Presentation on theme: "Fossil Fuel Power Plants Coal, oil and gas are called "fossil fuels" because they have been formed from the organic remains of prehistoric plants and animals."— Presentation transcript:
Fossil Fuel Power Plants Coal, oil and gas are called "fossil fuels" because they have been formed from the organic remains of prehistoric plants and animals Coal provides around 28%, and Oil provides 40%.
Fossil Fuel Power Plants Coal is crushed to a fine dust and burnt Crushed coal is known as Pulverized Oil and gas can be burnt directly. The main bit to remember:
Advantages Very large amounts of electricity can be generated in one place using coal, fairly cheaply. Transporting oil and gas to the power stations is easy. Gas-fired power stations are very efficient. A fossil-fuelled power station can be built almost anywhere, so long as you can get large quantities of fuel to it.
Disadvantages Basically, the main drawback of fossil fuels is pollution. Burning any fossil fuel produces carbon dioxide, which contributes to the "greenhouse effect", warming the Earth. Burning coal produces more carbon dioxide than burning oil or gas. It also produces sulphur dioxide, a gas that contributes to acid rain. We can reduce this before releasing the waste gases into the atmosphere.
Coal Fired Power Plants Burning coal produces sulphur dioxide, an acidic gas that contributes to the formation of acid rain. This can be largely avoided using "flue gas desulphurisation" to clean up the gases before they are released into the atmosphere. This method uses limestone, and produces gypsum for the building industry as a by-product. However, it uses a lot of limestone.
Oil Fired Power Plants Crude oil (called "petroleum") is easier to get out of the ground than coal, as it can flow along pipes. This also makes it cheaper to transport.
Gas Fired Power Plants Natural gas provides around 20% of the world's consumption of energy, and as well as being burnt in power stations, is used by many people to heat their homes. It is easy to transport along pipes, and gas power stations produce comparatively little pollution.
Steam Turbine 3 A steam turbine is a form of heat engine in which two distinct changes of energy take place. The available heat energy of the steam first is converted into kinetic energy by the expansion of the steam in suitably shaped passage, or nozzle, form which it issues as a jet, at a proper angle, against curved blades mounted on a revolving disk or cylinder and by the reaction of the jet itself as it leaves the curved passage. The pressure on the blades, causing rotary motion, is due solely to the change of momentum of the steam jet during its passage through these blades. There is two major different part of steam turbine contruction : 1) Stator, 2) Rotor.
Steam Turbine 3 Conventional turbines consist of a shaft with blades mounted upon it. This looks very much like closely spaced propeller blades that are pushed by pressure exerted through gas or air which causes the shaft to rotate. Conventional steam turbines have inlets near the center of a shaft with the gas/steam expanding out toward the ends with the blades becoming progressively larger from the center to the end. See the photo below of a conventional steam turbine shaft and blade assembly, the far right of the photo is where the gas/steam enters on this model and it expands and exits on the left.
Steam Turbine 4 These turbine shaft/blade assemblies can weigh as much as 40 tons and spin at 3,600 rpm. That’s a lot of mass spinning very fast. When a steam resource with high total dissolved solids is pushed through conventional turbine systems, it results in scaling, friction, and loss of efficiency. The higher the TDS, the more frequently these devices require maintenance, expensive both in absolute terms and lost opportunity.