for THERMAL POWER PLANTS
By
JVD RAO BE,MBAADE / Coal Coordinator/E&P
Dr.NTTPSAPGENCO
Mobile :9493120449
Contents
Coal Facts
1. Formation, Mining & Uses .....
2. Classification …..
3. Calorific Values of Fuels …..
4. Classification …..
5. Influence of coal nature …..
6. Fuels Grades & GCV’s …..
7. Analysis …..
Coal Handling at Dr. NTTPS
1. Introduction …..
2. Coal Preparation …..
3. Coal Linkages. …..
4. Typical Coal analysis Results …
5. Bunker Levels …..
6. Boiler Design Values …..
7. Delegation of powers –APGENCO …
8. Penalty calculations …..
9. Environmental standards ….
10. Free loading/unload timings …..
11. Demurrage charges …..
12. Delegation of powers-Railways ……
2
Appendix
1. Performance Calculations …..
2. Boiler Efficiency Calculations. …..
3. Air pre-heater performance ….
4. Conversions. …..
Annexure-Dr.NTTPS
1. CHP schematic diagram
2. Belt conveyors specifications
3. Wagon tipplers specifications
4. Crushers specifications
5. Stacker/Reclaimers specifications
3
PREFACE The coal hand book covers up with coal related topics such as Coal
formation, types, grades and prices, which also provides various coal
analyses with typical test results. It is more important to provide imported
coal information with typical test results.
This book may provide important and valuable information related to
coal handling plants of thermal plants (especially Dr.NTTPS) such as coal
linkages, grades, prices. It also provides major equipment details such as
wagon tipplers, belt conveyors, crushers and stacker/reclaimers.
In the last two and half years of my service in coal plant, DR.NTTPS as
ADE/COAL COORDINATOR, I have gone through major portion of the CHP
system and I also visited various sea ports to inspect and study the type of
coal received for APGENCO. As I had interest to get the knowledge on coal
handling system, I concentrated and studied more on coal and coal
handling system by regular observation and involvement and I also gone
through the system during interruptions and breakdown time gaps.
Finally my opt to think to inscribe this coal hand book is to provide
information regarding coal and CHP system of DR.NTTPS to the people
whoever eagerly searching for information on COAL and CHP System.
I have had considerable help and advice from many engineers, friends
and colleagues during the preparation of the various editions of this book. So,
I must thank to all for their valuable suggestions and guidance, especially
thanks to Er.G.Sampath Kumar, DE/E&P-IV/DR.NTTPS for his valuable support
and involvement during the editing and designing of this valuable edition.
-JVDRAO
4
COAL FACTS
Coal Formation:
Fossil fuels are derived from plant and animal matter. They formed
naturally over millions of years. These energy-producing fuels are the remains
of ancient life that have undergone changes due to heat and pressure. The
primary fossil fuels are coal, petroleum and natural gas. Together they
account for 85% of the world's energy consumption.
Coal is a dark, combustible material formed, through a process known
as coalification, from plants growing primarily in swamp regions. Layers of
fallen plant material accumulated and partially decayed in these wet
environments to form a spongy, coarse substance called peat. Over time, this
material was compressed under sand and mud, and heated by the earth to
be transformed into coal. Some scientists refer to coal as sedimentary rock.
Coal is primarily composed of carbon, hydrogen, oxygen and nitrogen.
There are several classifications of coal, which are rated according to
their carbon content and heating value. The heating value of coal is
expressed in Kcal/Kg.
Coal Mining
The two main types of coal mining are
1. Surface (strip) mining and 2.underground mining.
Strip mining
It involves the removal of coal deposits close to earth's surface (usually
no more than 100 feet from the surface). Topsoil and rocks are removed from
the surface to expose the coal deposits. Explosives and heavy machinery are
used to break up and remove layers of coal.
Underground mining
It involves the removal of coal deposits, often hundreds of feet below
the earth's surface. (Some mines may be close to 2,000 feet deep.) Shafts or
tunnels are dug into the coal layers and widened to allow room for the miners
and coal cars or conveyor belts. Additional shafts may be excavated to
increase air ventilation for the miners.
5
Coal Uses
Coal is used to generate heat, produce electricity, and make steel and
industrial products. It is used worldwide as a fuel, second only to petroleum as
the most consumed energy resource.
Coal Classification
As geological processes apply pressure to dead biotic material over
time, under suitable conditions it is transformed successively into
Peat: It is considered to be a precursor of coal, has industrial importance as a
fuel in some regions, for example, Ireland and Finland. In its dehydrated form,
peat is a highly effective absorbent for fuel and oil spills on land and water.
Lignite: It is also referred to as brown coal, is the lowest rank of coal and used
almost exclusively as fuel for electric power generation. Jet is a compact
form of lignite that is sometimes polished and has been used as an
ornamental stone since the Upper Paleolithic.
Sub-bituminous coal : This coal properties range from those of lignite to those
of bituminous coal is used primarily as fuel for steam-electric power
generation. Additionally, it is an important source of light aromatic
hydrocarbons for the chemical synthesis industry.
