Compressed Natural Gas

Gas

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Why Use Alternative Fuels?     

Energy Diversity Air Quality Improvement Greenhouse Gas Emission Reductions omes c conom c eve eve opmen

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Compressed natural Gas

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Urban Pollution

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Case Study of Delhi

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Smo Smo Beca Became me Perv Pervas asiv ive e

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FLEET COMPOSITION OF INDIAN VEHICLES (1997) (Source: TERI)

(Two wheelers (71%) & Three wheelers (5%) occupy significant places in the Indian transportation sector) 9/10/2013


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an mar March 31, 2001, India Supreme Court ruling

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Heavy duty (CNG). 

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Taxis and auto rickshaws must be replaced with engines running on clean

A natural gas gas pipeline from Mumbai supplies natural gas to New Delhi.

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LightLight-duty -duty 

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As of April 1, 2000, 2000, nonnon-commercial -commercial emission standards. Commercial vehicles, such as taxis, must be also meet Euro II emission standards or use CNG In order to be registered in the Capital Region of New Delhi.

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Alternative Fuel Vehicles Available Now   

Ethanol Natural Gas Propane (LPG)

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Why Natural Gas Chosen? 1. Natural gas is one of the cleanest of all fuel sources available 2. Huge potential of unexploited natural gas rese eserves ves exis existts in Indi India a .

of utilizing unexploited gas reserves by conv conver erti ting ng them them into into liqu liquid ids s

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Gas Reserves In India 1. 1. G Gas Ga as rese reserv rves es of of N NE E rre regi eg gion io on n - Tripura Trip Tripur ura a 2. 2. G Gas Ga as hydr hydrat ates es in in deep ep sea sea 3. 3. G Gas Ga as re rese serv rves es in deepwater deep de epwa wate terr

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NATURAL GAS

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HISTORY

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Natural Gas Vehicles Dilemma 

Very Low Emissions

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Good Performance

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Lower Cost Fuel

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Limited Range, but ade uate for most Applications Few Refueling Stations Higher Cost Vehicle Indian buses generally use 140140-160 -160 horsepower .

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Forms of Natural gas Storage 

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liquefied compressed gas (LNG). In order to liquefy it at atmospheric pressure, it is necessary to bring it to a temperature of --162 162 °°C. C. As a result it is used mainly in the form of Compressed Natural gas (CNG)

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CNG tanks 

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u and no composite material is allowed. A brand new, new, good quality CNG CNG kit with cylinder costs around 32,000 rupees or $6 400 while whil e a substandard substanda subst andard rd locally loc ally---made made mad e welded version is half the amount.

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Refueling: 

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CNG refueling stations using Tulsa Gas technologies equipment. e n a upreme our as man a e that at least 90 refueling stations be made available. Taxi cab drivers and rickshaw drivers fill at 68 “daughter stations.” Natural as buses are filled at 3 “mother stations.” The methane content for compressed natural gas is 88 percent.

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PROBLEMS WITH CNG DISPENSING STATIONS  

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neven s r u on o s a ons Inadequate pressure in daughter stations Overrunning of compressors supply Shortage of trained manpower

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CNG Induction Techniques

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SI Combustion technology

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Gasoline Car BiBi-Fuel -Fuel Conversion

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What does the Conversion kit comprise of ?        

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The Cylinder The Vapor Bag The High Pressure Pipe The Refueling Valve The Pressure Regulator e asas- r xer xer The PetrolPetrol-Solenoid -Solenoid Valve The Selector Switch 36

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Typical Gas Conversion 9/10/2013

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Typical Gas regulator 9/10/2013

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Typical Gas & Petrol Solenoid 9/10/2013


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Various Design of gas mixers 9/10/2013

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Fuel Mode Switch 9/10/2013


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Dedicated CNG Conversion of Diesel Engines ••Replacing Replacing injector by Spark plug ••Machining Machining the piston to decrease CR ••Gas Gas Conversion Kit installed

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Transit buses 

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Only two Indian chassis manufacturers exist-exist--TATA TATA and Ashok Leyland. Natural gas buses are using stoichometric Cummins engines. private operators are installing conversion s. ugas ugas s e cer e company or CNG bus conversions.

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Tuning up gas engines: • Stoichiometric engines (=1), in other words, the air fuel ratio is exactly the theoretical required for combustion • Lean mixture engines (normally = 1.4 )

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Efficiency of CNG Engines 

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e es gas powere eng nes ac eve a level of efficiency in the order of 36 - 37% 37% Which is above petrol engines Below modern diesel engines

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Safety with CNG

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Natural Gas

What is natural gas? 

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Mainly methane(C methane(CH CH4)

also contains heavier gaseous hydrocarbons such as ethane ethan thane e ((C C2H6), propane prop propan ane e ((C C3H8) and but bu butane tan ane e (C (C4H10), as well as other sulphur containing containing gases, gases, in varying varying amounts exact composition of natural gas varies between gas fields.

