01 Coal - Its Origin Nature - Ranipet July 11 [Compatibility Mode]

Dr V T Sathyanathan

Mankind is in pursuit of truth, let us work towards this

Dr V T Sathyanathan


Coal Coal –– Its Origin & Its Origin &

NatureNatureDr V T SathyanathanRetired General Manager,

BHEL,Trichy 620014

Dr V T Sathyanathan


Dr V T SATHYANATHAN, Dr V T SATHYANATHAN, M.E., Ph.D.M.E., Ph.D.

� Graduated in Mechanical Engineering from Coimbatore Institute of Technology, Coimbatore in 1971.

� Master Degree In “Design And Production Of Thermal Power Equipment” From Regional Engineering College, Tiruchi in 1984.

� Ph.D Degree in Mechanical Engineering from Regional Engineering College, Tiruchi, in 1998 “Prediction of Unburnt Carbon in Tangentially Fired Boilers Using Indian Coals”.

� Joined BHEL In 1973, worked in R & D, Field Engineering Services, Engineering in various capacity & as General Manager/Quality for two years

� Retired as General Manger in 2008 from BHEL Trichy

� Presently Working As Technical Advisor in Cethar Vessels Limited Trichy

Dr V T Sathyanathan


Dr V T SATHYANATHAN, Dr V T SATHYANATHAN, M.E., Ph.D.M.E., Ph.D.

� Specialised

� In Coal, Oil & Gas Combustion, Boiler Pressure Parts Failure Analysis

� Trouble Shooting Of Coal , Oil And Gas Fired Boilers, Chemical

Recovery Boilers And Stoker Fired Boilers

� Plant Betterment Of Old Boilers

� Performance Testing & Performance Optimisation Of Boilers

� Has vast experience in the area of Residual Life Assessment of boiler

pressure parts

� Petrographic Analysis Of Coal

� Was appointed as the enquiry committee member by Government of

Tamilnadu, for investigation of a severe explosion in the Rotary Holding

Furnace (RHF) in Copper Smelting Plant of M/s. Sterlite Industries (I) Ltd.,

Tuticorin Tamilnadu

� Presented more than 40 papers in National and International Seminars.

� Write in www.brighthub.com – 83 Articles as on June 11

� My PhD work was referred by seven renowned universities abroad

� Teach Special Subjects In Horticulture - Art Of Bonsai & Cacti

Dr V T Sathyanathan


�Coal - General

�Coal Formation Theories

�Indian Coal Formation, Properties

& Behaviour

ArrangementArrangement

Dr V T Sathyanathan


Coal GeneralCoal General

Dr V T Sathyanathan


Dr V T Sathyanathan


Drifting of Continents

Dr V T Sathyanathan


Dr V T Sathyanathan


Large Swamps

Dr V T Sathyanathan


�In-situ coal formation

�Drift theory of coal formation

Coal formation theoriesCoal formation theories

Dr V T Sathyanathan


Coal formation theoriesCoal formation theories

Dr V T Sathyanathan


InIn--situ Theory of coal Formationsitu Theory of coal Formation

�Coal formed from a particular place

�Coal generally appear to have beenformed either in brackish or fresh water,from massive plant life growing inswamps, or in swamp interspersed withshallow lakes.

�Coal formed in this way have bands of coal and inorganic sedimentary rocks arranged in a sequence.

Dr V T Sathyanathan


Huge Tropical Ferns and Giant Trees in Huge Tropical Ferns and Giant Trees in

Vast Swamp AreasVast Swamp Areas ( ( WilfridWilfrid Francis, 1961 )Francis, 1961 )

Dr V T Sathyanathan


Drift Theory of Coal formationDrift Theory of Coal formation•Coal is formed largely from terrestrial plant materialgrowing on dry land and not in swamps or bogs.

•The original plant debris was transported by water anddeposited under water in lakes or in the sea. There willnot be a true soil found below the seam of coal.

