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Since it is a steam jet and no more a water jet who meets the turbine now, the laws of thermodynamics are to be observed now. The modern steam turbine is an action turbine (no reaction turbine), i.e. the steam jet meets from a being certain nozzle the freely turning impeller. There's a high pressure in front of the turbine, while behind it a low pressure is maintained, so there's a pressure gradient: Steam shoots through the turbine to the rear end. It delivers kinetic energy to the impeller and cools down thereby: The pressure sinks.
"Steam"Steam turbines are operated today of course no longer with normal water vapour only, but depending on the field of application also with other materials, e.g. with freons). Steam is produced in a steam boiler, which is heated in power stations by the burn of coal or gas or by atomic energy. Steam doesn't escape then, but after the passage through the turbine it is condensed in a condensor and then pushed back into the steam boiler again by a pump. This has the advantage that for example in nuclear power stations work- and cooling water are clearly separated.Multi-level steam turbinesIn modern steam turbines not only one impeller is propelled, but several being in a series. Between them idlers are situated, which don't turn. The gas changes its direction passing an idler, in order to perform optimally work again in the next impeller. Turbines with several impellers are called multi-level. The principle was developed 1883 by Parsons. As you know, with the cooling gas expands. Therefore it is to be paid attention when building steam turbines to a further problem: With the number of passed impellers also the volume increases, which leads to a larger diameter of the impellers. Because of that, multi-level turbines are always conical.Coupling of several turbines
Grafic: Coupled steam turbine. source: Helmut Hütten, "Motoren", Motorbuchverlag Stuttgart, S.379 In power stations today, different types of turbines are used in a series, e.g. one high pressure -, two medium- and four low pressure turbines. This coupling leads to an excellent efficiency (over 40%), which is even better than the efficiency of large diesel engines. This characteristic and the relatively favorable production make the steam turbine competitionless in power stations. Coupled with a generator and fired by an atomic reactor, they produce enormously much electric current. The strongest steam turbines achieve today performances of more than 1000 megawatts.
"Steam"Steam turbines are operated today of course no longer with normal water vapour only, but depending on the field of application also with other materials, e.g. with freons). Steam is produced in a steam boiler, which is heated in power stations by the burn of coal or gas or by atomic energy. Steam doesn't escape then, but after the passage through the turbine it is condensed in a condensor and then pushed back into the steam boiler again by a pump. This has the advantage that for example in nuclear power stations work- and cooling water are clearly separated.Multi-level steam turbinesIn modern steam turbines not only one impeller is propelled, but several being in a series. Between them idlers are situated, which don't turn. The gas changes its direction passing an idler, in order to perform optimally work again in the next impeller. Turbines with several impellers are called multi-level. The principle was developed 1883 by Parsons. As you know, with the cooling gas expands. Therefore it is to be paid attention when building steam turbines to a further problem: With the number of passed impellers also the volume increases, which leads to a larger diameter of the impellers. Because of that, multi-level turbines are always conical.Coupling of several turbines
Grafic: Coupled steam turbine. source: Helmut Hütten, "Motoren", Motorbuchverlag Stuttgart, S.379 In power stations today, different types of turbines are used in a series, e.g. one high pressure -, two medium- and four low pressure turbines. This coupling leads to an excellent efficiency (over 40%), which is even better than the efficiency of large diesel engines. This characteristic and the relatively favorable production make the steam turbine competitionless in power stations. Coupled with a generator and fired by an atomic reactor, they produce enormously much electric current. The strongest steam turbines achieve today performances of more than 1000 megawatts.
1 comment:
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