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Combined Cycle Power Plant Combined Cycle Power Plant: Bydra Klilu T Esfamichael

A combined cycle power plant uses both a gas turbine and a steam turbine together to generate electricity. The gas turbine produces waste heat that is used to generate high-pressure steam in a heat recovery steam generator. This steam then powers a steam turbine which generates additional electricity. Combined cycle power plants can achieve thermal efficiencies between 50-60% or even higher up to 80-90% if the waste heat is also used for cogeneration/district heating purposes. The schematic shows the gas turbine exhaust heating water in the HRSG to make steam for the steam turbine, significantly improving overall efficiency over gas-only or steam-only plants.

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93 views15 pages

Combined Cycle Power Plant Combined Cycle Power Plant: Bydra Klilu T Esfamichael

A combined cycle power plant uses both a gas turbine and a steam turbine together to generate electricity. The gas turbine produces waste heat that is used to generate high-pressure steam in a heat recovery steam generator. This steam then powers a steam turbine which generates additional electricity. Combined cycle power plants can achieve thermal efficiencies between 50-60% or even higher up to 80-90% if the waste heat is also used for cogeneration/district heating purposes. The schematic shows the gas turbine exhaust heating water in the HRSG to make steam for the steam turbine, significantly improving overall efficiency over gas-only or steam-only plants.

Uploaded by

Shafir
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Combined cycle power plant

By Dr Aklilu
A klilu Tesfamichael
Combined Power Plants
A combine power plant is a system consists of a gas turbine power 
 plant ,Heat Recovery Steam Generator (HRSG), generators,
controls, and a steam turbine power plant.
The gas exit temperature should be above 120 C to prevent corrosion

Fig: combined power plant


More Ways to Increase Power plant Thermal
Efficiency
 A combined gas turbine based power plant is essentially an
electrical power plant in which a gas turbine and a steam
turbine are used in combination to achieve greater efficiency
than would be possible independently.

 Since the increase in power output occurs without the input of 
additional heat, the overall thermal efficiency is increased.
Combined power plant efficiency

Fig: Schematic of Combined Cycle (CCGT) power plant.

 Net  power  produced  
W  
W  W net , ST 
net  net ,GT 
total  (50 60%)
Qin
m
  f    LHV  m
  f    LHV 
Combined heat and power or cogeneration efficiency

 Industries often require both power and heating loads

 If the steam is used for heat (e.g. heating buildings,


industrial process) then the plant would be referred to as a
cogeneration plant or combined heat and power.

 Power   Heat  recovred  


W  net ,GT  Q HRSG
total  (80 90%)
Qin
m
  f    LHV 
Cooling load, as required by air conditioning and chilled
water systems, may also be served by cogeneration systems.

Absorption
chiller

Chilled
water 
Fig: Combined cooling and power 
Fig: Energy Flow in Traditional Supply
Fig: Energy flow of typical Combined cooling heating power plant
Heat Recovery Steam Generator (HRSG)

MTU-
Construction Phase: Heat Recovery Steam Generators

12/07/2
Construction Phase: Condenser

12/07/2
011
Combined Gas-Steam Power Plant

FIG: Combined gas –steam power plant.


Binary Vapor Cycles

FIG: Mercury –water binary vapor cycle.


Example
 A simple steam power plant operates between pressures of 10 kPa and
4 MPa with a maximum temperature of 400ºC. The power output from the
steam turbine is 100 MW. A gas turbine provides the energy to the boiler;
it accepts air at 100 kPa and 25ºC, has a pressure ratio of 5, and a maximum
temperature of 850ºC. The exhaust gases exit the boiler at 350 K.
Determine the thermal efficiency of the combined Brayton-Rankine cycle.
End
Thank you

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