Abstracts - VGB PowerTech Journal 6/2020

The Show must go On-line

Nigel Blackaby

Since the start of the global Coronavirus pandemic, most businesses have experienced a pretty dramatic change in their fortunes. While an exceptional few, like supermarkets, online retailers and entertainment streaming services, have prospered from the crisis, the major-ity have experienced, at best a lean time and, at worst, a real battle for survival. [more...]

Dependence of the Federal Republic of Germany on energy imports

Hans-Wilhelm Schiffer

The German energy supply is – in comparison with most other G20 countries – to a larger extent dependent on imports. Domestic production of lignite, crude oil and natural gas has decreased significantly in the past decades. The mining of hard coal was completely stopped at the end of 2018. The tenfold increase in the use of renewable energies since 1990 has dampened the increase in the import quota. Nevertheless, the import dependency increased from 58 % in 1990 to 72 % in 2019. Renewable energies will continue to grow. However, the supply of hydrogen and synthetic fuels is likely to be made predominantly through deliveries from abroad. The high import quota for energy supply will hardly change in the future, even if the PtX strategy is successfully implemented.

Control of component fatigue in flexible power station operation
Realistic mapping of fatigue in components exposed to cyclic load

Franz Binder

As the output of renewable sources of energy is inevitably volatile, massive fluctuations in energy feed-in must be offset to ensure grid stability. To do so, thermal power stations are operated more flexibly. However, this exposes pressurised components to higher loads, which in turn increases the risk of failure and unscheduled plant shutdowns. On the other hand, many plant managers with an eye to the cyclic loads acting on components are uncertain whether operations can bear greater flexibility. Given this, operators need a method that realistically maps component fatigue in past operation, to enable them to take early countermeasures without being forced to act too early by theoretical fatigue values calculated at unrealistically high levels. An ideal method allows reliable forecasts to be made for future operations and proposes a suitable mode of operation, which enables the fatigue reserves of the relevant components to be utilised without compromising on plant safety and availability.

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Steam turbines: old iron or innovative component for the energy turnaround ?

Christian Scharfetter and Kristin Abel-Günther

Electricity from renewable energy sources save fossil fuel resources and reduces CO2 emissions from power generation. This is a sustainable improvement for our environment and limit climate change. Wind and solar power are dependent on the season and the weather conditions, do not offer sufficient security of supply and lead to fluctuations in generation. Biomass, waste incineration plants and conventional gas-fired power plants are already able to provide reserve power quickly and contribute to grid stability. It can be stated that the steam turbine technology, which is over 100 years old, can and must continue to make a decisive contribution to the functioning of the energy networks in the future in order to operate them in a stable and reliable manner. Tomorrow’s steam turbines have digital diagnosis and maintenance systems, operate with different operating media at the limits of material loads in steam generators and turbine blading and shaft sealing systems, are linked to each other via intelligent grid feed-in controls and are controlled by higher-level systems. They are used for energy conversion in a wide variety of thermal power plants. Waste incineration plants and biomass power plants are increasingly supplemented by thermosolar power plants, microgrids and storage power plants with cooling and heat conversion.

Stand-by mode for Frimmersdorf P/Q: Training programme for operating staff

Georg Bung, Dominik Palme, Rolf Hopf and Horst-Günther

In the years 2016 to 2019, lignite fired power plants with a total capacity of 2,700 MW are transferred, each for 4 years, to stand-by operation and then will be decommissioned. Apart from ensuring the plants are technically ready for operation by introducing mothballing measures, controls and test runs as well as maintenance and repair activities derived from them, there is also a big challenge of keeping alive the specific plant and process know-how of the operating staff. To preserve the acquired know-how and experiences, a tailored knowledge database had been developed before the stand-by operation began which provides all important information concerning the plants and in particular the procedures during start-up and normal operation of the units in a clear, practical and quickly accessible manner. Based on this knowledge database, a training programme was developed together with the power plant school “Kraftwerksschule e.V.” in order to ensure that an excellently prepared team is immediately available. In this programme, all procedures are discussed with the employees and as far as permitted by the mothballing measures, practised in applied exercises.

Failure analysis for evaporator fin-tubes of HRSG in CCGT

Hong Xu and Zhi-hao Tian

The finned water-wall tube of medium pressure evaporator leakage occurred after the no. 1 unit of a combined-cycle gas turbine (CCGT) power station was put into commercial operation for only 40 days (including 24 days of operation and 19 days of shutdown and standby). Cut off a section of failure pipe for a thorough inspection. Macro inspection found that severe corrosion occurred in some local areas of some pipe sections, which led to the obvious thinning of pipe wall thickness, leading to perforation and leakage. The inner pitting corrosion of fin-tube of evaporator in HRSG could be avoided as long as the relevant provisions of “Guidelines of chemical supervision for combined cycle power plants” (DL/T 1717-2017) were strictly implemented during normal operation of boiler, standby maintenance and water pressure test after overhaul.

Run-of-river hydroelectric plants as providers of balancing energy? Potentials of dynamic upstream reservoir levels in case of the research-plant in Bannetze-Hornbostel

Bastian Hase and Christan Seidel

Growing shares of fluctuating renewable energies, such as wind and photovoltaics, make predictable power generation capacities more and more important. What is more, the decarbonization of the energy sector creates a growing a need for renewable balancing energy technologies as substitutes for conventional capacities. Simulations conducted for a projected research plant in Northern Germany showed that run-of-river hydroelectric (ROR) plants can deliver both, constant load and balancing energy, at the same time when using their upstream reservoirs as a short-term storage. For most plants this is feasible since their upstream water levels can, to a certain extent, be flexible, without making further impacts. When upscaling the balancing energy potentials of the simulated plant to the whole German non-swelling ROR-hydropower, significant amounts of the yearly national demand for balancing energy could theoretically be covered. These potentials, however, depend on the type of balancing energy provided and on the chosen lead value for the upstream reservoir level between the minimum and the maximum flexibility limit. In economic respects, investigations for automatic frequency restoration reserve revealed that despite a lower overall energy production additional income can be generated, depending on the amount of control energy produced and the strategy used during the power auctions.

Power to Gas - why actually not yet? An update

Albrecht Pfaud

While electricity by wind &sun is subject to variations of weather, it is defined as “volatile”, means it is sometimes available more than necessary, sometimes less or even not at all. One possibility to save the overload of energy is the transformation Power to Gas (PtG). Hydrogen may be delivered to the general gas network or sold to industry as a basic material. Nowadays, in Germany, there are about 30 plants for electrolysis either existing or in planning. As one will see, the potential of volatile overload is far less than the demand for industrial hydrogen. Therefore, the legislator should cancel the above mentioned §15 in order to increase cheap volatile electricity. Finally, some other desirable legal modifications will be discussed.

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A journey through 100 years VGB | The 1950ies

  • 30 Years VGB
    R. Hoffmann
  • The competition between heat engines
    E. Sörensen
  • Summary of the VGB General Conference 1956
    R. Quack