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Composition component

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Methane(CH4)

80-95

Ethane(C2H6)

5-15

ropane

an

u ane

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Sources of natural gas 

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It is found in oil fields fiel fields ds and natural gas fields fields,, and in coal beds The largest two natural gas fields are probably South South Pars Pars Gas Gas Field Field in Iran Iran and and Urengoy Urengoy gas gas field field in Russia, Russia, 13 with reserves on the order of 10 m³ Gas produced from oil wells is called casinghead gas or associated gas

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Storage

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It can be stored in two forms: Liquefied natural gas (LNG) and compressed natural gas (CNG)

CNG Fuel 

Large-scale Large-scale use since 1960’s

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Some 3,500,000 CNG vehicles now in operation worldwide

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Mostly in Italy, Argentina, Brazil, Pakistan, etc. as lower cost fuel Growing rapidly for transit operations in Europe as lower emission fuel Some 7,500 fill stations

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CNG Fuel – – Temperature Temp Tem p erat er atu u r e Eff Effects ect ec t s 

Typically stored at 3,600 psi at 70ºF ,

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correspondingly goes up or down

CNG Fuel – – Filling Fil Fi l l i n g  

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During filling, gas heats up as it compresses in the tanks T icall stations onl fill to service ressure of 3 600 psi End up with 3,600 psi at some elevated temperature (say 100ºF) in the tanks As gas cools to ambient (say 70ºF), pressure of gas decreases End result is less as - instead of havin a fill of 3 600 psi at 70ºF, one has say 3,400 psi at 70ºF

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To prevent underfills 

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Tanks can be slowly filled to allow heat to dissipate

Tanks can be pressured beyond service pressure, i.e. fill so that one gets higher pressure at a higher temperature, thus cooling to 3,600 psi at 70ºF Tanks actually designed to be filled up to 1.25 times service pressure (all qualification testing done at 1.25 times)

Fuel Fuel Tank Tank Techn Techn ologi ol ogi es 

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4 basic types of tank designs which design to use depends on need to reduce weight and how much can pay All designs have equivalent safety, as all meet requirements of same standards Design type can also determine how a tank may be handled, and how it may be filled

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Type 1 & Type 2 Tank Tank Desig ns

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Cheap but heavy

Type 2 - Metal liner liner reinforced reinforced by composite composite wrap (glass (glass or carbon fiber) around middle (“hoop wrapped”)

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Liner takes 50% and composite takes 50% of the stress caused by

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Less heavy, but more cost

Type 3 Tank Tank Desig n 

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Metal liner reinforced by composite wrap “ ” Liner takes small amount of the stress Light-weight, Light-weight, but expensive

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Type 4 Tank Tank Desig n 

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Plastic gas gas--tight -tight liner reinforced by composite “ ” Entire strength of tank is composite reinforcement Light Light--weight, -weight, but expensive

CNG performance 

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The octane rating for CNG is higher than that for asoline in a dedicated en ine a CNG vehicle’s power, acceleration, and cruise speed can be greater than that of a gasolinegasoline -powered -powered vehicle. In addition, due to the cleaner burning characteristics of natural gas, CNG vehicle engines can run more efficiently than a gasoline powered vehicle, CNG engines are also generally less noisy than diesel engines.

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Safety 

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CNG has a narrow flammability range, making it an inhe herrentl safe afe fue fuel. It is nonnon-toxic -toxic CNG also disperses rapidly, minimizing ignition risk relative to gasoline However, leaks indoor may form flammable mixture in the vicinity of ignition source

Emissions 

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Reductions in carbon monoxide emissions of 90 to 97 percent, and reductions in carbon dioxide emissions of 25 percent. Reductions in nitrogen oxide emissions of 35 to 60 percent. Pote Potent ntia iall redu reduct ctio ions ns in nonm nonmet etha hane ne h droc drocar arbo bon n emissions of 50 to 75 percent. Fewer toxic and carcinogenic pollutants, and little to no particulate matter produced.

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Maintenance working on CNG vehicles 

The oil in a CNG vehicle does not need to be changed as frequently because CNG burns more cleanly than gasoline, producing less deposits in the oil.

LNG fuel 

Liquefied natural gas or LNG is natural natural gas that that has been rocessed to remove helium or im urities such as water, and heavy hydrocarbons and then condensed condens condensed ed into into a liquid at almost atmospheric atmospheri atmosphericc pressure pressure by by cooling cooling cooling itit to to approximately --163 163 degrees Celsius

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LNG is about 1/614th the volume of natural gas at

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Much more cost cost--efficient -efficient to transport


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Producing LNG by liquefaction

Preliminary processes 

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The raw feed gas supply arriving from a producing gas field must be clean and dr before li uefaction can take place It is scrubbed of entrained hydrocarbon liquids and dirt Treated to remove hydrogen sulphide and carbon dioxide Gas is cooled to allowed water to get condensed

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Then it is further dehydrated to remove even small amou am ount ntss of wate water. r. If mercury is present then it is also removed at this stage. Then the gas is filtered to ensure only methane and traces of other hydrocarbons are present.

