Efficiency the target for maintenance and repair

Paul Boughton

When it comes to overhauls, repairs and replacements, power generators are focusing on solutions that can offer improved efficiencies. Sean Ottewell reports.

Alstom Thermal Services in Mexico has been awarded a contract worth close to EUR7m for the rehabilitation and upgrade of the main electrical equipment of unit 4 at Comisión Federal de Electricidad's (CFE) combined cycle power plant El Sauz in the Mexican state of Queretaro. The modernisation includes a refurbishment of the steam turbine generator rotor and the modernisation of the generator circuit breaker.

The project of upgrading the electrical generator is the first of its kind in North America using the pre-manufactured, winded stator insert technology. The use of this technology reduces servicing time on the equipment by approximately 50 per cent. Once upgraded, the generator will optimise start-up times and further increase the reliability of the plant.

Alstom is also retrofitting the steam turbine and replacing three older gas-turbines with a single GT24 gas turbine at the power plant. All of these works will add at least 25 years to the plant's lifetime and increase its efficiency by 20 per cent.

The company has also secured an order worth approximately EUR90m from the East Delta Electricity Production Company (EDEPC) for the supply of equipment for a 650MW steam cycle thermal power plant at a site located in the vicinity of Suez city, 150km east of Cairo, Egypt.[Page Break]

The plant will directly provide electricity to more than half million people residing in the Suez city district and will also be connected to the national grid. It will be commissioned in 2015.

The scope of the contract includes engineering, manufacturing, erection and commissioning of the steam turbine and generator, including auxiliaries such as the condenser and the delivery of spare parts.

EDEPC provides electricity for the eastern part of the country from areas around the Mediterranean city of Damietta up to Egypt's southern border with Sudan.

Alstom has previously supplied maintenance equipment to EDEPC for its Damietta combined cycle and the Attaka steam power plant projects (Fig. 1).[Page Break]

Alstom's total installed base in Egypt is approximately 4.5GW, having supplied its power generation equipment to projects such as the Abu Quir, El Tebbin and Sidi Krir steam power plants and Cairo North, Nubaria III, Kureimat and Talkha gas-fired plants.

In other company news, Alstom Thermal Services business in India has secured a contract worth close to EUR53m for renovation of gas turbines at NTPC's 657 MW Jhanor Gandhar Gas Power Station Stage-1 project located in Jhanor in Bharuch district, Gujarat, India. The plant was originally supplied with Alstom's GT13E1 gas turbines.

The scope of supply involves gas turbine components, installation, testing, commissioning and conducting a guarantee test of the gas turbines after replacement of their components.

While the components will be manufactured in Alstom's global state-of-the-art manufacturing facilities, services will be provided by Alstom's Thermal Services business in India. The project is scheduled to be commissioned over the next three years.

"The winning of this contract is a testimony of Alstom's advanced technological capabilities and expertise in gas turbines services in India. Alstom has strong references in this segment and is fully geared up to successfully execute this important order. Alstom is committed to provide efficient and reliable power generation technology to fuel India's economic growth and enable continuous and sustainable supply of electricity to its growing population," commented, Francois Carpentier, vice president, thermal and renewable power, Alstom India.[Page Break]

Wood Group GTS has been awarded a multi-year rotating equipment managed maintenance services contract for the Brent Assets of Shell UK. This award provides comprehensive support services for power generation packages and follows the establishment of an enterprise framework agreement (EFA) last year between the two companies.

Shell UK's Brent field has four large platforms: Alpha, Bravo, Charlie and Delta. Wood Group GTS was selected as the preferred service provider after executing a gas turbine power generation package restoration project on Brent Charlie platform.

Mark Dobler, ceo Wood Group GTS, said: "Our success is driven by careful alignment of our goals with those of our customer and by engineering specific solutions to mitigate risk and optimise performance of our customer's assets. By taking an integrated approach to managed maintenance services, we are committed to help Shell UK achieve their objectives in the most effective and efficient manner. We're delighted to have been given this vote of confidence by Shell UK and will continue to nurture and grow our relationship by delivering on these commitments."[Page Break]

The company has also secured an exclusive term maintenance agreement with Maersk FPSOs to support multiple Siemens gas turbines operating on their Curlew and North Sea producer floating production storage and offloading (FPSO) units. The contract duration is five years.

