THERMAL POWER PLANT

Presentation By:-.

Basic Idea of Electricity Generation

• Coal is unloaded by electric traction system at Coal Yard• Coal is crushed to finer pieces of order 20 mm• Pulverization of Coal• Coal is send to furnace with the help of FD fan• Steam is generated at 540°C and 135 kg/sq.m• Steam is send to Super heater• Superheated steam is send to turbine• Production of Electricity by the generator

THREE MAJOR INPUTS TO POWER STATION:

COAL WATER FUEL OIL

FUNCTIONAL DESCRIPTION

Elements Of Thermal Power Station

DM PLANTDEAERATORBOILER FEED PUMPECONOMIZERAIR PRE-HEATERBOILER

SUPER HEATER

TURBINECONDENSER

COAL FEEDING SYSTEM

Coal is conveyed through rail wagon from out side of plant and through conveyor system collected in hopper and ground to a very fine powder by large metal spheres in the pulverised fuel mill.

Wagon Tippler

Conveyor

Coal Hopper

Pulverised Mill

COAL FEEDING SYSTEM

Air Pre-heater

Forced Draft Fan

Then it is mixed with preheated air driven by the forced draught fan. The hot air-fuel mixture is forced at high pressure into the

boiler.

BOILER

A boiler or steam generator is a device used to create steam by applying heat energy to water. Boiler is a device used for producing steam. There are two types of boilers:

a). Fire tube boilerb). Water tube boiler

Here, boiler used is of water tube type. In the boiler, heat energy transfer takes place through tube walls and drum. The gases lose their heat to water in the boiler or superheated. The escape heat is used to heat the water through economizer.ID and FD fans are used to produce artificial draught. The fuel oil is used to ignite the boiler and pulverized coal is lifted from the coal mills by PA fans.

BOILER FEED PUMP

May 1, 2023PMI Revision 00 9 18

ASH HANDLING SYSTEM

At the bottom of the furnace, there is a hopper for collection of bottom ash. This hopper is always filled with water to quench the ash and clinkers falling down from the furnace. Some arrangement is included to crush the clinkers and for conveying the crushed clinkers and bottom ash to a storage site.

It is very import to control the ash coming from the furnace.1. WET ASH HANDLING SYSTEM2. DRY ASH HANDLING SYSTEM

SUPER HEATER

Superheated steam is steam at a temperature higher than water's boiling point. If saturated stream is heated at constant pressure, it increases toward 100% Dry Saturated Steam. Continued heat input will then generate superheated steam. This will occur if saturated steam contacts a surface with a higher temperature. The steam is then described as superheated by the number of degrees it has been heated above saturation temperature

In a power plant, after the steam is conditioned by the drying equipment inside the steam drum, it is piped from the upper drum area into tubes inside an area of the furnace known as the super heater, which has an elaborate set up of tubing where the steam vapor picks up more energy from hot flue gases outside the tubing and its temperature is now superheated above the saturation temperature. The superheated steam is then piped through the main steam lines to the valves before the high pressure turbine.

STEAM TURBINE

The Steam Turbine is a prime mover that converts the stored mechanical energy in steam into rotational mechanical energy. A turbine pair consists of a ring of fixed blade and a ring of moving blades. The blades are so designed that the steam glides overt eh blade surface without striking it. As the steam floes over the covered surface of blade, it exerts a pressure on the blade along its whole length owing to its centrifugal force. The motive force on the blade will be the resultant of the centrifugal pressures on the blade length plus the effect of change of the steam as it flows over the blade.

Steam Turbine Theory:A turbine, being a form of engine, requires in order functioning a suitable working fluid, a

source of high-grade energy. When the fluid flows through the turbine, apart of the energy content is continuously extracted and converted into useful mechanical work. Steam and gas turbines use heat energy. While water turbines use pressure energy.

STRUCTURE OF TURBINE

Rotor Coupling and Bearings

The rotating elements consisting of three mono block rotors of HP, IP and LP turbines coupled together solidly by means of internally forged flanges thus in effect forming a single shaft system. The critical speed of the HP and IP rotors are designed to run above the normal rated speed. Each rotor is subjected to 20% over speed test. The Hp rotor is carried on tow bearings, a simple journal and thrust bearing at the other end directly adjacent to the coupling of the IP rotor. All the bearings are independently supported on separate bearing pedestals

ROTOR

CONDENSER

Condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it.

