How an IIoT solution levels up thermodynamic processes
Grain CCGT Power Station is a 3 x 455 MW unit Uniper site based in Kent, UK. It consists of three natural gas-fired combined cycle gas turbine units capable of generating enough electricity to supply more than one million homes.
For Grain’s engineering and management teams, it is important to have an in-depth picture of asset health, predict and prevent potential failures and identify opportunities for improving efficiency and performance.
Enerlytics: The platform for dedicated experts
Uniper provides a solution for all the above-mentioned requirements: Enerlytics – an innovative, practical IIoT solution developed with top class engineering expertise. Power plants like Grain CCGT Power Station produce huge volumes of data – but making sense of it all can be a significant challenge. The untapped potential is remarkable. Enerlytics unlocks this for you by bringing your data together, analyzing it and presenting useful insights that allow operators to optimize the way their power plant is run. Its series of applications are based on many years of plant operation by experienced engineers and managers.
Thermodynamic Modelling – Giving insights, solving problems
Grain CCGT Power Station implemented Enerlytics in their workflow. Part of Enerlytics’ applications is “Thermodynamic Modelling”, providing thermodynamic simulations to enable engineers and operators to monitor the plant’s performance, at both individual component and overall plant level. It offers the flexibility to construct, modify, and analyze models using a wide range of modules, e.g. compressors, turbines or heat exchangers. Each building block consists of its own unique set of equations, covering performance, mass, and energy transfers.
Getting to the bottom of thermodynamic processes
Optionally, Grain CCGT Power Station can run in combined heat and power mode (CHP) – delivering a varying low-grade heat demand from the condenser to a local industrial site. The plant knew that the additional operational mode would only make it more challenging to track the overall performance of their seawater cooled condensers.
Condensers can have a big impact on plant performance and need to be clean and leak-free. Changes in condenser back pressure can be a sign of potential problems, but Grain’s unique operating scenario and their estuary-cooled condensers made this behavior more complex, with sea temperatures, unit load, CHP temperature and flow demands as well as any potential issues all playing a role in determining the back pressure.
Using Thermodynamic Modelling, the on-site engineers and the specialist performance engineers from Uniper began to explore the issue in more depth.
The team utilized a model of the asset, a thermodynamic twin, and monitored condenser performance live during operation. The model uses real operational data to characterize the performance of the plant. The characterized model is used to predict the performance of the plant for a wide range of conditions. In this example the target model of the unit was taken at full load and standard conditions. This target model was then compared with live operation to determine the impact of the current condenser condition on maximum generation and efficiency. To add to this, the team included additional monitoring through automated performance alerting, able to trigger an automatic email to site with recommendations to resolve the issue – another functionality included in Enerlytics.
If you identify the problem, you can solve it
In one example, the condenser performance monitoring solution identified a problem with the back pressure on Grain unit 7. The thermodynamic model identified a dip in condenser performance which was not immediately obvious nor quantifiable from the raw sensor data alone. The modelling identified the issue to be back pressure related, and likely related to something inhibiting heat transfer inside the condenser.
Without a model, the issue wouldn’t necessarily be obvious to the plant team as the rise in back pressure could have been at least partly explained by seawater temperatures naturally rising in the summer. The modelling was however able to correct for this and spotted a rise above normal conditions, indicating a problem with the condenser itself.
Playing catch-up in the US
“In Europe, offshore wind has been there for a number of years, but I think in the United States we're a little bit behind that,” said Karustis.
Should it be successful, Halo’s approach could lead to a surge in US onshore wind, which has historically lagged behind other regions in terms of wind installation and production. Since 2016, according to the International Energy Agency, the US has installed just 22.6GW of new onshore wind capacity, compared to 30.7GW in the EU, and 50.3GW in China, struggles that Karustis hopes to address.
Last December, the Chinese Government approved a number of new offshore wind projects, totalling 13GW of production and costing around $13.3bn, as the country continues to invest in utility-scale power. Karustis hopes projects like Halo’s distributed turbine can contribute to a more balanced wind sector in the US, with both large- and small-scale operations expanding renewable power.
“The large-scale wind turbines wouldn't be phased out, it's kind of an ‘all of the above’ thing,” he said. “The large wind farms play a very important role for us in reducing the carbon footprint globally, and hopefully the micro wind market is going to augment that by producing energy where energy is being used. It's a good two-pronged approach.”
This two-pronged approach also includes other renewable power sources, including solar and utility-scale wind; Halo is not trying to replace all clean energy with its turbines, but offer another option for people eager to engage in renewable power, who may have been historically sidelined due to the high costs of building utility-scale facilities or the unsuitable geographical characteristics of the places they live.
“When you look at that market we're very excited because just as megawatt-scale wind is a large market, I think distributed wind can be as big of a market or bigger over time,” said Karustis.
“When you have incentives and improvements in the technology, the costs go down, so you can be more competitive and compete, and that's certainly the case with megawatt-scale wind,” he continued. “Just 15/20 years ago, it wasn't competitive with natural gas [and] coal, but it is now. So those government policies have helped and they've driven the technology improvements, so it's all bundled together.”
Suit the action to the numbers – and get valuable results
Based on Thermodynamic Modelling analysis results, the maintenance team investigated the condenser during a planned outage. They found significant fouling coating the inside surfaces of the condenser tubes. This was reducing the effectiveness of the condenser and consequently causing the rise in back pressure, resulting in a peak electrical loss of approximately 3MW in just two and a half weeks.
Identifying the issue and cleaning the condenser enabled Grain to recover the losses, calculated to be up to almost € 4500 a day against ideal operation, recovering performance and preventing further problems such as tube blockages, or worst case a unit trip.
With support from Uniper’s specialist engineers and highly accurate models of their condensers, Grain was able to identify these issues, which would likely have gone unnoticed otherwise. Enerlytics’ applications offer a clear picture of asset behavior and are able to take into account a wide range of operating conditions, coupled with an automated alert system. By using these features to their advantage, Grain has been able to consistently identify and resolve condenser performance issues, making savings of circa thousands of euros a day across a range of examples.
Higher efficiency, more flexibility and deeper understanding with Enerlytics
Enerlytic’s Thermodynamic Modelling and advanced analytics enabled Grain to understand complex asset behavior in its condensers and compare this with target performance. This has helped them identify issues that would likely have gone unnoticed otherwise, prevent failures, optimize condenser performance and increase generation.
With Enerlytics, plant managers and operators are never more than a few clicks away from the complete picture. Presenting customer-built analytics on a single platform, the digital tool offers users the autonomy to optimize plant performance, and to make better, more informed decisions for improved flexibility and financial gain. Enerlytics maximizes the practical utility of power plant data, especially with its automated email alert function including recommendations for resolving emerging issues.
Uniper Technologies Ltd