Maersk's FPSOs operate in some of the most demanding environments in the world and must deliver outstanding performance. The Curlew and North Sea Producer FPSOs were developed to meet the specific requirements of the UK continental shelf and operate under sometimes very challenging conditions.

This award encompasses planned and unplanned maintenance activities on six Siemens gas turbines including two TB5400, two SGT-200 (Tornado) and two SGT-100 (Typhoon) engines. The comprehensive work scope includes field services, technical support, repair and full engine overhaul services.

Tom Sanders, procurement manager of Maersk, stated, "Gas turbines operating on our North Sea assets provide a vital source of electrical power that's essential to the successful operation of our FPSOs. We selected Wood Group GTS based on their ability to provide a total support package and the transparency of their business process."

"We recognise the importance oil and gas customers place on the reliability of their production assets and the need for suppliers to demonstrate a robust support service capability to maintain process critical equipment" said Iain Murray, oil gas and industrial services president of Wood Group.[Page Break]

In a third new development, Wood Group GTS has been selected as the service provider for a EUR775,000 combustion inspection contract on a GE Frame 7EA dual fuel gas turbine at a power generation facility located in Kansas. Under the contract, Wood Group GTS will provide a complete solution for major maintenance services including field services, component repairs, provision of DLN-1.0 (dry low NOx) combustion parts and controls tuning.

"We understand the importance placed on power plant availability. Wood Group GTS maintains an extensive inventory of parts, enabling us to meet most requirements from stock. The holding of critical spares is one aspect within our portfolio of products and services designed to increase the overall value of services for gas turbine operators," said Frank Avery of Wood Group GTS Power Plant Services. "We are able to greatly reduce the capital requirements for our customers while also decreasing lead time and outage duration. All of these attributes contribute to increasing the return on the investment our customers make in gas turbine technology."[Page Break]

Component repair

The repair of individual components and their return to serviceable condition is also important in maintenance regimes.

IMS performs such repairs, the aim of the company's repair procedure being to restore the design service life of the component. Each item refurbished carries the normal company warranty, being guaranteed for a 12-month period.

Typical components that can be repaired include compressor blading (rotor and stator), combustion system components (swirlers and flame tubes), rotor shaft journals, abraidable labyrinth seals, and turbine hot blading (rotor and stator).

The repair procedures offered include welding, brazing, coating and re-forming, together with a variety of non-destructive testing techniques.

While industrial gas turbines have traditionally been designed for servicing on site, their increasing sophistication means that this is not always desirable or practicable. For this, IMS uses its turbine overhaul facilities in Inverurie, Scotland.[Page Break]

Continuous improvement is key

Irish gas turbine maintenance and repair company Shannon Power Management Limited (SPML) believes that a philosophy of continuous improvement is the key to success.

So the company actively encourages regular evaluation and development of those areas where improvement is considered feasible, plus a maintenance service that is highly engineered to meet the clients' requirements

SPML offers a full and comprehensive service and support to gas turbine, steam turbine, CHP and cogeneration facilities. These services include advice from specialists on day-to-day operations, routine inspections, overhaul and unplanned maintenance services, plus ongoing operational services.

Areas covered include operation and maintenance, plus technical field services to the power generation, oil and gas, industrial-process and renewable energy sectors worldwide. The company has substantial experience in the energy industry, including engineering, project management, construction management, planning and energy management.

In terms of services, SPML can scope, project manage and deliver: borescope; planned maintenance; combustion inspections; turbine compressor inspections; electrical inspections; performance testing; hot gas path inspections; reliability testing; vibration analysis; and validation.

These services are fully supported by SPML in-house specialists. SPML assists with planning the necessary services to align with each individual client's business strategy and will supply quality personnel to carry out the work to the highest standard.

Company specialists audit and assess day-to-day routine inspections which are currently being undertaken and/or planned by the operator and make cost effective recommendations.

The company also offers clients an emergency repair service. Using in-house capabilities, its specialists can rapidly establish the requirements necessary to bring facilities back to full operational capacity.

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