Hydro Turbines
Pelton turbines
Design principle and range of use
Pelton turbines with either vertical or horizontal shaft are intended for use of water energy at very high head (up to 1500 m) and relatively low discharge.
Pelton turbine is an impulse machine that transforms the potential energy of water into kinetic energy in a form of a water jet, which impacts and drives a Pelton runner.
General description & our setup
Litostroj Power manufactures both horizontal and vertical Pelton turbines. All setups include a main inlet valve, a bifurcation directing the water to the jet nozzles, which throw a jet on a Pelton runner bucket, where the kinetic energy of the jet is transformed into the torque driving the runner.
Each Pelton turbine is equipped with deflectors intended for cutting off the water jet from the nozzle so as to redirect it to tail water without hitting the runner. In such way, Pelton turbines are suitable for units with a long penstock without the need of a surge tank or another penstock safety element.
Horizontal Pelton turbine can be designed with either one runner or two runners mounted on the same shaft, with water supplied to each runner by one up to three nozzles.
Vertical Pelton turbine can be equipped with four to six jet nozzles and can successfully substitute a specifically slower Francis turbine. Even in case of a very large penstock, the control system of such Pelton turbine ensures stable operation of the unit.
Most Pelton runners are machined out of a single forged disk, which yields a supreme-quality product. The Pelton runner for larger units where such technology cannot be applied are either bolted or welded.
Another major advantage of the Pelton turbine is individual control of each nozzle, which enables turbine operation at a wide range of discharge.
Throughout the years, Litostroj Power has supplied or upgraded more than 80 Pelton turbines, with an output of 2,8 GW in total.
Types
- Horizontal Pelton units
- Vertical Pelton units
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Main features
- Heads from 50 m up to 1500 m
- Wide range of discharges
- Outputs up to 400 MW
- Runner diameters up to 4 m
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Francis turbines
Design principle and range of use
Francis turbine is characterized by a fixed-blade Francis runner that is hydraulically optimized for a narrow operating range.
Traditionally, Francis turbine has been considered to be a simple and robust machine suitable for exploitation of water energy at a wide range of head, from 30 m up to 750 m.
General description & our setup
The unit is normally isolated by means of a main inlet valve, which is positioned between the penstock and the welded steel spiral case. Francis turbine can be designed in either vertical or horizontal shaft setup.
The main advantage of a horizontal unit with Francis turbine is compact design, competitive price and simple assembly and maintenance.
But since such horizontal configuration has a limited capacity and size, the vertical setup is preferred for large units.
Depending on the water passage system safety or ramping requirements, a unit with Francis turbine can be equipped with a pressure relief or water-energy dissipation valve.
Our long experience in design and supply of the Francis turbine worldwide includes all the above setup options.
Our latest development of Francis runner hydraulic design has extended the range of use of the Francis turbine, that is, to a wider range of head and discharge. Litostroj Power offers a large variety of hydraulic design and other solutions custom-tailored for specific requirements and operating conditions of the unit and other customer’s needs.
Throughout the decades, Litostroj Power has supplied or upgraded more than 450 Francis turbines of different configurations, with an output of more than 15 GW in total.
Special solutions
Double Francis turbine is our unique horizontal solution with a single spiral case and two distributors, which can be controlled individually. Such solution offered by Litostroj Power allows to extend the operating range down to 15% (or below) of rated discharge and in this aspect represents an ideal solution for a plant with particularly varying discharge through the year.
Most recent achievement is a hydraulic profile which allows wide range operation even bellow 15% of rated discharge.
Types
- Vertical-shaft Francis turbine
- Horizontal-shaft Francis turbine
- Vertical or horizontal-shaft Francis turbine with pressure-relief (or ramping) valve
- Double Francis turbine
- Twin horizontal-shaft Francis turbine
- Camel-back unit with Francis turbine
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Main features
- Heads from 30 m up to 750 m
- Wide range of discharges
- Outputs up to 350 MW
- Runner diameters up to 7 m
- Wide range of nominal rotational speeds
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Selected references and publications
Dlouhe Strane, Czech Republic – largest single unit pump storage project in Europe with a Francis runner; unlimited operating range from 5 MW to 328 MW in turbine mode.
Kaplan Turbines
Design principle and range of use
Kaplan turbine is a double-regulated turbine. It is equipped with a Kaplan runner with variable-pitch blades that is hydraulically optimized for a wide range of discharge and a relatively wide range of head and is combined with regulated guide vanes, which makes a Kaplan turbine suitable for a wide range of discharge and head.
The governor enables optimizing the CAM relationship between the distributor and runner opening; this unique function enables Kaplan turbines to efficiently operate under versatile hydrological conditions.
Kaplan turbines are appropriate for use of water energy under different heads; typically, the head ranges from 5 m to 75 m.
General description & our setup
Litostroj Power has a long experience in design and manufacture of Kaplan turbines worldwide in various setup options. We apply the state-of-the-art technologies and the highest environmental standards, therefore we offer a great variety of hydraulic design considering the specific requirements and operating conditions of a unit with Kaplan turbine and offer comprehensive solutions tailored for each customer.
