Power Plant Design with Renewable Energy
MEEN 30305
GAS TURBINE POWER PLANT
Technical Report
BSME 4-2
Bobis, Joshua Emmanuel
Gavino, Raphael Racso
Lazaro, Jose IV
Manabat, Brian Victor
Palma, Samantha Joi
Rafer, Ian Gabriel
Saguid, Aileen
Valino, Russell Simon
TABLE OF CONTENTS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
BASIC CONCEPTS………………………………………………………………………....…..4
OVERVIEW……………………………………………………………………………………....5
WORKING PRINCIPLE…………………………………………………………………………7
DEVELOPMENTS………………………………………………………………….……………8
4.1
1903
4.2
1903, AEGIDUS ELLING OF NORWAY
4.3
1905, HANS HOLZWARTH OF GERMANY
4.4
FOR LOCOMOTIVE PROPULSION
4.5
FOR AUTOMOTIVE PROPULSION
4.6
FOR MARINE PROPULSION
TYPES OF GAS TURBINE POWER PLANT………………………………………………..10
5.1.
TYPES OF GAS TURBINE POWER PLANT BY SYSTEM
5.2.
TYPES OF GAS TURBINE POWER PLANT BY TURBINE
5.3.
TYPES OF GAS TURBINE POWER PLANT BY COMPRESSOR
5.4.
TYPES OF GAS TURBINE POWER PLANT BY USE
AREA/AVAILABILITY OF GAS TURBINE POWER PLANT……………………………….15
FACTORS AFFECTING GAS TURBINE PERFORMANCE……………………………….17
7.1.
AIR TEMPERATURE AND SITE ELEVATION
7.2.
HUMIDITY
7.3.
INLET AND EXHAUST LOSSES
7.4.
FUELS
7.5.
FUEL HEATING
7.6.
AIR EXTRACTION
7.7.
INLET COOLING
PHILIPPINE CONTEXT OF GAS TURBINE………………………………………………...21
8.1.
POWER PLANTS FED BY THE MALAMPAYA GAS FIELD
8.2.
NATURAL GAS RESERVES
8.3.
NATURAL GAS CONSUMPTION
GLOBAL CONTEXT OF GAS TURBINE…………………………………………………….24
ADVANTAGES OF NATURAL
GAS……………………………………………...…………..26
DISADVANTAGES OF NATURAL
GAS……………………………………………………...27
LEVELIZED COST OF
ENERGY……………………………………………………………..28
ENVIRONMENTAL
IMPACTS………………………………………………………………...30
13.1.
LAND USE
13.2.
WATER QUALITY
13.3.
AIR EMISSIONS
13.4.
LIFE CYCLE GLOBAL WARMING EMISSIONS
13.5.
LIFE CYCLE ASSESSMENT
14.
15.
16.
17.
18.
19.
20.
21.
FUTURE OF GAS TURBINES………………………………………………………………..36
13.1. CARBON CAPTURE AND STORAGE
13.2. HYDROGEN AS FUEL
PERFORMANCE AND DESIGN OF GAS TURBINES…………………………………….40
15.1.
COMPRESSOR
15.1.1.
CENTRIFUGAL COMPRESSOR
15.1.1.1.
ADVANTAGES
15.1.1.2.
DISADVANTAGES
15.1.2.
AXIAL FLOW COMPRESSOR
15.1.2.1.
ADVANTAGES
15.1.2.2.
DISADVANTAGES
15.1.3.
THERMODYNAMIC PROCESSES
15.2.
COMBUSTION
15.3.
TURBINE
EQUIPMENT SELECTION
BRAYTON CYCLE……………………………………………………………………………..73
FORMULAS…………………………………………………………………………………….74
SAMPLE EQUIPMENT DIMENSIONS………………………………………………………75
19.1.
4.5 MW Gas Turbine
19.2.
52 MW Gas Turbine
PROBLEM SOLVING………………………………………………………………………….77
REFERENCES………………………………………………………..……………………….86
BASIC CONCEPTS
The use of gas turbines for generating electricity dates back to 1939. Today, gas turbines
are one of the most widely used power generating technologies.
Gas turbines are a type of internal combustion (IC) engine in which burning of an air-fuel
mixture produces hot gasses that spin a turbine to produce power. It is the production of hot gas
during fuel combustion, not the fuel itself that gives gas turbines the name.
The gas turbine has become an important, widespread, and reliable device in the field of
power generation, transportation and other applications. Gas turbine power plant has uses in
high-speed, massive compressor vehicles. Additionally, they provide electricity for aircraft and
ships.
The gas turbines being installed in many of today's natural-gas-fueled power plants are
complex machines, but they basically involve three main sections:
Figure 1. Gas Turbine
The compressor, which draws air into the engine, pressurizes it, and feeds it to the combustion
chamber at speeds of hundreds of miles per hour.
The combustion system, typically made up of a ring of fuel injectors that inject a steady stream
of fuel into combustion chambers where it mixes with the air. The mixture is burned at
temperatures of more than 2000 degrees F. The combustion produces a high temperature, high
pressure gas stream that enters and expands through the turbine section.
The turbine is an intricate array of alternate stationary and rotating aerofoil-section blades. As
hot combustion gas expands through the turbine, it spins the rotating blades. The rotating blades
perform a dual function: they drive the compressor to draw more pressurized air into the
combustion section, and they spin a generator to produce electricity.
OVERVIEW
How does a gas turbine work?
In a Gas Turbine Power Plant, there’s a Generator which is an electrical machine. To generate
electricity, this generator needs a Prime Mover which is a Gas Turbine.
Figure 2. Generator and Gas Turbine
Gas Turbine transforms the chemical energy in the fuel., for example, natural gas or the
similar fuel into mechanical energy.
The mechanical energy generated by the Turbine exit shaft is then transferred through a
gearbox to the Generator’s shaft.
Now the generator can create electrical energy.
Figure 2.1. Conversion of Mechanical Energy to Chemical Energy
This primitive form of electrical energy normally has a low or medium level of voltage and
to better manage the power loss in transmission lines, this voltage should be increased by stepup transformers.
Such transformers give an adequate level of voltage to the electrical energy to be
transmitted through the transmission lines and delivered to the grid.
Figure 2.2. Process of transmitting energy
WORKING PRINCIPLE
Based on the Brayton cycle, the gas turbine power plant operates. The air-fuel mixture is
compressed during this cycle, burned, and then expelled after passing through a gas turbine. A
gas turbine uses air as its working medium throughout its functioning.
Figure 3. Parts of Gas Turbine
The following are the stages of a gas turbine’s operation:
Suction procedure:
In the beginning, the turbine draws air from the atmosphere into the compression chamber and
transfers it to the compressor.
Compression Procedure:
The compressor compresses the air as it enters, transforming the kinetic energy of the air into
pressure energy. It then transforms the air into high-pressure air.
The Combustion Process:
The compressed air enters the combustion chamber following the compression process. An
injector places fuel inside the combustion chamber, which combines with the air. The combustion
chamber ignites the air-fuel mixture after mixing. The ignition process transforms the air-fuel
mixture into high-pressure, high-temperature gases.
The Turbine Section:
Some of the gas’s energy converts into mechanical energy when it reaches the turbine portion,
while some of its energy expends. The turbine blades rotate as the combustion gas expands
through it. The rotating blades serve two purposes. They drive a gas generator attached to the
turbine and operate a compressor to bring in more air for operation.
Creating electricity process:
The gas turbine power plant’ shaft has a generator attached to it. The turbine delivers mechanical
energy to the generator, transforming it into electrical power. Exhaust gasses include waste
energy that escapes. The exhaust gas could be used for external purposes, such as immediately
producing thrust in a turbojet engine or turning a second power turbine that could be attached to
an electric generator, propeller, or fan.
DEVELOPMENTS
4.1 1903 -The first successful gas turbine was built in Paris, consisting of a three-cylinder,
multistage reciprocating compressor, a combustion chamber, and an impulse turbine. It operated
in the following way: Air supplied by the compressor was burned in the combustion chamber with
liquid fuel. The resulting gasses were cooled somewhat by the injection of water and then fed to
an impulse turbine. This system, which had a thermal efficiency of about 3 percent, demonstrated
for the first time the feasibility of a practical gas-turbine engine.
4.2 1903, Aegidus Elling of Norway- The first successful experimental gas turbine using both
rotary compressors and turbines was built. In this machine, part of the air leaving a centrifugal
compressor was bled off for external power use. The remainder, which was required to drive the
turbine, passed through a combustion chamber and then through a steam generator where the
hot gas was partially cooled. He further refined the machine in subsequent years, and by 1912,
he had developed a gas turbine system with separate turbine unit and compressor in series, a
combination that is still common today.
4.3 1905, Hans Holzwarth of Germany - “Explosion” turbine. In this system, a compressor
introduced a charge of air and fuel into a constant-volume combustion chamber. After ignition,
the hot, high-pressure gas escaped through spring-loaded valves into nozzles directed against
the blading of a turbine. Holzwarth and various collaborators continued to develop the explosion
turbine for more than 30 years until it was eventually superseded by the modern gas-turbine
engine.
4.4 For Locomotive propulsion - During the 1950s and ’60s, manufacturers of locomotives built
a number of vehicles powered by gas-turbine engines that use heavy oil. Although gas-turbine
locomotives have had moderate success for long sustained runs, they have not been able to
make significant inroads against diesel locomotives under normal running conditions, especially
after increases in the relative cost of heavy fuel oils.
4.5 For Automotive propulsion – The gas-turbine engines were proposed for use in automobiles
from the early 1960s. In spite of their small size and weight for a given power output and their low
exhaust emissions compared to gasoline engines, the disadvantages of high manufacturing costs,
low thermal efficiency, and poor part-load and idling performance have proven gas-turbine cars
to be uneconomical and impractical.
4.6 For Marine propulsion - In this area of application, the gas-turbine engine has two
advantages over steam- and diesel-driven plants: it is lightweight and compact. During the early
1970s a ship powered by a gas turbine capable of 20,000 horsepower was successfully tested at
sea by the U.S. Navy over a period of more than 5,000 hours. Gas turbines were subsequently
selected to power various new U.S. naval vessels.
4.7 Gas turbine technology continued to be enhanced by a number of innovative pioneers from
various countries. In 1930, Britain’s Sir Frank Whittle patented a design for a jet engine. Gyorgy
Jendrassik demonstrated Whittle’s design in Budapest, Hungary, in 1937. In 1939, a German
Heinkel HE 178 aircraft flew successfully with an engine designed by Hans von Ohain that used
the exhaust from a gas turbine for propulsion. The same year, Brown Boveri Co. installed the first
gas turbine used for electric power generation in Neuchatel, Switzerland. Both Whittle’s and von
Ohain’s first jet engines were based on centrifugal compressors.
