ACKNOWLEDGEMENT

After the completion of my in plant training I intend to thank all the staff of GAIL (INDIA) Ltd. who directly or indirectly was responsible for making mystay(during the training period) fruitful. I am very grateful to the staff of GAIL who cooperated with me during the entire training period.First and foremost, I would like to thank Mr. P.K. Jain Chief Manager (training) for making it possible for me to come to GAIL and undergo the training.The people of IOP&S Unit( where we were deputed) deserve special mention. I extend my sincere gratitude toMr. A.K. Nashkar, HOD(IOP&S)Mrs. Sweta Rani, Dy Manager( PC Operation), (IOP&S) Finally, I would like to thank the field Engineers& GAIL family, who were in some way or other related to our successful training.

ABSTRACT

In plant training is a vital part in the progress of fledgling engineers. For me this was the first rendezvous of practical knowledge with the theoretical concepts acquired during the years in college. I am very fortunate that I got the opportunity of undergoing training in one of the most sophisticated and modern petrochemical plant, GAIL. The experience gained during the short stay here was fascinating to say the least. It was tremendous feeling to see the practical operation of different equipment and processes, which until now existed for me only in books. I was deputed in IOP&S unit for my training. I was overwhelmed by the sheer size and complexity of the plant. What still fascinates me, how such a big unit is being monitored and operated with the desired results. In this short stay it was possible for me to wholly decipher the detailed functioning of the plants; but still I was fortunate enough to get a sound overview of the unit.Thanks

CONTENT CERTIFICATE ABSTRACT ACKNOWLEDGEMENT LIST OF FIGURES LIST OF TABLES 1. Inroduction to gas industry 5-61.1 Exploration 5-61.2 Production 61.3 Consumption 6 2. Introduction to GAIL 7-82.1 Project configuration 93. GAIL, (PATA) Project 10-183.1 Upstream operation 10-15 3.1.1 gas sweetening unit 10-123.1.2 gas processing unit 133.1.3 LPG unit 143.1.4 Gas cracking unit 15 3.2 Downstream operation 16-183.2.1 Petrochemical 163.2.2 Linear low density polyethylene 173.2.3 High density polyethylene 18 4. IOP&S UNIT 19-42 4.1 Introduction to iop&s 194.2 Storage vessels 19-24 4.3 D m plant 25-314.4 Cooling tower and cooling tower efficiency 32-374.5 Raw water 38-42 5. References 436. Remarks

INTRODUCTION TO GAS INDUSTRY

fig 1.1

Gas demand in india is dominated by the power and fertilizer sectors which account for 66 per cent of the current consumption. In 2006, the total gas demand was around 152 MSCMD. The gas demand is expected to increase to 320 MSCMD, according to a report by Ernst & Young. Significantly, the share of natural gas in the overall fuel mix is expected to increase from 8 per cent in 2006 to 20 per cent by 2025.Reliance industries plans to invest between US$ 5.45 billion to US$ 6.54 billion over the next three years to lay a 10,000 km pipeline.

Exploration and production:

Exploration:

Exploration for and production of natural gas are the first steps in delivering gasoline to your car, heat to your home, raw material to business and industry, fertilizer to farmers fields and for many other aspects of daily life. Many people are unaware of the important role that gas exploration and production play in their daily lives. Without successful exploration and continued production, our nations energy security and the economic prosperity that goes along with it will be compromised.

Production:

1. Domestic production of crude oil has increased to 34.11 MT in 2007-08 from 33.98MT in 2006-07

2. The production of petroleum products went up to 144.93 MT in 2007-08 from 135.26 MT in 2006-07

3. The production of natural gas went up to 32.27 billion cubic meters tones in 2007-08 from 31.74 BCM in 2006-07

4. The projected production of crude oil during the 11th five year plan(2007-12) is 206.76 MMT while that of natural gas is 255.27 BCM

5. Production of gas from Reliance industries eastern offshore KG D-6 fields, with a life of 11 years , started on april 1 and will increase to 80 million standard cubic meters per day(MSCMD) by the end of the year. Production will help save US$ 9 billion in oil import.