Bituminous coal : it’s look like a dense sedimentary rock, black but sometimes
dark brown, often with well-defined bands of bright and dull material, used
primarily as fuel in steam-electric power generation, with substantial
quantities also used for heat and power applications in manufacturing and to
make coke.
Steam coal: It is a coal having grade between bituminous coal and
anthracite, once widely used as a fuel for steam locomotives. In this
specialized use it is sometimes known as sea-coal in the U.S.
Anthracite : it is the highest rank; a harder, glossy, black coal used primarily
for residential and commercial space heating.
6
Graphite : It is technically the highest rank, but difficult to ignite and is not so
commonly used as fuel: it is mostly used in pencils and, when a powdered, as
a lubricant.
CALORIFIC VALUE OF FUELS
Calorific value (CV)The calorific value is defined as the quantity of heat liberated on the
complete combustion of a unit weight or unit volume of fuel, at constant pressure and under the conditions known as “normal” of temperature and pressure (i.e. to 0°C and under a pressure of 1 .013 mbar). It is measured in units of energy per unit of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m³.
Gross Calorific Value (GCV)The higher calorific value (or) Gross calorific value (GCV) which
supposes that the water of combustion is entirely condensed. The heat contained in this water is recovered.
Net Calorific Value (NCV): The lower calorific value (or) Net calorific value (NCV) which supposes that the products of combustion contain the water of combustion in the vapor state. The heat contained in this water is not recovered.
Heat Rate (HR):
The amount of heat input required per unit of power generated (kcal/kwh) for specific fuel being fired and specific site conditions. A measure of generating station thermal efficiency, generally expressed in btu per net kwh. It is computed by dividing the total btu content of fuel burned for electric generation by the resulting net kwh generation.
Dulong’s formulae for GCV calculation :
According to Dulong's formula
GCV = ((35.5 x C + 114.8 x H + 9.5 x S – 14.5 x O) x 1000) (100 x 4.1868)
7
Measurement of GCV in different basis
The variables are measured in weight percent (wt. %) and are calculated in several basis, they are
AR (as-received) basis is the most widely used basis in industrial
applications. AR basis puts all variables into consideration and uses the
total weight as the basis of measurement.
AS RECEIVED BASIS (AR) = TM+IM+ASH+VM+FC+S (Includes all moistures)
AD (air-dried) basis is to neglect the presence of moistures other than
inherent moisture while DB (dry-basis) leaves out all moistures, including
surface moisture, inherent moisture, and other moistures.
AS DRIED BASIS (AD) = 0+IM+ASH+VM+FC+S (Includes Inherent moisture)
DAF (dry, ash free) basis is to neglect all moisture and ash constituent in
coal
AS DRY ASH FREE (DAF) = 0+0+0+VM+FC+0 (Excludes all moisture & Ash)
DMMF (dry, mineral-matter-free) basis leaves out the presence of
moisture and mineral matters in coal, for example: quartz, pyrite,
calcite, etc. Mineral matter is not directly measured but may be
obtained by one of a number of empirical formula based on the
ultimate and proximate analysis.
AS DRY BASIS (DB) = 0+0+ASH+VM+FC+S (Excludes all moisture)
(TM=Total Moisture, IM=Inherent Moisture, VM=Volatile Matter, FM=Fixed Carbon, S=Sulphur)
8
Influence of Coal Properties
Properties effect on Specific Coal Consumption
The effect of various coal properties like ash content, moisture content,
fixed carbon and calorific value on specific coal consumption in a typical
thermal power station in India is analyzed. It is observed that the specific coal
consumption is a strong function of moisture content, ash content and fixed
carbon. For the known Thermal Power Station (as considered in the present
analysis), it is observed that, for an increase in moisture content by 2%, the
specific coal consumption increases by about 8%. If, however, the ash
content is increased by 2%, the specific coal consumption increases by about
5%. It is also observed that, for a 4% increase in fixed carbon, the specific coal
consumption decreases by about 25%.
Coal Boulders on performance
Delay in unloading, which also pay demurrage charges to railways.
More labor required to clear off boulders. Damage of conveyers and equipments. Damage of crushers Jamming of chutes and hoppers. No coal flows at bowl mills. Loss of generation. Wastage men & machine running hours.
Coal Wetness on performance
Delay in unloading, which also pay demurrages to railways. More labor required to clear off wet coal. Damage of conveyers and equipments. Jamming of chutes, hoppers and crushers. Due to wetness loss of generation. No coal flows at bowl mills. Formation of clinkers in boilers. System troubles.
