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

25

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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