Typically the water is fed from the storage reservoir created by the dam to the spiral case. The spiral case is designed either as a concrete semi-spiral in case of a lower head (up to 35 m) or as a welded steel spiral for a head above 30 m.
As the Kaplan turbine operates with low speed, the static and rotating parts are heavy, with a high moment of inertia, and so very suitable for electric grid stabilization.
The unit is usually isolated by guide vanes only, but at a higher head, normally above 40 m, it can be also equipped with a main inlet valve. For units with a long intake channel we have references for design and installation of effective pressure relief systems which mitigate the transient surges.
Throughout the decades, Litostroj Power has supplied or upgraded more than 350 Kaplan turbines, with a total output of 8 GW.
Special solutions
Eco-friendly Kaplan runner is a highly-demanded solution on the markets with the most strict environmental standards. Its main advantage is in the absence of oil in the hub, which means no oil leaking into the river and environmental contamination whatsoever. We have experience in supplying either water-filled or empty (dry) eco-friendly Kaplan runners.
Refurbished Kaplan units - numerous Kaplan units around the globe have been in operation for more than 50 years and need to be refurbished. Litostroj Power offers various scopes of refurbishment, depending on the customer’s requirements. We offer improved hydraulic shape of the runner, new design and replacement of crucial components, such as replacement of grease or oil-lubricated bearings with self-lubricating bearings.
The refurbishment makes the unit operation more reliable, flexible, effective and environmentally acceptable. Refurbishment is executed at site in a short timeframe so as to shorten the interruption in unit operation to the minimum.
Propeller-type Kaplan turbine is a fixed-blade Kaplan turbine, which can be installed where small variation of flow through the turbine is expected and, in particular, on hydropower plants equipped with 4 or more units of the same type.
Semi-Kaplan turbine is a Kaplan-type turbine with fixed guide vanes. The single regulation – regulation of the runner blades - enables a flatter efficiency curve compared to that of the propeller type. Such setup requires controlled intake or draft tube gate to cut off the flow when the unit is to be stopped.
Main features
- Heads from 5 m up to 75 m
- Wide range of heads and discharges
- Outputs up to 110 MW
- Runner diameters up to 9,3 m
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Selected references and publications
Pit and Bulb turbines
Design principle and range of use
Pit and Bulb turbines are horizontal axial flow units equipped with a regulated Kaplan runner. These turbines are typically used at low heads (1,5 m to 25 m) and high discharges. The double regulation design allows wide operating range covering various heads and discharges.
General description & our setup
Pit and Bulb units are axial flow machines where the shaft, bearings, generator, brakes and other main unit equipment are all submerged within a sealed casing. This sealed casing can be either completely closed and submerged forming a typical bulb turbine, or the sealed casing can be extended upwards, forming a typical pit turbine.
Litostroj Power has a long history in design and supply of the tubular turbines worldwide in various setup options.
Pit configuration is typically used for smaller discharges and output powers. In most cases it is equipped with a speed increaser (gearbox), which allows the use of a smaller and more cost effective generator.
In the history of the Litostroj Power we have supplied or upgraded more than 20 Pit and Bulb units, which in total produce more than 260 MW of installed power.
Special solutions
LitoBulb is a small, compact design horizontal or inclined-shaft bulb unit, which is supplied pre-assembled to a large degree. Due to its compact design and factory preassembled parts the LitoBulb units have the benefits of simple and short site assembly.
Bulb units with inclined shaft - Depending on the site conditions, bulb units can be supplied with an inclined shaft, which reduces the overall unit length, depth of excavation on the intake side and consequently the cost of excavation works. Litostroj Power has already applied such solutions both on new installation and refurbishment projects.
Types
Main features
- Heads from 1,5 m up to 25 m
- Wide range of discharges
- Outputs up to 50 MW
- Runner diameters up to 9,3 m
- Wide range of nominal rotational speeds
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Selected references and publications
Saxo Turbines, Vertical tubular and S-type turbines
Design principle and range of use
The main characteristic of Saxo Turbines, Vertical tubular and S-type turbines is the axial flow arrangement of the unit, use of a conical distributor and absence of a spiral case. All unit types may be equipped with a regulated Kaplan runner, enabling the unit to operate efficiently under a wide range of discharges and heads.
These type of turbines typically cover the head range similar to Kaplan units, meaning they can be employed over 10-75 m heads, usually at discharges below 100 cms.
Saxo-type turbine is the most known Litostroj Power solution in the Vertical tubular unit arrangement. Throughout our history we have supplied more than 40 units of such type, they are suitable for new projects as well as old unit replacements.
General description & our setup
The Saxo turbine is a single or double regulated vertical tubular (axial flow) turbine without a spiral case structure at the inlet and represents a hybrid compact solution. It is a reliable and cost effective alternative to Kaplan and bulb units for electric energy production. The Saxo turbine was first introduced by Litostroj Power in 1996.