9
FUELS GRADE & GCV ‘S
I.COAL GRADES
The gradation of non-coking coal is based on Useful Heat Value (UHV), the gradation of coking coal is based on ash content and for semi coking / weakly coking coal it is based on ash plus moisture content , as in vogue as per notification. Grades of Coking Coal:
Grade Ash ContentSteel Grade –I Not exceeding 15%Steel Grade -II Exceeding 15% but not exceeding 18%Washery Grade -I Exceeding 18% but not exceeding 21%Washery Grade -II Exceeding 21% but not exceeding 24%Washery Grade -III Exceeding 24% but not exceeding 28%Washery Grade -IV Exceeding 28% but not exceeding 35%
Grades of Non-coking Coal:
Grade Useful Heat Value (UHV)(Kcal/Kg)
UHV= 8900-138(A+M)
CorrespondingAsh% + Moisture % at (60% RH & 40O C)
Gross Calorific Value(GCV) (Kcal/ Kg)
(at 5% moisture level)A Exceeding 6200 Not exceeding 19.5Exceeding 6454B Exceeding 5600 but not
exceeding 620019.6 to 23.8 Exceeding 6049
but not exceeding 6454C Exceeding 4940 but not
exceeding 560023.9 to 28.6 Exceeding 5597
but not exceeding. 6049D Exceeding 4200 but not
exceeding 494028.7 to 34.0 Exceeding 5089
but not Exceeding 5597E Exceeding 3360 but not
exceeding 420034.1 to 40.0 Exceeding 4324
But not exceeding 5089F Exceeding 2400 but not
exceeding 336040.1 to 47.0 Exceeding 3865
but not exceeding. 4324G Exceeding 1300 but not
exceeding 240047.1 to 55.0 Exceeding 3113
but not exceeding 3865
Grades of Semi-coking and Weakly Coking Coal:
Grade Ash + Moisture ContentSemi coking grade –I Not exceeding 19%Semi coking grade –II Exceeding 19% but not exceeding 24%
Grades of NEC Coal :
10
Grades UHV (Kcal/Kg) CorrespondingAsh% + Moisture %age
A 6200-6299 18.85 – 19.57B 5600 – 6199 19.58 – 23.91
II.BIO-MASS FUELS:
SNo Fuel Approx heating value Kcal/Kg Natural State
Drystate
1 Wood 1500 3500 2 Cattle dung 1000 3700 3 Bagasse 2200 4400 4 Wheat and rice straw 2400 2500 5 Cane trash, rice husk, leaves and
vegetable wastes 3000 3000
6 Coconut husks, dry grass and crop residues
3500 3500
7 Groundnut shells 4000 4000 8 Coffee and oil palm husks 4200 4200 9 Cotton husks 4400 4400 10 Peat 6500 6500
III.FOSSIL FUELS:
1 Coal 4000-7000 2 Coke 6500 3 Charcoal 7000 4 Carbon 8000 5 Fuel oil 9800 6 Kerosene and diesel 10000 7 Petrol 10800 8 Paraffin 10500 9 Natural gas 8600 10 Coal gas 4000 11 Electrical (Kcal(KW) 860 12 Bio gas(Kcal/cu mtr) (12 kg of dung
produces 1 cu. Mtr gas) 4700-6000
11
IV.OILS
LDO (As Per IS 1460-1974) : It is generally used for start up of boiler.
Description Values
Relative Density @15oC/15oC 0.85Flash Point PMCC oC min 38oCKinematic Viscosity CST 2 to 7.5Sulphur %by weight max 1%Ash weight max 0.02Gross calorific value Kcal/Kg(Average)
10720
LSHS/HFO (As Per IS 1593-1971) : It is generally used for Warm up & flame stabilization of boiler. Description ValuesRelative Density @15oC/15oC 0.9579Flash Point PMCC oC min 66oC (min)
120oC (min)Kinematic Viscosity CST 500 CST maxPour Point oC max 72oC Sulphur %by weight max 4.5%Sediment % by weight Max 4.5% Ash weight max 0.1Water content % Vol .Max 1.0Gross calorific value Kcal/Kg(Average)
10000
12
Analysis of Coal
There are two methods 1. Proximate analysis and 2. Ultimate analysis.
Proximate Analysis
The objective of proximate analysis indicates the percentage by
weight of the Fixed Carbon, Volatiles, Ash, and Moisture Content in coal. The
amounts of fixed carbon and volatile combustible matter directly contribute
to the heating value of coal. Fixed carbon acts as a main heat generator
during burning. High volatile matter content indicates easy ignition of fuel. The
ash content is important in the design of the furnace grate, combustion
volume, pollution control equipment and ash handling systems of a furnace.
The definition, importance and measure of coal parameters are
explained as follows
Moisture Moisture is an important property of coal, as all coals are mined
wet. Groundwater and other extraneous moisture is known as adventitious moisture and is readily evaporated. Moisture held within the coal itself is known as inherent moisture.
Typical range of Moisture content is 0.5 to 10%.
Moisture may occur in four forms within coal: Surface moisture:
Water held on the surface of coal particles or minerals. Hydroscopic moisture:
Water held by capillary action within the micro fractures of the coal
Decomposition moisture: Water held within the coal’s decomposed organic
compounds Mineral moisture:
Water which comprises part of the crystal structure of hydrous silicates such as clays.
Measurement: Determination of moisture is carried out by placing a
sample of powdered raw coal of size 200-micron size in an uncovered
crucible and it is placed in the oven kept at 108+2 C along with the lid.
Then the sample is cooled to room temperature and weighed again. The
loss in weight represents moisture.
13
Volatile Matter
Volatile matter in coal refers to the components of coal, except
for moisture, which are liberated at high temperature in the absence of
air. This is usually a mixture of short and long chain hydrocarbons,
aromatic hydrocarbons and some sulfur.
Typical range of volatile matter is 20 to 35%.
