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This detailed analysis covers various aspects of coal utilization, including its composition, characteristics, and energy content. Learn about coal types, combustion performance, fuel preparation, and calorific value measurement methods.
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Analysis of COAL for UTILIZATION P M V Subbarao Professor Mechanical Engineering Department Knowledge to be Quasi-static while Destroying the Permanent Entropy Vehicles…..
Operational Issues Design Issues Thermal structures Slagging. Fouling &Erosion Combustion System Thermal Performance Fuel Preparation system Combustion performance Fuel Handling system Fuel & Air
Analysis of Coal • Proximate Analysis & Ultimate Analysis. • Proximate analysis - to determine the moisture, ash, volatiles matter and fixed carbon • Ultimate or elementary analysis - to determine the elemental composition of the coal
Additional Characteristics of Coal • Sulfur Content : Coal with sulfur > 5% is not recommended for combustion. • Weatherability : Weathering or Slacking Index. • An indication of size stability • Denotes the tendency to break on exposure to alternate wet and dry periods. • Weathering index is the percentage of of coal passing through a seive having 170 mm2 openings.
Additional Characteristics of Coal • Grindability Index : A measure of relative ease of grinding coals or the power required for grinding coals in a pulverizer. • GI = 6.93 W + 13 -- W is the weight of sample passing through 200 mesh size. • Important in milling of the coal to a P.F. size specification. • Burning Characteristics of Coal : Free burning coals and Caking Coals -- Caking index -- Pulverulent, sintered, weakly caked, caked and strongly caked. • Ash Fusion temperature -- The temperature where the ash becomes very plastic -- Design of ash handling system. -- Stoker furnace cannot use low ash fusion temperature coals.
Maximum Extra-somatic Energy Content of A Fuel • Obtained only thru Combustion. • Standard heat of combustion: • The energy liberated when a substance X undergoes complete combustion, with excess oxygen at standard conditions (25°C and 1 bar). • The heat of combustion is utilised to quantify the performance of a fuel in combustion systems such as furnaces, Combustion engines and power plants. • In industrial terminology it is identified as the Gross Heating (calorific) Value or Higher Heating (calorific) value. • In a general design calculations, only Net Heating (calorific) Value or Lower Heating (calorific) value is used.
Ranking of Coal Medium Volatile Bituminous Sub Bituminous (C ) High-Volatile (C ) Bituminous LowVolatile (C ) Bituminous Anthracite B A B A HV High Rank Low Rank
Analysis of Coal • The Energy content -- CFRI Formulae -- • Low Moisture Coal(M < 2% ) -- CV (Kcal/kg) = 71.7 FC + 75.6 (VM-0.1 A) - 60 M • High Moisture Coal(M > 2%) -- CV(kcal.kg) = 85.6 {100 - (1.1A+M)} - 60 M • Where, M, A, FC and VM denote moister, ash , fixed carbon and Volatile mater (all in percent), respectively.
Measurement of Calorific Value : Bomb Calorimeter : Control Mass
Thermodynamic Description of Bomb Calorimeter • It is a combination of two closed systems. • Bomb: Constant volume closed system: Interacts only with calorimeter. • Calorimeter: Outer constant volume closed system: • Interacts only with bomb. • Isolates entire system with ambience.
Energy Balance & Estimation of CV Who all accepted the Thermal energy (heat) liberated due to combustion?
Biochar Production at IIT Delhi Kiln Capacity:25 L, Efficiency:20-25% Feedstock: Leaf Waste, Operating Temperature<450° C