Detailed Internship Report about RAJIV GANDHI COMBINED CYCLE POWER PLANT-NTPC LTD. Includes information about Thermodynamic Cycles, Combined Cycle, HRSG (Heat Recovery Steam Generator), and various components of a Combined Cycle Power Plant.

1. INTERNSHIP REPORT
RAJIV GANDHI COMBINED
CYCLE POWER PLANT-NTPC
LTD.
Guided by
Mr. M.S DINESH KURUP
Sr.MANAGER (MTP)
RGCCPP-KAYAMKULAM
By
SREESANKAR.J
M.E THERMAL ENGINEERING
S.N.S COLLEGE OF TECHNOLOGY
COIMBATORE-35

2. ABOUT NTPC LIMITED
 NTPC Limited (formerly known as National Thermal Power
Corporation Limited) is a Central Public Sector Undertaking
(CPSU) under the Ministry of Power, Government of India,
engaged in the business of generation of electricity and allied
activities. It is a company incorporated under the Companies Act
1956 and a "Government Company" within the meaning of the
act.
 The headquarters of the company is situated at New Delhi.
NTPC's core business is generation and sale of electricity to
state-owned power distribution companies and State Electricity
Boards in India. The company also undertakes consultancy and
turnkey project contracts that comprise of engineering, project
management, construction management and operation and
management of power plants. The company has also ventured
into oil and gas exploration and coal mining activities.
 It is the largest power company in India with an electric power
generating capacity of 42,964 MW. Although the company has
approx. 18% of the total national capacity it contributes to over
27% of total power generation due to its focus on operating its
power plants at higher efficiency levels (approx. 83% against the
national PLF rate of 78%).
 It was founded by Government of India in 1975, which held 75%
of its equity shares on 31 March 2013 (after divestment of its
stake in 2004, 2010 and 2013).
In May 2010, NTPC was conferred MAHARATANA status by the
Union Government of India. It is listed in Forbes Global 2000 for
2014 at 424th rank in the world.

3. ABOUT RAJIV GANDHI COMBINED CYCLE
POWERPLANT, KAYAMKULAM
 The Rajiv Gandhi Combined Cycle Power Plant (also known
as Rajiv Gandhi CCPP Kayamkulam or NTPC Kayamkulam) is
a combined cycle power plant located at Choolatheruvu
in Alappuzha district, Kerala, India.
 The power plant is owned by NTPC Limited. The power plant is
fueled by imported and indigenous naphtha. Source of the cooling
water is Achankovil River. Total installed capacity of the plant is
350MW.
 The plant is a combined cycle power plant comprising of two Gas
Turbines and one Steam Turbine of capacities 115MW (2), and
120MW respectively. Unite 1 was commissioned on 1998
November, Unite 1 on February 1999 & Unite 3 on October 1999.
 HSD (High Speed Diesel), Naphtha are used as fuels.

4. THERMODYNAMIC CYCLES
 CARNOT CYCLE
 RANKINE CYCLE
 BRAYTON CYCLE
A. CARNOT CYCLE
 The Carnot cycle is a theoretical thermodynamic
cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and
expanded by others in the 1830s and 1840s.
 It can be shown that it is the most efficient cycle for converting
a given amount of thermal energy into work, or conversely,
creating a temperature difference (e.g. refrigeration) by doing
a given amount of work.
 Every single thermodynamic system exists in a particular
state. When a system is taken through a series of different
states and finally returned to its initial state, a thermodynamic
cycle is said to have occurred. In the process of going through
this cycle, the system may perform work on its surroundings,
thereby acting as a heat engine.
 A system undergoing a Carnot cycle is called a Carnot heat
engine, although such a "perfect" engine is only a theoretical
limit and cannot be built in practice.

