows through the compressor, which raises the pressure of the refrigerant. Nextthe refrigerant flows through the condenser, where it condenses from vapor form to liquid

form, giving off heat in the process. The heat given off is what makes the condenser "hot to

the touch." After the condenser, the refrigerant goes through the expansion valve, where it

experiences a pressure drop. Finally, the refrigerant goes to the evaporator. The refrigerant

draws heat from the evaporator which causes the refrigerant to vaporize. The evaporator

draws heat from the region that is to be cooled. The vaporized refrigerant goes back to the

compressor to restart the cycle.

COMPONENT:

Compressor:Of the reciprocating, rotary, and centrifugal compressors, the most popular among

domestic or smaller power commercial refrigeration is the reciprocating. The reciprocatingcompressor is similar to an automobile engine. A piston is driven by a motor to "suck in" and

compress the refrigerant in a cylinder. As the piston moves down into the cylinder

(increasing the volume of the cylinder), it "sucks" the refrigerant from the evaporator. The

intake valve closes when the refrigerant pressure inside the cylinder reaches that of the

pressure in the evaporator. When the piston hits the point of maximum downard

displacement, it compresses the refrigerant on the upstroke. The refrigerant is pushed through

the exhaust valve into the condenser. Both the intake and exhaust valves are designed so that

the flow of the refrigerant only travels in one direction through the system.

Diagram of Compressor (Belt Driven In This Instance)


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Detail of Compressor Valve Function

Components of Compression

Refrigeration In A Dorm

Refrigerator

Condenser:The condenser removes heat given off during the liquefaction of

vaporized refrigerant. Heat is given off as the temperature drops to

condensation temperature. Then, more heat (specifically the latentheat of condensation) is released as the refrigerant liquefies. There

are air-cooled and water-cooled condensers, named for their

condensing medium. The more popular is the air-cooled condenser.

The condensers consist of tubes with external fins. The refrigerant

is forced through the condenser. In order to remove as much heat as

possible, the tubes are arranged to maximize surface area. Fans are

often used to increase air flow by forcing air over the surfaces, thus

increasing the condenser capability to give off heat.

Evaporator:This is the part of the refrigeration system that is doing the actual cooling. Because its function is

to absorb heat into the refrigeration system (from where you don't want it), the evaporator is

placed in the area to be cooled. The refrigerant is let into and measured by a flow control device,


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and eventually released to the compressor. The evaporator consists of finned tubes, which

absorbs heat from the air blown through a coil by a fan. Fins and tubes are made of metals with

high thermal conductivity to maximize heat transfer. The refrigerant vaporizes from the heat it

absorbs heat in the evaporator.

Flow control device (expansion valve):This controls the flow of the liquid refrigerant into the evaporator. Control devices usually are

thermostatic, meaning that they are responsive to the temperature of the refrigerant.

a visit to uran plant of ongc

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