TYPES OF GAS TURBINE POWER PLANT
5.1 Types of Gas Turbine Power Plant by System
5.1.1 Open Cycle System
A type of gas turbine in which the hot gasses produced by the combustion of liquid fuel to
rotate the turbine and the remaining heat will be exhausted to the atmosphere is called an open
cycle gas turbine.
Figure 4. Schematic Diagram of Open Cycle
The main parts of an open cycle gas turbine are: a compressor, a combustion chamber
and a turbine unit. In an open cycle gas turbine, the compressor receives the fresh air from the
atmosphere and compresses it, then this compressed air is mixed with the fuel and injected into
the combustion chamber. In the combustion chamber, the burning of fuel raises the temperature
of compressed air. These high pressure hot gasses are passed through the turbine blades to spin
the turbine.
Finally, after rotating the turbine, the gasses are exhausted into the atmosphere and the
compressor is supplied with the fresh atmospheric air to repeat the process.
The following are the main advantages of open cycle gas turbines:
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Warm-up time: After the starting motor accelerates the turbine to its rated speed and the
fuel is ignited, the gas turbine can be accelerated from a cold start to a full load without a
warm-up time. Open cycle plants are favored when used as peak load plants due to their
quick start times and the ability to take up load quickly.
Low weight and size: The weight per kW generated is low. Open cycle plants require less
space than closed-cycle plants.
Fuels: Hydrocarbon fuels of any type can be used in the combustion chamber, from heavy
diesel oils to high-octane gasoline.
Refinements: Component and auxiliary refinements can usually be implemented in open
cycle gas turbine plants to improve thermal efficiency. They can also provide the most
economical overall cost depending on the load factors and other operating conditions.
●
No cooling medium is needed: There is no need for cooling water for open cycle gas
turbines except those with intercoolers. Therefore, the plant becomes self-contained and
independent of a cooling medium.
5.1.2 Closed System
The type of gas turbine known as a closed cycle gas turbine continually circulates air
inside the turbine. As a result, in a closed loop gas turbine, the fuel gas creates a closed
thermodynamic system, and the exhaust gases are not released into the atmosphere but are
instead cooled by a cooling chamber and returned to the compressor.
Figure 5. Schematic Diagram of Closed Cycle
Compressor, heating chamber, gas turbine, and cooling chamber make up a closed cycle
gas turbine. This kind of gas turbine uses the Brayton cycle to operate. where the working fluid is
continuously utilized inside the turbine system.
In a closed cycle gas turbine, a compressor compresses the gas or air before it enters a
heating chamber. Prior to passing over the turbine blades, the compressed air or gas is heated in
the heating chamber using heat that is supplied from an external source. These hot, compressed
gasses pass over the turbine blades as they flow over them, expanding as they do so to rotate the
turbine. They then pass into the cooling chamber, where they are cooled off before being sent
back into the compressor to complete the cycle.
Closed cycle gas turbines have the following advantages:
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Excellent thermal efficiency at all temperatures and pressure ratios
Use of any working fluid with low caloric value, such as helium
Corrosive-free
No need to clean the inside
In both domestic and industrial settings, re-heaters can be used to heat water for a hot
water supply
The small size of the gas turbine
The higher the pressure, the better the heat transfer coefficient in the exchanger
Less fluid friction loss
5.2 Types of Gas Turbine Power Plant by Turbine
5.2.1 Axial Type
The most popular and practical configuration for big gas turbines is an axial gas turbine.
Axial gas turbines are used in large power plants and industrial facilities to generate electricity
for the grid as well as power and heat for district heating, processes, and facilities. The lower
power bands, however, where both axial and radial gas turbines are available, receive less
attention. In areas where the two technologies overlap, it is valuable to compare axial and radial
turbines.
5.2.2 Centrifugal Type
The centrifugal type is adopted for small scale gas turbines.
5.3 Types of Gas Turbine Power Plant by Compressor
5.3.1 Axial Type
An axial-flow compressor increases the pressure of its working fluid by first speeding it
and then diffusing it (Chapter 7). The rotor, which is made up of a row of revolving airfoils or
blades, accelerates the fluid while the blades, which are fixed, diffuse it (the stator). The velocity
gain in the rotor is converted to a pressure gain via diffusion in the stator. A stage in a compressor
is made up of one rotor and one stator. Typically, a compressor has several stages. In order to
guarantee that air enters the first-stage rotors at the desired angle, an additional row of fixed
blades (inlet guide vanes) is frequently used at the compressor inlet. In addition to the stators, an
additional diffuser at the exit of the compressor further diffuses the fluid and controls its velocity
when entering the combustors.
5.3.2 Centrifugal Type
They raise the pressure by supplying energy to the fluid that is already flowing
continuously through the rotor/impeller. This specific energy input is shown in the following
equation. By slowing the flow via a diffuser, a significant percentage of this energy, which is
kinetic, is transformed into enhanced potential energy/static pressure. The rise in static pressure
at the diffuser and impeller may be about equal. A simple centrifugal compressor stage has four
components (listed in order of throughflow): inlet, impeller/rotor, diffuser, and collector.
5.4 Types of Gas Turbine Power Plant by Use
5.4.1 Aircraft Gas Turbine
The aim of application for aircraft was because it has been noted characteristics that are
compact, high output (greater output power per body weight of the machine is available than
other heat engines). The turbojet engine which utilizes exhaust gas as promotion energy has been
developed; moreover, the high efficiency turbofan engine which drives the fan has been
developed. In any event, the aircraft gas turbine gets reaction promotion force by ejecting.
Figure 6. Aircraft Gas Turbine
5.4.2 Land-based Gas Turbine
“Land use gas turbines”, particularly for power generation, used to be called “Heavy Duty
Gas Turbine”, because the operation time in the year is more than aircraft gas turbines. It has
varied indicators such as efficiency and durability characteristics, etc. different from aircraft gas
turbines. The gas turbine which is developed specially for power generation is endeavoring to
improve the reliability of long-term operation and have simple structure and long-term reliability.
Figure 7. Land-based Gas Turbine
5.4.3 Aircraft-derivative Gas Turbine
The aircraft-derivative gas turbine is one which utilizes the aircraft jet engine, in general,
power recovery turbine for compression and power turbine for generation are separated.
Figure 8. Aircraft-derivative Gas Turbine
AREA/AVAILABILITY OF GAS TURBINE POWER PLANT
According to the Natural Gas Supply Association, the average natural gas land
requirement is 20 up to 30 acres or 8 to 12 hectares.
The construction of the Gas Turbine Power Plant includes offshore and onshore
extraction. Offshore extraction includes drilling of land for underground pipelines and for roads
and onshore extraction for digging wells.
According to a study, The land natural gas used for resource production is minimal.
Excluding the land needed to mine fracking rig materials, the average initial disturbance of a
single-well pad is 3.7 acres during production.41 However, the average multiple well-pad size is
five acres as shown in a study of the Pinedale natural gas field in Wyoming.42 The EIA reported
that most well pads are multi-well pads with four to six wells.43 This study will use multi-well pads
for calculating acreage. This report does not include access roads due to the large number of
roads, and variations in land requirements. This study will assume land use based on multi use
well-pads containing five drills using five acres each.
Factors in building a Gas Turbine Power Plant
Site Exploration
You should have a team of experts to help you choose the most appropriate site according
to the scope of your project. Several site studies should be conducted to ensure the selection of
an excellent site. The ideal case scenario is finding an already developed site that is ready for
setting up a gas power plant. It will minimize the overall cost and time required for setting up the
project.
Feasibility Study
One of the key steps for setting up a gas power plant is its feasibility study. It tells you
whether the project is viable or not. It involves an elaborate analysis of different factors
associated with the project.
Budget
There are different kinds of expenses associated with a gas power plant, and you need to
take all into account. From acquiring land to fuel, everything requires solid investment. However,
there are ways to cut down your expenses. For example, you can use less expensive fuel that
gives an output equivalent to the costly sources.
Availability of fuel
Fuel should be available at cheaper rates.
Distance from the load center
The station shall be located near the center to minimize losses and transmission line cost.
Availability of good quality land
Land must be capable of withstanding station load vibrations transmitted to foundations.
It should be cheaper in cost to have low capital cost.
FACTORS AFFECTING GAS TURBINE PERFORMANCE
7.1. Air Temperature and Site Elevation
A gas turbine performance is affected by anything that alters the density and/or mass flow of
the air intake to the compressor because it is an air-breathing engine. The most noticeable
deviations from the reference pressure and temperature, which are 14.7 psi/1.013 bar and
59F/15C, respectively, are caused by ambient meteorological conditions.
Figure 9. Air Temperature and Site Elevation
This figure shows how ambient temperature affects the output, heat rate, heat consumption, and
exhaust flow of a single-shaft MS7001. Each turbine model has its own temperature-effect curve,
as it depends on the cycle parameters and component efficiencies as well as air mass flow.
Correction for altitude or barometric pressure is more straightforward. The air density reduces as
the site elevation increases. While the resulting airflow and output decrease proportionately, the
heat rate and other cycle parameters are not affected.
7.2. Humidity
Because humid air is less dense than dry air, gas turbine performance is immediately impacted.
As a result, a lower mass flow rate will be employed for the same volume entering the gas turbine,
lowering the power output.
7.3. Inlet and Exhaust Losses
Pressure losses in the system result from the installation of air filtration, silencing, evaporative
coolers or chillers in the inlet or heat recovery devices in the exhaust. The figure below shows the
effects on the MS7001EA, which are typical for the E technology family of scaled machines
(MS6001B, 7001EA, 9001E).
7.4. Fuels
The product of the mass flow, heat energy in the combusted gas (Cp), and temperature differential
across the turbine is known as the work produced by a gas turbine. The compressor airflow and
the flow of injected fuel are added to determine the mass flow in this equation. The components
of the fuel and the byproducts of combustion influence the heat energy. As a result, different fuels
will provide varying amounts of power.
Take note that, natural gas (methane) produces nearly 2% more output than does distillate oil.
This is due to the higher specific heat in the combustion products of natural gas, resulting from
the higher water vapor content produced by the higher hydrogen/carbon ratio of methane.
This figure shows the total effect of various fuels on turbine output. This curve uses methane as
the base fuel. Although there is no clear relationship between fuel lower heating value (LHV) and
output, it is possible to make some general assumptions. If the fuel consists only of hydrocarbons
with no inert gases and no oxygen atoms, output increases as LHV increases. Here the effects of
Cp are greater than the effects of mass flow. Also, as the amount of inert gases is increased, the
decrease in LHV will provide an increase in output.
