THERMAL POWER STATION

Thermal Power StationA thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle.

1Types of thermal power stationThe greatest variation in the design of thermal power stations is due to the different fossil fuel resources generally used to heat the water.Three types of thermal power plants:fossil-fuel power plants: Power plants burning coal, fuel oil, or natural gasBiomass-fueled thermal power plantsConventional power plants: Non-nuclear thermal power plants, particularly fossil-fueled plants, which do not use co-generation.

2Advantages of Coal as Power Plant FuelReliability: Coals ability to supply power during peak power demand either as base power or as off-peak powerAffordability: Energy produced from coal fired plants is cheaper and more affordable than other energy sourcesAbundance: There are approximately over 300 years of economic coal deposits still accessible.Known technologies: The technology required in producing it is constantly advancingSafety: Generally, coal fired plants are considered safer than nuclear power plants.

3Disadvantages of Coal as Power Plant FuelGreenhouse gas emissions: it cannot be denied that coal leaves behind harmful byproducts upon combustion.Mining destruction: Mining of coal not only results in the destruction of habitat and scenery.Generation of millions of tons of waste: Millions of tons of waste products which can no longer be reused are generated from coal fired plants. Emission of harmful substances: Thermal plants like coal fired plants emit harmful substances to the environment.

4The biggest problem of thermal power stationsGlobally, fossil fueled thermal power plants produce a large part of man-made CO2 emissions to the atmosphere.Aboos thermal power station (Aboo, Asturias) -7.602.693 tons of CO2 annualy (the same as 2,5 millions of cars annually).

5As Pontes thermal power station(As Pontes de Garca Rodriguez, A Corua) -9.121.027 tons of CO2 annualy (the same as 3 millions of cars annually).Almeras (Carboneras, Almera) -6.998.752 tons of CO2 annualy (the same as 2,3 millions of cars annually).

The biggest problem of thermal power stations6Rankine Cycle: Description.-Idealized Thermodynamics cycle: HEAT MECHANICAL WORKELECTRICAL ENERGY

-Heat sources: - Nuclear fission - Combustion of fossil fuels (coal, natural gas, oil)

-Efficency of the cycle: depend on the heat of vaporization of the working fluid.

Carnot efficency .

Rankine Cycle : Process.

1-2 isentropic pump 2-3 constant pressure heat addition3-4 isentropic turbine 4-1 constant pressure heat rejectionRankine Cycle : Efficency.Equations:Carnot cycle efficency:Real Thermal power station.Nuclear thermal power station in Bavaria, Germany.Geothermal power station in Iceland.Taichung Thermal Power station, the worlds largest coal-fired power station, in Taiwan.

Real Thermal power station.

Elemental parts of a power plantBoilerBoilerEconomizerAir pre-heater

Steam turbinesHigh PressureMedium PressureLow Pressure

Cooling systemRiverCooling tower

BoilerCoal combustionWater SteamHigh pressure and temperature

Hot exhaust gases circuit:BoilerEconomizerAir pre-heater

Small industrial boiler

Power plant boiler

Real boiler in Dakota Power PlantEconomizerCold Feed Water Hot Feed Water

Less coal in the furnace

Higher efficiency (Less heat to the environment)

Air preheaterIncreases the temperature of the air supplied for coal burning

Air circuit:AtmosphereHuge fanAir preheaterBoiler

Advantages:Higher Thermal efficiency

Steam turbineSteam heat energy Mechanic rotation energy

Three types of turbines:

High pressure

Medium pressure

Low pressure

Real steam turbine

Different power steam turbinesCooling system Low-energy steam needs to be condensed

Water taken from a river takes up the heat of the exhausted steam and becomes hot.

Cooling towersCooling towers take liquid water and it falls over the hot steam circuit like a shower, and becomes steam.The huge cloud around a thermal power plant is only steam, not contamination.

Cooling towers vs chimneys The really painful chimney is narrower than the cooling towersThe smoke is darker and less striking than the white steam cloud

Cogeneration Definition:- Is a thermodynamically efficient use of fuel that generate electricity and useful heat at the same time.- A single machine produces simultaneously two types of energy.

- In traditional system the electric power was used but some energy must be discarded as waste heat,

- In cogeneration, this thermal energy is put to use.Evolution of thermal power stationAdvantages of cogeneration Efficiency decreases because electric power and heat are nearly simultaneously by cogeneration. Discharge of CO2 can be suppressed. Cogeneration is excellent in economical efficiency compared with the conventional method. Energy cost can be reduced. Usable energy is 70 percent of primary energy.Disadvantages of cogeneration While working, a mechanical sound is noisy. Efficiency cogeneration worse in summer, at the time the heat is not necessary.Equipment is having complicated structure. It raises the probability of breaking down and the costs of maintenance are increased. Renewable alternatives - Is an alternative energy to thermal power stations which generates electrical energy through the combustion of natural product, meaning that comes from nature without human intervention.biomass plantFuels used in thermal power plants1) petroleum : - Are primarily fuel obtained in the refining process crude.

- Its characteristics are adapted to the requirements of thermal power plants.

- It is highly polluting.

2) Natural gas:

- It is essentially a clean fuel whose use generates very little waste products.

- This consisting of a 97 percent methane (CH4)

3) Coal: -Heterogeneous sedimentary rocks originated from:differents plantsunder high pressureelevated temperaturecrustal movements