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SNIST (JNTUH) – M.Tech (Therm.Engg)SNIST (JNTUH) – M.Tech (Therm.Engg)
GAS TURBINE POWER PLANTGAS TURBINE POWER PLANT
Dr. ...
Syllabus: GAS TURBINE PLANT
Cogeneration. Combined cycle power
plant, Analysis, Waste heat recovery,
IGCC power plant, Flu...
INTRODUCTION
 Gas turbines have been used for electricity generation in the
periods of peak electricity demand
 Gas turb...
GAS TURBINE
 The Thermal efficiency of the gas turbine is 20 to 30% compared with the
modern steam power plant 38 to 40%....
GAS TURBINE
 Gas turbine plant is defined as “ in which the principle of the prime mover
is of the turbine type and the w...
GAS TURBINE POWER PLANTS CLASSIFICATION
1.By Application: Jet Propulsion
 Air craft Prop-Jets
Peak Load Unit
Stand by Uni...
GAS TURBINE POWER PLANTS CLASSIFICATION
3.According to Arrangement:
 Simple
 Single Shaft
 Multi Shaft
 Inter cooled
...
Advantages of Gas Turbine Power Plants over Diesel Plants
 Work developed per kg of air is more than diesel plant
 Less ...
Disadvantages of Gas Turbine Power Plants over Diesel Plants
 Poor part load efficiency
 Special metals and alloys are r...
Advantages of Gas Turbine Power Plants over Steam Plants
 No ash handling
 Low capital cost and running costs
 Space re...
Working Principle of Gas Turbine
 Air is compressed(squeezed) to high pressure by a compressor.
 Then fuel and compresse...
Simple Gas Turbine
November 5, 201716
Gas turbine power plant
Air compressor:
 The air compressor and turbine are mounted at
either end on a...
November 5, 201717
Gas turbine power plant
Combustion chamber:
 In the combustion chamber, the compressed air
combines wi...
November 5, 201718
Gas turbine power plant
Turbine:
 Hot gases move through a multistage gas
turbine.
 Like in steam tur...
TYPES OF GAS TURBINE POWER PLANTS
The gas turbine power plants can be classified mainly
into two categories. These are :op...
OPEN CYCLE GAS TURBINE POWER
PLANTAND ITS CHARACTERISTICS
Gas turbines usually operate on an open
cycle
Air at ambient con...
November 5, 201721
Closed cycle gas turbine power plant
CLOSED CYCLE GAS TURBINE POWER PLANT
AND ITS CHARACTERISTICS
 The compression and
expansion processes remain
the same, bu...
Merits and Demerits of Closed Loop Cycle
Turbine over Open Loop Cycle turbine
 Merits:
 Higher thermal efficiency
 Redu...
Waste Heat Recovery
 To improve the efficiency and
economic feasibility using Waste Heat
Recovery System
Economizer/Fine Tube Heat Exchaner
Economizer…
Recuperator
 Recover exhaust gas waste heat in medium to
high temperature applications such as soaking
or annealing ovens...
Recupertors
 Heat exchange between
flue gases and the air
through metallic/ceramic
walls
 Ducts/tubes carry
combustion a...
Regenerator
 The exhaust gasses
from the turbine carry a
large quantity of heat
with them since their
temperature is far
...
Regenerator
 Large capacities
 Glass and steel melting
 furnaces
 Time between the
reversals important to
reduce costs...
Heat Wheels
 Porous disk rotating
between two side-byside
ducts
 Low to medium
temperature waste heat
recovery systems
...
Heat Pipe
 Transfer up to 100
times more thermal
energy than copper
 Three elements:
- sealed container
- capillary wick...
Heat Pipe – Performance &
Advantages
 Lightweight and compact
 No need for mechanical maintenance, input
power, cooling ...
Intercooler
 A compressor utilizes
the major percentage of
power developed by the
gas turbine.
 The work required by the...
Reheater
 The output of gas
turbine can be
improved by
expanding the gasses
in two stages with a
reheater between the
two...
Cogeneration
Combination of Gas Turbine Cycles
Gas Turbine and Steam Power Plants:
The combination of gas-turbine-steam cycle aims
at u...
Heating feed water with exhaust gases.
 The output heat of the gas
turbine flue gas is utilized to
generate steam by pass...
Employing the gases from a supercharged
boiler to expand in the gas turbine.
 The boiler furnace works under a
pressure o...
Employing the gases as combustion air in the
steam boiler.
 Exhaust gases are
used as preheated air
for combustion in the...
Combined Gas Turbine and Diesel Power
Plants
 The performance of
diesel engine can be
improved by
combining it with
exhau...
