Extending the Service Life of Turbines

The global gas crisis is affecting every industrial business, especially in sectors that are gas-dependent such as power generation. It is therefore important to make targeted decisions about which areas of the plant to invest in for the best outcome. With so much depending on the reliable and continued operation of the gas turbine, it is a strong contender, especially considering efficiency improvements, the increasing need for emissions reductions, and guaranteed availability.

Volatility in the energy market has had a major impact on the operator’s investment structure. The market was previously moving from baseload operations to achieving greater flexibility and efficiency, but now gas price volatility is having such an effect on performance that energy companies are reevaluating their business goals.

If the necessary supply-chain infrastructure is in place, units that were preparing to be moth-balled due to obsolete technology may be brought back into critical service. However, these older units will most likely require attention to bring them in line with current emissions standards, and their performance requirements may also need to be reviewed.

Navigating a Difficult Operating Landscape

All gas-fired power stations are required to meet national standards for emissions; any equipment that falls outside of these requirements can only operate for a restricted number of hours. With increasing demand, limited availability needs to be addressed, meaning operators with older units are now examining their supply chains to assess the viability of upgrade programs.

A large part of the existing gas turbine population has already reached the point where work is required to enable it to meet current regulations on emissions. For others, efficiency and reliability can be enhanced, but in many cases, the OEMs may be unable or unwilling to provide such packages as extending the equipment’s lifecycle, as they directly compete with their overarching strategy to install newer units.

In addition, any plans to add hydrogen to the natural gas supply will require new technologies to be implemented in power-generating sites. Operators are faced with numerous decisions in terms of the best way to invest in their equipment and ensure they continue to meet their obligations for supplying the grid.

These challenges and more add to the difficult operating landscape that power plants find themselves in. Moving forward, operators need to find an experienced engineering partner that can support them with cost-effective upgrade paths and enable them to keep pace with the changes.

Adapting Maintenance for Evolving Operations

Historically, gas turbine plants were built to work around the clock, providing a base-load energy supply. However, in today’s energy landscape, this model has changed, and the turbines are now acting as peak-load units, or standby units, requiring them to start and stop regularly to stabilize the grid’s demands. This change in operation influences the performance of the gas turbines and therefore the reliability and availability of the plant.

Taking no action on this change in operational mode could result in unexpected downtime. And, if the plant is unable to maintain the required output, it could be fined for failing to meet its energy obligations. Pressure is certainly increasing, and there is an opportunity for operators to resolve several challenges at the same time.

Several changes to the maintenance routines and design of the turbine itself should be considered in these situations, otherwise, the operation of the turbine may be compromised. The issue for the operator comes when the OEM only offers a minimal range of rigid solutions that may exceed the investment available at the time; at this point, an independent maintenance provider is required, one with sufficient experience, knowledge, and facilities to deliver the improvements effectively.

Sulzer carries out preliminary inspections and offers advice on the information provided. Credit: Sulzer

Consider the Individual and Their Surroundings

Each turbine should be assessed individually, accounting for its history as well as its current and future operational requirements. In some cases, the surroundings of the plant may have changed since the turbines were commissioned, and a revamp project could include modifications that improve efficiency and reduce emissions.

It is important to consider the infrastructure surrounding the power plant. For example, a generating site that is located close to a neighboring industry with a thermal demand or an area with district heating can be set up to gain maximum benefit from residual heat energy.

Similarly, a site located in an area that has an abundance of wind turbine generators may only be required to support the local grid during periods of low wind speeds and therefore less power to the grid. Such an operating model will differ considerably from a plant that is designed to deliver base-load power.

Pushing Beyond the OEM Upgrade Limit

To reach the expected design life of a turbine, OEMs work to the theoretical lifetime of the components and will usually only repair parts once. They must take a worst-case scenario and ensure their machine will remain reliable using the suggested maintenance intervals. However, this does not benefit every operator.

Sulzer carries out preliminary inspections and offers advice on the information provided. Credit: Sulzer

Working with the actual condition of the turbine and its current performance criteria is necessary—carefully assessing each component and deriving the actual lifetime of the turbine. This can be extended considerably beyond the OEM figures because the number of repairs can be increased while remaining well within the safety limits for the machine. Lifetime extensions can be achieved through modifications; for example, the application of specialized coatings that can extend maintenance periods.

The Repair Process

The process starts with a conversation that covers the history of the machine and what is expected of the turbine going forward. If the peak output can be reduced, the expected service life can be extended considerably, but this is not always an option. Modifications or upgrades are determined based on the technological advancements within the optimized cost structure for operations and maintenance.

Of course, the process is not as easy as just selecting any independent service provider (ISP). In cases where the gas turbine is insured, the insurance company will require assurance about the competency and expertise of the ISP. Any work carried out must be done to the highest standards, using the correct materials and procedures.

Volatility in the energy market continues to pose significant challenges for turbine operators, so they will need to change how their plants operate. The sooner action can be taken to improve performance, the quicker owners will see the benefits in terms of optimized output and extended service life.

Jan Jouke Melchers is the Business Development Manager at Sulzer, and Sebastian Boehmeis the Operations Manager at Sulzer.

Sulzer is a global leader in fluid engineering. It specializes in pumping, agitation, mixing, separation, and application technologies for fluids of all types. Sulzer has been headquartered in Winterthur, Switzerland since 1834.