-Ms. Neha Patni

DEFINITION: Any combustible substance which is obtainable in bulk, which may be burnt in atmospheric air in such a manner that the het evolved is capable of being economically used for domestic and industrial purposes for heating and generation of power.

FUEL + O2 Products + Heat

The composition of coal varies according to the degree of coalification.

In order to compare the coals for the consumer, prize fixation and many other factors ,the analysis of coal is carried out

Coal analysis are of two types :

1. Proximate analysis

2. Ultimate analysis

1.SUITABILITY: For instance , coke made out of bituminous coal is most suitable for blast furnace , inspite of the fact that charcoal or anthracite

may also be used.

2.COST: The fuel should have a low cost and on prolong storage it should not change its properties significantly.

3.CALORIFIC VALUE: The fuel must possess high calorific value (heat per unit mass or volumes)and produces no hazardous gases which might

pollute the atmosphere.

4.IGNITION TEMPERATURE OR KINDLING TEMPERATURE: The minimum temperature at which the substance ignites and burns without further addition of heat from outside . Fuel should possess a moderate ignition

temperature . Too high ignition temperature causes difficulty in kindling while too low ignition temperature may create safety problems during storage , transport and use of the fuel . The presence of moisture and foreign material in the fuel always decreases the ignition temperature.

5.Flame temperature: The highest temperature at which an substance can be heated by flame is called flame temperature . The flame temperature

generally increases with the increases in the number of combustibles.

6.MOISTURE: It should be very low. High moisture content lowers the effective calorific value of the fuel.

7.NON COMBUSTIBLE MATTER CONTENT: The non combustible matter forms clinkers after combustion and it reduces the heating value and involves the cost of disposal after the combustion.

8.VELOCITY OF COMBUSTION: Velocity of combustion should be moderate. Too high velocities of combustion are not required whereas too low velocities causes loss of heat due to radiation.

9.Control of the process: The fuel should be such that its combustion can easily be controlled i.e. It can be easily started or stopped.

10.Ash: It should produce minimum quantity of ash upon combustion . The Higher proportion of ash may have lower calorific values.

11.Sulphur and Oxygen: The fuel should have minimum quantity of sulphur and oxygen because higher sulphur contents may create corrosion , while oxygen decrease ignition temperature .

12.Safety: It should be safe while transporting and storage.

13.Production of side products: It should not produce any undesirable products(i.e. Noxious gas and pollutants) upon combustion which are harmful to the atmosphere.

Characteristics of a good fuel (REVISION)

Calorific value

G.C.V. (Gross calorific value) or H.C.V. (High calorific value)

Definition : “Total amount of heat liberated when unit mass bond and products are cool down. They are not allow to escaped.”

G.C.V = N.C.V + LATENT HEAT.

N.C.V (Net Calorific value ) or L.C.V (Low calorific value)

Definition : “ Total amount of heat liberated when unit mass of fuel bond and products are allowed to escaped.”

GCV =

1\100 (8080C + 34500(H –O\8)+2240S)

NCV=[GCV – 0.09 H * latent heat of

condensation]

Where ,C= percentage of carbon

H=percentage of hydrogen

O=percentage of oxygen

S=percentage of sulphur

- Most useful compound to human kind

Peat

Lignite

Sub-bituminous

Bituminous

Anthracite

Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions.In its dehydrated form, peat

is a highly effective absorbent for fuel and oil spills on land and water

Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation

Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Important source of light for the chemical synthesisindustry.

Bituminous coal, dense sedimentary rock, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke

Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania

Proximate analysis is a empirical rather than true analysis.

It includes the determination of the following:

1. Moisture content

2. Volatile matter

3. Ash

4. Fixed carbon

Moisture content :

Moisture content should be low.Reason:

1. For every percent of moisture present 1% of heat is lost.

2. Increases transport cost.

However about 5-10% moisture is desirable as it produces a uniform fuel bed and less of fly ash.

Moisture content is determined by

1. Heating a known quantity of air-dried coal to 105-110 C for an hour.

2. It is cooled and then weighed.

3. Loss in weight of coal is reported as moisture content on percentage basis

Percentage moisture= (W-w) x 100 /W

Where, W=weight of sample before heating

w= weight of sample after heating

VOLATILE MATTER :

Volatile matter consists of a mixture of gaseous and liquid products resulting from the thermal decomposition of coal.Eg : H2,CO,CH4

It does not include moisture of coal.Volatile matter must be low.Reason:1. A high percentage of volatile matter indicates that

a large part fuel is burnt as a gas which may escape unburnt.