Turbo Charging / Supercharging
 This method is known as
supercharging.
 The exhaust of the diesel
engine is expanded in ...
Gas Generator
 The compressor which
supplies the compressed
air to the diesel engine is
not driven from gas
turbine but f...
Compound Engine
 The air compressor is
driven from both
diesel engine and gas
turbine through a
suitable gearing and
powe...
Integrated Gasification Combined Cycle (IGCC)
 Integrated Gasification Combined Cycle (IGCC) is
emerging as a best availa...
Basic Structure of IGCC
Air
N2
Critical Factors for Selection of IGCC
 IGCC is a capital-intensive technology.
 Therefore, to exploit with maximum prof...
How does IGCC work?
 IGCC is a combination of two leading technologies.
 The first technology is called coal gasificatio...
Coal Gasification
 As early as 1800, coal gas was made by heating coal in the absence of
air.
 Coal gas is rich in CH4
a...
 The exothermic reactions between coal and oxygen to produce CO
and CO2
provide enough energy to drive the reaction betwe...
c
Fluidised Bed Combustion
Advantages
Advantages…
Advantages…
ENDEND
GAS TURBINE POWER PLANT - SNIST
GAS TURBINE POWER PLANT - SNIST
GAS TURBINE POWER PLANT - SNIST
GAS TURBINE POWER PLANT - SNIST
GAS TURBINE POWER PLANT - SNIST
GAS TURBINE POWER PLANT - SNIST
GAS TURBINE POWER PLANT - SNIST
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GAS TURBINE POWER PLANT - SNIST

M.Tech (Thermal Engg) - SNIST (JNTUH)

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GAS TURBINE POWER PLANT - SNIST

  1. 1. SNIST (JNTUH) – M.Tech (Therm.Engg)SNIST (JNTUH) – M.Tech (Therm.Engg) GAS TURBINE POWER PLANTGAS TURBINE POWER PLANT Dr. VIJAYA BHASKAR SIRIVELLA Professor in Mechanical Engineering Sreenidhi Inst. of Sci. & Tech., Hyderabad
  2. 2. Syllabus: GAS TURBINE PLANT Cogeneration. Combined cycle power plant, Analysis, Waste heat recovery, IGCC power plant, Fluidized bed combustion, Advantages, Disadvantages
  3. 3. INTRODUCTION  Gas turbines have been used for electricity generation in the periods of peak electricity demand  Gas turbines can be started and stopped quickly enabling them to be brought into service as required to meet energy demand peaks.  Small unit sizes and their low thermal efficiency restricted the opportunities for their wider use for electricity generation.
  4. 4. GAS TURBINE  The Thermal efficiency of the gas turbine is 20 to 30% compared with the modern steam power plant 38 to 40%.  In future it is possible to construct efficiencies in and around 45%.  Following are the fields of Gas Turbine applications: Power Generation Aviation Oil and Gas industry Marine Propulsion  A Gas Turbine is used in aviation and marine fields because it is self contained, light weight not requiring cooling water and fit into the overall shape of the structure.  It is selected for the power generation because of its simplicity, lack of cooling water, needs quick installation and quick starting.  It is used in oil and gas industry because of cheap supply of fuel and low installation cost.  Limitations of the gas turbine: 1. They are not self starting 2. low efficiencies at part loads 3. non reversibility 4. Higher rotor speeds 5. Low overall plant efficiency.
  5. 5. GAS TURBINE  Gas turbine plant is defined as “ in which the principle of the prime mover is of the turbine type and the working medium is a permanent gas”.  Simple gas turbine plant consists of  Turbine  Compressor  Combustor  Auxiliary devices like starting device, lubricating pump, fuel pump, oil system and duct system.  The working fluid is compressed in a compressor which is generally rotary, multistage type.  Heat is added to the compressed fluid in the combustion chamber .  This high energy fluid at high temperature and pressure then expands in the turbine thereby generating power.  Part of the energy generated is consumed in driving the compressor and accessories and the rest is utilized in electrical energy.
