Post on 01-Sep-2014
description
COAL
Chemical Structure of Coal(Depending upon source, structure may be widely different)
Anthracite Coal Carbon 92-98%
Coal is a stored fossil fuel, occurring inlayers in the earth’s crust, which hasbeen formed by the partial decay ofplant materials accumulated millions ofyears ago and further altered by theaction of heat and pressure.
COAL : DEFINITION
COAL FORMATION
IN SITU THEORY DRIFT THEORY - Flood /Tsunami type wave
(velocity 800 km/h) 300 million of years (earth is 4.6 billion years old) 15-20 m OF PLANT MATERIAL= 1 m OF COAL SEAM In INDIA 30 m seam of coal has been found
THEORIES OF COAL FORMATION
450-600 m of plant material might have accumulated at that place.(Taipei 101:509 m tallest building in world)
COALIFICATION COAL % C C H O Heating
value(MJ/kg)
CelluloseWoodPeatLigniteBrown coalBituminous coalAnthraciteGraphite
44.550.059.961.869.578.791.0100
100100100100100100100100
13.912.010.07.87.96.04.70.0
11188575436215.20.0
-19.7718.6620-2527.2032.1032.5632.91
Time
COAL RANKS 1.Peat: starting point of coal formation
does not come in the category of coalCarbon: 60-64%; Oxygen:35-30%
2. Lignites: mark the transition of peat to coalCarbon: 60-75% ; Oxygen: 30-20%Colour: black, brown, earthyDisintegrate very easilyBriquetting is doneNeyveli Lignite Corporation, Chennai, TamilnaduPossesses largest reserves of Lignite in IndiaElectricity generation: 2490 MW
COAL RANKS contd…3. Bituminous coals
Sub-bituminous: Between lignites and bituminous Carbon: 75-83% ; Oxygen: 20-10%No caking power (Briquettes can not be made)
Bituminous: black and banded Industrial and domestic usageCarbon: 75-90%: Oxygen:10-5%Semi-bituminous: Between bituminous and anthraciteMetallurgical coke formationCarbon: 90-93%; Oxygen:4-1%
COAL RANKS contd…4. Anthracites
Highest rank of coalExtreme of metamorphosis from the original plant materialCarbon: 93+%: Oxygen: 2-1%Caking power zero
Unusual coalsCannels: found rarely; high hydrogen content: burn with smoke and bright flame; does not fall in any category.Torbanites: fine grained coal, named after Torbane Hill of Scotland, rich in paraffin oil.
Unusual Solid Fuel (Methane Clathrate)
Burning Ice 1 mole methane in 5.75 mole
H2O Available in Deep sea (methane
from trench + cold water + high pressure) and at the lower ice layer in Antarctica
It is expected that 15,000 Gt (21×1015 m3) of methane is available in this form (as compared to 1,000 Gt of Coal)
Country Million tonnes % of world production
China 2380 39.75
USA 1053.6 17.59
India 447.3 7.47
Australia 373.8 6.24
South Africa 256.9 4.29
Canada 62.9 1.05
United Kingdom 18.6 0.31
Pakistan 4.3 0.07
Japan 1.3 0.02
Total of the world 5,986.90 100
WORLD PRODUCTION OF COAL IN YEAR 2006
WORLD PRODUCTION OF COAL IN YEAR 2006
China
USA
India
Australia Japan
Pakistan Canada South Africa
United Kingdom
WORLD TOP TEN COAL PRODUCING AND CONSUMING COUNTRIES
1 quadrillion=1000 trillion1 Btu=1.055 kJ
Type of coal TOTALRESERVE
PROVED RESERVE
INDICATEDRESERVE
INFERREDRESERVE
COKING 32 17 13 2NON-
COKING 223 81 105 36
TOTAL 255 98 118 38
COAL RESERVES OF INDIA
Source: MoC
Years to consume this coal with present rate: 600
(As on 1.1.2007 in billion tonnes)
Cokes are the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal.
