Abstracts - VGB PowerTech Journal 11/2014

Influence of renewable energy on the current and future generation system

Uwe Schulz and Manfred Kins

With the approval of the energy concept of the German Government in 2010 and the revision in 2011, the turnaround in energy policy (Energiewende) was initiated in Germany. In the last 10 years the installed power of wind and solar generation tripled and the electricity generation based on these sources was even quadrupled. A further growth in renewable development will be expected so that with an increased share of renewables in electricity generation a serious modification in design and dimensioning of new conventional power plants has to be expected. In addition to changes in the electricity market and these will be probably be the most important challenge in the future.

The Erding geothermal project

Andreas Böffel

In 1983, during exploratory drilling for oil, thermal water was found at a depth of around 2,350 m in the outskirts of the town of Erding/ Germany. Starting with that drill hole, a new district heating network was established in several stages over the course of almost 20 years. Now, the district heating system in the county town of Erding in Upper Bavaria, which has a population of around 34,000, has reached a thermal connected load of nearly 60 MW. The impetus for implementing the project was initially provided by the county and the town council of Erding. A local authority working group was formed to explore ideas for use of the thermal water and to pursue its practical implementation.

Research into co-combustion on European level – RECOMBIO, FP7 Project

Eva Miller, Aaron Fuller, Jörg Maier, Günter Scheffknecht, Thomas Glorius, Hans-Joachim Gehrmann and Helmut Seifert

Under the EU Seventh Framework Program, the RECOMBIO (REcovered fuels COMbined with BIOmass) project aimed at developing innovative approaches towards the high efficient co-utilisation of low quality biomass and Solid Recovered Fuel in CHP plants. The overarching goal of the RECOMBIO project was to enhance the use of biomass and SRFs in order to promote the creation of a sustainable energy market across Europe, especially in terms of cost-efficient reduction of CO2 emissions to the atmosphere. The application of biomass/SRF in demonstration plants was investigated within the scope of the project. Among others, the fuels were co-combusted in a circulating fluidised bed (CFB).

Modifications of hard coal-fired power plants in view of extended coal range

Andreas Schmidt

Steag operates a number of hard coal-fired power stations at different sites in Germany which were erected in the neighbourhood of coal mines and are designed for the use of local coal. Caused by the political decision to abandon hard coal mining in Germany by 2018, the increased utilisation of imported coal is unavoidable over the years. As hard coal is a natural product it varies from mine to mine which is a new challenge for existing power plants. Therefore the use of an enhanced coal range needs more or less minor or comprehensive modifications in these plants.

Ignition behaviour of pulverised solid fuel particles at hot surfaces

Alfons Leisse, Sebastian Rehfeldt and Dirk Mayer

Due to increasing power generation from renewables the need for flexibility of fossil power plant results in daily shutdown and start-up procedures of mills and burner groups followed by serious increase of expenses. On this account, ignition of pulverised solid fuel particles without use of liquid or gaseous fuels is of vital importance. Due to their well-known stability characteristics, burners of the DS type provide best requirements for alternative ignition processes. The vital importance of the fuel nozzle temperature was demonstrated in lots of measurements with DS® Burners. With the focus on that component in mind and a suitable start-up system for coal burners as target for further development, Mitsubishi Hitachi Power started investigations on the potential a DS® Burner in a test rig, supported by E.ON.

Ceramic tile systems in circulated fluidised bed power stations – An alternative refractory lining concept for highly stressed combustion chambers and cyclones

Markus Horn, Ulrich Ehrentraut and Frieder Schell

The use of alternative fuels, such as biomass, refuse-derived fuels (RDF) and others for thermal combustion is state of the art in many power plants. All these fuels have a different calorific value and are preferably used by fluidised bed power plants. New requirements to be met by power plants like frequent start-up and shutdown lead to new problems which result in increased wear and stress on the refractory lining in almost all power plants subjected to these conditions. Jünger+Gräter carefully observed this trend in the past and have already started to work on the intensive development of suited refractory systems for this foreseeable problem in the future.

Advanced AQSC technology for further emission control

Takanori Nakamoto, Hiroyuki Nosaka, Noriaki Taniguchi and Shogo Mori

Mitsubishi-Hitachi Power Systems Ltd. (MHPS) developed the Advanced AQCS (Air Quality Control System) which contributes to achieve ultra-low dust and SO3 emissions since the 1990s, and the first Advanced AQCS started its operation in 1997. Since then, this Advanced AQCS technology has already been applied to twenty power plants commercially as “Best Available Technology” (BAT) for the new coalfired unit and all the plants have been operated successfully. It is among the biggest advantages of the Advanced AQCS that no use of special equipment, made of costly materials, has to be made. Its superior emission control performance can be obtained just by means of the system configuration change.

Operational monitoring and maintenance and modernisation of the condenser

Tobias Ellsel, Frank Udo Leidich and Wienfrid Schulz

The condenser is one of the key components of steam power plants. By improvement of the heat transfer rate, the reduction of the steam side pressure loss and avoidance of sub-cooling, an almost similar gain in performance can be achieved as it would be possible by increasing the super-heating and reheating temperature. Therefore the operational monitoring and maintenance as well as modernisation of the condenser are of major importance for the profitability of the power plant.

Mechanised UT – Inspection of turbine shafts during outages according to the latest state of the art

Klaus Leupoldt

The UT inspection of turbine rotors is one of the standard tasks performed during outages/ inspections in power plants. Actemium NDS Nürnberg is among the leading suppliers of UT inspection devices for turbine rotors and discs and since recently also for plants testing discs of wind power plants. The combination of own experience upon testing during manufacturing and upon inspections as well as plant know-how enable the provision of mechanised testing routines with mobile test rigs. The paper presents among others the testing technique and its application together with the TURO-MAN test plants in a conventional power plant.

Implementation of multiple measures to improve reactor recirculation pump sealing performance in nuclear boiling water reactor service

Gerard van Loenhout and Jürg Hurni

A modern reactor recirculation pump circulates a large volume of high temperature, very pure water from the reactor pressure vessel back to the core. A crucial technical problem with a recirculation pump, such as a mechanical seal indicating loss of sealing pressure, may result in a power station having to shut down for repair. The paper describes the sudden increase in stray current phenomenon leading to rapid and severe deterioration of the mechanical end face shaft seal in a reactor recirculation pump. This occurred after the installation of a variable frequency converter replacing the original motorgenerator set.

The wet limestone-gypsum FGD and the value of the ORP

Frans van Dijen

For obtaining excellent results with the wet limestone gypsum FGD, measurement and control of the ORP of the FGD is required. This can also allow for operating the FGD at reduced costs by limiting the consumption of compressed air. The value of the ORP is also of importance regarding the purification of FGD effluent. The paper explains the influence of the value of the ORP on some trace elements and trace compounds, like I, Br, Cr, Hg, Mn, Se, sulphide, S-N compounds and AOX. Laborelec recommends operating the FGD at certain values of the ORP.

Effective use of pre-job briefing as tool for the prevention of human error

Ansgar Schlump

There is a fundamental demand to minimise the risks for workers and facilities while executing maintenance work. To ensure that facilities are secure and reliable, any deviation from normal operation behaviour has to be avoided. Accurate planning is the basis for minimising mistakes and making work more secure. All workers involved should understand how the work should be done and what is expected to avoid human errors. Especially in nuclear power plants, the human performance tools (HPT) have proved to be an effective instrument to minimise human errors.