THERMAL POWER CYCLES AND THEIR

APPSPowerPoint Presentation by:

PRATEEK SHARMAME-V A

1313340114

NOIDA INSTITUTE OF ENGINEERING AND TECHNOLOGY

ELECTRICITY… how it is produced?

THERMAL POWER PLANT CYCLE

RANKINE CYCLE

PROCESSES INVOLVED…. Process (1-2): isentropic compression Process (2-3): constant pressure heat

addition Process (3-4): isentropic expansion Process (4-1): constant pressure heat

rejection

MODIFICATIONS IN RANKINE CYCLE - Reheat cycle

Regenerative cycle

MODIFICATIONS IN RANKINE CYCLE - Combined Cycle

ORGANIC RANKINE CYCLE

The Organic Rankine cycle (ORC) is named for its use of an organic, high molecular mass fluid with a liquid-vapor phase change, orboiling point, occurring at a lower temperature than the water-steam phase change. The fluid allows Rankine cycle heat recovery from lower temperature sources such as biomass combustion, industrial waste heat, geothermal heat, solar ponds etc. The low-temperature heat is converted into useful work, that can itself be converted into electricity. A prototype was first developed and exhibited in 1961 by solar engineers Harry Zvi Tabor and Lucien Bronicki

ORGANIC RANKINE CYCLE

WORKING PRINCIPLE OF ORC

The working principle of the organic Rankine cycle is the same as that of the Rankine cycle: the working fluid is pumped to a boiler where it is evaporated, passed through an expansion device (turbine or other expander), and then through a condenser heat exchanger where it is finally re-condensed.

LOSS IN EFFICIENCY In any real cycle, the presence of irreversibilities lowers the

cycle efficiency. Those irreversibilities mainly occur: During the expansion: Only a part of the energy recoverable

from the pressure difference is transformed into useful work. The other part is converted into heat and is lost. The efficiency of the expander is defined by comparison with an isentropic expansion.

In the heat exchangers: The working fluid takes a long and sinuous path which ensures good heat exchange but causes pressure drops that lower the amount of power recoverable from the cycle. Likewise, the temperature difference between the heat source/sink and the working fluid generates exergy destruction and reduces the cycle performance.

WHY USE ORC??? The use of organic fluid helps in more

efficient heat recovery from lower temperature sources because the boiling point of organic fluid used is lower than that of water so less energy will be required and organic fluids does not cause any corrosion in turbines.

FLUIDS USED IN ORC:Disadvantages of water probably to correct using other

working fluids, The ORC uses organic substances instead of water as working fluid :

Organic Rankine Cycle working fluids are: Toluene Butane Pentane Ammonia Refrigeration fluids Silicone oils

ADVANTAGES OF ORC:THECNICAL : High cycle efficiency Very high turbine efficiency Low turbine mechanical

stress due to low peripheral speed

Low turbine rpm, allowing the direct drive of the electric generator without gear reduction in many applications

No erosion of blades, thanks to the absence of moisture in the vapor nozzles

OPERATIONAL: Simple start-stop

procedures Automatic and continuous

operation No operator attendance

needed Quiet operation High availability (typically

98%) High efficiency at partial

load Lower maintenance cost Long life

ORC units

Applications:

Solar Energy

•Concentrating solar power systems with ORC units allow conversion of heat harnessed by solar collectors into electricity through an efficient thermodynamic cycle.

Biomass •simple and efficient generation of electric power and heat from biomass

Geothermal •electricity from geothermal resources with medium-to-low-temperatures, generally ranging between (90° C - 180° C).

Waste heat •by recovering heat from sources such as industrial processes,

ORC unit

GEOTHERMAL POWER PLANT Geothermal energy is thermal energy generated and stored

in the Earth.  The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials. This energy is used as a source of heating the organic fluid in power plant. Hence it is termed as Geothermal Power Plant.

COAL BASED POWER PLANT National Thermal Power Corporation

Limited (NTPC) is a typical example of coal based power plant which works on Rankine cycle.

It is the largest power company in India with an electric power generating capacity of 43,803 MW .

NTPC Dadri- capacity 1820 MW

RANKINE CYCLE:Advantages: cheap, widely available non toxic high heat capacity: excellent medium for heat transport chemical stable: less material requirements low viscosity: low friction lossesDisadvantages: due to low condensation t°: very low pressure, high specific

volume, big installations needed (turbine, condenser ) high pressure drop to become a high enthalpy drop: expensive

multi stage turbines needed expansion has to start in the superheated area to avoid too high

moisture content after expansion: need of a high t°- heat source but very practically use because of this: efficiency loss and limited suitability to waste heat recovery

THANK YOU….