5. B. RANKINE CYCLE
 The Rankine cycle is a model that is used to predict the
performance of steam engines. The Rankine cycle is an
idealized thermodynamic cycle of a heat engine that converts heat
into mechanical work. The heat is supplied externally to a closed
loop, which usually uses water as the working fluid. The Rankine
cycle, in the form of steam engines, generates about 90% of all
electric power used throughout the world, including virtually
all biomass, coal, solar thermal and nuclear power plants. It is
named after William John Macquorn Rankine, a
Scottish polymath and Glasgow University professor.

6. C. BRAYTON CYCLE
 The Brayton cycle is a thermodynamic cycle that describes the
workings of a constant pressure heat engine. Gas
turbine engines and air breathing jet engines use the Brayton
Cycle. Although the Brayton cycle is usually run as anopen
system (and indeed must be run as such if internal combustion is
used), it is conventionally assumed for the purposes
of thermodynamic analysis that the exhaust gases are reused in
the intake, enabling analysis as a closed system.
 The engine cycle is named after George Brayton (1830–1892),
the American engineer who developed it, although it was
originally proposed and patented by Englishman John Barber in
1791.[1] It is also sometimes known as the Joule cycle.
The Ericsson cycle is similar to the Brayton cycle but uses
external heat and incorporates the use of a regenerator. There
are two types of Brayton cycles, open to the atmosphere and
using internal combustion chamber or closed and using a heat
exchanger.

7. COMBINED CYCLE
 In electric power generation a combined cycle is an assembly
of heat engines that work in tandem from the same source of heat,
converting it into mechanical energy, which in turn usually
drives electrical generators.
 The principle is that after completing its cycle (in the first engine),
the working fluid of the first heat engine is still low enough in its
entropy that a second subsequent heat engine may extract energy
from the waste heat (energy) of the working fluid of the first engine.
 By combining these multiple streams of work upon a single
mechanical shaft turning an electric generator, the overall net
efficiency of the system may be increased by 50 – 60 percent.
 That is, from an overall efficiency of say 34% (in a single cycle) to
possibly an overall efficiency of 51% (in a mechanical combination
of two (2) cycles) in net Carnot thermodynamic efficiency. This can
be done because heat engines are only able to use a portion of the
energy their fuel generates (usually less than 50%). In an ordinary
(non combined cycle) heat engine the remaining heat (e.g., hot
exhaust fumes) from combustion is generally wasted.
 Combining two or more thermodynamic cycles results in improved
overall efficiency, reducing fuel costs. In stationary power plants, a
widely used combination is a gas turbine (operating by the Brayton
cycle) burning natural gas or synthesis gas from coal, whose hot
exhaust powers a steam power plant (operating by the Rankine
cycle).
 This is called a Combined Cycle Gas Turbine (CCGT) plant, and
can achieve a thermal efficiency of around 60%, in contrast to a
single cycle steam power plant which is limited to efficiencies of
around 35-42%. Many new gas power plants in North America and
Europe are of this type. Such an arrangement is also used for
marine propulsion, and is called a combined gas and
steam (COGAS) plant. Multiple stage turbine or steam cycles are
also common.

8.  Combined Cycle consists of
A. Topping cycle
B. Bottoming cycle

9. DIFFERENT SYSTEMS IN THE PLANT
o Condensate System
o Feed Water System
 High Pressure Feed Water System
 Low Pressure Feed Water System
o Condensate Recirculation System
o Cooling water System
o Cooling Tower System
o Steam Circuit
 High Pressure Circuit
 Low Pressure Circuit
o Fuel Oil System
 HSD (High Speed Diesel)
 Naphtha
o Seal Steam System
o Turbine Oil System (Steam Turbine/Lub Oil
System)

