The condenser is a crucial element for the enterprise of steam engines and steam turbines. It serves for the liquefaction of the Abdampfes of these thermal engines. With the invention of the condenser by James Watt steam engines could be built for the first time, which had a comparatively small power requirement. Therefore the introduction of the condenser is considered as milestone of technology history.
James Watt used the simple design of the Einspritzkondensators for its machines. Into a separate container behind the steam discharge opening of the machine cold water is injected. Steam liquefies and leaves a nearly complete vacuum. This vacuum makes an improved utilization for the heat energy possible inherent in steam for the production of kinetic energy. Einspritzkondensatoren are also today still used; they became very rare however, since they cannot supply usable condensate for the supply of the steam boiler because of the entry of solved materials.
The today's air condensers in the form of the bank of tubes heat exchanger do not have this disadvantage. Here the cold cooling water is led by pipes into the evaporation area and evaporates condensed outside at the condenser tubes. The number of pipes in a condenser can be very large, then are in the condensers of a large nuclear power station up to 20.000 pieces of ever 10 m length. For the pipes a nominal size from 15 mm to 30 mm is typical. Within the condenser during the enterprise of the steam turbine the cooling water is warmed up around 8 to 10 "°C. A typical nuclear power station possesses for a steam turbine up to six of such condensers, which are flowed through in each case with up to 25000 m cooling water per hour. A such condenser transfers a thermal achievement from up to 700 megawatts of evaporates the turbine to the cooling water. The vacuum which can be reached in the condenser essentially depends on the inlet temperature of the cooling water as well as on the quality of the heat transfer in the individual pipes and can fall in very favorable cases on under 40 mbar.
A characteristic of these air condensers is the presence of steam lanes so mentioned. Among them one understands gaps in the Berohrung, by which turbine-evaporate more easily into the bank of tubes influxes can. Because of the edges of the steam lanes are the lane pipes. They possess a larger wall thickness opposite the normal pipes in the condenser, since they are exposed in the special measure to the Tropfenschlag of the saturated steam flowing in with high speed. Further those air in the condenser, which comes into the steam system by seals and not degassed feed water, collects itself. The labyrinth seal of the turbine shaft is particularly susceptible in this connection. Air transported by steam concentrates in the and from there constantly with a vaccum pump is preferably sucked off.
Usually condensers with water are cooled, which is taken from the environment and with its contamination as Fouling the function of the condenser endanger can. Already a thin dirt layer in the pipes of the condenser has substantial effects on the overall efficiency of a steam power plant. Therefore the water is cleaned over filtering units, the fine contamination in the pipes eliminates before during the enterprise special sponge rubber balls, which are brought with the Taprogge procedure into the cooling water and removed with large filters again.
The cooling water for the condensation is taken, if this is possible, directly from a river or a waters and led back again. In order to limit the cooling water quantities and the temperature of the returned cooling water, it is cooled down in cooling towers.
If no cooling water is available at the location of the power station, then in place of a water-cooled condenser an air capacitor (English air cooled more condenser) is used. This cools steam with ambient air. Air capacitors require substantially more place. The condensation pressure is limited by the ambient temperature. Air capacitors do not need however no cooling water and it result steam clouds as with the cooling tower. Air capacitors were built also into steam engines, in order to decrease their consumption of feed water (see Kondensationslokomotive).
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