Figure 10. Fuel Graph
7.5. Fuel Heating
Gas turbine power will be slightly reduced as a result of fuel heating due to the incremental volume
flow reduction. The efficiency of the combined cycle can be increased since it is
thermodynamically favorable to use this energy in the gas turbine fuel heating system.
7.6. Air Extraction
In general, up to 5% of the compressor airflow can be recovered from the compressor discharge
casing without modifying casings or on-base pipes in various gas turbine applications (cooling for
the turbine, pressurized air for the cabin in an airplane, etc.). However, due to the restricted mass
flow rate passing through the turbine, the power output automatically decreases as air extraction
increases.
7.7. Inlet Cooling
Installing an evaporative cooler or inlet chiller in the inlet ducting downstream of the intake filters
will lower the compressor inlet temperature. These systems must be used carefully since water
from condensation or carryover can worsen compressor fouling and impair performance.
As Figure 13 shows, the biggest gains from evaporative cooling are realized in hot, low-humidity
climates. It should be noted that evaporative cooling is limited to ambient temperatures of 59 F/15
C and above (compressor inlet temperature >45 F/7.2 C) because of the potential for icing the
compressor. Information contained in Figure 16 is based on an 85% effective evaporative cooler.
Effectiveness is a measure of how close the cooler exit temperature approaches the ambient wet
bulb temperature. For most applications, coolers having an effectiveness of 85% or 90% provide
the most economic benefit.
Figure 11. Inlet Cooling
PHILIPPINE CONTEXT OF GAS TURBINE
8.1. Power Plants Fed by the Malampaya Gas Field
The Malampaya field provides feed gas to five power plants on the Luzon Island, including four
combined-cycle and one open-cycle power plants that have a combined installed capacity of
3.2GW.
The power plants are the 1.2GW Ilijan power station, the 1,000MW Saint Rita power station (1,000
MW), the 500MW San Lorenzo power plant, the 414MW San Gabriel power plant, and the 97MW
Avion power plant.
Natural Gas Power Plants
●
Ilijan Combined-Cycle Power Plant
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Santa Rita Combined Cycle Power Plant
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San Lorenzo Combined Cycle Power Plant
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Avion Close Open Cycle Power Plant
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San Gabriel Combined Cycle Power Plant
Figure 12. Natural Gas Power Plant Locations
Ilijan combined-cycle power station
The 1.2GW Ilijan power plant, built on a 60-acre site at Arenas Point, Barangay Ilijan, Batangas
City. The Ilijan power plant comprises two 600 MW combined-cycle units. Construction on the
project was started in March 1999, while commissioning took place in June 2000.
Santa Rita power station
The 1GW Santa Rita power station is located in the First Gen Clean Energy Complex, Batangas
City. The Santa Rita combined-cycle power plant utilizes four Siemens v84.3A gas turbines with
a 220 MW rated capacity each.
San Lorenzo combined-cycle power plant
The 500MW San Lorenzo power plant is located adjacent to the Santa Rita power plant. Equipped
with two Siemens v84.3A natural gas turbines.
Avion open-cycle power plant
The 97MW Avion power plant, also located in the First Gen Clean Energy Complex, Batangas
City. The open-cycle power plant comprising two units of GE’s LM6000 PC Sprint aero-derivative
gas turbines commenced operation in September 2016.
San Gabriel combined-cycle power plant
The 414MW San Gabriel combined-cycle power plant located in the First Gen Clean Energy
Complex, Batangas City. The gas-fired plant is equipped with an SCC6-8000H gas turbine from
Siemens. The San Gabriel power plant will shift to regasified LNG when the Malampaya field
ceases gas production.
8.2. Natural Gas Reserves
As of 2017, the Philippines held 3.48 trillion cubic feet (Tcf) of proven gas reserves, ranking 50th
globally and making up around 0.050% of the 6,923 Tcf total global natural gas reserves. The
proved reserves of the Philippines are 31.4 times its annual consumption. This indicates that there
are roughly 31 years of gas left (at current consumption levels and excluding unproven reserves).
Figure 13. Philippine Gas Reserves
Figure 14. Natural Gas Objectives
8.3. Natural Gas Consumption
● The Philippines consumes 110,960 million cubic feet (MMcf) of natural gas per year as
of the year 2017.
● The Philippines ranks 75th in the world for natural gas consumption, accounting for
about 0.1% of the world's total consumption of 132,290,211 MMcf.
● The Philippines consumes 1,055 cubic feet of natural gas per capita every year (based
on the 2017 population of 105,172,925 people), or 3 cubic feet per capita per day.
Figure 15. Natural Gas Consumption
GLOBAL CONTEXT OF GAS TURBINE
Largest Natural Gas Power Station
●
Surgut-2 power station
Located in the Russian city of Surgut which has an overall power capacity of around 5.6 GW.
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Futtsu power station
Located in Futtsu in Japan the first two facilities, with a combined capacity of 2GW and a third
plant, consisting of four 380 MW combined cycle systems.
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Kawagoe power station
Located in Kawagoe, Mie, Japan, it has a power generation capacity of 4,802 MW.
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Tatan power plant
Located in Guanyin, Taoyuan, Taiwan it has a 4,384 MW capacity.
Producers of Natural Gas
Figure 16. Chart of Different Natural Gas Sources
Top Countries with largest Natural Gas Reserves
Figure 16.1 Gas Reserves
With their current gas rate consumption Russia has 102 years, Iran has 162 years, Qatar has
609 years, Turkmenistan has 191 years, and the United States has 12 years.
ADVANTAGES OF NATURAL GAS
○
Natural gas is the most environmentally friendly fossil fuel because it burns
cleaner
Figure 17. CO2 Emissions
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Generates power as nearly as coal
Figure 18. Electric power net generation
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Versatile Energy Source
As a gas or as LNG, it can power electrical grids, heating systems, home cooking
appliances, and some vehicles.
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Rapid and Efficient Transport
When pipelines are available, natural gas is relatively easy to transport in its
gaseous form. Natural gas supply chains are well established, with supply routes
by sea and land serving several major hubs.
DISADVANTAGES OF NATURAL GAS
○
Natural gas is a nonrenewable resource
As with other fossil energy sources (i.e. coal and oil) natural gas is a limited
source of energy and will eventually run out.
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Methane Leaks
Natural gas is easy to transport and comes from global locations. However, these
activities release methane, a potent greenhouse gas, at every level of the supply
chain. Methane leaks are hard to avoid, making natural gas a dirtier energy
source than initially thought.
Figure 19. Gas Supply Chain Leaks
LEVELIZED COST OF ENERGY
Figure 20. Levelized Cost of Energy Comparison
The shown graph is the detailed price of how much per MegaWatt per Hour (MWh) does Natural
Gas compare to other forms of energy source.
Natural gas is less expensive than other fossil fuels.
Figure 21. Graph of Fuel Price
Compared to other fossil fuels Natural Gas has been cheap over the years since when it has
first encountered.
Natural gas is as cheap as some renewable energy
Figure 21.1 Comparison of Cost
ENVIRONMENTAL IMPACTS
A power plant and its supporting components consume space on the ground and in the
air, use water resources, and frequently release air pollutants. The plant's footprint on the
ground precludes others from purchasing or using the land. It may also have an impact on
the current or future uses of neighboring land. If the land for the power plant is a
"greenfield," which is an undeveloped area with mostly vegetation (crops, pasture, or oldfield vegetation), there will be effects on land use, soils, and wildlife on the site.
Proper assessments and comparisons of the issues described above typically require a
life-cycle assessment (LCA) approach.
13.1 Land Use
Figure 22. Land Use
Land occupation includes both agricultural and urban land occupation, direct and
indirect. Natural gas does not entail a high amount of land use, as natural gas is
extracted from underground, and power plants do not use significant space. In
comparison with coal power that uses large areas of land for extraction and mining.
In addition, heavy machinery is needed to build roads, facilities, and drilling sites,
which can significantly damage pristine wilderness. Often, the harm cannot be
undone. So, to lessen the damage, hauling trucks need to comply with road weight
limit standards to avoid ground vibration.
Wildlife and land use may be impacted by well drilling. Local ecosystems may
collapse as a result of this intervention because natural gas extraction has the
unintended consequences of disrupting migration patterns, polluting rivers and
streams, and causing dirt and pollution to erode. Fracking, or hydraulic fracturing,
stresses the nearby water resources and increases the risk of earthquakes.
Possible installation of safety features for fuel storage tanks, such as, but not
limited to, spill prevention and detection, bund wall, and secondary containment
13.2 Water Quality
Figure 23. Water Quality
Water is an essential ingredient in the production of feedstocks and is used to cool
power plants. There are three categories of water impacts: consumption,
withdrawal, and contamination.
Water that is evaporated, transpired, or incorporated during the operation of a gas
turbine power plant is referred to as consumption. Although the water remains in
the global water cycle, consumption generally reduces the amount of water
immediately available for other uses, such as meeting agricultural needs.
The term "withdrawal" describes the volume of water that is briefly diverted from
its natural source, such as when cooling systems in power plants are in use. When
waste water is returned at a temperature higher than that of its source, it can have
an impact on aquatic ecosystems.
The production of fuel can harm ecosystems, contaminate water supplies, and put
people's health at risk. Water quality can be impacted by upstream processes like
mining and processing, and combustion creates air pollutants that can eventually
end up in water bodies. Sometimes the gas producers send the contaminated
water to wastewater treatment facilities that also handle sewage and water from
other industrial sources as a means of disposal.
For the mitigation measures, the plant shall have a sanitary wastewater treatment
system and shall be designed and installed in accordance with Applicable Local
Law to prevent any hazard to public health or contamination of land, surface, or
groundwater.
13.3 Air Emission
Figure 24. Air Emission
The NOX and SO2 emissions from power plants that burn coal or natural gas are
a concern. These compounds are part of a complex chemical reaction in the
atmosphere that produces fine particulates made of nitrates and sulfates. Nitrogen
oxides (NOx) contained in the exhaust gas are the cause of photochemical smog
and acid rain.
SO2 has been identified as a contributor to acid precipitation, also known as "acid
rain," which can harm vegetation and acidify lakes. Acidic-sensitive species have
difficulty reproducing and, in some cases, die. NOX and volatile organic
compounds (VOCs) contribute to the formation of ozone.
Figure 24.1. Acid Rain
Nearly everything is affected by acid rain. Precipitation has the ability to transform
plants, soil, and trees. Trees have been found to be severely harmed by acid rain.
By removing the barrier that covers the leaves, it weakens them and slows growth.
Additionally, acid rain can alter the chemical composition of soil and water bodies,
rendering them uninhabitable for native plants and animals.
