EN  Welcome!       

Para Português PT (parte) clique aqui
Для русской версии RU (частично) нажмите здесь


Registrations
DUNS: 400106873
Reg. in CCR & ORCA
NATO NCAGE: B6183
Reg. in Lux: B 32.016
Lux tax 1989 2406 173
EU VAT: LU 14308966
US EIN: 98-0497131

APPLICATION EXAMPLES
Uprating acceptable?
Identification of weak parts
Cavitation quality assessment
Runner improvement
Guide vanes improvement
Operation optimisation Francis
Operation optimisation Bulb
Cavitation as a diagnostic tool

METHODS
What is cavitation?
Physical background
How many sensors?
Raw cavitation data
Cavitation characteristics
Cavitation mechanisms
Spatial distribution
Calibration
How do we work?
Cavitation monitoring
Model vs. prototype

DOWNLOAD
Papers
Leaflets

CONTACTS

Cavitation erosion on a Francis runner

Letter to O&M Manager
(Click to read)


What is Korto?

Since 1996, our company has been providing highly specialised, leading-edge services and products to the hydropower industry.

Our staff is a highly specialised team of world-renowned experts from seven countries.

Our background lies in advanced proprietary methods and leading-edge research based on extensive full-scale experience.

Korto’s motto: Stay with the problem until it is solved.

Our Products

MULTIDIMENSIONAL CAVITATION MONITORING SYSTEMS

• Use
- Independent use
- As a cavitation channel of the plant monitor
• System configuration
- Typically 6 sensors per turbine
- One cavitation processor per turbine
- One control unit per plant (if used independently)
• Features
- High-sensitivity detection of deterioration effects
- Coverage of all cavitation segments
- Diagnostic functions
• Data
- True total cavitation intensity
- Assessment of spiral-case and distributor influence
- Runner-blade resolution
- Accumulated cavitation intensity
• Implementation
- Multidimensional algorithm
- FPGA/RT Technology
- Ethernet connection to plant/company network
• Options
- Operation data input
- Analog total cavitation intensity output
- Control unit
• Application
- Operation optimization
- Tracking changes, detection of incidents
- Predictive turbine maintenance

Cavitation sensors are installed in robust protection boxes on 6 or 8 guide-vane shafts or links.

Cavitation sensors are installed in robust protection boxes on 6 or 8 guide-vane shafts or links.

Cavitation processor (gray box on the wall) is installed close to the distributor.

Cavitation processor (gray box on the wall) is installed close to the distributor.

Cavitation processor Type 7391P (internal view)

Cavitation processor Type 7391P (internal view).

Cavitation Monitoring System Type 7391 - Connections, Options

Cavitation Monitoring System Type 7391 - Connections, Options

Details: download PDF 843 kB


Our Services

ON-SITE MULTIDIMENSIONAL DIAGNOSTIC CAVITATION TESTS

Please click to see PDF (596 kB).

A small vibro-acoustic laboratory is installed close to the distributor. Turbine operation is minimally disturbed.

A small vibro-acoustic laboratory is installed close to the distributor. Turbine operation is minimally disturbed.

Our Technique

We use our own multidimensional vibro-acoustic technique which:

• Identifies cavitation mechanisms
• Assesses the role of turbine parts in cavitation
• Yields data on the spatial distribution of cavitation
• Senses all cavitation segments in the turbine
• Delivers detailed turbine cavitation characteristics
• Detects adverse effects with high sensitivity


When Might You Need Us?

• Commissioning a turbine:
- Model predictions correct?
- Contract requirements met?
• Refurbishing or uprating a turbine:
- True state before and after refurbishment/upgrade
• Routine operation:
- Operation optimisation to achieve minimum erosion
- Maintenance optimisation in respect
- Control of ageing effects and incidents


Some Projects

EFFICIENCY AND CAVITATION IN CAM OPTIMISATION OF A KAPLAN TURBINE

The cam of the 28-MW Kaplan turbine at Kembs HPP of Electricité de France was optimised in a prototype test. Cavitation was also measured; the multidimensional method was applied. Two cam definitions were checked: one from the model test, and one optimised in the prototype test. The two cam definitions yield substantially differing efficiency values and cavitation intensity values:

Cavitation intensity vs. power for two cams: Black - optimised cam; Red - cam defined in the model test

Cavitation intensity vs. power for two cams: Black - optimised cam; Red - cam defined in the model test

Detailed analysis shows that strong cavitation appears only within a narrow circumferential interval behind the spiral casing:

Normalised cavitation intensity vs. angular position for different power values

Normalised cavitation intensity vs. angular position for different power values

This suggests it is possible to improve the turbine behaviour by changing the inclination and/or profile of the stay vanes in the critical circumferential interval.

