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8/3/2019 Introduction to GT &CCPP
http://slidepdf.com/reader/full/introduction-to-gt-ccpp 1/84
IntroductionTo
GT & CCPP
8/3/2019 Introduction to GT &CCPP
http://slidepdf.com/reader/full/introduction-to-gt-ccpp 3/84
Simple Gas Turbine Plant
8/3/2019 Introduction to GT &CCPP
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Simple Gas Turbine Plant
8/3/2019 Introduction to GT &CCPP
http://slidepdf.com/reader/full/introduction-to-gt-ccpp 5/84
Thermodynamic Process
Compression
Constant pressure heat addition
Expansion
Constant pressure Heat Rejection
8/3/2019 Introduction to GT &CCPP
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BRAYTON CYCLE
P
RE
S
S
U
R
E
VOLUME
SUCK
BURN
SQUEEZE BLOW
8/3/2019 Introduction to GT &CCPP
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COMPRESSOR
VOLUME
BRAYTON CYCLE
P
R
E
S
S
UR
E
COMBUSTOR
TURBINE
8/3/2019 Introduction to GT &CCPP
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Brayton Cycle
8/3/2019 Introduction to GT &CCPP
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Brayton Cycle
Eff t f T bi Effi i &
8/3/2019 Introduction to GT &CCPP
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Effect of Turbine Efficiency & pressure
ratio on Thermal efficiency
8/3/2019 Introduction to GT &CCPP
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Effect of pressure ratio & Temperature
ratio on Efficiency
8/3/2019 Introduction to GT &CCPP
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Effect of Pressure ratio on Efficiency
8/3/2019 Introduction to GT &CCPP
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Energy Losses In Gas Turbine
8/3/2019 Introduction to GT &CCPP
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They are more compact
They can be started and take more
load quickly
They are simpler in design and
easy maintenance
Merits
8/3/2019 Introduction to GT &CCPP
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They consume less metal other materials for the same capacity
They cost less.
They require almost no water for cooling.
Man power is 25% of theconventional coal based plants.
Merits
8/3/2019 Introduction to GT &CCPP
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Land requirement is less than30%
Availability is as high as 90%
Low gestation period.
The pollution is less
Merits
8/3/2019 Introduction to GT &CCPP
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They have a low specific power
They have the lower efficiency at the
modern state of progress
They have a shorter service life
They are more sensitive to fuel
quality
Demerits
8/3/2019 Introduction to GT &CCPP
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High cost of spare parts
High fuel cost-very volatile in case of liquid fuel
High generation cost
Demerits
8/3/2019 Introduction to GT &CCPP
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Energy Losses CC Concept
8/3/2019 Introduction to GT &CCPP
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Gas turbine plus Unfired steam
generator
Gas turbine plus supplementary
fired steam generator
Gas turbine plus furnace fired
steam generator
8/3/2019 Introduction to GT &CCPP
http://slidepdf.com/reader/full/introduction-to-gt-ccpp 29/84
Supercharged furnace fired steam
generator plus gas turbine
Integrated coal Gasification and
combined cycle Power plant
Diesel engine based combined
cycle
8/3/2019 Introduction to GT &CCPP
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Generally steam pressures are limited
to 60 ata. And SH temperatures limited
to 420/480
Gas turbine output will be 60-75%
Steam turbine output 30-35%
Net plant heat rate is in the order of
2500-2800 Kcal/kwh
8/3/2019 Introduction to GT &CCPP
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The flue gas temperature isincreased to 940
Steam generation can be doubledthat of an Unfired waste heat
recovery boiler Steam turbine and gas turbine
will be sharing the output equally
Net plant heat rate is 2250-2500Kcal/kwh
8/3/2019 Introduction to GT &CCPP
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Majority of the fuel is fired in the
steam generator
70-85 % of the plant load can bemet by the steam turbines
Increase in thermal efficiency 4-5%
Heat rate in the order of 2300Kcal/Kwh
8/3/2019 Introduction to GT &CCPP
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• Plant heat rate is in the order of 2250-2500Kcal/kwh
• Heat transfer co efficients are
significantly improved
8/3/2019 Introduction to GT &CCPP
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•Single shaft system
•Multi shaft system
8/3/2019 Introduction to GT &CCPP
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Modifications -Basic Cycle
Increase in power output
Increase in combustion
turbine efficiency
8/3/2019 Introduction to GT &CCPP
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By increasing the mass flow
through the turbine
Recovering heat from the
waste gas Reducing compressor work
Increasing the averagetemperature of the heat source
8/3/2019 Introduction to GT &CCPP
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• Evaporative cooling cycle
• Recuperative cycle
• Intercooled cycle
• Humid air turbine cycle
• Steam Injected cycle
8/3/2019 Introduction to GT &CCPP
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• Reheat cycle
• Intercooled steam injectedcycle
•Intercooled reheat steaminjected cycle
•
Intercooled reheat chemicallyrecuperated cycle
8/3/2019 Introduction to GT &CCPP
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Radial Flow
8/3/2019 Introduction to GT &CCPP
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t if l
8/3/2019 Introduction to GT &CCPP
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centrifualcompressor
Have an appreciably shorter length, Since the
pressure ratio attainable in a single stage is
B=4.5.(High pressure ratio per stage) They are simpler in design and easy to
manufacture thus leads to lower cost.
Under all operating conditions, more reliable
in operation. Centrifugal compressor is rugged in
construction and is less susceptible to the effects
of deposits left on the flow passages by the air.
centrif alcompressor
8/3/2019 Introduction to GT &CCPP
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centrifualcompressor
They are less sensitive to the fouling of
the flow path Maintains good efficiency over a wide
range of operations. (Their efficiency drops
down less strongly in off rated-regimes.With a low volume discharge of air, acentrifugal compressor often turns out to bemore efficient, since the efficiency of an
axial compressor reduces substantially insuch cases owing to increasing lossesassociated with the low height of blading.)
8/3/2019 Introduction to GT &CCPP
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Axial Flow
8/3/2019 Introduction to GT &CCPP
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Axial Flow Compressor
8/3/2019 Introduction to GT &CCPP
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A high delivery, upto 430-450 kg/s or
even more.
The highest efficiency possible incompressor is 83-90%. A high compressor pressure ratio due
to many stages with low losses as required for gas-
turbine plants. Small transverse dimensions (Low
cross sectional area) even with a high delivery.
8/3/2019 Introduction to GT &CCPP
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Axial compressors are having alarge number of stages and hence asophisticated design and appreciable lengthsince pressure ratio of single stage does notexceed 1.25. Has narrower operating range for good
efficiency. Higher weight and higher cost. • Starting power can be high.
8/3/2019 Introduction to GT &CCPP
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Film Cooling
8/3/2019 Introduction to GT &CCPP
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1. Directionally solidified
2. Single crystal
3. Normal Casting
1
2 3