6. Cairn india will commence the commercial production of crude oil from its rajasthan fields from September 2009. It is expecting a production of 175,000 barrels per day

Consumption:

Indias domestic demand for oil and gas is on the rise . As per the Ministry of Petroleum, demand for oil and gas is likely to increase from 176.40 million tons of oil equivalent ( mmton ) in 2007-08 to 233.58( mmton ) in 2011-12

INTRODUCTION TO GAIL

GAS AUTHORITY OF INDIA LTD. (GAIL) is one of the outstanding public enterprises within the country today. It is one of the MAHARATNA Company in INDIA.The setting up GAIL(India) LTD., in august 1984, heralded a new era of natural gas in the country. GAIL is now 29 glorious years of service to the nation.Since 1984, GAIL has made significant contribution to the nations economy by supplying natural gas through its pipeline network for1. Generation of over 87,000 MW of power2. Production of over 145 million tons of urea3. Production of LPG for over 7 cr. households in the country4. Over 5.7 lakhs vehicles in the country today running on CNG supplied by GAIL and over 7 lakhs households on piped natural gas(PNG) in the country.5. Production of petrochemicals of around 4 lakhs mts which is used in the plastic industry.

The natural gas infrastructure of around 7,000 km. accounting for over 82% of total pipeline infrastructure in india , set up so far by gail has contributed enormously to the economically and socially critical sectors such as fertilizers and power.GAIL has the distinction of pioneering the clean fuel revolution for transport sector in the country with the introduction of CNG in Delhi and Mumbai which has significantly helped in reducing pollution levels in these two cities.

It provides ready market access to the domestic gas producers, making gas available to the customers including those remotely located and devoid of market access. It has provided cheaper, environment friendly alternative fuel and has reduced import dependency as natural gas has substituted liquid fuel such as naphtha, fuel oil, etc.GAILs pipeline network to the gas consumers in the states of:

1. Gujarat2. Maharashtra3. Rajasthan4. Madhya Pradesh5. Delhi6. Haryana7. Uttar Pradesh8. Andhra Pradesh9. Tamilnadu10. Assam11. Tripura

In addition to supplying natural gas to various consumers, GAIL has also setup 7 LPG plants and a petrochemical plant to extract value added products from gas. Gail today handles about 95% of natural gas business in India , through its 3900km of pipelines in country. Gail is also one of the largest LPG producers in India with a liquid hydrocarbon production. It produces around 1.35 MMTPA of liquid hydrocarbon including LPG for domestic consumption. It has emerged as the no. 1 gas company in India. It has won the excellent performance award for past several years, as well as safety award. It has ISO 900 certificate for its pipeline system and also ISO 14001 for HVJ pipeline.Entering into the field of petrochemical, GAIL has set up petrochemical complex at PATA(UP).The natural gas to the complex is coming from vijaipur through HVJ pipeline for producing petrochemical conversion of ethane, propane& LPG from natural gas. The ethane& propane are recovered from natural gas in GPU & set to gas company unit to produce ethylene& propylene while LPG is recovered in LPG is recovered in LPG recovery unit. Ethylene is converted to final products HDPE& LLDPE.

Project configuration:

S.no unit capacity licencor

1Gas cracker unit4,00,000 TPAU.S.A.

2Gas sweetening agent12.66 MMSCMDTOTAL FINAEIF

3C2/C3 Recovery4,00,800 TPAE.I.L.

4LLDPE2,10,000 TPANOVACOR

5HDPE 1& 21,00,000 TPAMITSUI,JAPAN

6LPG& PROPANE2,98,480 TPAE.I.L

7BUTENE PLANT10,000 TPAI.F.P., FRANCE

Various utilities and offsite facilities have been provided in the complex. These include raw water, cooling tower, compressed air, DM water, nitrogen flare, storage system are provided.

GAIL, PATA PROJECT

GAS SWEETNING UNIT LIC: TOTAL FINAEIF

LLDPE/ HDPE SWING UNIT LIC: NOVACOR Rich gas from

BUTENE 1 LIC: I.F.P., FRANCEHDPE UNIT LIC: MITSUI, JAPANGAS CRACKING UNIT LIC: USAGAS PROCESSING UNITvijaipur

C2/C3

LPG UNIT LIC: E.I.L.

