ME 258 PPP

ME 258
FALL 2012
• A steam turbine is a device
that extracts thermal
energy from pressurized
steam and uses it to do
mechanical work on a
rotating output shaft.
• Its modern manifestation
was invented by Sir Charles
Parsons in 1884 whose first
model was connected to a
dynamo that generated
7.5kw of electricity.
• The steam turbine is a
form of heat engine
that derives much of its
improvement in
efficiency through the
use of multiple stages in
the expansion of the
steam, which results in
a closer approach to the
ideal reversible process.
• Steam turbines are made in a variety of sizes
ranging from small <0.75 kW (1< hp) units
(rare) used as mechanical drives for pumps,
compressors and other shaft driven
equipment, to 1,500,000 kW (2,000,000 hp)
turbines used to generate electricity.
Thermodynamics of steam turbines
 Steam Turbine operates
on basic principles of
thermodynamics using
the parts of Rankin cycle.
 Superheated vapor enters
the turbine, after it
having exited the boiler at
high T and P.
 The high T/P steam is
converted into kinetic
energy using nozzle.
 Once the steam has
exited the nozzle it is
moving at high velocity
and sent to the blades of
turbine to create force
causing them to move.
 A generator or other such
device can be placed on
the shaft and energy can
now be stored or used.
Solar Steam Turbines
• The solar steam generated by these state of the
art commercial solar thermal power plants does
not exceed 380ºC(553k), which limits the
conversion efficiency of the steam turbine
connected downstream.
• This performance limitation can be overcome by
raising the operability temperature of the
receiver and thereby increasing the conversion
efficiencies of the thermodynamic cycle:
 In point-focusing system, precise solar
concentration can be achieved .
Direct Solar Steam generator
• Some solar company
like AREVA offers direct
solar steam for :
 Enhanced oil recovery
 Petrochemical refining
 Food processing and
Solar thermal power plant
 In order to reduce fossil fuel
consumption and carbon
dioxide (CO2) emissions,
promoting the utilization of
renewable energy and
improving the efficiency of
energy utilization are
 Solar thermal energy, the most
abundant renewable energy
source, has been used to
generate electric power
energy in limited regions
where solar radiation energy is
• A steam accumulator is
incorporated as a heat
storage device to store
surplus steam produced
during the day when
solar radiation is large
and to use the steam
when solar radiation is
low .
Solar steam turbine performance
 During start-up of the
power plant, it is assumed
that the steam generator
is first brought to full load
with the steam produced
being dumped to the
condenser via the steambypass system
 The steam-turbine is
then progressively
loaded, and the bypass
valves closed.
Thermal power and turbine loads for a
day with intermittent solar radiation.
Start-up and cool-down time
Turbine Internal Temperature
Medium Scale Solar thermal PP
 aperture area- 100,000m^2
Steam temperature - 543k
Volume of steam accumulator- 4000m^3
Minimum steam pressure - 0.98Mpa
Condenser outlet temperature – 306k
Turbine inlet temperature -1573k
Generator operating Temperature – 873k
Concentration ratio 26
Optical efficiency 77%
Adiabatic efficiency of turbine - 87.5%
Adiabatic efficiency of compressor – 85%
Generator efficiency 98%
Annual total horizontal solar radiation energy
 Maximum net work output 12.4-22.4MW
 Net generated power 81-149Gwh/yr
[1].Economic evaluation of solar thermal hybrid H2O turbine power generation systems Takanobu Kosugi a,
Pyong Sik Pak b a Systems Analysis Group, Research Institute of Innovative Technology for the Earth, 9-2
Kizugawadai , Kizu-cho , Soraku-gun, Kyoto 619-0292 Japan
[2] Annual performance improvement for solar steam turbines throughnmthe use of temperaturemaintaining modifications James Spelling a,⇑, Markus Jo¨cker b, Andrew Martin a Department of Energy
Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
b Siemens Industrial Turbomachinery AB, SE-612 83 Finspa˚ ng, Sweden
[2] Lior N. Solar energy and the steam rankine cycle for driving and assisting heat pumps in heating and
cooling modes. Energy Conversion 1977;16(3):111–23.
[3] Pilkington Solar International. Status report on solar thermal power plants. Cologne: Pilkington Solar
International, 1996.
[4] Control concepts for direct steam generation in parabolic troughs
Loreto Valenzuela a,*, Eduardo Zarza a, Manuel Berenguel b,
Eduardo F. Camacho c a CIEMAT, Plataforma Solar de Almerıa, P.O. Box 22, Tabernas (Almerıa) E 04200,
[5] Birnbaum, J., Eck, M., et al., 2008. A direct steam generation solar power
plant with integrated thermal storage. In: Proceedings of the 14th Bienial Solar PACES Symposium. Las
Vegas, USA.
[6]Trough integration into power plants—a study on the performance and economy of integrated solar
combined cycle systems

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