2. Primarilycomposed ofmethane,the NATURAL GAS 1. Natural gas is worlds cleanest fossil fuel....

2. Primarily composed of methane, the

NATURAL GAS

1. Natural gas is worlds cleanest fossil fuel.

lightest of the hydrocarbon compounds..

3. Because of its high- energy value and itslow emission of carbon dioxide (CO2) andnitrogen oxides (NOx) when burned, ithas become the fuel of choice for newelectric power plants and many newindustrial facilities.

1.Natural gas is found in undergroundrock formations known as reservoirs.

2.The reservoir rock is typically a poroussand, sandstone, limestone ordolomite.

NATURAL GAS SOURCES

3.The gas in the reservoir may be mixedwith oil, or the reservoir may containonly natural gas and natural gasliquids, commonly referred to ascondensate.

1.As production begins from a reservoir, gas,oil or condensate and water are producedsimultaneously.

2.Production equipment located at the surfaceseparates each of the fluids.

NATURAL GAS--PRODUCTION

3.The oil and condensate can be stored inaboveground tanks or pumped into apipeline.

4.The water is collected for disposal, and thegas can be compressed into a pipeline or re-injected into the reservoir to maintainreservoir pressure.

1. Natural gas is colorless.

2. While delivering the gas as a fuel for household,Local gas utilities add mercaptan for safetypurposes-since it allows small leaks at lowpressures in the distribution systems to be easilydetected.

NATURAL GAS--PROPERTIES

3. The specific gravity of natural gas is about 0.67.

4. The heating value of natural gas is approximately8900 kcal/ per standard cubic meter. However, itdepends upon the actual composition of the gas.

Since naturalgas is primarilymethane it is ahigh-energy,clean-burning

NATURAL GAS--PROPERTIES

fuel. This qualityis clearlyillustrated in thegraph to theright comparingemissions fromnatural gas, fueloil and coal.

JHABUA

HVJ PIPELINE

UTTAR PRADESH

DADRI

BABRALA

SHAHJAHANPUR

JAGDISHPURAURAIYA

GAIL PATA

BARODA

VAGHODIA

HAZIRA

KALOL

SOUTH BASSEIN

BOMBAY HIGHHEERA

VIJAIPUR

KHERA MADHYAPRADESH

MAHARASHTRA

MUMBAIURAN

THAL

GUJARATKADI

HARYANA

DELHI

RAJASTHAN

KOTA

ANTA

1. Crude oil and natural gas are of little use in their raw state;their value lies in what is created from them: fuels,lubricating oils, waxes, asphalt, petrochemicals and pipelinequality natural gas.

NATURAL GAS PROCESSING

2. On an energy equivalent basis, Natural gas liquids (C2+)generally have a greater economic value as a raw materialfor petrochemicals and motor gasoline compared to theirvalue as a component in natural gas.

3. Natural gas from the well, while principally methane,contains quantities of other hydrocarbons - ethane,propane, butane, pentane and also carbon dioxide andwater. These components are separated from the methaneat a gas fractionation plant.

extract natural gas liquids from natural gas after fractionationwhere the mixed hydrocarbon liquid are separated into thepurity NGL products of ethane, propane, normal butane,isobutane and natural gasoline.

NATURAL GAS PROCESSINGNatural gas when produced at the wellhead, may containcontaminants such as water, carbon dioxide, nitrogen andhydrogen sulfide.. Commercial natural gas is principally methaneand, to a lesser extent, ethane. Natural gas processing plants

USE OF NATURAL GASIndustries use natural gas to provide energy for variousmanufacturing processes. Natural gas is also being usedas a transportation fuel.Compressed natural gas or CNG: Used in car and vanfleets.Three important components are obtained from naturalgas: ethane, propane, and butane.Ethane: Raw material in the petrochemical industry.Ethane is processed to make ethylene that is used tomanufacture polyethylene.

Ethylene is used to manufacture following:• ethylene glycol or anti-freeze for radiators.Ethylene oxide. vinyl chloride, polyvinyl chloride orPVC.

• Raw material to manufacture vinyl acetate forpaints and adhesives. Polystyrene manufacturedfrom ethylene is used to make resins for rubber.

• Ethanol is also produced from ethylene..

1. Propane and butane are used to manufacture the chemicalbuilding blocks: propylene and butylene.

2. Propylene oxide produced from propylene is used to sterilizemedical and food products and to manufacture surfactants.Propylene glycol, is used as industrial antifreeze and ashydraulic and brake fluid.

3. Butylene is an important chemical used in manufacturing

USES OF NATURAL GAS

products that improve the quality of gasoline.

4. Natural gas is a raw material to make ammonia foragricultural fertilizer.

5. Carbon black, which is used to reinforce rubber and makeink and batteries, comes from natural gas.

6. Paints use lamp black formed from natural gas for tinting.

USES OF LPGDOMESTIC USE: FOR HOUSEHOLD COOKING

INDUSTRIAL USE

•AIR HEATING

•BOILER FIRING

•ASPHALT MELTING

•CARBON BLACK APPLICATIONS

•DESALINATION OF SEA WATER

•RUBBER PRODUCTS CURING

•PAPER PRODUCTS DRYING

•PAINT DRYING

•PORTABLE FLOOD LIGHT ILLUMINATING

•INCINERATORS

• AS A HIGH CALORIFIC VALUE FUEL IN DIFFERENT INDUSTRIES

• AS AN AUTOMOTIVE FUEL

• BLENDED WITH BUTANE FOR PRODUCTION OF LPG

• FEEDSTOCK FOR POLYPROPYLENE & PROPYLENE GLYCOL

USES OF PENTANE

USES OF PROPANE

• Pentane is used as solvents. as an additive in automotive andaviation fuels.