•The transported plant debris, by its relative low densityeven when water logged, was sorted from inorganicsediment and drifted to a greater distance in open water.The sediments, inorganic and organic, settled down inregular succession according to their densities and tothe diminishing velocities of the carrying currents.

•The process of sedimentation of the organic andinorganic materials continue till the currents can depositthe transported vegetation in the locations.

•These deposits are covered subsequently by mineralmatters, sand etc. and result in coal seams.

Dr V T Sathyanathan


Drift Theory of Coal formation Drift Theory of Coal formation (Cont)(Cont)

• The depositions can also stop for a particular period

and again begin to happen depending upon the tidal

and current conditions.

• The coal properties vary widely due to the variedtype of vegetations deposited. Even animal remains,

algae plants and marine plants can be found to be

deposited. This is not possible in the case of theinsitu coal formation.

• It was the difference in coal properties of Gondwana

coals that led to the formation of the drift theory.

Dr V T Sathyanathan


GondwanaGondwana land land ( Stacks E., et al )( Stacks E., et al )

Dr V T Sathyanathan


Factors that Determine Factors that Determine Composition of CoalComposition of Coal

( ( WilfridWilfrid Francis, 1961 )Francis, 1961 )

�Mode of accumulation and burial of theplant debris forming the deposits.

�Age of the deposits and thegeographical distribution.

�Structure of the coal forming plants,particularly details of structure thataffect chemical composition orresistance to decay.

Dr V T Sathyanathan


Factors that Determine Factors that Determine Composition of Coal Composition of Coal (Cont)(Cont)

((WilfridWilfrid Francis, 1961)Francis, 1961)

�Chemical composition of the coal

forming debris and its resistance to

decay.

�Nature and intensity of the peat

decaying agencies.

�Subsequent geological history of the

residual products of decay of the

plant debris forming the deposits.

Dr V T Sathyanathan


Indian Coal Formation, Indian Coal Formation,

Properties & Properties & BehaviourBehaviour

Dr V T Sathyanathan


Indian Coal FormationIndian Coal Formation

� The Gondwana coals of peninsular India weregenerally believed to be drift origin. The mainreason for favouring such views include:

• pronounced regional variation in thicknessand quality of seams.

• high ash content of most of the seams.

• lateral transition of coal to carbonaceousshale

• absence of seat-earth and upright stems inthe under clays.

• scarcity of plant leaf impressions in the roofof coal seams and

• bifurcation and branching of coal seams.

Dr V T Sathyanathan


Dr V T Sathyanathan


MaceralsMacerals in Indian Coalin Indian Coal

A : Vitrinte B : Heat Affected Vitrinite C :Oxidised Vitrinite

D : Semi-Fusinite E : Composite Maceral Rich in Fusinite

Dr V T Sathyanathan


OxidisedOxidised and Weathered and Weathered

Coal Coal MaceralsMacerals

Dr V T Sathyanathan


Oxidation in Coal Results Oxidation in Coal Results ( Gray R. J., et al., 1974 ).( Gray R. J., et al., 1974 ).

�Poor coke

�Poor combustion

�Poor liquid conversion

�Reduced volatile matter

�Increased fines and dust problems

�Decreased free swelling index

Dr V T Sathyanathan


Carbonaceous Shale in Indian CoalCarbonaceous Shale in Indian Coal

Dr V T Sathyanathan


Coal Petrography & CombustionCoal Petrography & Combustion

� Petrographic analysis of coal was used to evaluate the pulverized coal combustion right from 1968

� The petrographic composition affects the ignition process, combustion and the efficiency of combustion. (Yavorskii I.A 1968)

� Combustion efficiency of the coal being burnt is inversely related to the inert maceral content of the coal i.e. semi-fusinite, fusinite and oxidised vitrinite

� Indian coals are found to have oxidised macerals in many cases which effects combustion

� Composite macerals are also often found in Indian coals which results in higher carbon loss

Dr V T Sathyanathan


Ash Properties & Ash Properties &

BehaviourBehaviour

Dr V T Sathyanathan


Inorganic Compounds Inorganic Compounds ––Four GroupsFour Groups

� Inorganic matter from original plants

� Inorganic - organic complex minerals formeddue to inorganic and organic interactionduring the first stage of coalificationprocess.

