Thermal Power Plants And Future Scope

B2 Batch

Contents

• Introduction and layout by Vruttiket Kadam • Operation and Site selection by Priyadarshani Marwah• Thermal power plants in india by Tawqeer Maqbool• Coal by Rohit Arora• Indian Coal by Shubham Mukharya• Liquid and Gaseous Fuels by Sarvjeet Singh• Slurry and Emulsion types of Fuels by Utkarsh Karnwal• Coal handling, storage and feeding by Rishabh and Shivang• Ash Handling by Soniya Saini• Dust Handling by Suman Patra• Comparison between power plants by Utkarsh Garg

Introduction

• A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated

• Thermal power plant - coal, nuclear, geothermal, solar thermal electric.

• In fossil-fueled power plants, steam generator refers to a furnace that burns the fossil fuel to boil water to generate steam.

• Power plant consist of – Feed water heating and de-aeration, Boiler, Super heater, Steam condensing, Re-heater, economizer, Bottom ash collection.

• The energy efficiency of conventional thermal power station is typically 33% to 48%.

• The required make up water for 500MW plant is approximately 1.25 l/s and at full load it’s upto 400 l/s.

• Application – Local area such as ship, industrial plant

Layout

• 1. Cooling tower• 2. Cooling water pump• 3. transmission line• 4. Step-up transformer • 5. Electrical generator• 6. Low pressure steam turbine• 7. Condensate pump• 8. Surface condenser• 9. Intermediate pressure steam turbine• 10. Steam Control valve• 11. High pressure steam turbine• 12. De-aerator

• 13. Feed water heater• 14. Coal conveyor• 15. Coal hopper• 16. Coal pulverizer • 17. Boiler steam drum• 18. Bottom ash hopper• 19. Super-heater• 20. Forced draught (draft) fan• 21. Re-heater• 22. Combustion air intake• 23. Economizer

• 24. Air pre-heater• 25. Precipitator• 26. Induced draught (draft) fan• 27. Flue gas stack

OPERATIONS IN A THERMAL POWER PLANT

CRITERIA FOR SITE SELECTION

OPERATIONS IN A THERMAL POWER PLANT

Principle:

Coal based thermal power plant works on the principal of  Modified Rankine Cycle.

Components of Coal Fired Thermal Power Station:

Coal Preparation In coal-fired power stations, the raw feed coal from the coal storage area is first crushed into small pieces

conveyed to the coal feed hoppers at the boilers

The coal is next pulverized into a very fine powder, so that coal will undergo complete combustion during combustion process.

Boiler and auxiliaries

T Functions of a boiler are:•To convert chemical energy of the fuel into heat energy•To transfer this heat energy to water for evaporation as well to steam for superheating.

The basic components of Boiler are: -•Furnace and Burners•Steam and Superheating

Usually, water tube boilers are used in a thermal power plant.

Economiser

It is located below the LPSH in the boiler and above pre heater. It is there to improve the efficiency of boiler by extracting heat from flue gases to heat water and send it to boiler drum.

Advantages of Economiser include

1) Fuel economy: – used to save fuel and increase overall efficiency of boiler plant.

2) Reducing size of boiler: – as the feed water is preheated in the economiser and enter boiler tube at elevated temperature, The heat transfer area required for evaporation reduces considerably.

Air Preheater

The heat carried out with the flue gases coming out of economiser are further utilized for preheating the air before supplying to the combustion chamber.

It is a necessary equipment for supply of hot air for drying the coal in pulverized fuel systems to facilitate grinding and satisfactory combustion of fuel in the furnace.

 Reheater

Power plant furnaces may have a reheater section containing tubes heated by hot flue gases outside the tubes.

Exhaust steam from the high pressure turbine is rerouted to go inside the reheater tubes to pickup more energy to go drive intermediate or lower pressure turbines.

Steam turbines

Used as prime mover in all thermal power stations. mainly divided into two groups: -•Impulse turbine•Impulse-reaction turbine

The turbine generator consists of a series of steam turbines interconnected to each other and a generator on a common shaft.

Condenser

The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped.

The functions of a condenser are:-1) To provide lowest economic heat rejection temperature for steam.2) To convert exhaust steam to water for reserve thus saving on feed water requirement.3)  To introduce make up water.

Boiler feed pump

Boiler feed pump is a multi stage pump provided for pumping feed water to economiser.

BFP is the biggest auxiliary equipment after Boiler and Turbine.

It consumes about 4 to 5 % of total electricity generation.

Cooling tower

The cooling tower is a semi-enclosed device for evaporative cooling of water by contact with air.

The cooling towers are of four types: -

1. Natural Draft cooling tower2. Forced Draft cooling tower3. Induced Draft cooling tower4. Balanced Draft cooling tower

Fan or draught system

In a boiler it is essential to supply a controlled amount of air to the furnace for effective combustion of fuel and to evacuate hot gases formed in the furnace through the various heat transfer area of the boiler.

This can be done by using a chimney or mechanical device such as fans which acts as pump.

Generator

Generator or Alternator is the electrical end of a turbo-generator set that converts the mechanical energy of turbine into electricity.

The generation of electricity is based on the principle of electromagnetic induction.

Ash handling system

The disposal of ash from a large capacity power station is of same importance as ash is produced in large quantities. Ash handling is a major problem.

Criteria for Site Selection

Transportation network: Easy and enough access to transportation network is required in both power plant construction and operation periods.

Gas pipe network: Vicinity to the gas pipes reduces the required expenses.

Power transmission network: To transfer the generated electricity to the consumers, the plant should be connected to electrical transmission system

Geology and soil type: soil and rock layers should be able to withstand the weight and vibrations of the plant.

Earthquake and geological faults: Even weak and small earthquakes can damage many parts of a power plant intensively. The site should be away enough from the faults and previous earthquake areas

Topography:  changing of a sloping area into a flat site for the construction of the power plant needs extra budget. Parameters of elevation and slope should be considered.

Rivers and floodways: should have a reasonable distance from permanent and seasonal rivers and floodways.