PROPYLENE LPG PROPANE

UPSTREAM OPERATION GAS SWEETENING UNIT

Amine gas treating also known as gas sweetening and acid gas removal, refers to a group of processes that use aqueous solutions of various alkyl amines( commonly referred to simply as amines) to remove hydrogen sulfides and carbon dioxide from gases. It is a common unit process used in refineries and is also used in petrochemical plants, natural gas processing plants and other industries.Processes within oil refineries or chemical processing plants that remove hydrogen sulfides or mercaptans are commonly referred to as sweetening processes because they result in products which no longer have the sour, foul odour of mercaptan and hydrogen sulfide.There are many different amines used in gas treating:1. Monoethanolamine (MEA)2. Diethanolamine(DEA)3. Methyldiethanolamine(MDEA)4. Diisopropylamine(DIPA)5. Aminoethoxyethanol ( Diglycolamine) (DGA)The most commonly used amines in industrial plants are the alkanolamines MEA, DEA, and MDEA.Amines are also used in many oil refineries to remove sour gases from liquid hydrocarbon such as LPG.

Description of a typical amine treaterGases containing H2S or both H2S and CO2are commonly referred to assour gasesoracid gasesin thehydrocarbonprocessing industries.The chemistryinvolved in the amine treating of such gases varies somewhat with the particular amine being used. For one of the more common amines,monoethanolamine (MEA) denoted asRNH2, the chemistry may beexpressed as:RNH2+ H2SRNH3+ SH-A typical amine gas treating process (as shown in theflow diagrambelow) includesanabsorberunit and aregeneratorunit as well as accessory equipment. In theabsorber, the downflowing amine solution absorbs H2S and CO2from the upflowing sour gas to produce a sweetened gas stream (i.e., a gas free of hydrogen sulfide and carbon dioxide) as a product andan amine solution rich in the absorbed acid gases. The resultant "rich" amine is then routed into the regenerator (a stripper with areboiler) to produce regenerated or "lean" amine that is recycled for reuse in the absorber. The stripped overhead gas from the regenerator is concentrated H2S and CO2. In oil refineries, that stripped gas is mostly H2S, much of which often comes from a sulfur-removing process calledhydrodesulfurization. This H2S-rich stripped gas stream is then usually routed into aClaus processto convert it into elementalsulfur. In fact, the vast majority of the 64,000,000 metric tons of sulfur produced worldwide in 2005 was byproduct sulfur fromrefineries and other hydrocarbon processing plants.Another sulfur-removing process is theWSA Processwhich recovers sulfur in any form as concentrated sulfuric acid. In some plants, more than one amine absorber unit may share a common regenerator unit.fig 1.2Process flow diagramof a typical amine treating process used in petroleum refineries, natural gas processing plants and other industrial facilities.The amine concentration in the absorbent aqueous solution is an important parameter in the design and operation of an amine gas treating process. Depending on which one of the following four amines the unit was designed to use and what gases it was designed to remove, these are some typical amine concentrations, expressed as weight percent of pure amine in the aqueous solution: Monoethanolamine: About 20% for removing H2S and CO2, and about 32% for removing only CO2. Diethanolamine: About 20 to 25% for removing H2S and CO2 Methyldiethanolamine: About 30 to 55%% for removing H2S and CO2 Diglycolamine: About 50% for removing H2S and CO2The choice of amine concentration in the circulating aqueous solution depends upon a number of factors and may be quite arbitrary. It is usually made simply on the basis of experience. The factors involved include whether the amine unit is treating rawnatural gasorpetroleum refineryby-product gases that contain relatively low concentrations of both H2S and CO2or whether the unit is treating gases with a high percentageofCO2such as the offgas from the steam reforming process used inammonia productionor theflue gasesfrompower plants. Both H2S and CO2are acid gases and hence corrosive tocarbon steel. However, in an amine treating unit, CO2is the stronger acid of the two. H2S formsa film of iron sulfide on the surface of the steel that acts to protect the steel. When treating gases with a high percentage of CO2, corrosion inhibitors are often used and that permits the use of higher concentrations of amine in the circulating solution. Another factor involved in choosing an amine concentration is the relative solubility of H2S and CO2in the selected amine. For more information about selecting the amine concentration, the reader is referred to Kohl and Nielsen's book. The choice of the type of amine will affect the required circulation rate of amine solution, the energy consumption for the regeneration and the ability to selectively remove either H2S alone or CO2alone if desired.The current emphasis on removing CO2from the flue gases emitted by fossil fuel power plants has led to much interest in using amines for that purpose. In the specific case of the industrial synthesis ofammonia, for thesteam reformingprocess of hydrocarbons to produce gaseoushydrogen, amine treating is one of the commonly used processes for removing excess carbon dioxide in the final purification of the gaseous hydrogen

