conventional power generation

8/10/2019 Conventional Power Generation

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Vineet Kumar

Energy & Mining


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Globally 60% of total power generation is done through

Thermal power stations.

Main parts of the plant are:

1. Coal conveyor 2. Pulverizer

3.Boiler 4. Stroker

5. Electrostatic Precipitator6. Smoke stack 7. Turbine

8. Condenser

9. Transformers 10. Cooling towers

11. Generator 12. Transformers

OVERVIEW


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COAL CONVEYOR :This is a belt type arrangement which is used to transport coal

from storage units in the power plant to the nearby boiler.

STOKER :The coal which is brought to the nearby boiler has to be put into

the boiler furnace for combustion. This stoker is a mechanical

device for feeding coal to the furnace.

PULVERIZER:The coal is put in the boiler after pulverization. For this pulverizer

is used. A pulverizer is a device for grinding coal for combustion in

a furnace of the power plant .


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BOILER:Pulverized coal is put in boiler furnace in which water is heated

and circulated until the water is turned in to steam at the required

pressure. Coal is burned inside the combustion chamber of boiler.

These gases which are at high temperature vaporize the water

inside the boiler to steam.

CONDENSER :

Steam after rotating steam turbine comes to condenser.

Condenser refers here to the shell and tube heat exchangerinstalled at the outlet of every steam turbine in Thermal power

stations. These condensers are heat exchangers which convert

steam from its gaseous to its liquid state. In so doing, the latent

heat of steam is given out inside the condenser .


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COOLING TOWERS :

The condensate water after condensation is initially at hightemperature. This hot water is passed to cooling towers. It is

a tower in which atmospheric air circulates in direct or indirect

contact with warmer water and the water is thereby cooled.

Water, acting as the heat-transfer fluid, gives up heat to

atmospheric air, and thus cooled, is recirculated through the

system.

ECONOMISER :

Flue gases coming out of the boiler carry lot of heat. Function ofeconomiser is to recover some of the heat from the heat carried

away in the flue gases up the chimney and utilize for heating the

feed water to the boiler. It is placed in the passage of flue gases in

between the exit from the boiler and the entry to the chimney.


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ELECTROSTATIC PRECIPITATOR :

It is a device which removes dust or other finely divided particles

from flue gases by charging the particles inductively with an

electric field, then attracting them to highly charged collector

plates.

SMOKE STACK (CHIMNEY) :

A chimney is a system for venting hot flue gases or smoke from

a boiler, stove, furnace or fireplace to the outside atmosphere.They are typically almost vertical to ensure that the hot gases flow

smoothly, drawing air into the combustion through the chimney

effect.


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GENERATOR:

A generator is an electromechanical device that converts

mechanical energy to alternating current electrical energy. Most

generators use a rotating magnetic field. Any AC generator can be

called an alternator, but usually the word refers to small rotating

machines driven by automotive and other internal combustionengines.

TRANSFORMERS :

It is a device that transfers electric energy from one alternating-current circuit to one or more other circuits, either increasing

(stepping up) or reducing (stepping down) the voltage


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OVERVIEW

Hydro electric power plants harness power from water under

pressure to generate power.

Nearly 30% of the total power generated by world is met by

hydro electric.

Nearly 3288 TWh of potential is available globally.


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SELECTION OF SITE

The site for Hydraulic power plant is selected considering the

following factors

Water availability Water storage facilities

Head of water

Distance from load center

Accessibility of the site


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SCHEMATIC OF HYDRO ELECTRIC POWER PLANT


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COMPONENTS OF HYDRO ELECTRIC POWER PLANT

Reservoir

Dam

Fore bay

Waterway

Draft tube

Surge tank

Spillway

Power house and equipment.


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WATER RESERVOIR

Reservoir is used to store water behind the dam which is

utilized by hydro electric plant to generate electricity.

Reservoir may be natural or artificial.

Water held in the upstream reservoir is called storage and

water behind the dam at the plant is called pondage.


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DAMS

A Dam is a masonry structure built at a suitable location

across a river.

The primary function of the dam is to provide the head of

water.

Dams are classified based on:

Function

Shape Construction materials

Design


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FOREBAY

Forebay acts as a temporary regulating reservoir

The forebay has the following parts:

Entrance bay

Spillway

Screens

Valve chamber

Penstock inlet


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TRASH RACK

It is provided for preventing the debris from getting into the

intakes from the dam or from the forebay to the turbines

Trash rack is generally made up of steel bars


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WATERWAY

A waterway is used to carry water from the dam to

powerhouse.