• Raw material for the production of chlorinated pentanes andpentanols.

• It is used in artificial ice manufacture, low--temperaturethermometers, solvent extraction processes, blowing agentin plastic, etc.

USES OF NAPHTHA

• Naphtha is sold to large consumers in Power (NTPC

etc.) & Fertilizer Sectors.

NATURAL GAS PROCESSING PLANTS IN GAIL

• GAIL (INDIA) LTD has LPG recovery plant at Vijaipur,Vaghodia, Usar, Pata, Gandhar & Lakwa.

• LPG is recovered from Natural Gas by expansion,chilling & fractionation after dehydration of naturalgas.

• LPG RECOVERY PLANT PATA is integrated with GasProcessing Unit of UPPC Pata. C2+ liquidhydrocarbon produced in GPU is sent to LPG plant forproduction of C2/C3, Propane, LPG, Pentane &Naphtha.

• The main processes involved in LPG plants are• Feed gas drying/regeneration• Feed gas expansion by using expander• Feed gas chilling.• Separation• Fractionation for separation of products.

Component Typical Analysis(mole %)

Methane 79.50

Ethane 10.0

Propane 3.4

Butane 1.2

Pentane 0.25

Hexanes plus 0.1

Carbon Dioxide 5.5

Nitrogen 0.05

Specific Gravity 0.70

TYPICAL NATURAL GAS COMPOSTIONAT GAIL PATA

GASSWEETENINGUNIT

C2/C3RECOVERYUNIT

FROM HBJ PIPELINE

12.66 MMSCMD

BLOCK DIAGRAM OFGAIL, PATA

CO2 TO ATMOSPHERE

NATURAL GASGAS

CRACKERUNIT

TPA : TONNES PER ANNUM

ETHYLENE

LPGETHANE / PROPANE

RECOVERY

400,800 TPA

UNIT

71,085 TPA PROPANE

LEAN NATURAL GAS BACK TO HBJ

NAPHTHA + PENTANE

258,250 TPA LPG

LLDPE+HDPE

LLDPE:160,000TPAHDPE:200,000TPA

LEGENDMMSCMD : MILLION STANDARD CUBIC METRES PER DAY

FEED:DEMETHANISER BOTTOM LIQUID FROM GPU(12.66 MMSCMD OF NATURAL GASPROCESSING )

PRODUCTS:LPGC2/C3PROPANENAPHTHAPENTANE

2,58,250 TPA4,00,080 TPA71,085 TPA26,742 TPA19,755 TPA

GAS

PROCESS FLOW DIAGRAM12.66MMSCMD

11.35 MMSCMDSWEET GAS

SWEETENING UNITRich Gas from

GAIL Vijaipur(HVJ P/L)

LPGUNIT

LPG 258,250 TPAPropane 71,000 TPA

C2+RECOVERY

UNITGAS CRACKER UNIT

9.3MMSCMD

Lean Gas backto HVJ pipeline

C2/C3

400,800 TPA

Pentane/ Naphtha 46497 TPA

TPA : Tonnes per Annum

MMSCMD : Million Standard Cum. Mtrs. Per Day

GAS SWEETENING UNIT

Feed GasFrom HVJ

12.66 MMSCMD

(CO2: ~5 Mole %) (CO2 : < 50PPM)

CO2 : ~ around 1000 TPD

Sweet Gas

GasSweetening

Unit

AB

SO

RB

ER

S

WATERWASHCOLN.

Sweet gas toC2+

RecoveryUnit

CO2

Naturalgas

FILTER-COASLESCER

PROCESS FLOW DIAGRAM OF GAS SWEETENING UNIT

AmineFiltrationPackage

Lean/RichExch.

Flash Drum tank

LeanAmineCooler.

Coolingwater

K.O.DVV-001

Reflux.

drum

Amine

GAS SWEETENING UNITBrief Process Description :

Receiving sour feed gas from HVJ pipeline afterfiltration & pressure reduction.

Counter-current Absorption of CO2 from feed gas byDow Speciality amine CS plus in Absorbers at 50Kg/cm2.

Flashing of Rich Amine from 50 Kg/cm2 to 5.5Kg/cm2 to remove the dissolved hydrocarbons

Preheating of Rich Amine to 100 deg C utilizing theheat of regenerated lean amine and subsequently,desorption of CO2 in Regenerator column by heatingthe amine to 120-123 deg C using LP Steam inreboilers.

GAS SWEETENING UNITBrief Process Description :

Heat Exchange between lean amine & rich amine andCooling of lean amine to 48-52 deg C using coolingwater.

Storage & recycling of lean amine to Absorbers.

Water-washing of sweet gas (containing less than 50ppm of CO2) to remove entrained amine.