Gas Processing UnitGAIL is marketing gas processing units (GPU) products namely LPG, Propane, Pentane, Naphtha and by products of polymer plant namely MFO, Propylene & Hydrogenated C4 mix. LPG is being sold exclusively to PSU Oil Marketing Companies ( omcs) while other products are sold directly to customers in retail segment.GAIL is Indias major producer of propane, popularly known as GAIL propane. It is an eco friendly fuel and provides an effective way of reducing pollution and increasing productivity.GAIL produces and markets Pentane. It is primarily being used for reprocessing into iso, normal and commercial pentane used in EPS , PU and lab industry.Naphtha is primarily used by power, fertilizer, steel and petrochemical units. In power and steel it is used as a fuel, whereas in petrochemical , chemical, fertilizer units it is used as a feedstock.GAIL is presently operating 7 GPU located at Vijaipur (2 units), Auraiya, Vaghodia, Usar, Lakwa & Gandhar plant for production of main products viz. LPG & Polymer through GPU/GCU except usar, the following by products liquid hydrocarbons (LHC) are produced:Plants byproductsVijaipur propane, pentane, naphthaAuraiya propane, pentane, naphtha, MFO, Hydrogenated c4 mix, propylene, slop oilVaghodia naphthaGandhar pentane, naphthaLakwa solvex GL, naphtha

Liquefied Petroleum gas unit(LPG) GAIL is the company in India to own and operate pipelines for LPG transmission . . It has 1900 km LPG pipeline network, 1300 km of which connects the western and northern part of India and 600 km is in southern part of country connecting eastern coast. The LPG transmission system has the capacity to transport 3.8mmtpa LPG . LPG transmission through pipelines was 3337 TMT in year 2010-11.GAIL has a share of about 10% Indian LPG market in LPG production and 7% in LPG sales. Gail produces LPG through fractionation in GPU, Known as straight run LPG. Gails LPG is an eco friendly fuel and provides a cheaper and effective means of reducing pollution and increasing productivity.Characteristics of Gail LPG:1. Processed for natural gas2. Has a high vapour pressure3. Vapourizes at atmospheric temp. and pressure4. Clean fuel with almost nil unsaturated compound5. Has a high calorific value than refinerys LPG 6. Its homogenous composition results in more efficient combustion7. The air fuel ratio need not to be changed in each branch8. No impurities like sulphur, CO2 traces on N29. Has nil moisture contentIn auraiya PATA plant it produces 258250 MT/annumApplication of LPGDomestic: for use in householdAuto: for use as fuel in automobiles

Gas cracking unit(GCU)A gas cracker is any device that splits the molecules in a gas or liquid usually by electrolysis, into atoms. The end product is usually a gas. A hydro cracker is an example of a gas cracker. In nature, molecules are split often, such as in food digestion and microbial digestion activity. A gas cracker device splits the molecules at a rate much greater than that normally found in nature. In science and industry, gas cracker are used to separate two or more elements in a molecule. For example, liquid water or h20 is separated into hydrogen and oxygen gases.This is not to be confused with the splitting of the nucleus( nucleus power).Gas cracker: Petrochemical are usually manufactured in large scale from petroleum feed stocks.Naphtha , natural gas, refinery off gas from cookers and thermal crackers are good sources. Thus natural gas is one of the most wanted feed stocks for petrochemical production. The thermal cracking of natural gas proceeds at very high temp. resulting in olefins( mostly ethylene/propylene). The temp. in a gas cracker exceeds 1000 degree C. For ultimatedecomposition of gas into elements more than 1500 degree C is required. Thus , acetylene/carbon black production encounters such high temperatures. Usually oxy combustion methods are used for attaining such high temp.. BASF burners/kellogs burners are available in market fig 1.3Downstream operation