�Minerals introduced by water or wind into thecoal deposits as they were forming.

�Minerals deposited, during the second phaseof coalification process

Dr V T Sathyanathan


Ash Properties & BehaviourAsh Properties & Behaviour

� Combustion & ash deposition in a boiler is ancomplex process

� Coal devolatilisation

� Char combustion

� Mineral matter transformation

� Fly ash formation, transport & deposition

� Each of the above is influenced by

� Heating rate

� Temperature regime

� Localised gaseous environment

� Bulk & local fluid dynamic condition

Dr V T Sathyanathan


Ash Properties & Behaviour Ash Properties & Behaviour (cont.)(cont.)

� Slagging & fouling propensity of coals

� The viscosity of laboratory ash

� Ash fusion temperature

� Various laboratory ash composition ratios

• Iron : calcium

• Silica : alumina

• Base : acid

� Sodium-in-ash content

� Total alkali metal content in laboratory ash

� Segregation of ash during pulversing & its

properties

Dr V T Sathyanathan



In a Study Supported by EPRI

� Unusually complete sampling and analysis of coal,deposits and fly ash along with detailed operatingrecords led to the following conclusions:� Analysis of ash by coal density fractions showed distinct

differences between high slagging and low slagging coals

� Coal preparation to lower ash content also would decreasethe slagging potential

� High specific gravity fraction in slagging coals had calciumcontent expected to form low viscosity drop-lets downstreamof the flame

� Glassy spheres of melted ash making up furnace depositcame from individual particles of pulverised coal

� Unidentified mineral fractions which melted between 850 degC and 1100 deg C

� Spherical particles in contact with wall tube in furnacedeposits high in SiO2 & Al2O3.

Dr V T Sathyanathan



�Operational experience on slaggingfouling and corrosion in large dry bottomboilers have proven that the tendencytowards a conservative’ design is the rightway to minimise problems and damages.

But

� It has to be stated that because ofinsufficient knowledge of the coalconstituents - macerals & minerals - it isnot yet possible to propose an optimaldesign.

Dr V T Sathyanathan


INDIAN COALS INDIAN COALS

Vs Vs

OTHER COALSOTHER COALS

Dr V T Sathyanathan


Deterioration of Coal Quality Available for Power

Generation Over the Period

1970’s 1980’s 1990’s 2000’s

PROXIMATE ANALYSIS

FIXED CARBON % 36.5 32.4 25.0

VOLATILE MATTER % 25.5 21.6 18.0

MOISTURE % 10.0 16.0 12.0

ASH % 28.0 30.0 45.0

HHV kcal/kg 4750 4050 3000 2800

HGI 50 50 50 50

Dr V T Sathyanathan


Indian Coal Vs USA Coal

PARAMETER INDIAN UNIT USA UNIT

210 MW 500 MW 210 MW 500MW

HEAT DUTY mcal/h. 454 1070 454 1070

FUEL FIRED mkcal/h. 520 1215 520 1215

HHV kcal/kg. 3800 3800 6000 6000

QUANTITY OF FUEL t/h. 137 320 87 202.5

AVERAGE ASH CONTENT % 40 40 8 8

QUANITY OF ASH t/h. 55 128 7 16.2

Dr V T Sathyanathan


Amount of Coal / Ash Handled Over the Period

HHV kcal/kg 4750 4050 3000

Unit rating mw 210 500 210 500 210 500

ASH % 28 28 30 30 45 45

Fuel fired t/h 110 272 129 319 174 430

Ash produced t/h 30.8 76.2 38.7 95.7 78.3 193.5

Dr V T Sathyanathan


01 Coal - Its Origin Nature - Ranipet July 11 [Compatibility Mode]

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