Water resources: For the construction and operating of power plant different volumes of water are required which is supplied from either rivers or underground water resources.

Environmental resources: Operation of a power plant has important impacts on environment. Locations that are far enough from national parks, wildlife, protected areas are selected.

Population centers: site should have enough distance from population centers.

Need for power: should be near the areas where there is more need for generation capacity, to decrease the amount of power loss and transmission expenses.

Climate: temperature, humidity, wind direction and speed affect the productivity of a power plant.

Land cover: Some land cover types such as forests, orchard, agricultural land, pasture are sensitive to the pollutions caused by a power plant.

Area size: the minimum area size required for the construction of power plant should be defined.

Distance from airports: Usually, a power plant has high towers and chimneys and large volumes of gas. Consequently for security reasons, they should be away from airports.

Archeological and historical sites: Usually historical building are fragile and at same time very valuable. Vibration caused by power plant can damage them,

THANK YOU!

Materials required1. Feed water - water circulated through closed circuit of power plant - a plant of 100 MW may require 500 tons of water per hour - 2% loss may occur2. Coal - quantity sufficient to generate steam in the boiler - calorific value of Indian coals containing 30 % ash taken as 20000 KJ/Kg

3. Cooling water - nearly 50 kg per kg of steam - nearly 2% of cooling water evaporated

4. Ash - 30- 40% ash mixed with Indian coal - harmful contents in ash, thus to be disposed off properly

5. Sulphur dioxide - highly poisonous hence its formation in combustion chamber must be avoided. - low Sulphur content coal preferred.

6. Air -large quantity of air required. - 20 kg of air required per kg of coal burnt

Requirements for 100 mw power plant

COAL FEED WATER

AIR FOR COMBUSTION

COOLING WATER

ASH SULPHUR DIOXIDE

AIR IN COOLING WATER

60 tons

10 tons 1200 tons 2500 tons

20 tons 2 tons 25000 tons

Thermal Power Stations In IndiaS no. State Power station Capacity(MW) units

1 Andhra Pradesh Kothagndam 500 2x250

2 Assam Gauhati 120 4x15, 3x20

3 Bihar Barauni 150

Bokaro 210 2x105

Patratu 400

4 Delhi Rajghat 200

Indraprashtha 350

Badarpur 300

5 Gujarat Dhuvaran 440 2x220

Ukai 240 2x120

Thermal power stations in india6 Haryana Faridabad 200

Panipat 440 4x110

7 Madhya Pradesh

Kobra 420

Satpura 300

8 Maharashtra Nagpur(koradi)

480 2x240

Nashik 280

Paras 90

9 Orissa Talcher 460 4x60,2x110

10 Tamil Nadu Neyvelli 600

Eunose 450

Thermal power stations in india

11 Uttar Pradesh Harduagan 220 1x55, 1x60, 1x105

Obra 1322 1x40, 3x94, 5x200

12 West Bengal Samtaldih 480

Chandrapur 1250 3 x 130, 3 x 120, 2 x 250

Durgapur 690 2 x 30, 1 x 70, 2 x 75, 1 x 110

Future scope of thermal power plants

• In India, current installed capacity – 135401.63MW

• Peak power shortage of 10 % and overall power shortage of 7.5%

• Proposed target to build up 100000MW by 2012 out of which 14500 MW will be renewable energy and 50MW solar energy.

• Major concentration towards Solar Thermal Power plants and Nuclear Thermal power Plants.

Future scope of thermal power plants

• India’s location favors solar energy concentration.

• annual global variation , 1600-2200 Kw/m2

• India has a flourishing and largely indigenous nuclear power program and expects to have 20,000 MWe nuclear capacity on line by 2020 and 63,000 MWe by 2032.

• It aims to supply 25% of electricity from nuclear power by 2050.

Coal

• Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams.

• It is used as fuel for thermal power plant.

Basic composition

• The main constituents are carbon, hydrogen, oxygen, nitrogen, sulphur, moisture and ash.

• Their percentages varies from different types of coal.

Classification of coal

• Peat• Lignites• Sub Bituminous• Bituminous• Anthracite• Graphite• Coke

Peat

• It is 1st stage of formation from wood• In its dehydrated form, peat is a highly

effective absorbent for fuel and oil spills on land and water.

• Uses– Domestic fuel in Europe– Power generation in Russia

Lignites or brown coal

• Intermediate stage between peat and coal.• Have high moisture, high ash and low heat

contents.• Burns with smoky flame.• The lowest rank of coal and used almost

exclusively as fuel for electric power generation.

Sub Bituminous coal

• Properties range from those of lignite to those of bituminous coal.

• Contains 15 to 20 % volatile matter and has a tendency to break into small sizes

• Uses– as fuel for steam-electric power generation– as an important source of light aromatic

hydrocarbons for the chemical synthesis industry.

Bituminous Coal

• It is dense sedimentary rock, black but sometimes dark brown often with well-defined bands of bright and dull material.

• Average calorific valve of 31350 kJ/kg.• Uses

– primarily as fuel in steam-electric power generation.

– for heat and power applications in manufacturing and to make coke.

Anthracite Coal

• The highest rank of coal is a harder, glossy, black coal.

• It is noncaking and has high % of fixed carbon.• Burns with very short blue flames or without

flames.• High calorific valve of 35500 KJ/Kg.

Graphite

• The highest rank is difficult to ignite and is not commonly used as fuel.

• Uses – mostly used in pencils– when powdered used as a lubricant.