  6. 6. GAS TURBINE POWER PLANTS CLASSIFICATION 1.By Application: Jet Propulsion  Air craft Prop-Jets Peak Load Unit Stand by Unit  Stationary End of Transmission Line Unit Base Load Unit Industrial Unit  Locomotive  Marine  Transport 2.By Cycle:  Open  Closed  Semi closed
  7. 7. GAS TURBINE POWER PLANTS CLASSIFICATION 3.According to Arrangement:  Simple  Single Shaft  Multi Shaft  Inter cooled  Reheat  Regenerative  Combination 4.According to combustion:  Continuous combustion  Intermittent combustion 5.By Fuel:  Solid fuel  Liquid fuel  Gaseous fuel
  8. 8. Advantages of Gas Turbine Power Plants over Diesel Plants  Work developed per kg of air is more than diesel plant  Less vibrations due to perfect balancing and no reciprocating parts  Less space requirements  Capital cost is less  Higher mechanical efficiency  Running speed of the turbine is large  Lower installation and maintenance costs  Torque characteristics of turbine plants are better than diesel plant  Ignition and lubrication systems are simpler  Specific Fuel Consumption (SFC) does not increase with time in gas turbine plant as rapidly in diesel plants  Poor quality fuel can be used  Light weigh with reference to Weight to power ratio is less for gas turbine power plants  Smoke less combustion is achieved in gas power plants
  9. 9. Disadvantages of Gas Turbine Power Plants over Diesel Plants  Poor part load efficiency  Special metals and alloys are required for different components  Special cooling methods required for cooling of turbine blades  Short life  Thermal efficiency is low  Wide operating speeds the fuel control is difficult  Needs to have speed reduction devices for higher operating speeds of turbine.  Difficult to start a gas turbine compared to diesel engine  Manufacturing of blades is difficult and costly  Same output gas turbines produces the five times the exhaust gases than IC engines.
  10. 10. Advantages of Gas Turbine Power Plants over Steam Plants  No ash handling  Low capital cost and running costs  Space requirement is less  Fewer auxiliaries are used  Can be built relatively quicker  Can brought on load quickly to support peak loads  Thermal efficiency of the gas turbine is higher than steam when working on top temperature (>5500 C)  Gas turbine plants quite economical for short running hours  Storage of fuel is smaller and handling is easy.  Less cooling water required for gas turbine plants compared to steam  Weight per H.P. is far less  Can be installed any where  Control of gas turbine is much easier.
  11. 11. Working Principle of Gas Turbine  Air is compressed(squeezed) to high pressure by a compressor.  Then fuel and compressed air are mixed in a combustion chamber and ignited.  Hot gases are given off, which spin the turbine wheels.  Gas turbines burn fuels such as oil, natural gas and pulverized(powdered) coal.  Gas turbines have three main parts: i) Air compressor ii) Combustion chamber iii) Turbine
  12. 12. Simple Gas Turbine
  13. 13. November 5, 201716 Gas turbine power plant Air compressor:  The air compressor and turbine are mounted at either end on a common shaft, with the combustion chamber between them.  Gas turbines are not self starting. A starting motor is used.  The air compressor sucks in air and compresses it, thereby increasing its pressure.
  14. 14. November 5, 201717 Gas turbine power plant Combustion chamber:  In the combustion chamber, the compressed air combines with fuel and the resulting mixture is burnt.  The greater the pressure of air, the better the fuel air mixture burns.  Modern gas turbines usually use liquid fuel, but they may also use gaseous fuel, natural gas or gas produced artificially by gasification of a solid fuel.
  15. 15. November 5, 201718 Gas turbine power plant Turbine:  Hot gases move through a multistage gas turbine.  Like in steam turbine, the gas turbine also has stationary and moving blades.  The stationary blades  guide the moving gases to the rotor blades  adjust its velocity.  The shaft of the turbine is coupled to a generator.
  16. 16. TYPES OF GAS TURBINE POWER PLANTS The gas turbine power plants can be classified mainly into two categories. These are :open cycle gas turbine power plant and closed cycle gas turbine power plant. Open Cycle Gas Turbine Power Plant In this type of plant the atmospheric air is charged into the combustor through a compressor and the exhaust of the turbine also discharge to the atmosphere. Closed Cycle Gas Turbine Power Plant In this type of power plant, the mass of air is constant or another suitable gas used as working medium, circulates through the cycle over and over again.
  17. 17. OPEN CYCLE GAS TURBINE POWER PLANTAND ITS CHARACTERISTICS Gas turbines usually operate on an open cycle Air at ambient conditions is drawn into the compressor, where its temperature and pressure are raised. The high pressure air proceeds into the combustion chamber, where the fuel is burned at constant pressure. The high-temperature gases then enter the turbine where they expand to atmospheric pressure while producing power output. Some of the output power is used to drive the compressor. The exhaust gases leaving the turbine are thrown out (not re-circulated), causing the cycle to be classified as an open cycle
  18. 18. November 5, 201721 Closed cycle gas turbine power plant
  19. 19. CLOSED CYCLE GAS TURBINE POWER PLANT AND ITS CHARACTERISTICS  The compression and expansion processes remain the same, but the combustion process is replaced by a constant-pressure heat addition process from an external source.  The exhaust process is replaced by a constant- pressure heat rejection process to the ambient air.
