EXPLORE THE POSSIBILITIES
Gas-planning for the unexpected
Open Grid Europe models gas flows through thousands of kilometers of pipeline to find answers
Answering the challenge of securing the gas supply in any event. Open Grid Europe (OGE) has modeled thousands of kilometers of pipeline and combined the data with their own acquired knowledge to design a safer gas infrastructure, all while preparing for an energy transition.
Like many of us in industry, OGE need to plan for the unexpected – in this case, any event that could disrupt the gas supply. For example, a customer might suddenly go offline or a power surge could trip in a compression station. Events like these could trigger disturbances in a highly pressurized gas network. OGE is one of Europe’s largest transmission system operators, providing sustainable energy to customers throughout Germany, and they need to plan for all kinds of risks so that the infrastructure will remain operational under any scenario.
The only way to be sure they can maintain the integrity of the pipelines through any emergency is to identify and mitigate the risks, so OGE aim to understand every scenario that could impact the gas supply network.
A large part of this work relates to understanding the condition of the infrastructure and assessing how well it will meet their energy needs in future. With the global focus on preventing climate change, there has been a shift in the industry to focus on improving gas pipelines to make them more efficient, also new suppliers are entering the market and there is pressure to reduce carbon emissions. OGE is investing in new infrastructure but they also need to monitor the older pipelines and know how easily they can be retrofitted to meet new requirements.
The key to solving these challenges is to understand the fluid flow through a network which is made up of many thousands of kilometers of pipes. Then with that knowledge OGE performs calculations relating to the performance of the networks and finds answers to a number of what-if scenarios.
Safety in all scenarios
OGE needs a reliable set of tools and methodologies to help their engineers understand the flow of gas within the complex network of pipes, so their team use Simcenter Flomaster to aid their understanding of the behaviors of the gas travelling through this huge and complicated infrastructure. Engineers can analyze detailed 1D models and see the results of various what-if analyses that could impact the network. Simcenter Flomaster’s post-processing capabilities allow the OGE team to gather useful results and insights from the data.
There is always a risk that an unusual condition might cause a build-up of pressure in one part of the network, and that could trigger emergency procedures that lead to a big increase in unplanned downtime. Naturally, it is best if these maintenance overheads can be avoided because they impact the steady revenue that flows from normal operations.
The engineers can keep a careful eye on parameters such as gas pressures, temperatures and specific concentrations, and monitor these at the points of metering and importantly all the way along the lengths of the pipes. Over time, OGE has developed their own ways to streamline the workflows and process the calculations which Simcenter Flomaster computes simultaneously for them.
During the ten years that OGE has used Simcenter Flomaster, it has helped them to prevent downtime and make their business operations more efficient overall.
Simcenter Flomaster’s graphical interface shows a small section of the gas supply network and models the effect of disturbances
Gas flow physics built in
OGE’s engineers use Simcenter Flomaster to simulate enthalpy-based vapor cycles so that they can study critical parameters under different scenarios and predict the behavior of the gas infrastructure under different conditions. For example, what would be the effect of a change in peak pressures?
Courant-Freidrichs-Lewy (CFL) gas flow parameters are built into the Simcenter tool ensuring that gas flow physics is fully addressed and thus provides faster calculations without compromising accuracy. OGE’s engineers are then able to use these calculations to assess the safety implications of changes to the infrastructure or their operational procedures.
OGE modelled a change that increases peak pressures fourfold. Would this make the entire system unstable?
Analyzing supercritical flows of CO2
OGE’s work goes beyond the day-to-day management of the infrastructure, they also plan for the future. The global shift towards more sustainable solutions and cutting carbon emissions has resulted in OGE engineers investigating emerging technologies that will be more sustainable, and planning for the transition to a greener energy supply. They are looking at the emerging use of hydrogen and technologies for carbon capture utilization and sequestration (CCUS).
Many industries, steel in particular, create large outputs of CO2. As Germany’s steel industry, which is mainly located in the Ruhr region, begins to move its CO2 output to offshore facilities where CCUS can be applied, the existing pipelines could be the way forward. However, the properties and behavior of CO2 are very different to those of natural gas so it is not immediately clear how well the existing pipeline network would support this requirement, or how they could transport the CO2 in the most efficient way.
These models show the supercritical phase region of CO2 where it is impossible to distinguish between incompressible and compressible flows.
These are questions that OGE will be able to answer with further research and investigation. There is a challenge and maybe an opportunity for the OGE team to leverage the benefits of this supercritical phase behavior for more efficient methods of transport in future.
OGE’s engineers can use Simcenter Flomaster’s enthalpy-based vapor cycle feature to model this and learn more. To find out what will be possible, it is essential to understand pressure-temperature-enthalpy distribution and phase split of carbon dioxide and how that would look across the entire network. Then the model would also need to consider the various points of generation, branching and merges, elevations and heat transfer in the network.
Simcenter provides answers quickly, even when the networks are large and complex, with hundreds and even thousands of kilometers of pipes and branches. OGE’s local partner, Smart-Fern, will continue to support their work of assessing the critical aspects of the existing gas infrastructure.
OGE is also interested in using online modules for operational planning. This could form part of a larger, IoT (Internet of Things) ecosystem that would provide real-time insights into the operation of the pipelines and their current condition.
Both OGE and Siemens share the wish to achieve safe and sustainable outcomes that are also financially viable for the energy supply. www.oge.net.