Measurement: Fresh sample of crushed coal is weighed, placed in a
covered crucible, and heated in a furnace at 900 + 15ºC. For the
methodologies including that for carbon and ash, refer to IS 1350 part
I:1984, part III, IV. The sample is cooled and weighed. Loss of weight
represents moisture and volatile matter. The remainder is coke (fixed
carbon and ash).
Ash and Fixed Carbon
The Ash content of coal is the non-combustible residue left after
coal is burnt. It represents the bulk mineral matter after carbon, oxygen,
sulfur and water (including from clays) has been driven off during
combustion. Analysis is fairly straightforward, with the coal thoroughly
burnt and the ash material expressed as a percentage of the original
weight. Typical range Ash content is 5 to 40%.
The fixed carbon content of the coal is the carbon found in the
material which is left after volatile materials are driven off. This differs
from the ultimate carbon content of the coal because some carbon is
lost in hydrocarbons with the volatiles. Fixed carbon is used as an
estimate of the amount of coke that will be yielded from a sample of
coal. It gives a rough estimate of heating value of coal.
Measurement: The cover from the crucible used in the last test is
removed and the crucible is heated over the Bunsen burner until all the
carbon is burned. The residue is weighed, which is the incombustible
ash. The difference in weight from the previous weighing is the fixed
carbon. (In actual practice Fixed Carbon or FC derived by subtracting
from 100 the value of moisture, volatile matter and ash).
14
TYPICAL RESULTS:
PARAMETRS INDIAN (F) INDONESIAN SOUTH AFRICAMOISTURE 5.98% 9.43% 8.50%ASH 38.63% 13.99% 17.00%VOLATILE MATTER 20.70% 29.79% 23.28%FIXED CARBON 34.69% 46.79% 51.22%
Ultimate Analysis
The objective of ultimate analysis is to determine the amount of
carbon (C), hydrogen (H), oxygen (O), sulfur (S), and other elements within
the coal sample. The determination of the carbon and hydrogen in the
material, as found in the gaseous products of its complete combustion, the
determination of sulfur, nitrogen, and ash in the material as a whole, and the
estimation of oxygen by difference. The carbon determination includes that
present in the organic coal substance and any originally present as mineral
carbonate. The hydrogen determination includes that in the organic
materials in coal and in all water associated with the coal. All nitrogen
determined is assumed to be part of the organic materials in coal.
For practical reasons, sulfur is assumed to occur in three forms in coal:
as organic sulfur compounds, as inorganic sulfides, which are mostly the iron
sulfides pyrite and marcasite, and as inorganic sulfates. The total sulfur value is
used for ultimate analysis.
TYPICAL RESULTS:
PARAMETRS INDIAN(F) INDONESIANMOISTURE 5.83% 9.43%MINERAL MATTER
38.63% 13.99%
CARBON 41.11% 58.96%HYDROGEN 2.76% 4.16%NITROGEN 1.22% 1.02%SULPHUR 0.41% 0.56%OXYGEN 9.89% 11.88%
15
COAL HANDLING AT Dr NTTPS
Introduction
The Dr.Narla tatarao Thermal power station is one of the biggest power
plant in India which is having an installed capacity of 1760 MW running under
the control of well known organization i.e., APGENCO. For running this power
plant coal is receiving from various places/mines such as Talcheru (Orissa),
Singareni Collieries (Andhra) and Indonesia. The details of mines and their
coal grades are here with furnished for information.
Storage and Handling of Coal
Uncertainty in the availability and transportation of fuel
necessitates storage and subsequent handling. The main aim of coal
storage is to minimize carpet loss and the loss due to spontaneous
combustion. Formation of a soft carpet, comprising of coal dust and
soil causes carpet loss. On the other hand, gradual temperature builds
up in a coal heap, on account of oxidation may lead to spontaneous
combustion of coal in storage.
Stocking of coal has its own disadvantages like build-up of
inventory, space constraints, deterioration in quality and potential fire
hazards. Other minor losses associated with the storage of coal include
oxidation, wind and carpet loss. A 1% oxidation of coal has the same
effect as 1% ash in coal, windage losses may account for nearly 0.5 –
1.0% of the total loss.
Methods to reduce carpet losses:
1. Preparing a hard ground for coal to be stacked upon.
2. Preparing standard storage bays out of concrete and brick
16
Preparation of Coal
Preparation of coal prior to feeding into the boiler is an important step
for achieving good combustion.
Large and irregular lumps of coal may cause the following problems:
1. Poor combustion conditions and inadequate furnace temperature.
2. Higher excess air resulting in higher stack loss.
3. Increase of unburnts in the ash.
4. Low thermal efficiency.
Therefore, it is compulsion to make proper sizing of coal by different
ways
Sizing of Coal:
Proper coal sizing is one of the key measures to ensure efficient
combustion. Proper coal sizing, with specific relevance to the type of firing
system, helps towards even burning, reduced ash losses and better
combustion efficiency. Coal is reduced in size by crushing and pulverizing.
Pre-crushed coal can be economical for smaller units, especially those
which are stoker fired. In a coal handling system, crushing is limited to a
top size of 6 or 4mm. The devices most commonly used for crushing are
the rotary breaker, the roll crusher and the hammer mill. It is necessary to
screen the coal before crushing, so that only oversized coal is fed to the
crusher. This helps to reduce power consumption in the crusher.
