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Towards the achievement of a stable electric power supply and a low carbon society
- Ohgishima Power’s efforts for increasing the efficiency and output of its existing gas turbines

Background: Achieving both eco-friendliness and high efficiency

Amid the liberalization of energy markets, energy companies are working to increase competitiveness by attaining both eco-friendliness and highly efficient power generation facilities.The power generation business supports the social infrastructure. In order to ensure a stable power supply, it is important to improve the availability and shorten the outage periods related to scheduled maintenance and facility construction and replacement work, aimed at not only for business perspective but also for fulfilling the social mission.

Hitachi provides energy companies with solutions for resolving their issues based on technologies and expertise accumulated through its abundant experience in the engineering design, construction and maintenance of power generation facilities.

Issue: Increasing the efficiency and output of existing gas turbines and minimizing outage periods

Ohgishima Power Station in Tsurumi-ku, Yokohama is run by Ohgishima Power Co., Ltd., a joint venture between Tokyo Gas Co., Ltd. and Idemitsu Kosan Co., Ltd. This power station generates electricity in gas turbine combined cycle power generation using natural gas with low CO2 emissions with excellent energy efficiency. It provides approximately 1,220MW of electricity, which is equivalent to the annual consumption of 2 million households.

Ohgishima Power was considering measures to further improve facility performance for stably supplying electricity to society and for evolving into a more competitive power station.Meanwhile, the available local transmission capacity was limited, and it was difficult to construct a new plant. The client wished to increase the output and efficiency of its existing gas turbines and those of the plant instead of constructing new power generation facilities.They also wanted to minimize outage periods for these replacement works.To meet their requests, Hitachi proposed a plan for gas turbine replacement during the period of scheduled maintenance to minimize the outage period.

Solution: Shortening construction periods by conducting replacement and scheduled maintenance concurrently

Hitachi delivered gas turbine combined cycle power generation facilities from Units 1 to 3 and their ancillary facilities for of the Ohgishima Power Station. Subsequently, it has offered comprehensive service including parts inventory management system under a Long Term Service Agreement (LTSA) to help achieve efficient operation and maintenance optimization at the power station.

This gas turbine replacement work was intended to address missions of increasing the output and efficiency, substantially prolonging intervals of scheduled maintenance by extending the life of hot gas parts, broadening the fuel combustion range to cover low-calorie shale gas and minimizing the outage periods due to work by replacing the hot gas parts of gas turbines in Units 1 to 3 with higher-performance, longer-life parts. However, it was so difficult that it would affect equipment other than gas turbines and required consideration of the whole plant. In addition, it was the first attempt to be carried out in parallel with scheduled maintenance. It was considered a very challenging project.

Hitachi made the most of its gas turbine engineering and construction technologies and its expertise in on-site operation developed through long-term maintenance work to pay the utmost attention from the planning stage and conducted close coordination with Ohgishima Power and overseas suppliers, and formulated an elaborate work plan and established an all-out project management structure.Given that this big project would involve hundreds of workers from both Ohgishima Power and Hitachi, they took all possible measures in terms of issues and efficiency and conducted rigid construction project management in a safety-first principle.

Normally, equipment replacement inevitably involves outage for at least one month. However, this replacement work was implemented in parallel with the scheduled maintenance of power generation facilities. As a result, it ended 11 days after the period of scheduled maintenance according to plan with no accidents or issues. The resulting increase in output and efficiency turned out to be larger than planned.

Future outlook: Increase in efficiency and contribution to realization of a low-carbon society

This replacement project was highly regarded by Ohgishima Power for attaining higher output and efficiency, extension of the life of hot gas parts to significantly extend maintenance intervals and compatibility with a wider range of natural gas with different properties.Hitachi will continue to support the operation of Ohgishima Power Station, which boasts eco-friendliness, high efficiency and profitability.In addition, Hitachi will propose digital technologies using Lumada in a bid to offer better services.

The energy market surrounding energy companies will become increasingly liberalized and maintaining a high level of competitiveness will be necessary for survival. Hitachi will use its technologies and expertise to respond to their requests, to contribute to a stable and efficient electricity supply and to achieve a low-carbon society.

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