Abstracts - VGB PowerTech Journal 4/2014

Offshore wind energy – status and perspectives

Holger Gassner

Offshore wind power belongs to those renewables technologies, which increased tremendously in recent years and with a high potential for further growth. Offshore wind energy can be utilised at high full load hours and is therefore an important part for the future energy system and the growth of renewable energy. By realising a huge potential for cost saving, wind power economy will increase in the future.

Challenges for pumped-storage power plants in the current European context

Karl Wimmer, Markus Pfleger, Roman Derungs and Thomas Kunz

Rapidly increasing power generation from renewable energy sources, further extension of the power grid and sufficient storage capacities are representing the three pillars of the turnaround in energy policy (Energiewende). Pumped storage is currently known as the most economical method of large-scale power storage and its development potential for further expansion of capacities is definitely available. Yet the significant reduction of margins impedes the realisation of new projects.

Opportunities for dual energy supply after 2020 even during calm wind conditions and minimal solar radiation

Ernst Welfonder

Starting from hourly-based power measurements, a realistic extrapolation is performed concerning the future fluctuating feed-in of photovoltaics and wind parks in Germany. Based on t hese findings, a size-sor ted frequency distribution serves to demonstrate the extent to which the remaining power plant park – after the planned power plant dismantling – will be able to contribute to load covering. The required dual energy supply can probably be covered until the end of the 2020ies by the power plant park still available at that time as well as by pumped storage hydro power stations and load management measures.

State of the art of the conversion and storage of electrical power

Nina Hack, Simon Unz and Michael Beckmann

Due to the high ratio of fluctuating energies (FE) in electricity supply, there are already moments of spill-over load and grid overload with rejection of electricity from wind and photovoltaic (PV). Even with a further rising ratio of FE in electricity supply, the maximum residual load, which still occurs at low wind and PV emergence, remains at an almost constant load level. Germany needs storages for hours, days and weeks, so that the load deficiency can be covered without keeping all fossil power plants in operation and that the spillover load can at least partly be used.

Full-scale CO₂ post-combustion capture in an ultra-supercritical coal-fired power plant: an integral evaluation of capture plant configurations and heat integration options for minimising the energy penalty

Guido Magneschi, Cristina Sanchez Sanchez, Ana Matic, Gerard J. Stienstra and Earl L.V. Goe-theer

Post-combustion CO₂ capture is a key technology for reducing power plants CO₂ emissions, how-ever, current post-combustion capture technologies have a large impact on power plant operation and electricity costs. This penalty can be minimised with an optimum combination of solvent system and capture process configuration. The energy penalty can be further reduced by optimising the heat integration between power plant and capture plant. The work presented in this paper evaluates the energy performance of several cases where the most interesting options have been combined together.

FGDplus: further development of the conventional wet FGD technology

Andreas Gruber-Waltl, Christian Baumann, Michael Kramer, Harald Reissner, Knut Stahl and Christian Weiß

The reasons for process development in the field of flue gas cleaning technologies are no longer restricted to more stringent countryspecific emission limits. Meanwhile, there are other reasons, such as optimisation of the separating efficiency in order to improve input of energy and resources. Another determining factor is the need to minimise the maintenance effort over the entire lifecycle of a flue gas desulphurisation plant. A new type of FGD technology, currently being developed and based on the proven limestone scrubbing technology, meets these new requirements.

Hydrogen “co-firing” in a sequential combustion gas turbine: an opportunity to enhance renewable energy output

Torsten Wind and Allesandro Scapato

The progress in installation of renewable energy from e.g. wind turbines or solar panels, and the associated increase of electricity grid instabilities, requires the development of energy storage systems and the installation of flexible backup power for matching supply and demand of electricity. Hydrogen (H₂) standalone or blended with natural gas (H₂ co-firing) is a flexible and clean energy carrier for short and long-time storage. This article shows the advantages of a sequential combustion system, which can be found in an ALSTOM GT24/ GT26 gas turbine, especially regarding operation with H2-doped natural gas.

High-temperature SCR on coal-fired boiler

Luca Spagnolo and Virgilio Guerreiro

Applications of SCR for NOx emission control have begun to focus on the SO₃ issue since SCR catalysts may be responsible for additional SO₂ conversion to SO₃ in the flue gas. At Sines Power Plant (Portugal), Alstom Power retrofitted four 314 MW boilers with SCR plant designed to control the nitrogen oxides emission in the flue gases with temperature up to 425 °C at MCR. Several tests have been conducted on laboratory and field to measure the SO₂ conversion of the catalyst.

Optimisation of the cyclone separator of a circulating fluidised bed boiler – theoretical background and operating experiences

Christoph Ipsen, Dirk Roschek and Ulrich Muschelknautz

The municipal utility Stadtwerke Flensburg GmbH operates three circulating fluidised bed (CFB) boilers (boilers 9, 10 and 11), which are almost identical in design. Over the years numerous modifications have been made to the steam generators which caused trouble to the furnaces: one boiler could no longer be operated at full load. In order to ensure troublefree operation, the separation efficiency of the cyclone separator has been improved by installing an eccentrically narrowed vortex finder with swirl vane inserts and a barrier in the inlet duct.

Additives as method for preventing fouling – results of large-scale tests

Henryk Kubiczek and Sylwester Kalisz

The utilisation of biomass as renewable source of energy causes increased operational costs. This is mainly due to the physical-chemical properties of biomass on the combustion process and the combustion system. The higher the share of biomass in the total fuel stream and the worse the quality of such biomass the more problems appear. Among the main problems is the process of intensified slagging and fouling of boiler heating surfaces which limits heat transfer, changes flow conditions and generates numerous operating problems. The paper presents results of on-site tests of two additives intended to counteract ash deposits in biomass co-firing boilers.

Boiler casing measurements in a power plant

Reiner Krogbeumker

Upon firing of coal in a power plant boiler various factors have to be observed. Environmental protection and the compliance with emission limit values in flue gas are substantial criteria. The control of NOx emissions, however, is accompanied by corrosion damage inside the boiler resulting from the combustion process. That decreases the availability of the plant due to shutdowns for repairing and produces costs for reconditioning. Processes can be optimised and the reliability of the power plant’s operation can be increased. The paper shows an approach at the example of the hard coal-fired power plant of E.ON in Wilhelmshaven.