Recommended practices in coal crushing are
1. Incorporation of a screen to separate fines and small particles to avoid
extra fine generation in crushing.
2. Incorporation of a magnetic separator to separate iron pieces in coal,
which may damage the crusher.
17
APGENCO COAL LINKAGES :
1. Mahanadhi Coal Fields, Talcher(Orissa) • Talcheru mines
2. Singareni Collieries Limited , Kothagudem (A.P)• Manugur• Manchiryala• badrachalam Road• Ramagunadam-I • Ramagunadam-II• Rudrampur.• Uppal.• Mandamarri • Kothagudem • Yellandu • Bhoopalapalli• Bellampalli• Srirampur • Apa
3. PEC LTD (Imported Coal)• Indonesia • South Africa
4. MSTC LTD (imported Coal) • Indonesia • South Africa
5. NCCF LTD (imported Coal)o Indonesia o South Africa
18
Mahanadhi Coal Fields Ltd,Talcher Talcher is the major coal loading point of the Division and commands
the status of being the ‘biggest coal loading point served from one station’ in
the whole of Asia. Talcher area consists of 9 coal loading sidings of M/s
Mahanadi Coal Fields Ltd., from where coal gets transported to the thermal
power plants of NTPC at Talcher and Kaniha, and other power houses of
South India via rail routes and the sea route through Paradip (via coastal
shipping). Talcher coalfield, located in the district of Angul of Orissa State, is
one of the major coalfields containing huge reserves of power grade non-
coking coal. The total area of the coalfield is 1860 sq.Kms. where as potential
area is 1580 sq.km.
The total geological reserve is 36868.12 million tonns, which constitutes
18.7% of the country’s total reserve.
Talcher -18 private sidings:
Three sidings (Talcher) Five sidings (Paradip)
Three sidings(Khurda Road)
Eight other private sidings (Gopalpur Port, Ganjam,Sukinda
Road,Ghantikal Nidhipur,Charbatia,Budhapank ,Byree,Meramandali)
19
Talcheru Coal mines:
At present there are 7 nos. of opencast mines and 3 nos. of
underground mines in operation with manpower of 10,220.
A. Open Cast Mines
Sl.No. Name of the Area Name of the Open Cast
01. Jagannath Balanda
02. Jagannath
03. Ananta
04. Kalinga Kalinga
05. Bharatpur
06 Hingula Hingula
07. Lingaraj Lingaraj
B. Under Ground Mines
Sl.No. Name of the Area Name of the Under Ground
01. Talcher Deulabeda
02. Talcher
03. Nandira
Talcher Coal mine Properties
MINE PLACE (GRADE) VOLATILE MATTER (%)
ASH (%) FIXED CARBON
(%)JAGANATH(F) 31.60 36.17 32.23ANANTHA(F) 25.26 43.16 31.58
BHARATHPUR(D) 34.67 21.74 43.59BELPAHAR(F) 25.98 39.13 34.89
DHERA(F) 24.69 52.04 23.27KALINGA(F) 21.88 46.35 31.77NANDIRA(F) 26.70 39.18 34.12
LINGARAJ (D) 39.20 15.93 44.95
20
SINGARENI COAL FIELDS Ltd, Kothagudem
The Singareni Collieries Company Limited (SCCL) is a Government coal
mining company jointly owned by the Government of Andhra Pradesh and
Government of India on a 51:49 equity basis. The Singareni coal reserves
stretch across 350 Km of the Pranahita – Godavari Valley of Andhra Pradesh
with a proven geological reserves aggregating to whopping 8791 million
tonnes. SCCL is currently operating 13 opencast and 42 underground mines in
4 districts of Andhra Pradesh with a man power around 78,000.
The recent studies of Geological Survey of India attribute as much as
22016 million tonnes of coal reserves in the Godavari valley coalfield. The
inventory covers up to a depth of 1200 meters and it includes reserves
proved, indicated as well as inferred. The coal extracted by SCCL in the
Godavari valley coalfield up to the year 2009-10 was about 929.12 million
tonnes.
SCCL Coal Definitions:
ROM COAL: Run of Mine coal is coal comprising of all sizes which come out of the mine without any crushing or screening.
Steam coal: The fraction of the Run of Mine coal as is retained on a screen when subjected to screening OR is picked out by fork shovel during loading is called Steam coal.
Slack coal : The fraction that remains after Steam Coal has been removed from the Run of Mine coal is called Slack coal.
CRUSHED ROM COAL: When the top size is limited to any maximum limit within the range of 200 – 250 mm through manual facilities or mechanical facilities is called Crushed ROM Coal.
21
Singareni Coal Grades and Prices :
The revised Grade- wise Basic prices of Run of Mine (ROM) coal of the
Singareni Collieries Company Limited as follows.(as on 01-04-2011)
Basic prices of Washery Grade coal :
Grade PriceWashery Grade - D Rs.2778Washery Grade - E Rs.1690Washery Grade - F Rs.1490
Typical coal results:
22
Grade of CoalUseful Heat Value per Kcal/Kg
ROM Coal(in Rs.)
