Summer Training Presentation

Corporate Mentor:Pankaj VashisthaAssistant Manager

Summer Training carried out at

NTPC Ltd., ANTA

Presented by:Nishant Pareek(2013UME1791)

Department of Mechanical EngineeringMalaviya National Institute of Technology, Jaipur

CONTENTS

I. NTPC Ltd. Overviewa) Plant Information and Capacityb) ANTA GAS Power Station

II. Operation of a Combined Cycle Power Plant

III. Gas Turbine

IV. Steam Turbine

V. Waste Heat Recovery Boiler

NTPC Ltd. Overview

Plant information

• Established in 1975

• Became a Maharatna company in May 2010

• Ranked 400th in the 2016 ‘Forbes Global 2000’

• 44 NTPC stations -18 Coal based stations, 7 Gas based stations, 1 Hydro based station, 9 Joint Ventures, 9 Renewable Energy Projects

• Diversified Fields - Consultancy, Power Trading, Training Of Power Professionals, Rural Electrification, Ash Utilisation and Coal Mining

• Government of India’s holding - 75%

Growth in installed capacity: NTPC, NTPC Group & All India

Strategies of NTPC

ANTA Gas Power Station

• First combined cycle power plant set up by NTPC

• Installed capacity of 419.33 MW

• Installed in 1989

• Gas Source – GAIL HBJ Pipeline-south basin gas field

• Water Source – kota right main canal

• Unit sizes - 3X88.71MW GTG+1X153.2MW STG

• Good efficiency

• Cost of power from ANTA = Rs. 1.97 per unit

UNIT COMMISSIONED: -

• 1. Unit I - 88.71 MW capacity GTG-1 January1989

• 2. Unit II - 88.71 MW capacity GTG-2 March 1989

• 3. Unit III- 88.71 MW capacity GTG-3 May1989

• 4. Unit IV- 153.2 MW capacity STG March1990

ALLOCATION OF POWER TO STATES

STATES ALLOCATION IN MW PERCENTAGE

RAJASTHAN 83 19.81%

DELHI 44 10.5%

PUNJAB 49 11.69%

HARYANA 24 5.73%

HIMANCHAL 15 3.58%

J & K 29 6.92%

CHANDIGARH 05 1.19%

U.P 91.45 21.75%

UTTARANCHAL 15.88 3.79%

UNALLOCATED 63 15.04%

TOTAL 419.33 100%

SALIENT FEATURES OF NTPC ANTA

• 1. GAS TURBINE : 88.71MW, TYPE 13D-2, ABB MAKE, 5th STAGEREACTION TURBINE

• 2. GT COMPRESSOR : 18th STAGE AXIAL FLOW, RECTION BLADING

• 3. COMBUSTION CHAMBER : SINGLE SILO TYPE, DUAL FUEL FIREDBURNER

• 4. AIR INTAKE FILTER: SELF CLEANING, SYNTHATIC PAPER, TOTAL 945FILTERS IN THREE TIERS.

• 5. BYPASS STACK : VERTICAL 25M.HIGH.

• 6. WASTE HEAT RECOVERY BOILER : DUAL PRESSURE, DOUBLEDRUM,

UNFIRED, FORCED CIRCULATION.

• 7. STEAM TURBINE :153.20MW, TANDEM COMPOUNDED,

DOUBLE EXHAUST, CONDENSING TYPE,

SINGLE FLOW HORIZONTAL 25 STAGE HP

TURBINE.

• 8. CONDENSOR : DOUBLE PASS SURFACE CONDENSOR

WITH STAINLESS STEEL TUBES,

COOLING 13988M3.

• 9. GENERATOR : 3 PHASES, TWO POLE, AIR COOLED

COMBINED CYCLE POWER PLANT LAYOUT.

There are four main parts of CCPP :

Combine Cycle

Gas Turbine

Waste Heat Recovery Boiler

Steam Turbine

Overview of Combined Cycle

.

Gas turbine burns fuel.

• The gas turbine compresses air and mixes it with fuel that is heated to a very high temperature. The hot air-fuel mixture moves through the gas turbine blades, making them spin.

• The fast-spinning turbine drives a generator that converts a portion of the spinning energy into electricity

Heat recovery system captures exhaust.

• A Heat Recovery Steam Generator (HRSG) captures exhaust heat from the gas turbine that would otherwise escape through the exhaust stack.

• The HRSG creates steam from the gas turbine exhaust heat and delivers it to the steam turbine

Steam turbine delivers additional electricity.• The steam turbine sends its energy to the generator drive shaft,

where it is converted into additional electricity.