2. Higher volatile matter means more smoke and more pollution.

%C= (12/44)*(x/w)*100

%H=(2/18)*(y/w)*100

(where,

x=weight of CO2 absorbed

y=weight of H20 absorbed

w=weight of original sample)

It is determined by:1. Heating a known weight of moisture free coal at

around 950 C for 7 minutes.2. It is then cooled.3. Loss in weight is reported as volatile matter.Percentage volatile matter =(x-y) X 100 / w

where x=weight of the sample before heating

y=weight of sample after heating

ASH CONTENT :

Ash usually consists of silica, alumina, iron oxide and small quantities of lime, magnesium etc.

Ash content should be low.

Reason:

1. It reduces calorific value.

2. In furnace grate, the ash may restrict the passage of air and lower the rate of combustion.

It is determined by :

1. Heating a known weight of coal sample at 750 C for about 1 hour.

2. The remaining mass is then cooled and weighed.

3. The remaining mass in terms of percentage is reported and ash content.

Percentage ash= z X 100/ W

Where z=weight of residue left

W=weight of coal sample.

FIXED CARBON :

Fixed carbon content must be high.

Reason :

1. Higher fixed carbon content means greater calorific value.

Percentage of fixed carbon =

100 – [% moisture + %volatile matter + %ash]

The ‘ultimate analysis’ gives the composition of the biomass in weight percentage of carbon, hydrogen and oxygen (the major components) as well as sulphur and nitrogen (if any).

Helps determine if the fuel is good for a particular application (as opposed to proximate analysis that gives only the general usability of a fuel).

Also called ‘Elemental Analysis’.

Required for detailing and accurating heat balance for equipments in which coal is used

Useful in estimating calorific value of coal

Used in designing furnaces

The ultimate analysis determines the elemental analysis of the fuel sample like :

1. Carbon

2. Hydrogen

3. Sulphur

4. Nitrogen

5. Oxygen.

A known mass of organic compound is heated in the presence of pure oxygen. The carbon dioxide and water formed are collected and weighed. The percentages of carbon and hydrogen in the compound are calculated from the masses of carbon dioxide and water.

Leibig’s Apparatus

PROCEDURE :

A known amount of coal( x gm) Is taken in a combustion tube and burnt in excess of oxygen(no C02 or moisture).The hydrogen and carbon are converted into H2O and CO2.

C(s) + O2(g) CO2(g)

12gm 2 X 16 gm 44gm

H2 + ½O2(g) H2O

2gm 16gm 18gm

The other oxidation products sulphur(S) and chlorine(Cl) are also obtained which are trapped by silver gause heated at 800-850 C, while CO2 and H2O are absorbed in pre-weighed KOH solution and anhydrous CaCl2.

2KOH +CO2K2CO3+ H2O

CaCl2 + 7H2O CaCl2.7H2O

Let,

Weight of coal sample=w gm

Increase in weight of CaCl2=y gm

Increase in weight of KOH=x gm

44 gm of CO2 = 12 gm of C

Y gm of CO2 =(12/44) X y gm of carbon

Therefore, % carbon=(12/44) X (x X 100)/w

Similarly, % hydrogen= (2/18) X (y X100)/w

Greater the percentage of carbon, greater the calorific value

Higher percentage of carbon reduces the size of the combustion chamber required.

Higher percentage of hydrogen also increases the calorific value of the fuel.

The nitrogen content present in coal is estimated by Kjeldahl’s method.

Procedure: A known weight of coal sample long with K2SO4 + HgSO4

is taken which acts as a catalyst is heated with conc. H2SO4.

Nitrogen present gets converted into (NH4)2SO4. The contents are then transferred into a round bottom flask

and the contents are then heated with excess NaOH. The NH3 gas thus liberated is absorbed in a known volume

of standard acid. The unused acid is then determined b titrating with NaOH. From volume of acid used by NH3 , nitrogen content can be

calculated.

(NH4)2SO4 + 2NaOH Na2SO4 + 2NH3 + 2H2O

NH3 + H2SO4 (NH4)2SO4

Let, weight of coal sample = W gmVolume of acid used= V1 mlNormality of the acid = N1

V1 ml of N1 acid= V2 ml of N2 NH3

V2 ml of 1N NH3= V1 X N1 ml of acidBut 1000 ml of 1 N ammonia solution= 17g of

NH3=14g of nitrogenTherefore, V2 ml of 1 normal ammonia solution

= (14 X N1 X V1)/1000Percentage nitrogen=(1.4 X N1 X V1)/W

Procedure: Sulphur present in the coal is oxidized by fuming

nitric acid and sulphuric acid. The sulphurinc acid is precipitated as BaSO4 by

addition of BaCl2. The precipitate of BaSO4 is filtered and heated to a

constant weight. From the weight of BaSO4,sulphur content is

calculated.Let, Weight of coal sample= W gm

the mass of precipitate = x gm233 gm of BaSO4 = 32 g of sulphurW gm of BaSO4 = (32/233) gmPercentage of sulphur = (32/233) X (x/W) X 100

ASH:-

It is determined in the same way as in proximate analysis.