Side stream filtration of lean amine using cellulosepre-coat filter and charcoal filters.

Problem Effect of the problemFrequent failure of theregenerator reboiler tubes.

The shell side of the reboilers arehigh temperature and two-phaseflow region. The earlier tubebundles were made of CS whichwere used for cooling DEAsolution which was corrosive innature

Frequent plant shutdown

GAS SWEETENING UNITProblems experienced:-

Problem Effect of the problemInsufficient cooling from theamine coolers.

Earlier, there were 03 noscoolers as per original design (2working in parallel + 1 standby).Required cooling was notobtained due to improperdistribution of amine in thecoolers

High lean amine temperatureleading to poor absorption


Problem Effect of the problemCorrosion in earlier aminesystem.

DEA was being used earlier.Being corrosive in nature, it hadcaused depletion of the corrosionallowances in the pipelines,especially at the bends & elbows.

Reduction in thickness ofpipelines & elbows. High ironcontent in recirculating amine

High foaming tendency

This was due to the presence ofimpurities such as dust particles,oil-mists etc in the sour feed gaswhich was carried over to theabsorbers and mixed up with thecirculating amine

Restriction of plant load due tohigh pressure drop across theabsorbers on account offoaming

Degradation of amine


Problem Effect of the problemSevere corrosion of regeneratortop trays

The top trays of the regeneratorcolumn were badly corroded dueto high concentration of acidgases at the region which wasfurther aggravated due tocorrosive nature of DEA usedearlier

Inefficient mass transfer in thetop trays of the column leading tohigh LP steam consumption inreboilers

High pressure drop in absorbers

The valve trays inside theabsorbers put higher restrictionagainst the gas flow, causinghigh pressure drop across theabsorbers

Restriction of plant load


Measures Benefits

Provision for putting aminecoolers in series as well as inparallel.

This has ensured properdistribution of amine in the aminecoolers leading to more effectiveheat transfer. Also, one additionalamine cooler installed whichresults into additional surfacearea available for heat transfer.

Effective reduction in lean aminetemperature.

GAS SWEETENING UNITMeasures adopted to counter the problems:-

Measures Benefits

Replacement of CS tube bundleof the reboilers with SS 316Ltube bundle.

This has effectively counteredthe corrosion & tube leakageproblem for the reboilersresulting into no further tubeleakage.

Elimination of plant downtime onaccount of tube leakage of thereboilers


Measures Benefits

Complete changeover of solventto Dow Speciality Amine CSplus.

This is basically a tertiary aminewhich is less corrosive in nature.This speciality amine alsocontains activator such aspiprazine etc. which increasesthe reactivity of the amine withthe acidic components presentin the sour feed gas

Elimination of corrosion problem

Lower regeneration temperature


Measures Benefits

Installation of additional charcoalfilters having higher capacity formore effective removal of iron &HC.

Earlier, there was only onecharcoal filter of smaller sizethrough which the amine flow rate

thwas maintained as 1/100 part ofthe re-circulating amine flow rate.In order to enhance the capacity ofthe charcoal filter, 02 nos newfilters were installed in parallel tothe old one and thus the totalcapacity of the charcoal filters

thhave increased to 1/10 part of re-circulating amine flow rate.

Reduced foaming tendency

Reduced iron & HC content


Measures Benefits

Installation of Filter-Coalescer atthe U/s of absorbers.

This had been installed torestrict the carryover of oil-mists/heavier HC along with thesour feed gas to the absorberswhich had led to foaming

Effective separation of oil-mists/HC droplets from the feed gasleading to reduction in foaming

Replacement of top 11 nos traysof the regenerator with SS 316Lvalve trays.

This had replaced the badlycorroded trays at the upper sideof the column which were madeof SS 304.

Reduced corrosion of trays

Effective mass transfer at theupper part of the column wherethe concentration of acid gas isvery high.


Measures Benefits

Replacement of valve trays ofthe absorbers with high capacitySS 316L Nye trays.

This had been done toovercome the problem of highpressure drop (around 0.5Kg/cm2) across the valve trayswhich was restricting the gasflow. The Nye trays are havingfixed opening for gas flowthrough the same leading of lowpressure drop (around 0.28Kg/cm2) and thus higher gashandling capacity.

Reduced pressure drop

Increased gas throughput


Earlier status Present status

Amine carried over along with thesweet gas was drained out fromthe d/s vessels of the water washcolumn

Carried over amine is reclaimed andrecycled back to amine systemthrough Amine filtration system

The residual amine inside thecellulose pre-coat filter wasdrained during replacement ofcellulose pre-coat

The residual amine is taken into theamine system by rinsing the pre-coat filter with condensate waterbefore discarding the old pre-coat

For routine analysis, sample ofamine was taken thrice a day. Theamine for sample line purging wasbeing drained.

The sample line purging is beingdone in closed system and theamine is taken back into the system

GAS SWEETENING UNITAdditional Measures adopted to increase plant performances:-

Benefits:-Saving of Rs 90 Lakhs per annum on account of saving of 32 MT ofamine per year.Positive impact on environment due to reduction in amine loss


The CO2 loading in rich amine wasearlier maintained as 0.38 mol ofCO2 per mol of amine. Average LPsteam consumption was 1.98 MTper MT of CO2 removed.