GAS TURBINE UNIT

• There are 3 Gas Turbine in NTPC ANTA each capacity of 88.71 MW

• TYPE 13D-2, ABB MAKE, 5th STAGE REACTION TURBINE

• Gas Turbine is a heat engine, working on the air standard Brayton cylcle.The gas turbine compresses air and mixes it with fuel that is heated to avery high temperature. The hot air-fuel mixture moves through the gasturbine blades, making them spin

• The process include :

1. Compressor

2. Combustion

3. Expansion

Working of gas Turbine• The compressor sucks in air from the atmosphere through the filters

called air intake filters.

• . The compressed air at approx. 10.4 bar passes into the combustion chamber

• The turbine and compressor are in common casing.

• The hot gases after combustion enter the gas turbine at about 10050C(at base load).

• The higher pressure and temperature gas pass through the turbine rotating it and generator, this produces the electrical power.

• The exhaust gas coming out of the GT is at about 5080C. This can be utilized to produce steam in WHRB

Gas Turbine Components

• Air intake system

• Compressor

• Combustion chamber

• Turbine

• generator

• Naphtha fuel system

Air intake system

• The air obtained from the environment contains numerous pollutants and unwanted compounds which may harm the machinery and reduce the efficiency of the system

• AIR INTAKE FILTER Specifications :

• SELF CLEANING, SYNTHATIC PAPER,

• There are three horizontal floors in filter house each floors carry 315 filters. TOTAL 945 FILTERS IN THREE TIERS.

• All filters are made of synthetic and cellulose fibres, using resign impregnated.

Compressor

Gas Turbine COMPRESSOR Specification:

• 18th STAGE AXIAL FLOW, RECTION BLADING

• 18 rotor and 19 fixed rows blades

• Material used: Blade material: tensile ferric chrome steel.

Compressor casing: graphite cast iron.

• The compressor casing has three circular ducts at 4th, 7th and 10th row of fixed blades.

• These ducts are closed to the outside by four bleed valves.

• . Bleed valves are kept open upto 2700 r.p.m so that certain amount of compressor air can be blown off.

Combustion chamber

• In combustion chamber, the air compressed and supplied by compressor is brought to the required process temperature by combustion of liquid/gas fuel.

• Specification: SINGLE SILO TYPE, DUAL FUEL FIRED BURNER

• Material used: Combustion chamber is welded steel plate fabricated.

Combustion chamber jacket,- low alloy ferrite steel

Turbine

• The gas turbine compresses air and mixes it with fuel that is heated to a very high temperature. The hot air-fuel mixture moves through the gas turbine blades, making them spin.

• Specifications: 88.71MW, TYPE 13D-2, ABB MAKE, 5th STAGE REACTION TURBINE

• turbine casing is made of heat resisting ferrite steel in order to with stand• Thermal stresses. The blade carrier for turbine fixed blades is made of ferrite steel

alloy casting.• Turbine blades are made ofcast nickel based alloy• Due to high temperature of incoming gases, the first and second row of rotor and

fixed blading are air cooled with air from compressor discharge.

Cooling of turbine blades

• The cooling air is fed to the first & second row of fixed blades through holes drilled in the blade carrier and to the first & second row of rotor blades through hole drilled in shaft,

• cooling air passes along several holes made in blades and finally blowing out through numbers of slits in the trailing/leading edge of the blade.

• This method of cooling ensures that blades are thoroughly cooled, thereby avoiding cracks induced by thermal stresses.

Generator

Specifications : 3 PHASES, TWO POLE, AIR COOLED

• The generator and turbine are placed on common and plain concrete foundation, with same centre line level for the turbine and generator rotor.

• The mechanical energy generated by turbine is converted to electrical energy by the generator and appear in the stator winding in the form of current and voltage.

• It lead the magnetic flux, and carries the field winding, the generator is self excited. The power required for the excitation is taken from the generator term finals and fed to the field winding through the excitation transformer and the thyristor-controlled rectifier units.

Naphtha fuel system

• Naphtha comes from naphtha station via the forwarding pumps at around 15bar.

• Naphtha then passes through duplex filter to the main fuel oil pump, which raises the press to approx. 80 bar. There is release valve which opens when firing speed is reached (600rpm).

WASTE HEAT RECOVERY BOILER

• Wagner-biro supplied boilers for anta combined cycle power plant known as waste heat recovery boilers (WHRB), which are of non fired, dual pressure, forced circulation type

• The boiler has two different water/steam cycles known as high pressure system and low pressure system. Each system has its own boiler drum and circulating pumps, and is feed by HP & LP feed water pumps from a common feed water tank.

• The pressure and temperature of high pressure super heated steam is 64 bar and 4900C and that of LP 6 bar and2060C.