German Classificat

ion

English Designati

onVolatiles

%C

Carbon %H

Hydrogen %

O Oxygen % S Sulfur %

Heat content

kJ/kgBraunkohle Lignite 45-65 60-75 6.0-5.8 34-17 0.5-3 <28470

Flammkohle

Flame coal 40-45 75-82 6.0-5.8 >9.8 ~1 <32870

Gasflammkohle

Gas flame coal 35-40 82-85 5.8-5.6 9.8-7.3 ~1 <33910

Gaskohle Gas coal 28-35 85-87.5 5.6-5.0 7.3-4.5 ~1 <34960

Fettkohle Fat coal 19-28 87.5-89.5 5.0-4.5 4.5-3.2 ~1 <35380

Esskohle Forge coal 14-19 89.5-90.5 4.5-4.0 3.2-2.8 ~1 <35380

Magerkohle

Non baking coal

10-14 90.5-91.5 4.0-3.75 2.8-3.5 ~1 35380

Anthrazit Anthracite 7-12 >91.5 <3.75 <2.5 ~1 <35300

Percent by weight

Properties Of Coal

• Each type of coal has a certain set of physical parameters which are mostly controlled by

• moisture• volatile content • ash• carbon content

Coal Analysis

• Basically they are of 2 types• Proximate Analysis• Ultimate Analysis

Proximate Analysis

• The objective of coal proximate analysis is to determine the amount of fixed carbon (FC), volatile matters (VM), moisture, and ash within the coal sample.

• This is done following basis– AR (as-received) basis – AD (air-dried) basis– DAF (dry, ash free) basis

For ExampleProximate Analysis

Unit (AR) (AD) (DB) (DAF)

Moisture (wt. %) 3.3 2.7 - -

Ash (wt. %) 22.1 22.2 22.8 -

Volatile Matter

(wt. %) 27.3 27.5 28.3 36.6

Fixed Carbon

(wt. %) 47.3 47.6 48.9 63.4

Gross Calorific Value

(MJ/kg) 24.73 24.88 25.57 33.13

Ultimate Analysis

• The objective of coal ultimate analysis is to determine the constituent of coal, but rather in a form of its basic chemical elements.

For ExampleProximate Analysis

Unit (AR) (AD) (DB) (DAF)

Carbon(C) (wt. %) 61.1 61.5 63.2 81.9

Hydrogen(H) (wt. %) 3.00 3.02 3.10 4.02

Nitrogen(N) (wt. %) 1.35 1.36 1.40 1.81

Total Sulphur(S) (wt. %) 0.4 0.39 0.39 -

Oxygen(O) (wt. %) 8.8 8.8 9.1 -

Coal Blending

• Coal blending in power station is mainly adopted to reduce the cost of generation and increase availability of coal.

• The low-grade coals can be mixed with better grade coal without deterioration in thermal performance of the boiler thus reducing the cost of generation.

Methods Of Blending

• Blending underground• Blending on ground level• Precision Coal Blending

Blending underground

• A tunnel equipped with a conveyor belt and specially designed scraper is employed for the coal blending operation. When different types of coal are placed in the tunnel, the scraper puts coal on the conveyor belt by moving through the tunnel.

Disadvantages

• Large underground structure• Long construction time• High investment and maintenance costs• Difficult to ensure homogeneity of blending

process• Will result in uneven burning in the boiler

Blending on ground level

• Different types of coal will be built up to a coal stock pile in horizontal layers. By vertical excavation of the coal stock the different coal types will be mixed.

Disadvantages

• Incomplete mixing process• Low quality of blending• Lacks homogeneity• Will result in uneven burning in the boiler

Precision Coal Blending

• Different types of coal are placed in each silo (of which there are usually six).

• Computer controls discharge from each silo using Extromats, and ensures the correct percentage of each type of coal falls onto a conveyor belt from each silo mixing the coal in precisely the right quantities to ensure compliant coal.

Advantages

• Reliable and consistent quality blending guaranteed within 1% of required specification

• Homogeneous blend• Controlled process• Relatively small site due to vertical nature• Ability to blend numerous types of coal with

consistent output

MAJOR COAL FIELDS AND MINING CENTERS IN INDIA

COAL SITES IN INDIA

• Large deposits of coal:1. Bengal2. Bihar3. Madhya Pradesh• Main coal fields are in:1. Ranigang2. Jharia3. Bokaro4. South Karanpur.

INTRODUCTION

• It includes 163 open cast mines, 273 underground mines and 35 mixed mines

• Coal is used by many industries such as thermal power generation, steel , cement, fertilizers, textile , chemicals and brick manufacturing

• The power generation sector in India consumed 77.0% of the total coal produced in fiscal 2009.

Proved Recoverable Coal Reserves Of India

Bituminous and Anthracite: 56100Sub Bituminous: 0Lignite: 4500Total: 60600Percentage of World: 7%Reserved life: 106 yearsIndia is the worlds forth largest importer of coal.

DIFFICULTIES OF INDIAN COAL

• Ash content in Indian coal lies between 20%-30% due to which there is reduced thermal efficiency of the plant. This occurs due to following reasons:

1. Unburnt carbon2. Excessive clinker formation3. Heat lost in ashes• Further there is difficulty in disposal of ash.

• Such high ash content coal can be used more economically I pulverized form, because it increase the thermal efficiency as high as 90% and controls can be simplified just by adjusting the position of the burners in pulverized fuel boilers.

• The recent Indian power plant are generally designed to use pulverized coal.

SELECTION OF COAL FOR THERMAL POWER PLANT

• Slow burning coal: generates high fuel-bed temperature and therefore require forced draught.

• Fast burning coal: is highly volatile and requires combustion chambers for the combustion of volatiles.

IMPORTANT FACTORS FOR SELECTION OF COAL

• Sizing,• Caking,• Swelling properties,• Ash fusion temperature,• Sulphur content also carries considerable

importance in most cases.

• Electro-static precipitator(ESP): works better with high sulphur coal because of improved resistivity of the flue gases.

• Large size coal should be used when draught is low and some moisture percentage must be maintained if the percentage of fineness in coal is high.

• Anthracite coal as fuel requires forced draught furnaces incorporating means for admitting steam to cool the fire bars and hard clinker.

SELECTION OF COAL ACCORDING TO COMBUSTION EQUIPMENT

• Sizes of coal• Ultimate and proximate analysis• Resistance to degradation• Grindability• Deterioration during storage• Caking characteristics• Slagging characteristics• Corrosive characteristics.

