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WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, 371-375 HUNASHI DONG LU, GUNAGZHOU, CHINA PH: 0086-20-22378532 FAX: 0086-20-22378530

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Presentation on theme: "WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, 371-375 HUNASHI DONG LU, GUNAGZHOU, CHINA PH: 0086-20-22378532 FAX: 0086-20-22378530"— Presentation transcript:

1 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: TURBINES & POWER STATIONS CATLOGUE PROJECTS EXECUTED MODELS ABOUT US

2 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: A turbine converts energy in the form of falling water into rotating shaft power. The selection of the best turbine for any particular hydro site depends on the site characteristics, the dominant ones being the head and flow available. Selection also depends on the desired running speed of the generator or other device loading the turbine. Other considerations such as whether the turbine is expected to produce power under part-flow conditions, also play an important role in the selection. All turbines have a power-speed characteristic. They will tend to run most efficiently at a particular speed, head and flow combination. A turbine design speed is largely determined by the head under which it operates. Turbines can be classified as high head, medium head or low head machines. Turbines are also divided by their principle way of operating and can be either IMPULSE OR REACTION TURBINES. HIGH HEADMEDIUM HEADLOW HEAD IMPULSE TURBINES PELTONMULTI-JET PELTON REACTION TURBINES FRANCISKAPLAN TUBULAR The rotating element (called `runner') of a reaction turbine is fully immersed in water and is enclosed in a pressure casing. The runner blades are profiled so that pressure differences across them impose lift forces, like those on aircraft wings, which cause the runner to rotate. In contrast a impulse turbine runner operates in air, driven by a jet (or jets) of water. Here the water remains at atmospheric pressure before and after making contact with the runner blades. In this case a nozzle converts the pressurised low velocity water into a high speed jet. The runner blades deflect the jet so as to maximise the change of momentum of the water and thus maximising the force on the blades. Impulse turbines are usually cheaper then reaction turbines because there is no need for a specialist pressure casing. nor for carefully engineered clearances, but they are also only suitable for relatively high heads. TURBINES

3 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: Impulse turbines Impulse turbines are generally more suitable for micro-hydro applications compared with reaction turbines because they have the following advantages: greater tolerance of sand and other particles in the water, better access to working parts, no pressure seals around the shaft, easier to fabricate and maintain, better part-flow efficiency. The major disadvantage of impulse turbines is that they are mostly unsuitable for low-head sites because of their low specific speeds too great an increase in speed would be required of the transmission to enable coupling to a standard alternator. Reaction turbines The reaction turbines considered here are the Francis turbine and the propeller turbine. A special case of the propeller turbine is the Kaplan. In all these cases, specific speed is high, i.e reaction turbines rotate faster than impulse turbines given the same head and flow conditions. This has the very important consequences that a reaction turbine can often be compiled directly to an alternator without requiring a speed-increasing drive system. Some manufacturers make combined turbine-generator sets of this sort. Significant cost savings are made in eliminating the drive and the maintenance of the hydro unit is very much simpler. The Francis turbine is suitable for medium heads, while the propeller is more suitable for low heads. On the whole reaction turbines require more sophisticated fabrication than impulse turbines because they involve the use of larger and more intricately profiled blades together with carefully profiled casings. The extra expenses involved is offset by high efficiency and the advantages of high running speeds at low heads from relatively compact machines. Fabrication constraints make these turbines less attractive for use in micro-hydro in developing countries. Nevertheless because of the importance of low head micro-hydro, work is being undertaken to develop propeller machines which are simpler to construct. Most reaction turbines tend to have poor part-flow efficiency characteristics. TURBINES