VARIOUS ACCESSORIES USED IN (WHRB) ARE:

• 1.SUPERHEATER- Super heater is used to raise the temperature of steam above the saturation temperature by absorbing the heat from flue gases

• 2. EVAPORATOR- An evaporator is the component of a refrigeration system and is used to extract heat from the chamber is to be kept at low temperature

3. ECONOMIZER- The function of an economizer in a steam generating unit is to absorb heat from the flue gases and add this as sensible heat to the feed water

4. AIR PREHEATER- An air preheater is used to recover heat from flue gases. It is installed between the chimney and economiser

5. DEAERATOR- It is used to remove air from water as air carries oxygen which is corrosive in nature so to protect the various parts of boiler from corrosion.

6. DESUPERHEATOR- It is used keep the temp. Of superheated steam constant

WASTE HEAT RECOVERY BOILER

WHRB Working………

Maintenance of boiler• Cleanliness

• Proper air circulation

• Use boiler operating log sheets & maintenance records

• Ensure personnel properly trained

• Before start-up, ensure that the boiler is free of all potentially dangerous situations

• Clear intakes and exhaust vents; check for deterioration and possible leaks

• Ensure a thorough inspection by a properly qualified inspector

• Establish a checklist for proper start up and shutdown of boilers

• Maintenance of boiler on frequent basis depending on the component part

STEAM TURBINE UNIT

• Function of Steam turbine - Extracts thermal energy from pressurized steam and converts it into rotary motion.

• Turbine classification:

i. Impulse Turbine

ii. Reaction Turbine

• Stationary blades - Potential energy of the steam Kinetic energy and direct the flow onto the rotating blades

• Rotating blades - Kinetic energy Forces, caused by pressure drop, which results in the rotation of the turbine shaft

There is one steam turbine in NTPC ANTA of capacity 153.2MW

Components of steam turbine

1. Turbine shaft

2. Turbine casing

3. Moving blades fixed on rotor

4. Fixed blades fixed on casing

5. Turbine bearings and couplings

6. Stop and Control Valves

7. Barring Gear

The Main Turbine (Tandem 3 cylinder turbine)

HP Turbine – 25 stages

LP Turbine – 2*6 stages

• H.P and L.P. turbine rotor - Rigidly compounded

• L.P. and H.P rotor - Lens type semi flexible coupling

STEAM TURBINE SPECIFICATION

• MAKE : ABB , GERMANY

• RATED OUTPUT : 153.28 MW

• MAX. TERMINAL OUTPUT : 173.18 MW

• LIVE STEAM PRESSURE

• HP : 62.7 bar (abs.)

• LP : 5.5 bar (abs.)

• LIVE STEAM TEMPERATURE

• HP : 485 0C

• LP : 207 0C

• VACUUM : 0.1 bar(abs.)

• SPEED : 3000 RPM

• NO. OF STAGES : 25

• TOTAL HP STEAM FLOW : 459 t/hr.

• HP MS PRESSURE : 61.75 bar

• HP MS TEMPERATURE : 485 0C

• HPT EXH. PRESSURE : 4.27 bar

• HPT EXH. TEMPERATURE : 181.8 0C

HP TURBINE

LP TURBINENO. OF STAGES : 2X6,double flow TOTAL LP STEAM FLOW : 117.3 t/hr.LP MS PRESSURE : 4.5 barLP MS TEMPERATURE : 207 0CLPT EXH. TEMPERATURE : 45.9 0C

Maintenance of steam turbine

Part Affected Wear out problem Comments, suitable condition

monitoring

Blading Erosion by solid particles Usually occurs gradually, worst at inlet

blading. Performance analysis detects.

Blading Parts breaking off Usually sudden. Vibration analysis

detects. (ANSYS Software)

Bearings Scoring damage to white metal Performance analysis, vibration analysis,

wear particles in oil

Rotors Rubbing, temporary unbalance, cracking,

misalignment

Vibration analysis, and off-line, some

NDT

Steam valve strainers, valves

spindles

Deposits Likely to occur gradually, mostly in areas

around 260°C. Performance analysis

detects.

Generator rotor, stator Insulation faults Electrical plant testing several

techniques

Condenser Air in leakage Tube fouling Performance analysis

Feedwater heaters Air in leakage, tube fouling by scale or oil Performance analysis

Valves- HP, IP bypass Leakage Performance analysis. Acoustic leakage

detection is also possible

References

I. NTPC Limited (n.d.). Company History. Retrieved from http://www.ntpc.co.in/en/about-us/history

II. NTPC Limited (n.d.). Growth of NTPC. Retrieved from http://www.ntpc.co.in/en/about-us/ntpc-overview

III. Bolaji and Emeka, R. 2014. Operation and Maintenance Schedule of a Steam Turbine Plant in Lappeenranta, Masters Thesis, Saimaa University of Applied Sciences. 99p

IV. http://www.instrumentationengineers.org/2013/06/working-principle-of-impulse-turbines.html

V. http://energy.gov/fe/how-gas-turbine-power-plants-workVI. http://www.ntpc.co.in/en/services-and-

initiatives/consultancy/services/operation-and-maintenance-o-and-m