For mitigation measures, The air emissions from the Plant Facility shall be
guaranteed to not exceed any of the Emissions Guarantees. And continuous
emissions monitoring system (CEMS) equipment shall be provided for the
measurement of air emission levels.
13.4 Life Cycle Global Warming Emission
Carbon dioxide (CO2) and other air pollutant emissions are part of the exhaust
heat released into the environment. Due to its cleaner burn, natural gas is the most
environmentally friendly fossil fuel. Gas Turbine emits between 50 and 60 percent
less carbon dioxide (CO2) in power plants than conventional oil or coal-fired power
plants.
Only 66.6% of the exhaust heat can be used to generate steam, with the remaining
33.4% being emitted into the environment. Additionally, it releases into the
atmosphere greenhouse gasses with a shorter life cycle. But combustion also
results in methane emissions and worsens air quality. There is no practical way to
store the entire amount of exhaust heat produced by power generation.
Figure 25. Comparison of GHG Emission of Gas Turbine and Coal Power Plant
Gas turbines produce approximately 56% of coal's CO2 emissions per unit of
energy. Natural gas, when burned in various types of existing US power plants,
emits anywhere from 42% to 63% of the CO2 emissions produced by coal,
depending on the power plant technology.
In order to assess the climate impacts of a fuel used in the power sector more
thoroughly, analyses must aggregate emissions across the entire supply and
utilization chain.
13.5 Life Cycle Assessment
Figure 26. Life Cycle Assessment
73% of all electricity is produced using natural gas, making it the most common
fuel. Since electricity is a necessity for daily human activities, the demand for
electricity has grown along with the country's population. To prevent negative
effects on human health and the environment, the implications of using natural gas
as the primary feedstock must be fully understood and carefully considered.
More than 90% of the life cycle of a gas turbine power plant is devoted to plant
operation. The main material streams during this time period are related to turbine
operation, maintenance, and plant operation itself.
The building and decommissioning subsystem includes building and
decommissioning power plants in addition to building the fuel supply route.
Decommissioning has the lowest environmental impact of all the phases.
Environmental
Impacts
Mitigation Measures
●
●
Land Use
●
●
Implementation of solid and hazardous waste
management plan
Segregation of hazardous materials by waste
type
Storage of wastes stored in sealed and
labeled containers
Wastes are treated and disposed by DENREMB accredited transporters, haulers and
treaters
●
●
Water Quality
●
●
Air Emissions
●
●
Regularly remove silt and sediments
Establishment of siltation ponds, silt traps
and erosion barriers
Possible installation of safety features for fuel
storage tanks, such as, but not limited to, spill
prevention and detection, bund wall, and
secondary containment
Proper and regular maintenance of power
plant engines
Regular ambient air and source emission
monitoring
Possible installation of air pollution control
devices
FUTURE OF GAS TURBINES
Gas will continue to grow quickly, but the global demand for coal will likely peak around
2025. coal, oil, and gas will continue to be 74 percent of primary energy sources, down
from 82 percent now. After that, the rate of decline is likely to accelerate as we transition
to renewable energy sources.
14.1 Carbon Capture and Storage
Figure 27. Carbon Capture and Storage
Gas turbines are one of the most widely-used power generating technologies and
existing research aims in decarbonizing these power plants, one of them is CCUS.
Carbon Capture, Utilization, and Storage (CCUS) is one of these solutions that will
help in lowering carbon emissions across multiple sectors.
Carbon capture and sequestration is the process of removing CO2 from waste
gasses produced by industrial or power generation processes. It is made up of four
main parts: capture, compression, transport, and storage or use. CCUS can be
applied to both new and existing gas power plants.
Figure 27.1
To capture the CO2, it can be extracted from power generation and industrial sites
Once it’s been captured, the CO2 is compressed and then transported either by
ships or pipelines. Finally, the CO2 can be stored safely far underground or the
CO2 can be reused. The captured CO2 is generally reused to produce synthetic
fuels, chemicals, and building materials. However, most of it is likely to be used for
sequestration and enhanced oil recovery (EOR), because of the limited volume of
CO2 demanded for utilization.
14.2 Hydrogen as Fuel
Gas turbines could be decarbonized by burning hydrogen instead of natural gas
because hydrogen has no carbon and emits no CO2 during combustion. When
burning hydrogen in comparison to burning natural gas, more NOx may be
produced.
Today, the majority (about 95%) of the hydrogen is made using natural gas through
the Steam Methane Reforming process, which results in the release of CO2 into
the atmosphere. It is known as "grey" hydrogen. "Blue" hydrogen is produced when
this process is combined with a carbon capture system. By electrolyzing water into
hydrogen and oxygen with the help of renewable energy, so-called "green"
hydrogen can be created. It makes no difference to a gas turbine what "color"
hydrogen is used as fuel.
Figure 28. Impacts of Hydrogen
Gas turbines have run on fuels with hydrogen concentrations ranging from 5% to
100%. This includes the use of hydrogen/natural gas fuel blends as well as
hydrogen-containing industrial fuels.
New gas turbine power plants could be "hydrogen enabled," which means they are
designed to run on natural gas when they first go commercial, with provisions in
place to allow for easier hydrogen fuel upgrades in the future. A hydrogen-enabled
power plant may necessitate configuration changes that are easier to implement
during construction than later when the plant is fully operational.
Gas turbines can run on hydrogen and hydrogen blends, and a future transition to
hydrogen as a zero-carbon gas turbine fuel may be possible. Just like CCUS, it is
possible to operate new units and upgrade existing units for operation on these
fuels with appropriate consideration to the combustion system, fuel accessories,
emissions, and plant systems over time as hydrogen becomes available.
Recent Demonstration and Commercial Projects that Use or Plan to Use Hydrogen
Long Ridge Energy (USA)
Long Ridge Energy intends to begin
blending hydrogen in their new 7HA.02 gas
turbine later this year. The owner’s plan is to
transition the plant to 100% hydrogen in 10
years.
NYPA Brentwood (USA)
New York Power Authority intends to
demonstrate blending hydrogen and natural
gas in an existing LM6000 gas turbine in
2022.
Tallawarra B (Australia)
EnergyAustralia intends to begin blending
hydrogen in their new 9F.05 gas turbine
starting in 2025. This will be the first 9F gas
turbine to operate on blends of hydrogen and
natural gas.
Guangdong Huizhou (China)
Guangdong Energy Group intends to
operate their new 9HA.01 gas turbines on a
10% blend of hydrogen and natural gas
starting in 2023.
PERFORMANCE AND DESIGN OF GAS TURBINES
15.1 COMPRESSOR
A compressor is a device used to increase the pressure of compressible fluid, either gas
or vapour, by reducing the fluid specific volume during passage of the fluid through
compressor. The main purpose of a compressor is to compress the fluid, then deliver it to
a higher pressure than its original pressure. The inlet and outlet pressure level is varying,
from a deep vacuum to a high positive pressure. This inlet and outlet pressure is related,
corresponding with the type of compressor and its configuration.
15.1.1 CENTRIFUGAL COMPRESSOR
Figure 29. Centrifugal Type Compressor
A centrifugal compressor is a dynamic machine that achieves compression by applying
inertial forces to the gas (acceleration, deceleration, and turning) utilizing rotating
impellers. It is made up of one or more stages; each stage consists of an impeller as the
rotating element and the stationary element, i.e. diffuser. There are two types of diffusers:
vaneless diffusers and vaned diffusers. The vaneless diffuser is widely used in wide
operating range applications, while the vaneless diffuser is used in applications where a
high-pressure ratio or high efficiency is required. Those parts of a centrifugal compressor
are simply pictured below.
In a centrifugal compressor, the fluid flow enters the impeller in an axial direction and is
discharged from an impeller radially at a right angle to the axis of rotation. The gas fluid
is forced through the impeller by rapidly rotating impeller blades. The gas next flows
through a circular chamber (diffuser), following a spiral path where it loses velocity and
increases pressure. The deceleration of flow or “diffuser action” causes pressure build-
up in the centrifugal compressor. Briefly, the impeller adds energy to the gas fluid, and
then the diffuser converts it into pressure energy.
The maximum pressure rise for a centrifugal compressor mostly depends on the
rotational speed (RPM) of the impeller and the impeller diameter. But the maximum
permissible speed is limited by the strength of the structural materials of the blade and
the sonic velocity of fluid; furthermore, it leads to limitation for the maximum achievable
pressure rise. Hence, multistage centrifugal compressors are used for higher-pressure
lift applications. A multistage centrifugal compressor compresses air to the required
pressure in multiple stages.
Figure 29.1 Multi-stage Centrifugal Compressor
Typical centrifugal for the single-stage design can intake gas volumes between 100 to
150,000 inlet acfm. A multi-stage centrifugal compressor is normally considered for inlet
volume between 500 to 200,000 inlet acfm.
It designs to discharge pressures up to 2352 psi, which the operation speeds of the
impeller from 3,000 rpm to higher. There is a limitation for the velocity of the impeller due
to impeller stress considerations; it is ranged from 0.8 to 0.85 Mach number at the impeller
tip and eye. Centrifugal compressors can be driven by an electrical motor, steam turbine,
or gas turbine.
●
ADVANTAGES
○
High efficiency approaching two stages of reciprocating
compressor
●
○
Can reach pressure up to 1200 psi
○
Completely packageable for plant use up to 500 hp
○
Does not require special foundations
○
Cost improves as size increase
DISADVANTAGES
○
High initial cost
○
Complicated monitoring and control systems
○
Limited capacity control modulation, requiring unloading for
reduced capacities
○
High rotational speed require special bearings and
sophisticated vibration and clearance monitoring
○
Specialized maintenance considerations
15.1.2 AXIAL FLOW COMPRESSOR
Figure 30. Axial Type Compressor
Axial flow compressors are used mainly as compressors for gas turbines. They are used
in the steel industry as blast furnace blowers and in the chemical industry for large nitric
acid plants. Compare to other types of compressors, axial flow compressors are mainly
used for applications where the head required is low and with a high intake volume of flow.
The efficiency of an axial flow compressor is higher than that of a centrifugal compressor.
They are available in sizes producing pressures above 100 psi at intake volumes between
23,500 to 588,500 acfm. The component of an axial flow compressor consists of the
rotating element that is constructed from a single drum which is attached to several rows
of decreasing-height blades having airfoil cross sections. Between each rotating blade row
is a stationary blade row. All blade angles and areas are designed precisely for a given
performance and high efficiency.