Liquefaction 

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Liquefaction takes place through cooling of the gas using heat exchangers. In these vessels, gas circulating through aluminum tube coils is exposed to a compressed hydrocarbon-nitrogen hydrocarbon-nitrogen refrigerant. Heat transfer is accomplished as the refrigerant vaporizes, cooling the gas in the tubes before it returns to the compressor. The liquefied natural gas is pumped to an insulated storage tank where it remains until it can be loaded onto a tanker.

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Basic facts on LNG 

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LNG offers energy density comparable to gasoline or diesel. But its high cost of production and need of cryogenic temperatures to store it has prevented its widespread use. Natural gas fed into LNG plant is treated to remove water, hydrogen sulphide, carbon dioxide and other compounds which freeze at low temperatures.

Storage 

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LNG aboveabove-ground -ground tanks ta nks are ar e mainly mainl y of doubledoub double le--wall, -wall, wall , hi hi h-nic -nick ni nicke ckel kel ell stee steell cons constr truc ucti tion on with with extr extrem emel el effi effici cien entt insulation between the walls Large tanks are low aspect ratio (height to width) and cylindrical in design with a domed roof. Storage pressures are very low, less than 5psig.

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LNG Storage tank

Pipeline system


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Smaller quantities, 70,000 gallons and less, are stored in hori horizo zont ntal al or vert vertic ical al vacu vacuum um- ack umac acketed ressure ur ure vesse ss ssels. These tanks may be at pressures any where from less than 5 psig to over 250 psig LNG must be maintained cold (at ( at least below --117 117° 117°F °F) to remain a liquid, independent of pressure.

LNG performance performance, operation, and utility when compared with diesel 


The high ignition quality of LNG is similar to that of diesel, providing for similar durability and engine life overall.

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Safety 

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A LNG vehicle parked indoors and unmoved for a week or more will vent a flammable as mixture that could catch fire in the vicinity of an ignition source. refueling vehicles with LNG requires training because of the fuel’s ultra low temperature .

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It can cause frostbite if it contacts skin.

Emissions 

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Production of half particulate matter of average diesel vehicles. Can significantly reduce carbon monoxide emissions. Reductions of nitrogen oxide and volatile organic hydrocarbon emissions by 50 percent or more. percent depending on the source of the natural gas.

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Drastic reductions in toxic and carcinogenic pollutants.

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Maintenance 

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LNG’s cleaner burning characteristics can result in longer en ine ine life life an and d redu reduce ced d ma main inte tena nanc nce e cost costs. s. Use of LNG eliminates the periodic tank inspections Because of the fuel’s below freezing temperatures, only trained personnel should maintain LNG vehicles.

Exhaust emissions 

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CNG emissions are compared with diesel and B20 ( diesel blend lend with ve etable oil THC, NOx, and PM emissions of CNG engine are significantly lower than diesel, with a reduction of 67%, 98% and 96% respectively. No significant reduction in CO is observed.

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Unregulated emissions 

Carbonyl compounds 

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CNG emits 95% lower formaldehyde with respect to diesel fuel.

PAHs and nitro PAHs 


Formaldehyde is most abundant compared to other carbonyl .

Use of CNG results in significant decrease in emissions: a reduction of at least 98% 98% and 88% was observed for PAHs associated to PM and vapor phase.

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Unregulated emissions

PAHs associated with particulate matter

PAHs associated with vapour phase


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Carbonyl compounds

Compressed ompr essed Natur Natura al Gas: Storage Sto rage and Di Di spensing spensi ng 

There are two types of CNG refueling systems 

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, the output of the compressor at one time. These vehicles are then refilled over several hours of compressor operation. Slow fill is considered practical only for vehicles of single fleet. FastFast-fill:In -fill:In fast systems, enough CNG is stored so that several vehicles can be refueled one after the other, just like refueling

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Basic Elements of a FastFast-Fill -Fill CNG Refueling System 

Storage

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Piping

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Dispensers

• Leak Leak detec detection tion sy syste stem m • Fire sup suppre press ssion ion sy syste stem m • Lightn ightning ing prote rotectio ction n

Compressors 

Reciprocating compressor

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Multistage (usually four stages)

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Gas is compressed from 35 kPa to as high as 31 MPa.

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Storage 

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Cylinders . . Cylinders steel. Cylinders

are made according to either or pressure vesse co e. are made only from carbon

are placed on a concrete slab . CNG storage cylinders can also be placed in underground vaults but usually not preferred.