The CO2 loading in rich amineincreased to 0.42 mol of CO2 permol of amine by reducing leanamine flow rate to absorbers. As aresult, average LP steamconsumption is reduced to 1.85MT per MT of CO2 removed.


Benefits:-

The benefit is Rs 3 crores per annum on account of reduction inLP steam consumption


The cellulose pre-coat of thecellulose pre-coat filter ofamine filtration system wasreplaced every week in aroutine manner.

The same is now beingreplaced once in a monthdepending upon the actualperformance of the cellulosepre-coat filter which isreflected by the pressure dropacross the filter.


Benefits:-Cellulose consumption is reduced by 800 Kg per yearPositive impact on environment due to reduction in cellulosedisposal from amine filtration system

from GSU11.35 MMSCMD(CO2:< 50 PPM)

C2+ RECOVERY UNIT

Lean Gas : 9.4 MMSCMD

Sweet Gas

C2+RECOVERY

UNIT

Feed Stock for LPGplant.

EE 007A/B

EE 035

PROCESS FLOW DIAGRAM OF C2+ RECOVERY UNIT

PROPYLENE

VV 002A/B

DRYER

EP 006

KE 001COMP

KE 002

VV 001

LEAN GASCOMPRESSOR

VV015

EP 007

EP 001

COMPRESSOR

EP 003

EP 002 EE 019 SEP 3

SEP 1EP 005

KE 001EXP

CC 001

LEAN GASEP 004KE-002

EE 015

SEP 2

AA

CC 001

CC 002

C2/C3 COLUMNIN LPG

PRODUCT

EXPANDER

C2+ RECOVERY UNITBrief Process Description :

Compression of sweet gas to 55 Kg/cm2 followed bytemperature reduction to 18 deg C using propylenerefrigeration.

Drying of sweet gas to the dew point of -100 deg C &subsequent filtration of dried sweet gas.

Stage-wise chilling of sweet gas through a series ofplate-heat exchangers with intermediate separation ofliquid HC from gas.

Expansion of gas from 50 Kg/cm2 to 22 Kg/cm2through turbo-expander resulting into temperaturereduction to -90 deg C.

Separation of methane from the liquid HC inDemethaniser column.

C2+ RECOVERY UNITBrief Process Description :

Expansion of Demethaniser column O/H vapor from20 Kg/cm2 to 10 Kg/cm2 resulting into furtherreduction in temperature to -117 deg C.

Heat exchange between sweet feed gas and lean gasin plate heat exchangers.

Pre-compression of lean gas to 12 Kg/cm2 usingenergy of gas expansion.

Further compression of lean gas to 50-55 Kg/cm2using Gas turbine driven centrifugal compressors forputting it back into the HVJ pipeline.

Problem Effect of the problemHigh pressure drop across EP-004.

This was due to frequent hydrateformation inside the core of EP-04

Restriction of plant load; Frequentderimings (once in every month)to bring down the pressure drop

High pressure drop across feedgas filters at the D/s of the Dryers.

The filter elements for the earlierdryers were of monel metal andthe pores of the same werefrequently blocked by thecarryover of molecular sieve dustfrom the Dyers.

Restriction of plant load

Frequent cleaning of filterelements

C2+ RECOVERY UNITProblems experienced:-

Problem Effect of the problemPoor reboiling in EP-005.

This was due to higher pressuredrop against the flow of liquid

thfrom the 24 tray of theDemethaniser to EP-05 onaccount of zig-zag routing of theline.

Restriction of plant load and highmethane content in Demethaniserbottom product

Poor reboiling in EP-006.

This was mainly due to thecombined effect of presence ofheavier HC at the bottom ofDemethaniser and insufficientsurface area for EP-06

Restriction of plant load and highmethane content in Demethaniserbottom product


Problem Effect of the problemMalfunctioning of important tripswitches.

In past, the important trip switcheshad actuated on false reasons onseveral instances causing plant trip

Frequent plant tripping

High pressure drop across EP-001.

EP-01 was used to exchange heatbetween lean gas at subzerotemperature and sweet gassaturated with moisture. As aresult, the exchanger wasexperiencing high pressure dropacross its sweet gas side onaccount of hydrate/ice formation

Restriction of plant load.

Failure of EP-001


Measures BenefitsIntroduction of Dryer purgingsystem before putting inadsorption cycle.

By adopting this procedure, theresidual regeneration gas insidethe regenerated Dryer is flushedout with fresh sweet gas in orderto remove all the oil-mists etc fromthe Dryer bed which is carried overby the regeneration gas and whichmay cause hydrate formation atthe plate heat exchangersespecially in EP-04. The purgedgas is put into lean gas headerwithout any wastage.

Reduction in deriming frequencyof EP-04 from once in a month toonce in a year.

C2+ RECOVERY UNITMeasures adopted to counter the problems:-

Measures BenefitsDepressurization and blowing ofEP-004 done in the backwarddirection i.e from the Reflux drumto Demethaniser during deriming.

This ensures blowing of theexchanger in backward directionwhich effectively removes thehydrates & its nucleus from thecore of EP-04

Reduction in pressure dropacross EP-04

Reduction in derimingfrequency of EP-04 from oncein a month to once in a year.