‘A’ Exceeding 6200 3393
‘B’Exceeding 5600 but not exceeding 6200
2886
‘C’Exceeding 4940 but not exceeding 5600 1840
‘D’Exceeding 4200 but not exceeding 4940 1500
‘E’Exceeding 3360 but not exceeding 4200 1130
‘F’Exceeding 2400 but not exceeding 3360
690
‘G’Exceeding 1300 but not exceeding 2400
510
In Dr.NTTPS the coal will be received from different companies and mines that could be tested at coal lab for analysis of GCV and other parameters. The coal test results of two types of coals are provided here for reference.
1.INDIAN COAL:( “F “GRADE )
PARAMETERS VALUESUHV 2483Internal moisture 5.83%Total moisture 10.99%Ash 40.67%
2.IMPORTED COAL:
PARAMETERS VALUES GCV(ADB) 6207 Kcal/Kg
Internal moisture 6.82%Total moisture 11.63%
Ash(ADB) 9.18%Sulphur (ADB) 0.51%
Volatile matter 37.28%Size of coal <50 MM
23
DR.NTTPS BUNKER LEVELS BUNKER EMPTY IN MTRS (FROM TOP )
COAL AVAILABLE (MT) COAL TO BE FILLED (MT)STAGE I STAGE II & III STAGE IV STAGE I STAGE II & III STAGE IV
0 500 500 630 0 0 0
1 440 425 593 60 75 37
2 330 365 556 170 135 74
3 235 309 519 265 191 111
4 175 254 482 325 246 148
5 - 190 445 - 310 185
6 100 139 408 400 361 222
7 - 109 371 - 391 259
8 75 92 334 - 408 296
9 30 67 297 470 433 333
10 - 33 260 - 467 370
11 - 24 223 - 476 407
12 20 15 186 480 485 444
13 - 4.5 149 - 495.5 481
14 - 2.5 112 - 197.5 518
15 -- - 75 - - 555
16 - - 38 - - 592
17 - - 0 - - 630
24
Dr.NTTPS UNITS- BOILER DESIGN VALUES:
Note: It was studied that the coal consumption of units may be varying depends upon the type/grade of coal is fed to the bunkers.In practice it is not possible to feed exactly the designed GCV coal. Hence the coal consumption of units may be varied accordingly.
Delegation of powers:
a).Transit Losses –Powers of Waiver (as per delegations): Loss in Percentage Delegation of Powers UP TO 2% Chief Engineer/O&M 2 TO 3% Chief Engineer/GENERATION-II > 3% BOARD OF DIRECTORS
b).Windage & Shrinkage Losses–Powers of Waiver (as per delegations): Loss in Percentage Delegation of Powers UP TO 0.6% Chief Engineer/O&M 0.6 TO 1.2 % Chief Engineer/GENERATION-II > 1.2% BOARD OF DIRECTORS
(Note: As per APERC Norms Transit Loss is 0.8% (Max.))
UNIT#Capacity
(MW)GCV
(KCAL/KG)HEAT
RATE(KCAL/KWh)SPCC
(KG/KWHR)
COAL CONSUMPTION
(MT)
1 210 4500 2351 0.522 2631
2 210 4500 2351 0.522 2631
3 210 3686 2301 0.624 3145
4 210 3686 2301 0.624 3145
5 210 3686 2251 0.612 3078
6 210 3686 2251 0.612 3078
7 500 4400 2188 0.496 5952
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Coal Penalty Calculations (APGENCO)
a).On Excess Wetness:
If 1% excess moisture found in coal then the penalty is calculated as follows:
Formulae=Rake wt * Extra Moisture% * 2 * Cost/MT Eg: Rake wt: 3600 MT Extra Moisture: 1% Cost /MT: Rs.5555 (AS PER PO price/MT) Penalty =3600 *0.01*2*5555 = Rs.3,99,960/Rake.
b).On Excess Ash :
If 1% excess ASH found in coal then the penalty is calculated as follows:
Formulae=Rake wt * Extra Ash% * 1 * Cost/MT
Eg: Rake wt: 3600 MT Extra Ash: 1% Cost /MT: Rs.5555 (AS PER PO PRICE/Mt) Penalty =3600 *0.01*1*5555 = Rs.1, 99,980/Rake.
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ENVIRONMENTAL STANDARDS –Thermal Power Plants:
The emission standards for thermal power plants in India are being enforced based on Environment (Protection) Act, 1986 of Government of India and it’s amendments from time to time. A summary of emission norms for coal based thermal power plants is given in Tables
Emission Standards:
Stack
Height/Limits: (Stack height requirement for SO2 control)
Capacity Stack Height (Meter)
Less than 200/210 MWeH = 14 (Q)0.3 where Q is emission rate of SO 2 in kg/hr, H = Stack height in meters
200/210 MWe (or)less than 500 MWe
200
500 MWe and Above275
(+ Space provision for FGD systems in future)
The norm for 500 MW and above coal based power plant being practiced
is 40 to 50 mg/Nm and space is provided in the plant layout for super thermal
power stations for installation of flue gas desulphurisation (FGD) system. But FGD is
not installed, as it is not required for low sulphur Indian coals while considering SO
X emission from individual chimney.
