,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Fuels and Combustion,1,Recommended Books,Fuels and Combustion;,M.L.Smith&K.W.Stinson,Fuels and Fuel Technology;,W.Francis&M.C.Peters,Fuel Solid,Liquid and Gaseous;,J.S.S.,Brame,&J.G.King,Hydrocarbon Fuels;,E.M.,Goodger,Coal Conversion Processes;,Stanley&Lee,Fuel Testing:Laboratory Methods in Fuel Technology;,G.W.,Himus,Methods of Analysis of Fuels and Oils;,J.R.Campbell,2,Fuel,A substance which produce heat either by combustion or by nuclear fission/fusion,3,Classification of Fuels,Fuels can be classified as solid,liquid and gaseous fuels.,Solid fuels,:,wood,coal,charcoal and coke,Liquid fuels,:petrol,kerosene,diesel,alcohol etc,Gaseous fuels,:methane,propane,butane,hydrogen,coal gas,gobar gas etc,4,Classification of Fuels,Primary Fuels:,Naturally occuing e.g.coal,wood,natural gas,Secondary Fuels,:,Which are derived from primary fuels e.g.kerosene,coke etc,Naturally occurring,Artificially prepared,5,Combustion,Combustion,is the conversion of a substance called a,fuel,into chemical compounds known as,products of combustion,by combination with an,oxidizer,.,The combustion process is,an,exothermic,chemical reaction,i.e.,a reaction that releases energy,?,6,Combustion,Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel(usually a hydrocarbon)and an oxidant accompanied by the production of heat or both heat and light,7,Combustion,Fuel,+,Oxidizer,=,Products of combustion,+Energy,Fuel?,Oxidizer?,Products of Combustion?,Incomplete,Combustion?,8,Basic Flame types,Premixed:,Fuel and oxidizer are mixed first and burned later,Non-premixed:,Combustion and mixing occur simultaneously,Fundamental Definitions,9,Combustion,Air-Fuel Ratio;A/F,Oxygen-Fuel Ratio;O/F,Stoichiometric,or,Theoretical A/F,Excess Air,%excess air=100(A/F),actual,-(A/F),theo,/(A/F),theo,120%of theoretical air?,Fuel-Rich flame:,If there is an excess of fuel,Fuel-lean flame:,if there is an excess of oxygen,10,Combustion,1 kg of C needs?kg of O2,1 kg of H2 needs?Kg of O2,1 kg of Sulphur needs?kg of O2,11,Combustion,Problem:,A fuel contains by mass 88%carbon,8%H2,1%S and 3%ash.Calculate the stoichiometric air/fuel ratio,.,Ans:?,12,Fundamental Definitions,Calorific value,Amount of heat librated by the combustion of unit quantity of fuel.kcal/kg,kcal/m3,Gross Calorific Value(G.C.V)or HCV,heating value measurement in which the product water vapour is allowed to condense,Net Calorific Value(N.C.V)or LCV,heating value in which the water remains a vapor and does not yield its heat of vaporization,HHV=LHV+(,m,water,/m,fuel,),water,13,Flash Point,The lowest temperature at which a liquid fuel gives enough vapours in air which produce a momentary flash when exposed to a flame,Firepoint,The lowest temperature at which a liquid fuel vapours in air produces a continuous flame when exposed to a flame,Fundamental Definitions,14,Density,Specific gravity,Viscosity,Pour Point,Carbon Residue,Fundamental Definitions,15,Theoretical Flame Temperature:,It is the temperature attained by the products of combustion of fuel when there is no loss of heat to the surroundings,Flue Gas:,It is the gaseous product of combustion of fuel,Fundamental Definitions,16,Coal,Origin of Coal,Coal has been formed by the partial decay of plant materials accumulated million of years ago and further altered by the action of heat and pressure,In situ Theory:,coal occupies the same site where the orignal palnts grew,Drift Theory:,plants were uprooted and drifted by rivers to get deposited,17,Coal classification,Peat:,Lignite:,soft coal and the youngest,sub-bituminous,Bituminous:,semi-bituminous:,Anthracite:,hard and geologically the oldest,composed mainly of carbon,18,Coal Analysis,Proximate analysis of coal,Determines only fixed carbon,volatile matter,moisture and ash,Useful to find out heating value(GCV),Simple analysis equipment,Ultimate analysis of coal,Determines all coal component elements:carbon,hydrogen,oxygen,sulphur,etc,Useful for furnace design(e.g flame temperature,flue duct design),Laboratory analysis,19,Proximate analysis,Moisture Content:,Moisture in coal must be transported,handled and stored,Since it replaces combustible matter,it decreases the heat content per kg of coal,Aids radiation heat transfer,1-2 gm 72 mesh coal at 105-110 C till constant weight,20,Proximate analysis,Volatile Matter:,Consist of CH,4,hydrocarbons,H,2,and CO,and incombustible gases like CO,2,and N,2,Proportionately increases flame length,and helps in easier ignition of coal,Sets minimum limit on the furnace height and volume,72 mesh coal 900-950 C for 7 minutes,21,Proximate analysis,Ash Content:,Ash is an impurity that will not burn,Reduces handling and burning capacity.,Increases handling costs.,Affects combustion efficiency and boiler efficiency,Causes clinkering,1-2 gm 72 mesh 800 C(burned),22,Proximate analysis,Fixed carbon:,Solid fuel left in the furnace a