Abstracts - VGB PowerTech Journal 3/2016
Editorial: Power plant chemistry today
Dr. Anne Wiesel
The tense situation, in which the conventional power plants are at the moment, should be well-known to the reader of the VGB PowerTech journal. However, what are the consequences for power plant chemistry? Which tasks do the chemists fulfil in the operation of the power plants, today and in the future?[more...]
The plant “Obervermuntwerk II” and its flexibility
Peter Matt
Energy storage and flexible generation are key elements to cover the secure electricity supply in the future. Today pumped hydro storage ((PHS) and storage plants are the most efficient and reliable way to meet the challenge of flexibility and large scale storage with a low carbon footprint. PHS Kops II was commissioned in 2008; since this time every unit has been operating for more than 8,000 hours a year. Now PHS Obervermuntwerk II is under construction and will be commissioned in 2018. The technical challenge is the 100 % flexibility from –180 MW to +180 MW by using the hydraulic short circuit. The two units are designed as ternary machine sets with Francis turbine without part load limits, generator and pump.
The RDK 8: Ultra supercritical boiler, a showcase for the next coal-fired plant generation
Georg-Nikolaus Stamatelopoulos and Heinz Lorey
Coal-fired power plants will continue to play an important role for the European energy supply, both in terms of securing this supply, as well as keeping the cost of electricity at an affordable level. The new Karlsruhe RDK 8 power plant, fired with bituminous coal, has an electrical output of 912 MWel. The overall plant efficiency is over 47 %, and the additional combined district heat production (max. 250 MWth) leads to more than 60 % of fuel utilisation. An overview of the RDK 8 boiler design and the project realization is given. The experience and improvements implemented during the construction phase as well as during commissioning are also presented.
Combustion characterisation of fuels for power plants: From laboratory experiments to boiler furnace simulation
Martin Schiemann, Sven Haarmann, Siegmar Wirtz, Viktor Scherer, Martin Ehmann and Christian Kuhr
The investigation of the combustion behaviour of pulverised solid fuels leads to improved understanding of the combustion mechanisms. As the combustion properties of carbonaceous fuels are varying with the fuels origin, experimentally derived reaction rate parameters which describe the individual fuel conversion are mandatorily needed for the final design of pulverized fuel boilers. As the experiments show, the higher reactivity of the torrefied wood sample leads to significant changes in local combustion processes and the integral boiler performance.
Future demand and capacity utilisation of conventional power plants in Germany: A meta-study
Alexander Buttler and Hartmut Spliethoff
Despite of the transition of the German energy system towards a renewable based energy system, conventional power plants will play a key role to guarantee the security of supply. Within a meta-analysis at the Institute for Energy Systems of the TU Munich, the future need of flexible conventional power plants in Germany and the impact on capacity utilisation in the context of the boundary conditions were investigated. After 2020 most of the studies expect a need of additional conventional power plant capacities. Until 2050 the overall need of new capacities in the scenarios under investigation lies in the range of 0 to 53 GW.
A comparative study of gas engines and gas turbines in combined heat and power generation for a typical public heat supply network
Tobias Vogel, Gerd Oeljeklaus, Thomas Polklas, Christian Frekers and Klaus Görner
One central target of the German “Energiewende” is efficiency enhancement using fossil energy. Due to the German climatic conditions, the combined heat and power (CHP) generation is a suitable instrument to achieve this goal. Therefore, it is part of the new energy concept of the German Federal Government. But owing to the changing market associated to the Energiewende, also other technologies move into spotlight, like large, stationary, highefficient gas engines.
Indications of power boiler tube leaks and factors affecting decision making for taking leaking boilers out of operation
Behzad Boroumandi
In spite of remarkable progress in boiler design and manufacturing and also the development of new techniques, such as acoustic leak detection, chemical mass balance, input/loss method and the like for early detection of tube leaks as per NERC tube failure is still one of the main causes of outages or derating of power generating units. Detection of tube leakage is presented at different heating sections of a boiler by observing operating parameters and certain recommendations have been made regarding nature of actions which can be taken.