One additional row of fixed blades (inlet guide vanes) is frequently used at the compressor
inlet to ensure that air enters the first-stage rotors at the desired angle. Also, another
diffuser at the exit of the compressor might be added, known as an exit guide vane, to
further diffuse the fluid and control its velocity. Axial flow compressors do not significantly
change the direction of the flow stream; the fluid flow enters the compressor and exits
from the gas turbine in an axial direction (parallel with the axis of rotation). It compresses
the gas fluid by first accelerating the fluid and then diffusing it to increase its pressure. The
fluid flow is accelerated by a row of rotating airfoils (blades) called the rotor, and then
diffused in a row of stationary blades (the stator). Similar to the centrifugal compressor,
the stator then converts the velocity energy gained in the rotor to pressure energy. One
rotor and one stator make up a stage in a compressor. The axial flow compressor
produces low-pressure increases, thus the multiple stages are generally used to permit
overall pressure increase up to 30:1 for some industrial applications.
The driver of axial flow compressors can be steam turbines or electric motors. In the case
of direct electric motor drive, low speeds are unavoidable unless sophisticated variablefrequency motors are employed. Here are the advantages and disadvantages of an axial
flow compressor.
●
●
ADVANTAGES
○
High peak efficiency
○
Small frontal area for given airflow
○
Increased pressure rise due to increased
○
number of stages with negligible losses
DISADVANTAGES
○
Good efficiency over narrow rotational speed range
○
Difficulty of manufacture and high cost
○
Relatively high weight
○
High starting power requirements
15.1.3 THERMODYNAMIC PROCESSES
Figure 31. Diagram of Brayton Cycle
1 - 2 Isentropic Process (entropy is constant)
15.2 COMBUSTION
a chamber (as in a gas turbine or a jet engine) in which combustion occurs merriam webster dictionary
The combustion section task is to control the burning of large amounts of fuel and
air. release heat in such a way that the air is expanded and accelerated, resulting
in a smooth and stable stream of uniformly heated gas under all starting and
operating conditions. Must be accomplished with minimum pressure loss and
maximum heat release. Combustion liners need to prevent the fire from contacting
metal.
15.2.1 Multiple Combustion Chamber(can type)
This type of combustion chamber is found in centrifugal compressor engines and
earlier versions of axial flow compressor engines. It is a direct development of the
original Whittle combustion chamber(left). The individual flame tubes are all
interconnected. This allows each tube to operate at the same pressure while also
allowing combustion to spread around the flame tubes during engine startup.
Figure 33. Multiple Combustion Chamber
●
Advantages
- The major advantage of can type combustion chambers was that
development could be carried out on a single can using only a
fraction of the overall air flow and fuel flow.
-
Low development cost favorable aerodynamic conditions in the
flame tube favorable fuel distribution Good accessibility for
servicing.
15.2.2 Tubo-annular Combustion Chamber(can-annular type)
covers the evolutionary gap between multiple and annular types A number of flame
tubes are installed inside a common air casing. The airflow is similar to that
described previously. This arrangement combines the multiple system's ease of
overhaul and testing with the annular system's compactness.
Figure 34. Turbo-annular Combustion Chamber
●
Advantages
- permits easy access to the fuel nozzles and combustion cans
maintenance.
-
Development costs are lower and the volume smaller than with a
can- type combustion chamber.
15.2.3 Annular Combustor
This particular style of combustion chamber is made up of a single, entirely annular
flame tube that is enclosed in an inner and an outer casing. Since the chamber is
open at the front to the compressor and the back to the turbine nozzles, the airflow
through the flame tube is similar to that previously described.
suitable for engines with axial-flow compressors.
Figure 35. Annular Combustor
●
Advantages
- the length of the chamber is only 75% of that of a tuboannular system of the same diameter for the same power
output, resulting in significant weight and production cost
savings.
Another advantage is that combustion propagation issues
between chambers are eliminated.
15.2.4 Thermodynamic Process
Figure 36. Thermodynamic Process
Process 2-3 = isobaric Heat Addition (Pressure is constant)
Formula:
15.3 TURBINE
Turbines are machines that are used to transform rotational energy from
fluids that were picked up by the rotor system into usable energy or electricity. As
the blades spin, it drives a generator which converts the energy.
In power plants, the hot gas is expanded in the turbine in order to provide
the power required to rotate the compressor blades as well as producing electric
power. The hot gasses do not lose all their heat even after passing through the
final stage of the turbine, so their heat can be further utilized by directing them
towards boilers in thermal power plants.
15.3.1 Axial Flow Steam Turbine
Figure 37. Axial Flow Steam Turbine
These turbines operate to convert the thermal energy available in
the steam into mechanical energy. They are used for electricity generation
in thermal power plants. The steam is guided through the turbine to
multistage rotating blades driving the electric generator. Such power plants
utilize these by using natural gas, fossil fuel, coal, or nuclear fuel.
15.3.2 Turbojet
Figure 38. Turbojet
The turbojet engine consists of four sections such as the
compressor, combustion chamber, turbine section, and exhaust. The
compressor section passes inlet air at a high rate of speed to the
combustion chamber. The combustion chamber contains the fuel inlet and
igniter for combustion.
Advantages
-Relatively simple design
-Capable of very high speeds
-Takes up little space
Disadvantages
-High fuel consumption
-Loud
-Poor performance at slow speeds
-limited in range and endurance
15.3.3 Turbofan
Figure 39. Turbofan
Turbofans were developed to combine some of the best features of
the turbojet and the turboprop. These engines are designed to create
additional thrust by diverting a secondary airflow around the combustion
chamber. It is a turbojet engine that is connected via a gear system to a
propeller.
Advantages
-Fuel efficient
-Quieter than turbojets
Disadvantages
-Heavier than turbojets
-Larger frontal area than turbojets
-Inefficient at very high altitudes
15.3.4 Turbopropeller
Figure 40. Turbopropeller
The turbopropeller (turboprop) engine is a combination of a gas
turbine engine, reduction gear box, and a propeller. These are basically
gas turbine engines that have a compressor, combustion chamber(s),
turbine, and an exhaust nozzle (gas generator), all of which operate in the
same manner as any other gas engine.
Advantages
●
●
●
Very fuel efficient
Most efficient at mid-range speed between 250-400 knots
Most efficient at mid-range altitudes of 18,000-30,000 feet
Disadvantages
●
●
Limited forward airspeed
Gearing systems are heavy and can break down
EQUIPMENT SELECTION
The packaging of a gas turbine is the practice of combining and integrating machineries
and components for specific application and plant settings. Packaging a gas turbine typically
involves customization of the design to create the most appropriate site-specific solution.
Packaging decisions typically revolve around the compressor trains, large pumps, special
electrical power-generator and other units for CPI plants..
Currently, the aero-derivative gas turbine is preferred for CPI applications over other types
of gas turbines (such as heavy-duty frame gas turbines), because it provides superior
performance in terms of operational flexibility, efficiency, compact sizes, light weight and
advanced packaging concepts. An aero-derivative gas turbine consists of two parts — an aircraftderivative gas generator section, and a free-power turbine section. The gas generator is derived
from an aircraft engine that has been modified to burn fuels that are typically available in CPI units
(such as natural gas).
The aero-derivative gas turbine is praised for its quick start-up and shut-down times, ability
to adapt to variations in load, high efficiency, and variable-speed capability. These designs are
excellent alternatives to conventional industrial, heavy-frame gas turbines due to all of these
features.
One of the key factors promoting the usage of aero-derivative gas turbines is high
efficiency. As a very rough estimate, aero-derivative gas turbines have an efficiency that is
between 9 and 15% higher than heavy-frame gas turbines of comparable size.
The starting cost makes up roughly 10% of the overall lifecycle cost for the majority of gas
turbines. Approximately 18% of the entire cost of the lifespan is made up of operating and
maintenance expenses. Given that fuel typically represents the largest cost component (72% of
the overall lifetime cost), turbine efficiency plays a crucial role.
Although there have been substantial advancements in the energy efficiency of gas
turbines over the past 30 years, these advancements are primarily the result of greater gas turbine
integration inside a contemporary CPI plant (particularly the heat recovery). The secret to
packaging a gas turbine is integration. Integrating a gas turbine into a plant, specifically with
adjacent and related facilities, for better overall combined operation, is referred to as integration
in simple terms.
Sample Design of a Gas Turbine Power Plant
Outline of the Project
From the result of Sub-section 4.7.2 and 4.7.3, Bheramara CCPP is planned as a nominal 360MW
high efficiency combined cycle power plant consisting of an F class gas turbine generator, a heat
recovery steam generator (HRSG), a steam turbine generator and related facilities. The Project
additionally includes the branch 230kV transmission line from adjacent main 230kV transmission
line, new 230kV substation, rehabilitation of the existing 132kV transmission line and branch gas
pipeline from the adjacent city gate station (CGS). Forced draft cooling tower system is utilized
for the condenser cooling system and groundwater is used for water supply of the system.
Plant Design Considerations
16.1 Design Conditions
Design Ambient Dry BulbTemp.
35OC / 80%
/Relative Humidity
for Performance Guarantee
Design Minimum Ambient Dry BulbTemp.
10OC / 80%
/Relative Humidity
for Maximum Capability of Generator
60% / 95%
Minimum / Maximum Relative Humidity
Minimum Ambient Dry BulbTemp.
5OC / 43OC
/ Maximum Ambient Dry Bulb
0.1013 MPa
Barometric Pressure
EL+16 m
Elevation
Minimum/Maximum
River
Water Level (*: average of
1976-2006)
LLWL
=
EL+4.22
m
LWL
=
EL+5.47 m*
MWL
=
EL+8.74 m*
HWL
=
EL+13.63 m*
HHWL = EL+15.19
m
BNBC 1993;
Zone III
Basic Seismic
Coefficient
Seismic Criteria
Figure 41. Design Conditions
16.2 Codes and Standards
(1)
Mechanical, Electrical and Control Plant and Equipment
Except there are particular codes and standards in Bangladesh, the Plant and equipment
shall be designed to the following acceptable International Codes and Standards.
1) Japanese Industrial Standards (JIS)
2) The U.S.A. codes and standards (ASME, ASTM etc)
3) The IEC recommendation
4) International Standards Organization (ISO)
5) The British codes and standards (BS)
6) The Federal Republic of Germany codes and standards (DIN)
(2)
Civil and Architectural Works
The engineering, design and construction of civil and architectural works shall conform to
the Bangladesh relevant codes and standards except where particular codes and
standards are laid down in this Basic Design Document or the case where the particular
ones must be applied.
The latest revision of applicable Codes and Standards stated herein at time of the bid due
date shall be applicable.
16.3 Site Layout
Layout of the Bheramara CCPP is planned as Figure I-5-5-1. Detail Drawing is attached as
Attachment 4 BPS-G-002”General Arrangement Power Plant”. Main considerations for
arrangement of the equipments are as follows.
• The first location of 230kV S/S will be selected to the northwest side of the site
taking into account future extension of the S/S.