Measures BenefitsIntroduction of hold-on grating atthe bottom and distributor plate atthe top for the dryer bed.

This ensures even distribution offeed gas across the entire Dryerbed reducing the possibility ofchanneling of gas. This alsoensures retention of Dryer bedabove the moisture basket at thebottom of the Dryer.

Even distribution of gas acrossthe Dryer bed leading to improvedperformance of the Dryer


Measures BenefitsChangeover of molecular sievefrom IPCL make to UOP make.

The dust formation from the UOPmake molecular sieve is quite lessthan the earlier IPCL make.

Reduced pressure drop acrossfilter

Increased plant throughput

Installation of new feed gas filter ofhigher capacity in parallel with theold filters.

The new filter is having non-moneltype filter elements and is ofhigher capacity


Measures BenefitsThe inlet and outlet lines of EP-005(Demethaniser side reboiler) werererouted with minimum bends &turns.

This results in less pressure drop inthe line from Demethaniser column toEP-05 due to straightening of the line

Improved reboiling in EP-05 &EP-06

Improved efficiency ofDemethaniser column

thThe height of the chimney tray (24 )of Demethaniser was increased inorder to increase hydraulic headacting on EP-005.

Installation of additional core for EP-06 (Demethaniser Bottom reboiler) inorder to enhance the surface area forheat transfer.


Measures BenefitsInstallation of EE-035 (PropyleneRefrigeration exchanger) after failureof EP-01.

This acts as the permanentreplacement of EP-01 which coolsthe sweet gas to 18 deg C at the U/sof Dryer.

Cooling of sweet gas before Dryeras a permanent substitute for EP-01

Installation of EE-007 (Plate heatexchanger) after failure of EP-01.

Heat exchange between feed gasafter Dryer and Lean gas inabsence of EP-01


Measures BenefitsInstallation of new moistureseparator (VV-002B) in parallel tothe existing one (VV-002A).

This ensures reduction of gasvelocity through the moistureseparators leading to effectiveremoval of free moisture

More effective removal of freemoisture at the U/s of the Dryers

Installation of Prestripper Column.

The heavier HC condensed inSeparator-III is diverted to thiscolumn. The bottom product fromthe column is directly sent to theC2/C3 column bypassingDemethaniser.

Reduction of liquid load onDemethaniser column


Measures BenefitsInstallation of Filter-separator inthe feed gas line at Gas receivingterminal.

This ensures removal of all foreignparticles from the feed gas at theGas terminal itself which is theentry point for the feed gas forGAIL, Pata

More effective separation offoreign particles from sour feedgas at the gas receiving point

Introduction of 2 out of 3 voterlogic for all the trip switches.

This ensures that plant will not tripon account of malfunctioning/falseactuation of any trip switch. It willtrip only if any genuine reasonexists for tripping of the plant

Elimination of frequent plant tripon account of malfunctioning oftrip switches

Enhanced operational reliability



The LG compressors weretripped every time onactuation of plant trip.

The trip logic is modified so that onactuation plant trip, the LGcompressors will keep on running atminimum governing speed withantisurge valves in full opencondition.

As a result, the plant load is restored3-4 hrs earlier due to saving of thestart up time for the LGCs

C2+ RECOVERY UNITAdditional Measures adopted to increase plant performances:-

Benefits:-

Saving of Rs. 60 lakhs for saving of each tripping of LGCMinimization of thermal stress on Gas Turbines on account offrequent tripping


The ventilation fans of GasTurbines were drawing highcurrent (140-145 amps againstF.L.C of 148 amps) with the inletdamper of the fans opened by 15-20% only leading to insufficient airflow inside the GT enclosure.

The fans used to trip veryfrequently on overload

The pulleys of the fan and themotor were interchanged so thatthe r.p.m of the fans werereduced

As a result, the current drawn bythe fans reduced to 80-90 ampsonly.

The inlet damper of the fans arenow being opened fully resultinginto sufficient air flow inside theGas Turbine enclosure


Benefits:-

Saving of Rs 20 lakhs per annum on account of reducedenergy consumption by the fans.


Flare & Blowdownheaders of GPU werekept under positivepressure using fuel gasas end purge.

Nitrogen is being used atpresent for this purposein place of fuel gas.


Benefits:-

Saving of Rs 28 Lakhs per annum on account ofsaving of fuel gas.


The feed gas Dryers aredesigned for 12 hrs adsorptioncycle.

As a result, there were 02 nosof regenerations every day.

The adsorption cycle time forthe Dryers are increased to 24hrs depending on the actualperformance of the Dryers.

As a result, there is only 01 noregeneration every day leadingto the saving of Fuel gasrequired for 01 no regeneration(5200 SCM per day).


Benefits:-

Saving of Rs 3.08 crores per annum on account ofreduction in fuel gas consumption.

Modification Benefit

Satellite dosing for the coolingwater system for amine coolers

Reduced pressure drop andtherefore, reduced frequency ofdismantling & cleaning of aminecoolers.