Liquid Fuels

Usage• Used extensively in industrial applications

Examples• Furnace oil

• Light diesel oil

• Petrol

• Kerosine

• Ethanol

• LSHS (low sulphur heavy stock)

Properties Density

• Ratio of the fuel’s mass to its volume at 15 oC,

• kg/m3

• Useful for determining fuel quantity and quality

Specific gravity• Ratio of weight of oil volume to weight of same water volume at a given temperature

• Specific gravity of water is 1

• Hydrometer used to measure

Viscosity• Measure of fuel’s internal resistance to flow

• Most important characteristic for storage and use

• Decreases as temperature increases

Flash point• Lowest temperature at which a fuel can be heated so that the vapour gives off

flashes when an open flame is passes over it

• Flash point of furnace oil: 66oC

Pour point• Lowest temperature at which fuel will flow

• Indication of temperature at which fuel can be pumped

Specific heat• kCal needed to raise temperature of 1 kg oil by 1oC (kcal/kgoC)

• Indicates how much steam/electricity it takes to heat oil to a desired temperature

Calorific value• Heat or energy produced

• Gross calorific value (GCV): vapour is fully condensed

• Net calorific value (NCV): water is not fully condensed

Sulphur content• Depends on source of crude oil and less on the refining process

• Furnace oil: 2-4 % sulphur

• Sulphuric acid causes corrosion

Ash content• Inorganic material in fuel

• Typically 0.03 - 0.07%

• Corrosion of burner tips and damage to materials /equipments at high temperatures

Carbon residue• Tendency of oil to deposit a carbonaceous solid residue on a hot

surface

• Residual oil: >1% carbon residue

Water content• Normally low in furnace oil supplied (<1% at refinery)

• Free or emulsified form

• Can damage furnace surface and impact flame

Storage of fuels

• Store in cylindrical tanks above or below the ground

• Recommended storage: >10 days of normal consumption

• Cleaning at regular intervals

Furnace Oil

• Furnace oil is a dark colored fuel, either distilled or residual fraction of crude oil that is extracted while petroleum distillation and is used for the purpose of generation heat and power.

• This fuel is sticky, thick and glutinous in nature. • Furnace oil is known by the name of fuel oil internationally

and also as bunker fuel. • The fuel oil consists of lengthy chains of hydrogen and

carbon mainly alkanes, cycloalkanes and aromatics. • Basically furnace oil is termed for relatively heavier

commercial extracts from crude oil.

• Uses of Furnace Oil:– As fuel for Power Generation in DG Sets – As fuel for Boilers/ Furnaces/ Air preheater/ Any other

Heaters As fuel for Bunkering As fuel/ Feedstock in Fertilizer Plants

• Advantages:– Low sulphur fuels will emit lesser quantity of sulphur

dioxide and thus cause minimal environmental pollution.

– Low sulphur fuels will not cause corrosion effect on the equipments used, at low and high temperatures, thus increasing the life expectance of such equipments.

Light Diesel Oil (LDO)

• Light Diesel Oil falls under class C category fuel having flash point above 66OC.

• It is a blend of distillate components and a small amount of residual components.

• Uses of Light Diesel Oil (LDO) :– As fuel for lower RPM engines – As fuel for Lift irrigation pumpsets and DG sets – As fuel for certain boilers and furnaces

Superior Kerosene Oil (SKO)Kerosenes are distillate fractions of crude oil in the boiling range of 150-

250°C. They are treated mainly for reducing aromatic content to increase their

smoke point (height of a smokeless flame) and hydrofining to reduce sulphur content and to improve odour, colour & burning qualities (char value).

Uses of Superior Kerosene Oil (SKO):As illuminant in various lamps As fuel in cooking stoves/ranges, ovens, blow lamps As cleaning fluid /degreasing components As solvent in paints/printing inks As raw material for the manufacture of paraffins As a low sulphur fuel in boilers

/furnaces

Low Sulphur Heavy Stock (LSHS)

Low Sulphur Heavy Stock (LSHS) is a residual fuel processed from indigenous crude. This fuel is in lieu of FO in the same applications where furnace oil is suitable.

The main difference with LSHS and FO is in the form of higher pour point, higher calorific value and lower sulphur content in LSHS.

As this fuel has higher pour point than that of FO it requires special handling arrangements. LSHS is handled hot at all stages and is maintained at 75OC. Special care is also taken so that no 'boil over' of the product takes place in the storage

Uses of Low Sulphur Heavy Stock (LSHS):

• As fuel for Power Generation in DG Sets • As fuel for Boilers/ Furnaces/ Air preheater/

Any other Heaters • As fuel for Bunkering As fuel/ Feedstock in

Fertilizer Plants

Typical specifications of fuel oils

Properties Fuel Oils

Furnace Oil L.S.H.S L.D.ODensity (Approx. g/cc at 150C)

0.89-0.95 0.88-0.98 0.85-0.87

Flash Point (0C) 66 93 66

Pour Point (0C) 20 72 18

G.C.V. (Kcal/kg) 10500 10600 10700

Sediment, % Wt. Max.

0.25 0.25 0.1

Sulphur Total, % Wt. Max.

< 4.0 < 0.5 < 1.8

Water Content, % Vol. Max.

1.0 1.0 0.25

Ash % Wt. Max. 0.1 0.1 0.02

Gaseous Fuels

Classification of gaseous fuelsA) Fuels naturally found in nature

- Natural gas- Methane from coal mines

(B) Fuel gases made from solid fuel- Gases derived from coal- Gases derived from waste and biomass- From other industrial processes

(C) Gases made from petroleum- Liquefied Petroleum gas (LPG)- Refinery gases

Natural gas

• Methane: 95%

• Remaining: 5%: ethane, propane, butane, pentane, nitrogen, carbon dioxide, other gases

• High calorific value fuel

• Does not require storage facilities

• No sulphur

• Mixes readily with air without producing smoke or soot

Methane

• Methane is a colourless, odourless gas with a wide distribution in nature.

• It is the principal component of natural gas, a mixture containing about 75% CH4, 15% ethane (C2H6), and 5% other hydrocarbons, such as propane (C3H8) and butane (C4H10).

• The "firedamp" of coal mines is chiefly methane.• Anaerobic bacterial decomposition of plant and animal

matter, such as occurs under water, produces marsh gas, which is also methane.