4 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: A Pelton turbine consists of a set of specially shaped buckets mounted on a periphery of a circular disc. It is turned by jets of water which are discharged from one or more nozzles and strike the buckets. The buckets are split into two halves so that the central area does not act as a dead spot incapable of deflecting water away from the oncoming jet. The cutaway on the lower lip allows the following bucket to move further before cutting off the jet propelling the bucket ahead of it and also permits a smoother entrance of the bucket into the jet. The Pelton bucket is designed to deflect the jet through 165 degrees (not 180 degrees) which is the maximum angle possible without the return jet interfering with the following bucket for the oncoming jet. In large scale hydro installation Pelton turbines are normally only considered for heads above 150 m, but for micro-hydro applications Pelton turbines can be used effectively at heads down to about 20 m. Pelton turbines are not used at lower heads because their rotational speeds becomes very slow and the runner required is very large and unwieldy. If runner size and low speed do not pose a problem for a particular installation, then a Pelton turbine can be used efficiently with fairly low heads. If a higher running speed and smaller runner are required then the are two further options: - increasing the number of jets. Having two or more jets enables a smaller runner to be used for a given flow and increases the rotational speed. The required power can still be attained and the part-flow efficiency is especially good because the wheel can be run on a reduced number of jets with each jet in use still receiving the optimum flow. - twin runners. Two runners can be placed on the same shaft either side by side or on opposite sides of the generator. This configuration is unusual and would only be used if the number of jets per runner had already been maximised, but it allow the use of smaller diameter and hence faster rotating runners. PELTON TURBINE

5 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: Francis turbines can either be volute-cased or open-flume machines. The spiral casing is tapered to distribute water uniformly around the entire perimeter of the runner and the guide vanes feed the water into the runner at the correct angle. The runner blades are profiled in a complex manner and direct the water so that it exits axially from centre of the runner. In doing so the water imparts most of its pressure energy to the runner before leaving the turbine via a draft tube. The Francis turbine is generally fitted with adjustable guide vanes. These regulate the water flow as it enters the runner and are usually linked to a governing system which matches flow to turbine loading in the same way as a spear valve or deflector plate in a Pelton turbine. When the flow is reduced the efficiency of the turbine falls away. FRANCIS TURBINE

6 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: Kaplan turbine is most appropriate for operation with a low head a large amount of discharge. Owing to adjustable runner blades it offers the significant advantage to give high efficiency even in the range of partial load, and there is little drop in efficiency due to head variation or load. As a result of recent advantages, the range of Kaplan turbine applications have been greatly improved, which favors numerous undeveloped hydro sources previously discarded for economic or environmental reasons. As having adjustable runner blades, the construction of Kaplan turbine becomes naturally a bit complicated. The runner blade operating mechanism consists of a pressure oil head, a runner servomotor, and the blade operating rod inside the shaft etc. KAPLAN TURBINE

7 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web: Tubular turbine, gaining increasing interest throughout the world, is often selected in place of Kaplan turbine as a machine especially suitable for low-head development. Since the tubular type requires less space than other turbines, a saving in civil costs is realized due to a smaller powerhouse and shallow requirements for the draft tube. There are two types for this turbine, the pit type and the bulb type. The tubular turbine is equipped with adjustable wicket gates and adjustable runner blades. This arrangement provides the greatest possible flexibility in adapting to changing net head and changing demands for power output, because the gates and blades can he adjusted to their optimum openings. The wicket gate operating mechanism is installed inside the inner casing or outside the outer casing; and in both cases, spherical bearings are used to ensure highly smooth operation. The runner blade servomotor is contained in the runner hub, and the pressure oil for it is supplied from the oil head at the upstream end of the generator shaft. While, the runner hub is filled with lubricant oil fed from a gravity tank, which is located on the upper floor of the power house. As the turbine shaft seal, a mechanical seal or a labyrinth-type seal is adopted for easy maintenance. An opening in the concrete structure is provided around the discharge ring and the runner is installed or dismantled through that opening. TUBULAR TURBINE

8 WV GROUP CO., LTD. 2512, SOUTH TOWER, WORLD TRADE CENTER, HUNASHI DONG LU, GUNAGZHOU, CHINA PH: FAX: Web:


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