Conversion of relay based tripsystem to the PLC based systemfor LG Compressors and RGCompressor

Easy identification of reason oftripping and quick remedial actions

Installation of LEL detectors in theGas Terminal area

Improved safety in that location

Some other important modifications in GPU

Modification Benefit

Installation of 3” line for supplyingfuel gas to Gas Turbines directlyfrom the lean gas header in caseof GPU trip

Sustained running of Gas Turbinesin case of GPU trip

Replacement of old feed gasfilters at Dryer D/s with new onehaving higher capacity

To cater for the requirement of astandby filter to the existing new filterat higher plant load (14 MMSCMD)

Installation of temperature controlvalve in the condensate lineleading to Desuperheater

Better controlling of condensate flowto the Desuperheater ensuring exactsaturation of LP steam to reboilers

Some other important modifications in GPU

Modification Intended benefitImplementation of automaticblowdown control system for HeatRecovery & Steam Generationsystems

Reduction in energy and waterconsumption due to reduction incontinuous blow down (CBD) fromsteam drums

Conversion of amine pump triplogics from relay based to PLCbased system

Easy and instant identification ofreason of tripping, resulting intoearly resumption of plant

Changeover of MOC of aminelines, valves, control valves, MOVsfrom CS to SS316L with increase inpipeline diameter

Reduced corrosion & erosion andenhanced amine flow rate at higherplant load (14 MMSCMD)

Some future modifications in GPU

LPG UNIT

C2+ Feed fromDemethanisercolumn

LPG

PRODUCTS– C2/C3– PROPANE– LPG–

PENTANE

–

NAPHTHA

Brief Process Description:

•

•

Fractionation in four distillation columns.

Propylene Refrigeration for C2C3 Column and various heat-exchangers for GPU.

C2/C3 Propane LPGPentane

SteamTurbine

C3RCompr

PropyleneRefrigeration

PROCESS FLOW DIAGRAM OF LPG UNIT

C2/C3Column

Naphtha

PropaneColumn

NGLColumn

LPGColumn

C2+ feed fromDemethaniser

09-V

V-0

21

09-V

V-0

20

09-V

V-0

19

09-V

V-0

18

TURBINEDRIVE

09-KA-003

PROPYLENE REFRIGERATION SYSTEM

VHP STEAMB/L

STEAM

MP STEAM

LP STEAMC.W.

SURFACE CONDENSER

COND.PUMP

B/L

TO C2/C3 CONDENSER

FROM C2/C3 CONDENSER

MAKE UP REFRIGERANTB/L

08-EE-019 08-EE-015

T 68.4P 17.3

T 40

P 16.9

09-VV-017

T 13P 8.7

T –7.0P 4.8

T –28.0P 2.3

T –41P 1.4

FROM EE-035

TO EE-035

LPG UNITBrief Process Description :

The bottom product of Demethaniser columncontaining C2+ hydrocarbons is fed into C2/C3column

C2/C3 column separates C2/C3 (a mixture of 85% C2& 15% C3) as the top product. The necessary chillingis provided in the O/H condenser through propylenerefrigeration

The bottom product of C2/C3 column is fed intoPropane column which separates pure C3 as topproduct.

The bottom product of Propane column is fed intoLPG column which separates LPG as top product.

LPG UNIT

Brief Process Description :

The bottom product of LPG column is fed into NGLcolumn which separates pure C5 as top product andNaphtha as bottom product.

All the products are sent to their respective storages.

Propylene refrigeration is provided by the PropyleneCompressor which is a steam turbine driven four-stage centrifugal compressor consisting of apropylene accumulator, four suction KOD’s, apropylene condenser and other accessories. Itprovides refrigeration at four different levels viz.–7°C(for LPG unit), -28°C, –41°C and 18oC (for C2+recovery unit).

Problem Effect of the problemFrequent tube leakage of C2/C3column reboiler which usessaturated LP steam as heatingmedium.

This may be due to the carryoverof free moisture along with the LPsteam on account of ineffectivede-superheating

Intermixing of hydrocarbon andcondensate water

Increase of pressure in thesteam/condensate side of thereboiler leading to restriction insteam flow

Frequent tube leakage inPropylene condensers.

Loss of propylene

Enhancement of microbiologicalgrowth in cooling water system

LPG UNITProblems experienced:-

Problem Effect of the problemstLess vapor load in 1 stage on

account of no vapor available fromEE-015.

Since, EE-015 was isolated fromthe propylene side, no propylenevapor was available from it for the

st1 stage of propylene compressor.stTherefore, the 1 stage runs with

antisurge valve in open condition.

Imbalance of vapor load amongthe stages leading to higher steamconsumption

LPG UNITProblems experienced:-

Measures BenefitsTwo stage controlling of BF waterflow to Desuperheater.

This helps in gradual reduction ofBF water pressure instead ofsingle stage pressure reductionfrom 130 kg/cm2 to 4 Kg/cm2

Better controlling over the LPsteam temperature ensuringexact saturation of LP steam.

No free water is carried overwith the LP steam which maycause tube leakage in thereboiler upon impingement

Satellite dosing at the coolingwater inlet for the individualpropylene condensers.

This localized dosing may behelpful in reducing corrosion in thecooling water side of thecondensers

Reduction in frequency of tubeleakage of propylene condenser

LPG UNITMeasures adopted to counter the problems:-

Measures BenefitsPropylene vapor load sharing

st nd rdbetween 1 , 2 & 3 stages ofpropylene compressor.