  20. 20. Merits and Demerits of Closed Loop Cycle Turbine over Open Loop Cycle turbine  Merits:  Higher thermal efficiency  Reduced size  No contamination  Improved heat transmission  Lesser Fluid friction  No loss in working medium  Greater output  Inexpensive fuel.  Demerits:  Complexity  Large amount of cooling water is required.  Dependent System  Not economical for moving vehicles as weight /kW developed is high.  Requires the use of very large air heater.
  21. 21. Waste Heat Recovery  To improve the efficiency and economic feasibility using Waste Heat Recovery System
  22. 22. Economizer/Fine Tube Heat Exchaner
  23. 23. Economizer…
  24. 24. Recuperator  Recover exhaust gas waste heat in medium to high temperature applications such as soaking or annealing ovens, melting furnaces, afterburners, gas incinerators, radiant tube burners, and reheat furnaces.  Recuperators can be based on radiation, convection, or combinations  Recuperators are constructed out of either metallic or ceramic materials.
  25. 25. Recupertors  Heat exchange between flue gases and the air through metallic/ceramic walls  Ducts/tubes carry combustion air for preheating  Waste heat stream on other side
  26. 26. Regenerator  The exhaust gasses from the turbine carry a large quantity of heat with them since their temperature is far above the ambient temperature.  They can be used to heat air coming from the compressor there by reducing the mass of fuel supplied in the combustion chamber.
  27. 27. Regenerator  Large capacities  Glass and steel melting  furnaces  Time between the reversals important to reduce costs  Heat transfer in old regenerators reduced by  Dust & slagging on surfaces  heat losses from the walls
  28. 28. Heat Wheels  Porous disk rotating between two side-byside ducts  Low to medium temperature waste heat recovery systems  Heat transfer efficiency up to 85 %
  29. 29. Heat Pipe  Transfer up to 100 times more thermal energy than copper  Three elements: - sealed container - capillary wick structure - working fluid  Works with evaporation and condensation
  30. 30. Heat Pipe – Performance & Advantages  Lightweight and compact  No need for mechanical maintenance, input power, cooling water and lubrication systems  Lowers the fan horsepower requirement and increases the overall thermal efficiency of the system  Can operate at 315 ◦C with 60% to 80% heat recovery
  31. 31. Intercooler  A compressor utilizes the major percentage of power developed by the gas turbine.  The work required by the compressor can be reduced by compressing the air in two stages and incorporation a intercooler between the two.
  32. 32. Reheater  The output of gas turbine can be improved by expanding the gasses in two stages with a reheater between the two.  The H.P. turbine drives the compressor and the LP turbine provides useful power output.
  33. 33. Cogeneration
  34. 34. Combination of Gas Turbine Cycles Gas Turbine and Steam Power Plants: The combination of gas-turbine-steam cycle aims at utilizing the heat of exhaust gases from the gas turbine thus, improve the overall plant efficiency. The popular designs are:  1. Heating feed water with exhaust gases.  2. Employing the gases from a supercharged boiler to expand in the gas turbine.  3. Employing the gasses as combustion air in the steam boiler.
  35. 35. Heating feed water with exhaust gases.  The output heat of the gas turbine flue gas is utilized to generate steam by passing it through a heat recovery steam generator (HRSG), so it can be used as input heat to the steam turbine power plant.  This combination of two power generation cycles enhances the efficiency of the plant.  While the electrical efficiency of a simple cycle plant power plant without waste heat utilization typically ranges between 25% and 40%, a CCPP can achieve electrical efficiencies of 60% and more.
  36. 36. Employing the gases from a supercharged boiler to expand in the gas turbine.  The boiler furnace works under a pressure of about 5 bars and the gases are expanded in the gas turbine, the exhaust being used to heat feed water before being discharged through the stack.  The heat transfer rate is very high as compared to conventional boiler due to high pressure of gases, and smaller size of steam generator is needed.  No need of forced draught fans as the gases in furnace are already under pressure.  Overall improvement in heat rate is 7%.
  37. 37. Employing the gases as combustion air in the steam boiler.  Exhaust gases are used as preheated air for combustion in the boiler, results in 5% improvement in heat rate. The boiler is fed with supplementary fuel and air, and is made larger than conventional furnace.
