GASEOUS FUELS

Dr G NAGARAJAN

Professor

Department of Mechanical Engg.

Anna University Chennai

Chennai 600 025

G A S E O U S F U G A S E O U S F U E LE L ADVANTAGES

- Consistency in Quality

- Easily Combustible

- Absence of Mineral Impurities

- High Efficiency of Combustion

T Y P E S N a t u r a l l y O c c u r r i n g

- Natural Gas

- Methane from Coal Mines

Manufactured from Solid Fuels

1 Wood Gas 2 Coal Gas

3 Producer Gas 4 Water Gas

5 Blast Furnace Gas

Manufactured from Petroleum

- Refinery Gas

- Liquefied Petroleum Gas ( L P G )

- Gases from Oil Gasification Process

Fermentation of Organic Wastes

- Methane Gas / Biogas

C L A S S I F I C A T I O N

(c) L O W B T U G A S

1 Producer Gas : 4 000 k J / n m 3

( based on Calorific Value )

 (a) H I G H B T U G A S

1 Liquefied Petroleum Gas : 1 25 610 kJ / nm3

2 Natural Gas : 35 170 – 38 102 kJ / nm3

(b) M E D I U M B T U G A S

1 Town Gas : 18 842 – 22 190 kJ / nm3

2 Industrial Fuel Gas : 9 210 – 12 980 kJ / nm3

• Paraffinic Hydrocarbon

• Principal Content – M e t h a n e

• High Btu gas ( C V : 35 000 kJ / nm3 & above )

N A T U R A L G A S

It occurs naturally in gas fields

and also in association with Crude

Petroleum in oil fields.

NATURAL GAS COMPOSITION

Components (% vol) Test Italian Russian Dutch AlgerianHelium - - 0.02 0.04 0.16Nitrogen 0.6 0.31 0.93 3.1 5.43Carbon Dioxide - 0.02 0.2 1.33 0.16Methane 90.2 99.59 97.32 90.3 83.66Ethane 8.5 0.04 0.94 3.89 7.75Propane 0.6 0.01 0.37 0.89 1.93Butane 0.1 - 0.14 0.26 0.64Pentane - - 0.04 0.08 0.15Hexane - 0.03 0.04 0.11 0.1

Density (kg/m3) 0.78 0.72 0.74 0.8 0.84Calorific Value

(MJ/m3) 38.4 35.8 36.1 36.3 37.9(MJ/kg) 49 49.7 48.4 45.6 47.1

Wobbe Index 94.4 48 47.8 46.3 47.1Methane Number 75 98 90 80 70H/C Ratio 3.82 4 3.95 3.86 3.73Air / Fuel Ratio

Stoichiometric (m3/m3) 10.22 - - - -(kg/kg) 16.86 17.12 16.81 15.68 15.49

Inert Mass 1 0.6 2.1 8.2 8.5

Incr

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0

10

20

30

40

ECE R49Duty Cycle

RefuseCollection

Bus Truck Average

ENERGY CONSUMPTION DIESEL vs NATURAL GAS

LOWER CALORIFIC VALUE AND DENSITY OF DIFFERENT FUELS

Lower calorific value Density

Fuel MJ/kg MJ/dm3 kg/dm3

Gasoline 40 29.9 0.748

Diesel Fuel 43 36 0.840

Methanol 20 16 0.794

Ethanol 27 21 0.792

Natural Gas 200 bar 50 6.3 0.128

Hydrogen 200 bar 120 1.9 0.016

Hydrogen 700 bar 120 5.0 0.042

Liquid Hydrogen 120 8.5 0.071

Biodiesel 37 33 0.88

Rape Seed Oil 38 35 0.92

NATURAL GAS ENGINE

• COMPRESSION IGNITION OF A NATURAL GAS/AIR – MIXTURE NOT FEASIBLE (TO HIGH AUTOIGNITION TEMPERATURE)

• DUAL FUEL OPERATION ALLOWS ‘DIESEL-LIKE‘ COMPRESSION RATIOS, BUT TWO COMPLETE FUEL - AND FUEL STORAGE - SYSTEMS ARE REQUIRED COMPLICATED OPERATION.

• NATURAL GAS TO BE USED IN SPARK IGNITION ENGINES EITHER WITH ONE OF THE FOLLOWING GAS ADMISSION SYSTEMS– SINGLE POINT– MULTI POINT – DIRECT INJECTION

NATURAL GAS ENGINE

• NATURAL GAS ENGINES SUITABLY APPLICABLE FOR CITY BUSES, DELIVERY VEHICLES AND GARBAGE COLLECTING VEHICLES AS WELL AS STATIONARY APPLICATIONS (GEN SETS, ETC).