Under this modification, thepropylene vapor available from

stEE-035 is partially diverted to 1stage of the propylene compressor

nd rdalong with the 2 & 3 stages. Assta result, 1 stage gets the required

vapor load.

Even distribution of vapor loadamong all the stages

Reduction in r.p.m ofcompressor resulting intosaving of steam

LPG UNITMeasures adopted to counter the problems:-

08 EE 015

B/L I/V24”-RP-09-2228-B4A-IC

FLOW LINE8”-RP-08-B1A-1C08 PCV 3103

TO 4TH STAGE SUCTIONANTISURGE

09 VV 018

I/VK OD-1

I/VNEW

¾”

RP FROM 09PA13

LPG UNIT24” RP-09-2218-B4A-IC TO KA 003 1ST

STAGE SUCTION

09 HV 2201

8”-RP-08-B1A-1C LINE

08 EE 035

10”-RP-08-3610-B1A-1C

08 FCV 3602

ANTISURGEFLOW LINE

09 VV 019

ANTISURGEFLOW LINE

FROM08EE-019

08PCV3601

6”B/P I/V

EXISTING LINE

NEW LINE

09 VV 021

K OD-4

K OD-2

LEGEND

09 VV 020

K OD-3

RP FROM 09VV017

I/V

Earlier status Present statusThe pump was being used totransfer liquid propylene toEE-019.

The pump (18.5 KW) isstopped and liquid propyleneis being transferred by utilizingthe pressure differential.

As a result, 148 MWH ofenergy is saved annually.

LPG UNIT

Additional Measures adopted to increase plant performances:-

Benefit

Saving of Rs 5.10 Lakhs per annum.

Earlier status Present statusThe pump was being used totransfer Naphtha to storage.

The pump (22 KW) is stoppedand Naphtha is beingtransferred by utilizing thepressure differential.

As a result, 73 MWH of energyis saved annually (considering10hrs per day of pumpoperation).

LPG UNITAdditional Measures adopted to increase plant performances:-

Benefit

Saving of Rs 2.52 Lakhs per annum.


The average efficiency of thecooling water pumps of CT-3 wasaround 84%

The impellers & casings of thepumps are coated with flake glassfilled synthetic coating leading toreduction in frictional energy loss

As a result, the average efficiencyof the pumps is enhanced by 7%

LPG UNITAdditional Measures adopted to increase plant performances:-

BenefitSaving of Rs 24.5 Lakhs per annum on account ofefficiency enhancement of the pumps.

Storages Type of Storage No Capacity

LPG Mounded Bullets 7 32800 Meach

Propane Mounded Bullets 2 32800 Meach

C2/C3 Spheres 8 31500 Meach

Pentane Pipeline bullet 1 3825 M3

NAPHTHA Atmospheric Tanks 2 3850 M each

STORAGE FACILITIES FOR PRODUCTS

ME

RC

APTO

N D

OS

ING

LPG RECIRCULATION LINE LPG FROM UNIT

LPG MOUNDED STORAGEPSV TO FLARE

CAPACITY: 2800 M3DIAMETER: 6 MLENGTH: 96 M

MOUNDED BULLET

TO LOADING GANTRY

LPGLOADINGPUMP

VAPOR BALANCE LINE

LPG MOUNDED STORAGES :

LPG MOUNDED STORAGES

”-- ”--

ROV2403

FLAREKOD

PENTANE STORAGE PSV

PENTANE TOGANTRY

”--

”--

ROV2401

12” P-43-2406--B1A

STORAGE

PENTANE ROAD LOADING PUMPS

PENTANE FROM UNIT

6” P-432419--B1A

FROMMOUNDEDSTORAGE

TO MOUNDED

TO FLARELT 2401 LT 2402

VAPORROV2402

BALANCE

LINE8” P 43-2418--B1A

24 FINGERS OF 36” EACHCAPACITY:NOMINAL-4500 M3LIQUID STG--3825 M3

12” P 43-2401--B1A

LT 1501 LT 1502

LI 1504

PSV 1501 A/B PSV 1502 A/B

PSV 1501 CPSV 1502 C

SAFE HEIGHT

NAPHTHA STORAGEATM VENT AT

LI 1503

NAPHTHAFROMUNIT

NAPHTHALOADINGPUMPS A/B

NaphthaSTORAGETT-003 A

NaphthaSTORAGETT-003 B

CAPACITY=765 M3 EACH

HEIGHT: 13.5 MDIAMETER: 9.0 M

NAPHTHA TOLOADING GANTRY

PROPANE MOUNDED STORAGE (2 NOS.)