  38. 38. Combined Gas Turbine and Diesel Power Plants  The performance of diesel engine can be improved by combining it with exhaust driven gas turbine.  Three combinations: 1. Turbo charging 2. Gas Generator 3. Compound engine
  39. 39. Turbo Charging / Supercharging  This method is known as supercharging.  The exhaust of the diesel engine is expanded in the gas turbine and the work output of the gas turbine is utilized to run a compressor which supplies the pressurized air to the diesel engine to increase its output.
  40. 40. Gas Generator  The compressor which supplies the compressed air to the diesel engine is not driven from gas turbine but from the diesel engine through some suitable device.  The output of diesel engine is consumed in driving the air compressor and gas turbine supplies the power.
  41. 41. Compound Engine  The air compressor is driven from both diesel engine and gas turbine through a suitable gearing and power output is taken from the diesel engine shaft.
  42. 42. Integrated Gasification Combined Cycle (IGCC)  Integrated Gasification Combined Cycle (IGCC) is emerging as a best available technology to utilize low quality or contaminated energy resources, coal or oil.  It can meet emission limits not achievable by other conventional or advanced competing technologies.  In particular IGCC offers refiners the possibility of reducing to zero the production of residual fuel oil, an increasingly undesired product, while at the same time, co-producing electricity, hydrogen and steam.  It also drastically cuts SO2 emissions.
  43. 43. Basic Structure of IGCC Air N2
  44. 44. Critical Factors for Selection of IGCC  IGCC is a capital-intensive technology.  Therefore, to exploit with maximum profit all the advantages of this technology, it is important to optimize the design to improve performance and reduce capital cost.  One important design aspect is the degree of integration between the gas turbine and the air separation unit.  The choice of the optimum degree of integration can bring substantial benefits in performance efficiency and capital outlay.  The selection of the best degree of integration to assure the maximum profitability of IGCC.  The need of clean energy technologies has been in existence since the first oil crisis more than 25 years ago.  IGCC is emerging today as one of the most promising technologies to exploit low-quality solid and liquid fuels and meet the most stringent emission limits.
  45. 45. How does IGCC work?  IGCC is a combination of two leading technologies.  The first technology is called coal gasification, which uses coal to create a clean-burning gas (syngas).  The second technology is called combined-cycle, which is the most efficient method of producing electricity commercially available today.  Coal Gasification:  The gasification portion of the IGCC plant produces a clean coal gas (syngas) which fuels the combustion turbine.  Coal is combined with oxygen in the gasifier to produce the gaseous fuel, mainly hydrogen and carbon monoxide.  The gas is then cleaned by a gas cleanup process.  After cleaning, the coal gas is used in the combustion turbine to produce electricity.
  46. 46. Coal Gasification  As early as 1800, coal gas was made by heating coal in the absence of air.  Coal gas is rich in CH4 and gives off up to 20.5 kJ per liter of gas burned.  Coal gas or town gas, as it was also known became so popular that most major cities and many small towns had a local gas house in which it was generated, and gas burners were adjusted to burn a fuel that produced 20.5 kJ/L.  A slightly less efficient fuel known as water gas can be made by reacting the carbon in coal with steam.  C(s) + H2 O(g) → CO(g) + H2 (g) ( Ho = 131.3 kJ/molrxn )  Water gas burns to give CO2 and H2 O, releasing roughly 11.2 kJ per liter of gas consumed.  Note that the enthalpy of reaction for the preparation of water gas is positive, which means that this reaction is endothermic.  As a result, the preparation of water gas typically involves alternating blasts of steam and either air or oxygen through a bed of white-hot coal.
  47. 47.  The exothermic reactions between coal and oxygen to produce CO and CO2 provide enough energy to drive the reaction between steam and coal.  Water gas formed by the reaction of coal with oxygen and steam is a mixture of CO, CO2 , and H2 . The ratio of H2 to CO can be increased by adding water to this mixture, to take advantage of a reaction known as the water-gas shift reaction.  CO(g) + H2 O(g) → CO2 (g) + H2 (g) Ho = -41.2 kJ/molrxn  The concentration of CO2 can be decreased by reacting the CO2 with coal at high temperatures to form CO.  C(s) + CO2 (g) → 2 CO(g) Ho = 172.5 kJ/molrxn  Water gas from which the CO2 has been removed is called synthesis gas.  Synthesis gas can also be used to produce methane, or synthetic natural gas (SNG).  CO(g) + 3 H2 (g) → CH4 (g) + H2 O(g)  2 CO(g) + 2 H2 (g) → CH4 (g) + CO2 (g)
  48. 48. c
  49. 49. Fluidised Bed Combustion
  50. 50. Advantages
  51. 51. Advantages…
  52. 52. Advantages… ENDEND

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