Joint project ECOFlex-turbo - Tranche 1

In order to do justice to the complexity and multitude of research tasks and project ideas, the programme was given a structure that assigns the topics to individual components of the turbomachine in so-called sub-compound projects. These sub-projects (TVP) are called Compression, Combustion, Cooling and Expansion. The challenges and technical objectives of the TVPs are closely linked to the requirements resulting from the boundary conditions for the successful implementation of the energy transition and have an impact on new and existing plants in the fossil-fuelled power plant fleet in Germany:

Sub-project compaction

The energy transition with its lasting changes in the power generation market results in significantly different operating requirements for thermal power plants with new and additional challenges for compressors. More robust compressors that achieve a high degree of efficiency over the widest possible operating range are required for high operating flexibility with very fast and, if necessary, frequent load changes. Further developments are being sought, particularly in the area of operating flexibility and increased service life with short operating cycles, which will lead to a robust compressor design. Operation-induced service life determination must be expanded and, building on this, efficient technologies for measures to increase service life must be developed. The technological issues relating to compressors continue to focus on increasing efficiency, especially partial load efficiency.

Sub-project combustion

The ECOFlex-turbo programme will focus much more intensively on load and fuel flexibility with a view to the energy transition, without losing sight of increasing overall performance. Gas turbine plants will play an even more important role in stabilising electricity grids in the future. Compared to today, there will be a massive change in the requirements profile in terms of load and fuel flexibility of the combustion chamber. This poses considerable challenges for combustion technology. Even at extremely low loads, with low flame temperatures and mass flows in this operating state, the emission limits (e.g. CO) must be complied with and extinguishing prevented. Load-following operation with high power gradients places considerable demands on the thermoacoustic stability and controllability of the combustion system. As the highest temperatures of the gas turbine also occur in the combustion system, start-up and shut-down processes lead to considerable thermocyclic stress on the materials. It can also be assumed that the fuel basis for gas turbines will become increasingly diversified. Liquid gas, biogas, blast furnace gas and synthesis gas require increasingly broader fuel specifications. Hydrogen - also as a storage medium from renewable energy generation - requires the gas turbine to be able to handle hydrogen-rich or, ideally, fuel gases with significantly varying hydrogen content in one and the same combustion system.

Sub-project cooling

The high process temperatures and pressures necessary for high efficiency require components made of high-temperature resistant materials for technical realisation in the area exposed to hot gas. In addition to the further development of materials with high temperature stability, the development of suitable cooling methods has played and continues to play a central role. Over the past 20 years, this has made it possible to achieve an increase in the application temperature of well over 500° C to date. Today, the hot gas temperatures are significantly higher than the melting temperatures of the metallic materials used. The aim in the development of cooling technologies was and is to minimise the cooling air used in order to achieve both the high process pressures and temperatures required for thermal efficiency and to minimise parasitic losses.

For future applications of the gas turbine process, flexibility, i.e. fast load changes and rapid start-up and shutdown, will become increasingly important for the reasons already mentioned. The service life of the components exposed to hot gas is essentially determined by the maximum mechanical loads and the component temperatures and their gradients, in addition to the cyclical load caused by start-up and shutdown processes. These temperature gradients in turn depend directly on the load cycling operation. Optimising the cooling methods and their design is therefore an important prerequisite for the environmentally friendly and at the same time economical operation of gas turbines in highly cyclical operation, also with a view to maximising the service life. These topics are to be given high priority in the new ECOFlex-turbo programme.

Sub-project expansion

In the ECOFlex-turbo integrated programme, the aim is still to further increase the efficiency of the turbines while optimising costs at the same time. At the same time, the turbines must be designed with higher permissible load change numbers and load change speeds in mind in order to be able to compensate for the fluctuations caused by the fluctuating feed-in of wind and solar power. The focus here is on optimising integration into the energy generation environment, which is increasingly characterised by renewable energy converters, through new developments.