It includes canal, penstock and tunnel

Tunnel is the passage created by cutting a mountain to reduce

the length of the waterway to the power house.

A canal is an open structure constructed on earth or rock.


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Penstock is a pipe which carries the water from reservoir to

turbine house

Penstock is made up of steel or reinforced concrete

Penstock should be sloping towards the powerhouse

Sharp bends should be avoided and generally require special

anchorages

The intake of the penstock should be at a low level to provide

adequate water seal under all conditions

PENSTOCK


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SURGE TANKS

Surge tank is a storage reservoir fitted to a penstock .

It controls the pressure variations resulting from the rapid change

in water flow from penstock and thereby prevents water hammer

effects.

Its function is to control water when load on turbine decreases

and supplies water when the load on the turbine increases.


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In the powerhouse conversion of energy of water to electrical

energy takes place.

It has the following equipments Turbines

Generators

Relief valve for penstock fittings

Transformers Flow measurement equipments

POWER HOUSE AND EQUIPMENT


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TURBINES

Hydraulic turbines are classified into two types they are

Impulse turbines

Reaction turbines

The impulse turbines are used for high head power plants and

reaction turbines are used for low and medium head power

plants.


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ADVANTAGES OF HYDRO ELECTRIC POWER PLANTS

Water is cheapest and a reliable source of generation of

electric power

Its maintenance cost is low

No fuel transportation problem

Running cost of plant is low

In addition to power generation it is used for irrigation and

flood control purposes


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DISADVANTAGES OF HYDRO ELECTRIC POWER PLANT

The power produced by the plant depends upon quantity of

water in the dam and prevailing rainfall in the region

The cost of transmission is high

Erection of the plant is cumbersome and time consuming


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Nuclear fuel is any material that can be consumed to

derive nuclear energy. The most common type of nuclear

fuel is fissile elements that can be made to undergonuclear fission chain reactions in a nuclear reactor

The most common nuclear fuels are 235U and 239Pu

NUCLEAR FUEL


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When a neutron strikes an atom of uranium, the uranium

splits into two lighter atoms and releases heat energy

Fission of heavy elements is an exothermic reaction which

can release large amounts of energy both as

electromagnetic radiation and as kinetic energy of the

fragments

NUCLEAR FISSION


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A nuclear reactor is a device in which nuclear chain

reactions are initiated, controlled and sustained at a steady

rate, as opposed to a nuclear bomb, in which the chain

reaction occurs in a fraction of a second and is

uncontrolled, hence causing an explosion.

NUCLEAR REACTOR


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Control rods are made of a material that

absorbs neutrons and are inserted into the

bundle using a mechanism that can rise or

lower the control rods

The control rods essentially contain

neutron absorbers like, boron, cadmium or

indium.

CONTROL RODS


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Steam generators are used to convert water into steam from heat

produced in a nuclear reactor core

Either ordinary water or heavy water is used as the coolant

STEAM GENERATORS


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A steam turbine is a mechanical device that extracts mechanical

energy from pressurized steam and converts it into useful

electrical energy

Various high-performance alloys and super alloys are used for

turbine fabrication

STEAM TURBINE


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The coolant pump pressurizes the coolant

to pressures of 155bar

The pressure of the coolant loop is kept

constant with the help of the pump and a

pressurization unit

COOLANT PUMP


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Steam coming out of the turbine flows

through the condenser for condensation and

is re-circulated for the next cycle of operation

The feed pump circulates the condensed

water in the working fluid loop

FEED PUMP


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Condenser is a device or unit which is used to condense

vapor into liquid

The objective of the condenser is to reduce the turbine

exhaust pressure to increase the efficiency and to recover

high quality feed water in the form of condensate & feed it

back to the steam generator without any further treatment

CONDENSER


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Cooling towers are heat removal

structures used to transfer processed

waste heat to the atmosphere

Water circulating through the condenser

is taken to the cooling tower for cooling

and reuse

COOLING TOWERS


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Nuclear power generation emits relatively low amounts of

carbon dioxide (CO2). The emission of green house gases and

their contribution to global warming is therefore relatively

little

This technology is readily available, it does not have to be

developed first

It is possible to generate a high amount of electrical energy

through a single plant

ADVANTAGES


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The problem of radioactive waste is still an unsolved one. It

is technically impossible to build a plant that is 100% secure

The feedstock for nuclear energy is Uranium. Uranium is ascarce resource. Its supply is estimated to last only for the

next 30 to 60 years depending on the actual demand

DISADVANTAGES


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