main inplant traning report

7/31/2019 Main Inplant Traning Report

1/14

INDUSTRIAL VISIT

(AT 2X500 MW BHUSAVAL THERMAL POWER PLANT)

UNDER

VISIT BY: MAYUR BHAGWAN VANJARI

STUDENTS OF:TRIMURTI INSTITUTE OF TECHNOLOG JALGAON, MAHARASHTRA.


2/14

ABSTRACT

This report is based on our observations during our visit to the Bhusaval

Thermal Power Plant (2X500 MW). Nowadays various modifications havebeen done in the conventional method of generation in order to increase

the efficiency of the plant. So all the new and recent technologies have

been used in this plant and all such new machines and technologies were

observed and studied.


3/14

INTRODUCTION

In a thermal power plant, thermal energy generated after burning coal is

converted into the electrical energy. Steam generated in the boiler is

introduced into the turbine, which rotates the turbine blades at particular

speed and hence drives the generator to produce electricity. The main fuel

used for producing steam is coal. After we drive the generator on, the

magnetic flux is generated in the rotor winding, which is cut by the stator

winding and current is induced in the stator winding. This is the basic

principal of generation of the electricity but various factors have to be

taken into consideration for the efficient generation. Hence it includes

various systems and cycles such as turbine cycle, ash handling system, coalhandling system etc. so this report contains a study of all the systems and

all analysis are reported in brief.


4/14

UNIT OVERVIEW

For generating power, all the systems of the power plant need to work in

synchronised manner. In power plant, there are various systems which

work separately, but these are interconnected for generation purposes

which are as follows.

1. Boiler and ESP2. Turbine section3. Coal handling plant4. Ash handling plant5. Oil handling plant6. Other supporting systems such as

i.

Air conditioning systemii. Ventilation systemiii. EOT cranes, transformers etc.

There are in all 8 coal mills in this 1000 MW project out of which

6 mills are work for each of 500 MW unit. The mills are used for

crushing the coal into fine powders. This fine powdered coal is

taken to the furnace where it is burned. This heat energy so

produced is used to produce steam into the boiler, which is used

to drive the turbine blades and connected to the exciter to

generate the electricity. Three types of turbines are used namely

High Pressure Turbines (HPT), Intermediate Pressure Turbines

(IPT) and Low Pressure Turbines (LPT). The steam generated is

firstly passes to the HPT and the steam coming out is taken back

to the furnace and reheated and then given to the IPT. The

steam through the IPT is given directly to the LPT.

After the steam is used to drive the turbine blades, it needs to be

condensed. The steam is taken to the condenser for the

condensation. The resulting liquid is taken to the low pressure

heater (LPH) for heating. Then this is taken to the Deaerator,

where the air and the water are separated. Then the water is

taken to the High Pressure Heater for heating.


5/14

BOILER

The steam required to drive the turbine is generated in the

boiler. Water tube boiler is used in this power plant. The coal in

the powdered is taken from the mills. There are 8 mills, 4 on the

either side of the boiler. The coal is feeded from the 4 corners of

the boiler.

Initially some temperature is required to burn the coal. So firstly

the combustion in the boiler is carried out using LDO (Light Diesel

Oil). Then this heat is used in the combustion of HFO (Heavy

Furnace oil). Using this combustion process a sufficient heat

conditions are achieved for the burning of the coal.

The height of the boiler used in this plant is 80 meters. Many

number of water tubes are present around the furnace. The

combustion of the coal in the furnace generates sufficient heat

to convert steam into the water.

There are three steam lines through the boiler, a main steam line

and the other 2 through the HT turbine (for super heating

purpose).

At the 8 meter height, a ring header is present to supply water to

the boiler tubes.


6/14

ELECTROSTATIC PRECIPITOR

This part comes into picture for handling of ash coming out from

boiler section after combustion of coal. It is based on

electrostatic phenomenon. The ash coming out of furnace

contains many ions. Ionisation is done to extract this ash.

This portion consists of series of positively charged plates and

negatively charged coils placed alternately. Ash gets stick to the

plates. These plates are vibrated using hammers which are

coupled to the shaft of rapper motor.

As soon as the plates are hammered, due to vibration, ash

falls down and gets accumulate in hopper. Hopper looks like a

funnel which is provided with heater at its bottom to keep ash

temperature favourable (120 ). Air is also blown into the

hopper through pipes for easier flow of ash down to vacuum

container.

After that ash stored in buffer hopper and is transported to silo

through pipes. Pressurised air is used to make thetransportation. From silo sufficient amount of water is mixed

with the ash to form the slurry. This slurry is transported out of

the plant to the ash bund. This ash is further utilised for cement

and brick manufacturing.

On the other hand smoke and various gases are sent into air

through chimney. ID fan (induced draft) is used for thisoperation. Induced draft fan sucks the smoke and gases from the

hopper and sends them into air.

The chimney is structured with the height of 275m.


7/14

TURBINE CYCLE

There are three turbines present in this power plant namely High Pressure

Turbines (HPT), Low Pressure Turbines (LPT), Intermediate Pressure

Turbines (IPT). HPT is placed first followed by the IPT and LPT. The place

where all the turbines are place is called as the Turbine generator building.

To all these turbines a generator is connected to generate the electricity.

The turbines are placed at the 17 meter height. Between 0 meter and 17

meter all the machineries and equipments are placed required to

condense the generated steam.

The turbines are initially driven using the oil before the steam is passed

and the machineries required for this oil (mainly oil tank, pump etc.) are

kept at the 0 meter height. This oil is used to lubricate the shaft.