• As for the arrangement of the power block, the location of the cooling tower should
be considered first because location of air intake for the gas turbine should be
considered to minimize the influence of the exhaust of the cooling tower. According
to the meteorological data, the main wind direction during the summer season at
the site is south. That’s why the location of the cooling tower is on the north side of
the site.
• Accordingly, a steam turbine generator will be arranged adjacent to the cooling
tower. Gas turbine generator and HRSG will be arranged to the south of the
steam turbine generator. Gas turbine generator and steam turbine generator
together with those associated equipment are installed inside the turbine
building.
• The Central Control Room, electrical room and battery room are set up in the
turbine building.
• Diesel oil tanks will be sited next to the existing diesel oil tanks. Those will be two
20,000 kl tanks, one tank contains diesel oil about enough capacity for 7 days
operation. And required area and height of the retention basin will be calculated
according to the NFPA30. A calculation result is summarized in Table I-5-5-2.
Figure 42. General Arrangement of the Equipment
16.4 Calculation for Diesel Oil Tank
Interval of two tanks
Height of retention dike
Diameter of Tank x 2/6
Over 0.9m
NFPA30
Requirement
Capacity of retention dike
Over 100% of effective capacity
of tanks
Distance
between
retention dike and tank
Over 15m
Diameter of tank
37m
Height of tank（maximum
18m
oil level）
Capacity
20000kL
Effective capacity
Margin rate
Calculation
Result
19000kL
5%
Height of retention dike
2.0m
Length of area (east and
west)
100m
Length of area (north and
south)
116.5m
Interval of two tanks
12.3m
Base area
9500m2
Capacity of retention dike
19000m3
Distance
between
retention dike and tank
31.5m
(east and west)
Distance
between
retention dike and tank
15.1m
(north and south)
Figure 43. Calculation Result for Diesel Oil Tank
16.5 Gas Turbine
The basic design functions to be required to the gas turbine which will be employed for this
project are as described hereon.
The gas turbine shall be of an open cycle heavy duty single-shaft type of which turbine inlet
temperature level is of F-class. The gas turbine shall be supplied by original equipment
manufacturers. The gas turbine shall be capable of operating on a simple cycle mode
because it is scheduled to put into commercial operation in advance separately from the
bottoming system considering present impending power supply shortage situation in
Bangladesh. For the purpose, an exhaust gas bypass system shall be equipped. The
following four (4) models of gas turbines could be identified with Gas Turbine World 200708 GTW Handbook (Volume 26) as F-class gas turbines.
Name of OEM
Type of Model
Alstom Power
GT26 with air quench cooler
GE Energy Gas Turbine
Mitsubishi Heavy Industry
PG9351 (FA)
M701F4
Siemens Power Generation
SGT5-4000F
The gas turbine power output shall be specified on a basis of continuous base load with the
load weighting factor of 1.0 for calculation of the equivalent operating hours (EOH) which
will be a scale of the inspection interval of hot gas path parts.
The gas turbine shall be normally operated on indigenous natural gas specified in the subsection 5.5.8 “Fuel Supply System” and be equipped with the function to be operated on
Diesel oil equivalent to No.2-GT oil specified in ASTM D-2880 for emergency operation in
case of lack of the natural gas.
The gas turbine shall be of an advanced design to meet the NOx emission requirement of
less than 40 ppm (15% O2 basis on dry volume) on a dry condition for operation on the
specified natural gas under 75 – 100 % load. It shall be also capable of operating to meet
the NOx emission requirement of less than 100 ppm (15% O2 basis on dry volume) with
injection of water for operation on the oil fuel.
The gas turbine shall be of proven design with manufacturer’s design practices to basically
meet the requirements of ISO 21789 Gas turbine applications – Safety.
It can be allowable that the gas turbine will be equipped with the evaporative type inlet air
cooling system to augment the gas turbine power output. According to climate data recorded
for six (6) years from 2002 to 2007 at Ishurdi near Bheramara site, the temperature
difference between averaged dry and wet bulb temperatures is estimated at 2.8OC. This
means that the gas turbine inlet ambient temperature could be decreased by at least 2.4OC
utilizing the current evaporative cooling system with many experiences. Consequentially,
the power output increase of some 1.3% (equivalent to some 5 MW) will be expected with
increase of the fuel consumption of some 0.9%. Such situation implies that the adoption of
the inlet air cooling system is economically and technically advantageous.
The gas turbine to be proposed shall be of similar model to the gas turbines, of which at
least one (1) gas turbine has the experience of successful commercial operation with not
less than 6,500 hours of actual operating hours on the Bid closing date.
The gas turbine design shall be with a minimum number of bearings, and shall be located
on a steel frame or on adequate steel structures and concrete foundation, sized for the
transient maximum transmittal torque imposed on the shaft in case of short circuit of the
generator or out-of-phase synchronization, whichever is larger. The power output shall be
taken out at the cold end of the shaft.
The gas turbine shall be directly coupled to the generator without any power transmission gear.
16.6 Steam Turbine
The steam turbine shall be of a reheat, triple-pressure, two-casing, condensing type directly
connected to the generator. The steam shall be downward or axially exhausted to a surface
condenser which is cooled by the fresh circulating water which is in turn cooled with a forced draft
wet type cooling tower.
The steam turbine shall be of the manufacturer's standard proven design and construction to allow
economical and reliable service with less maintenance works.
The steam turbine to be proposed shall be of similar design to the steam turbines of which at least
one (1) unit shall has the commercial operation hours not less than 6,500 hours on the Bid closing
time.
The steam turbine and auxiliary systems shall be designed to run continuously under all specified
operating conditions over the specified lifetime of the plant.
The steam turbine maximum capability shall be such that it satisfies the conditions of steam
pressure, temperature, flow as developed by the HRSG when the gas turbine is operated on the
maximum c
apability ambient conditions. In case that the HRSG is supplementary fired, the steam turbine
shall be sized to cope with the maximized capability of the HRSG in consideration of the
supplementary firing over the specified ambient conditions.
The steam turbine shall be designed so that the expected life expenditure of the main components
(casing and rotor) shall not exceed 75% of the expected lives of them at the end of the specified
service hours when it will be operated on the specified conditions.
The steam turbine shall be provided with necessary number of bore scope ports for easy
inspection of the operating conditions of the blades and rotor at periodical intervals, if applicable.
16.7 Fuel Supply System
(1)
Fuel gas supply system
The new plant shall be operated on the specified natural gas.
The gas turbine and heat recovery steam generator shall be designed to operate on the
specified natural gas. The typical specification is as shown in the Table I-5-5-8.
The fuel gas supply system shall cover all the equipment required for the start-up, shutdown
and continuous operation of the gas turbine. A booster compressor station, a pre-treatment
system, and a gas pressure-regulating device shall be also included in the scope of the
Contractor. The pre-treatment system shall be facilitated to clean the specified gas to the extent
that it will be used for the gas turbine without any difficulties. The specific energy (caloric value)
is expressed on the conditions of 35˚C of ambient temperature and 101.3kPa of ambient
pressure.
Properties
Compositions
(mol. %)
Methane
95.982
Ethane
2.444
Propane
0.528
Normal Butane
0.130
Isobutane
0.139
Normal Pentane
0.000
Isopentane
0.100
Oxygen
0.000
Nitrogen
0.361
Carbon Dioxide
0.316
Hydrogen Sulfide
(no data)
Total
100.0
Hydrogen Sulfide (g/ m3)
0.000
Specific Energy (kJ/kg)
Gross specific energy
54,466
Net specific energy
49,099
Specific Gravity (kg/m3N)
0.7511
Temperature (˚C)
Min. -12˚C,
Max. 32˚C
Perf. point 25˚C
Pressure at Terminal (MPa)
Max. 1.2 MPa(g)
Min. 0.8 MPa(g)
Figure 44. Specifications of Gas
(2)
Fuel oil supply system
The new plant shall be operated on the HSD for emergency.
The gas turbine and heat recovery steam generator shall also be designed to operate on the
specified HSD. The typical specification is as shown in the Table I-5-5-9.
The fuel oil supply system shall cover all the equipment required for the start-up, shutdown and
continuous operation of the gas turbine same as the fuel gas supply system. The HSD fuel oil
tanks which have a capacity of 20,000m3 x 2, a pre-treatment system, and an oil pressureregulating device shall be also included in the scope of the Contractor. The pre-treatment system
shall be facilitated to clean the specified oil to the extent that it will be used for the gas turbine
without any difficulties.
Test
Method
Limit
Sp. Gr. @ 60oF/60OF
ASTM D 1298
Min. 0.820 / Max. 0.870
Color ASTM
ASTM D 1500
Max. 3.0
Flash point p.m. (c.c.) OF
ASTM D 93
Min. 100
Pour point oF
ASTM D 97
Max. -40
Viscosity kinematic @100OF cst
ASTM D 445
Less than 9.0
Viscosity
RW-1 Second
@100OF converted
Converted
Max. 50
Sediment %wt.
-
Max. 0.01
Water %Vol.
-
Max. 0.10
Carbon residue, conradson
ASTM D 189
Lass than 0.1
Ash %wt.
ASTM D 482
Max. 0.01
Strong acid number mgs. KOH/g
-
NIL
Total acid number mgs. KOH/g
-
Max. 0.5
Cetane Index (calculated)
ASTM D 976
Min. 45
Sulfur content %wt.
ASTM D 1551
Max. 1.0
Neutralization Value:
Copper Strip corrosion(3 hrs @ 212 ASTM D 130
O
F)
Max. No.1 strip
Distillation:
90% recovered (vol) at OC
ASTM D 86
Max. 360
L.H.V. (Low Heating Value)
18,500 BTU/Lb
Min. Ambient Temperature
41OF
Figure 45. Specifications of HSD
As described on section 4.5.5 the HSD will be used for emergency, on this section the result of
calculation for amount of HSD for emergency and capacity of HSD storage tanks is shown as
follows;
Assumption
Type of Model M701F
Net Output (ISO)
312,100 kW
Heat Rate
8,683 Btu/kWh
LHV of HSD
18,500 Btu/lb
Result of calculation
312,100 kW x 8,683 Btu/kWh / 18,500 Btu/lb x 0.453592 lb/kg = 67,000 kg/h
67,000 kg/h x 24 hours / 0.85 kg/m3 = 1,900 KL/day
2,000 KL/day when a margin of ambient of winter is taken into account
As a result of studying the amount of HSD for emergencies that must be storaged at the
Bheramara CCPP, it is necessary to install HSD tanks capable of storaging the HSD for
emergency use from out of order to restore service of gas supply facility for seven days (2,000
KL/day x 7 days = 14,000KL: i.e., 20,000 KL when a margin of safety is taken into account). With
consideration given to the maintenance of the HSD tanks, it has been determined that two 20,000
KL HSD tanks should be installed in the Bheramara CCPP.