A new cam was installed and an anti-cavitation layer was applied on the endangered part of the runner. The result: the metal loss found earlier after 1500 hours is now found only after 8000 hours.

More info: info@korto.com or Mr. Philippe Gauvin, Electricité de France - CIH, philippe.gauvin@edf.fr or Mrs. Marie Delagarde, Electricité de France - DTG, marie.delagarde@edf.fr


CAVITATION MONITORING - FRANCE

Following the multidimensional cavitation test at Kembs 1 Kaplan unit of EDF, France, a broadened multidimensional cavitation monitor was left there. It consists of 20 cavitation sensors, remote-sensors unit, and the central processor.

20+4+4 cavitation sensors on Kembs 1

20+4+4 cavitation sensors on Kembs 1

The aim of this hybrid installation - the cavitation monitor and the automatic cavitation-data acquisition system - is to deliver detailed cavitation data at various operation points which were not reached during the test.

Pascal Ratabouil of EDF installing the central processor

Pascal Ratabouil of EDF installing the central processor

More info: info@korto.com or Mr. Philippe Gauvin, Electricité de France - CIH, philippe.gauvin@edf.fr or Mrs. Marie Delagarde, Electricité de France - DTG, marie.delagarde@edf.fr or Mr. Pascal Ratabouil, Electricité de France - GMH Est-EIS, pascal.ratabouil@edf.fr


CAVITATION IN A 650 MW FRANCIS TURBINE

Korto tested a 650-MW Francis turbine at the Third Powerplant of the USBR's Grand Coulee Dam, which is the largest electric power producing facility and the largest concrete structure in the USA.

Grand Coulee Dam has 6800 MW of installed generating capacity in its four hydropower plants.

Grand Coulee Dam has 6800 MW of installed generating capacity in its four hydropower plants.

The turbine global cavitation characteristics, which gives the erosion rate as a function of turbine power setting, are determined (black curve, below). Combined with the power setting statistics (blue), they yield an estimate of the contribution of each power setting to the erosion (red).
Such data can be used for operation optimisation and, if delivered by permanent monitoring, for maintenance optimisation.

Cavitation data (black and red) are compared to the turbine efficiency (violet). Power scale: 340-700 MW.

Cavitation data (black and red) are compared to the turbine efficiency (violet). Power scale: 340-700 MW.

Quite uniform cavitation quality of the runner blades was found. The mean runner cavitation intensity behind different sections of the spiral casing is determined (below). This shows that the spiral casing is not optimal with respect to cavitation.

In this test three techniques for cavitation diagnostics and monitoring are compared:
(1) Simple: One sensor on a wicket gate link - simple data processing
(2) Simple: One sensor on the draft tube wall - simple data processing
(3) Multidimensional: Sensors on all wicket gate links - complex data processing. - This is Korto's approach to obtain the data shown above.

Blade-passage modulation amplitude vs. turbine power setting as measured in different sensor locations

Blade-passage modulation amplitude vs. turbine power setting as measured in different sensor locations

In 24 positions of the sensor in (3) different estimates of the cavitation intensity were obtained. As a function of turbine power setting, they are presented in different colours above. The final result in (3), derived from all these data, incorporates contributions from all locations in the turbine and all cavitation mechanisms, while only one curve (black) is used as the final result in (1). Obviously, the results of the one-sensor techniques, thus also of (1) and (2), are quite arbitrary.
A further disadvantage of (2) is sensor's location. The sensor on the draft tube wall of the Francis turbine predominantly senses free vortices in the draft tube. Using its readings to estimate erosive rotor cavitation results in false conclusion:

Green...no cavitation, yellow...weak cavitation, red...strong cavitation

Green...no cavitation, yellow...weak cavitation, red...strong cavitation

In (3), various special signal and data processing tools, such as "worms" shown below, are used to identify different cavitation mechanisms, determine the role of different turbine elements in cavitation processes, and derive un-biased estimates of cavitation intensity. None of this is possible with the simple methods.