Liquefied Petroleum Gas (LPG)

Propane, butane and unsaturates, lighter C2 and heavier C5 fractions

Hydrocarbons are gaseous at atmospheric pressure but can be condensed to liquid state

LPG vapour is denser than air: leaking gases can flow long distances from the source

Slurry Fuel

• Coal-water slurry fuel (CWSF or CWS or CWF) is a fuel which consists of fine coal particles suspended in water.

• CWS consists of 55-70% of fine dispersed coal particles and 30-45% of water. Coal particles suitable for diesel fuel replacement typically need to be less than 20 micrometres in diameter.

History• Toward the end of 1950s, the Soviet Union started the development of new

ways to utilize coal sludge for power generation. Two major problems of sludge transportation and sludge combustion were solved during the series of experiments and research.

• Ball mills pulverize and mix the coal sludge with water producing coal-water slurry (mix of liquids and hard particles). CWS produced by milling the sludge and/or regular coal near the coal mine near Belovo (Siberia, Russia) was transported through the pipeline to Novosibirsk (Siberia, Russia), a distance of 262 km.

• The unique difference of project Belovo-Novosibirsk uses CWS directly for combustion in steam boilers at a rate of 1340 tons/hr. In other world projects CWS was used only for transportation which was followed then with drying of CWS before the combustion of the pulverized coal.

• Since the 2004 Russia has continued the development and implementation of CWS technology for heating stations (for district heating) and power stations.

Preparing CWSCoal of almost any types could be used as a raw for WCF: lignite, flame

and gas flame coals, anthracites.

CWS preparation consists of three major stages:1. Prior crushing till 10 to 25 micrometers or 60 to 65 micrometers2. Wet milling and homogenization3. Intermediate storage

Standard crushers could be used for prior crushing of raw coal. On the wet milling and homogenization stage coal is milling and mixing with water and (if required) some additives. Countries like Russia have developed high efficient and low consumption method of wet milling and homogenization what reduces energy expenses for production of each ton of CWS plus avoids using of additives which makes Coal Slurry stable.

Combustion of CWS

CWF can be used in several different applications, in the largest particle form it is a viable substitute for heavy grade fuel oils used to produce steam in boilers. Low speed marine or modular powerplant diesels can operate on pure CWF.

For gas turbine testing CWF particles five to ten micrometres in size have been used to demonstrate useful substitution for petroleum or natural gas in combined cycle gas turbine powerplant applications.

The smaller the particle size the more versatile the CWF is for application, however the finer the particle size the more difficult it is to manufacture.

Benefits• The presence of water in CWS reduces harmful

emissions into the atmosphere and makes the coal explosion-proof.

• Presence of water in CWS reduces harmful emissions into the atmosphere, makes the coal explosion-proof, makes use of coal equivalent to use of liquid fuel (heating oil) and gives other benefits.

Emulsion Fuel

• Emulsified Fuels are emulsions composed of water and a combustible liquid, either oil or a fuel.

• Emulsions are a particular example of a dispersion comprising a continuous and a dispersed phase. In the case of emulsions both phases are the immiscible liquids, oil and water.

Types of Emulsions

Microemulsion Macroemulsion• Stability-

Microemulsions are thermodynamically stable systems.

• Particle Size- Microemulsions are formed spontaneously and have dimensions of 10 to 200 nm.

• Microemulsions are isotropic.

Stabillity- Macroemulsions are kinetically stabilized.

Particle Size- Macroemulsions are formed by a shearing process and have dimensions of 100nm to over 1 micrometer.

Macroemulsions are prone to settling (or creaming) and changes in particle size over time.

Different types of Emulsions

• Water-in-oil (invert emulsions).

• Oil-in-water (regular emulsions).

Water-in-oil Emulsion Fuel• Surfactant based emulsion is a water-in-oil

emulsion fuel consisting of from 5 percent to 10 percent water dispersed as droplets in a continuous oil phase.

• The key to achieving maximum combustion with this fuel is producing water droplets in the range of 5 microns to 20 microns in diameter within the oil.

• This is accomplished by introducing a small amount of surfactant (PEP-99™) to control water droplet size and prevent coalescence. Proper mixing and proportioning of the water, oil and surfactant creates a very stable emulsion that is ready to burn.

• A typical burner atomizer produces a spray of fuel oil droplets around 100 microns to 200 microns in diameter, depending on fuel quality and atomizer design.

• Large fuel droplets do not completely burn, leaving unburned carbon to collect on heat transfer surfaces and escape as particulate matter in the exhaust gases. This reduces overall thermal efficiency.

• In the combustion of a water-in-oil emulsion, the primary spray fuel droplets are further divided as a result of the explosive vaporization caused by rapid heating of the water dispersed within the individual fuel droplets. The internal water droplets undergo spontaneous nucleation of steam bubbles at a temperature well above 100oC, causing a violent conversion of the water droplet to steam. The vaporization, in turn, produces a rapid expansion of the surrounding oil droplets, fragmenting the oil into a vast number of smaller fuel droplets. The name for this process is secondary atomization.

• If the number of water droplets is too small (1 micron or less), insufficient energy will be produced to cause secondary atomization. On the other hand, larger droplets (10 microns or larger) reduce the number of droplets for explosion and tend to produce less violent explosions.

Oil-in-water Emulsion fuel

• Most oils are less dense in water, and if oil and water are mixed then the oil will simply float to the surface.

• In emulsions, the oil is dispersed as liquid droplets through the continuous phase, usually but not necessarily water.

Contd. This means that an emulsion is thermodynamically unstable. Those droplets want to

combine together again to form a single blob of oil. To prevent them from doing this, emulsions contain a surfactant which coats the surface of each drop and prevents the droplets from coalescing.

However the oil is still less dense than the water. So each drop is prone to floating upwards. This process is called creaming - the oil droplets will gradually form a dense layer at the top of the sample.

To prevent creaming, many emulsion products contain additives called stabilizers that inhibit creaming. Stabilizers work by increasing the viscosity of the continuous phase in which the oil droplets are immersed, or by inducing some kind of interaction between droplets.