The Saxo turbine is designed as a compact solution limited in its size by the transport limitations. It is a factory pre-assembled to a maximum extent possible to reduce site installation time and related costs.
The main supporting part of the turbine is the intake elbow, to which the stay ring and the energy efficient conical distributor are attached. On the downstream side, the runner casing with the draft tube cone and draft tube elbow is placed.
Units are equipped with a Kaplan runner, turbine shaft is supported by an eco-friendly water lubricated turbine guide bearing situated in the turbine bulb. All loads from the bearing are transmitted through the stay vanes to the outer part of the stay ring and from there to concreted intake elbow.
Compact and factory pre-tested generator is placed outside the water passage above the turbine.
Special solutions
In order to fulfill the need of specific markets/customers some special solutions have been developed, such as:
- Runner with oil free hub and composite bearings in order to minimize environmental impact
- Use of a permanent magnet generator in combination of frequency converter in order to widen operation range of single regulated unit
- Various angles of inlet elbow in order to minimize civil works; designed on case by case basis
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Types
Our Vertical Bulb is a version of the Saxo-type turbine for a vertical tubular unit, with the inlet elbow replaced by an open-flume water inlet. The water flows vertically from an upstream basin into a conical distributor and then to the Kaplan runner and draft tube. The generator is attached to the inner cone of the stay ring and is submerged in water (design similar to bulb unit). Such design has the advantage of a further reduction of civil works on a replacement project.
The S-type unit is a horizontal variant of the Saxo-type unit. The inlet is similar as in the bulb unit whereas the S-shaped draft tube has two elbows, with the shaft passing through the draft tube elbow. The generator is attached to the foundation.
Main features
- Discharges up to 100 cms and Head ranges covered by Kaplan units
- Compact designs
- Price competitiveness and ease of maintenance compared to vertical Kaplan units
- Short delivery & erection times
- Excellent efficiency level over wide range of operation
- Environmentally friendly
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Selected references and publications
Reversible Pump Turbines
Design principle and range of use
Pump-turbines are used in pumped-storage hydropower plants (PSP). Their role in the electrical grid system is to store non used energy by transforming it to the potential energy of water. Pump-turbines can work either as a pump to store water in an upper reservoir or as a turbine to use the water to generate power. An additional role of pump-turbines and PSP systems in recent years has been balancing and stabilization of the electrical grid.
Litostroj Power provides state-of-the-art solutions tailored to customers’ demands in the most various environments. In order to achieve high efficiency and a wide operating range in both the pump and turbine regimes all machines are hydraulically optimized and model tested in Litostroj Power’s hydraulic laboratory.
General description & our setup
Pumped storage hydropower plants equipped with reversible units consist of two reservoirs (upper and lower) connected by a penstock. The reversible unit – located at the end of the penstock - is usually isolated by a main inlet valve, which is coupled to a welded steel spiral case where the guide vanes serve to control the unit discharge and power output.
The runner-impeller is hydraulically and mechanically designed to work in both pumping and power generating mode. Transition from pump to turbine regime can be very quick and repeated several times per day.
By means of the shaft, the runner-impeller is coupled to the generator-motor, which transforms the mechanical work into electrical energy or vice-versa.
Special solutions
Double-regulated Deriaz pump-turbine allows adjusting the runner blade angle similarly as in Kaplan runner and thus enables efficient use of water in turbine regime under a wide range of head and discharge conditions, on one hand, and adjustment of the power consumption during pump regime, on the other. Such ability to control the power consumption in pumping regime omits the need for variable speed generator. This solution is typically used at a lower head (up to 50 m).
Types
- Francis pump-turbine
- Deriaz-type pump-turbine
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Main features
- Energy accumulation
- Heads from 10 m up to 750 m
- Wide range of heads and discharges
- Outputs up to 350 MW
- Short starts and transitions (1-3 min)
- Runner diameters up to 7 m
- Grid frequency regulation
- Special design for non-restricted pumping power range available
- Generating power range from 2 - 100%
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Selected references and publications
Dlouhe Strane, Czech Republic – largest single unit pump storage project in Europe with Francis runner unlimited operating range from 5 MW to 328 MW in turbine mode operation.
Small hydro
Design principle and range of use
Compact turbines are characterized by small overall dimensions and can be of various types. Their compact design allows simple installation, with major turbine components transported to site pre-assembled.
General description & our setup
The majority of turbine types can be effectively implemented in a compact solution, with setup similar to a simplified setup of the large prototype of the same type. The compact design is optimized to simplify main turbine components and solutions used and to facilitate transport, quick installation and maintenance.
Types
- Small unit with Pelton turbine
- Small horizontal unit with Francis turbine
- Unit with double-flow Francis turbine
- Unit with Saxo-type turbine
- Pit unit
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Main features
- Compact size
- Delivery of pre-assembled turbine/components
- Ease of installation & maintenance
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