Cavitation intensity (colour) vs. instantaneous runner angular position (horizontal) and power setting (vertical - 350 MW top, 700 MW bottom)

Cavitation intensity (colour) vs. instantaneous runner angular position (horizontal) and power setting (vertical - 350 MW top, 700 MW bottom)

More info: info@korto.com or Mr. G. Michael Strombach, USBR Grand Coulee Dam, mstrombach@pn.usbr.gov


 

News & Events

Korto at HYDROVISION BRAZIL 2011

The first HydroVision conference in Brazil

took place in Barra da Tijuca, Rio de Janeiro, on September 20-22.

The Korto banner on the conference site presents Korto as a sponsor.

The Korto banner on the conference site presents Korto as a sponsor.

Korto had a booth at the exhibition. Korto's profile and a review of products can be seen on the conference site.

Korto at HYDROVISION INTERNATIONAL 2011

The first hydropower event in 2011 took place in Sacramento, California, USA, on July 19-22.

3,451 delegates attended 70 sessions with over 450 speakers and over 260 exhibiting companies.

3,451 delegates attended 70 sessions with over 450 speakers and over 260 exhibiting companies.

Korto had a booth at the exhibition.

Ms. Luana Fidelis Silva of Zollern Co. as Korto's guest

Ms. Luana Fidelis Silva of Zollern Co. as Korto's guest

B. Bajic presented a paper (download PDF 3086 kB), and at VibroSystM's annual workshop on machine condition monitoring (program PDF 57 KB), he spoke about cavitation monitoring and diagnostics (download PDF 1810 kB).

KORTO IN RUSSIA

Korto at HydroVision Russia, Moscow, March 2011

At this joint event with Russia Power 2011 Conference Korto had a booth at the exhibition. Korto shared it with VibroSystM. The occasion was used to discuss the possibility of partnership between VibroSystM and Korto.

From left: Marius Cloutier, President, VibroSystM; Imi Holderna, Senior Business Representative, VibroSystM; and Branko Bajic, Managing Director, Korto.

From left: Marius Cloutier, President, VibroSystM; Imi Holderna, Senior Business Representative, VibroSystM; and Branko Bajic, Managing Director, Korto.

At the conference, B. Bajic made a presentation on multidimensional cavitation monitoring in FPGA/RT technology (download PDF 5530 kB).


Russia Power Conference, Moscow, April 2010

This three-day conference incorporated a hydropower track. Korto presented the paper “Multidimensional scanning of turbine cavitation” (download PDF 2200 kB).

B. Bajic of Korto (left) with the veterans of Russian hydropower science, Anatoly A. Sotnikov, Project Chief Designer (middle), and Igor Pylev, Deputy Chief Designer, both from OJSC Power Machines, St. Petersburg

B. Bajic of Korto (left) with the veterans of Russian hydropower science, Anatoly A. Sotnikov, Project Chief Designer (middle), and Igor Pylev, Deputy Chief Designer, both from OJSC Power Machines, St. Petersburg

The conference was an excellent place to meet Russian hydropower specialists.

KORTO IN SPAIN

Gas Natural Fenosa: Peares

A test has started at Peares HPP aiming at the diagnosis of cavitation on runners and in the draft tubes of three Francis 60-MW turbines with very wild behaviour in rough zones.

From left to right: Hugo Rodriguez Rodriguez, Fenosa; Jose Manuel Lorenzo Gomez, Fenosa, Branko Bajic, Korto

From left to right: Hugo Rodriguez Rodriguez, Fenosa; Jose Manuel Lorenzo Gomez, Fenosa, Branko Bajic, Korto

Measurement lasting one hour was sufficient to acquire runner-cavitation data and obtain a rough estimate of global cavitation characteristics; much more time will be needed to reveal all the cavitation details.

Screen of the test-controlling computer

Screen of the test-controlling computer

An estimate of global cavitation characteristic can be seen on the graph in the middle. Here is the same in better resolution: PDF 329 kB

KORTO IN BRAZIL

Cavitation Test at Ilha Solteira HPP

The R&D project "Application of Acoustic Emission Technique for Detection of Discontinuities in Turbine Blades", financed by ANEEL and realised by Physical Acoustic South America - PASA, and Cia Energética de São Paulo - CESP, was broadened to include diagnotics of runner cavitation. Korto was asked to test two turbines at Ilha Solteira which differ in the trailing-edge form of the pre-distribuidor vanes.

Ilha Solteira, the third biggest HPP of Brazil and among ten biggest in the world, has 20 Francis turbines wich generate a total of 3444 MW.