DETERMINATION OF OXYGEN:

The percentage of oxygen can be calculated by deducting the percentage of all the element present in the coal from 100 by using following formula.

% of oxygen = 100 – [% C + % H +% N + % S + % Ash]

Significance :

Less is the oxygen content better is the coal.

Oxygen is in combined form with hydrogen in coal and thus hydrogen available for combustion is lesser than the total hydrogen present.

PROXIMATE ANALYSIS : REVISION

Ultimate analysis : Revision

The mixture of Carbon dioxide, Carbon monoxide and Oxygen releasing out of combustion chamber is known as flue gases.

Analysis of flue gases gives idea regarding the efficiency of the combustion process.

1. More carbon monoxide content in flue gases indicate that oxygen supply is less and combustion is Incomplete.

2. If there high percentage of oxygen , it indicates that combustion is complete but the supply of oxygen is excessive.

3. If there is high percentage of carbon dioxide , it indicates proper combustions of fuel and adequate supply of oxygen.

E -Entrance for flue gas.

U -contains glass wool for,

retaining moisture and smoke.

V -three way stopcock.

S1,s2,s3 -are stopcocks connecting

to bulbs b1,b2,b3

respectively.

FLUE GAS ANALYSIS

by ORSAT’s APPARATUS

Absorption Bulb

Solution Filled Function

B1 Ammonical Cuprous Chloride(100 gm CuCl + 125 ml liq. NH3

+75 ml H2O)

It can absorb CO,O2,CO2

B2 Alkaline Pyrogallic acid(25 gm Pyrogallic acid

+ 200 gm KOH + 500 ml H2O)

It can absorbCO2,O2

B3 Potassium Hydroxide Solution(200 gm KOH + 500 ml H2O)

It absorbCO2

Different Solutions filled in bulbs of Orsat Apparatus

Working of Orsat Apparatus

1. Apparatus is thoroughly cleaned. Stoppers are cleaned , greased

and tested for air tightness. Solutions are filled in bulbs as per

above. The jacket and separating funnel are filled with water.

2. Close S1,S2,S3 and open valve V to connect the atmosphere and

separating funnel and fill water in gas burette.

3. Now close V and open S3 and lower down the separating

funnel

so water will run to B3 and suck the required quantity of water

and close the valve.

4. Similarly other two bulbs are also brought to the required mark.

5. Open valve V to connect B1 and atmosphere , adjust

separating

Funnel till glass bulb is filled with water. Connect V and E and

allow

the Gas to be analysed in glass tube.

6. In this way gas is expelled , suck again to remove trace

amount of air

in glass tube and untill exactly 100ml of gas at atmosphere is

collected.

7. Close V and open S3 ,raise level of SF to get gas in B2,lower the

SF to

Get gas in GB and repeat till complete absorption of CO2 in

KOH .

8. Lower SF until solution in the bulb remains at the fixed mark

and then

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BIODIESEL

ETHANOL

HYDROGEN

METHANOL

NATURAL GAS

CNG

LNG

LPG

Biodiesel is a domestically produced, renewable fuel that can be manufactured from vegetable oils, animal fats, or recycled restaurant greases.

Biodiesel is safe, biodegradable, and reduces airpollutants such as particulates, carbon monoxide, hydrocarbons, and air toxics.

Biodiesel can also be used in its pure form but it may require certain engine modifications to avoid maintenance and performance problems and may not be suitable for wintertime use.

Need to heat storage tanks in colder climates to prevent the fuel from gelling

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IT IS ALCOHOL BASED FUEL

PRODUCED BY FERMENTING

AND DISTILLING STARCH

CROPS.

ETHANOL PRODUCED FROM

CELLULOSIC BIOMASS SUCH

AS TREES AND GRASSES IS

CALLED AS BIOETHANOL.

E85,E95,E10 ARE USED AS

FUELS IN VEHICLES.

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Gasoline with ethanol is still gasoline. It's not an alternative fuel.

An increasing number of new vehicles can use E85 (15% gasoline,

85% ethanol), which is an alternative fuel.