Benefitsimproved atomizationimproved carbon burnout lower S03 formationLower V2O5 formationreduced back-end foulingreduced back-end corrosionelimination of fireside additiveslower particulatelower NOx lower 02

shorter flame lengthreduced flame impingementimproved heat transferreduced soot blowingreduced acid mistreduced boiler maintenance including downtime

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1. Coal Handling2. Coal Storage3. Coal Preparation4. Coal Feeding

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Schematic representation

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Coal Handling

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Coal handling via Conveyor

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COAL HANDLING (cont)

• Coal needs to be stored at various stages of the preparation process, and conveyed around the CPP facilities.

• Coal handling is part of the larger field of bulk material handling, and is a complex and vital part of the CPP.

• Types of handling system1. Conveyor2. Shipment3. Trucks

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Coal Storage

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Types of coal storage

StockpilesStockpiles provide surge capacity to various parts of the CPP. ROM coal is delivered with large variations in production rate of tonnes per hour (tph). A ROM stockpile is used to allow the wash plant to be fed coal at lower, constant rate.

StackingTravelling, lugging boom stackers that straddle a feed conveyor are commonly used to create coal stockpiles.

ReclaimingTravelling, lugging boom stackers that straddle a feed conveyor are commonly used to create coal stockpiles.

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Coal Preparation

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Hammer Rings for Coal Crushing

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Methods of coal preparation

• CrushingCrushing reduces the overall top size of the ROM coal so that it can be more easily handled and processed within the CPP. Crushing requirements are an important part of CPP design and there are a number of different types.

• ScreeningScreens are used to group process particles into ranges by size. These size ranges are also called grades. Dewatering screens are used to remove water from the product. Screens can be static, or mechanically vibrated. Screen decks can be made from different materials such as high tensile steel, stainless steel, or polyethylene.

• Gravity separationGravity separation methods make use of the different relative densities of different grades of coal, and the reject material.

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Coal Feeding by paddle feeder

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Coal feeding gravimetric feeder

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Methods of coal feeding

• Gravimetric coal feederHere the coal separation takes place in the rolling mill. After the coal passes the mill, it falls in stroking area where it is fed to the FBC boilers due to gravitational force

• Paddle Feeder.To scoop the raw coal from the table below the Track hopper to the respective conveyor; generally two feeders are provided on each side with in a Track hopper; when not in use they are parked on either side;

A huge quantity of ash is produced in Power Plants, sometimes being as much as 10 to 20% of the total quantity of coal burnt in a day.Handling of ash includes:

• Its removal from the furnace.• Loading on the conveyors and delivery to the

fill or dump from where it can be disposed off.

Ash Handling Introduction

Handling of ash is a problem because:• Ash coming out of the furnace is too hot• It is dusty • It is irritating to handle • It is accompanied by some poisonous gases.

Ash needs to be quenched before handling due to following reasons:

• Quenching reduces corrosion action of ash.• It reduces the dust accompanying the ash. • It reduces the temperature of the ash.• Ash forms clinkers by fusing in large lumps and

by quenching clinkers will disintegrate.

Quenching of ash

• The plant should be able to handle large clinkers, boiler refuse, soot and dust with minimum attention of operators.

• It should have enough capacity to cope with the volume of ash that may be produced in the station.

• The plant should not cost much and the operating and maintenance charges should also be minimum.

Principal Requirements of Ash Handling Plant

• The operation of the plant should be noiseless as much possible.

• The plant should be able to operate efficiently under all variable load conditions.

• It should be able to handle hot and wet ash effectively.

• In case of addition of units, it should need minimum changes in original layout of plant.

The modern ash handling systems are mainly classified into four groups:

• Mechanical Handling System• Hydraulic System • Pneumatic System• Steam Jet System

Ash Handling Systems

Mechanical Handling System

• Used for low capacity power plants using coal as a fuel.

• The hot ash coming out of boiler furnace is made to fall over the belt conveyor through a water seal.

• The cooled ash falls on the belt conveyor and it is carried continuously to the overhead bunker.

• Ash is carried to the dumping site from the ash bunker with the help of trucks.

• The control valve is opened and closed manually to load the truck.

• Life of this system is 5 to 10 years.• Maximum capacity is limited to 5 tons per

hour.• Major advantage of this system is low power

consumption.

In this system ash is carried with the flow of water with high velocity through a channel and finally dumped in the sump.The system is subdivided as follows:

• Low Pressure System• High Pressure System

Hydraulic Ash Handling System

Low Pressure System

• In this system a trough or drain is provided below the boilers and the water is made to flow through the trough.

• The ash directly falls into the troughs and is carried by water to sumps.

• In the sump the water is separated from ash by making the mixture pass through a screen.

• This water is pumped back to the trough for reuse and ash is removed to the dumping yard.

• The ash carrying capacity is 50 tonnes/hour and distance covered is 500 meters.

High Pressure System

• The hoppers below the boilers are fitted with water nozzles at the top and on sides.

• The top nozzles quench the ash while the side ones provide the driving force for the ash.

• The cooled ash is carried to the sump through the trough.

• The water is separated from ash and recirculated.

• Capacity is 120 tonnes/hour and distance covered is 1000 meters.

• The system is clean, dustless and totally enclosed.• It can be used to handle stream of molten ash.• Working parts do not come in contact with the ash.• The unhealthy aspects of ordinary ash basement

work is eliminated.• Its ash carrying capacity is considerably large,

hence suitable for large thermal power plants.• It can discharge ash at a considerable distance

(1000m) from the power plant.

Advantages

• These systems can handle abrasive ash as well as fine dusty materials such as fly-ash and soot.

• It is preferable for the boiler plants from which ash and soot must be transported some far off distance for final disposal.

Pneumatic System

• The exhauster provided at the discharge end creates a high velocity stream which picks up ash and dust from all discharge points and then these are carried in the conveyor pipe to the point of delivery.

• Large ash particles are generally crushed to small sizes through mobile crushing units which are fed from the furnace or hopper and discharge into the conveyor pipe which terminated into a separator at the delivery end.

