Abstracts - VGB PowerTech Journal 11/2010

Latest Development in Power Plant Technology Carbon Capture and Storage (CCS) Can it be a Solution for the Future?

Reinhardt Hassa

The worldwide CO2 emissions have to be decreased to stop climate change. It is both the chance as well as the commitment of the electricity industry to shape the future by working on innovations and technologies that will lead the way. This goal can be achieved when we continue developing our energy mix of renewables, nuclear energy and CCS technologies. We also have to improve our energy efficiency. Dealing with CCS technologies, it goes without saying that a technology not fully researched yet also raises questions. Vattenfall demonstrates with its roadmap and its projects the progress made in the development of CCS technology.

Particular Characteristics of Firing Systems in Oxyfuel Steam Generators and Effect on Design and Operation

Thomas Wild, Steffen Lysk, Frank Kluger and Helmut Bischoff

The oxyfuel process is a process variant for the separation of CO2 during the combustion of fossil fuels. The advantage of the oxyfuel process is that the water-steam cycle and the steam generator do not differ significantly from conventional coal-fired power plants. What is new, however, is that an oxyfuel steam generator - owing to its process management - provides more degrees of freedom for the design of the firing system than an air-fired boiler. The design of future oxyfuel steam generators is based on the proven technology of existing conventional coal-fired power plants, theoretical considerations for oxyfuel combustion and the experience from the planning and operation of the 30 MW oxyfuel research plant in Schwarze Pumpe.

Intuitive Operator Guidance Supported by Process Visualisation

Martin Hollender, Dirk Stevens and Kati Langlotz

Human beings are bound to be the essential decision-maker in the control room and therefore indispensable. In order to support the operator in case of an important incident, to take corrective actions and make the right decisions, the information is to be presented in such a manner which makes it possible to ease problem-solving. Therefore, it is of prime importance to install various measures early in project planning to assemble a reasonable alarm system, and later in continuous operation to improve it as well. With it and in combination with new display types a process visualisation providing intuitive operator guidance is put into practice.

Mega Components Made of Cast Steel for Power Technology

Reinhold Hanus

The foundry-group of voestalpine with the Austrian locations in Linz and Traisen, produces heavy cast steel components for numerous power plant applications. A weight class between 1 and 200 tonnes can be produced in the foundry group. Each of these markets has its own specific challenge. This paper refers to the speciality, which a steel foundry for heavy parts has to manage in the section of the steam generating plant. We especially want to show this on steam turbines for power plants in the highest operating level (up to 1600 MW).

Recommendations for the Inspection of Turbine Generators

Ulrich Groß and Jörg Emmerich

The publication deals with the 2nd edition of the VDEW Guideline "Recommendations for the lnspection Intervals of Turbine Generators" and takes account of the further opportunities presented by the currently available monitoring and diagnosis systems. Examination methods relevant to various generator components are presented in relation to the various types of inspections. The recommendations for inspection intervals already published in the VDEW Guideline are modified in relation to the influence of on-load operation time, turning gear operation time and the number of starts, in accordance with experience gained and new developments. Furthermore, additional influencing factors on load changes and weaknesses dependending on design or age are proposed. The weaknesses analysis is based on the evaluation of a generator damage database maintained by VGB comprising mainly European power plant operators.

Major Steam Turbine Losses - Causes, Repair Measures, Recommissioning

Stefan Thumm, Martin Eckel and Rüdiger Beauvais

Major damage on main steam turbine components does not necessarily require replacement of the damaged components. With the application of respective engineering and manufacturing resources a preliminary or final repair can be realised considering the damage causes and therefore preventing repeated damage. Most important, however, is the qualification and experience of all parties involved. The common interest is to keep balance between costs, time requirements and risk.

Model-based Process Management and Process Optimisation of Industrial Steam Generators

Wolfgang Kästner, Rainer Hampel, Tom Förster, Matthias Freund, Dietmar Haake, Heiko Kanisch, Ulrich-Steffen Altmann and Frank Müller

Within the framework of a joint project sponsored by BMBF the development of algorithms for the optimal process management of industrial steam generators was carried out. The research work was focussed on the reduction of high-temperature corrosion at the membrane walls of lignite-fired steam generators. In the result a system for demonstration of technology was installed successfully in a Vattenfall power plant in 2009. During the operation of the power plant the capability of the system to guarantee a stable and symmetric fire position was demonstrated. Current work is focussed on the further development and retrofitting of the system to apply it under real condition in a Vattenfall power plant.