Piping 

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Piping must be compatible with natural service pressure without failure. Stainless steel seamless tubing is commonly used. Threaded and compressioncompression-type -type fittings a o no use gas e s or sea an s are also allowed.

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Dispensers 

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Dispensers are used to direct CNG from the fast--fill fast -fill systems). They typically incorporate a sort of onon-off -off switch activated by removal of the refueling nozzle and a meter to measure the amount of CNG dispensed. spensers are usua y ma e o sta n ess steel CNG dispenser nozzles are made from aluminum and stainless steel

Control Systems 

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Control systems are of two typestypes-mechanically -mechanically . Computer controlled systems offers flexibility not possible with mechanical systems. Computer controlled systems provide functions such as accounting of the amount of the fuel .

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Leak Detection Systems 

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Leak detection system usually use methane detectors. Methane detectors are usually placed above the ground level at points where the released gas is likely to pass as methane rises when released. Most methane detectors are set to alarm methane in air is detected detected (about 1% methane in air). Some refueling facilities use twotwo -stage -stage approach to methane detection and alarm.First alarm is sounded when 20% LFL

Fire Suppression Systems 

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These systems are dry chemical using A puff test should be normally carried carried out after installation of fire suppression systems. Puff tests not only shows the coverage a can e o a ne u a so es s e components of the fire protection systems.

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Lightning Protection 

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CNG refueling systems located outdoor s ou a e g n ng ng pro ec on n o account. Lightning strikes can damage the refueling system and cause fuel release and/or fires

on Exhaust Emission

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Fuel Quality Trends in India Diesel * Cetane number increased from 42 to 45 in 1995 and further increased to 48. Need for further increase in o e asse ssesse sse . * Distillation limits became stringent from year 2000 in view of no clear trends further control of T90/T95 to be examined. * Sulphur content reduced from 1% to 0.5% in the year 1996 and further reduced to 0.25% in the year 2000. ey o e . n u nee s o e n e w engine technology. * Benefits of of multifunctional multifunctional additives being examined. examined. Likely benefits in terms of fuel economy and emission reduction. 

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Gasoline Quality And Emissions

Note: (+) Desirable; (-) Undesirable; Blank – NO significant effect 9/10/2013


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ROLE of Fuel Additives 

Additives are rapid, economic and easy means or - Improving Improving fuel performance performance properties. - Control Control fuel fuel quality quality during during , . - Control Contro Controll emissions. emissi emissions ons..

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MFA In Gasoline 

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Gasoline stability problem - inclusion inclusion of cracked cracked stocks stocks in gasoline gasoline - gasoline deterioration deteri deterioration oration during during storage storage Results in - formation formation of gum and sediments sediment sedimentss in storage. storage. - Gummy deposits deposits in engine engine intake system. system. - Engine performance performanc performance e deterioration deterioratio deterioration n - Loss of of fuel fuel economy. economy economy.. - Increase Increa Increase se in emissio emi emission. ssion. n. . Solution of problem - Refinery Refine Refinery ry processin proce processing ssing g - chemical chemical treatment treatment of gasoline with with additives additives 102

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MFA In Gasoline 

INTERNATIONAL SCENARIO U.S.A * As per clean air act gasoline must contain certified additives. EUROPE * Growing use of deposit control additives (DCA) ASIA AND AUSTRALIA AUSTRALIA * Japan, Singapore, S. Korea, New Zealand, Australia-USE Australia-USE guidelines from US EPA * In Thailand DCA regulation system is in place

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Fuel Quality Trends in India Related to Emissions 

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Unleaded gasoline introduced in four metros from APR.1995 and all over the country from 2000. . . Volatility limits implemented from 1995 further review for evaporative emission control. Use of multifunctional additives in gasoline recommended in 1997 Use of oxygenates like MTBE started in some refineries for roduc roducin in unlea unleade ded d asolin asoline e Sulphur limit to be made stringent from year 2000 demand for further control from 2005 Benzene also to be restricted to 5% max. from 2000 demand for reduction upto 1% 9/10/2013


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Impact of Diesel Properties on Emissions

Note: (+) Desirable; (-) Undesirable; Undesirable; Blank – NO significant effect 9/10/2013

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Fuel Sulphur-PM Emission

Sulphur 0.25% . sulphate & H20 Absolute Emission g/kwh % of of Euro Euro 1 limit limit (0.36 g/kwh) % of Euro 2 limit (0.15 g/kwh) 9/10/2013


Sulphur 0.05% .

Reduction .

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Conclusion 

Main conclusion that flows logically from the most of the world will have to switch to alternative fuels for automobiles, sooner or later, the sooner the better for our own environment. industry to look ahead and formulate a strategy to make this switch smooth and timely.

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Compressed Natural Gas

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