16.8 Water Treatment System
The process water for demineralized water, potable water and sanitary water, fire fighting water
and miscellaneous service water shall be produced through pretreatment system from under
ground water.
The process water for cooling tower shall be produced from under ground directly.
The demineralized water shall be used as HRSG make-up water, auxiliary cooling water, chemical
dosing preparation etc.
The EPC Contractor shall confirm the quality of the produced demineralized water whether it is
acceptable to the HRSG.
The pre-treatment system consists of coagulator and filter, etc.
The demineralizer system consists of chemical storage and regeneration equipment, etc.
Necessity and specification of pre-treatment system will be decided based on quality of ground
water.
The EPC Contractor shall take appropriate countermeasures if required.
The conceptual flow diagram is shown on Figure I-5-5-2 “Water Mass Balance Diagram”.
16.9 Electrical Equipment
(1)
Electrical System
1)
Evacuation of Power
Figure I-5-5-3 shows the scheme of power station and 230 / 132kV substation. The electrical
system will be designed on the basis of the multi shaft configuration of the having two (2)
generators, Gas Turbine Generator (hereinafter called as “GTG”) and Steam Turbine Generator
(hereinafter called as “STG”) and two (2) generator step-up transformers, Gas Turbine
Transformer (hereinafter called as “GT transformer”) and Steam Turbine Transformer (hereinafter
called as “ST transformer”). The voltage of the power output from the gas turbine and steam
turbine generators will be stepped up to 230kV via GT transformer and ST transformer. The output
from these two GT transformers and ST transformer is transmitted to the 230kV substation
respectively. The bus switching arrangement utilizes breaker and one half bus scheme.
During the unit operations, the power source to the unit auxiliary loads will be fed from the GTG
via the unit transformer. During the unit shut down and the unit start-up, the power source to the
unit auxiliary loads will be fed from 132kV substation via the start-up transformer. The unit
transformers shall be connected to the 6.9kV unit bus A via the circuit breakers. On the other
hand, the start-up transformer shall be connected to the 6.9kV unit bus B via the circuit breakers.
The power will be distributed to the auxiliary loads from the unit bus.
The auxiliary system and associated equipment shall be designed with flexibility and adequate
redundancy to provide a reliable source of power for all auxiliaries that will be required for the new
plant.
GT Generator is synchronized at 230kV power system via GT circuit breaker when GTG is
attained at rated speed and voltage. Next ST Generator is synchronized at 230kV power system
via ST circuit breaker when STG is attained at rated speed and voltage.
GTG and STG can be synchronized at 230kV power system breaker which is formed by one half
bus scheme. For that reason there is no need to introduce GT and ST circuit breakers. However
230kV substation shall be owned by PGCB. Also GTG and STG are synchronized by NWPGCL.
As a result GT and ST circuit breakers shall be set at power station side (2nd side of GT and ST
transformer) for synchronization by NWPGCL.
2)
Generator Main Circuit
Attached Single Line Diagram shows the Generator Main Circuit.
The design of generator main circuit shall be based on the multi shaft configuration of the having
two (2) generators (GTG and STG) and two (2) generator step-up transformers (GT transformer
and ST transformer). Each generator, transformer, PT is connected to Isolated Phase Bus (IPB)
and transmitted 230kV substation via each generator circuit breaker and generator disconnecting
switch.
(2)
Generators
1)
GT Generator and ST Generator
The overview specifications of the Generators are shown below.
Generator
Type
GT Generator
ST Generator
Three Phase
Synchronous
Three Phase
Synchronous
Number of Poles
2
2
3
3
Number of Phases
Rated Capacity
248M
VA
131.6MVA
Frequency
50Hz
50Hz
Rated Speed
3,000
rpm
3,000rpm
Terminal Voltage
16kV
11kV
0.80（Lagging）
Power Factor
Rotor Cooling Method
Stator
Method
Cooling
Hydrogen or Water
Cooled
Hydrogen or Water
Cooled
0.80（Lagging）
Hydrogen or
Water Cooled
Hydrogen or
Water Cooled
Figure 46. Overview Specifications of the Generators
2)
Type of Generator Cooling System
The generators for the gas turbine and the steam turbine shall be of air cooled or H2 gas cooled
type. The Bidder shall have the application experience with similar capacity to the generator
specified in his Bid. The generator manufacturer shall have the experience to have provided at
least two (2) air-cooled generators and/or two (2) H2 gas cooled generators, of which capacities
shall not be less than 280MVA on IEC conditions.
Either air-cooled or hydrogen gas-cooled system can adapt to the gas turbine generator and the
steam turbine generator.
3)
Comparison of Generator Cooling System Comparison of both cooling systems is as
follows;
As a result of recent technological advance of cooling performance and windage loss reduction,
an air-cooled system is adopted in generators of higher than 300MVA class.
An air-cooled system has some advance from hydrogen gas-cooled system such as; simpler
system, easy operation and maintenance, saving cost. On the other hand adoption of air-cooled
system make generator downsized so that air-cooled system has advantage for transportation
and construction stage.
Therefore, the generators for the gas turbine and the steam turbine shall be of air cooled or H2
gas cooled type. The Bidder shall have the application experience with similar capacity to the
generator specified in his Bid.
The generator manufacturer shall have the experience to have provided at least two (2) air-cooled
generators and / or two (2) H2 gas cooled generators, of which capacities shall not be less than
280MVA on IEC conditions.
Figure 47. Comparison of Cooling System
(3)
Excitation Method
1)
Excitation System
Each generator will be provided with thyristorised static excitation system which makes it possible
to provide full ceiling voltage, either positive or negative, almost instantaneously under conditions
of system disturbances. The system shall include transformer, automatic voltage regulator system
(hereinafter called as “AVR”) cubicle, thyristor, convertor cubicle and field circuit breaker. Current
transformer for control, regulation, protection and metering of the generator would be either
provided in the generator stator terminal bushing both on the lines as well as neutral sides, or
would be housed in IPB.
2)
Automatic Voltage Regulator System
The generator manufacturer shall have AVR. AVR detects generator voltage and control the
reactive power to control the generator voltage.
(4)
GT Start-up Method
Motor Driven Torque Converter and Thyristor Start-up Method
GT Start-up Method shall be Motor Driven Torque Converter or Thyristor Start-up Method. It
depends on contractor’s recommendation.
(5)
Transformers
Attached Single Line Diagram shows each transformer.
1)
GT Transformer
GT Transformer shall step up from GTG voltage (16kV) to transmission line voltage (230kV).
GT Transformer shall have tap changing mechanism, oil insulation three (3) phase transformer
or four (4) single phase transformer (One for spare). Cooling type shall be ONAF (Oil Natural Air
Forced). Phase connection shall be Δ-Y (Delta-Star) type.
2)
ST Transformer
ST Transformer shall step up from STG voltage (11kV) to transmission line voltage (230kV).
ST Transformer shall have tap changing mechanism, oil insulation three (3) phase transformer or
four (4) single phase transformer (One for spare). Cooling type shall be ONAF (Oil Natural Air
Forced). Phase connection shall be Δ-Y (Delta-Star) type.
3)
Unit Transformer
Unit Transformer shall step down from GTG voltage (16kV) to Unit Bus A (6.9kV).
Unit Transformer shall have tap changing mechanism, oil insulation three (3) phase transformer
or four (4) single phase transformer (One for spare). Cooling type shall be ONAN (Oil Natural Air
Natural). Phase connection shall be Δ-Y (Delta-Star) type.
4)
Start-up Transformer
Start-up Transformer shall step down from transmission line voltage (132kV) to Unit Bus B
(6.9kV).
Start-up Transformer shall be oil insulation three (3) phase transformer or four (4) single phase
transformer (One for spare). Cooling type shall be ONAN (Oil Natural Air Natural). Phase
connection shall be Y-Y-Δ (Star-Star-Delta with Stabilizing Winding) type. Y-Y-Δ connection
makes detection of grounding fault current easier.
The overview specifications of the Transformers are shown below.
Figure 48. Overview Specifications of the Transformers
(6)
Single Phase Transformer and Three Phase Transformer
In Comparison to Three Phase Transformer and Single Phase Transformer is shown in following
Table.
BPDB requested JICA TEAM to introduce Single Phase Transformer for this project. For sure
Single Phase Transformer has advantage in case of transportation or replacement of one phase
transformer by accident. On the other hand, Single Phase Transformer is more expensive
because of necessity of the spare transformer, control equipment for each transformer and each
basement. Three Phase Transformer and Single Phase Transformer are equal in performance
aspect.
Therefore Transformer Method shall be Three Phase Transformer or Single Phase Transformer
Method. It depends on contractor’s recommendation.
Figure 49. Three-Phase Transformer and Single-Phase Transformer
(7)
Generator Circuit Breaker and Disconnecting Switch
GT Circuit Breaker, Disconnecting Switch and ST Circuit Breaker, Disconnecting Switch are set
at 2nd side of GT and ST transformer for synchronization.
GT Generator is synchronized at 230kV power system via GT circuit breaker when GTG is
attained at rated speed and voltage. Next ST Generator is synchronized at 230kV power system
via ST circuit breaker when STG is attained at rated speed and voltage.
GT and STG can be synchronized at 230kV power system breaker which is formed by one half
bus scheme. For that reason there is no need to introduce GT and ST circuit breakers. However
230kV substation shall be owned by PGCB. Also GTG and STG are synchronized by NWPGCL.
As a result GT and ST circuit breakers shall be set at power station side for synchronization by
NWPGCL.
GT and ST circuit breakers shall adapt the load capacity. The normal specifications of the GT
and ST circuit breakers are shown below.
•
Rated Normal Current：800 – 1,250 A
•
Rated Short Circuit Breaking Current：25.0 – 31.5 kA
(8)
Unit Electric Supply
The unit electric supply shall be configured from unit transformer and start-up transformer. The
equipment used for power plant operation shall be powered from the unit transformer. The
equipment used for common equipment (water handling, waste water handling, etc) shall be
powered from the start-up transformer system.
Moreover, as electric power source for emergencies, 1 set of 3 phase diesel fueled generator is
installed for power plant and this enables obtaining safety electricity upon total cessation of the
operation of the power plant.
1)
6.9kV Unit Bus
6.9kV Unit Bus shall supply necessary auxiliary power for plant operation.
The design of generator main circuit shall be based on the two (2) configuration of A and B.
Unit Transformer shall step down from GTG voltage (16kV) to Unit Bus A (6.9kV) and Unit Bus
A shall supply necessary auxiliary power and 415kV Unit Bus.