Methanol, also known as wood alcohol, can be used as an alternative fuel in flexible fuel vehicles that run on M85

The benefits include lower emissions, higher performance, and lower risk of flammability than gasoline

Methanol can easily be made into hydrogen for hydrogen fuel cell vehicles in the future.

Methanol is extremely corrosive, requiring special materials for delivery and storage.

H2 HAS BEEN USED EFFECTIVELY IN A NUMBER OF INTERNAL COMBUSTION ENGINE VEHICLES AS PURE H2 MIXED WITH NATURAL GAS.

H2 AND O2 FROM AIR FED INTO A PROTON EXCHANGE MEMBRANE(PEM) FUEL CELL”STACK” PRODUCE ENOUGH ELECTRICITY TO POWER AN ELECTRICITY TO POWER AN ELECTRIC AUTOMOBILE,WITHOUT PRODUCING HARMFUL EMISSIONS.

TWO COMMON METHODS TO PRODUCE H2 ARE:

(I)STEAM REFORMING OF NATURAL GAS

(II)ELECTROLYSIS OF WATER

IT HELPS IN:

(I)ENERGY SECURITY

(II)GLOBAL CLIMATE CHANGE

(III)AIR QUALITY

◦ Individual fuel cells can be placed in a series to form a fuel cell stack◦ The stack can be used in a system to power a vehicle.◦ Automakers and experts speculate that a fuel cell vehicle will be commercialized soon.◦ Fuel cell buses are currently in use in North and South America, Europe, Asia and Australia.◦ Trains, planes, boats, scooters, forklifts and even bicycles are utilizing fuel cell technology as well.

NATURAL GAS ARE DOMESTICALLY

PRODUCED,HAVE CLEAN BURNING,AND HAS

LESS HARMFUL EMISSIONS.

IT IS THE MIXTURE OF HYDROCARBONS

MAINLY CH4 AND IS PRODUCED EITHER

FROM GAS WELLS OR IN CONJUCTION WITH

DRUDE OIL PRODUCTION.

SMOG PRODUCING GASES SUCH AS CO AND

Nox ARE REDUCED BY 90% AND 60%.

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Still a major contributor, despite reductions in new vehicle emissions achieved over the last decade

CO

NOx

Lead

VOCs

CO2

Particulates

79%

53%

13%

44%

33%

25%

SO2

7%

LNG IS ALMOST PURE METHANE AND BECAUSE IT IS A LIQUID HAS AN ENERGY STORAGE DENSITY MUCH CLOSER TO GASOLINE THAN CNG.

IT IS TYPICALLY USED IN HEAVY-DUTY APPLICATIONS SUCH AS TRANSISTS BUSES,HEAVY DUTY,LONG-HAUL TRUCKS OR LOCOMOTIVES.

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CNG is made by compressing natural gas which is mainly

composed of methane, to less than 1% of the volume it

occupies at standard atmospheric pressure.

CNG HAS LOW HYDROCARBON EMISSIONS AND

VAPOURS ARE NON-OZONE PRODUCING.

CNG IS 70%-90% METHANE

10%-20% ETHANE

2%-8% PROPANE AND DECREASING

QUANTITES OF HCs UP TO PROPANE.

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ALSO KNOWN AS BOTTLED GAS OR

REFINERY GAS WHICH IS OBTAINED AS A

PRODUCT DURING THE CRACKING OF HEAVY

OILS OR FROM NATURAL GAS IS

PREDOMINANTELY PROPANE WITH iso-

BUTANE AND n-BUTANE.

LPG CONSISTS OF HYDROCARBONS OF SUCH

VOLATILITY THAT THEY CAN EXIST AS GAS

UNDER ATM. PRESSURE BUT CAN BE

READILY LIQUEFIED UNDER PRESSURE.

Propane or liquefied petroleum gas (LPG) is a

popular alternative fuel choice for vehicles because there is

already an infrastructure of pipelines, processing facilities, and

storage for its efficient distribution.

LPG produces fewer vehicle emissions than gasoline.

Propane is produced as a by-product of natural gas processing

and crude oil refining.

The cost of a gasoline-litre equivalent of propane is generally

less than that of gasoline.

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CNG

More economical

Kit more expensive

More wear and tear on

engine

Safer in case of leakage-

lighter than air

Does not contaminate and

dilute the crankcase oil

LPG

Higher Calorific Value

Easily Available

Wears out piston heads with

heavy loads

Stored at lower pressures

Non-corrosive and free of

tetra-ethyl lead or any

additives

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