Energy

Electric plants with coal

Due to its wide availability, guaranteed supply, competitiveness and its very safe handling, transport and use (it is not inflammable, nor explosive, nor polluting for the soil or water), coal is the primary fuel for the creation of electric energy in the world and in Europe. The first step for energy creation in a coal plant starts in the steam generator area, where the burners are located for the combustion of coal fuel oil. The steam generator is generally made up of a furnace where air and fuel are inserted. When they burn, they heat and vaporize the water that runs in the pipes and serpentines that form the generator. In modern plants the coal is first grilled into very fine dust by increasing combustion speed; it is then driven to the kiln combustion chamber, where it is burnt at 1400°C. The high temperature of combustion gases determines the transformation of the boiler water contained in the pipes into steam. The vapour, through big pipes, reaches the turbine and makes it turn at 3000 turns per minute. The turbine is a machine that converts the kinetic energy of a moving fluid (liquid or gas) into mechanic energy. With regard to coal plants, the fluid is superheated steam. The main element of the turbine is the rotor, made up of a wheel with “blades”. The mechanic energy is then transmitted, through an axle, from the rotor to an electric generator, called alternator. The alternator, connected to a turbine, produces electric energy. The fumes, once they have released their heat into the steam generator, are sent to the chimney after having passed through the denitrificators, dust collectors and desulphurizers in order to eliminate nitrogen oxides, dusts and sulphur dioxide. The steam, after transmitting a large part of its energy to the turbine, is driven to the condenser where, without ever getting in contact with it, transfers its residual heat to the seawater collected with adequate pumps. This steam is then transformed into water, which is taken back to the steam generator in order to repeat the cycle. The energy produced by the alternator is subject to a tension increase of up to 380 kilovolts in order to be introduced into the electric network.