Abstracts - VGB PowerTech Journal 4/2009

USC 700 °C Power Technology - A European Success Story

Rudolph Blum, Jorgen Bugge and Sven Kjaer

For more than ten years, the European power industry has worked successfully on the development of AD700. Most of the targets have been achieved according to schedule and the developments can now be employed in a concept for the first 700 °C power plant with efficiencies > 50 %. A major part of this development is not only applicable to 700 °C power plants but can also improve the efficiency and construction costs of current USC standard plants.

Operational Experience with the Combustion Load Control System of a Boiler Plant with a Moving Grate Stoker

Werner Auel, Werner Bruns und Fank Oellers

The key component of a firing system in thermal waste treatment is the moving grate. The control concept defines the different phases of the control disturbances. The operating results based on this basic concept indicate a well-balanced controlled quality before and after load changes. Other means to improve control quality using additional measurement systems are also discussed.

Ultra-low NOx Combustion in Industrial Water-steam Systems

Marco Derksen

The application of premixed combustion for use in industrial boilers is introduced. First, the article deals with the prevalent NOx formation routes in industrial boilers. Then some conventional NOx reducing measures will be discussed, including staging of fuel or air and the application of flue gas recirculation. The realisation is introduced for a new gas burner. Experiments with the burner have resulted in NOx emissions < 9 mg at 3 % O2, with negligible CO emissions.

Probabilistic Approach to Determining the Optimum Replacement of a Superheater Stage in 680 MW Coal-fired Boiler

Jan Robert Bos and Ruud van der Star

The boiler of the NUON power plant HW08 that went into operation in 1993 is designed as Benson boiler and mainly fired with hard coal. A creep-related tube failure occurred in the tertiary superheater that had been due to increased wall temperature caused by steam side formation of oxide layers. The theoretical lifetime of the components was calculated with the aid of the results of steam side oxide measurements and condition evaluation of the tertiary superheater with the aid of tube samples. The objective is to establish an operation and maintenance schedule for the desired operating lifetime of 300,000 hours.

Innovative Connections for Steam Generators - Elimination of Leakages and Minimisation of Assembly and Idle Times -

Alfred Schlemenat and Karl Burmann

In the non-positive and positive locking technology described for detachable connections of rotation symmetrical components, screws and bolts do not transfer any loads and stresses. Use in all kinds of industrial applications shows the revolutionary advantages in comparison to common connections. The steam cooling in the Hanover power plant is being equipped with this technology in order to eliminate leakages.

Thermo-chemical Calculations to Predict the Deposit Formation Behaviour of Rhenish Lignite

Muhammad Muhammadieh, Bernd Meyer and Markus Neuroth

Based on the computing programme SimuSage, key figure functions were developed that permit both the aluminosilicate slagging potential and the sulphatic caking potential of lignites with different compositions to be represented depending on temperature. The calculations confirm the approach that has successfully been adopted by RWE Power to use coal with a tendency to form deposits either in boilers with low furnace heat release or combust them after blending with other appropriate lignites.

Extended Laboratory Testing Methods and Their Application in Connection with the Grinding and Ignition Behaviour of Fuels

Herbert Prenzel, Daniel Haxter, Anna Dux and Jacek Zelkowski

The results of an immediate analysis and the determination of the calorific characteristics (net calorific value and gross calorific value) provide an overview about the quality of a coal or a coal shipment. However, the unambiguous interpretation of the analytical results is, in many cases, not easy in view of the operating behaviour of combustion systems which are permanently exposed to extreme loads. This particularly applies to blends of relatively different coals. The E.ON Engineering central laboratory has introduced and successfully implemented two of these methods including the so-called Clausthal grindability test and a measuring method for determining the ignitibility of coals in pulverised coal combustion systems.

Experimental Method for Investigating Radiative and Conductive Properties of Ash Deposits from Coal-fired Power Plants

Sebastian Bohnes, Viktor Scherer and Siegmar Wirtz

During solid fuel combustion ash residues arise and form deposits on the heating surfaces. Because of their thermal properties the deposits act as thermal barrier which influence the heat transfer significantly and lead to a degradation of conversion efficiency. Within the scope of an AiF Project the radiative properties, spectral emittance, as well the conductive properties, thermal diffusivity, of deposits from lignite and hard coal-fired boilers were investigated in order to derive findings for the influence in large-scale plants.

Stationary Design Calculation and Part Load and Dynamic Simulation as well as Validation of Energy Conversion and Power Plant Cycles

Bogdan Apascaritei, Andreas Hauschke, Reinhard Leithner, Christian Schlitzberger and Henning Zindler

In this article the program ENBIPRO will be presented, with which stationary design calculations and part and full load simulations, as well as dynamical simulations and data validation can be accomplished according to the VDI guidelines 2048 of energy systems in an implicit, non-linear, differential-algebraic system of equations. The system of equations is solved using the predictor-corrector-method (PECE). To demonstrate the capability and efficiency of the program, results of cycle calculations with ENBIPRO will be presented. These cycle calculations include calciumoxide-calciumcarbonate cycles (CaO-CaCO3) for CO2 separation from flue gas, optimisation of solar-energy plants, solid oxide fuel cell-(SOFC) systems, an Alstom gas turbine (GT-26) and combined cycle, ORC cycles for geothermal power plants, refuse derived fuel (RDF) plants and compressed air energy storage (CAES) combined cycles power plants.

Development of an Economic Post-combustion Carbon Capture Process

Tobias Jockenhövel, Rüdiger Schneider and Helmut Rode

E.ON and Siemens are committed to combat against climate change and are preparing the next step towards large-scale demonstration with their co-operation in the POSTCAP project. Siemens is developing an improved post-combustion CO2 capture process with minimised energy demand, optimised for integration in conventional coal-fired power plants. The pilot plant - based on amino-acid salts for CO2 capture - will start operation in August 2009 for further process validation and solvent optimisation.

Future Coal-based Power Generation Using Amines for Carbon Capture a Comparison of Environmental Impacts from a Life Cycle Perspective

Petra Zapp, Andrea Schreiber and Wilhelm Kuckshinrichs

A Life Cycle Assessment (LCA) is used as basis to compare hard coal-based electricity generation with and without CO2 capture for five power plants that have been installed at different points in time. Retrofit as well as an integrated carbon capture process with monoethanolamine scrubbing (MEA) will be analysed. Specific CO2 emissions can be drastically decreased, however, other specific emissions and their related environmental impacts can increase.