PetrochemicalsGails the countrys premier natural gas marketer& transporter, diversified into the manufacturing and marketing of downstream HDPE& LLDPE from natural gas cracking at its pata unit from 19th april 1999. The beginning was with a name plate capacity of 2,60,000 MTPA of HDPE & LLDPE. In FY 2009-10, the petrochemical business portfolio contributed over 28% of the segment gross profit.Gail is the only HDPE/ LLDPE plant operating in northern India and has a dominant market share in north India. The primary thrust markets for the polymer had been western India, but with the entry of Gail in the HDPE&LLDPE market verticals, today north India has also witnessed a rapid and significant growth in the polymer downstream processing verticals. In a successful span of about a decades of establishing and marketing its grades under the brand names Glex& Glene, Gail has alongside augmented its name plate capacity of HDPE&LLDPE to 4,10,000 MTPA by adding another dedicated HDPE downstream polymerization unit of 1,00,000 MTPA.GAIL has two trains of dedicated HDPE units of the Mitsui slurry technology license( capacity 2* 1,00,000 MTPA) and marketing the grades under the brand name of G lex and one train of the HDPE&LLDPE swing plant under the NOVACOR solution based technology license( capacity 2,10,000 MTPA).Further by adding 6th furnace & de bottlenecking of the plant, the Gails pata plant capacity will reach to 5,00,000 mts of ethylene & 5,00,000 MTs of HDPE&LLDPE producing capacity by FY 2011-12.GAIL has also formed a joint venture company by the name of M/s Bhramaputra cracker and petrochemicals ltd.( BCPL) to accelerate the GoIs only authorized petrochemical project in the north east of India( at Assam ,India). The bcpl is a JV between the government of Assam , GAIL INDIA ltd. OIL INDIA ltd.& NRL.Further Gail has plans to augment the installed capacity further by putting up new plants of HDPE/LLDPE by 500 KTA at pata, which is targeted to the operational by FY 2013-14

Linear low density polyethylene(LLDPE)This is the only LLDPE plant in North India. The plant installed new generation multi reactor spheriline process. The technology used is termed as Swing technology owing to its flexibility of producing both HDPE and LLDPE.Different sections:1. Monomer purification unit2. Polymerization section3. Catalyst, co catalyst handling and metering4. Prepolymerization5. Polymer drying6. Extrusion7. Product homogenization8. Product storage and bagging

High density polyethylene(HDPE)This is a MITSUI low pressure, bimodal, twin reactor slurry process. This plant is designed to produce HDPE and has two trains of equal capacity. The main feeds of this plant are ethylene, co monomer(1-butene and propylene) and hydrogen. Each train of the unit is capable of running in both parallel and series mode.Different section:1. Catalyst, co catalyst handling and metering2. Polymerization3. Separation and drying4. Extrusion and pelletization5. Product homogenization6. Product storage and bagging

