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Steam turbine


Steam turbine
In addition to hydraulic turbines, described in a previous chapter, of great importance for Energy and Electrification was the invention and distribution of steam turbines. Their operating principle was similar to hydraulic, with the difference, however, that the hydraulic turbine drives the rotation of the jet of water and steam - jet of heated steam. Similarly, as the water turbine was a new word in the history of aquatic engines, steam demonstrated new capability of the steam engine. The old machine Watt, celebrated in the third quarter of the XIX century, its centenary, had low efficiency, because the rotational movement turned it difficult and inefficient way. In fact, as we recall, couples moved here not itself a spinning wheel, and put pressure on the piston, the piston rod through a connecting rod and crank movement is transmitted to the main shaft. As a result of the numerous programs and reforms is a huge part of the energy obtained from the combustion of fuel, in the full sense of the word without any benefit he flew into the pipe. More than once, the inventors have tried to construct a more simple and economical machine - a steam turbine in which the steam jet directly to the rotating impeller. A simple calculation shows that it must have the efficiency by several orders of magnitude higher than the machine of Watt. However, in the way of engineering proved a lot of obstacles. To do turbine into a high-performance engine, the impeller was rotated at a very high speed, making hundreds of revolutions per minute. For a long time it could not achieve because they do not know how to tell the proper speed jet of steam.

Only in 1883, the Swede Gustav Laval managed to overcome many difficulties and to create the first working steam turbine. In just a few years before Laval patented the milk separator. In order to bring it into action, you need a very high-speed drive. None of the then existing engines did not meet the task at hand. Laval was convinced that only the steam turbine can provide him with the necessary speed. He began working on its construction and eventually achieved the desired. Turbine Laval is a lightweight wheel, the blades of which a few set at an acute angle nozzles tide began to steam. In 1889, Laval significantly improved his invention, adding the nozzle cone expanders. This greatly increased the efficiency of the turbine and turned it into a universal motor. The principle of operation of the turbine was extremely easy. The steam heated to a high temperature coming from the boiler for the steam pipe to the nozzles, and was pulled out. The steam nozzle expanded to atmospheric pressure. By increasing the volume accompanying this extension receives a significant increase in the rate of leakage (when expanding from 5 to 1 atmosphere steam jet speed was 770 m / s). Thus enclosed in a pair of energy transmitted turbine blades. The number of nozzles and the steam pressure turbine power is determined. When the exhaust steam is directly discharged into the air and directed as in steam engines, and a condenser was liquefied under reduced pressure turbine has the highest power. Thus, during the expansion steam from 5 atm to 1/10 atm stream reaches supersonic velocity value.

Despite its apparent simplicity, the turbine Laval was a miracle of engineering. It is enough to imagine the stress that it has experienced in the impeller to understand how difficult it was to achieve the inventor of their offspring uptime. With enormous speed of the turbine wheel, even a slight shift in center of gravity caused a heavy load on the axle bearings and overload. To avoid this, Laval invented the wheel to impose a very thin axle, which is in rotation could bend slightly. When unwinding she came in a strictly central position, held by then at any speed. Thanks to this ingenious solution destructive effect on the bearings has been reduced to a minimum.

Hardly appeared, turbine Laval won universal recognition. She was much more economical than the old steam engines, it is very simple to use, takes up little space, is easy to install and connect. Especially great benefits turbine Laval gave in its connection with high-speed machines saws, separators, centrifugal pumps. It is successfully used as a drive for an electric generator, but all the same to him she had excessively high speed, and therefore could act only through a reduction gear (gear system lowers the rotation speed of the transmission of motion from the turbine shaft to the generator shaft).

In 1884, the English engineer Parsons received a patent for a multi-jet turbine, which he invented specifically for the actuation of the electric generator. In 1885 he designed a multi-jet turbine, which has been subsequently widely used in thermal power plants. She had the following device resembling a device reactive hydro turbine. On the central shaft was planted a series of rotating wheel with blades. Between these wheels were fixed rims (wheels) with blades that took the opposite direction. The vapor was fed under high pressure to one end of the turbine. The pressure at the other end there was a small (less than atmospheric). Therefore, couples tried to pass through the turbine. First, it is fed into the spaces between the blades of the first crown. These blades sent him on the shoulder of the first rolling wheel. Steam is passed between them, causing the wheel to rotate. Then he did a second crown. The blades of the second crown sent between pairs of the second rolling wheel paddles, which also occurred in the rotation. From the second movable wheel pairs done between the shoulder blades of the third crown and so on. All blades was shaped so that the cross section mezhdulopatochnyh channels decreases towards pair expires. Shoulders as if impaled formed on the nozzle shaft of which, extending expiring pairs. It was used both active and reactive power of it. Spinning, all-wheel rotating shaft of the turbine. Outside, the device was placed in a sturdy casing. In 1889, already about three hundred of the turbines used to generate electricity, and in 1899 the first power plant with steam turbines Parsons was built in Elberfeld. Meanwhile, Parsons tried to broaden the scope of their invention. In 1894 he built an experimental boat "turbine" driven by a steam turbine. In tests, it has demonstrated a record speed of 60 km / h. Thereafter, steam turbines were installed in many high-speed vessels.

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