The steam is initially to the HTP. Then the heat coming through the HTP is

taken back to the furnace for reheating before it is given to the ITP. Then

this steam is given to the LTP directly. The resulting steam is taken back to

the condenser.

The steam required to drive the turbines should not be acidic for it does

not damage the turbine blades. The pH levels are checked whether the

steam is of the appropriate quality or not.


8/14

OIL HANDLING PLANT

In oil handling plant, oil handled are LDO (Light diesel oil) and HFO (high

furnace oil).

These oils are stored in cans of volume 2000 kl. There are two cans for

HFO and single for LDO. LDO has light viscosity and burns very easily, whileHFO is high viscous and takes time for combustion.

Pressure, transmission, temperature and withdrawing oil from containers

of train is controlled by control room.

LDO is costly as compared to HFO. Initially LDO is used for combustion.

The reason behind this is LDO burns easily. Then HFO is used and then

finally coal.


9/14

COAL HANDLING PLANT

Wagon tipplers are used to collect the coal from the wagon of

the train. Wagon tippler rotates the wagon 180 and coal is

collected in the container.

Then coal is transported to the bunker through the belt which

has an inclination of 15 and taken to the height of 60m of the

bunker.

There are crushers in between coal extraction point and bunkers.

The operation of crusher is to divide the carrier belt into two

ways one goes to unit 4 and another to unit 5.

Since during extraction of coal from wagons there forms huge

amount of dust, these dust is removed using air ducts provided

all over the carrier belt section.

When carrier reaches above the bunker a machine is used to

withdraw coal into different bunkers. Each bunker has capacity

of 800 tons.


10/14

PLANT CONTROL ROOM

All the major parameters of every section of plant are controlled from

Plant control room. PCR consists of two sections, one is operation and

other is control and instrumentation room.

PCR involves microprocessor based systems in which plant parameters are

controlled automatically or manually on computer by operator.

Using designed software, all essential controls are given on computer

screen.

It can be controlled by the operator operating particular section on

computer screen seating in operational room in PCR section.

For example, if there is increase in humidity in steam, it will be displayedon computer screen this is done using sensors.

To control the humidity temperature of air is increased all over from PCR.

Similarly, all operations can be controlled using PCR such as, working of

motor etc.

PCR is basically electronic system involving PLC and SCADA using

microprocessors and microcontrollers.


11/14

GENERATOR

Basic principle:

Generator is the synchronous machine which converts mechanical energy

into electrical energy by the principle of electromechanical energy

conversion. It consists of stator core, stator winding, rotor, rotor core and

yoke.

500 MW GENERATORS

Generator used in this power station is 500 mw capacity turbogenerator.

It is called turbogenerator because it is driven mechanically by steam

turbine.

Controlled dc excitation is given to rotor winding. Dc excitation iscontrolled by automatic voltage convertor. Brushless excitation system is

used which consist of pilot exciter, main exciter and rolling diode

arrangement.

An EMF is induced in the stator winding by action of flux cutting. This

induced EMF is nothing but three phase voltage across generator which is

21 KV in this case. Supply frequency is controlled by steam input to the

turbine.


12/14


13/14

SWITCH YARD

The switch yard of the power plant is for the transmission purpose of the

generated power. All the power is supplied to the switch yard in bulk

which then supplies it to the various sub stations. Basically a transmission

of 400 KV is to be stepped down for transmission and provided to the

consumers. 400 KV is supplied to some of the large consumers like big

industries, then some large consumers demand 220 KV or 132 KV supply

and 11 KV or 22KV is to be supplied at various levels. At the domestic

levels the generated voltage needs to be stepped down to 400 V. all this

lines of transmission pass through the switch yard.

At the stage of plant erection, ate auxiliaries need a supply. This

transmission of power to the plant from other stations is taken care by the

switch yard. The power from the other stations comes to the switch yard

through bus bars and is stepped down to 11 kV for the plant use by station

transformers.

The switch yard mainly consists of the transmission lines, isolators,

breakers, current transformers, potential transformers. Isolators are used

to de-energize the electrical circuits for the maintenance purpose. A

circuit breaker is an automatically operated switch designed to protect the

electrical circuit from damage due to overload and short circuit. CT and PT

are used basically for the measurement purposes.

When the power is generated, the plant auxiliaries are run on this

generated power. That means the plant uses its own power to run its

auxiliaries. Unit auxiliary transformer is used for this purpose. The unit

auxiliary transformer is a power transformer that provides power to the

station auxiliaries during normal operation. This transformer is connected

directly to the main generator and as such will provide the cheapest

power for the station use since any power from the transmission lines has

losses associated with it due to the line losses and transformer losses from

whatever step up transformer provided that power. These unit auxiliary

transformer is a three winding transformer having one primary winding

rated 22 kV and two secondary windings rated 6.6 kV and 4.2 kV. This

allows the transformer to power two different voltage level buses in the

plant .This transformers take the power generated in the plant, step itdown and supply it to the auxiliaries that need to run the power plant.


14/14

The UATs secondary windings are connected to the non -segregated

phase bus duct. This bus work conveys the power to the different medium

voltage switch gears located in the plant. Switch gear is the collective term

used all the equipment used for protection, measurement and controlling

electric power. In this plant design there are two sets of switch gear buses

rated at 6.6 kV and 4.2 kV. Each 6.6kV bus can be energised by the UAT.

The same is true for 4.2 kV switch gear.

main inplant traning report

Documents