Fuels, their types and characteristics .pdf

Definition of fuel, classification of fuels, advantages and disadvantages of solid, liquid and gaseous fuels

1. Unit-1: Classification and
Properties of Fuels
Prepared by
Ankur Sachdeva,
Assistant Professor, ME

2. What is a Fuel?
•Fuelsarecombustible
substance,containingcarbon
asmainconstituents,whichon
properburninggiveslarge
amountofheat,whichcanbe
used economicallyfor
domesticandindustrial
purposes.
•Alternately,materialswhich
possesschemicalenergyis
knownasfuel.
•ForexampleWood,Charcoal,
coal,Kerosene,petroldiesel,
oilgasetc.
Ankur Sachdeva, AP, ME

3. Combustion of a fuel
•Duringtheprocessofcombustionofafuel,theatomofcarbon,
hydrogenetc.combinewithoxygenwithsimultaneousliberationof
Heatatrapidrate.
•Thisenergyisliberatedduetothe“rearrangementofvalence
electrons”intheseatoms,resultingintheformationofCompounds
likeCO
2andH
2O.
•Thesecompoundshavelessenergy(heatcontent)ascomparedto
reactants.
Ankur Sachdeva, AP, ME
FUEL + O
2 PRODUCTS + HEAT
More heat energy content Lesser heat energy content
C (s) + O
2(g) CO
2(g) + DH= -94.1Kcal/mole

4. Classification of Fuels
Ankur Sachdeva, AP, ME
➢Thesecanbeclassifiedbasedontheiroccurrenceand
physicalstate.
➢(a)Onthebasisofoccurrencetheyareoftwotypes:
PrimaryFuels:Fuelswhichoccurinnatureassuchare
calledprimaryfuels.E.g.,wood,peat,coal,petroleum,
andnaturalgas.
SecondaryFuels:Thefuelswhicharederivedfromthe
primaryfuelsbyfurtherchemicalprocessingarecalled
secondaryfuels.Example:coke,charcoal,kerosene,
coalgas,producergasetc.

5. Classification of Fuels
Ankur Sachdeva, AP, ME
➢On the basis of physical state these may be classified
as:
Solid Fuels: Wood, Peat, Lignite etc.
Liquid Fuels: Crude oil, Tar, Diesel, Petrol, Kerosene.
Gaseous Fuels: Natural gas, coal gas

6. Natural and Manufactured Fuels
Ankur Sachdeva, AP, ME

7. Solid Fuels
•Solidfuelsaremainly
classifiedintotwo
categories,i.e.
•(i)Naturalfuels,suchas
wood,coal,etc.
•(ii)Manufacturedfuels,
suchascharcoal,coke,
briquettes,etc.
Ankur Sachdeva, AP, ME

8. Merits & Demerits of Solid Fuels
•Thevariousadvantagesanddisadvantagesofsolidfuelsaregiven
below:
Advantages
(a)Theyareeasytotransport.
(b)Theyareconvenienttostorewithoutanyriskofspontaneous
explosion.
(c)Theircostofproductionislow.
(d)Theyhavemoderateignitiontemperature.
Disadvantages
(a)Theirashcontentishigh.
(b)Theirlargeproportionofheatiswasted.
(c)Theyburnwithclinkerformation.
(d)Theircombustionoperationcannotbecontrolledeasily.
(e)Theircostofhandlingishigh.
Ankur Sachdeva, AP, ME

9. Liquid Fuels
Ankur Sachdeva, AP, ME
Petrol
Diesel
Furnace Oil
Ethanol
Kerosene
Light Diesel Oil (LDO)

10. Merits of Liquid Fuels
Theliquidfuelscanbeclassifiedasfollows:
(a)Naturalorcrudeoil,and
(b)Artificialormanufacturedoils.
Advantages
(a)Theypossesshighercalorificvalueperunitmassthansolidfuels.
(b)Theyburnwithoutdust,ash,clinkers,etc.
(c)Theirfiringiseasier,andfirecanbeextinguishedeasilybystopping
liquidfuelsupply.
(d)Theyareeasytotransportthroughpipes.
(e)Theycanbestoredindefinitelywithoutanyloss.
(f)Theyarecleaninuseandeconomictohandle.
(g)Lossofheatinchimneyisverylowduetogreatercleanliness.
(h)Theyrequirelessexcessairforcompletecombustion.
(i)Theyrequirelessfurnacespaceforcombustion.
Ankur Sachdeva, AP, ME

