Abstracts - VGB PowerTech Journal 8/2013

Failure mechanisms on low-pressure turbine blades

Martin Eckel, Stefan Thumm and Harald Pecher

In recent years, the AGCS and Allianz Zentrum für Technik focused on damage at LP turbines, particularly damage to blades. Erosive and corrosive effects are a key factor in addition to mechanical loads. In order to narrow down the root causes, it is vital not only to run a detailed lab investigation of damaged parts but also to verify natural frequencies, modal shapes, and stress distributions. A variety of test and repair measures but also operational adjustments are shown in the presented examples.

Reconstruction of the Leudelange refuse incineration plant with integration of existing plant parts

Harm-Peter Büchner and Uwe Jolas

SIDOR, a special purpose association for waste management in Luxembourg, manages the waste disposal of around two-thirds of Luxembourg´s entire population. E.ON Energy from Waste (EEW) participated in SIDOR´s tender process for both constructing as well as operating a new incineration line with an overall capacity of 150,000 t/a, which was accepted by SIDOR in October 2006. The new incineration line with an overall gross heat output of 67 MWth replaced the existing lines after completion.

Fire protection and right of continuance - A portrait with practical examples

Stefan Koch

Issues related to the scope of the conservation of the status quo of existing buildings are often not clearly settled. The owner of a building e.g. is not obliged automatically to use higher fire fighting standards of current legislation. However, from case to case, such adjustments might have to be made. Solicitors´ cases document how to enforce conservation of the status quo. Finally, legal reference is made to the relationship of conservation of the status quo, liability, and criminal liability.

Between the poles of architecture and fire safety

Georg Spennes and Gregor Jäger

Engineering methods of fire protection are to support planning and evaluation of a building concerning the risk in terms of fire protection measures and efficiency. There is no doubt that today’s usage concepts for buildings and constructions are only partly compatible with a literal implementation of building regulations. The introduction of the Eurocodes in July 2012 as a Technical Building Regulation can be described as a quantum leap in fire protection engineering. An example is given how to analyse fire loads thermally and mechanically.

Effective fire protection for turbines ensures high operational availability

Arnd Knop

Designing fire protection in power plants is extremely complex and related to different requirements from operators, insurers, and experts. High- and low-pressure water mist systems are increasingly used in turbine fire protection, as they have ideal properties for this type of application. There are multifaceted fire risks in the areas adjacent to a turbine. Therefore, an overall view of all protected areas is indispensable for effective and reliable fire protection. The paper provides a detailed look at the entire spectrum of possible fire protection technologies for turbines and their adjacent areas, describes functionalities and itemises the benefits of individual fire protection measures.

Fire behaviour of cooling tower packing

Tim Mattausch

The rapid burning down of the cooling tower of the shutdown power plant in Schwandorf revealed the potential of a total loss of a cooling tower in case of fire. VGB ordered a research project in order to obtain more knowledge about the fire risk of cooling tower packing currently applied. Depending on kind and age of the plastics used, the results of these tests manifest a big variation of the fire behaviour. For the applications of plastics, it is essential to determine and to adhere to organisational fire protection measures.

Explosion protection of fuel supply systems!

Jens Hötger and Stephanie Klose

Due to the flammability of the substances used, the risk of explosions cannot be excluded in the fuel supply system of power plants. In contrast to flam-mable gases and liquids, solid combustibles are normally handled in the presence of air. The fine portion of these combustibles is able to form explosive atmospheres. The use of imported coals requires reviewing the risk assessment of explosion protection. The use of biomass also requires detailed assessment of explosion risks based on the properties of the substances.

Planning and design of evacuation systems in fossil power plants

Lothar Marth

If, e.g. a power plant needs to be evacuated because of fire, minutes count. While the plant personnel is familiar with the local conditions including escape routes and gathering places, there will also be a lot of external staff at the site, e.g. during inspections. An evacuation concept must therefore take into account and also guarantee fast and reliable evacuation during inspections. Next to organisational issues and clear responsibilities, such a concept also must define a suitable combination of voice evacuation systems, tone alarms, and visual alarms, all of which must be specifically designed for the respective environment.

Cleaning technologies with sonic horns and gas explosions at the waste-fired power plant in Offenbach (Germany)

Tibor Horst Füle

During the operation of boiler systems, fouling (dirt, slag, ash, and soot deposits) appears to be inevitable in the combustion chamber and the flue gas path of power plants. The paper informs about the practical operating experience made in the waste incineration power plant in Offenbach with two not too well-known online cleaning technologies that can be easily retrofitted, i.e. acoustic sonic soot cleaning that can be used e.g. at air preheaters, economisers, catalysers and electrostatic precipitators, and explosion generator which is an automatic cleaning system that operates with controlled gas explosions to clean e.g. superheaters and evaporisers.

Basics about online boiler cleaning according to the Schwandorf principle

Jörg Krüger and Sascha Krüger

In the Schwandorf waste-to-energy (WtE) plant more than ten years ago a wet online boiler cleaning system was developed which has the capability to clean the radiation passes of (WtE-, biomass- and refuse derived fuel (RDF)) boilers without damaging the boiler. During the development it was recog-nised that the method of atomising the washing agent (water) is highly influencing the effectiveness of cleaning by securing parts of the boiler (mem-brane walls).

A new source of water that saves energy

Ludwin Daal, Hans Kamphuis, Frank de Vos, Martijn Huibers, Sjoerd van Rijen and Jacques de Ruijter

Water restrictions especially in arid areas are an increasing challenge for power plant operators. The use of selective membranes to capture water vapour contained in the flue gases could address this challenge. Such membranes offer a single step process capable of producing a large amount of water of high quality, virtually demin water quality that is non-corrosive. The process uses less cooling energy than otherwise would be required by condensing the entire flue gas stream. The European Integrated project CapWa (www.watercapture.eu) aims to produce a membrane modular system suitable for industrial applications.

Online soot cleaning using infrasound

Eric Torra i Fernandez and Martin Ellebro

The company Infrafone has been using infrasound as a soot cleaning method for more than 30 years. Infrasonic soot cleaning increases the efficiency, the availability and the lifetime of marine and industrial boilers. The properties and the description of infrasound and Infrafone’s soot cleaning method are presented. Moreover, a brief comparison with audible sonic horns is carried out. The results and the savings of installing Infrafone’s infrasonic cleaners are presented here with several case studies.

Assessment of creep rupture data of the nickel alloy 617B

Ronny Krein, Jutta Klöwer, Patrik Schraven and Vida Knezevic

Alloy 617B is an advancement of the standard Alloy 617 aiming on improved weldability and better creep behaviour especially for applications at tem-peratures below 800 °C. Against this background, Alloy 617B has been considered as a very promising candidate for the design of Advanced Ul-tra-Super-Critical power plants operating with steam temperatures of 700 °C or even above. However, results show that the creep rupture strength of Alloy 617B is superior to the classical Alloy 617; for higher temperatures the beneficial effect is negligible.