The steam after working in the turbine is condensed in condenser in each unit installed below the LP exhaust. The condenser is of surface type made of fabricated construction in single shell. The tube is of divided type double pass arrangement, having two independent cooling water inlet, outlet and reserve and water boxes. The condenser is provided with integral air-cooling zone at the centre from where air and non-condensable gases are continuously drawn out with the help of mechanical vacuum pump.

TYPES OF CONDENSER

Water Cooled Condenser

Air Cooled Condenser

COOLING TOWER

Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers either use the evaporation of water to remove process heat and cool the working fluid or in the case of closed circuit dry cooling towers rely solely on air to cool the working fluid.

It is a structure of height 110m designed to cool the water by natural draught. The cross sectional area is less at the center just to create low pressure so that the air can lift up due to natural draught and can carry heat from spherical drops. The upper portion is also diverging for increasing the efficiency of cooling tower. Hence it is named as natural draught cooling tower.

DE AREATOR

A Deaerator is a device that is widely used for the removal of air and other dissolved gases from the feed water to steam-generating boiler.

The condensed water is then passed by a feed pump through a deaerater.

ECONOMISER

Economizer are mechanical devices intended to reduce energy consumption, or to perform another useful function like preheating a fluid.Pre-warmed water first enter in a feed heater powered by steam drawn from the high pressure set, and then in the economiserEconomizer is a flue gas to water heat exchanger. Usually it is located below the LPSH in the boiler and above Air pre heater. Outside surface of the economizer tubes are heated by flue gases leaving the superheater and reheater which subsequently transfer heat to feed water flowing inside the tubes.Advantages of Economizer include1) 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 economizer and enter boiler tube at elevated temperature. The heat transfer area required for evaporation reduced considerably.

CHIMNEY

A chimney is a structure for venting hot gases or smoke from a boiler, furnace or fireplace to the outside atmosphere.

A chimney is a vertical structure for venting hot flue gases or smoke from a boiler to the outside atmosphere by means of the stack effect. The space inside a chimney is called aflue. The height of chimneys plays a role in their ability to transfer flue gases using stack effect. The dispersion of pollutants at higher altitude helps to ease down its influence on surroundings and reduces their concentrations in compliance with regulatory limits.The height of chimney is designed with respect to the boiler layout. The temp. is also maintained in the chimney. It is not more than 120 c. If it more than 120 c, then boiler will be corrupt..

ELECTROSTATIC PRECIPITATOR

Electrostatic Precipitator (ESP) is equipment, which utilizes an intense electric force to separate the suspended particle from the flue gases. In India coal is widely used to generate power. The exhaust gases from the furnace contains large amount of smoke and dust. If these gases are emitted directly into the atmosphere, it will cause great environmental problems. So it is necessary to extract this dust and smoke before emitting the exhaust gases into atmosphere. There are various methods of extracting dust but electrostatic precipitator is the most widely used. It involves electric changing of suspended particles, collection of charge particles and removal of charged particles from collecting electrodes.

ADVANTAGES OF ESP

Ability to cope with the corrosive atmosphere

It has high efficiency i.e. about 99%

It requires less maintenance

It offers low resistance to the flow of gases

Ability to treat large volume of gases at high temperature

SWITCHYARD

A Switch yard is a part of an electrical generation, transmission, system. Switchyard transform voltage from high to low,or the reverse, or perform any of several other important functions

CONTROL ROOM

A Control room is a room serving as a centre where a large physical facility or physically dispersed service can be monitored and controlled.

Instrumentation In Thermal Power Plant

• To measure and indicate the amount of deviation.INSTRUMENTS• To correct the deviation and bring back system to

normal.AUTOMATIC CONTROL

• To warn about the excessive deviations, if any.ANNUNCIATION• To isolate the equipments process from dangerous

operating conditions cause due to such excessive deviations.

PROTECTION

When the balance is disturbed, all the process variables deviate from their normal values thus creating the necessity for the following:-

ANY