11. Demerits of Liquid Fuels
Disadvantages
(a)Thecostofliquidfuelisrelativelymuchhigheras
comparedtosolidfuel.
(b)Costlyspecialstoragetanksarerequiredforstoring
liquidfuels.
(c)Thereisagreaterriskoffirehazards,particularly,in
caseofhighlyinflammableandvolatileliquidfuels.
(d)Theygivebadodour.
(e)Forefficientburningofliquidfuels,specially
constructedburnersandsprayingapparatusarerequired.
Ankur Sachdeva, AP, ME

12. Gaseous Fuels
Ankur Sachdeva, AP, ME
•A) Fuels naturally found in nature
-Natural gas
-Methane from coal mines
•(B) Fuel gases made from solid fuel
-Gases derived from coal
-Gases derived from waste and biomass
-From other industrial processes
•(C) Gases made from petroleum
-Liquefied Petroleum gas (LPG)
-Refinery gases
-Gases from oil gasification
•(D) Gases from some fermentation

13. Merits of Gaseous Fuels
•Gaseousfuelsoccurinnature,besidesbeingmanufacturedfrom
solidandliquidfuels.
Advantages:
(a)Theycanbeconveyedeasilythroughpipelinestotheactualplace
ofneed,therebyeliminatingmanuallabourintransportation.
(b)Theycanbelightedatease.
(c)Theyhavehighheatcontentsandhencehelpusinhavinghigher
temperatures.
(d)Theycanbepre-heatedbytheheatofhotwastegases,thereby
affectingeconomyinheat.
(e)Theircombustioncanreadilybycontrolledforchangeindemand
likeoxidizingorreducingatmosphere,lengthflame,temperature,etc.
(f)Theyarecleaninuse.
(g)Theydonotrequireanyspecialburner.
(h)Theyburnwithoutanysoot,orsmokeandashes.
(i)Theyarefreefromimpuritiesfoundinsolidandliquidfuels.
Ankur Sachdeva, AP, ME

14. Demerits of Gaseous Fuels
•Disadvantages
(a)Verylargestoragetanksareneeded.
(b)Theyarehighlyinflammable,sochancesof
firehazardsintheiruseishigh.
Ankur Sachdeva, AP, ME

15. SOLID FUELS

16. Properties of Solid Fuel
•Fixed Carbon
•Volatile Matter
•Ash Content
•Moisture Content
•Combustion
Characteristics
•Ignition Temperature
•Calorific Value
•Carbon Content
•Hydrogen Content
•Oxygen Content
•Sulphur Content
•Nitrogen Content
Ankur Sachdeva, AP, ME

17. Wood
•Woodhasbeenusedasa
fuelfromancienttimes.
•Domesticfuelusedin
tropicalcountrieswhere
forestareabundantand
otherfuelsarenoteasily
andcheaplyavailable.
•Duetolargescale
deforestation,woodisno
longerintheboilerused
forproducingsteam.
Ankur Sachdeva, AP, ME
Briquettes with hole
Solid Briquettes
Pellets

18. Wood
•Woodfuelcanrefertoseveralfuelssuchasfirewood,charcoal,wood
chipssheets,pellets,andsawdust.
•Theparticularformuseddependsuponfactorssuchassource,quantity,
qualityandapplication
•Woodisvegetabletissueoftreesandbushes.
•Itconsistsofmainlycellulartissueandligninandlesserpartsoffatand
tar,aswellassugar.
•Main combustible components: cellulose and lignin (compounds of
carbon, hydrogen and oxygen)
•Minor combustible components: resin and waxes.
Ankur Sachdeva, AP, ME

19. Constituents of Wood
•Freshlycutwoodcontains25-50%
moisture.
•Airdriedwoodcontainsabout10-
15%moisturecontent.
•Thecalorificvalueofair-dried
woodisabout3500-4500kcal/kg.
•Whenwoodburns,theash
contentislow,buttheoxygen
contentisveryhigh.Thismakes
evendrywoodafueloflow
calorificvalue.
•Woodcharcoalisobtainedby
destructivedistillationofwood.
•Themajoruseofwoodcharcoalis
forproducingactivatedcarbon.
Ankur Sachdeva, AP, ME

20. Composition of Air-Dried Wood
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21. Calorific Value of Wood
Ankur Sachdeva, AP, ME