Ilha Solteira, the third biggest HPP of Brazil and among ten biggest in the world, has 20 Francis turbines wich generate a total of 3444 MW.

The multidimensional technique based on 26 cavitation sensors was applied.

From left: Allan Machado and Renato Farias of PASA, Alcides Souza and Ricardo Avante of CESP, Laura Cabral and Branko Bajic of Korto

From left: Allan Machado and Renato Farias of PASA, Alcides Souza and Ricardo Avante of CESP, Laura Cabral and Branko Bajic of Korto

More info: info@korto.com or Sr. Alcides Donizeti Souza, CESP, alcides.souza@cesp.com.br

Visit to Capivara HPP of Duke Energy

Korto's team visited Capivara and discussed with Mr. Renato Jose Baccili Castilho, Manager, Mr. Vincente Borro, Electro-Mechanical Maintenance Engineering, and their collaborators the specific problem experienced by the four Francis 150-MW turbines at Capivara. Since they are used for frequency stabilisation, they are exposed to a rapid and strong fluctuating load. The question arises of the financial costs resulting from the deterioration effects, among others things, caused by cavitation.

Partnership in Brazil

At a meeting at the headquarters of Monitoring and Diagnostics - M&D, in Rio de Janeiro, Mr. Hélio Ricardo T de Azevedo, Director, Mr. Saderson Pereira S de Souza, Engineering Manager, both from M&D, Dr. Branko Bajic and Mrs. Laura Cabral, from Korto, discussed cooperation between the two companies, where Korto will support M&D with the cavitation channels of M&D’s monitoring systems and M&D will promote Korto’s interests in Brazil.

From right to left: Hélio Ricardo and Sanderson Pereira, M&D, and Laura Cabral e Branko Bajic, Korto

From right to left: Hélio Ricardo and Sanderson Pereira, M&D, and Laura Cabral e Branko Bajic, Korto

KORTO AT HYDRO 2010

The biggest international conference on hydro power, HYDRO 2010, www.hydropower-dams.com, took place in Lisbon, Portugal, at the end of September.

Korto had a booth at the accompanying exhibition. These posters were shown:
- HPP Grand Coulee (download PDF 2408 kB)
- HPP Burfell (download PDF 1680 kB)
- HPP Kembs (download PDF 2408 kB)
- HPP Belesar (download PDF 561 kB)
- Korto Cavit Monit (download PDF 731 kB)

Korto booth

Korto booth

Many interesting and important people paid us a visit.

From left: Sergey Yudin, Project Manager, Energomashexport; Marius Cloutier, President, VibroSystM; Imi Holderna, Senior Business Representative, VibroSystM; Laura Cabral, Korto; Branko Bajic, Korto

From left: Sergey Yudin, Project Manager, Energomashexport; Marius Cloutier, President, VibroSystM; Imi Holderna, Senior Business Representative, VibroSystM; Laura Cabral, Korto; Branko Bajic, Korto

Korto's paper on the multidimensional technique for diagnostic and monitoring of turbine cavitation was presented (download PDF 1350 kB).

More info: info@korto.com

KORTO IN FRANCE

Electricité de France - Kembs

A team comprised of Electricité de France, Andritz Hydro, and Korto Cavitation Services

From left to right - Standing: Roland Blaser, Andritz; Philippe Gauvin, EDF; Marcel Saugy, Andritz; Pascal Ratabouil, EDF, Michel Salvi, Andritz; Branko Bajic, Korto; Sitting: Nadine Pajean, EDF; Marie Delagarde, EDF; Benjamin Dufils, EDF

From left to right - Standing: Roland Blaser, Andritz; Philippe Gauvin, EDF; Marcel Saugy, Andritz; Pascal Ratabouil, EDF, Michel Salvi, Andritz; Branko Bajic, Korto; Sitting: Nadine Pajean, EDF; Marie Delagarde, EDF; Benjamin Dufils, EDF

made a complex test of the refurbished and upgraded 28-MW Kaplan unit 1 at Kembs HPP.

Kembs (black square) is the first in a chain of 11 hydropower plants on the Grand d'Alsace in North-East France.

Kembs (black square) is the first in the chain of 11 hydropower plants on the Grand Channel d'Alsace in North-East France.

Korto's task was to estimate the cavitation behaviour of the unit.

www.korto.com

Copyright ® 2004 Korto Cavitation Services