PSV TO FLARE

MAXIMUM STORAGE CAPACITY- 1200MTROV

PROPANE RECIRCULATION LINE PROPANE FROM UNIT

ROV

MOUNDED BULLET

TO LOADING GANTRY

PROPANELOADINGPUMP

VAPOR BALANCE LINE

MOV 1702

LPG LOADING GANTRYFLAME ARRESTOR

WEIGH BRIDGE

MOV 1701

TT 1701

FV 1701

HS 1701HS 1709

BATCHCONTROLLER

Critical Equipments in Gas Sweetening Unit

1) HP ABSORBERS (2 IN

• Operating pressure (top) : 51.4kg/cm2a

•kg/cm2a

2) REGENERATORPARALLEL)

Operating pressure (top) : 1.9kg/cm2aOperating pressure (bot) : 2.2

Operating pressure (bottom) : 51.7 kg/cm2aOperating temp (top) : 97oC

••••

Operating temp (top) : 45oCOperating temp (bottom) : 71oCNo. of trays : 30Type of tray : Highcapacity Nye trays

•

•

Gas flow handled : 7MMSCMDAmine flow handled : 400 m3/hr

Operating temp (bot) : 123oCNo. of trays : 22Type of tray : 21 valve + 1chimneyNo. of reboilers : 4 kettle typeSteam flow to reboiler : 84 MT/hr

Critical Equipments in Gas Sweetening Unit

3) AMINE TANK

••

Operating tempNominal Capacity

: 45oC: 770 m3

SPENT AMINE & FRESH AMINE TANK EACHOF 400 m3 CAPACITY

4) AMINE CHARGE PUMPS (2 running + 1 standby)

•••••••

Suction pressureDischarge pressureDriverTypeNo. of stagesPower ratingHead

: Atmospheric: 62 kg/cm2a: HT motor: Multistage centrifugal:5: 1.1 MW: 590 m

Critical Equipments OF C2+ Recovery Unit

1) KE 001 (FEED GAS EXPANDER COMPRESSOR) MAKE: MAFI TRENCH, USA• Comp suction pressure• Comp discharge pressure• Exp. suction pressure• Exp. discharge pressure• Comp. Suction/discharge temp• Exp. Suction/discharge temp• Operating speed• Power

2) DEMETHANISER• Operating pressure (top)• Operating pressure (bottom)• Operating temp (top)• Operating temp (bottom)• No. of trays• Type of tray• No. of reboilers

: 50 kg/cm2a: 55 kg/cm2a: 52 kg/cm2a: 22 kg/cm2a: 40oC/ 50oC: -67oC/--97oC: 13800 rpm: 3.6 MW

: 21.9 kg/cm2a: 22.2 kg/cm2a: -97oC: 5--12oC: 35: 34 valve + 1 chimney: 2 (bottom + side)


3) KE 002 (DEMETH O/H EXPANDER COMPRESSOR)MAKE: MAFI TRENCH, USA

• Comp suction pressure : 10.8 kg/cm2a• Comp discharge pressure : 12 kg/cm2a• Exp. suction pressure : 21.7 kg/cm2a• Exp. discharge pressure : 12 kg/cm2a• Comp. Suction/discharge temp : 10oC/ 28oC• Exp. Suction/discharge temp : -101oC/-117oC• Operating speed : 8500 rpm• Power : 2.7 MW

4) DEMETHANISER PRESTRIPPER• Operating pressure (top) : 22.1 kg/cm2a• Operating pressure (bottom) : 22.4 kg/cm2a• Operating temp (top) : -38oC• Operating temp (bottom) : 54oC• No. of trays : 17• Type of tray : 16 valve tray+ 1 chimney tray

• No. of reboilers : 1 (Thermo--syphon)• Steam flow : 2.8 MT/hr


5) LEAN GAS COMPRESSOR (2 IN PARALLEL)

MAKE: BHEL, HYDERABAD

DRIVER: GAS TURBINE (GE, FRAME V)

CONTROLS: MARK V SPEEDTRONIC

• No. of stages

• Type

• 1st stage suction pressure

• 1st stage discharge pressure

• 2nd stage suction pressure

• 2nd stage discharge pressure

• Operating speed

• Power

• Fuel gas cal value

:2

: Centrifugal

: 10.8 kg/cm2

: 24 kg/cm2

: 23.8 kg/cm2

: 54 kg/cm2

: 9896 rpm

: 13.8 MW

: 8190 kcal/Sm3


6) RESIDUE GAS COMPRESSOR


DRIVER: STEAM TURBINE (BHEL)

CONTROLS: WOODWARD GOVERNOR

• No. of stages : 1

:

:

:

:

:

• Type

• Suction pressure

• Discharge pressure

• Operating speed

• Power

Centrifugal

23.2 kg/cm2a

54 kg/cm2a

13177 rpm

2.75 MW

• Inlet steam pressure/temp : 41 kg/cm2a/365oC

• Outlet steam P/T

• Steam flow

:

:

4.5 kg/cm2a/140oC

30 MT/hr

Critical Equipments OF LPG Unit

1) PROPYLENE REFRIGERANT COMPRESSOR


DRIVER: STEAM TURBINE

CONTROLS: WOODWARD GOVERNOR, CCC ANTISURGE CONTROL

No. of stages

• Type

• 1st stage suction pressure

• 2ND stage suction. pressure

• 3rd stage suction Pressure

• 4th stage suction. Pressure

• 4th stage discharge pressure

• Operating speed

• Power

• VHP steam flow

:

:

:

:

:

:

:

:

:

:

4

Centrifugal

1.28 kg/cm2a

2.3 kg/cm2a

4.8 kg/cm2a

6.7 kg/cm2a

17.3 kg/cm2a

6216 rpm

8.77 MW

57 MT/hr

THANK YOU

Date post:	14-Dec-2015
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