• DUE TO FUEL STORAGE (COMPRESSED NATURAL GAS) NOT SUITED FOR LONG - DISTANCE HAULAGE

• IT WAS SUGGESTED TO ‘ENTER THE HYDROGEN USAGE‘ BY USING A MIXTURE OF NATURAL GAS AND HYDROGEN IN ROAD VEHICLES. THIS COULD BE DONE TECHNICALLY BUT WILL HAVE NEGATIVE EFFECT ON FUEL COST.

EMISSIONS COMPARED TO EUROPEAN STANDARDS

FUEL STORAGE RATIO - CNG

200 bar

200 bar

200 bar

200 bar

200 bar

11 55

Diesel

FUEL STORAGE RATIO - LNG

Diesel

= 0.83 kg/litre

-162OC

= 0.35 kg/litre

11 22

• Combustible gaseous mixture obtained

by blowing of air through an incandescent

bed of Solid Carbonaceous fuel

• Plant in which it is made is called as

GASIFIER• It is a fuel of low calorific Value

mainly containing C O & N 2

P R O D U C E R G A S

• Bituminous coal, anthracite and coke

are used as the raw material in gas producers.• With minor variations, Peat & Lignite can also be used.2 C + O2 + 3.76 N 2 2 C O + 3.76 N 2

- 5 8 7 3 0 kcal

M E R I TS1 G A S E O U S F U E L 2 C H E A P3 E A S E O F P R O D U C T I O N

Most widely used industrial fuel gas wherecheap solid fuels are abundant.

principal component

1 If air alone - (i) CO

- (ii) N2

2 If air + steam - (i) CO

- (ii) N2

- (iii) H2

C O M P O S I T I O NComposition % by volume

Produces Gas % by volumeMixed Blast With

Coal Coke Anthracite

CO2 4 . 0 5 . 0 6 . 0Cm Hm ( unsaturated ) 0 . 4 - -O2 - - -CO 2 9 . 0 2 9 . 0 2 6 . 0H2 1 2 . 0 1 1 . 0 1 7 . 0CH4 2 . 6 0 . 5 1 . 2N2 5 2 . 0 5 4 . 5 4 9 . 8Gross CV, kJ / nm3, dry 6500 5550 6000Specific gravity ( air = 1 ) 0 . 8 7 0 . 9 0 0 . 8 5Advantages

(i) Cheapness (ii) Ease of Production

(i) Low Calorific Value : 4500 kJ / nm3

( producer gas is a mixture of 33 % CO & 67 % N2 )

(ii)Low Cold Gas Efficiency < 7 0 %

(iii) 3 0 % of heating value of carbon is

liberated during the reaction. This

causes local heating & ash fusion.

D E M E R I T S

B L A S T F U R N A C E G A S

Blast furnaces may be regarded

as gas producers in which a few

other reaction take place in

addition to the usual producer

reactions.

The resultant gas has higher C O

and lower H2 content.

In Blast Furnaces combustion

gases raise thro’

the descending burden of coke,

ore & flux

Carbon Reduces C O 2 t o C O &

Decomposes Steam to H 2 and C O

Resultant gas known as Blast

Furnace Gas leaves the furnace at 2 0

0 0 C

C O M P O U N D % by vol.

C O 2 1 1C O 2 7H 2 2N 2 6 0

C O M P O S I T I O N

C V = 3 5 0 0 kJ / nm3

Gas Yield 2 4 0 0 nm3 / ton of pig iron

Higher dust content 2 0 - 3 0 g / m3.

Due its low C V it is necessary to

preheat the gas before usage

2 0 % used for preheating the blast

8 0 % for

Steam Raising / Open Hearth Firing

/ Reheating Furnaces / Coke Ovens

I T I N C L U D E S

i) Gases obtained during distillation,

cracking and other processing of

petroleum and petroleum fractions.

ii) Contains paraffins like Methane,

Ethane & Olefins like Ethylene,

Propene, H 2 S , H 2 , etc.,

R E F I N E R Y G A S R E F I N E R Y G A S

C O M P O U N D %H 2 S 6 - 8H 2 6 - 8C H 4 8 - 1 0C 2 H 4 + C 2 H 6 8 - 1 2

C 3 H 6 + C 3 H 8 4 0 - 5 5C 4 H 8 + C 4 H 10 < 3 0

C O M P O S I T I O N

C V 8 5 0 0 0 kJ / nm 3

L I Q U E F I E D L I Q U E F I E D P E T R O L E U M G P E T R O L E U M G A S A S In the gaseous hydrocarbons, C3 & C4

compounds can be liquefied at room

temperature and it can be stored.

