Abstracts - VGB PowerTech Journal 3/2017
Editorial: The sun rises in the East for power plant chemistry
Mehmet Topeli
In the past decade, fossil fuelled electricity production has been under pressure from highly subsidised renewable energy sources. Moreover, in the aftermath of the Fukushima Daiichi nuclear disaster in 2011, there has been continuous (r)evolution in the electric power sector. [more...]
The value of flexibility for fossil-fired power plants under the conditions of the Strommarkt 2.0
Sascha Lüdge
Sascha Lüdge This article evaluates the current situation of the German energy market by looking back to goals and decisions from the 1990’s. It is set into relation with energy demand, retail prices for electricity and energy prices on the whole sale market. Additionally the grid stability with the indicator redispatch is investigated. Furthermore it describes the economic situation of fossil fuel fired power plants with the current investment environment and gives an opinion if the market develops more in the direction of a liberated free energy market or backwards to a regulated market.
Taken measures and experiences to ensure flexible operation of steam turbogenerators
Marco Redieß, Alette Bläser, Frank Golde, Frank Günther and Hans-Peter Tielsch
Lausitz Energie Kraftwerke AG operates 14 lignite-fired power plant units generating a total gross output of approximately 9.000 MW. These units are specified and designed for base load opera-tion, and they have been operated in this way so far. For the increasingly flexible operation of steam turbine sets, technical measures that promote safe and economic operation are necessary. Among them is ventilation monitoring, including protec-tive functions for high pressure and low pressure turbines. Additionally, this leads to new re-quirements regarding vibration monitoring at low pressure last stage blades and modifications of the exhaust pressure protection curve as well as further optimisation of operation.
Assessment of the condition of reheater 1 at Schwarze Pumpe power station with the use of innovative and efficient measuring equipment
Thomas Porsche, Andreas Mengel, Jens-Uwe Neumann, Patrick Kozlowski and Lars Barkowski
This article discusses the use of a new non-destructive testing technology not previously applied in Europe in conventional lignite-fired power plants. The effects of erosion at a power station led to diminished strength and material fatigue on a large scale and resulted in damage to four boilers. By using far-field technology, it was possible to reduce the time for check significantly. The process validation procedure showed that the method which was applied was more accurate in this specific case than the conventional ultrasonic measurement.
Last stage blade trailing edge erosion feedback in EDF LP turbines with flexible operation
Hamza Heddoun and Jean-Marc Richard
Among EDF’s thermal fleet, some are elder fossil-fired units which were not designed for the increasing flexible operation. These units have been operated for many years with good performance, but new issues have occurred recently. One issue is the erosion on last stage blade trailing edges. A complete analysis including 3D-calculation was carried out, with results readjusted to on-site blade vibration monitoring measurements. An erosion criterion was developed and a practical and cheap methodology to monitor the erosion against this criterion.
On-line chemistry monitoring concept for Kusile and Medupi, Eskom’s new coal-fired stations
Ken Galt
Eskom is currently undertaking a new-build programme that will add two giant new supercritical coal-fired stations, Medupi and Kusile. An extensively revised on-line monitoring concept has been implemented. With the exception of corrosion products analysis, routine laboratory analysis has effectively been eliminated, and switched to on-line monitoring. This has resulted in a significant increase in the number and diversity of instruments deployed, which allows for early identification of developing problems and for on-line verification and validation of excursions, reducing/eliminating the need for grab samples. The signals from the analysers are transmitted via the DCS and/or a dedicated analyser network and presented to the on-site chemists by means of an expert system.
13 years operational experience with a coal fired power plant in the area of chemistry and the challenges ahead
Mehmet Topeli and Ceren Davutluoglu
Technology providers often supply the technology and observe the operations up to two years, only during the warranty period. However, in the mid–long term, power plant operators are facing with different kind of problems and developing their own remedies. In this study the major problems, in the area of chemistry, which have been encountered so far in a coal fired power plant in Turkey and the remedies that were developed will be discussed.
Regeneration of SCR catalysts – Investigations on influencing factors on the wet cleaning process
Anne Wiesel, Anja Schuster uad Herwig Maier
Since the mid-1990s the investigation of deactivation mechanisms of SCR catalysts has been an important issue. One intention is to avoid unscheduled outages of thermal power units due to sudden failure of the SCR catalysts. Another intention is the development of methods and processes to reactivate exhausted catalysts. During the last years, extensive investigations for the further optimisation of the process have been conducted using a pilot plant that was built for this purpose at the power station Altbach. The investigations were mainly related to the wet cleaning step, trying to influence the solubility of the blocking substances on the catalyst surface by addition of chemicals or variation of the temperature.
Deactivation of SCR catalysts by potassium: A study of potential alkali barrier materials
Brian Kjærgaard Olsen, Frauke Kügler, Francesco Castellino, Leonhard Schill, Rasmus Fehrmann and Anker Degn Jensen
The use of coatings in order to protect vanadia based SCR catalysts against potassium poisoning has been studied by lab- and pilot-scale experiments. Three-layer pellets were used to test the ability of the barrier layer to block the diffusion of potassium across the pellet. MgO was the most effective potassium barrier. Despite some observations, the coating did protect the SCR catalyst against potassium poisoning to some degree, leaving promise of further optimisation.
Conventional resin cation exchangers versus EDI for CACE measurement in power plants – Feasibility and practical field results
Manuel Sigrist
The conductivity measurement after a cation exchanger in power plants with steam turbines was introduced soon after 1950 by Larson and Lane. Due to the simple measuring principle, the sensitivity to ionic contaminations and to its high reliability, the conductivity measurement after a cation exchanger (CACE) has become the most commonly used online analytical method in power plants with steam generators. Swan has investigated electro deionisation (EDI) as substitution of the conventional cation exchange resin and has developed a new conductivity instrument using this principle. This paper provides a description of the conventional method for cation conductivity measurements as well as of the new AMI CACE using EDI method.
Expert opinion on BAT-associated emission levels (BAT-AELs) for mercury emissions to air from existing lignite-fired power plants with pulverised combustion (PC) boilers in the LCP BREF review process
Alfons Kather
The BAT-associated emission levels (BAT-AELs) to air for mercury (Hg) from existing lignite- fired power plants with a total rated thermal input (MWth) ≥ 300 are set in the LCP BREF final draft [1] between < 1 and 7 μg/Nm3 on a yearly average basis. Taking into account the results of this study, the range for the new BAT-AEL for Hg emissions of existing lignite-fired power plants with PC boilers should be set between 5 and 9 μg/Nm3 if the Hg content of the lignite is less than 0.22 mg/kg (dry basis). Higher mercury contents in the fuel than 0.22 mg/kg have to be taken into account within the approval process of the affected plant.
Measuring device and system security for IT security proofs
Franka Schuster, Andreas Paul and Hartmut König
With the introduction of a German law for increasing security of information technology systems (IT-Sicherheitsgesetz), new challenges arise for operators of plants and networks. The obligation to regularly enhance and prove IT security forces operators to find means to measure and document their current IT protection state. Although, also in the past several existing industry-specific guidelines called for the application of processes to measure IT security, up to now, the development and implementation of such processes is individual and reserved to big companies capable to handle the necessary effort.
Flameless burners with high capacities in the range of several MW for coal-fired power plants
Joachim G. Wünning
Flameless burners are often installed in natural gas heated industrial furnaces to achieve low NOx-emissions without exhaust gas treatment. The technology of Flameless Oxidation – FLOX largely suppresses thermal NO formation. To apply this technology for coal combustion was considered early. This report should give an overview about research and development in this field.