Condition Monitoring, Diagnostic and Controlling Tool for Boiler Feed Pump

Sohail Ahmed, Reinhard Leithner and Günter Kosyna

The boiler feed pump is an important component of a thermal power generation cycle and demands high safety and unquestionable availability for flexible power plant operation. In this research paper, the methodology of a general purpose condition monitoring, diagnostic and controlling tool is presented, which can address the challenges of operational safety and availability as well as optimal operation of a boiler feed pump. This tool not only effectively records the life time consumption of both casings and rotors and monitors the small gaps between casings and rotors but also suggests appropriate actions in order to ensure that the pump operates within the allowable design limits.

Weld Repair of a Cracked LP Rotor

Andreas Nowi, Klaus Herzog, Sorin Keller and Thomas Michalski

In the West Power Station unit 2, rated at 350 MW consisting of a condensing turbine of MAN design commissioned in 1971, a significant continued increase of shaft vibrations was noticed. Therefore, the turbo set was shut down in order to systematically investigate the root cause of the vibration increase. A weld repair solution was developed during which a new rotor front end was welded to the original truncated rotor body. Details about the damage pattern and root cause as well as repair solutions and repair process including attained welding quality will be presented in this report.

New Ways for Raising Pulveriser Output at the 600 MW Units in the Weisweiler Power Plant

Bernhard Röper, Alex Knobloch, Thomas Krause and Tieu Le Van

Over the years load restrictions occurred more frequently at the G and H units in the Weisweiler Power Plant caused by a limitation on pulveriser output on account of deteriorating fuel properties. The output was to be raised by reducing the internal pressure drop and/or flow resistance in the pulveriser - instead of raising the pressure build-up. Thanks to the comparatively low investment costs, raising pulveriser output is now a paying proposition even for those installations which are to be decommissioned in a few years.

Xwin® - New Technology to Increase Lifetimes of Wear Parts for Vertical Roller Mills

Oswald Velz and Franz-Josef Hülsbusch

With the Xwin®-technology, it has been possible to substantially increase the lifetime of wear parts in vertical roller mills. This composite material, a combination of high-chromium white iron reinforced with ceramic particles, reaches lifetimes which are in the range of three times higher than ordinary high -chromium castings. With greatly improved lifetimes compared to the above-mentioned materials, total costs for wear parts are reduced and maintenance intervals of wear part replacement are substantially increased as well. The typical wear profile generated by this technology results in a grinding process improvement such as a higher mill throughput or better grind.

Flame Investigations of Coal and Biomass Combustion with a 35 MW DS® Burner and Modification for Indirect Firing

Tanja Weirich, Alfons Leisse, Jürgen Niesbach, Christian Kuhr and Hans-Joachim Koczorowski

Based on experimental flame investigations the capability of a DS® burner to operate in a wide load range with different fuels was verified. A DS® burner with a thermal capacity of 35 MW was installed in a combustion test facility in order to perform in-flame ash sampling and detailed measurements of temperatures, flue gas species as well as convective and radioactive heat fluxes. Moreover the DS® burner was modified to DS®T burner for the use of dense phase fuel conveying for indirect firing systems including the oxyfuel process.

Impact of Selected Parameters on the Behaviour of Mercury in Pulverised Coal fired Power Stations

Harald Thorwarth

At coal-fired thermal power stations fuel is fed to the system. With the fuel organic but also inorganic substances and trace elements like mercury are fed to the process, too. Mercury can leave the system with the bottom ash or fly ash, with gypsum or waste-water via the flue gas desulphurisation plant or with the clean gas through the stack. The behaviour of mercury in the system is influenced by a number of different parameters, the meaning and influence of which are being presented and discussed.

The Fate of Mercury in Coal-fired Power Plants in the Netherlands

Henk te Winkel

About 30% of the electricity produced in the Netherlands is generated from coal, all of which is imported. At the same time, the co-combustion of biomass is becoming increasingly important. For the past 25 years, the fate of the (trace) elements in general and of mercury in particular has been studied in great detail. The results indicate that on average the removal of mercury at co-combustion of biomass is similar to the average removal found for full coal-firing.