fig 1.4

Integrated offset plant& storage(IOP&S) It is the midstream unit. It is required for different purposes:1. Storage vessels2. Nitrogen plant3. DM plant4. Cooling tower5. Raw waterStorage vessels:TYPES OF STORAGE VESSELS IN IOP&S:Following are the types of vessels used in Storage area :1.) Cylindrical vessels2.) Spherical vessels (HORTON SPHERES)3.) Double Walled Ethylene tanks 4.) Bullets5.) Mounded BulletsSpherical Vessels are generally preferred as its ratio of volume to surface area is less . Therefore large amount of material can be stored in less space. There are 14 Horton Spheres, 9 cylindrical storage vessels and 2 double walled ethylene tanks. Horton spheres present in storage area are of different fixed designed diameters such as 11.5m, 13m and 15m. There are 8 spheres of diameter equal to 15 m to store C2/C3 having their tag no. from TS - 101 to TS - 108 . Fire coating of thermolag is required in these C2/C3 storage vessels as temp conditions are very low. There are 2 Horton spheres of diameter equal to 11.5 m to store Propylene with their tag no. as TS 109 and TS 110 . There are 2 Horton spheres of diameter 13m to store Butene -1 having tag no. TS 112 and TS 113 . And there is a Horton sphere each for C4 mix ( tag no. TS - 111) and ethylene (TS -114) as well. Likewise C2/C3 Horton sphere, insulation is required in ethylene sphere also as its temp conditions are very low.There are 2 Double walled Ethylene tanks to store ethylene ( from GCU ) at -104c and 0.7-0.8 kg/cm2. As temp conditions are very low so insulation with perlite is done in the annular space. There are 9 cylindrical vessels in storage area . one for xylene , one for wash oil, one for hexane , one for cyclohexane , two for mixed fuel oil and two for SBP. There are 7 mounded storage bullets to store LPG as it is heavier than air. And there are 2 mounded bullets for storage of propane also.There are 2 storage bullets to store hydrogen also.PROPYLENE STORAGEIn UPPC propylene will be produced in the Gas Cracker as a product. For storing this propylene, two Horton spheres 44-TS-00-109/110 have been provided in the Offsite area. The spheres are 11.5m diameter and elevated by 5.5 m to cater to the transfer pump NPSH requirement. Propylene product sphere Tag No.44-TS-00-109/110Number of spheres Two Op. Pr. Kg/Cm2g7 to 17Op. Temp. 0C9.4 to 40Design Pr. Kg/Cm2g9.4 to 40Design Temp. 0C-40/+55Diameter M11.5Stored Capacity M3650MOCKilled Carbon SteelInsulation Fire Protection Paint

C2C3 STORAGE SYSTEMINTRODUCTION:The complex receives natural gas as its feedstock from Pipelines. This gas is first sweetened to remove CO2 and then sent to Gas Separation Unit for recovery of C2C3 which is mainly an ethane rich stream (70-84% ethane). When the gas comes through the LPG plant at Vijapur, the ethane percentage is high i.e. 84%. Otherwise when it is bypassed, the ethane percentage is low i.e. 70%. Similarly propane percentage is low in the former case (15%) than the latter case (26%). This is the feed stock to the Gas Cracker. The C2C3 comes through a 8 line from the C2C3 plant for storage at Offsites. Eight spheres each of 1500M3 capacity (15 M diameter) have been provided for this storage. This storage capacity is equivalent to 3 days production of C2C3 corresponding to 4,10,000 TPA ethylene production. Under normal conditions cracker will receive C2C3 directly from C2C3 plant and a small slip ream of 7 T/hr will be diverted to the offsite storage. Three pumps (41-PA-CF-004 A/B/C) of 100 M3/hr capacity each are provided to transfer C2C3 to GCU. Under normal condition (when C2C3 plant is running) this 7 T/hr will be pumped out of the storage spheres and is routed to join the main C2C3 rundown line leading to the GCU. Thus the entire system is kept chilled at a temperature of -2 to 5 0C. This is to ensure that the system can be taken in line immediately whenever required. The sphere is provided with facility to measure average temperature of the fluid by the probe mounted with servo type level transmitter on sphere top. C2C3 will be stored in the sphere at a temperature of -20C to 50C and a pressure of 22.5 Kg/cm2g. fig 1.5HORTONS SPHERE

fig 1.6 STORAGE TANKHYDROGEN STORAGE AND TRANSFERReceipt & Storage:Hydrogen is used as a chain terminator in polymeric reactions. So a continuous supply of H2 has to be ensured for the safe running of the polymer plants. Under normal conditions, Hydrogen coming from the PSA unit at GCU (at 19 Kg/cm2g) will be compressed by a MP compressor (41-KA RP-001) to 50Kg/cm2g and will be routed to the consumer. The balance hydrogen will be compressed in a HP compressor (41-KA-RP-002) up to 137 Kg/cm2g and stored in two H2 bullets (41-VV-00-118 A/B) of 70M3 capacity each. These bullets store H2 at a pressure of 137 Kg/cm2g. These will be in use when H2 is not available from GCU-PSA. The HP compressor can also be used as a standby of the MP compressor whenever required. PCV-2103 has been provided to let down HP hydrogen pressure to MP level for consumption. Provision is also there to evacuate the bullets by the same compressor whenever required.