State Proved Indicated Inferred Total % of totalJharkhand 36881 31094 6339 74314 29.11Orissa 17464 30239 14296 61999 24.29Chhattisgarh 10182 26826 4443 41451 16.24West Bengal 11454 11810 5071 28335 11.10Madhya Pradesh 7584 9259 2934 19777 7.75Andhra Pradesh 8475 6328 2658 17461 6.84Maharashtra 4856 2822 1992 9670 3.79Uttar Pradesh 766 296 0 1062 0.42Meghalaya 118 41 301 460 0.18Assam 315 27 34 376 0.15Bihar 0 0 160 160 0.06Arunachal Pdesh 31 40 19 90 0.04Sikkim 0 55 18 73 0.03Nagaland 3 1 15 19 0.01Total 98129 118838 38280 255247 100
COAL RESOURCES OF STATES IN MILLION TONNES Jan 1, 2007
Proved: boreholes (1200m deep) @ 400 mIndicated & Inferred: boreholes @ 1-2 km
Coking coal (carbon: 81-91%) Non-coking coal
GRADING OF INDIAN COAL
Grade Industry Ash %I steel <15II steel 15-18I washery* 18-21II washery* 21-24III washery* 24-28IV washery* 28-35
Grades of coking coal
* Washed Coal is used as fuel in thermal power plants
High ash content (up to 50%) Lower heating/calorific value Inferior quality but suitable for power gen.
GRADING OF INDIAN COAL
Grade UHV, kcal/kg Ash %A >6200 <13.56B 5600-6200 13.56-17.91C 4940-5600 17.91-22.69D 4200-4940 22.69-28.06E 3360-4200 28.06-34.14F 2400-3360 34.14-41.10G 1300-2400 41.10-49.07
Grades of non-coking coal
UHV:Useful Heating Value=8900-138×[ash% + moisture%]
Based on 6 % moisture content
Nationalization in 1971 Coal companies are paying the
royalty to states This varies from Rs 90-250/tonne The rate is dependent of coal
grade Rates are 16 August 2002 onwards
ROYALTY TO STATES
IMPORT OF COAL Coking and non-coking coals being imported
Year Coking Non-coking Total
1991/92 5.27 0.66 5.93
1996/97 10.62 2.56 13.18
2000/01 11.06 9.87 19.70
2003/04 12.99 8.69 21.68
2005/06 16.89 21.70 38.59
2006/07 22.00 23.00 45.00
In million tonnes
Proximate analysis Ultimate analysis Heating/calorific value
ANALYSIS OF COAL
1. Moisture content: 105 -110 oC
2. Volatiles: 925±15 oC for 7 min time (with lid)
3. Fixed carbon: by difference
4. Ash: 800±15 oC (without lid)
PROXIMATE ANALYSIS
IS:1350-I (1984)
REPORTING: AS RECEIVED BASIS, MOISTURE FREE BASIS/DRY BASIS OR DRY ASH FREE BASIS
A sample of finely ground coal of mass 0.9945 g wasplaced in a crucible of 8.5506 g in an oven, maintained at105 oC for 4.0 ks. The sample was then removed, cooled ina dessicator and reweighed; the procedure being repeateduntil a constant total mass of 9.5340 g was attained. Asecond sample, of mass 1.0120 g in a crucible of mass8.5685 g was heated with a lid in a furnace at 920 oC for420 s. On cooling and reweighing, the total mass was9.1921 g. This sample was then heated without a lid in thesame furnace maintained at 725 oC until a constant totalmass of 8.6255 g was attained. Calculate the proximateanalysis of the sample and express the results on “assampled” and “dry, ash-free” basis.
EXAMPLE OF PA
MOISTURE (from first sample)mass of sample = 0.9945 g mass of dry coal = (9.5340-8.5506) = 0.9834 gmass of moisture = (0.9945-0.9834) = 0.0111 g% moisture = 0.0111 × 100/0.9945
= 1.11 %
EXAMPLE OF PA contd..
ASH (from second sample)Mass of sample = 1.0120 gMass of crucible = 8.5685 g
Heating up to 920ºC in absence of air removes volatile matters, subsequent heating up to 725ºC in presence of air burns all fixed carbon of the sample leaving behind ash in the crucible.
Mass of ash (remnant in crucible) = (8.6255 - 8.5685)= 0.0570 g
% ash = 0.0570 × 100/1.0120 = 5.63 %
VOLATILE MATTERInitial mass of sample + crucible = 1.0120 + 8.5685 = 9.5805 gFinal mass after heating up to 920ºC (without air) = 9.1921 gMass of volatile matter + moisture = Initial – Final mass
= (9.5805-9.1921) g= 0.3884 g
% Moisture + Volatiles = 0.3884 x 100/1.0120= 38.3794 %
% VOLATILE MATTER = 38.3794 – 1.11 (% Moisture)= 37.26 %
EXAMPLE OF PA contd..