10.  CONDENSATE SYSTEM
• The steam after condensing in the condenser known as
condensate, is extracted out of the condenser hot well by
condensate pump and taken to the deaerator through ejectors,
gland steam cooler and series of LP heaters
• Condensate Extraction Pump : To pump out the condensate to D/A
through ejectors, GSC and LPH
• Gland Steam Condenser: To increase the temperature of
condensate.
 Condensate polishing unit: To remove cat-ion and an-ion from the
condensate.
 FEED WATER SYSTEM
 Feed water system serves three purposes in the power plant.
 They provide efficiency gains in the steam cycle by increasing the
initial water temperature to the boiler, so there is less sensible heat
addition which must occur in the boiler,
 They provide efficiency gains by reducing the heat rejected in the
condenser, and they reduce thermal effect in the boiler.
 Steam is extracted from selected stages in the turbine to shell and
tube heat exchangers or to open feed water heaters where the
steam and feed water are in direct contact.
 HP FEED WATER SYSTEM
 Located downstream of boiler feed pump. Typically, the tube
side design pressure is at least 100 KG/CM2, and the steam
source is high pressure turbine.

11.  LP FEED WATER SYSTEM
 Located (with regard to the feed water flow) between
condensate pump and either boiler feed pump. It normally
extracts steam from the low pressure turbine.
 CONDENSATE RECIRCULATION SYSTEM
o Condensate Pumps
o The function of these pumps is to pumps out the
condensate to the deaerator thru' ejectors, gland
steam cooler, and L.P. heaters. These pumps have
FIVE stages and since the suction is at a negative
pressure, special arrangements have been made
for providing sealing.
o The pressure build up in 5 stages as suction is at
negative pressure.
o Recirculation
o It is done when the de aerator level controller trips
in order to prevent cavitations.
o Boiler Feed Pump
o To give the required pressure to the feed water
before entering into boiler
o Horizontal barrel type multi stage pump.

12.  COOLING WATER SYSTEM
 Cooling water system is the system that handles various cooling
needs of the power plant.
 Cooling water is used in condenser to remove heat from the
steam.
 The cooled water from the condenser is send to the Cooling
tower system for further cooing purpose.
 Cooling water system for turbine designed to accommodate the
heat dissipation requirement of the turbine and the generator
lubrication system, generator cooling system.
 CW system is a closed loop system which gets CW from cooling
water module. It pumps CW to GT and generators which
receives heat from GT and generators components.
 DMCWS [DEMINERALISED COOLING WATER
SYSTEM]
 DMCWS supplies cooling water to equipment when ever its
necessary.
 DMCWS supplies CW to HPBFP (High Pressure Boiler Feed
Pump), LPBFP (Low Pressure Boiler Feed Pump), CPHRCP
etc.
 DMCWS consists of a closed loop circuit that consists of a
DMCWS over head tank which is an expansion tank (Constant
level of water is maintained always)
 Two plate type heat exchangers, and ACWS (Auxiliary Cooling
Water System) which is used to cool down the water coming
from DMCWS.
 ACWS gets the cold water from the CW sump.

13.  COOLING TOWER SYSTEM
 Remove heat from the water discharged from the condenser so
that the water can be discharged to the river or re circulated and
reused.
 Air can be circulated in the cooling towers through natural draft
and mechanical draft.
 At RGCCPP there are induced draft type cooling towers.
 STEAM CIRCUIT
 High Pressure Circuit
 Low pressure Circuit
 Steam circuit is the circuit that involves all steam handling in the
plant.
 The hot exhaust from the gas turbine is passed to the HRSG with
a temperature of 521oC, 50.45 KG, 166.65T/Hr.
 HIGH PRESSURE CIRCUIT
 High pressure circuit handles the high temperature high
pressure process that leads to the HPT (High Pressure
Turbine) in the steam cycle.
 The circuit includes HP Drum, HPBP (High Pressure Boiler
Pump), HP Turbine.
 LOW PRESSURE CIRCUIT
 Low pressure circuit handles the low temperature high
pressure process that leads to the LPT (Low Pressure
Turbine) in the steam cycle.
 The circuit includes LP Drum, LPBP (Low Pressure Boiler
Pump), LP Turbine.