Hydrogen Bullets Tag No.41-VV-00-118 A/B Number of Bullets Two Dia of Bullets M2.5Length of Bullet M13.2(Excluding Heads)Op. Pr. Kg/cm2g 137Op. Temp 0C Ambient Design Pr. Kg/cm2g 149 Design Temp0C55 Stored Capacity M370 MOCCarbon Steel InsulationNil Each bullet is provided with the following instruments:- -One pressure transmitter -One temperature gauge -One pressure gauge -Two safety valves (one in operation + one spare) Designed for fire case. Each bullet is provided with two process line, one fill-in and one line grouted to the consumer. All the process lines are provided with remote operated valve for isolation in case of any emergency i.e. fire, leakage, etc. Thus on closure of these valves, the bullet gets isolated from rest of the system. Both open and close push buttons and status indications of these ROVs are available in the control room. Each bullet is protected with a pair of safety valves (one operating + one standby) designed for fire case discharge capacity.

SAFETY IN STORAGE VESSELSFIRE: Spheres are protected against external fire by a layer of fire proofing paint which can stand fire for 2 hrs. Apart from this over this layer, there are networks of thermal fuses and water spray. Thermal fuses are small glass bulbs filled with a liquid set to break when it gets heated upto 790C and are located at the tip of an instrument air network. Thermal fuses seal the network thus pressurizing the entire network to level of instrument air pressure. The second network is that of fie water with a spray on the tips. Water is supplied to this network through a solenoid operated valve which normally remains closed. When the bulb breaks instrument air leaks out causing a drop in air pressure. A low pressure switch located on instrument air line to each sphere is actuated when pressure falls to 2.5 Kg/cm2g. This in turn actuates solenoid valves thereby closing ROVs of respective sphere and simultaneously opening solenoid operated valve on fire water line to the sphere. The sprays will drench the sphere at a rate of 10 LPM/M2 of sphere surface area. Instrument air is supplied through a restriction orifice so that when a bulb breaks only PSL of the affected sphere is actuated while instrument air network on other two spheres remain pressurized. ROVs on hydrocarbon lines and those on fire water lines are operate as described for the case of propylene storage. Instrument air to only bottom ROV is supplied through a volume bottle with capacity sufficient for two operations In the event of fire in the sphere area, the sphere is provided with security system to isolated the affected sphere from the others. All the spheres are provided with two nos. of safety valves sized for fire case (1+1). This safety valve will be protecting the sphere from over pressure by dumping the vapour generated due to fire. High expansion foam can also be applied on the ethylene tank. Around 5000 lpm of foam solution can be applied on the tank All the ROVs of the spheres are provided with close facility from field. The deluge valves on fire water sprinkler lines for adjacent tanks in the dyke shall get opened. The transfer pumps shall get tripped. LEAKAGE/ LINE RUPTURE: All the ROVs of the spheres are provided with close facility from the local control panel. All the deluge valves for the water sprinkler is provided with push buttons in the control room to open them manually. Gas detectors are provided near each ROV and one on the top of the sphere to alert the operator from gas leakage

Dm plantINTRODUCTION:De-mineralized water is required in GAIL, Pata complex to generate steam as well as for process use for injection, dilution, washing etc. in units like GCU, LLDPE/ HDPE (Swing), HDPE (Slurry). Treated raw water is fed to DM water plant to produce DM water of required quality. DM water is distributed to various users from DM water storage tanks (three in number) which can meet 6 hours normal requirement each. Three DM water pumps (2 Oper + 1 Standby) in D. M. Plant-1 and two DM water pumps (1 Oper + 1 Standby) in D. M. Plant-2 are provided to feed DM water to Power plant and process units. Brief description of DM plant is given in this section. For detailed description of DM plant, start up and shut down procedure. Vendors manual shall be referred. DM WATER REQUIREMENT: The estimated requirement of DM water for GAIL, Pata is given below: Normal Maximum (T/hr)(T/hr)GCU - 20LLDPE/ HDPE 5.0 10HDPE-I&II 10 20 Butene 1 - Caustic dilution - 7.0Spent caustic plant - 3.0BFW required for steam 120 130Generation HRSG 70 90 TOTAL DM WATER 210 275DM WATER CHARACTERISTICS:

pH:6.5 7.0Conductivity micromho/cm:0.2Total Silica as SiO2:0.02Turbidity :NILIron as Fe:0.005TDS :0.1Copper as Cu: