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
GAS SWEETENING UNITProblems experienced:-
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
GAS SWEETENING UNITProblems experienced:-
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
GAS SWEETENING UNITProblems experienced:-
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
GAS SWEETENING UNITMeasures adopted to counter the problems:-
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
GAS SWEETENING UNITMeasures adopted to counter the problems:-
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
GAS SWEETENING UNITMeasures adopted to counter the problems:-
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.
GAS SWEETENING UNITMeasures adopted to counter the problems:-
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
GAS SWEETENING UNITMeasures adopted to counter the problems:-
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
Earlier status Present status
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.
GAS SWEETENING UNITAdditional Measures adopted to increase plant performances:-
Benefits:-
The benefit is Rs 3 crores per annum on account of reduction inLP steam consumption
Earlier status Present status
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.
GAS SWEETENING UNITAdditional Measures adopted to increase plant performances:-
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
C2+ RECOVERY UNITProblems experienced:-
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
C2+ RECOVERY UNITProblems experienced:-
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.
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
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
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
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
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
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.
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
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
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
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
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
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
C2+ RECOVERY UNITMeasures adopted to counter the problems:-
Earlier status Present status
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
Earlier status Present status
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
C2+ RECOVERY UNITAdditional Measures adopted to increase plant performances:-
Benefits:-
Saving of Rs 20 lakhs per annum on account of reducedenergy consumption by the fans.
Earlier status Present status
Flare & Blowdownheaders of GPU werekept under positivepressure using fuel gasas end purge.
Nitrogen is being used atpresent for this purposein place of fuel gas.
C2+ RECOVERY UNITAdditional Measures adopted to increase plant performances:-
Benefits:-
Saving of Rs 28 Lakhs per annum on account ofsaving of fuel gas.
Earlier status Present status
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).
C2+ RECOVERY UNITAdditional Measures adopted to increase plant performances:-
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.
Earlier status Present status
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)
Critical Equipments OF C2+ Recovery Unit
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
Critical Equipments OF C2+ Recovery Unit
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
Critical Equipments OF C2+ Recovery Unit
6) RESIDUE GAS COMPRESSOR
MAKE: BHEL, HYDERABAD
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
MAKE: BHEL, HYDERABAD
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
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