FIXED CARBON% FC = 100 - % VM - % ash - % moisture
= 100 – 37.26 - 5.53 - 1.11= 55.98 %
Proximate analysis as received basisMoisture : 1.11 %Ash : 5.63 %Fixed carbon : 55.99 %Volatile matter : 37.26 %
Proximate analysis on dry, ash free basisMoisture + ash = 1.11 + 5.63 = 6.74%Fixed carbon: 55.99x100/(100-6.74) = 60.04 %Volatile matter: 37.26x100/(100-6.74) = 39.95 %
EXAMPLE OF PA contd..
1. Carbon2. Hydrogen3. Oxygen4. Sulfur :0.5-2.50 %5. Nitrogen :1.0-2.25 %6. Phosphorus :0.1%;Blast Furnace: <0.01 %7. Chlorine
ULTIMATE ANALYSIS
IS:1350- IV (1974)
Mercury: A big problem from NTPC plants (up to 0.3mg/kg)
1. Calculated from proximate analysis2. Calculated from ultimate analysis3. Experimental determination
HEATING VALUE
1. Gross/High heating value
2. Useful/low heating value
Hydrogen Water (gas/vapor or liquid phase)
Carbon Carbon Dioxide (gas phase)
Latent heat of vaporization of water: 2.26 MJ/kg
1. Calculated from proximate analysis
HEATING VALUE
TAYLOR AND PATTERSON RELATIONSHIPHV=4.19 (82FC+ a VM) kJ/kgWhere FC and VM are on dry ash free basis and a is an empirical constant which depends on the VM content of coal.
VM 5 10 15 20 25 30 35 38 40
a 145 130 117 109 103 98 94 85 80
8090
100110120130140150160170
0 10 20 30 40
2. Calculated from ultimate analysis
HEATING VALUE
DULONG FORMULAHV=338.2C+1442.8(H-O/8)+94.2S kJ/kgWhere C, H, O and S are the % of these elements on dry ash free basis.
3. Experimental determination: Bomb calorimeter
HEATING VALUE
IS:1350-II (1970)
solid /liquid samples can be analyzed 1 g air dried sample is burnt in a bomb in oxygen
atmosphere rise in temperature gives the heat liberated and
heating value is determined after doing the corrections for resistance wire and thread.microprocessor based bomb calorimeters are now
available
BOMB OF CALORIEMETER
VARIOUS COMPONENTS OF BOMB CALORIMETERIC EQUIPMENT
ROUTES OF GENERATION OF HEAT AND POWER FROM COAL
1. Direct use as thermal energy in heating processes, furnaces and domestic heating by open fires
2. Transfer of the heat to a thermal fluid and application of the latter for heating and power e.g., steam for heating in process industry, central heating and electricity generation by steam turbines
3. Gas turbine route to electricity generation
4. Conversion to gas/liquid fuels and subsequent usage in IC engines/turbines (gas/steam)
ROUTE I (Direct Heating)
Domestic cooking (Chula at tea stalls, dhaba, bakery)
Space heating (Fireplace)
Lime and brick kilns (Direct heating of stack)
Ceramic industry (Oven/Furnace)
Generation of steam in a boiler Space heating by transferring heat of steam to air Process industry : Cogeneration is employed Utility services : steam turbines used
ROUTE II (Thermal Fluid)
GOVERNMENT ALLOWED ELECTRICITY GENERATION BY PRIVATE DEVELOPERSTariffingWheelingBanking
SUPERCRITICAL BOILERS: A RECENT CONCEPTCritical pressure: 218 bar (21.8 MPa); Critical temperature: 374oCMark Benson; in 1922 Patent was granted22 MPa pressure ; η= 1-T1/T2 ≈ 0.53
ROUTE II contd..
