Maintenance key to plant life extension

Paul Boughton

Serious investment is being made in maintenance and refurbishment of power generating plant as the world's demand for electricity continues to grow. Sean Ottewell reports.

Alstom is the leader of a consortium, including Orteng and Camargo Correa, selected by Cemig (Companhia Energética de Minas Gerais) to refurbish the São Simão hydro plant, Cemig's most powerful facility, located in Paranaíba river, between Goiás and Minas Gerais States. The consortium will be responsible for the refurbishment of generation and transmission equipment.

Approximately 30 per cent of the hydro plants in Brazil have been operating for over 30 years, which can generate a significant refurbishment market. São Simão, with six generating units and an output of 1710MW in power generation, started its operations in 1978.

Alstom will be responsible for the refurbishment of turbines, speed governors and generators, and replacement of the excitation system. The company will be responsible for supervision, commissioning and supply of the transformer and instrumentation. Orteng takes charge of engineering, integration and supply of auxiliary electrical equipment, as well as supervision and commissioning. Camargo Correa will revamp hydromechanical equipment as well as dismounting and erection. The project will be completed by 2018.

The company has also been awarded a contract worth approximately EUR50 million by utility Hydro-Québec to modernise the Robert-Bourassa generating facility in Canada, bringing a substantial increase to the plant's efficiency.

Consisting of 16 units with a total power generation capacity of 5,616 MW, Centrale Robert-Bourassa is the world's largest underground generating station. The dam is located on the La Grande River in northern Quebec and one of the facilities of Hydro-Quebec's James Bay project. Together with the La Grande 2-A generating station, the two plants account for over 20 per cent of Hydro-Quebec's installed capacity.

Under the terms of the contract, Alstom will design, manufacture and deliver four new 333 MW Francis turbine runners for units 1-4 of the dam, and carry out the complete refurbishment and modernisation of two turbine-generator groups. Alstom will also supply several new components (ring gate, distributor, servomotors and turbine shaft) for unit 1 of the power plant, while refurbishing some of the existing components for units 2 and 3, and replacing 16 electronic governor systems. Commissioning of the first upgraded unit is scheduled for autumn 2013.

The contract also includes an option for the supply of four more runners for units 4-8 and the refurbishment and modernisation of six more turbine-generator units.

"Centrale Robert-Bourassa is strategically important for the province of Quebec and it is therefore a source of pride for Alstom to have been selected for this project. This contract further strengthens our long standing and excellent relationship with Hydro Quebec," said Jérme Pécresse, president, Alstom Renewable Power, and senior vice-president Alstom Hydro.

Wide ranging solutions needed

Genex Turbine Technologies has an established portfolio of solutions aimed at a broad range of customer needs. For example, when it comes to component repairs, the company uses state-of-the-art techniques to inspect and refurbish combustion, compressor and turbine section components manufactured by GE, Siemens (Fig. 1), Alstom, Mitsubishi and others. Genex staff have considerable knowledge in the repair of heavy industrial gas turbine components while a global presence ensures a quick response to individual needs.

The gas turbine component repair process includes a thorough inspection and detailed condition assessment. Metallurgical testing is often employed on components that exhibit material fatigue or have been operated near to or beyond OEM recommendations.

Genex is also able to recommend technical enhancements to components. And while replacement capital parts are very expensive, its REJUVINEX proprietary superalloy rejuvenation process extends the life of hardware and mitigates the risk of mechanical alloy failures in turbine airfoils.

Utilising its high-tech reverse engineering methods and manufacturing expertise, Genex has also developed and manufactured numerous after-market capital parts for customers. Currently, Genex is offering the following after-market capital parts: compressor blades, compressor stator assemblies, inlet guide vanes, shroud blocks, transitions, and combustion liners and baskets.

For its part Sterling Energy is dedicated to the professional management and maintenance of thermal and renewable power generation assets. Since its start in 1989 the company has added value for more than 120 clients on projects located in more than 20 countries. Its experience and management services span every phase of a power project, from development through asset management, and nearly every conventional and alternative energy technology.

Sterling is a specialist in developing operations and maintenance (O&M) management strategies, implementing management systems, recruiting and training plant personnel, developing policies and procedures, developing the annual operating plan and setting the culture to ensure project success.

When it comes to contract operations and maintenance, Sterling also provides all the personnel necessary to successfully commission, manage, operate, maintain, and administer the business and technical operation of the facility.

As part of this, it also helps to develop and implement generation equipment preservation and layup programmes compliant with or exceeding manufacturer's preservation guidelines.

International experience gains in importance

ESBI's O&M Solutions' expert team has extensive international experience in the operation and maintenance of power plants in Europe, Middle East and Asia.

This includes experience of conventional thermal plant (coal, oil, gas and peat fuels), open-cycle and combined cycle gas turbines, hydro, pumped storage technologies and wind farms. The company's experience also includes operation of base load, two-shift and peaking power plants.

ESBI's portfolio currently includes strategic operations and maintenance services to power plants in Spain, Northern Ireland, the UK, Malaysia, Pakistan and the Republic of Ireland.

Recently the company was appointed by NamPower, the Namibian state-owned electricity utility, to provide technical advisory services for the development of the 800 MW Kudu combined cycle power plant at Oranjemund on the Namibian border with South Africa.

The power plant will use gas from the offshore Kudu Gas field to produce electricity for Namibia and for export to the Southern African Power Pool (SAPP), an electricity market in Southern Africa

Economic growth throughout Africa is fuelling demand for electricity making this project a vital one for the region.

ESBI has a long track record in Africa having previously worked on projects in South Africa, Ghana, Kenya, Botswana, Malawi, Lesotho and Namibia.

The company is currently working on a four-year project in Tanzania which will significantly enhance the electricity infrastructure there and improve the reliability of electricity supply.

Billy Byrne, manager, ESBI Engineering Solutions, said: "Our relationship with NamPower goes back a number of years, and we are very pleased to have this opportunity to work with them again on this important project."

Recent Issues