2Steam Power PlantConverts the energy stored in fossil fuels (coal,oil,natural gas) or fissile fuels (uranium,thorium) into electricity.
3Fossil Fuel Power Plant A fossil fuel power station uses fuel to boil water, turning it into steam. This steam is then used to turn turbines ( sets of blades). The turbine is connected to the generator ( alternator) which is spun by the turbines. The generator makes electricity which is then distributed around the country using transformers and the National grid.
5Fossil Fuel Power Plant They are normally run with natural gas as a fuel, although low-sulfur fuel oil can also be used as needed. The turbines operate like a jet engine: they draw in air at the front of the unit, compress it, mix it with fuel, and ignite it. The hot combustion gases then expand through turbine blades connected to a generator to produce electricity.
7Natural Gas Power Plant Natural gas is the easiest of the fossil fuels to burn as it mixes well with air and burns cleanly with little ash. The gas is piped directly to the plant, otherwise, it is difficult to store unless cryogenic temperature tanks are available. For instance, overseas gas is converted to liquified natural gas (LNG) for transport (at -197°F). Natural gas high in hydrogen sulfide (H2S) is known as sour gas (versus sweet gas).
11Carnot CycleIt is the most efficient cycle for converting a given amount of thermal energy into work, or conversely, creating a temperature difference (e.g. refrigeration) by doing a given amount of work.A system undergoing a Carnot cycle is called a Carnot heat engine, although such a 'perfect' engine is only a theoretical limit and cannot be built in practice.
12Carnot CycleThe thermal efficiency (η) of Carnot cycle η = (T1 – T2)/T1T1 = Temperature of heat sourceT2 = Temperature of receiver
13Rankine CycleConverts heat into work. The heat is supplied externally to a closed loop, which usually uses water as the working fluid.Steam engine and steam turbines in which steam is used as working medium follow Rankine cycle.This cycle can be carried out in four pieces of equipment joint by pipes for conveying working medium
15Brayton CycleDescribes the workings of the gas turbine engine, basis of the jet engine and others.A gas turbine extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between.The high velocity and volume of the gas flow is directed through a nozzle over the turbine's blades, spinning the turbine which powers the compressor and, for some turbines, drives their mechanical output. The energy given up to the turbine comes from the reduction in the temperature and pressure of the exhaust gas.
18Combined Cycle Power Plant High Overall Plant EfficiencyEfficiencies exceeding 50% can be attainedLow Investment Cost2/3 of the output is produced in a Gas Turbine and 1/3 in steam turbine, the investment costs required are approximately 30% less than a conventional steam power plant.Small Amount of Water requiredThe amount of cooling water required is only 50% as mush as for a steam plant
19Combined Cycle Power Plant Great Operating FlexibilityPhase installationThe gas turbines can go into operation much sooner than the steam plant. The gas turbine plant can keep on generating power as the steam plant is under construction.Simplicity of operationIt is simpler to run than a conventional steam power plant.Low Environmental ImpactAdvantages for Cogeneration
20Why Coal is an Important Energy Source? Coal is the oldest energy type in the world.Coal is plentiful and spread all over world. More then 70 countries have coal reserves.Coal is the most safe fossil energy source to use,transport and stock.Coal is not polluting nature with clean coal technologies.Coal is a cheap energy source for producing electricity.Coal is a trustworthy energy source because it spread all over world.
21What is Coal?Coal is a combustible, sedimentary, organic rock, formed from vegetation. In other words, coal is a fossil fuel created from the remains of plants that lived and died about 100 to 400 million years ago. Coal is classified as a nonrenewable energy source because it takes millions of years to form.
22Types of Coal Bituminous coals Sub-bituminous coals Brown coals Anthracite
24Modern Coal Power Plant Coals are classified in order to identify end-use, and also to provide data useful in specifying and selecting burning and handling equipment, and in the design and arrangement of heat transfer surfacesBecause of the cost of transportation coal-fired plants are sometimes built next to the coal mine (i.e., a mine mouth plant).
29Stoker FurnaceThe stoker furnace is of limited capacity and does not lend itself to power plants but rather it is used in industrial processes. Coal is introduced on a grate, and it is finally burned on a stationary bed.The primary air enters below the burning bed and initiates the combustion process, and also cools the grate. Secondary air is introduced over the burning bed to complete the combustion process.
30Cyclone FurnaceThe cyclone furnace employs several (as many as 16) independent combustion chambers. The main combustion chamber operates at a temperature of 3200°F. These were popular in the 1950s and 1960s but are no longer being built since they have difficulty burning low-sulfur coals and the high temperature results in significant NOx formation.
31Pulverized Coal Furnace The pulverized coal furnace attempts to burn finely powdered coal and air in a gaseous torch. This is accomplished through pulverizing the coal by crushing, impact and attrition (rubbing) of the coal to a size finer than face powder (diameter < 0.3 mm). The primary air dries and transports the coal.
32The Advantages and Disadvantages of a Pulverized Coal Furnace The advantages of a pulverized coal furnace include its ability to burn all ranks of coal from anthracitic to lignitic, and it permits combination firing (i.e., can use coal, oil and gas in same burner). Because of these advantages, there is widespread use of pulverized coal furnaces.The disadvantages of the pulverized coal furnace are that the coal pulverizer has a significant power demand of its own and requires more maintenance, flyash erosion and pollution complicate unit operation and increase exhaust system maintenance requirements, and pulverized systems have higher initial cost and require larger furnace volumes for the combustion process.
33Fluidized-Bed Furnace For a fluidized-bed furnace, the velocity of combustion gas (air) entering the bottom of the furnace is maintained such that the coal and limestone or dolomite particles are suspended (resembling a boiling liquid). The boiler tubes are immersed in the fluidized bed. Fluidized-bed combustion systems are categorized as pressurized vs. atmospheric bed systems, and circulating vs. stationary bed systems.
34Advantages of Fluidized-Bed Furnice The primary advantage is reduced pollutants, for example, the lower furnace temperatures means reduced NOx production. In addition, the limestone (CaCO3) and dolomite (MgCO3) react with SO2 to form calcium and magnesium sulfides, respectively, which are solids that do not escape up the stack; however, it does require about 50% more limestone/dolomite as compared to a wet-scrubber system. This means the plant can easily use high sulfur coal.
35Disadvantages of Fluidized-Bed Furnice Erosion of tubes by the particles rubbing the tubes,Requires more fan power to suspend the particles, andSystem appears better suited for low-power applications.