Coal
Hot air for spaceheating
Con
dens
ate
Steam
Alternator
Electricity to grid
Con
dens
ate
Steam
Air
to grid
Cogeneration
AlternatorSteam turbine
Heat exchanger
Boiler
Steam
Steamturbine
Steam
Process plant
Electricity
ROUTE III
Electricityto grid
Preheated air
Air
Turb
ine
exha
ust
CompressorGas turbine Alternator
Vent
Heat exchanger
Pulverizer
Coal
Combustion chamber
ROUTE III
Electricityto grid
Preheated air
Air
Turb
ine
exha
ust
CompressorGas turbine Alternator
Vent
Heat exchanger
Combustion chamber
Gasifier and gas cleaning unit
Coal
ROUTE IV (Pyrolysis / Gasification)
1. Partial Gasification or Pyrolysis /coking /carbonization / destructive distillation(heating in the absence of air)• Solid
• Liquid
• Gas
2. Complete gasification with air/oxygen• Gas
PYROLYSIS
Coke (solid fuel) maximum; classical domestic smokeless fuel production
Liquid fraction for chemicals recovery/liquid fuel
Coke for metallurgical furnaces; gas yield high; liquid low
Low temperature carbonization 500-700 oC
High temperature carbonization >900 oC
Medium temperature carbonization 700-900 oC
PYROLYSIS
Pyrolyser
Coal
Water in
Water out
Condenser
Gasfor IC engines/Gas turbines/thermal applications
Coke
Gas for heating of pyrolyser
Flue gas
Pretreatment unit
Liquid fraction
Coal tarLiquid fuelsChemicals
GASIFICATION
33
12x3=36 kg1k mole=1000.R.T/P (m3)=22.41 Nm3
≈18 Liter
(Air Separation Unit)
ROUTE IV BERGIUS PROCESS
1. Bergius processFriedrich Karl Rudolf Bergius (Germany) in 1913, Nobel Prize in 1931 (Shared with Carl Bosch)By end of World war II – most of the fuel for
German army was produced by this method.Hydrogenation of vegetable oils
2. Fischer-Tropsch processFranz Fischer and Hans Tropsch in 1926, Germany
Coal is hydrogen starved/hydrogen needs to be added to make it liquid (directly or indirectly)
BERGIUS PROCESS
Pulverizer
Coal pasting unit
HydrogenCoal
Fractionating column
BergiusReactor
Heavy fraction
HCs
T=400-500 oCP= 20 -70 MPa Catalyst=TinConver.=97%
F-T PROCESS
Gasification unit
Syn gasCleaning
Coal
Fractionating column
F-T Reactor
HCs
T=150-250 oCP= 1 -25 MpaCatalysts : Fe, Co
Syn gas
(Large number of patents worldwide)
F-T PROCESS (COMMERCIAL PLANTS) South Africa Oil and Gas
Company 1950 established Oldest plant proving the F-T
process viability Presently engaged in Qatar,
Iran and Nigeria in similarprojects
F-T PROCESS (COMMERCIAL PLANTS)
F-T PROCESS(COMMERCIAL PLANTS)
UNDERGROUND/ IN SITU COAL GASIFICATION
A process applied to the non-mined coal seams
Injection and production wells are drilled
End gas mix depends on type of coal seam
Air/ oxygen can be used for gasification
Syn gas can be used for power generation in combined cycle
Syn gas can be converted to chemicals/fuel by F-T process
UNDERGROUND/ IN SITU COAL GASIFICATION
Source: World Coal Institute
COAL COMBUSTION AND ENVIORNMENT Global warming Green house gases: water vapor, carbon dioxide,
methane, nitrous oxide, HFCs (hydrofluorocarbons), PFCs (perfluorocarbons), SF6 (Sulphur Hexafluoride)
SF6 is 22, 200 more potential than CO2 Carbon dioxide gas: main culprit from fossil fuels; not
from biomass Intergovernmental Panel on Climate Change (IPCC) Nobel Peace Prize 2007 : R. K. Pauchari and Al Gore Reduction in Carbon Dioxide emissions G8 meeting in Japan in July 2008
COAL COMBUSTION AND ENVIORNMENT
Carbon Dioxide Emissions and Carbon Dioxide Concentrations (1751-2004)
Present CO2 level:483 PPM
COAL COMBUSTION AND ENVIORNMENT
Global Carbon Cycle (Billion Metric Tons Carbon)
COAL COMBUSTION AND ENVIORNMENT
U.S. Anthropogenic Greenhouse Gas Emissions by Gas, 2006 (Million Metric Tons of Carbon Dioxide Equivalent)
ULTIMATE SOLUTIONS
Fuel cells: Chemical to electrical conversion
Solar: photovoltaic
Hybrid vehicles: Honda introduced in India