14.  GAS TURBINE
 Gas turbine model series: MS 9001
 Shaft Relation: Counter Close Wise
 Turbine Shaft Speed: 3000RPM
 Control: SPEEDTRONIC MARK V Solid state electronic
control system.
 Air In: 28oC
 Fuel: Natural Gas, Naphtha, HSD.
 Power turbine Stages: 3
o Functional Description
The MS9001 is a Simple cycle, single-shaft gas turbine with
14 combustion, reverse flow combustion system. The
Ms9001 gas turbine assembly consists of 6 major sections:
 Air Inlet
 Compressor
 Combustion System
 Turbine
 Exhaust
 Support System
o Compressor Section
 Rotor
 Stator
 Inlet casing
 Forward compressor casing
 After compressor casing
 Compression Discharge Casing
o Combustion System
 Combustion Wrapper

15.  Combustion Chambers(no.14)
 Spark Plugs
 Ultraviolet flame Detectors
 Fuel Nozzle
 Cross Fire Tubes
o Turbine Section
 Turbine Rotor
 Turbine Casing Exhaust Frame
 Exhaust Diffusers
 Nozzle
 GAS TURBINE FLAME DETECTION SYSTEM
 The Honeywell flame mounting system describes are
designed to detect the ultraviolet radiations emitted by a
hydrocarbon flame and provide either a logic signal
[System YG 150Aol] a relay contact closure to indicate
flame in a gas turbine.
 AUXILIARY UNITE FOR A GAS TURBINE
 The auxiliary unite of this type are specially designed for
compact turbo alienate unites with:
 To drive the “Turbo axillaries” at appropriate speed.
 To drive the turbine through its starting device in the
starting process.
 They are equipped with integral oil pumps
 The gear is of single helical type.
 Casing
 Gearing
 Lub oil pumps
 STARTING SYSTEM
 Timing power is supplied by the starting system during gas
turbine starting and stopping.

16.  ELECTRIC STARTING MOTOR
 The prime motor is a 4 pole, 6600VAC, 50Hz, 1750HP motor.
The motor operates in the single speed to produce the
necessary horse power to start of the gas turbine.
 LUBRICATION OIL SYSTEM
 Lubrication of the gas turbine and generator is fulfilled by a
common force-feed lubrication system
 System consists of:
 Tank
 Pumps
 Coolers
 Protection devices
 Hydrocarbon based lubrication oil (recommended for the gas
turbine)
 FUEL SPECIFICATION OF BHEL/GE
 Firing temperature: 1600oF [870oC] or Higher
 Fuel Used: HSD (High Speed Diesel)
 Naphtha: A highly volatile fuel with a boiling range
between gasoline and light distillate. The low flas
point and high volatility require special safety
considering its very low viscosity may result in poor
lubricity.
 HSD is used in the starting stage of the turbine and when it
reaches 2000 RPM the fuel switches to Naphtha.
 PURGING AIR SYSTEM
 Purging is the process of removing unburned fuel and air before
the turbine starts.
 In the starting stage of the GT there is a 15 second purging
stage that is been automatically performed by the control
system.

17.  In the stage some amount of HSD is supplied in to the
combustion chamber and burned and is purged out.
 HYDRAULIC SUPPLY SYSTEM
 Hydraulic fluid of a high pressure is provided by the hydraulic
supply system to operate control of the GT.
 High Pressure Hydraulic oil controlling the GT start/stop and
control valve assembly fuel oil by pass valve assembly and
variable Inlet Guide vanes (IGV) mechanism.
 Major system compounds include:
 Main hydraulic supply pump
 Auxiliary supply pump
 System filter
 Transfer valves
 The accumulator manifold assembly
 TRIP OIL SYSTEM
 It is the primary protection interface between the gas turbine
control panel and the component as the turbine which shut off.
 SEAL STEAM SYSTEM
 Seal steam system is a system that seals the HPT & LPT
preventing the turbine from leaking the steam during work
done.
 The shaft and turbine consists of a annular grooves that
reduce the pressure so as to prevent the wastage.
 LPT sealing system will prevent air coming in, as the pressure
inside the turbine is low as compared to atmosphere.
 The steam collected from leak steam is used for GSC (Gland
Steam Condenser)
 FIRE PROTECTION SYSTEM
 The CO2 fire protection system for the gas turbine unites
extinguishing the fire by reducing the oxygen.

