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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Steam turbine. History of invention and production
Directory / The history of technology, technology, objects around us A steam turbine is a heat engine that converts steam energy into mechanical work. In the blade apparatus of a steam turbine, the potential energy of compressed and heated water vapor is converted into kinetic energy, which in turn is converted into mechanical work - the rotation of the turbine shaft. Steam from the steam boiler unit enters through the guide vanes on the curved blades fixed around the circumference of the rotor, and acting on them, causes the rotor to rotate.
Together with hydraulic turbines, the invention and distribution of steam turbines was of great importance for energy and electrification. The principle of their operation was similar to hydraulic ones, with the difference, however, that the hydraulic turbine was driven by a jet of water, and the steam turbine by a jet of heated steam. In the same way that the water turbine represented a new word in the history of water engines, the steam engine demonstrated the new possibilities of the steam engine. The old Watt machine, which celebrated its centenary in the third quarter of the XNUMXth century, had a low efficiency, since the rotational movement was obtained in it in a complex and irrational way. In fact, as we remember, the steam did not move the rotating wheel itself here, but put pressure on the piston, from the piston through the rod, connecting rod and crank, the movement was transmitted to the main shaft. As a result of numerous transfers and transformations, a huge part of the energy received from the combustion of fuel, in the full sense of the word, flew out into the pipe without any benefit. More than once, inventors tried to design a simpler and more economical machine - a steam turbine, in which a steam jet would directly rotate the impeller. A simple calculation showed that it should have an efficiency several orders of magnitude higher than Watt's machine. However, there were many obstacles in the way of engineering thought. In order for a turbine to truly become a highly efficient engine, the impeller had to rotate at a very high speed, making hundreds of revolutions per minute. For a long time this could not be achieved, because they did not know how to give the proper speed to the steam jet. It was not until 1883 that the Swede Gustav Laval managed to overcome many difficulties and create the first working steam turbine. A few years earlier, Laval had obtained a patent for a milk separator. In order to put it into action, a very high-speed drive was needed. None of the then existing engines did not satisfy the task. Laval was convinced that only a steam turbine could give him the necessary rotational speed. He began to work on its design and eventually achieved what he wanted. The Laval turbine was a light wheel, on the blades of which steam was induced through several nozzles set at an acute angle.
In 1889, Laval significantly improved his invention by adding conical expanders to the nozzles. This significantly increased the efficiency of the turbine and turned it into a universal engine. The principle of operation of the turbine was extremely simple. Steam, heated to a high temperature, came from the boiler through the steam pipe to the nozzles and burst out. In the nozzles, the steam expanded to atmospheric pressure. Due to the increase in volume accompanying this expansion, a significant increase in the outflow rate was obtained (when expanding from 5 to 1 atmosphere, the speed of the steam jet reached 770 m/s). Thus, the energy contained in the steam was transferred to the turbine blades. The number of nozzles and steam pressure determined the power of the turbine. When the exhaust steam was not released directly into the air, but was sent, as in steam engines, to a condenser and liquefied at reduced pressure, the power of the turbine was the highest. Thus, when the steam expanded from 5 atm to 1/10 atm, the jet velocity reached a supersonic value. Despite its apparent simplicity, the Laval turbine was a real marvel of engineering. It is enough to imagine the loads that the impeller experienced in it to understand how difficult it was for the inventor to achieve uninterrupted operation from his offspring. At huge speeds of the turbine wheel, even a slight shift in the center of gravity caused a strong load on the axle and overload of the bearings. To avoid this, Laval came up with the idea of putting the wheel on a very thin axle, which, when rotated, could bend slightly. When untwisted, it itself came to a strictly central position, which was then held at any speed of rotation. Thanks to this ingenious solution, the destructive effect on the bearings was reduced to a minimum. As soon as it appeared, the Laval turbine won universal recognition. It was much more economical than the old steam engines, very easy to handle, took up little space, and was easy to install and connect. The Laval turbine gave especially great benefits when it was connected to high-speed machines with saws, separators, and centrifugal pumps. It was also successfully used as a drive for an electric generator, but nevertheless, for it it had an excessively high speed and therefore could only act through a gearbox (a system of gears that lowered the rotation speed when transferring movement from the turbine shaft to the generator shaft). In 1884, the English engineer Parsons received a patent for a multi-stage jet turbine, which he invented specifically for driving an electric generator. In 1885, he designed a multi-stage jet turbine, which later became widely used in thermal power plants. She had the following device, reminiscent of a jet turbine device. A row of rotating wheels with blades was mounted on the central shaft. Between these wheels were fixed rims (discs) with blades that had the opposite direction.
Steam under high pressure was supplied to one of the ends of the turbine. The pressure at the other end was small (less than atmospheric). Therefore, the steam sought to pass through the turbine. First, he acted in the gaps between the shoulder blades of the first crown. These blades directed it to the blades of the first movable wheel. Steam passed between them, causing the wheels to turn. Then he entered the second crown. The blades of the second crown directed steam between the blades of the second movable wheel, which also came into rotation. From the second movable wheel, steam flowed between the blades of the third crown, and so on. All blades were given such a shape that the cross section of the interblade channels decreased in the direction of steam flow. The blades, as it were, formed nozzles mounted on the shaft, from which, expanding, steam flowed out. Both active and reactive power were used here. Rotating, all the wheels rotated the turbine shaft. Outside, the device was enclosed in a strong casing. In 1889, about three hundred of these turbines were already used to generate electricity, and in 1899 the first power station with Parsons steam turbines was built in Elberfeld. Meanwhile, Parsons tried to expand the scope of his invention. In 1894, he built an experimental vessel "Turbinia" driven by a steam turbine. In tests, it demonstrated a record speed of 60 km / h. After that, steam turbines began to be installed on many high-speed ships. Author: Ryzhov K.V.
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