Abstracts - VGB PowerTech Journal 11/2008

Analysis and Optimisation of Operation of Modern Hard Coal-fired Power Plants through Simulation

Wolfgang Zehtner, Hartmut Spliethoff and Wolfgang Woyke

The quality of control and process engineering concepts can already be optimised project-specifically in basic engineering with the support of simulation: automation level, plant safety, availability and efficiency are – similar to plant dynamics – important aims of optimisation which have to be considered carefully.

Modification of the Power Plant L57 in Krefeld-Uerdingen Based on CFD

Thomas Klasen and Roland Klein

The pipes of the heat exchangers of the fluidised bed boiler in Krefeld-Uerdingen were to be modified because of erosion. Thus, it was necessary to analyse the current case and an optimised case by CFD simulations. After the first operating phase, no wear at the heating tubes could be detected. The CO and dust values also decreased.

Experience with Modern Hard Coal Firing Systems

Hellmuth Brüggemann

Increased combustion efficiency and reduced combustion air need to be well harmonised and controlled to fulfil all relevant requirements as low primary emissions, efficient combustion while maintaining a protective atmosphere at the furnace walls. The paper describes the consequent further development of jet burners. The proven jet burner technology could be further developed thanks to feedback of experience made with new power projects and retrofit jobs.

New Experience Gained from Operating DS (Swirl Stage) Burners

Alfons Leisse and Dieter Lasthaus

The requirement of environmentally-friendly power generation has led to a widespread introduction of air quality control systems in fossil-fired power stations in the past two decades. Almost simultaneously the development of a combustion technology started that enabled steam generators to comply more favourable with the prerequisites for adapting the legal and statutory licence requirements by means of reducing the nitrogen oxide emissions on the primary side. DS burners are currently showing their great performance potential in many new designed and converted steam generators.

Co-combustion of Solid Recovered Fuels with Rhenish Lignite

Alexander Gerhardt, Bernhard Röper, Jörg Maier, Günter Scheffknecht, Thomas Glorius and Martin de Jong

The RECOFUEL project, which was funded by the European Commission, focused on the production of high-calorific solid recovered fuels (SRF) as well as on the co-combustion of these fuels in coal-fired power plants. For the test campaigns in two lignite-fired power plants of RWE Power AG, a RAL-approved SRF was used. This fuel was also analysed thoroughly during the campaigns. The results emphasize that continuous co-combustion of quality-assured SRFs in lignite-fired power plants is feasible under appropriate boundary conditions.

Import Coal as a Challenge for Dust Separation in Electrostatic Precipitators

Hermann Brüggendick, Horst Rhein and Thomas Riethmann

Dust separation by using an electrostatic precipitator (ESP) is an important challenge for air pollution control. Within these investigations, hard coal from Germany, Russia, Columbia, Poland, South Africa and Australia were rated, and the individual components and their influence on the precipitation is analysed and presented.

KEMBUS: Non-intrusive Testing and Degradation Trending of Boiler Tubes

Coen Boxma and Jan W. Noteboom

Boiler tubes might suffer from LowNOx corrosion, corrosion caused by co-firing and for other corrosive and erosive reasons. KEMBUS provides the possibility to test tubes from the boiler outside. As a tool for pre-inspection to assess required maintenance measures (such as repair welding or tube replacement) KEMBUS has already shown to be invaluable.

Future Fly Ash Marketing

Rudolf Mauder and Andreas Hugot

It can be assumed that the fly ash production volumes will undergo a marked increase over the next few years. The conditions of fly ash production will improve as a result of modern and refurbished power plants, yielding a positive effect on the quality of fly ashes. Other vital parameters of future fly ash marketing are fly ash logistics and the infrastructure of power plants. Basically, economic utilisation of the increased production volumes is possible; however, new and long-term strategies are necessary.

Mass Concrete with Fly Ash in Power Plant- and Industrial Construction

Peter Giesbrecht

For more than 50 years coal fly ash has been successfully used in concrete as a mineral admixture to improve workability of fresh concrete, reducing temperature rise during initial hydration, resistance to sulphates and contribution of durability and strength of hardened concrete. Systematic studies of recent years have confirmed practical experiences, i.e. the application of coal fly ash significantly increases sulphate resistance of concrete.

Frost Resistant Air-entrained Concrete (XF3) with Fly Ash in Hydraulic Engineering

Johannes Brandl

The Isar canal was refurbished in order to fulfil the requirements regarding frost resistance in the area of the changing water levels. Fly ash concretes from 80 to 120 kg fly ash per m3 concrete had been produced with which the air content was generated by addition of an air entraining agent. The fly ash concrete with air voids produced by using air entraining agents is resistant to freeze thaw changes and fulfils the requirements for a concrete of the exposure class XF3.

Regulations for the Utilisation of Fly Ash in Concrete – Today, Tomorrow and the Day after Tomorrow

Udo Wiens

Several changes in the product standards for fly ash as well as the national regulations for its utilisation had been published in the last years. Now, fly ash may be taken into account for the calculation of the water cement ratio (w/ceq) as well as for the minimum cement content. Within ongoing research projects the effectiveness of fly ash to avoid concrete damaging structures by alkali-silica reaction is going to be investigated. The results may be implemented in prospective normative regulations.

CO₂ Capture Based on Chemical and Carbonate Looping

Bernd Epple and Jochen Ströhle

Chemical and carbonate looping are two efficient and environmentally sound processes for CO₂ capture from fossil-fired power plants. Both processes promise high plant efficiencies and low CO₂ avoidance costs compared to other CO₂ capture technologies but are still at an early state of development. The paper provides a brief overview of the state of the art.

Firing Issues Related to the Oxyfuel Process

Günter Scheffknecht and Jörg Maier

In the oxyfuel process combustion takes place in an atmosphere consisting of carbon dioxide, moisture and oxygen. This gives rise to various questions related to firing, in particular with regard to the sequence of combustion, pollutant reduction, the risk of corrosion and the properties of the fly ash or the deposits that develop. 

Alarming Alarms!

Jos W. Menting and Riaz Tejani

Modern power plant control systems can pass on a lot of alarm signals. For reasons of optimisation and to avoid a possibly confusing number of messages, process automation systems are to be based on a sound alarm philosophy that is being maintained correspondingly. The paper describes a target-oriented methodology for optimised alarm systems.

Aspects of Emission Control for Thermal Waste Treatment

Nicole Denise Rademacher

The new provisions according to the draft of the 37th Ordinance for Emission Control will have a severe impact on the operation and construction plans for power stations. It is very important for power plant operators to pay attention to international conventions or the legal framework of the EU that is legally binding for Germany.