It is known as L P G

Prepared from Wet Natural Gas,

Associated Gas & Refinery Gas

Lighter grade

Composition

C3H8

+

C3H6

Butane & iso - butane < 10 %

Ethane & Ethylene < 2 %

Higher grade

Butane, iso butane & Butene = 80 – 90 %

Propane & Propene < 20 %

Ethane & Ethylene < 2 %

= 90 %

1 Domestic Cooking

Butane major component

Storage pressure 3 atm

2 Industrial Usage for Thermal

Propane major component

Storage pressure 10 atm

3 In IC Engines as fuel .

4 Refinery process in the production of

Petrochemicals.

A P P L I C A T I O N S

Carbonization of Wood

at 4 0 0 0 C

Gas yield

1 2 5 nm3 / ton of dry wood

W O O D G A S W O O D G A S

C O 2 - 2 0 %

C n H m - 5 %

N 2 - R e s t

C A L O R I F I C V A L U E

1 3 8 7 0 k J / m3

C O M P O S I T I O N

C O - 2 5 %

C H 4 - 1 4 %

H 2 - 2 0 %

HYDROGEN

• CAN BE USED IN I.C. ENGINES AND IN FUEL CELLS

• HYDROGEN IS NOT AN ‘ENERGY SOURCE‘ .... BUT AN ENERGY CARRIER WHICH HAS TO BE PRODUCED AND THIS REQUIRES ENERGY

• EU COMMISSION WANTS TO FORCE EUROPE INTO A HYDROGEN ECONOMY BY THE YEAR 2050

HYDROGEN

• PRODUCTION OF HYDROGEN BY:

- HYDROLYSIS WHICH SHOULD UTILISE REGENERATIVE ELECTRICITY (SUN, WIND, HYDRO, GEOTHERMAL)

- STEAM REFORMING OF NATURAL GAS OR GASOLINE

- THERMAL SPLITTING OF WATER IN A HIGH-TEMPERATURE NUCLEAR REACTOR

- COAL GASIFICATION AT 900 ºC

- HYDROGEN PRODUCTION FROM BIOMASS

HYDROGEN PRODUCTION USING SOLAR

It is a High Btu gas

Calorific Value

1 2 0 MJ / kg

P R O P E R T I E S

Self ignition temperature is

high.

Extremely clear fuel, less toxic

and no carbonization in the

Engine

It has a wider flammability

range and higher burning velocity.

Gaseous form eliminates the

problem of atomization,

evaporation, mixing and

recondensation.

It is about 2.7 times heavier than

gasoline when compared on

mass basis.

It produces less pollution, main

pollutants is Nox from Nitrogen – Air

Engines.

Cryogenics & Hydrogen bomb

production

It is the most suitable renewable fuel

substitute for gasoline from

technical angles

P R O B L E M S W I T H H Y D R O G E N F U E L

Storage of Hydrogen is a problem.

Although energy per unit weight is

quite high, energy per unit volume

is low.

Vehicle range is limited due to

bulkiness of high pressure tanks.

In case of leak Hydrogen is much

more keen to ignite than gasoline.

Higher diffusivity and great

buoyancy of Hydrogen imply rapid

dispersal into atmosphere.

In the case of liquid Hydrogen

spilling it is far less hazardous than

gasoline.

Contd…

T W O W A Y O F G E T T I N G G A S F R O M B I O M A S

S

BIO CHEMICAL CONVERSION

BIO METHANATION

GASIFICATION ANAEROBIC DIGESTION

It is a High Btu gas

Calorific Value 38 000 kJ / nm3

Composition

55 – 60 % = CH4

40 – 45 % = CO2

Applications

Domestic cooking.

IC Engines.

BIOGAS LANTERN

EMISSION DETAILS

S.No FUEL CO2 ,kg / MWh SOx ,gm / MWh

NOx ,gm /

MWh

1. Natural Gas 179 1 136

2. Kerosene 240 23 190

3. Oil 264 500 690

4. Gasoline 262 505 417

5. Diesel 271 860 570

6. Coal 328 1770 1910

7. Biomass 0 46 1140

EMISSIONS FACTOR (source: Environment Protection Agency, EPA., USA)