• The separator working on the cyclone principle removes dust and ash which pass out into the ash hopper at the bottom while clean air is discharged from the top.

• The ash carrying capacity varied from 25 to 15 tons per hour.

• No spillage and re-handling.• High flexibility.• There is no chance of ash freezing or sticking in

the storage bin and material can be discharged freely by gravity.

• The ductless operation is possible as the materials are handled totally in an enclosed conduit.

• The cost of plant per tonne of ash discharged is comparatively less.

Advantages

• There is a large amount of wear in the pipe work necessitating high maintenance charges.

• More noisy than other systems

Disadvantages

• In this system steam is passed through a pipe at sufficiently high velocity which is capable of carrying dry solid materials of considerable size along with it.

• In a high pressure steam jet system, a jet of high pressure steam is passed in the direction of ash travel through a conveying pipe in which the ash from the boiler ash hopper is fed.

• The ash is deposited in the ash hopper.

Steam Jet System

• Less space requirements.• Less capital cost in comparison to other

systems.• Auxiliary drive is not required.• The equipment can be installed in awkward

position too.• Ash can be removed economically through a

horizontal distance 200 meters and through a vertical distance of 30 meters.

Advantages

• Noisy Operation.• The system necessitates continuous operation

since its capacity is limited to about 7 tonnes per hour.

• Due to abrasive action of ash the pipes undergo greater wear.

Disadvantages

• Vacuum Extraction Plant: This system is disposal is used on both stoker and pulverised fuel installations and give good service.

• Water Ejector System: This system can also be used with stoker as well as with pulverised fuel-fired boilers with equal efficiency. Its adaption is more economical if the high pressure water is used for the system.The dust is periodically extracted from the dust hoppers by the water ejector and discharged into a sluiceway in the form of slurry. Its capacity is 60 to 80 tons per hour.

Ash Disposal

• Steam Ejector System: This system is also used to carry the dust to the disposal site.

• Mechanical Conveyors: The dust is also carried by mechanical conveyors like screw and belt provided it is wetted before carrying.

The ash and dust is transported using one of the two systems:

• Wet System• Dry System

• In the wet system, ash is transported to ash ponds in form of a slurry.

• As ash settles in the pond, the part of the water evaporates and the remainder is either recycled or impounded.

• This system requires installation of pipelines and construction of embarkments.

Wet System

• Transportation of ash by pipelines eliminates noise, dust and traffic problem.

• Use of manned equipment is eliminated.• The system is unaffected by transportation

strikes.

Advantages

• Large quantities of leachate under a positive pressure head in pond pose a constant threat to ground water quality. This is prevented by surface preparation and artificial lining which are very costly.

• Larger area is required. Area of wet system may be twice of the dry area.

• Scaling and cementation within pipeline.

Disadvantages

• In the dry system, ash is transported to the disposal site in a relatively dry state (in the form of a paste).

• Water is added only to compact the ash.• It does not require embankments to hold ash.• Compacted ash surfaces are covered with top

soil and seeded.

Dry System

• Leachate quantities are significantly reduced.• Water and power consumptions are very less.• Compacted ash is a structural material which

can be sold.• This system offers greater flexibility in

operation as ash is transported by vehicles to different sites.

Advantages

• Use of trucks make this system totally dependent.

• It presents increased visual impact along transportation route.

• Wetting of ash containing calcium or magnesium forms lumps which may stick to the conveying belt.

Disadvantages

• The presence of excess ash seriously reduces the boiler capacity, because sufficient coal cannot be burnt on the grates to do the necessary work.

• The ash produced is abrasive and will wear out the conveying parts on contact with it.

• When ash forms clinkers, it is very difficult to remove from the grate.

• The molten ash may also accumulate on the walls of furnace and on boiler surface which corrodes the boiler parts and also hampers heat transfer.

Ash and its effects on Boiler operation and performance

Dust Handling Contents

• Dust collection• Classification• Mechanical dust collector• Wet dust collector• Performance of dust collector• Installation of dust collector

Dust collection & its disposal

• Dust collection is done because – Most of the Indian coal contains 30% to 45% of ash– It contains only 1% to 1.5% of sulpher.– Contains large percentage of silica.

• It is necessary to clean the gas streams contaminated with particle.

• Dust or these contaminated gas affect the atmosphere leading to pollution.

• There effect can be seen in the form of acid rain , thick fog formation and green house effect etc.

Classification

Gas Cleaning device

Mechanical Dry typeGravitational

Separator

Cyclone separator

Wet type Spray type

Packed type

Impingement typeElectrical

Rod type

Plate type

Mechanical dust collector

• Cyclonic collectors, fabric filters, electronic precipitators, wet scrubbers and combination of all may help to reduce the emissions from coal fired boilers

Gravitational Seperators

• Separating the dust particles with help of gravity.

• Different methods are:1. in the cross sectional area 2. Changing the direction of the gas flow 3. Impingement of gas stream on baffels

Bag house duct collector

• Are designed to collect 99.9% of dust particle (particle size above 1µ)

• Are more sensitive to consideration of objectionable gases.

• the temperature of the hot gas passing through bag house can be controlled by cold air bypass.

• Presently used bag fabric filters are impregnated with teflon.

Advantages

• Not sensitive to flashy resistivity.• High collection efficiency.• Less costlier

Disadvantages

• Sensitive to fluctuating temperature

Pulse- jet dust collector

• Can be used for high temperature applications in coal –fired boiler.

• Fabric filters contains of large box with suspended filter bag

Cyclon seperator

• A high velocity gas stream carrying dust particle enter tangentially to the conical shell.

• This produce a whirling motion of the gas within chamber and throws heavier particle to side, falls out to collector at bottom.

Advantage

• More rugged so maintenance cost is low• Efficiency is higher.• Efficiency increases with increases of load

Disadvantages• Incapable of removing dust and ash particles which remains in

suspension• Requires more power than other collector.• Is not flexible.• Cannot remove fine dust particles.

Electrostatic precipitators

• Used in removal of fly-ash from electric utility boiler emissions.