Capacity Pollutant Emission limit
Below 210 MWParticulate matter(PM) 350 mg/Nm3
210 MW & aboveParticulate matter(PM) 150 mg/Nm3
500 MW & aboveParticulate matter(PM) 50 mg/Nm3
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FREE TIME FOR LOADING/UNLOADING OF WAGONS AT GOODS SHEDS & SIDINGS: (As per Indian railways)
Type of wagons Loading (Hrs:Mts)
Unloading (Hrs:Mts)
OPEN WAGONSlike BOXN, BOX, BOY, BOI,BOST, BOXNHA, BOXNHS,NBOY etc
5:00 7:00
HOPPER WAGONSlike BOBS, NBOBS, BOBR,NBOBR, BOBY, NBOBY etc.
5:00
2:30FLAT WAGONSlike BFR, BRH, BRN, BFK,BFKI, BFNS, CONCORDrakes etc.
6:00 N.A
TANK WAGONS(black oil)
7:00
7:00 (up to 29 wagons) 9:00(30 wagons & above)
RATES OF DEMMURRAGE CHARGES :(As per Indian railways)
Rates of demurrage charges per 8-wheeled wagon per hour or part of an
hour for detention of wagon in excess of the permissible free time notified for the
wagon for loading or unloading shall be as under.
Detention in excess of
permissible free time
Broad
Gauge
Meter
Gauge
Narrow
GaugeFirst 24 hrs Rs.100/- Rs.70/- Rs.50/-Next 24 Hrs Rs.200/- Rs.140/- Rs.100/-Beyond 48 hrs Rs.300/- Rs.210/- Rs.150/-
Delegation of Powers to waive Demurrage Charges:
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S.No.Designation of
officer at corporateand Regional level
Maximum amount ofdemurrage per wagon
which can be consideredby an officer
1 MD Full Powers2 Director (O&C) Rs.2,00,000/-3 CCM Rs.1,00,000/-4 RRM Rs.25,000/-5 Sr.RTM Rs.6,000/-6 STM Rs.600/-
7ACM/ATM/Area
Officer in Jr.ScaleRs.300/-
APPENDIX
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Performance Calculations -Thermal Plants
1. Plant Load Factor (PLF) = Generation Achieved In Month x 100 Possible Generation in Month
2. Availability factor (AF) = Actual running hours x 100 Possible running hours
3. Loading factor = PLF Availability
4. Specific Coal Consumption = Coal consumption (fed to bunkers as per coal plant) Generation
5. Specific Oil = Oil Consumption Consumption Generation 6. Deemed Generation = Generation + Back down 7. Deemed PLF = Generation + Back down Possible Generation8. Heat rate = (Weighted average CV of coal*Coal consumption+ Weighted average CV of oil*Oil consumption) Generation x 1000
BOILER Efficiency Calculations
1. Ash collected /Kg. of fuel in Fly Ash = % Ash in Coal X % Ash appearing at ESP
100- % Combustibles in Fly Ash
2. Ash collected / Kg. of fuel in Bottom Ash = % Ash in Coal X % Ash appearing in furnace bottom
100 - % Combustibles in Bottom Ash
3. Combustibles in Fly Ash / Kg. = Ash collected per Kg. of fuel in Fly Ash X % Combustibles in Fly Ash100
4. Combustibles in Bottom Ash/ Kg. = Ash collected /Kg. of fuel in Bottom Ash X % Combustibles in Bottom Ash
100
5. % Total Combustibles in Fly Ash and Bottom Ash per Kg. of fuel fired = (Combustibles in Fly Ash per Kg. + Combustibles in Bottom Ash per
Kg.)X100
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6. Dry Gas Quantity after APH = __________1______________( % C + % S - % M ) 12 X % CO2 in FG after AH 2.67
7. Sensible Heat in FG leaving APH = Dry Gas Quantity X Specific Heat ( tg - ta
)
8. % Dry Gas Loss = Sensible Heat in Flue Gas X 1004.186X CV of Coal
9. % Loss due to Combustibles in Ash = Total Combustibles in Ash X CV of Carbon X 100
CV of Coal10. Total Moisture = % Moisture in Coal + ( 9 X % Hydrogen in Coal )
10011. Heat loss per Kg. of Moisture = Specific Heat of Moisture ( FG Temp. at AH O/L - Min. Gas Temp) + Enthalpy of vapor in the process of Combustion(Latent Heat of water) + 4.2 ( MGT - Dry Bulb Temp)
12. % Loss due to Moisture &Hydrogen in Fuel = Total Moisture X Heat/Kg. of Moisture X100 4.186 X CV of Coal
13. % Loss due to Fly Ash = 0.9 X Ash in Coal X ( FG Temp. at AH O/L - Dry bulb temp.)CV of Coal
14. % Loss due to Bottom Ash =0.1 X Ash in Coal X Specific Heat of Ash ( Bottom ash Temp. - Dry Bulb Temp.)