18.  To reduce the oxygen content, a quantity of Co2 greater than
34% a compared by volume is discharged in to the combustion
chamber, when exposed to high temperature.
 OVER SPEED PROTECTION SYSTEM
 Under normal operation the speed of the shaft is under the
control of speed loop or temperature loop.
 The over speed protection system consists of a primary
electronic system.
 The primary electronic over speed protection system senses
the turbine speed, speed detection software and associated
circuits.
 Mechanical over speed protection system is a backup for
electronic over speed protection system failure.
 OVER TEMPERATURE PROTECTION SYSTEM
 The over temperature protection system protects the GT from
possible damage caused by over firing. It is a backup system
which operates only after failure of the speed and temperature
over ride loops.
 Control of turbine is done mainly by start up speed acceleration,
synchronization and temperature controls
 Temperature, speed, vibration, flame and compressor operation
limits over temperature and over speed systems are provided
as independent backup system for temperature control and
speed control systems.
 Vibration detections and protection is activated by abnormal
turning vibration amplitude.
 Flame Diction and protection system is activated if flame is not
established during start up or if it is lost during operation.

19.  WORKING OF THE PLANT
 Combined cycle power generation combines 2 cycles for
operation, namely the gas turbine cycle and the vapor power
(or steam turbine) cycle.
 In a gas turbine power plant, the turbine starts with HSD (High
Speed Diesel) and when it reaches 2000 RPM the fuel
switches to Naphtha and compressed air undergo
combustion.
 The resultant high pressure gas drives the gas turbine which
in turn produces electricity.
 Although it is clean and fast in starting up, the gas turbine
power plant suffers from low thermo efficiency of about 25 to
30%.
 Much of the energy is wasted in the form of gas turbine
exhaust.
 The combined cycle power generation makes use of the
merits of the high temperature (1100 to 1650°C) gas turbine
cycle and the lower temperature (540 to 650°C) steam turbine
cycle.
 The hot exhaust gas from the gas turbine, instead of being
released as waste, is captured and channeled to the steam
turbine where steam is heated by the exhaust to drive the
turbine.
 A combined cycle power plant consists of two main parts: the
gas turbine plant and the steam turbine plant.
 In the gas turbine plant, atmospheric air enters through the
compressor and into the combustor (or combustion chamber)
where fuel (usually natural gas) is added.
 Combustion takes place and the hot gas drives the turbine,
which in turn drives the generator and produces electricity.
 The hot flue gas from the gas turbine enters a heat
exchanger, sometimes known as Heat Recovery Boiler or
Heat Recovery Steam Generator [HRSG], where it is used to
heat up the steam.

20.  The superheated steam is then used to drive the steam
turbine which in turn drives the generator to produce
electricity.
 The exit steam from the steam turbine goes through a
condenser and then back to the heat exchanger where the
cycle repeats itself.
 ELECTRICAL SYSTEM
 The power production in RGCCPP-Kayamkulam by two
115MW Gas Turbines and one 120MW Steam Turbine unite
is supplied to the customers through two buses of 220KV.
 Power evacuation lines are to 4 places:
 Edappon
 Kundara
 Pallom 1
 Pallom 2
 Produced current 115MW current is stepped up to 220KV by
using a step up transformer and is uploaded to the 220KV
Bus.
 A Unite Auxiliary Transmission (UAT) line of 1.66KV bus is
also available for the plant use.
 A Bus coupler is used to separate the two lines of GTPP. This
keeps two plants isolated.
 The plant also consists of a Black Start Diesel Generator
(BSDG). In case of any plant black out.
 BACK CHARGING
 Back charging is the process of taking required amount of
power back from the main power line when the plant is not
running.