The application of degassed conductivity in DONG Energy thermal power plants
Monika Nielsen
Measuring of conductivity is the primary measurement for online quality control of the water steam cycle carried out in all of the power plants in DONG Energy Thermal Power. In most plants, only specific and acid conductivity measurement devices are installed as stationary online analysers. At the Asnæs power plant (ASV) in Kalundborg, Denmark, there is a known problem with organic matter in the system. Measurement of the degassed conductivity was introduced for solving the problems. In the process of making our plants more flexible, a new operating mode was introduced at the unit 1 of Herning Power Plant in 2014: partial turbine bypass operation. The new operating mode resulted in quite significant disturbances in the water steam chemistry. Degassed conductivity analyser were implemented for troubleshooting.
Membrane systems and their use in nuclear power plants –Treatment of primary coolant
Pavel Kus, Sarka Batova, Martin Skala, Katerina Vonkova, Vaclav Zach and Roman Kopa
In nuclear power plants, drained primary coolant containing boric acid is currently treated in the system of evaporators and by ion exchangers. Replacement of the system of evaporators by membrane system (MS) will result in lower operating cost mainly due to lower operation temperature. In membrane systems the feed primary coolant is separated into two output streams: retentate and permeate. Retentate stream consists of the concentrated boric acid solution together with other components, while permeate stream consists of purified water. Results are presented achieved by testing a pilotplant unit of reverse osmosis in nuclear power plant (NPP) Temelín.
The hexagon of water-steam cycle conservation parameter
Roger A.M. Ertryckx
ENGIE Lab Laborelec drafted a concise blueprint of chemistry guidelines applicable to boiler conservation. These conservation guidelines frame six parameters, i.e. the hexagon of parameters, similar to the approach of the actual international guideline philosophy with alarm levels (AL) and target levels (TL). Additionally, the main goal of the conservation programme is to minimise corrosion rate, no longer to the lowest possible level but as low as reasonably achievable.
Mercury removal in wet flue gas cleaning systems – the interaction of chemistry and process control
Margot Bittig, Stefan Haep and Dieter Bathen
The removal of mercury is one of the most demanding tasks within flue gas treatment systems. This is partly due to the fact that mercury occurs in different states of oxidation in the flue gas. These different species show different adsorption and absorption properties. An overview of the reaction mechanisms is given affecting mercury removal. Furthermore the influence of operating parameters like temperature, redox potential and pH value is discussed.
Sulphuric acid measurements at ppb levels at a natural gas-fired CCGT
Christine Koczab, Frans van Dijen, Chothani Chetan and Mark Lauwers
The Heat Recovery Steam Generators (HRSGs) operated as part of Combined Cycle Gas Turbine (CCGT) power stations experience Sulphuric Acid corrosion due to the Sulphur in the fuel. This in turn, causes emissions and immissions of acid particles. Under this project, flue gas measurements of SO2, SO3/H2SO4 and Acid Dew Point (ADP) were performed at a HRSG at such a site. This project demonstrated that measurement of SO2 and SO3 at ppb levels in “clean” flue gases seems possible, and further it seems also possible to measure the ADP of “clean” flue gases to levels below 80°C.
Alternative method for the measurement of the CO2-degassed acid conductivity
Heiko Woizick
The measurement of the CO2-degassed acid conductivity was established for water and steam quality assessment in power plants within the last years. Considering the CO2-degassed acid conductivity in most cases allows steam to be fed on the steam turbine much earlier. Therefore, the efficiency of the power plant can be improved significantly. The performance of the method has been proven within tests in the power plant Köln-Merkenich. In comparison with conventional methods lower conductivity values and significantly shorter reaction times were observed.
Beyond standards and regulatory acts – Qualified special tests with the help of ultrasonic tomography
Jörg Schenkel, Claas Lehmkuhl and Hans Christian Schröder
Large-scale power plants repeatedly present new challenges for the non-destructive testing (NDT) of materials. Test standards and methods that have been used so far sometimes prove unreliable or inefficient. A VGB “Boiler Recirculation Systems” Working Group was established to clarify open issues. An approach drawn from the field of nuclear engineering presents itself for cases involving special test tasks that cannot be solved by the application of regulatory acts or standards. One example is the qualification of a new ultrasonic tomography test method.