Start-up Transformer shall step down from transmission line voltage (132kV) to Unit Bus B
(6.9kV) and Unit Bus B shall supply necessary auxiliary power.
Unit Bus A and B (6.9kV) are connected via bus-tie circuit breaker and disconnecting switch.
Basically the bus-tie circuit breaker and disconnecting switch are opened. The bus-tie circuit
breaker and disconnecting switch are closed at start-up and shutdown stage. Unit Bus B
evacuates Unit Bus A the electric power in that case. Also Unit Bus B evacuates Unit Bus A the
electric power when plant accidentally tripped.
2)
415kV Unit Bus
415kV Unit Bus shall supply medium motors and auxiliary power for switching.
3)
220V DC Electric Supply System
220V DC Electric Supply System shall have two (2) battery equipment and DC load shall be
supplied the power from DC distribution board. Plant can stop safely by DC power from battery
under blackout condition.
4)
Emergency Diesel Generator Equipment
Plant shall have one (1) Emergency Diesel Generator Equipment.
It shall be capable for restart-up of the plant by power from Emergency Diesel Generator
Equipment. Emergency AC power shall be supplied from Emergency Diesel Generator to 415kV
Emergency Bus.
BRAYTON CYCLE
In the Brayton cycle, high-pressure and high-temperature gaseous combustion products
enter directly a gas turbine, where part of their enthalpy is converted to shaft work. The
gas turbine drives a compressor and the electric power generator.
FORMULAS
SAMPLE EQUIPMENT DIMENSIONS
4.5 MW Gas Turbine
Dimensions
Base plate width
93 in (2.36 m)
Base plate length
281 in (7.14 m)
Enclosure height
94 in (2.39 m)
Base plate weight
60,000 lb (27,273 kg)
Duct flow areas
Inlet
12 ft2 (1.12 m2)
Exhaust
7 ft2 (0.65 m2)
Performance
Output
4,570 kW
Heat rate
8,140 Btu/shp-hr
10,916 Btu/kW-hr
11,520 kJ/kW-hr
Exhaust gas flow
16.3 kg/sec
Exhaust gas temperature
565°C
Power turbine speed
7000 rpm
52 MW Gas Turbine
Dimensions
Base plate width
Base plate length
169.6 in (4.31 m)
650 in (16.51 m)
Enclosure height
193.3 in (4.91 m)
Base plate weight
302,000 lb(136,985 kg)
Duct flow areas
Inlet
90 sqft(8.36 sqm)
Exhaust
57 sqft(5.3 sqm)
Performance
Output
52,403
Heat rate
6,117 Btu/shp-hr
8,210 Btu/kW-hr
8,660 kJ/kW-hr
Exhaust gas flow
141 kg/sec
Exhaust gas temperature
499°C
Power turbine speed
3930 rpm
PROBLEM SOLVING
1. The compressor inlet air temperature in a gas turbine plant is 99°C. Calculate the
compressor air exit temperature if it requires 400 kJ/kg of work.
2. There are required 2238 kW net from a gas turbine unit for pumping of crude oil from the
North Alaskan Slope. Air enters the compressor section at 99.975 kPa, 278 K, the
pressure ratio rp = 10. The turbine section receives the hot gases at 1111 K. Assume the
closed Brayton cycle and find thermal efficiency.
3. In a gas turbine unit, energy entering is 600 kJ/kg at 250 m/sec and a mass of 4 kg. Energy
leaving the turbine is 486 kJ/kg at 170 m/sec. Heat loss is 10 kJ. What is the turbine work?
Given:
ℎ3 = 600 𝑘𝐽/𝑘𝑔
ℎ4 = 486 𝑘𝐽/𝑘𝑔
𝑄𝐿 = 10 𝑘𝐽
𝑣3 = 250 𝑚/𝑠
𝑣4 = 170 𝑚/𝑠
𝑚 = 4 𝑘𝑔
Required:
𝑊𝑡
Solution:
1
𝑚 (𝑣32 − 𝑣42 ) − 𝑄𝐿
2
4 (2502 − 1702 )
𝑊𝑡 = 4(600 − 486) +
− 10
2 × 1000
𝑊𝑡 = 456 + 67.2 − 10
𝑊𝑡 = 513.2 𝑘𝐽
𝑊𝑡 = 𝑚(ℎ3 − ℎ4 ) +
W = 513 kJ
4. In a gas turbine unit, air enters the combustion chamber at 550 kPa, 227 °C and 43m/s.
The products of combustion leave the combustor at 511 kPa, 1004 °C and 10 m/s. Liquid
fuel enters with a heating value of 43, 000 kJ/kg. For fuel-air ratio of 0.0229, what is the
combustor efficiency of the unit in percent?
Given:
𝑡1 = 227 ℃
𝑡2 = 1004 ℃
𝑉1 = 43 𝑚/𝑠
𝑉2 = 140 𝑚/𝑠
𝑚𝑓 = 0.0229
𝑄𝑛 = 43000 𝑘𝐽/𝑘𝑔
Required:
Combustor Efficiency
Solution:
𝐶𝑜𝑚𝑏𝑢𝑠𝑡𝑜𝑟 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
𝐻𝑒𝑎𝑡 𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑
𝐻𝑒𝑎𝑡 𝑆𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑏𝑦 𝐹𝑢𝑒𝑙
𝐻𝑒𝑎𝑡 𝑆𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑏𝑦 𝐹𝑢𝑒𝑙 = 𝑚𝑓 × 𝑄𝑛 = 0.0229 × 43000 𝑘𝐽/𝑘𝑔
= 984.70 𝑘𝐽/𝑘𝑔 𝑎𝑖𝑟
1
𝐻𝑒𝑎𝑡 𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑 = 𝐶𝑝 (𝑡2 − 𝑡1 ) + (𝑉2 − 𝑉1 )
2
1 (140)2 − (43)2
𝐻𝑒𝑎𝑡 𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑 = 1 (1004 − 227) + (
)
2
1000
𝐻𝑒𝑎𝑡 𝐴𝑏𝑠𝑜𝑟𝑏𝑒𝑑 = 785.88 𝑘𝐽/𝑘𝑔 𝑎𝑖𝑟
785.88 𝑘𝐽/𝑘𝑔 𝑎𝑖𝑟
984.70 𝑘𝐽/𝑘𝑔 𝑎𝑖𝑟
𝑒𝑐 = 0.7981 𝑜𝑟 79.81%
𝑒𝑐 =
Combustor Efficiency = 79.81%
What is the efficiency of the compressor in a gas turbine plant if the compressor
power is 300kW. Power input is 400kW.
300𝑘𝑊
400𝑘𝑊
𝑒𝑐 = 0.75 𝑜𝑟 75%
𝑒𝑐 =
What is the thermal efficiency of an air-strained Brayton Cycle if the pressure
ratio is 10.
𝑒
1
= 1−
𝑟𝑝
𝑒
1.4−1
1.4
1
= 1−
10
𝑒 = 0.4821
Thus;
𝑒𝑡 = 48.21%
1.4−1
1.4
5. . The compressor for an actual gas turbine requires 450 KJ/kg of work to triple the inlet
pressure. The inlet air temperature is 105°C. Determine the compressor air exit
temperature in Celsius.
6. . An air standard Brayton cycle has a compression ratio 9.8.
Determine the engine efficiency.
7. . A power plant operates on an ideal Brayton cycle. The gas temperature at the turbine
inlet is 1400∘ 𝐾(1515.2 kJ/kg) and the gas temperature at the turbine exit is 800∘
𝐾(821.95 kJ/kg). Assume the turbine efficiency og 80%, what is the actual turbine work
in kJ/kg?
GIVEN:
𝑇3 = 1400∘ 𝐾
ℎ3 = 1515.2 kJ/kg
𝑇4 = 800∘ 𝐾
ℎ4 = 821.95 kJ/kg
REQUIRED: 𝑊𝑡𝑎 = ?
SOLUTION:
𝑊𝑡𝑎 = 𝑊𝑡 X 𝑒𝑡𝑢𝑟𝑏𝑖𝑛𝑒
Solving for 𝑊𝑡 ;
𝑊𝑡 = (ℎ3 - ℎ4 ), kJ/kg
= (1515.2-821.95),kJ/kg
= 693.25 kJ/kg
Thus;
𝑊𝑡𝑎 = 𝑊𝑡 X 𝑒𝑡𝑢𝑟𝑏𝑖𝑛𝑒
= 693.25 kJ/kg X 0.80
Final Answer:
𝑊𝑡𝑎 = 554.6 kJ/kg
8. . In a gas turbine plant, the mass flow rate is 6.2kg/s, the enthalpy at the combustor
entrance is 250 kJ/kg and the enthalpy at the exit is 980 kJ/kg. What is the capacity of the
combustor in kW?
GIVEN:
ℎ1 = 250 kJ/kg
ℎ2 = 980 kJ/kg
m = 6.2kg/s
REQUIRED:
Capacity of the combustor, 𝑄𝐴
SOLUTION:
Heat added in the combustor, 𝑄𝐴 = m(ℎ2 -ℎ1 )
= 6.2kg/s (980 kJ/kg - 250 kJ/kg)
Final Answer:
𝑄𝐴 = 4526 kW
9. The air standard Brayton cycle has a net power output of 200KW. Air entering the
compressor at 30°C, leaving the high temperature heat exchanger at 950°C and leaving
the turbine at 302°C. Determine the mass flow rate of air in kilogram per hour.
Given:
T1=30C
T3=950
T4=302
Wn=200 kW
Unknown:
m
Solution:
10. The compressor for an actual gas turbine requires 450KJ/kg of work to triple the inlet
pressure. The inlet air temperature is 105°C. Determine the engine efficiency if the mass
flow rate is 5kg/sec.
Solution:
11. The pressure ratio of a standard Brayton cycle is 9 and the maximum temperature in the
cycle is 1080 deg. C. Compute for the cycle efficiency per kg of air in percent?
Solution:
12. A gas turbine utilizing an air standard brayton cycle has a pressure ratio of 10. The air
inlet conditions are 100 Kpa and 27 deg C. The maximum allowable temperature is 1300
deg C. calculate the heat added in KJ/kg.
Given:
Solution:
13. An air standard Brayton cycle has air enter the compressor at 28°C and 100kpa. The
pressure ratio is 13 and the maximum allowable temperature in the cycle is 1450K.
Determine the heat added.
Solution:
14. Air at 5 bar and 590K is extracted from a jet engine compressor to be used for the
generation of auxiliary power for the cabin. The extracted air is cooled in a constant
pressure heat exchanger down to 450K. It then enters an isentropic turbine and expands
to 1 bar before being rejected into the cabin. If the mass flow is 10 kg/min, determine the
rate of heat transfer out of the constant pressure heat exchanger.
Solution:
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