CV of Coal
15. Total % Loss due to Sensible Heat in Ash = % Loss due to Fly Ash + % Loss due to Bottom Ash
16. O2 required for % Carbon in Coal Kg. = O2 required per Kg. of Carbon X % Carbon in Coal 100
17. O2 required for % Sulphur in Coal Kg. = O2 required per Kg. of Sulphur X % Sulphur in Coal
100 10018. Total O2 required = O2 required for (Carbon + Hydrogen + Sulphur) - O2 in Coal
19. O2 required for % Hydrogen in Coal Kg. = O2 required per Kg. of Hydrogen X % Hydrogen in Coal
100 100
20. Stiochiometric Dry Air = Total O2 required X 100 % O2 in Atmosphere by weight
21. % Excess Air = 21 . 21- % O2 from Orsat Analysis after AH
22. Total Combustion Air = % Excess Air X Stoichiometric Dry Air 23. % Loss due to Air Moisture = Moisture in Air X Total Combustion Air X 1.88 (tg – ta ) X 100
4.186 X CV of Coal
24. % Total Loss = % Loss due to (Dry gas+Combustibles+Moisture & Hydrogen in fuel+Sensible Heat+Radiation+Air Moisture)
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25. Boiler efficiency = 100 - % Total Loss
Performance Calculations -AIR PREHEATER
1. Temperature Head = (FG Temp before AH) – (Sec' Air Temp before AH)
2. % Leakage of CO2 = (% CO2 in FG before AH - % CO2 in FG after AH) x 90 % CO2 in FG after AH
3. Corrected exit gas temperature without leakage =(% Leakage of CO2 / 100) x 0.95 ( FG Temp after AH - Sec' Air Temp before AH) + FG Temp after AH
4. Corrected gas temp drop without leakage= (FG Temp before AH - Corrected exit
gas temp Without leakage)
5. Temperature without leakage =(% Leakage of CO2 / 100) x 0.95 ( FG Temp after AH - Sec' Air Temp before AH) + FG Temp after AH
6. Gas side Efficiency = (Corrected gas temperature drop x 100 ) Temperature Head
7. % Excess Air before APH =[21/(21- % O2 before AH)]-1
8. % Excess Air after APH = [21/(21- % O2 after AH)]-2
9. Stoichimetric Air (Actual air required for Combustion) = Total Air Flow (1+ % Excess air before AH)
10. Air Flow at AH Outlet = Stoichimetric Air (1+ % Excess air after AH)
11. Leakage across APH= Air flow at AH Outlet - Total Air Flow
12. % Leakage across APH = Leakage across AH Total Air Flow
CONVERSIONS
ENERGY CONVERSIONS:
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British
Thermal Unit
Foot-pounds
Joules calories Kcal Kwhr
1 British Thermal Unit
1 777.9 1055 252.0 0.252 2.93x10-4
1 Foot-pound
0.001285 1 1.356 0.3238 3.238x10-4 3.766x10-7
1 joule9.481x10-4 0.7376 1 0.2388 2.388x10-4 2.778x10-7
1 calorie0.003969 3.088 4.187 1 0.001 1.163x10-6
1 kcal 3.969 3088 4187 1000 1 0.001163
1 kwhr 3413 2.655x106 3.6x106 8.598x105 859.8 1
Power Conversions:
Foot-Pounds per second
Horse-power
calories per second
Kilo-watts
Watts
1 ft-pound per second
1 0.001818 0.3238 0.001356 1.356
1 hp 550 1 178.1 0.746 746
1 Cal per sec 3.088 0.005615 1 0.004187 4.187
1 kw737.6 1.341 238.8 1 1000
1 watt0.7376 0.001341 0.2388 0.001 1
Measurement Conversions
1 short ton (ton) = 2,000 lb = 907.19 Kg 1 metric ton (tonn) = 2,204.6 lb = 1000 Kg 1 thousand Btu (kBtu) = 1,000 Btu1 million Btu (MMBtu) = 1,000,000 Btu1 quad = 1 quadrillion Btu = 1015 Btu = 1,000,000,000 MMBtu1 kilowatt-hour (kWh) = 1,000 watt-hours1 megawatt-hour (MWh) = 1,000 kWh 1 gigawatt-hour (GWh) = 1,000 MWh
Conversions –Units:
From Kcal/Kg to Mj/Kg multiply Kcal/Kg by 0.004187From Kcal/Kg to Btu/lb multiply Kcal/Kg by 1.8
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From MJ/Kg to Kcal/Kg multiply MJ/Kg by 238.80From MJ/Kg to Btu/lb multiply MJ/Kg by 429.90
From Btu/lb to Kcal/Kg multiply Btu/lb by 0.5556From Btu/lb to Mj/Kg multiply Btu/lb by 0.002326
Conversions –Gross/Net (as per ISO, for As received figures ) Net CV = Gross CV -50.6 H -5.85 M-0.191O Kcal/Kg
Net CV = Gross CV -0.212 H -0.0245 M-0.0008O MJ/Kg
Net CV = Gross CV -91.2 H -10.5 M-0.34 O Btu/lb
(Where M- % Moisture, H-% Hydrogen, O- is % Oxygen from Ultimate analysis as received basis)
Power Generation: 1 MWh = 3600 MJ
1 MW = 1 MJ/s
1 MW (Thermal power ) [MW th ] = approx 1000 Kg steam/hr
1 MW (Electrical power ) [MWe ] = approx MW(thermal power) 3
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