• Designed to operate at any desired efficiency

Working principle

• Dust laden is passed between oppositely charged conductors and become ionized.

• Once the dust is charged it is passed through dust collecting plates.

• There the plates are charged as electrode, where dust particles get separated and clean air goes out.

Advantages

• Effective to remove very small particle • Effective to remove high dust loaded gas• The draught loss of this separator is the least

of all • Low maintenance charge.• Ease to operate.• Dust is collected in dry form.

Disadvantages

• Direct current is not available with modern power plant.

• Running charge are also high • Space required is larger than wet system.

Wet type

• Used for control of emission of SO2 by using scrubbers.

• The gases and fumes are dissolved in the liquid(water + lime) which is spread in the dust collector.

• Mixture in the form of thick fluid from bottom of the collector.

• Cleaned flue gases go out from top.

• While mixing , the fine slow moving droplets collide with the wet dust particles.

• Wetted particles agglomerate until heavy enough to drop out of the gas stream.

Performance of dust collectors

– Effect of particle size – Velocity on the collection efficiency– Power requirement with an increase in load

• MECHANICAL COLLECTOR(DRY):– Efficiency with an in dust particle size.– Efficiency with an in gas velocity.– Draught loss with an in gas velocity and power

required

• WET COLLECTORS– Efficiency with an in relative velocity between

water and gas and quantity of water.– Efficiency with an in size of the dust particles– Power requirement with an in relative velocity.

• ELECTROSTATIC PRECIPITATOR– Efficiency is least affected by particle size– Efficiency highly affect due to in gas velocity.

Installation of collector

• Installed either before air-heater or after air-heater.

• installed between boiler outlet and the chimney but on the chimney side of air-heater

• Advantage of the above is that it reduces the cleaning charges.

• Installed after air heater, the heat utilized for heating the air will be more

• Installation of electric collector to hot side is more preferable and economical

• But in the western power plant the electrostatic precipitators do not function because of use of low sulpher contain coal.

• According to placement of the electrostatic precipitator :– Hot side arrangement– Cold side arrangement

COMPARISION BETWEEN POWER PLANTS.

BY:UTKARSH GARGPRN:08070121431

CONTENTS

• INTRODUCTION

• CHART REPRESENTATION

• CLASSIFICATION

• ADVANTAGES

INTRODUCTION

• A power plant is an industrial facility for the generation of electric power.

• Nearly all power stations consist of a generator, a rotating machine that converts mechanical power into electrical power by creating relative motion between a magnetic field and a conductor.

CHART REPRESENTATION POWER PLANT

RAW MATERIAL

SITE SELECTION

CAPACITY EFFICIENCY COST(APPROX)

DRAWBACKS

THERMAL FOSSIL FUELS

STABLE LAND

500-3500MW

33-48% US$ 1-1.5 billion

COSTLY AND POLLUTION

NUCLEAR URANIUM-235

ISOLATED AREA

400-2000MW

20-35% US$ 2 billion

WASTE DISPOSAL

SOLAR SUN’S HEAT MAX. SUN RAYS

50-350MW VERY LESS US$ 1billion

LESS EFFICIENT AND HIGH COST

HYDRO-ELECTRIC

WATER CLOSE TO A WATER BODY

2000-22000MW

80-90% US$ 1 billion

MASSIVE AREA REQUIRED FOR SET UP

DIESEL DIESEL CAN BE SET UP ANYWHERE

8-2000KW 46-52% US$ .25 billion

ONLY USED FOR SMALL APPLICATIONS

THERMAL POWER PLANT

• These power plants generate electrical energy from thermal energy (HEAT).

• Since heat is generated by burning fossil fuels like coal, petroleum, or natural gas, these power plants are also collectively referred to as the fossil fueled power plants.

SITE SELECTION

• Geology and soil type

• Gas pipe network

• Water resources

• Climate

• Population centres

ADVANTAGES

• The fuel used is quiet cheap

• Less initial cost

• Less space required as compared to hydroelectricpower plant

• Cost of generation is less

NUCLEAR POWER PLANT

• Nuclear power plants work on the chemical process of fission.

• Nuclear power plants have ways to control or stop these reactions when they seem to go out of control and become threatening.

• The nuclear fuel used in the nuclear power plants are Uranium-235 or Plutonium-239.

SITE SELECTION

• Disposal of Waste

• Distance from populated areas

• Availabilty of Water

ADVANTAGES

• Almost negligible emissions• A small amount of matter creates a large

amount of energy• Nuclear power is reliable. This technology is

readily available; it does not have to be developed first.

• Nuclear power is also not so expensive as compare to power from coal

The difference between thermal and nuclear power generation

HYDRO POWER PLANTS

• These plants use the kinetic energy of flowing water to produce electrical energy.

• Hydro power plants store water in large reservoirs.

• Despite their utility, the major drawback of hydro power plants is that they are highly dependent on the hydrological cycle of the area where they are built.

ADVANTAGES

• Less pollution

• Renewable source of energy

• Cheap electricity produced

• Automated plants

SOLAR POWER PLANT• Solar energy is one of the most abundant natural

resources that is capable of providing more power than the current demand requires.

• Most of the solar power plants are concentrating solar power plants in which the rays of the sun are concentrated into a single beam using lenses and mirrors.

• In these plants, Sunrays are concentrated on photovoltaic surfaces which convert the Sun's energy into electrical energy using the photoelectric effect.

WHY LESS EFFICIENT ?

• The main reason because of which solar power plant is less efficient is because of its low conversion rate of the suns rays to electricity using photovoltaic cells.

• These cell convert less than 7% of the suns energy into electricity.

• The major disadvantage being that these cells are very expensive and increase the cost.

DIESEL POWER PLANT

• A diesel generator is the combination of a diesel engine with an electrical generator,often called an alternator to generate electrical energy.

• Diesel generators, sometimes as small as 200 kW are widely used not only for emergency power, but also many have a secondary function of feeding power to utility grids either during peak periods, or periods when there is a shortage of large power generators.

THANK YOU

Thank you